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Residual Mineral Deposits

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Residual mineral deposits; Laterites; Laterite Profile; Laterisation system; Laterite/Bauxite Conditions; Laterite-type Bauxite, Constitution of Bauxite, Types of deposits; Origin and Mode of formation; Clay (Kaolinite) Deposits; Nickel Laterite Deposits; Mineralogy and Types of lateritic nickel ore deposits; World Nickel Laterite Deposits; Processing of Ni Laterites; Example: Ni-laterites, Ni in soils in east Albania

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Residual Mineral Deposits

  1. 1. Topic 8: Residual (eluvial or laterite) Mineral Deposits Hassan Z. Harraz hharraz2006@yahoo.com 2012- 2013 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 1
  2. 2. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 2 Outline of Topic 8: We will explore all of the above in Topic 8  RESIDUAL CONCENTRATION  Definition of Residual mineral deposits  Definition of Laterites  Laterite/Bauxite Conditions  Laterite Profile  Laterisation system 1) Laterite-type Bauxite  Characteristics  Constitution of Bauxite  Types of deposits  Origin and Mode of formation  World bauxite reserves 2010  Clay (Kaolinite) Deposits  Source Materials  Mode of Formation 2) Nickel Laterite Deposits  Definition  Mineralogy and Types of lateritic nickel ore deposits  World Nickel Laterite Deposits  Processing of Ni Laterites  Example: Ni-laterites, Ni in soils in east Albania
  3. 3. RESIDUAL CONCENTRATION:  Result in the accumulation of valuable minerals when undesired constituents of rocks or mineral deposits are removed during weathering.  The concentration is due largely to a decrease in volume effected almost entirely by surficial chemical weathering.  The residues may continue to accumulate until their purity and volume make them of commercial importance. Process of Formation The requirement for residual concentration of economic mineral deposits: 1) The presence of rocks or lodes containing valuable minerals, of which the undesired, substances are soluble and desired substances are generally insoluble under surface conditions. 2) The climatic conditions must favour chemical decay. 3) The relief must not be too great, or the valuable residue will be washed away as rapidly as formed. 4) Long-continued crustal stability is essential in order that residues may accumulate in quantity and the deposits may not be destroyed by erosion. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 3 The concentration of ore deposits by weathering processes occurs as soluble rock, such as limestone, is removed in solution, leaving insoluble minerals concentrated as a residue.
  4. 4. Definition of Residual mineral deposits  Residual mineral deposits formed and concentrated by chemical weathering reactions at the earth’s surface. During chemical weathering and original body of rock is greatly reduced in volume by the process of leaching, which removes ions from the original rock. Elements that are not leached form the rock thus occur in higher concentration in the residual rock.  leaching of rock leaves residual materials behind (i.e., Form by the removal of soluble minerals (leaching)  Insoluble minerals (residues) get concentrated at the weathering site  These deposits often form as a result of intense chemical weathering in warm tropical climates that receive high temperatures and high amounts of rainfall which produces highly leached soils rich in both iron and aluminium.  Resource from residual mineral deposits: Al (Bauxite), Ni (Nickeliferous-laterite), Fe and kaolinite. The most important ore of Aluminum, bauxite, forms in tropical climates where high temperatures and high water throughput during chemical weathering produces highly leached lateritic soils rich in both iron and aluminum. Most bauxite deposits are relatively young because they form near the surface of the Earth and are easily removed by erosion acting over long periods of time.  In addition, an existing mineral deposit can be turned in to a more highly concentrated mineral deposit by weathering in a process called secondary enrichment. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 4
  5. 5.  Laterite - the resulting soil layer, typically red in color due to the presence of iron oxides and hydroxides.  Nodular, red to yellow or brown hematite and goethite with as much as 20% Al2O3.  Laterites are formed mostly in the sub-tropical and tropical regions between 25° North and 25° South latitude.  Laterites also occur in temperate zones, but were formed when those regions were tropical millions of years ago.  Laterite deposits can be thick, up to 20 m.  It is precipitated into laterite with concentrations ~1-3% by weight.  Laterites deposits of aluminum, iron, nickel, cobalt, chromium, titanium, copper are also formed.  In the case of a nickel laterite, nickel would be 0.25% by weight in peridotite: 6 – 20 m thick on top of mafic and ultramafic rocks.  Examples: Guinea, Guyana, Indonesia, Australian, Jamaica, Cuba and the Philippines.  Laterites are source of metals:  Ni, Co, Cr, Fe (from laterites derived from ultramafic rocks)  Al (from laterites derived from aluminous rocks) Definition of Laterites 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 5 Schematic soil profile in a laterite showing the progression of weathering effects on rock. Some commodities, such as aluminum and nickel, are enriched by weathering. Modified slightly from Elias (2002).
