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UCL dissertation focusing on the environmental impacts of rare earth oxide production in two Chinese mines.

UCL dissertation focusing on the environmental impacts of rare earth oxide production in two Chinese mines.

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    Production of rare earth oxides Production of rare earth oxides Document Transcript

    • Production of rare earth oxidesAssessment of the environmental impacts in two Chinese minesDissertation for the Master of Science inEnvironmental Systems EngineeringAländji BOUORAKIMASupervisor: Julia STEGEMANNUniversity College LondonDepartment of Civil, Environmental & Geomatic EngineeringLondon, United Kingdom, September 2011
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    • Abstract The recent interest in environmental friendly technologies has created a significantincrease in the demand of rare earths. Rare earths are indeed used in many applications(e.g. car electric batteries, rechargeable batteries, energy saving light bulbs) because oftheir specific properties. As such, it was interesting to shed a light on the environmentalcost of producing these rare earths. Thus, this study aims at determining the different environmental impacts fromproducing rare earth. It appraises the impacts from the mining of virgin ore until theproduction of rare earth oxides (which is the most commonly used and produced form ofrare earth). This study focuses on two Chinese deposits (Bayan Obo and Maoniuping) thataccount for 70% of the world production of rare earths. After two literature reviews describing firstly the rare earth market and then theprocesses used in the two deposits, the emphasis is laid on the life cycle assessmentmethodology. Based on both data collected in the literature reviews and personalestimations, the life cycle assessment is carried out using a standardised methodology. As a result, the environmental impacts of producing rare earth oxide are assessedregarding the following categories: global warming, acidification, eutrophication,radioactive waste generation, land use and toxicity in wastewaters. To conclude, on the one hand this study provides an extensive analysis of rareearths in general, then it describes in detail the two biggest mines presently in operations.On the other hand, the life cycle assessment methodology provides results concerning sixdifferent impact categories. These results are potentially generalizable since it appraisesgeneric processes to this industry. This study can be useful to whoever is trying tomeasure the environmental impacts of a product that contains rare earth oxides. Keywords: rare earths, rare earth oxide, life cycle assessment, Chinese rare earths,Bayan Obo, Baotou, Maoniuping, environmental impacts. 3
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    • Acknowledgement I would like to thank Julia Stegemann whose help was invaluable to me. She gaveme the proper advices at the proper times and helped me to design this study from thebeginning to the end. Thanks to her, I have enjoyed carrying out this study. I also would like to express my thanks to Marie for her support. 5
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    • Table of contents 1.   Introduction ....................................................................................................... 15   1.1.   Background information............................................................................. 15   1.2.   Aim of the study ......................................................................................... 16   1.3.   Objectives ................................................................................................... 16   1.4.   Approach .................................................................................................... 16   2.   Information on rare earth elements.................................................................... 17   2.1.   How rare are rare earths? ............................................................................ 17   2.2.   Description of the main rare earth minerals ............................................... 18   2.3.   Description of the rare earth reserves ......................................................... 22   2.4.   Historical production of rare earth oxide.................................................... 22   2.5.   Description of the main applications of the rare earth elements ................ 24   3.   Production of rare earth elements ...................................................................... 27   3.1.   World production of rare earth elements .................................................... 27   3.2.   Chinese production of rare earths ............................................................... 27   3.3.   Prospective other productions .................................................................... 30   4.   Scope refining.................................................................................................... 32   5.   Bayan Obo deposit ............................................................................................ 32   5.1.   Description of the deposit........................................................................... 32   5.2.   Composition of the original ore.................................................................. 32   5.3.   Description of the beneficiation process .................................................... 32   5.4.   Composition of the mixed rare earth concentrate....................................... 34   5.5.   Processing of the mixed rare earth concentrate .......................................... 34   5.6.   Obtaining of rare earth oxides .................................................................... 34   6.   Maoniuping deposit ........................................................................................... 37   6.1.   Description of the deposit........................................................................... 37   6.2.   Composition of the original ore.................................................................. 38   6.3.   Description of the beneficiation process .................................................... 38   6.4.   Processing of the mixed rare earth concentrate .......................................... 40   6.5.   Obtaining of rare earth oxides .................................................................... 40   7.   Life cycle assessment methodology .................................................................. 42   8.   Goal definition and scope .................................................................................. 42   8.1.   Goal of the life cycle assessment................................................................ 42   8.2.   Level of specificity ..................................................................................... 43   7
    • 8.3.   Display of results ........................................................................................ 43   8.4.   Scope of the life cycle assessment.............................................................. 43   8.5.   Guideline to life cycle assessment methodology........................................ 43   9.   Process Modelling: ............................................................................................ 43   9.1.   Bayan Obo deposit ..................................................................................... 43   9.2.   Maoniuping deposit .................................................................................... 51   10.   Life Cycle inventory ........................................................................................ 57   10.1.   Input of chemicals, energy and explosives ............................................... 57   10.2.   Air emissions ............................................................................................ 57   10.3.   Output of wastes and chemicals ............................................................... 57   11.   Life Cycle Impact Assessment ........................................................................ 62   11.1.   Global Warming ....................................................................................... 62   11.2.   Acidification ............................................................................................. 63   11.3.   Eutrophication .......................................................................................... 64   11.4.   Radioactive waste generation ................................................................... 64   11.5.   Land use ................................................................................................... 65   11.6.   Toxic chemical discharge in wastewater .................................................. 65   12.   Life Cycle Interpretation ................................................................................. 67   12.1.   Identification of the significant issues ...................................................... 67   12.2.   Completeness, sensitivity and consistency of data ................................... 68   12.3.   Conclusions of the life cycle assessment.................................................. 70   13.   Conclusion ....................................................................................................... 74  8
    • List of figuresFigure 1: Relative abundance of chemical elements in the Earths crust (Haxel 2002).....17  Figure 2: Concentrations of rare earth elements in the Earth’s crust (Tyler 2004) ...........18  Figure 3: Contents of the main rare earth elements in bastnaesite for two mines (Kingsnorth 2010) .............................................................................................19  Figure 4: Contents of the main rare earth elements in monazite for three deposits (Kingsnorth 2010) .............................................................................................20  Figure 5: Contents of the main rare earth elements in xenotime (Kingsnorth 2010) ........20  Figure 6: Contents of the main rare earth elements in Chinese ionic clays (Kingsnorth 2010) ..................................................................................................................21  Figure 7: Breakdown of the economically viable rare earth resource (USGS 2011) ........22  Figure 8: Global production of rare earth oxide (USGS 2010) .........................................23  Figure 9: World production of rare earth oxides from 1950 to 2000 (Haxel 2002) ..........23  Figure 10: Global rare earth consumption in 2006 (Roskill 2007) ....................................24  Figure 11: Global production of rare earth oxides in 2010 (USGS 2011) .........................27  Figure 12: Breakdown of rare earth oxide-content at Bayan Obo (Crédit Suisse 2011) ...28  Figure 13: Bastnaesite content of rare earth elements at Maoniuping (Spooner 2005) .....29  Figure 14: Ionic clay content of rare earth elements at Longnan (Crédit Suisse 2011).....29  Figure 15: Distribution of the Chinese production of rare earths in 2010 .........................30  Figure 16: Composition by weight of the mixed bastnaesite-monazite concentrate (Wang et al. 2002) .............................................................................................34  Figure 17: Composition of a tonne of rare earth oxides produced from Bayan Obo ore (Spooner 2005) ..................................................................................................37  Figure 18: Composition of the ore in Maoniuping’s mineral (Zhu et al. 2000) ................38  Figure 19: Composition of a tonne of rare earth oxides produced from Maoniuping ore (Spooner 2005) ..................................................................................................40  Figure 20: Beneficiation process in Bayan Obo for one tonne of original rock ................47  Figure 21: Beneficiation process in Maoniuping for one tonne of original rock...............51  Figure 22: Separation factor of rare earths in the Ln(III)-HCl-EHEHPA system (Sato 1989) ..................................................................................................................83  Figure 23: Separation flowsheet for bastnasite (Yan et al. 2006) ......................................83  Figure 24: Relative proportion of light rare earth elements in Bayan Obo concentrate (Spooner 2005) ..................................................................................................85  Figure 25: Relative proportion of light rare earth elements in Maoniuping concentrate...87   9
    • List of tables Table 1: Categorisation of rare earth elements (Hedrick 2010) ........................................... 15   Table 2: Beneficiation process in Bayan Obo...................................................................... 33   Table 3: Processing of mixed rare earth concentrate in Bayan Obo .................................... 35   Table 4: Separation and refining processes in Bayan Obo .................................................. 36   Table 5: Beneficiation process in Maoniuping .................................................................... 39   Table 6: Processing of rare earth concentrate in Maoniuping ............................................. 41   Table 7: Summary of the mining and comminution processes modelling........................... 46   Table 8: Summary of the beneficiation modelling .............................................................. 46   Table 9: Summary of the stoichiometric coefficients in Bayan Obo ................................... 50   Table 10: Summary of the beneficiation modelling in Maoniuping .................................... 53   Table 11: Summary of the mining and comminution processes modelling in Maoniuping 53   Table 12: Summary of the stoichiometric coefficients in Maoniuping ............................... 56   Table 13: Required inputs for the different stages ............................................................... 58   Table 14: Emission to the air during processes in Bayan Obo ............................................ 59   Table 15: Outputs discharged .............................................................................................. 59   Table 16: Impact indicator for global warming ................................................................... 62   Table 17: Impact indicator for acidification ........................................................................ 63   Table 18: Impact indicator for eutrophication ..................................................................... 64   Table 19: Impact indicator for radioactive waste generation............................................... 64   Table 20: Impact indicator for land use ............................................................................... 65   Table 21: Impact indicator for toxicity in wastewater ......................................................... 66   Table 22: Assumptions analysis........................................................................................... 69   Table 23: Calculation of the chemical inputs for Bayan Obo .............................................. 88   Table 24: Calculation of the chemical outputs for Bayan Obo ............................................ 89   Table 25: Calculation of the chemical inputs for Maoniuping ............................................ 91   Table 26: Calculation of the chemical outputs for Maoniuping .......................................... 92   Table 27: CO2 emissions for mining operations ................................................................. 94   Table 28: CO2 emissions from electricity use ..................................................................... 94   Table 29: Calculation of the SO2 emissions ........................................................................ 95   Table 30: Acidification potential characterisation factors (Azapagic 2011) ....................... 95   Table 31: Acidification potential of different chemicals ..................................................... 95   Table 32: Eutrophication potential characterisation factors (Azapagic 2011)..................... 96   Table 33: Eutrophication potential of different chemicals .................................................. 96  10
    • Table 34: Activity in waste slag........................................................................................... 97  Table 35: Activity in wastewater ......................................................................................... 97   11
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    • List of abbreviations GWh gigawatt-hour (109 Wh) kWh kilowatt-hour (103 Wh) MWh megawatt-hour (106 Wh) Mt megatonne (106 t) LCA life cycle assessment LCI life cycle inventory LCIA life cycle impact assessment REE(s) rare earth element(s) REO(s) rare earth oxide(s) t tonne tpd tonne per day 13
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    • 1. Introduction 1.1. Background information Rare earth elements (abbreviated as REE, also called rare earth metals) are a groupof 17 chemical elements. They are all part of the third column of the periodic table andpossess therefore similar chemical and physical features (Hedrick 2000). They are divided into two groups: light REEs and heavy REEs. Table 1 gives information on REEs and the group to which they belong. Table 1: Categorisation of rare earth elements (Hedrick 2010)Chemical  element   Abbreviation   Atomic  Number   Category   Scandium   Sc 21 None 1 Lanthanum   La 57 Cerium   Ce 58 Praseodymium   Pr 59 Neodymium   Nd 60 Light REEs Promethium   Pm 61 Samarium   Sm 62 Europium   Eu 63 Gadolinium   Gd 64 Yttrium   Y 39 Terbium   Tb 65 Dysprosium   Dy 66 Holmium   Ho 67 Heavy REEs Erbium   Er 68 Thulium   Tm 69 Ytterbium   Yb 70 Lutetium   Lu 71 1 Scandium has physical properties that make it impossible to classify as either light 15
    • REEs have become topical because they are found in many technological applications of daily life and notably many green technologies such as wind turbines, recyclable batteries, electric vehicles or compact fluorescent lamps (see 2.5). Since these elements are common in modern life, this report considers the impacts of extracting and producing REEs. REEs exist in several forms (rare earth chlorides, metals, carbonates, oxides, etc.). However, only rare earth oxides (and rare earth metal to a lesser extent) are of interest for industrial applications (Kingsnorth 2010). 1.2. Aim of the study The aim of this study is to assess some of the environmental impacts related to the production of rare earth oxides (REOs). 1.3. Objectives The objectives of this study are as follows: - describe precisely the rare earth market (e.g. production, applications) - select the most representative mines - refine the scope of the study - develop a model representing the processes taking place in these mines - determine a suitable method for measuring the impacts - assess both quantitatively and qualitatively the environmental impacts 1.4. Approach In order to complete the objectives, the study was decomposed into several parts. Firstly, an extensive literature review was carried out with the aim of collecting information on REEs, their minerals, the REE market and their applications. Based on this literature review, it was possible to define the scope of the study and single out two mines for the next step. Secondly a further literature review was conducted to describe and understand the processes to produce REO. This second literature review was used to help build models representing these processes. Thirdly, life cycle assessment was applied to the models developed in the previous section using data extracted from the literature. Finally, the results were discussed.16
    • 2. Information on rare earth elements 2.1. How rare are rare earths? Although they are called rare earths, some of these elements are quite abundant inthe Earth’s crust (Ce is the 25th most abundant elements in the Earth’s crust) and thescarcest of them (Tm and Lu) are even 200 times more abundant than gold (Hedrick 2000;Haxel 2002). One REE, promethium, is a radioactive element with a half-life of 17.7 years for itsmain isotope. As a result, it does not exist naturally. Figure 1 and Figure 2 illustrate the abundance of REEs both relatively to otherelements and quantitatively. Figure 1: Relative abundance of chemical elements in the Earths crust (Haxel 2002) 17
    • 70   Concentration  in  the  Earths  crust    (ppm)   60   50   40   30   20   10   0   Figure 2: Concentrations of rare earth elements in the Earth’s crust (Tyler 2004) 2.2. Description of the main rare earth minerals According to Kanazawa and Kamitani, around 200 different types of rare earth minerals have been reported (Kanazawa and Kamitani 2006). However, in practice, the extraction of REEs relies primarily on four different minerals: • Bastnaesite • Monazite • Xenotime • Ion adsorption clays This is notably due to their high contents of REO. These four minerals account for 90% of economic production of REEs (Roskill 2007). 2.2.1. Bastnaesite Bastnaesite is a fluorocarbonate with the following formula: ReFCO32. The grade of REES in bastnaesite is up to 75%3. Bastnaesite is the primary source of light REO (primarily lanthanum, cerium, praseodymium and neodymium oxides) and accounts for more than 80% of the overall amount of REO in the world (Kanazawa and Kamitani 2006; Roskill 2007; Naumov 2008). Figure 3 illustrates the abundance of the main REEs in bastnaesite. 2 From this point on, the symbol Re represents a rare earth atom. 3 The grade of a mineral is defined as the mass fraction of the REEs in the ore.18
    • %  among  rare  earth  elementss  in   60   USA,  Moutain  Pass   China,  Baiyun  Obo   50   40   bastnaesite     30   20   10   0   Lanthanum   Cerium   Praseodymium   Neodymium   Figure 3: Contents of the main rare earth elements in bastnaesite for two mines (Kingsnorth 2010) 2.2.2. Monazite Monazite is a rare earth phosphate that contains up to 70% REEs (formula: RePO4).With bastnaesite, it represents the most important source of light REEs. Until 1965,monazite was the main source of REEs. It was historically produced as a by-product of sand exploitation. However,nowadays, the production of REEs from monazite has been considerably reduced becauseof radioactivity caused by thorium and radium impurities (ThO2 has a concentration of6-7% in monazite produced from mineral sand operations) (Roskill 2007; Naumov 2008;Kingsnorth 2010). Figure 4 illustrates the abundance of the main REEs in monazite. 19
    • 50   %  among  rare  earth  elements  in  monazite     45   Mt  Weld,  Australia   India   40   Guandong,  China   35   30   25   20   15   10   5   0   Lanthanum   Cerium   Praseodymium   Neodymium   Samarium   Figure 4: Contents of the main rare earth elements in monazite for three deposits (Kingsnorth 2010) 2.2.3. Xenotime Xenotime is a phosphate which is composed primarily of yttrium (YPO4). This mineral contains generally around 55% of REO. Moreover, it contains a particularly high rate of heavy REEs which makes it valuable. This mineral occurs usually in rocks that also contain uranium and thorium. Historically, it was produced as a by-product of tin mining in Malaysia, Indonesia and Thailand (Alex et al. 1998; Roskill 2007) Figure 5 illustrates the abundance of the main REEs in xenotime. 70   %  among  rare  earths  in  xenotime   Lahat  Perak,  Malaysia   60   Guangdong,  China   50   40   30   20   10   0   Figure 5: Contents of the main rare earth elements in xenotime (Kingsnorth 2010)20
    • 2.2.4. Ion Adsorption Clays These minerals are peculiar to the Jiangxi province of southern China. They are theresult of the weathering of two minerals: xenotime and apatite. Although they have a very small content of REEs (0.05% to 0.2%) (Kanazawa andKamitani 2006), these clays are particularly interesting because they contain relativelyhigh contents of heavy REEs compared to other rare earth minerals. (Roskill 2007;Kingsnorth 2010). Another advantage of these minerals is that they can be easily mined andprocessed4. Besides, they contain very few radioactive elements (Kanazawa and Kamitani2006). However, as illustrated in the following figure, even though they come from thesame geographical area, their contents of REEs vary significantly. Figure 6 illustrates the abundance of the main REEs in ionic clays. 70   Xunwu,  Jiangxi,  China   %  among  rare  earths  in  ionic  clays   60   Lognan,  Jiangxi,  China   50   40   30   20   10   0   Figure 6: Contents of the main rare earth elements in Chinese ionic clays (Kingsnorth 2010) 4 The processing of ion adsorption clays does not require any milling and REOs areproduced by a simple method (Kanazawa and Kamitani 2006). 21
    • 2.3. Description of the rare earth reserves In 2011, it was estimated that the total recoverable resource amounts approximately 140 Mt (USGS 2011). The economically viable reserves of REEs are summarised in Figure 7. Australia   Brazil   1.6  Mt   48,000  t   1%   0%   United  States   Other  countries   13  Mt   22  Mt   12%   19%   Malaysia   30,000  t   China   0%   55  Mt   48%   India   3.1  Mt   3%   Commonwealth  of   Independent   States   19  Mt   17%   Figure 7: Breakdown of the economically viable rare earth resource (USGS 2011) 2.4. Historical production of rare earth oxide REOs were first produced in the 1880s with the mining of monazite in Sweden and Norway. Their first industrial application was in the Welsbach incandescent lamp mantle in 1884. The production of REOs in the USA began in 1903 with the mining of monazite in South Carolina. Over the first half of the last century, the production remained quite low. It then increased due to the discovery of new applications such as catalysts to crack crude oil into petroleum. Until the 1960s, the production of REEs from placer monazite took mainly place in the southeast of the USA. It was then abandoned due to its high content of thorium (Hedrick 2000). Then, the production moved to a major deposit located at Mountain Pass, California. This mine was in operation from 1965 until the mid 1990s and over this period only bastnaesite was processed in Mountain Pass. At Mountain Pass, the reserves of REEs are still over 20 million tonnes with an average grade of rare earth minerals of 8.9% (Castor and Hedrick 2006). Through the 1990s, China’s exports grew importantly causing American production to be undercut. Most of the Chinese production comes from Bayan Obo deposit (Inner Mongolia, China) which represents the largest known REE resource in the world. In this22
    • mine, both bastnaesite and monazite are processed (Castor and Hedrick 2006; Hurst2010). Figure 8 illustrates the growth in the production of REOs over the 20th century. 160,000   140,000   120,000   Production  (tonne)   100,000   80,000   60,000   40,000   20,000   0   1900   1910   1920   1930   1940   1950   1960   1970   1980   1990   2000   Figure 8: Global production of rare earth oxide (USGS 2010) Figure 9 illustrates the great periods of REE exploitation from 1950. Figure 9: World production of rare earth oxides from 1950 to 2000 (Haxel 2002) 23
    • 2.5. Description of the main applications of the rare earth elements This section is entirely based on the two following works: - Roskill 2007 - Schüler et al. 2011 Figure 10 describes the world demand of REEs in 2006. Other   8%   Phosphors   9%   Catalyst   21%   Magnets   20%   Glass,  Polishing,   Ceramics   25%   Metal  Alloys   17%   Figure 10: Global rare earth consumption in 2006 (Roskill 2007) 2.5.1. Magnets There are two main kinds of rare earth magnets: neodymium-iron-boron magnets and samarium-cobalt magnets. Neodymium-iron-boron (Nd2Fe14B) magnets are the strongest available magnets. In addition to neodymium, they comprise other REEs: praseodymium (30% the amount of neodymium) and dysprosium (3% the amount of neodymium). This market is growing very quickly since its average annual growth was 25% between 1986 and 2006. This growth is driven by three main applications: electric motors for hybrid and electric vehicles, generators in wind turbines and computer hard disks. Moreover, several other applications requires neodymium magnets such as: - loudspeakers, earphones and microphones - MRIs scanners - electric bicycles24