  6. 6. Laterite/Bauxite Conditions 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 6  Climate  Parent Rock Composition  Subtle Eh-pH Controls  [1],[2]: Al and Fe leached  [3],[4]: low solubility so need Fe, Al rich parent material  [5]: enough Fe mobility to form Fe-laterites  [6]: optimal for bauxites 1 2 3 4 5 6
  7. 7. Example: Formed by the removal of non-ore material from proto-ore.  e.g. leaching of silica and alkalis from a nepheline syenite may leave behind a surface capping of hydrous aluminum oxides, called bauxite.  e.g. weathering granite  kaolinite.  e.g. laterite can enrich nickel from peridotites. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 7 Australian Laterites. Very large areas are covered by laterite. It is amenable to open pit mining with only truck and shovel, no blasting required.
  8. 8. LATERITE PROFILE On Un-serpentinised Peridotite, Sorowako Red Laterite (Hematite) Yellow Laterite (Limonite) Saprolite zone Bedrock pinnacle Typical laterite profile in a road cut: dark limonite overburden above the red line; limonite low grade to medium grade between the red and the green lines; and saprolite below the green line. At the road level some signs of possible bedrock pinnacles are exposed. Imaginary drill holes A,B,C at about 25 meter spacing in this photo would return completely different profile interpretations in terms of quantity and position of each of the three main layers. This high degree of variability of the laterite adds risk to exploration in the early stage that grade and tonnage estimates will not be representative for economic studies. Only detailed exploration will provide the sampling to reduce this risk. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 8
  9. 9. Laterisation System MgO SiO2 FeO or F2O3 Bedrock Soft Saprolite Hard Saprolite All compositions are shown in terms of the three oxides PATH OF LATERISATION Limonite 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 9
  10. 10. Laterite-type bauxite Bauxite (the principal ore of aluminum) 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 10
  11. 11. Definition: Name: Laterite-type bauxite (simply: Bauxite). Bauxites are:  The source of the world’s aluminum.  Is an aluminum ore and is not actually a mineral.  Gibbsite Al(OH)3 is the main mineral in Bauxite ore.  is formed in residual deposits; at or near the surface under tropical or Subtropical conditions of weathering.  Concentrated in the tropics because that is where lateritic weathering occurs.  Occurs in many countries of the tropical belt.  Found in present-day temperate conditions, such as France, China, Hungary, and Arkansas, where the climate was tropical when the bauxites formed.  Not found in glacial regions.  Glaciers scrape off the soft surface materials. 1) Laterite-type Bauxite 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 11  Although aluminium is the most abundant metal in the earth's crust and the third most abundant element, it occurs mainly in combinations that so far have defined commercial extraction.  It is an important constituent of all clays and soil and of the silicates of common rocks.
  12. 12. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 12
  13. 13. Bauxite – associated with tropical climates 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 13
  14. 14. Bauxite Aluminum ore, called bauxite, is most commonly formed in deeply weathered volcano.oregonstate.edu 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 14
  15. 15.  Shape and Form: 1) Pocket Deposit : pocket; hole (ex. Jamaica & South Europe} 2) Blanket deposits: Irregular blankets several meters to tens of meters thick on top of their parent rock (usually but not always){ ex. Australia, Guyana, Surinam}. 3) Detrital Deposits : Accumulate in high slope land and inclined bed 4) Mixed 1, 2 and 3 (ex.Blanket & Detrital Deposits ; Arkansas}  Age: mostly post-Mesozoic.  More than 90 % of all known bauxite deposits formed during the last 60 million years,  All of the very large bauxite deposits formed less than 25 million years ago.  Mined by open pit method.  Main producers: Australia, Guinea, Jamaica, Brazil, India, Surinam and Balkan Republics.  Largest producers are Australia, Jamaica and Guinea. Characteristics: 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 15
  16. 16. Bauxite in Jamaica 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 16 Pocket Deposit Jamaica & South Europe Blanket Deposit Australia, Guyana, Surinam Blanket & Detrital Deposits Arkansas Shape and Form
  17. 17. Constitution of Bauxite Mineralogy:  Bauxite is an aluminum ore and is not actually a mineral.  The present usage of the term, both minerlogically and in commerce is to designate a commonly occurring substance that is a mixture of several hydrated aluminium oxides with considerable variation in alumina content.  It is a hardened and partly crystallised hydrogel that consists of variable proportions of the minerals gibbsite (Al(OH)3) or hydrargillite, and boehmite {AlO(OH)} and its dimorphous form {i.e. diaspore AlO(OH)}, together with hematite, the clay mineral kaolinite and small amounts of anatase (TiO2).  Impurities are invariably present in the form of halloysite, kaolinite, nontronite, and iron oxides; rarely, bauxite contains octahedrite.  Typical bauxite contains:  35 to 65% Al2O3  2 to 10 % SiO2  2 to 20% Fe2O3  1 to 3 % TiO2  10 to 30% combined water.  