    • 2.5.2. Catalyst REEs are used as catalysts in the automobile industry, petroleum refinery andchemical processing. REEs are use for the following applications: - automotive catalysts and diesel additives (cerium) - fluid cracking catalyst for the petroleum industry (cerium, lanthanum) In the automobile industry, cerium is used to: - reduce nitrogen oxide into nitrogen and water - oxide CO to CO2 2.5.3. Glass, polishing, ceramics 2.5.3.1. Glass polishing Thanks to its specific properties of physical and chemical abrasion cerium ismassively used to produce high-quality glass for the following markets: - mirrors - televisions and monitors - panel displays - glass platters in hard disks This sector represents 13% of the global REE consumption. Its growth rate followsthat of plasma displays, LCDs and computer monitors. 2.5.3.2. Glass additives REEs are used as glass additives for the following applications: - colouring of glass (cerium for yellow and brown, neodymium for red, erbium for pink) - decolouring of glass (cerium) - UV-resistant glass (e.g. for glass bottles, sunglasses, solar cells) (cerium) - optical lenses, filters or coating (lanthanum, gadolinium, praseodymium) This sector represents 12% of the global REE consumption. The growth of thismarket is mainly driven by the growth in optical applications (e.g. digital cameras,security cameras, mobile phones). 2.5.3.3. Ceramics REEs are used in ceramics for the following applications: - ceramic capacitors and semiconductors (lanthanum, cerium, praseodymium, neodymium) - superconductors (yttrium) - dental ceramics (cerium) - refractory materials (cerium, yttrium) - laser (yttrium) This sector represents 5% of the global REE consumption. The growth of electronics results in an increase of the demand of REEs for ceramicuses. 25
    • 2.5.4. Metal alloys REEs are used in metal alloys for different applications. They bring new properties to the metal they are mixed with. They can be used in: - pyrophoric alloys (cerium, lanthanum) - high-performance alloys to improve their performances (lanthanum, cerium, yttrium) - solid state storage of hydrogen in metallic matrixes - scandium-aluminium alloys used in military aviation - lanthanum-nickel alloys in Ni-MH batteries 2.5.5. Phosphors and luminescence REEs are inserted into crystals of various natures in order to give them luminescence properties. Depending on the wavelength expected, it is possible to choose between cerium, samarium, europium, gadolinium, terbium, dysprosium, erbium, thulium or lutetium. As a result, these REEs are used in mainly two fields: energy saving lighting and display technologies. They are found in the following applications - compact fluorescent lamps (energy saving lamps) - fluorescent tubes - LEDs and OLEDs - electroluminescent foils - plasma displays - LCDs The growth in this sector is driven by: - the general growth in the lighting demand (7% per year from 2004 to 2011) - the replacement of incandescent bulbs in many countries by among other compact fluorescent lamps and halogen lamps - the growth of the LED market - the replacement of cathode-ray tubes by plasma displays and LCDs 2.5.6. Other Many other applications require REEs: - agricultural use of REEs in phosphate fertiliser (cerium, lanthanum) - Ni-MH batteries (lanthanum, cerium, neodymium, praseodymium) - solid oxide fuel cell electrolytes (yttrium) - neutron absorbers in nuclear reactors (europium, gadolinium) - waste water treatment (cerium)26
    • 3. Production of rare earth elements 3.1. World production of rare earth elements Since the end of the 1990s, China has been the main producer of REEs in the world.In 2010, its official production amounted to 130,000 tonnes of REOs while the secondand third largest producers (respectively India and Brazil) produced, respectively, 2,700tonnes and 550 tonnes of REOs (USGS 2011). As a result, the main REE mines and processing plants are to be found in China. Figure 11 summarises the global production of REEs: Brazil   550  t   1%   Malaysia   350  t   China   India   0%   130,000  t   2,700  t   97%   2%   Figure 11: Global production of rare earth oxides in 2010 (USGS 2011) 3.2. Chinese production of rare earths The Chinese production of REEs takes place in three different areas: InnerMongolia, Sichuan province, and seven southern provinces. 3.2.1. Inner Mongolia Inner Mongolia houses the largest deposit of REEs in the world, namely Bayan Obodeposit. It accounts for 80% of the Chinese reserve of REEs (Crédit Suisse 2011; Schüleret al. 2011). However, it appears that the precise amount of the REO resources contained in thisdeposit varies according to the measurement method: the reserve ranges from 28 milliontonnes of REO (USGS classification) to 44 million tonnes (Chinese classification) (CréditSuisse 2011). The definitions of the different classifications are given in Appendix 1. In Bayan Obo, REOs are produced as a by-product of iron ore whose reserveamounts to 1.46 billion tonnes (Spooner 2005; Roskill 2007). The REOs mined in Bayan Obo are composed primarily of light REEs thatrepresent 97% of the whole rare earth minerals. The rare earth minerals are concentratedin two different minerals: bastnaesite and monazite (there is about 2.5 as much bastnaesiteas monazite) (Huang et al. 2005; Crédit Suisse 2011). 27
    • Figure 12 illustrates the composition of rare earth mineral in Bayan Obo’s ore. Figure 12: Breakdown of rare earth oxide-content at Bayan Obo (Crédit Suisse 2011) This deposit is owned by one state-owned company called Baotou Steel Rare Earth Group Hi-Tech Co, Ltd (Baotou Rare Earth). It is a fully integrated company (from mining operations to the production of REOs). Besides, the Chinese Ministry of Land and Resources has decided to restructure the industry of REE production in Inner Mongolia. As a result, Baotou Rare Earth will soon become the only company extracting and producing REEs from the Bayan Obo deposit (Crédit Suisse 2011; Global Times 2011). In 2010, Baotou Rare Earth produced 62,400 t of REO (Crédit Suisse 2011). 3.2.2. Sichuan province The second largest deposit of bastnaesite mineral in China is located in the county of Mianning (Sichuan Province). This deposit is called Maoniuping after the name of a surrounding city. It is estimated to contain 3% of Chinese reserves of REO. This represents 1.56 Mt of REOs according to the Chinese classification (Crédit Suisse 2011; Schüler et al. 2011). In this deposit, rare earth minerals are contained almost exclusively in bastnaesite (Tse 2011). Since Bayan Obo’s ore is composed of approximately 70% bastnaesite, the content of REEs in the Maoniuping’s ore is quite similar to Bayan Obo’s.28
    • Figure 13 illustrates the composition in REEs of the bastnaesite in Maoniuping: Figure 13: Bastnaesite content of rare earth elements at Maoniuping (Spooner 2005) The REO production in Maoniuping accounts for 24% of China’s total production,i.e., approximately 31,200 tonnes, in 2010 (Crédit Suisse 2011; Tse 2011; Wong and Li2011). As in Bayan Obo, the mining operations are controlled by a single company namedJiangxi Copper (JXC Group) (Crédit Suisse 2011). 3.2.3. Southern Provinces The seven southern provinces that contribute to the production of Chinese REEsare: Jiangxi, Guangdong, Fujian, Guangxi, Hunan, Yunnan and Zhejiang. They representthe majority of China’s production of heavy REEs (Crédit Suisse 2011). In these provinces, REEs are found in ionic clays which are composed at 90% ofheavy REEs. Figure 14 illustrates the content of ionic clay. Figure 14: Ionic clay content of rare earth elements at Longnan (Crédit Suisse 2011) 29
    • The production of REEs from Chinese ionic clays was approximately 36,000 tonnes in 2010 representing 28% of the China’s REE production (Crédit Suisse 2011; Tse 2011). 3.2.4. Summary of Chinese rare earth production Figure 15 was drawn to summarise the information in the previous sections. It shows the distribution of the REE production between the different Chinese regions. Maoniuping   24%   Bayan  Obo   48%   Southern   Provinces   28%   Figure 15: Distribution of the Chinese production of rare earths in 2010 Light REEs account for 72% of Chinese REE production. Since Chinese production amounted to 97% of the global production, light REEs represented at least 70% of the REEs produced globally in 2010. As a result, since the production of light REEs from bastnaesite takes place only in Bayan Obo and in Sichuan province, these two regions will be subsequently analysed. 3.3. Prospective other productions In response to the introduction of quotas by the Chinese government and the increase in REE prices, western companies have launched important projects that aim at supplementing the Chinese production. Among these projects, two are particularly significant because: • they are both very large (production > 20,000 tonnes of REOs per year) • they are in the final stages of development and, are planned to open in the next two years 3.3.1. Mount Weld, Australia Mount Weld is located in southwestern Australia. This deposit is own by Lynas Corporation Ltd which is an Australian REE mining company. Mount Weld is estimated to include 1.4 Mt of REO contained mainly in monazite (i.e. composed primarily of light REEs) (Crédit Suisse 2011).30
    • purification of REEs) will be carried out in Malaysia by a subsidiary of Lynas (LynasMalaysia). The production will start at 11,000 t of REO p.a. and increase up to 22,000 t of REOp.a (British Geological Survey 2011; Schüler et al. 2011). 3.3.2. Mountain Pass, USA Mountain Pass is the deposit from which the REEs were historically produced forseveral years. It was undercut by the Chinese production in the 1990s and was notoperating since then. Mountain Pass contains 4.3 Mt of REO in bastnaesite minerals. It is now own by a company named Molycorp which plans to reopen the mines in2012. Like Lynas in Australia, Molycorp will produce 20,000 t p.a. when operating at fullcapacity. Thanks to the existing facilities, the mining and the processing will be carriedout on the same site (Hurst 2010; British Geological Survey 2011; Crédit Suisse 2011;Schüler et al. 2011). 31
    • 4. Scope refining To limit the scope of this project, it was decided to focus only on the production of light REEs since they account for the majority of world REE production. Since Chinese production represented 97% of 2010 global production, it was decided that concentrating on this production would give an accurate perspective of the present environmental impacts of producing light REOs. Finally, as explained in section 3.2.4, China’s light REEs come only from two deposits: Bayan Obo and Maoniuping. As a result, the scope of the study was defined to the assessment of environmental impacts of producing light REO in both Bayan Obo and Maoniuping deposits. 5. Bayan Obo deposit 5.1. Description of the deposit The Bayan Obo deposit (Inner Mongolia, China) is located 80 km south of the Mongolian border. The principal ore minerals are bastnaesite and monazite (rare earth minerals), pyrochlore (Nb), magnetite and hematite (Fe) (Campbell and Henderson 1997). In Bayan Obo, REEs were produced from more than twenty sites since the beginning of the mining in 1957. The two largest deposits are the Main and East ore bodies with a REE grade of 5.14% and 5.18% respectively5. The Bayan Obo ore is hosted in dolomite (Castor and Hedrick 2006). The mining operations are carried out using electric shovels and rail haulage at a rate of 15,000 tonnes of rock per day from the two large open pits (Castor and Hedrick 2006). 5.2. Composition of the original ore Baotou’s rock is complex and its composition varies significantly from one place to another. Therefore it is not possible to give the composition of this ore in general. However, it is possible to look at some specific elements (Drew et al. 1990; Castor and Hedrick 2006): - iron: average grade of 35% - REOs: average grade of 6% - niobium: average grade of 0.13% - fluorite (CaF2): average grade of 9% - barium oxide (BaO): average grade of 2.4% 5.3. Description of the beneficiation process The beneficiation process is described in Table 2. For each stage of this process, a description is given as well as the sources of the information. 5 These grades are surprisingly lower than the average rare earth grade (6%), this may be because in Bayan Obo, REO are produced as a by-product of iron.32
    • Table 2: Beneficiation process in Bayan Obo Stage   Purpose   Process  description   Reference   o Schüler et al. 2011 o Cheng et al. 2007 Crushing   • Crushing of 90% of the • The ore is crushed and ground in a mill o Guy et al. 2000 resulting particles to < 74 µm o Ren et al. 1997 o Drew et al. 1990 • Recovery of silicates and iron minerals (magnetite Fe3O4 and hematite Fe2O3) from the bottom of the flotation cell for ion beneficiation and niobium recovery Bulk   • Separation of rare earth minerals • pH regulation by Na2CO3 o Gupta and Krishnamurthy 2005 flotation6   and the gangue from the other valuable minerals • Depressant action by Na2SiO3 • Collection of rare earth minerals and gangue by sodium salt of oxidised petroleum (paraffin soap) • Removal of the surplus paraffin - o Hout, et al. 1991 Thickening   soap and desliming at 5 µm o Gupta and Krishnamurthy 2005 • pH regulation by Na2CO3 Selective   • Separation of rare earth minerals o Gupta and Krishnamurthy 2005 • Depressant action by Na2SiF6 and Na2SiO3 rare  earth   from calcite (CaCO3), fluorite o Ren, et al. 2003 (CaF2) and barite (BaSO4) • Collection of rare earth minerals by hydroxamic acid flotation6   (paraffin soap) o Ferron, et al. 1991 minerals o Gupta and Krishnamurthy 2005 Cleaning   • Concentration of rare earth • Thickening, filtering and drying of the resulting slurry o British Geological Survey 2010 minerals o Wang, et al. 2010 6 The flotation process is described further in Appendix 233
    • 5.4. Composition of the mixed rare earth concentrate Figure 16 illustrates the composition of the mixed rare earth concentrate obtained after the beneficiation process. MnO   0.48%   CaO   5.11%   CO2   SiO2   11.91%   1.28%   P2O5   8.22%   F   REO   6.96%   60.94%   Fe2O3   4.82%   ThO2   0.18%   Figure 16: Composition by weight of the mixed bastnaesite-monazite concentrate (Wang et al. 2002) 5.5. Processing of the mixed rare earth concentrate 5.5.1. Hydrometallurgy: acidic method An acidic method is used to process 90% of the product of Bayan Obo. It consists in the roasting and leaching of the concentrate with sulphuric acid (Schüler et al. 2011). Table 3 summarises the hydrometallurgy processes at Bayan Obo. 5.5.1. Separation and refining Table 4 describes the processes of separation and refining leading to the production of REOs. 5.6. Obtaining of rare earth oxides A tonne of REOs produced in Bayan Obo is composed as described in Figure 17.34
    • Table 3: Processing of mixed rare earth concentrate in Bayan Obo Stage   Purpose   Process  description   Reference   • Mixing of rare earth concentrate and 98% sulphuric acid (H2SO4) in a rotary kiln at 500°C for 4 hours. o Schüler, et al. 2011 • Removal of CO2, • Reactions for bastnaesite: o Huang, et al. 2005 Sulphatising   phosphate and fluoride ReFCO3  ReFO + CO2 • Conversion of rare o Gupta and Krishnamurthy 2005 roasting   2 ReFO + 3 H2SO4Re2(SO4)3 +2 HF +2 H2O earth minerals into rare o Nguyen, et al. 2002 earth sulphates • Reactions for monazite: o Wang, et al. 2010 2 RePO4 + 3 H2SO4  Re2(SO4)3 + 2 H3PO4 o Todorovsky, et al. 1993 • Decantation of the mixture to remove the solid o Roskill 2007 Removal  of   • Filtration and leaching with water o Schüler, et al. 2011 impurities   • Removal of impurities • Obtaining of a pure rare earth sulphate solution o Kul, et al. 2008 o Nguyen, et al. 2002 o Gupta and Krishnamurthy 2005 • Rinsing of rare earth sulphates with bicarbonates o Nguyen, et al. 2002 • Selective precipitation Carbonate   and recovery of the rare NH4HCO3 in an acid solution: o Schüler, et al. 2011 precipitation   earth sulphates into Re2(SO4)3+ 6 NH4HCO3  Re2(CO3)3 + 3 (NH4)2SO4 o Kul, et al. 2008 + 3 CO2 + 3 H2O o Abreu and Morais 2010 carbonate precipitate • Transformation of rare • Rinsing with hydrochloric acid (HCl) Acid   earth carbonate • Transformation to rare earth chlorides: o Schüler, et al. 2011 leaching   precipitate into rare earth Re2(CO3)3 + 6 HCl  2 ReCl3 + 3 H2CO3 o Huang, et al. 2005 chlorides35
    • Table 4: Separation and refining processes in Bayan Obo Step   Purpose   Process  description   Reference   • The liquid-liquid extraction is carried out using 2- ethylhexylphosphonic acid mono-2-ethylhexyl ester (also named HEH(EHP), EHEHPA or P 507) in a HCl medium. o Schüler, et al. 2011 Solvent   • Separation of REEs • Complexation reaction: o Fontana and Pietrelli 2009 Extraction7   from each other Re3+ + 3 (HX)2  ReX6H3 + 3 H+ o Sato 1989 HX referring to P507 • The separated rare earth solution is precipitated by • Separation of rare ammonium bicarbonate (NH4)HCO3 or oxalic acid C2H2O4 o Qiu, et al. 2010Precipitation   earth complexes from • Chemical reactions: o Schüler, et al. 2011 the solvent 2 ReCl3 + 3 C2H2O4  Re2(C2O4)3 + 6 HCl • The precipitates are heated in order to oxidise them intoProduction  of   • Oxidation of the REO • Oxidation reaction: o Schüler, et al. 2011 REO   precipitate Re2(C2O4)3 + 3/2 O2  Re2O3 + 6 CO2 8 7 The solvent extraction process is described further in Appendix 3 8 The oxidation reactions depend on the rare earth concerned: - for La, Nd and Sm: Re2(C2O4)3 + 3/2 O2  Re2O3 + 6 CO2 - for Ce: Ce2(C2O4)3 + 2 O2  2 CeO2 + 6 CO2 - for Pr: 3 Pr2C2O4 + 11/2 O2  Pr6O11 + 6 CO236
    • La2O3   235.4  kg   Pr6O11   51.2  kg   Nd2O3   CeO2   184.2  kg   512.8  kg   Sm2O3   16.4  kg   Figure 17: Composition of a tonne of rare earth oxides produced from Bayan Obo ore (Spooner 2005)6. Maoniuping deposit 6.1. Description of the deposit Maoniuping deposit is located at 22 km southwest of the Mianning county town(Sichuan Province, China). The soil is composed mainly of granite (K-feldspar graniteand alkali feldspar granite). Among rare earth minerals, bastnaesite is the most important in this deposit(Wu et al. 1997). The average grade of REEs in this deposit is about 4%. This depositcontains also manganese (Mn) (2-10%), lead (Pb) and aluminium (Al) among otherminerals (Zhu et al. 2000). Maoniuping is the second largest deposit of light REEs in China after Bayan Obo(Xu et al. 2003). 37
    • 6.2. Composition of the original ore Figure 18 illustrates the composition of the ore in Maoniuping deposit. TiO2   SO3   0.28   3.9   BaO   Al2O3   1.89   16.3   CaO   1.3   CO2   SiO2   3.77   36   F   Fe2O3   1.29   11   Rare  earths   H2O   4.34   6.22   Pb   K2O   1.97   MnO   3.89   3.78   P2O5   Na2O   MgO   0.64   0.4   3.03   Figure 18: Composition of the ore in Maoniuping’s mineral (Zhu et al. 2000) 6.3. Description of the beneficiation process The process of beneficiation in Maoniuping is described in Table 5.38
    • Table 5: Beneficiation process in Maoniuping Step   Purpose   Process  description   Reference   • Reduction of the size of the particles so • The ore is crushed and ground in a mill o Schüler, et al. 2011 Crushing   as to increase the o Zhu, et al. 2000 surface of reaction Gravity   • Separation and o Schüler, et al. 2011 - separation   recovery of certain o Yang and Woolley 2006 valuable minerals Selective  rare   • Separation of rare - o Schüler, et al. 2011 earth  flotation   earth minerals from the gangue • The resulting slurry is thickened, filtered and dried o Gupta and Krishnamurthy 2005 • Recovery of rare • The overall recovery of REEs lies between 80 and o British Geological Survey 2010 Cleaning   earth concentrate 85% and the concentrate contains up to 70% REEs o Wang, et al. 2010 o Li and Zeng 200339
    • 6.4. Processing of the mixed rare earth concentrate 6.4.1. Hydrometallurgy: acidic method Table 6 summarises the hydrometallurgy processes at Maoniuping. 6.4.2. Separation and refining operations The separation and refining operations in Maoniuping are the same as those in Bayan Obo (see 5.5.1) (Schüler et al. 2011). 6.5. Obtaining of rare earth oxides A tonne of REOs produced in Maoniuping is composed as described in Figure 19. La2O3   296.1  kg   Pr6O11   CeO2   46.7  kg   510.1  kg   Nd2O3   131.8  kg   Sm2O3   15.2  kg   Figure 19: Composition of a tonne of rare earth oxides produced from Maoniuping ore (Spooner 2005)40
    • Table 6: Processing of rare earth concentrate in Maoniuping Step   Purpose   Process  description   Reference   • The concentrate is mixed with 98% sulphuric acid o Schüler, et al. 2011 • Removal of CO2 (H2SO4) in a rotary kiln at 500°C for 4 hours o Huang, et al. 2005 Sulphatising   and fluoride • Reactions: o Nguyen, et al. 2002 roasting   • Conversion of rare ReFCO3  ReFO + CO2 o Wang, et al. 2010 earth minerals into ReFO + H2SO4Re2(SO4)3 +2 HF +2 H2O o Gupta and Krishnamurthy 2005 rare earth sulphates • The mixture is decanted to remove the solid o Todorovsky, et al. 1993 • The solution is filtered and leached with water o Roskill 2007 Removal  of   • Removal of • A pure rare earth sulphate solution is obtained (this o Schüler, et al. 2011 impurities   impurities solution contains around 40g/L of rare earth o Kul, et al. 2008 sulphates) o Nguyen, et al. 2002 o Gupta and Krishnamurthy 2005 • Selective • REEs are leached with sodium sulphates (at o Nguyen, et al. 2002 Sulphate   precipitation and pH 1.5) o Schüler, et al. 2011 precipitation   recovery of the rare • Precipitation reaction: o Kul, et al. 2008 earth sulphates into Re3+ +Na+ + 2 SO42-  NaRe(SO4)2 o Abreu and Morais 2010 sulphate precipitate • Rare earth carbonates are leached with hydrochloric acid (HCl) • Transformation of • The carbonates are transformed to rare earth o Schüler, et al. 2011 Acid  Leaching   rare earth carbonate chlorides precipitate into rare o Huang, et al. 2005 earth chlorides • Chlorination reaction NaRe(SO4)2 + HCl  ReCl3 + Na+ + 3 H+ + 2 SO42-41
    • Life Cycle assessment (LCA) 7. Life cycle assessment methodology A cradle-to-gate methodology rather than full cradle-to-grave life cycle assessment (LCA) was used since it allowed restriction of the scope of this study. The cradle to gate approach defines the boundaries as “from raw material to factory gate”. In this case, it was indeed from raw material to REO output, without consideration of the fate of the numerous products made with REEs. In conformity with LCA methodology, this LCA is composed of the following sections: - Goal and Scope definition - Life Cycle Inventory - Life Cycle Impact Assessment - Life Cycle Interpretation Firstly, the goal and scope section exposes the reasons why the LCA is carried out as well as defines the boundaries of the LCA. Secondly, the life cycle inventory aims at determining the inputs and outputs of material or energy that are required by the different processes. This phase is based on a meticulous modelling of these processes. Thirdly, the life cycle impact assessment classifies and characterises the results of the life cycle inventory to come up with a quantitative estimate of environmental impacts. Finally, the life cycle interpretation draws conclusion on the LCA based on the three first steps. It helps analysing the results as well as the gaps in the study. 8. Goal definition and scope 8.1. Goal of the life cycle assessment The goal of the LCA is to establish baseline information for the processes taking place in the two biggest deposits of light REEs and resulting in the production of REO. This baseline consists of energy and chemical requirements, waste generation and pollution. This study should be looked at as starting points for people aiming at: - carrying out the full life cycle assessment of lanthanum, cerium, praseodymium or neodymium products - studying the environmental impacts of a product containing these REEs - studying the two deposits that are scrutinised here - carrying out a similar study for a different mineral - gaining knowledge about REEs The intended audience is whoever is interested in the requirements and impacts of producing REOs.42
    • 8.2. Level of specificity Although this study focuses precisely on two mines, it uses specific data whenavailable and average data otherwise. Due to the lack of available information, a highlevel of accuracy is not to be expected. The results should rather be considered as givingrealistic orders of magnitude of the energy and chemical consumption, waste generationand pollution emissions. 8.3. Display of results Throughout the LCA, the results are expressed “per tonne of REOs” (except whereotherwise stated). This means that the amounts are estimated for a final production of onetonne of REO. 8.4. Scope of the life cycle assessment The study is not a full life cycle assessment, it is composed of two stages: rawmaterial acquisition and materials manufacture. It focuses on the mining, beneficiationand refining operations to obtain REOs. These boundaries are in accordance with thescope defined in section 4. Besides, the study takes into consideration only primary activities that contribute toextracting and transforming the mineral. It does not considerate activities that contributeto making the primary activities possible. 8.5. Guideline to life cycle assessment methodology In order to carry out this study according to international standards, a mainguideline was followed as meticulously as possible: - Life cycle assessment: principles and practice by the U.S. Environmental Protection Agency (Curran 2006)9. Process Modelling: The processes described in the previous sections were modelled in order to calculatethe amount of inputs and outputs required by the production of REOs. In order to simplify the understanding, the processes of Bayan Obo were firstlymodelled and then the processes of Maoniuping were modelled. 9.1. Bayan Obo deposit The calculations are explained in Appendix 4. 9.1.1. Mining On the one hand, there are two different kinds of inputs: energy to fuel themachinery and explosives. On the other hand, there are two different types of outputs:valuable minerals and waste rocks. Before modelling the mining operation, consideration is given to the mining rate. The results and assumptions are summarised in Table 7. 43
    • 9.1.1.1. Mining rate The mining rate is the rate of rock extraction, it is expressed in tonnes per day (tpd). Assuming that mining rate in the Bayan Obo deposit increased proportionally to the REO production, the mining rate of 15,000 tonnes per day (tpd) in 2006 (Castor and Hedrick 2006) can be used to estimate the mining rate in 2010. As a result, it is estimated that the Bayan Obo mining rate was about 16,200 tpd in 2010. 9.1.1.2. Energy requirement Due to a lack of public data, it was not possible to estimate the energy consumption of the mining operations directly. However, the order of magnitude of the energy consumption is provided in the Mining Engineering Handbook, which estimates that surface mining operations require 5 to 10 kWh per tonne of rock handled (Nilsson 1992). Thus, considering 7.5 kWh per tonne of rock handled (middle figure between 5 and 10 kWh), it is estimated that the annual quantity of energy consumed in the mining operations amounts to 44.3 GWh. Assuming that the mining operations are carried out with machinery (trucks, shovel…), this amount of energy is provided with fuel. 9.1.1.3. Explosives input In the same document, Nilsson estimates that surface mining operations requires 0.14 to 0.23 kg of ammonium nitrate/fuel oil (ANFO) 9 per tonne of blasted rock (Nilsson 1992). Assuming that the mining operations requires 0.2 kg of ANFO per tonne of blasted rock, the annual quantity of ANFO for the mining operations is about 1,180 tonnes. 9.1.2. Comminution This stage of the operations does not require any input but energy to grind and crush and the rock to be ground and crushed. The only output is the crushed rock. The energy requirements are estimated based on a similar rare earth mining project. This project takes place in Thor Lake (Northwest territories of Canada), it is supposed to start the production not before 2014. The company Avalon Rare Metals is carrying out this project (Eriksson and Olsson 2011). Avalon Rare Metals has estimated that 6 MW are necessary in average for the 2,000 tpd milling operations (comminution, beneficiation and hydrometallurgy) (Cox et al. 2011). As a result, it is estimated that the comminution, beneficiation and hydrometallurgy operations in Bayan Obo require 426 GWh per year. The results and assumptions of the mining and comminution sections are summarised in Table 7. 9 ANFO is an explosive composed of ammonium nitrates (NH4NO3) and oil.44
    • 9.1.3. Beneficiation During the production of concentrated bastnaesite, several different chemicals areused to obtain the right froth flotation. Unfortunately, it was not possible to identify thedifferent chemicals nor to determine how long these solutions can be used before beingdiscarded. However, two main other inputs have been identified for this stage: energy for thechemical reactions and mined minerals. The outputs are of three different types: - rare earth concentrate - other valuable minerals (such as those containing Fe or Nb) - tailings Assuming a full recovery and high selectivity of the magnetic minerals (Fe and Nb)thanks to the magnetic separation roll, the beneficiation process is described in Figure 20. 45
    • 46 Table 7: Summary of the mining and comminution processes modelling Stage   Type   Quantity   Assumptions   o proportionality to REO output o Bayan Obo represented 48% of Mining   Mining rate 16,200 tpd the production in 2006 (as in 2010)   Energy requirement 44.3 GWh per year o mining rate assumption   Explosives 1,180 tonnes per year o mining rate assumption Comminution,  Beneficiation  and   o proportionality to Thor Lake Energy requirement 426 GWh per year Hydrometallurgy   project Table 8: Summary of the beneficiation modelling Stage   Type   Quantity   Assumptions   o 75% efficiency of the Beneficiation   Rare earth concentrate produced 139,000 tonnes per year subsequent stages o 60% recovery of REEs o Full recovery and perfect 9.8 tonnes per tonne of rare earth   Waste rock generated selectivity of Fe and Nb concentrate produced minerals
    • Nb   1.3  kg   0%   35.1 % Fe   350  kg   Magnetic minerals 100%   Fe   6% Rare   350  kg   Earth   35%   36  kg   Gangue   60%   24  kg   Rare earth 40%   Gangue   concentrate 588.7  kg   59%   Rare   Rare   Earth   Gangue   Earth   60  kg   564.7  kg   24  kg   6%   96%   4%   Nb   58.9 % 1.3  kg   0%   Tailings Figure 20: Beneficiation process in Bayan Obo for one tonne of original rock As a consequence, the processing of one tonne of original ore results in theproduction of: - 351 kg of iron and niobium (recovered to be later refined) - 60 kg of mixed rare earth concentrate - 589 kg of tailings Considering the production of REO in 2010 (62,400 t) and assuming a 75%efficiency of the overall subsequent stages (Schüler et al. 2011), it is estimated that139,000 tonnes of mixed-rare earth concentrate were produced that year. The results and assumptions of the beneficiation process are summarised in Table 8. 9.1.4. Hydrometallurgy and separation of rare earths This stage was described in section 5.5. It is composed of several successivechemical reactions. 47
    • For both deposits, the overall recovery rate of the separation and refining processes is considered to be 75% (Schüler et al. 2011). It is considered that the five different chemical reactions each have the same recovery rate rR: ! !! =   !. 75 = 94.4% Considering that the bastnaesite/monazite ratio was 5:2 (71.4% of bastnaesite and 28.6% of monazite in Bayan Obo’s rare earth mineral) (Huang et al. 2005), each chemical reaction was scrutinised to estimate how much of every chemical is required per rare earth atom. This is described in the following section: Chemical reactions ReFCO3 RePO4 0.71 CO2 For bastnaesite: 3/2 H2SO4 0.71 HF ReFCO3  ReFO + CO2 Acidic roasting Heat 0.71 H2O 2 ReFO + 3 H2SO4 Re2(SO4)3 0.29 H3PO4 + 2HF+2 H2O For monazite: Re2(SO4)3 2 RePO4 + 3 H2SO4  Re2(SO4)3 + 2 H3PO4 3/2 (NH4)2SO4 Carbonate3 (NH4)HCO3 3/2 CO2 Re2(SO4)3+ 6 (NH4)HCO3  precipitation 3/2 H2O Re2(CO3)3 +3 (NH4)2SO4 + 3 CO2 + 3 H2O Re2(CO3)3 3 HCl Acid leaching 3/2 H2CO3 Re2(CO3)3 + 6 HCl  2 ReCl3 + 3 H2CO3 ReCl3 Heat Solvent extraction 3 (HX)2 ReCl3 + 3(HX)2  ReX6H3 + 3 HCl 3 (HX)2 ReX6H3 + 3 HCl  ReCl3 + 3(HX)2 48
    • The stoichiometric coefficients for the hydrometallurgy process are summarised in Table 9. 9.1.5. Refining Likewise, the estimation of the amounts of necessary chemicals for the refining process was carried out based on the different chemical reactions. ReCl3 Chemical reactions 2 ReCl3 + 3 C2H2O4  Re2(C2O4)3 +3/2 C2H2O4 Precipitation 3 HCl 6 HCl Re2(C2O4)3 Re2(C2O4)3+ 3/2O2 Re2O3+ 6 CO2 for Heat Oxidation 3 CO2 La, Nd & Sm 0.93 O2 Re2(C2O4)3+ 2 O2  2 ReO2 +6 CO2 for Ce 3 Re2(C2O4)3+11/2O2Re6O11+18CO2 Rare earth oxide for Pr The stoichiometric coefficients for the refining process are summarised in Table 9. 9.1.6. Stripping ratio The stripping ratio is the ratio between the mass of waste rock that is generated and the mass of mineral that goes for further processing. The calculation of the stripping ratio is composed of three steps. Firstly, the yearly mass (mY) recovered in Bayan Obo deposit in 2010 is calculated from the mining rate of the mine: !! = 16,250 ∗ 365 = 5.93  10!  !"##$% Then, the mass of mineral (mM) that is processed is calculated from the rare earth grade of the mineral rate (6%), the production of REO in 2010 (62,400 t), the beneficiation recovery (60%) and the recovery during subsequent processes (75%): !"#  !"#$%&(#)!"#! !! =   = 2.31  10! !"##$% !"#"$%&%(%)#!"#$%"!& ∗ !"#$%$%&!"#$%"!& ∗   !"#$  !"#$ℎ!"#$% Finally, the mass of waste recovered (mWaste) is calculated: !!"#$% = !! − !! = 3.62  10!  !"##!" As a result, the stripping ratio in Bayan Obo is estimated: !!"#$% !"#$%%$&  !"#$% = = 1.57 !! For each tonne of mineral that is processed in the early stages, 1.57 tonne of waste are recovered. 49
    • Table 9: Summary of the stoichiometric coefficients in Bayan Obo Stage   Chemical   Type:  Input/Output   Stoichiometric   (I/O)   coefficient   Hydrometallurgy   H2SO4 I 1.5 Hydrometallurgy   (NH4)HCO3 I 3 Hydrometallurgy   HCl I 3 Hydrometallurgy   CO2 O 2.21 Hydrometallurgy   H2 O O 2.21 Hydrometallurgy   H2CO3 O 1.5 Hydrometallurgy   H3PO4 O 0.29 Hydrometallurgy   (NH4)2SO4 O 1.5 Hydrometallurgy   HF O 0.71 Refining   C2H2O4 I 1.5 Refining   O2 I 0.93 Refining   HCl O 3 Refining   CO2 O 3.7550
    • 9.2. Maoniuping deposit The calculations are explained in Appendix 5. 9.2.1. Beneficiation The rocks mined in Maoniuping lead to three different outputs: - A mix of aluminium, iron, manganese and lead which is separated at the gravity separation step - A bastnaesite concentrate containing 70% of REEs (Schüler et al. 2011) - Tailings In order to estimate the amount of tailings, it is assumed that the gravity separation recovers only and completely the four elements cited above (Al, Fe, Mn, Pb). Besides, the recovery of REEs during the flotation process is considered of 85% (see Table 5). Figure 21 illustrates the distribution among the three types of outputs. Mn   38.9  kg   12%   Fe   110  kg   33%   Pb   19.7  kg   33.1% 6%   Al   163  kg   Rare   Pb   Mineral recovery 49%   Mn   earths   38.9  kg   19.7  kg  minerals   4%   2%  43.4  kg   4%   Al   163  kg   16%   Rare   Gangue   5.3% 15.8  kg   earth   Fe   minerals   30%   110  kg   36.9  kg   11%   70%   Rare earth concentrate Gangue   625  kg   63%   Rare   earth   minerals   61.6% 6.5  kg   Gangue   1%   609.2  kg   Tailings 99%   Figure 21: Beneficiation process in Maoniuping for one tonne of original rock 51
    • As a consequence, the processing of one tonne of original ore results in the production of: - 331 kg of valuable minerals (Al, Pb, Mn, Fe) - 50 kg of bastnaesite concentrate - 619 kg of tailings Considering the production of REO in 2010 (31,200 t) and assuming a 75% efficiency in the subsequent stages (Schüler et al. 2011), it is estimated that 59,400 t of bastnaesite concentrate were produced that year. The results and assumptions of the beneficiation process are summarised in Table 10.52
    • Table 10: Summary of the beneficiation modelling in Maoniuping Stage   Type   Quantity   Assumptions     o 75% efficiency of the subsequent Beneficiation   Bastnaesite concentrate produced 59,400 tonnes per year stages o 70% recovery of REEs 11.7 tonnes per tonne of rare earth o Full recovery and perfect Beneficiation   Waste rock generated concentrate produced selectivity of Al, Pb, Mn and Fe Table 11: Summary of the mining and comminution processes modelling in Maoniuping Stage   Type   Quantity   Assumptions   o Same stripping ratio as Bayan Obo Mining   Mining rate 7,100 tpd o Beneficiation process assumption (see Table 10) Mining   Energy requirement 21.6 GWh per year o Ditto Mining   Explosives 576 tonnes per year o Ditto Comminution,  Beneficiation  and   o Proportionality to Thor Lake Energy requirement 208 GWh per year Hydrometallurgy   project53
    • 9.2.2. Mining and comminution The mining and comminution are described subsequently to the beneficiation because the data already calculated help determining the requirements. 9.2.2.1. Stripping ratio It is assumed that the stripping ration in Maoniuping is equal to that in Bayan Obo. Thus, the stripping ratio in Maoniuping is considered to be 1.57 (see 9.1.6). 9.2.2.2. Energy requirement for mining operations The energy requirements for the mining operations at Maoniuping were calculated similarly as for Bayan Obo. The stripping ratio assumption makes it possible to calculate the total amount of rock handled and thus the amount of energy required for the mining operations: 21.6 GWh are annually required to power the mining operations. Once again, assuming that the mining operations are carried out with machinery (trucks, shovel…), this amount of energy is provided with fuel. 9.2.2.3. Explosives input Based on the estimation of Nilsson, it is calculated that the annual amount of ANFO used in Maoniuping deposit accounts for 576 tonnes. 9.2.2.4. Comminution Like for Bayan Obo, it is estimated that the comminution, beneficiation and hydrometallurgy operations in Maoniuping require 208 GWh per year. The results and assumptions of the beneficiation process are summarised in Table 11.54
    • 9.2.3. Hydrometallurgy and separation of rare earths In Maoniuping, the process is simplified by the fact that only bastnaesite is processed. Similarly than for Bayan Obo, the flows were estimated from the analysis of the chemical reactions. The stoichiometric numbers of the hydrometallurgy process are summarised in Table 12. ReFCO3 ReFCO3  ReFO + CO23/2 H2SO4 1 CO2 Acidic roasting 2 ReFO + 3 H2SO4 Re2(SO4)3Heat 1 HF + 2 HF +2 H2O 1 H2O Re2(SO4)3 Sulphate Re2(SO4)3+Na2SO42NaRe(SO4)2 ½ Na2SO4 precipitation NaRe(SO4) 2 ½ Na2SO4 Acid leaching 2 NaRe(SO4)2 + 6 HCl  2 ReCl3 3 HCl 3/2 H2SO4 + Na2SO4 + 3 H2SO4 ReCl3 ReCl3 + 3(HX)2  ReX6H3 + 3 HClHeat Solvent extraction 3 (HX)2 ReX6H3 + 3 HCl  ReCl3 + 3(HX)23 (HX)2 9.2.4. Refining The refining process and chemical reactions are the very same as in Bayan Obo (see 9.1.5). The stoichiometric numbers of the refining process are summarised in Table 12. 55
    • Table 12: Summary of the stoichiometric coefficients in Maoniuping Type:  Input/Output   Stoichiometric   Stage   Chemical   (I/O)   coefficients   Hydrometallurgy   H2SO4 I 1.5 Hydrometallurgy   Na2SO4 I 0.5 Hydrometallurgy   HCl I 3 Hydrometallurgy   HF O 1 Hydrometallurgy   CO2 O 1 Hydrometallurgy   H2 O O 1 Hydrometallurgy   H2SO4 O 1.5 Hydrometallurgy   Na2SO4 O 0.5 Refining   C2H2O4 I 1.5 Refining   O2 I 0.93 Refining   HCl O 3 Refining   CO2 O 356
    • 10. Life Cycle inventory Thanks to the estimation of the model and some data in various articles, it ispossible to carry out the Life Cycle Inventory. In this section, every figure is expressedper tonne of REOs produced. Calculations for Bayan Obo (respectively Maoniuping) can be found in Appendix 6(respectively Appendix 7) The composition of one tonne of REOs in Bayan Obo (respectively Maoniuping) isdescribed in Figure 17 (respectively Figure 20). 10.1. Input of chemicals, energy and explosives Table 13 inventories the necessary inputs. 10.2. Air emissions Bayan Obo air emissions are listed in Table 14.10 10.3. Output of wastes and chemicals Table 15 inventories the different wastes rejected when producing a tonne of REOs. 10 For Maoniuping processes, not enough data was found concerning air emissions to proceed to the same description. 57
    • 58 Table 13: Required inputs for the different stages Type  of  input   Stage   Input   Bayan  Obo   Maoniuping   Chemical   Hydrometallurgy H2SO4 677 kg 678 kg Chemical   Hydrometallurgy NH4HCO3 1,091 kg - Chemical   Hydrometallurgy NA2SO4 - 327 kg Chemical   Hydrometallurgy HCl 504 kg 505 kg Chemical   Refining C2H2O4 622 kg 623 kg Chemical   Refining O2 138 kg 111 kg Chemical   Separation P 507 Unknown Unknown Explosive   Mining ANFO 19 kg 18.5 kg Energy   Mining Fuel 710 kWh 692 kWh Energy   Comminution, Beneficiation Electricity 6.83 MWh 6.67 MWh and Hydrometallurgy
    • Table 14: Emission to the air during processes in Bayan Obo Stage   Emission   Quantity   Reference   Milling   Dust 13 kg o Hurst 2010 Milling   Dust containing 1 kg o Schüler, et al. 2011 11 radioactive particles Acidic  roasting   Waste gases (inc. HF, SO2, SO3) 9,600 to 12,000 m3 o Schüler, et al. 2011 Table 15: Outputs discharged Type  of  input   Stage   Output   Bayan  Obo   Maoniuping   Waste   Mining Waste rock 58.2 t 56 t Waste   Beneficiation Waste slag 20.4 t 21.8 t Waste   Beneficiation Radioactive waste slag 1.4 t 300 kg Waste   Amount of ThO2 Beneficiation 14.2 kg 10 kg in waste slag 11 According to Schüler, et al., the Chinese Ministry of Environmental Protections estimates that the amount of thorium containing dust emitted each year is about 61.8 tonnes (0.99 kg per tonne of REO produced with an annual output of 62,400t) (Schüler, et al. 2011).59
    • 60 Type  of  input   Stage   Output   Bayan  Obo   Maoniuping   Waste   Acidic roasting and acid Wastewater 75 m3 12 - leaching Waste   Separation and refining ThO2 in wastewater 0.6 kg 0.26 Chemicals   Hydrometallurgy CO2 423 kg 192 kg Chemicals   Hydrometallurgy H2 O 173 kg 78 kg Chemicals   Hydrometallurgy H2CO3 346 kg - Chemicals   Hydrometallurgy H2SO4 - 640 kg Chemicals   Hydrometallurgy H3PO4 124 kg - Chemicals   Hydrometallurgy (NH4)2SO4 861 kg - Chemicals   Hydrometallurgy NA2SO4 - 327 kg Chemicals   Hydrometallurgy HF 62 kg 87 kg Chemicals   Separation NH4HCO3 61 kg - Chemicals   Separation HCl 28 kg 28 kg Chemicals   Separation H2SO4 38 kg - 12 (Hurst 2010)
    • Type  of  input   Stage   Output   Bayan  Obo   Maoniuping   Chemicals   Separation H2SO4 38 kg - Chemicals   Refining CO2 760 kg 575 kg Chemicals   Refining HCl 476 kg 477 kg Chemicals   Refining C2H2O4 35 kg 35 kg61
    • 11. Life Cycle Impact Assessment In order to conduct this Life Cycle Impact Assessment, different impact categories were defined: - Global Warming - Acidification - Eutrophication - Radioactive waste generation - Land use - Toxicity in wastewater For each of these categories, the LCI results were classified and assigned to one or several category. The calculations of the following sections are all included in Appendix 8. 11.1. Global Warming 11.1.1. Classification The following elements were identified as taking part to global warming: - CO2 emitted during chemical processes - CO2 emitted during production of electricity - CO2 emitted when burning fuel for mining The carbon emissions are quantified in this section. 11.1.2. Characterisation Table 16 summarises the impact indicators concerning global warming. Table 16: Impact indicator for global warming Classification   Unit   Bayan  Obo   Maoniuping   Emissions  from   kg of CO2 1,180 770 chemical  reactions   Emissions  from     kg of CO2 170 170 fuel  burning   Emissions  from   kg of CO2 5,100 5,000 electricity  use   Overall  emissions   kg of CO2 6,450 5,94062
    • 11.2. Acidification 11.2.1. Classification The following elements were identified as taking part to the acidificationphenomenon: - Sulphur Dioxide (SO2) - Hydrochloric acid (HCl) - Hydrofluoric acid (HF) - Ammonia (NH3) 11.2.2. Characterisation Table 17 summarises the impact indicators concerning acidification. Table 17: Impact indicator for acidification Classification   Unit   Bayan  Obo   Maoniuping   SO2  (gas)   kg of SO2 24.8 640 HCl   kg of SO2eq 444 444 HF  (gas)   kg of SO2eq 99 139 NH3   kg of SO2eq 115 - Atmosphere   acidification   kg of SO2eq 124 779 potential   Wastewater   acidification   kg of SO2eq 559 444 potential   63
    • 11.3. Eutrophication 11.3.1. Classification The following elements were identified as taking part to the acidification phenomenon: - Ammonia - Phosphate 11.3.2. Characterisation Table 18 summarises the impact indicators concerning eutrophication. Table 18: Impact indicator for eutrophication Classification   Unit   Bayan  Obo   Maoniuping   Phosphates   kg of H3PO4 124 - Ammonia   kg of H3PO4eq 304 - Discharge  in   428 - kg of H3PO4eq wastewaters   11.4. Radioactive waste generation 11.4.1. Classification The following types of radioactive waste were identified: - Radioactive waste slag - Radioactive wastewater 11.4.2. Characterisation Table 19 summarises the impact indicators concerning radioactive waste generation. Table 19: Impact indicator for radioactive waste generation Classification   Unit   Bayan  Obo   Maoniuping   Activity  of  waste   Bq 5.1 107 3.6 107 slag   Specific  activity  of   Bq/kg 3.6 104 1.25 105 waste  slag   Activity  of   Bq 2.1 106 9.3 105 wastewater   Specific  activity  of   m3 2.9 104 - wastewater  64
    • Classification   Unit   Bayan  Obo   Maoniuping   Radioactivity   Bq 5.3 107 3.7 107 discharge   11.5. Land use 11.5.1. Classification The following elements were identified as taking part to land use: - waste rock - wastewater 11.5.2. Characterisation Table 20 summarises the impact indicators concerning land use. Table 20: Impact indicator for land use Classification   Unit   Bayan  Obo   Maoniuping   Waste  rock   m3 20.4 23.8 Wastewater   m3 75 - Overall  volume   m3 95.4 23.8 required   11.6. Toxic chemical discharge in wastewater In this section, the different sources of toxicity are listed. Their toxicity is describedin Appendix 9. 11.6.1. Classification The following elements were identified as potential toxic elements discharged inwastewaters: - Oxalic acid - Ammonium bicarbonate - Ammonium sulphates - Sodium sulphates - Sulphuric acid 65
    • 11.6.1. Characterisation Table 21 summarises the impact assessments concerning discharge of toxic chemicals in wastewaters. Table 21: Impact indicator for toxicity in wastewater Classification   Unit   Bayan  Obo   Maoniuping   Oxalic  acid   kg 35 35 Ammonium   kg 61 - bicarbonate   Ammonium   kg 861 - sulphates   Sodium  sulphates   kg - 32766
    • 12. Life Cycle Interpretation 12.1. Identification of the significant issues This section aims at identifying the data elements, the assumptions that contributethe most to the results of the LCI and LCIA. It is also focused on determining whetherthere are anomalies in the results or not. 12.1.1. Contribution analysis 12.1.1.1. Model The process modelling is the keystone of this LCA. This modelling helpeddescribed what are the different stages. As a consequence, the results depend directly onthis model, it represents a significant contributor. The chemical reactions were described based on a literature review, they play anessential role in the calculation of results. The beneficiation process was not described in much detail. As a result it is notpossible to estimate the inputs and outputs necessary to its operations. Seven impact categories were defined in the LCIA. As a result, only impacts fromthese categories were discussed. 12.1.1.2. Data Throughout the LCA, the 2010 productions of both Bayan Obo and Maoniupingdeposits have been extensively used. Concerning the data, a significant issue was the very low availability of dataconcerning Maoniuping’s deposit contrary to Bayan Obo’s deposit. 12.1.1.3. Assumption A few assumptions are significant to the results of the LCA: - it is assumed that the daily mining rate is proportional to the REO output of a deposit, as a result it is estimated that the daily mining rate was 16,250 tpd in 2010. This figure is used numerous times throughout the LCA. - for the energy calculations (for the comminution, beneficiation and hydrometallurgy operations), it is assumed that the two Chinese mines can be compared to a Canadian mining project. This represents the most of the energy requirements. - the hydrometallurgy and refining operations are assumed to have a 75% efficiency. Besides, it was assumed that each chemical step had a efficiency of 94.4% - the chemical reactions were assumed to take place with stoichiometric quantities - it is assumed that the chemicals used are neither recovered nor recycled, they all end up in wastewater 67
    • 12.2. Completeness, sensitivity and consistency of data 12.2.1. Completeness check For each mine, the data calculated in the LCI and LCIA are consistent with both the goal and the scope of the LCA. The data cover every primary activity identified in the model of the processes. However, within the primary activities, results are sometimes not complete due to a lack of data. 12.2.1.1. Raw material For this matter, the data are as complete as possible. 12.2.1.2. Energy The following energy requirements were not considered due to a lack of data: - energy consumed during refining operations (e.g. rare earth oxidation) - energy consumed during the transport of the ores As a consequence, it is likely that the energy consumption and the carbon emissions are higher than calculated. 12.2.1.3. Chemical inputs and outputs The following chemical inputs and outputs were not considered due to a lack of data: - chemicals used during the beneficiation process and notably the froth flotation and the associated discharge/recovery - chemicals used for the separation of REEs such as P507 - chemicals used alongside chemical reactions (e.g. solvents, catalysts, pH regulators) As a result, their flows are unknown. 12.2.1.4. Water consumption The water consumption was not estimated for any of the two mines due to a lack of data on this matter. 12.2.1.5. Environmental releases The releases that were described and quantified are only those that were documented in the literature. Therefore, it is likely that other unidentified releases to air or water happen during these operations. 12.2.2. Sensitivity check The sensitivity of the assumptions is described in Table 22. 12.2.3. Consistency check All the assumptions described in section 12.1.1.3 are found to be consistent with the goal and scope of the study. On the contrary, the process modelling described in section 12.1.1.1 is found to be inconsistent with the goal of the study. Leaving the beneficiation process unresolved68
    • makes that the results do not describe correctly the necessary flows to achieve REOs. Dueto this inconsistency, it is likely that several different chemical inputs and outputs areneglected as well as some environmental releases. 12.2.4. Limitations of the study In this section, the level of confidence in the assumptions is discussed as well astheir sensitivity. Table 22: Assumptions analysis Level  of  confidence   Assumptions   Implications  and  sensitivity   (low/medium/high)13   The results are proportional to the mining Mining  rate   medium rate. So it is not likely that the results will assumption   change drastically because of this assumption. This assumption neglects any economy ofProportionality   scales which is likely to be the case in reality. to  Thor  Lake   low A significant change in this assumption is project   likely to change considerably the global warming impact assessment. 75%  efficiency   This data is based on the literature and is of  the   therefore reliable. If it were to change, ithydrometallurgy   high would cause the chemical inputs and outputs and  refining   to change inverse proportionally. processes  Recovery  rate  of   the   This data is based on the literature. It is a beneficiation   high sensitive data because it helped to calculateprocess  in  both   wastes, radioactive wastes as well as land use. mines   Full  recovery   and  perfect   This assumption is not very sensitive since aselectivity  of  Fe   low difference would slightly change the amountand  Nb  minerals   of waste rock produced. in  Bayan  Obo   Full  recovery   and  perfect   This assumption is not very sensitive since aselectivity  of  Al,   low difference would slightly change the amount Pb,  Mn  and  Fe   of waste rock produced. in  Maoniuping   13 These are personal assessments. 69
    • Level  of  confidence   Assumptions   Implications  and  sensitivity   (low/medium/high)13   Same   stripping   This assumption is sensitive since a slight ratio  in   low change is likely to lead to significant Maoniuping   differences in many categories as  Bayan   Obo   12.3. Conclusions of the life cycle assessment This life cycle assessment was carried out in order to provide information about the production of REOs and estimate the energy and material flows necessary to it. The conclusion of this study is divided into two sections: analysis where the results are discussed and opinion where the study in itself is discussed. 12.3.1. Analysis 12.3.1.1. Global warming For both deposits, the CO2 emissions related to the production of a tonne of REO are about 6 tonnes. This is a considerable ratio, that has to be taken into account when studying products that contains REEs. Finally, the emission of both Maoniuping and Bayan Obo operations in terms of CO2 appear to be quite similar. 12.3.1.2. Acidification potential The acidification potential (when producing a tonne of REOs) appears to be significant since hundreds of kilograms of SO2eq are released both in the atmosphere and wastewater. Besides, the operations in Maoniuping and Bayan Obo seem to have a comparable acidification potential. 12.3.1.3. Eutrophication potential The eutrophication potential of Maoniuping is nil. This is due to the absence of monazite in Maoniuping’s ore. On the contrary, the operations in Bayan Obo generate a significant amount of phosphate (or phosphate equivalent) since over 400 kg of phosphate equivalent are generated when producing a tonne of REOs. 12.3.1.4. Radioactive waste generation Both operations generate significant radioactivity. Although this radioactivity is already occurring in the virgin ore, the result of these processes is to concentrate radioactive materials. Therefore, the radioactive wastes have a higher radioactivity than natural ore. According to the UK regulation, they can be classified as low level radioactive waste70
    • (European Commission 1998). Thus, they need to be disposed of carefully in order toavoid spilling this radioactive concentrate out. Although the wastewaters appear to be less radioactive than the waste slag, it isnecessary to build secure impoundment, to prevent radioactive material from percolatinginto the soil and polluting ground waters. 12.3.1.5. Land use Although the volume of waste generated per tonne of REO does not seem tooimportant, the accumulation of all these wastes through decades of functioning havecreated massive stockpiles of waste. As an example, some figures are given below concerning Bayan Obo deposit: - surface of the tailing impoundment: 11 km2 (roughly 65 million m3) (Schüler et al. 2011) - surface of the open pit mines (including all orebodies): 8.13 km2 (Wu 2010) - surface of the waste rock storages: 5.6 km2 (estimated from an aerial picture of Bayan Obo deposit) 12.3.1.6. Discharge of toxic chemicals Discharge of toxic chemicals is a serious issue in both Maoniuping and Bayan Obo.Much chemicals end up in wastewater and disposing toxic chemical in a pond may resultin toxicity infiltrating into soils or evaporating in the air. Both deposits reject oxalic acid which appears to be potentially the most toxicchemical discharged in the ones that were identified in this study. A newspaper report by Simon Parry describing the effects of the “lake of toxicwaste” is quoted in Appendix 10. 12.3.2. Discussions on the life cycle assessment 12.3.2.1. Scope definition The scope was defined in concordance with two ideas: - the assessment of the environmental impacts of the production of REOs represents a comprehensive purpose as this is the first step in the production of every REE of any form - the scope took into consideration the time available for this study Consequently, although the study could have encompassed the production of rareearth metals or even rare earth products, it is estimated that the scope was the bestcompromise possible. 12.3.2.2. Assumptions Several assumptions were made throughout this LCA. Although most of them arebased on literature, some assumptions were identified as critical as they are sensitive anddo not have a high level of confidence: - the assumption on the stripping ratio in Maoniuping was made in order to enable further calculations. It has a low level of confidence and a high sensitivity 71
    • - the proportionality to the Thor Lake project neglects any economy of scale. This assumption appears to be critical in the calculation of the global warming impacts although it does not have a high level of confidence. 12.3.2.3. Process modelling The results of both Maoniuping and Bayan Obo are really close. This can be explained with two reasons: - the model for Maoniuping lacked several data and therefore numerous assumption were based on Bayan Obo information - the two deposit are very similar in terms of ore and rare earth content and composition The process modelling is likely to be a faulty part of this LCA. It was chosen taking into account the availability of information and data. Thus they result more from an obligation than a choice. Besides, the process modelling is the keystone of the whole LCA. Therefore, if this study is to be improved, it would be interesting to: - describe the beneficiation operations in more details - model or find information on the consumption of water throughout the production of REOs - find more precise information on Maoniuping’s operations - describe more meticulously the chemical steps, chemical reactants and conditions 12.3.2.4. Life cycle inventory In the life cycle inventory, attention was paid to chemical inputs and outputs, air emissions and waste generation. These categories were selected based on the available information. However, it would have been interesting to also focus on the water consumption since it is likely to be a significant in beneficiation and hydrometallurgy processes. Besides, the operation in Bayan Obo takes place in an arid environment. Therefore, the impacts of abstracting water can be important. 12.3.2.5. Life cycle impact assessment Only six categories were chosen for the LCIA since it takes into account the description carried out in the life cycle inventory. However, if it had been possible, this LCIA could also have focuses on other midpoint impacts: - soil toxicity (modelling of the infiltrations) - stream toxicity (modelling of the infiltrations) - water use (water consumption modelling) Further studies could get down to assessing these impacts. 12.3.2.6. Acquisition of information The LCA of this study relies only on information found in literature and assumptions. It would be certainly useful to have a look at other kinds of information such as LCA software database, governmental or industrial documentations. Since the latter is almost exclusively in Chinese, it would be to through it with a native Chinese speaker in order to collect other primary data.72
    • 12.3.2.7. Specificity of the life cycle assessment This study was focused on two Chinese mines that were described in details.However, general assumptions were made, and only very generic processes werescrutinised. As a result, it is likely that the results can be generalised to some extent to other rareearth projects both in China and abroad. 73
    • 13. Conclusion The aim of this study was to assess some of the environmental impact of producing rare earth oxides. More specifically, attention was given to two Chinese mines which account for 70% of the global rare earth production. Thus, after a description of the operations in these both mines, it was decided to carry out a life cycle assessment methodology to these mines in order to evaluate the environmental impacts related to the following categories: global warming, acidification, eutrophication, radioactive waste generation, land use and toxicity in waste waters. This life cycle assessment was composed of several phases: firstly the processes taking place in the two mines were described in details. Secondly, a life cycle inventory listed every input and output flows necessary to the operations. Thirdly, the impacts related to the above categories were assessed and expressed in a same unit. Finally, the life cycle interpretation helped to analysed the results. It appeared that the production of rare earth oxides in these two mines is associated with a high environmental cost. In addition to CO2 emissions, the processes generates massive amount of waste slag (some of which is radioactive) and wastewater that have to be dealt with properly. The waste management has to be strict in order to avoid radioactive or toxic run-offs. As a result, it emerged that the low economical cost of Chinese rare earth production goes along a significant environmental cost that should definitely be taken into consideration when producing and consuming rare earth elements. The introduction of quotas in Chines exportation is possibly a political sign that Chinese authorities do not want to bear alone the responsibility of supplying the world with rare earth elements and try to share that environmental burden with other countries.74
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    • Appendix Appendix 1: USGS and Chinese classification1. Different classifications a. USGS USGS defines the reserve as “the part of the reserve base which could beeconomically extracted or produced at the time of determination”. The reserve base being“the part of an identified resource that meets specified minimum physical and chemicalcriteria related to current mining and production practices […] The reserve base includesthose resources that are currently economic (reserves), marginally economic (marginalreserves) and some of those that are currently subeconomic (subeconomic resources)”(USGS 2011). b. Chinese classification According to Tse, “the Chinese reserve classification system best approximatesreserves as defined in the U.S. Bureau of Mines and U.S. Geological Survey (1980) inUSGS Circular 831”(Tse 2011). In this document, reserves are defined as “that portion ofan identified resource from which a usable mineral or energy commodity can beeconomically and legally extracted a the time of determination” (USGS 1980). 81
    • Appendix 2: Description of the flotation processes The flotation process consists in mixing the ore with chemicals to make the bastnaesite/monazite hydrophobic. Then air is injected through the agitated slurry (mix of ore and water) to produce froth. Since the rare earth ores is hydrophobic, it is attracted to air bubbles and thus stays at the surface of the mixture. Waste material sinks to the bottom of the container and can be removed (EPA 1994). There are six broad types of flotation reagents (Fuerstenau et al. 2007): - the frother is added to control bubble size and froth stability - the collectors are surface-active reagents that impart hydrophobicity to minerals - the activators enhance collector adsorption onto a specific mineral - depressants are reagents that prevent collector adsorption to unwanted mineral surfaces - modifiers modify the flotation environment - flocculants are added to assist dewatering of the flotation concentrates82
    • Appendix 3: Description of the solvent extraction process The solvent extraction of REEs in EHEHPA follows a mere observation: the biggerthe atomic number of the REE the more stable the resulting complex. Figure 22 shows how the separation factor between two REEs matches with thatprinciple (Hao et al. 1995). Figure 22: Separation factor of rare earths in the Ln(III)-HCl-EHEHPA system (Sato 1989) As a result, the process to separate REEs from each other uses that principle. It iscomposed of several steps as described in Figure 23. Figure 23: Separation flowsheet for bastnasite (Yan et al. 2006) The machine used for the solvent extraction is a mixer settler extractor (Zhong et al.2010) (Zhong 1995). 83
    • Appendix 4: Calculations for the Bayan Obo processes modelling 2. Mining a. Mining rate Chinese production of REOs increased by 8.3% between 2006 and 2010 (from 120,000 to 130,000) (USGS 2006 ; USGS 2011), it is assumed that Bayan Obo’s production increased similarly. As a result, the mining rate in 2010 is 8.3% bigger than the one in 2006: 15,000 ∗ 1.083 ≈ 16,200  !"# b. Energy requirement Calculation of the annual energy consumption for the mining operations: - daily energy consumption: 16,200 ∗ 7.5  !"ℎ = 121.5  !"ℎ - annual energy consumption: 121.5 ∗ 365 ≈ 44.3  !"ℎ c. Explosives input Calculation of the annual amount of ANFO required: - daily requirements: 16,200 ∗ 0.2  !" = 3,240  !" - annual requirements: 365 ∗ 3.24 ≈ 1,180  !"##$% 3. Comminution Considering that the power requirements of Bayan Obo are proportionally equal to those estimated for the Thor Lake project, the average power was estimated: - average power requirement: 16,200 6∗ = 48.6  !" 2,000 - annual amount of energy: 48.6 ∗ 8,760 ≈ 426  !"ℎ 4. Beneficiation Calculation of the results displayed in Table 8: - since the annual output is 62,400 t and considering that the concentrate contains 60% of REEs and that the subsequent steps have an overall efficiency of 75%. The amount of rare earth concentrate produced is: 62,400 ≈ 139,000  !"##$% 0.75 ∗ 0.6 - the amount of waste rock generated per tonne of rare earth concentrate is calculated taking into account that 589 kg of waste rock are generated when producing 60 kg of rare earth concentrate. As a result, the amount of waste rock produced per tonne of rare earth concentrate is: 589 ∗ 1! = 9.8  !  !"  !"#$%  !"#$ 60 5. Hydrometallurgy and refining The stoichiometric quantities were calculated directly from the models exposed in sections 9.1.4 and 9.1.5.84
    • 6. Stoichiometry The stoichiometric coefficients are calculated directly from the chemical reactions,however, the stoichiometric coefficient for O2 in the refining process needs to beexplained. This calculation is based on the relative proportion of light REEs at this stage. Thisproportion is illustrated in Figure 24: Pr   5%   Sm   Nd   2%   18%   La   24%   Ce   51%  Figure 24: Relative proportion of light rare earth elements in Bayan Obo concentrate (Spooner 2005) As a result, knowing that the stoichiometric coefficient for La, Nd and Sm is 0.75, 1for Ce and 1.8 for Pr, it is possible to calculate the overage coefficient: 0.24 + 0.18 + 0.02 ∗ 0.75 + 0.51 ∗ 1 + 0.05 ∗ 1.8 = 0.93 85
    • Appendix 5: Calculations for the Maoniuping processes modelling 1. Beneficiation Calculation of the results displayed in Table 10: - since the annual output is 31,200 t and considering that the concentrate contains 70% of REEs and that the subsequent steps have an overall efficiency of 75%. The amount of bastnaesite concentrate produced is 31,200 ≈ 59,400  !"##$% 0.75 ∗ 0.7 -the amount of waste rock generated per tonne of rare earth concentrate is calculated taking into account that 619 kg of waste rock are generated when producing 52.7 kg of bastnaesite concentrate. As a result, the amount of waste rock produced per tonne of rare earth concentrate is: 619 ∗ 1! = 11.7  !  !!  !"#$%  !"#$ 52.7 2. Mining and comminution a. Mining rate calculation Since bastnaesite concentrate represents 5.3% of all the rock processed in beneficiation, it is possible to calculate the amount of rock processed in the beneficiation from the amount of bastnaesite concentrate produced: 59,400 = 1.12  10!  !"##$% 0.053 The stripping ratio being 1.57, it is possible to calculate the annual amount of rock excavated in the mining operations: 1.12  10! ∗ 1 + 1.57 = 2.88  10!  !"##$% As a result, the mining rate is: 2.88  10! = 7,900  !"# 365 b. Energy requirements for mining - Annual energy requirements: 2.88  10! ∗ 7.5  !"ℎ = 21.6  !"ℎ c. Explosives Thanks to the annual amount of rock handled and Nilsson’s figure it is possible to calculate the annual amount of explosive required: 2.88  10! ∗ 0.2 = 576  10!  !" = 576  ! 3. Comminution Considering that the power requirements of Maoniuping are proportionally equal to those estimated for the Thor Lake project, the average power was estimated: - average power requirement: 7,900 6∗ = 23.7  !" 2,000 - annual amount of energy: 23.7 ∗ 8,760  ℎ!"#$ ≈ 208  !"ℎ86
    • - Stoichiometry The stoichiometric coefficients are calculated directly from the chemical reactions,however, the stoichiometric coefficient for O2 in the refining process needs to beexplained. This calculation is based on the relative proportion of light REEs at this stage. Thisproportion is illustrated in Figure 25. La   30%   Pr   5%   Nd   13%   Ce   51%   Sm   1%   Figure 25: Relative proportion of light rare earth elements in Maoniuping concentrate As a result, knowing that the stoichiometric coefficient for La, Nd and Sm is 0.75, 1for Ce and 1.8 for Pr, it is possible to calculate the overage coefficient: 0.3 + 0.13 + 0.01 ∗ 0.75 + 0.51 ∗ 1 + 0.05 ∗ 1.8 = 0.93 87
    • Appendix 6: Calculation of the life cycle inventory data for Bayan Obo 1. Molar quantity Firstly, the molar quantity contained in one tonne of REOs is calculated. Considering that one tonne of REOs is composed as in Figure 17. It is calculated that it contains 4,346 moles of the different REOs. 2. Input of consumed product a. Chemicals Thanks to the above molar quantity and the stoichiometric coefficients modelled in section 9.1. It is possible to calculate the stoichiometric amount for each chemical input, these results are given in Table 23. Table 23: Calculation of the chemical inputs for Bayan Obo Minimum   Required  mass   Stoichiometric   Molar  mass   required  mass   (94.4%   Chemical   coefficient   (g/mol)   (stoichiometric   efficiency)   quantities)   H2SO4   1.5 98 639 kg 677 kg NH4HCO3   3 79 1,030 kg 1,091 kg HCl   3 36.5 476 kg 504 kg C2H2O4   1.5 90 587 kg 622 kg O2   0.93 32 104 kg 111 kg b. Explosives To calculate the amount of explosive used per tonne of REOs, the annual amount of ANFO used (1,180 t) is merely divided by the annual oxide output of Bayan Obo (62,400t). c. Energy The energy requirements for the production of a tonne of REOs are calculated similarly than for the explosives: with a simple division of the energy inputs described in section 9.1. 3. Output of wastes and chemicals a. Wastes From section 9.1.6, the annual amount of waste rock generated in Bayan Obo can be calculated:  2.31  10! ∗ 1.57 = 3.63  10!  !"##$% As a result, per tonne of REOs produced, the amount of waste rock generated is 3.63  10! ∗ = 58.2  !"##$% 62,40088
    • b. Waste slag The waste slag is the rock discharged after the beneficiation process. The amount ofrock discharged at this stage is: 2.31  10! ∗ 0.589 = 1.36  10!  !"##$% Hence, the amount of waste slag generated per tonne of REO produced is 21.8tonnes. Among this waste slag it is possible to distinct between radioactive and non-radioactive waste slag. The radioactive waste slag amounts to 1.4 tonnes (Xu and Peng 2009). As a result,the non radioactive waste slag amounts to 20.4 tonnes. c. Thorium oxide in wastewater and waste slag According to Chen, the thorium oxide content in Bayan Obo ore is 0.04%. As aresult, the amount of ThO2 processed each year in the comminution and beneficiationsteps is equal to (Chen et al. 2003): 2.3  10! ∗ 0.04% = 925  !"##$% According to Figure 20, 95.9% of the processed thorium oxide ends up in waste slagand 4.1% ends up in rare earth concentrate. As a result, the annual amount of ThO2 thatends up in waste slag is equal to: 925 ∗ 0.959 = 887  !"##$% Consequently, the amount of thorium oxide that ends up in waste slag per tonne ofREOs produced is equal to: 887 = 14.2  !" 62,400 Similarly, it is calculated that the amount of ThO2 that ends up in wastewater foreach tonne of REO is equal to 0.6 kg. d. Chemicals H2SO4, NH4HCO3, HCl and C2H2O4 outputs result from the fact that each reactionwas considered to have a 94.4% efficiency. Therefore, even if all the rare earth moleculesare processed, some of these chemicals remain in the solution and are discharged inwastewater. What remains in solution is the amount of chemical that is in excess so thatall the rare earth molecules are transformed. The other chemical outputs are calculated similarly than for the chemical inputs (seeTable 23). Table 24: Calculation of the chemical outputs for Bayan Obo Stoichiometric   Stoichiometric   Chemical   Molar  mass  (g/mol)   coefficient   output   CO2   2.21 44 423 kg H2O   2.21 18 173 kg H2CO3   1.5 53 346 kg 89
    • Stoichiometric   Stoichiometric   Chemical   Molar  mass  (g/mol)   coefficient   output   H3PO4   0.29 98 124 kg (NH4)2SO4   1.5 132 861 kg HF   0.71 20 62 kg CO2   3 44 574 kg HCl   3 36.5 476 kg90
    • Appendix 7: Calculation of the life cycle inventory data for Maoniuping 1. Molar quantity Firstly, the molar quantity contained in one tonne of REOs is calculated. Considering that one tonne of REOs is composed as in Figure 18. It is calculated that it contains 4,353 moles of the different REOs. 2. Input of consumed product a. Chemicals Thanks to the above molar quantity and the stoichiometric coefficients modelled in section 9.2. It is possible to calculate the stoichiometric amount for each chemical input, these results are given in Table 25. Table 25: Calculation of the chemical inputs for Maoniuping Minimum   Required  mass   Stoichiometric   Molar  mass   required  mass   (94.4%  Chemical   coefficient   (g/mol)   (stoichiometric   efficiency)   quantities)   H2SO4   1.5 98 640 kg 678 kg Na2SO4   0.5 142 309 kg 327 kg HCl   3 36.5 477 kg 505 kg C2H2O4   1.5 90 587 kg 623 kg O2   0.93 32 104 kg 111 kg b. Explosives To calculate the amount of explosive used per tonne of REOs, the annual amount of ANFO used (576 t) is merely divided by the annual oxide output of Maoniuping (31,200t). c. Energy The energy requirements for the production of a tonne of REOs are calculated similarly than for the explosives: with a simple division of the energy inputs described in section 9.2. 3. Output of wastes and chemicals a. Wastes From section 9.2, the annual amount of waste rock generated in Bayan Obo can be calculated. The annual amount of rock handled is 365 ∗ 7,900  !"# = 2.88  10! !"##$% (see Appendix 5 for the mining rate calculation). The annual amount of bastnaesite concentrate is 59,400 tonnes (see 9.2.1). 91
    • Since the mining ratio is 1.57, the amount of waste rock generated is: 1.57 2.88  10! ∗ = 1.76  10! !"##$% 1.57 + 1 As a result, per tonne of REOs produced, the amount of waste rock generated is: 1.76  10! = 56  !"##$% 31,200 b. Waste slag The waste slag is the rock discharged after the beneficiation process. The amount of rock discharged at this stage is: 1.12  10! ∗ 0.616 = 6.91  10!  !"##$% (1.12 106 tonnes being the amount of rock processed). Hence, the amount of waste slag generated per tonne of REO produced is 22.1 tonnes. Among this waste slag it is possible to distinct between radioactive and non- radioactive waste slag. The radioactive waste slag amounts to 300 kg (Xu and Peng 2009). As a result, the non radioactive waste slag amounts to 21.8 tonnes. c. Thorium oxide in wastewater and waste slag According to Xu and Peng, the amount of thorium oxide that ends up in waste slag per tonne of REOs produced is 10 kg (Xu and Peng 2009). From Figure 21, it is calculated that 97.5% of the ThO2 goes into waste slag and 2.5% into rare earth concentrate (and then in wastewater). As a result, the amount of ThO2 in wastewater is estimated to be 0.26 kg per tonne of REOs produced. d. Chemicals H2SO4 and C2H2O4 outputs result from the fact that each reaction was considered to have a 94.4% efficiency. Therefore, even if all the rare earth molecules are processed, some of these chemicals remain in the solution and are discharged in wastewater. What remains in solution is the amount of chemical that is in excess so that all the rare earth molecules are transformed. The other chemical outputs are calculated similarly than for the chemical inputs (see Table 23). Table 26: Calculation of the chemical outputs for Maoniuping Stoichiometric   Stoichiometric   Chemical   Molar  mass  (g/mol)   coefficient   output   CO2   1 44 192 kg H2O   1 18 78 kg H2SO4   1.5 98 640 kg Na2SO4   0.5 142 327 kg HF   1 20 87 kg92
    • Stoichiometric   Stoichiometric  Chemical   Molar  mass  (g/mol)   coefficient   output   CO2   3 44 575 kg HCl   3 36.5 505 kg 93
    • Appendix 8: Calculation of the life cycle impact assessment data 1. Global warming a. Emissions from chemical reactions These data come directly from the life cycle inventory in section 10. b. Emissions from fuel burning in the mining operations Firstly, the amount of energy necessary for the mining phase is into a volume of gasoline. This is done based on gasoline energy density (35 MJ/L) (Tribal Energy and Environmental Information 2011). Then, the emission of CO2 is calculated considering that the combustion of gasoline generates 2.38 kg CO2 per litre (EPA 2005). Results are displayed in Table 27. Table 27: CO2 emissions for mining operations   Baotou   Maoniuping   Mining  energy  (kWh)   710 kWh 692 kWh Equivalent  amount  of   73 71 gasoline  (L)   Emissions  of  CO2  (kg)   174 169 c. Emissions from electricity use Assuming that the processes of comminution, beneficiation and hydrometallurgy are completely powered with Chinese electricity, it is possible to calculate the amount of CO2 generated during theses stages. In average, the Chinese electricity produces 745 g of CO2 per kWh (International Energy Agency 2010). Results are displayed in Table 28. Table 28: CO2 emissions from electricity use   Baotou   Maoniuping   Required  energy  (MWh)   6.83 6.67 Emissions  of  CO2  (tonne)   5.1 5.0 2. Acidification a. SO2 calculation The sulphur dioxide is produced during the acidic roasting where the following reaction takes place: 2 H2SO4  2 SO2 + 2 H2O + O294
    • Assuming that all the sulphuric acid that is not consumed during the acidic roastingproduces sulphur dioxide, it is possible to estimate the quantity of SO2 is rejected. Thecalculations are exposed in Table 29. Table 29: Calculation of the SO2 emissions   Baotou   Maoniuping   Excess  of  H2SO4  (kg)   38 640 Quantity  of  moles   388 6531 SO2  emitted  (kg)   25 418 b. Characterisation factor In order to express both HCl, HF and NH3 in a same unit, the characterisation factordeveloped by Azapagic was used (Azapagic 2011). It helped to convert these chemicalsinto SO2eq. The characterisation factors are described in Table 30. Table 30: Acidification potential characterisation factors (Azapagic 2011) Chemical Acidification Potential (vs. SO2) SO2 (sulphur dioxide) 1 HCl (hydrogen chloride) 0.88 HF (hydrogen fluoride) 1.6 NH3 (ammonia) 1.88 Thus, it is possible to express the data calculated in the LCI into SO2eq regardingtheir acidification potential. The results are exposed in Table 31. Table 31: Acidification potential of different chemicals   Baotou   Maoniuping   HCl  discharge  (kg)   504 505HCl  acidification  potential   444 444 (kgSO2eq)   HF  discharge  (kg)   62 87 HF  acidification  potential   99 139 (kgSO2eq)   NH3/NH4+  discharge  (kg)   61 - 95
    •   Baotou   Maoniuping   NH3  acidification  potential   115 - (kgSO2eq)   3. Eutrophication a. Characterisation factor In order to express ammonia and phosphate in a same unit, the characterisation factor developed by Azapagic was used (Azapagic 2011). It helped to convert these chemicals into H3PO4eq. The characterisation factors are described in Table 32. Table 32: Eutrophication potential characterisation factors (Azapagic 2011) Chemical Acidification Potential (vs. SO2) Phosphate 1 Ammonia 0.33 Nitrates 0.42 Thus, it is possible to express the data calculated in the LCI into H3PO4eq regarding their eutrophication potential. The results are exposed in Table 33. Table 33: Eutrophication potential of different chemicals   Baotou   Maoniuping   Phosphate  discharge  (kg)   124 - Phosphate  eutrophication   124 - potential  (kgH3PO4eq)   Ammonia  discharge  (kg)   922 - Ammonia  eutrophication   304 - potential  (kgH3PO4eq   4. Radioactive waste generation a. Radioactive waste slag The radioactivity is calculated from the following formula: !"  (2) !"#$%"&$($) = !!"#$% ∗ !! ! where: - Natoms is the number of radioactive atoms - t1/2 is the half life (14.05 billion years for ThO2)96
    • Calculations are exposed in Table 34. Table 34: Activity in waste slag   Baotou   Maoniuping   Radioactive  waste  slag   1.4 t 300 kg discharge  Amount  of  ThO2  in  waste   14.2 kg 10 kg slag  (kg)   Activity  (Bq)   5.1 107 3.6 107 Specific  activity  (Bq/kg)   3.6 104 1.25 105 b. Radioactive in wastewater Similarly as for the previous section, the quantity of thorium in wastewater wasestimated. The calculations are displayed in Table 35. Table 35: Activity in wastewater   Baotou   Maoniuping   Amount  of  ThO2  in   0.6 0.26 wastewater  (kg)   Activity  (Bq)   2.1 106 9.3 105 Specific  activity  (Bq/m3)   2.9 104 -5. Land use The data are given in Table 15. 97
    • Appendix 9: Toxic chemicals in wastewater 1. Oxalic acid According to Cindy Hurst in a report for the Institute for the Analysis of Global Security (Hurst 2010): “Oxalic acid is poisonous and potentially fatal if swallowed. It is also corrosive and causes severe irritation and burns to the skin, eyes, and respiratory tract, is harmful if inhaled or absorbed through the skin, and can cause kidney damage.” 2. Ammonium bicarbonates In the same report, Hurst writes that (Hurst 2010): “The potential health hazards of ammonium bicarbonate include: Irritation to the respiratory tract if inhaled, irritation to the gastrointestinal tract if ingested, redness and pain if it comes in contact with the eyes, and redness, itching, and pain if it comes in contact with the skin.” 3. Ammonium sulphates The company DSM reports that (DSM 2010): “Ammonium sulphate has a low hazard profile. […] Ammonium sulphate has been tested for several toxicological endpoints (for example, acute toxicity, irritation, repeated dose toxicity). Based on experimental data for analogue substances, no additional adverse health effects are anticipated for the ammonium sulphate. […] Ammonium sulphate has a low bioaccumulating potential. It has been tested for ecotoxicity. Based on these tests there is no need to classify this substance.” 4. Sodium sulphates According to the International Programme on Chemical Safety of the World Health Organisation (International Programme on Chemical Safety 2000): “The Committee considered that the results of the published studies in experimental animals do not raise concern about the toxicity of sodium sulfate. The compound has a laxative action, which is the basis for its clinical use. The minor adverse effects reported after use of ingested purgative preparations containing sodium sulfate may not be due to the sodium sulfate itself.”98
    • Appendix 10: Report on the lake of toxic waste in Baotou (Parry 2011) “When we finally break through the cordon and climb sand dunes to reach its brim,an apocalyptic sight greets us: a giant, secret toxic dump, made bigger by every windturbine we build. The lake instantly assaults your senses. Stand on the black crust for just secondsand your eyes water and a powerful, acrid stench fills your lungs. For hours after our visit, my stomach lurched and my head throbbed. We were therefor only one hour, but those who live in Mr Yan’s village of Dalahai, and other villagesaround, breathe in the same poison every day. Retired farmer Su Bairen, 69, who led us to the lake, says it was initially a novelty –a multi-coloured pond set in farmland as early rare earth factories run by the state-ownedBaogang group of companies began work in the Sixties. ‘At first it was just a hole in the ground,’ he says. ‘When it dried in the winter andsummer, it turned into a black crust and children would play on it. Then one or two ofthem fell through and drowned in the sludge below. Since then, children have stayedaway.’ As more factories sprang up, the banks grew higher, the lake grew larger and thestench and fumes grew more overwhelming. ‘It turned into a mountain that towered over us,’ says Mr Su. ‘Anything we plantedjust withered, then our animals started to sicken and die.’ People too began to suffer. Dalahai villagers say their teeth began to fall out, theirhair turned white at unusually young ages, and they suffered from severe skin andrespiratory diseases. Children were born with soft bones and cancer rates rocketed. Official studies carried out five years ago in Dalahai village confirmed there wereunusually high rates of cancer along with high rates of osteoporosis and skin andrespiratory diseases. The lake’s radiation levels are ten times higher than in thesurrounding countryside, the studies found. Since then, maybe because of pressure from the companies operating around thelake, which pump out waste 24 hours a day, the results of ongoing radiation and toxicitytests carried out on the lake have been kept secret and officials have refused to publiclyacknowledge health risks to nearby villages.” 99