For aluminium ore: bauxite should contain preferably at least 35% Al2O3 and less than 5% SiO2, 6% Fe2O3 and 3% TiO2.  For the chemical industry: the percentage of silica is less important, but iron and titanium oxides should not exceed 3% each; and  For abrasive use: SiO2 and Fe2O3 should be less than 6% each.  Commercial bauxite occurs in three forms:  Pisolitic or oolitic, in which the kernels are much as a centimeter in diameter and consist principally of amorphous trihydrate;  Sponge ore (Arkansas), which is porous, commonly retains the texture of the source rock, and is composed, mainly of gibbsite; and amorphous or clay ore. All three may be intermingled 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 17  Gibbsite: Al(OH)3  Diaspore : AlO(OH)  Boehmite: AlO(OH)  Kaolinite: Al2Si2O5(OH)4  Halloysite: Al2Si2O5(OH)4•2H2O  Montmorillonite: (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2•nH2O
  18. 18. Gibbsite Al(OH)3 Diaspore AlO(OH) Bauxite Al-hydroxide* *hybrid mix of diaspore, gibbsite, and boehmite (AlO(OH)) Gibbsite-type – dioctahedral sheets (only two of three octahedral sites are filled). (OH)- main anionic group forming octahedrally coordinated sheets with weak bonds between 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 18
  19. 19. Types of deposits: 1) High level or upland bauxites 2) Low level peneplain bauxites 3) Karst Bauxites  Directly on volcanic or plutonic rocks, no clay body in between.  < 30 m in thickness  In tropical and subtropical climates  Porous and friable, often with relict textures  Predominated by Gibbsite  Weathering controlled by structures in parent rocks  Examples: Ghana and Guinea  Somewhat transported, separated from their parent rock by kaolinitic under clay.  ~ 9 m thick.  Along tropical coastlines  Pisolitic textures.  Associated with detrital bauxites produced by fluvial and marine activity.  Examples: South America, Australia, and Malaysia.  Oldest known.  In Eastern Europe.  On top of karst surfaces in limestone and dolomite.  Structureless, earthy, concretions, …. variable textures!  Predominated by Boehemite. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 19
  20. 20. Fig. 6. Photomicrographs of selected samples from the Mandan bauxite deposit. A. Spheroidal ooids with core filled by other ooids. B. Porous matrix filled with calcite and fracture filled by kaolinite. C. Aggregation of pisolites with light- color matrix, which is interpreted as due to deferrification process in the bauxite deposit. D. Pisolite with a core of boehmite surrounded by a cortex of alternating hematite. E. Euhedral pyrite in gray bauxite. F. Euhedral and framboidal pyrite in gray bauxite. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 20
  21. 21. Origin and Mode of formation Conditions necessary for formation of bauxites: Mode of formation: 1) favorable parent rock. 2) porosity. 3) high rainfall with intermittent dry spells. 4) good drainage. 5) tropical warm climate. 6) low relief. 7) long period of exposure. 8) vegetation. 9) Low Fe, Ti, alkalis, and alkali earths 1) Weathering. 2) In situ leaching of elements and enrichment of residue in Al. 3) Possible erosion and redeposition? 4) Addition of eolian dust. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 21 Formation of Bauxite deposit is formed by lateritization (intense chemical weathering in hot, wet, tropical areas) of various silicate rocks such as granite, gneiss, basalt, and shale.
  22. 22. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 22 Includes Bauxite enrichment from Laterites In situ leaching of elements and enrichment of residue in Al. Mode of Formation (Cont.)
  23. 23. Steps:  Al is abundant in earth (after O and Si). But, binds very strongly to O, poorly soluble = difficult to process.  Bauxite is an accumulated product of peculiar weathering of aluminium silicate rocks lacking in much free quartz, lie silicates are broken down; silica is removed; iron is partly removed; water is added; and alumina, along with titanium and ferric oxide (and perhaps manganese oxide), becomes concentrated in the residuum.  leaching in tropical/subtropical where abundant rainfall (leaching), near neutral pH where Al least soluble.  Highly soluble materials like Na, K, Ca leach first.  Then Mg and others.  Formation of kaolinite from K-feldspar, also production of gibbsite (bauxite) as H2SiO4 drops as SiO2 is leached (Kaolinite ↔ Gibbsite + Silicic Acid). 4KAlSi3O8 (Orthoclase) + 4H2CO3 (Carbonic acid) + 18H2O (water) ↔ Al4Si4O10 (OH)8 (Kaolinite-Clay) + 4K+ (Potassium ions) + 4HCO3 - (Carbonate ions) + 8H4SiO4 + (Silicic acid) Al converted mainly to kaolinite (often from feldspars: see phase diagrams and reactions, compare phase diagram to le Chatelier principle).  Formation of kaolinite from K-feldspar, also production of gibbsite (bauxite) as H2SiO4 drops as SiO2 is leached (Kaolinite ↔ Gibbsite + Silicic Acid)  Progressive dissolution of silica from clays in wet soils will eventually turn the: Kaolinite {Al4Si4O10(OH)8 }  into Gibbsite {Al(OH)3} Gibbsite (Al(OH)3) boehemite {AlO(OH))+ diaspore (AlO(OH)} • Basic reaction: Al2O3  2Al + 3O  Cathodic reaction: 2Al3+ + 6e-  2Alo  Anodic reaction : 3O2-  1.5O2 + 6e-  Eventually, Si in kaolinite can leach out, leaving Al oxides and hydroxides (gibbsite=Al(OH)3, boehmite=AlO*OH).  Where conditions are slightly more acidic, Fe may also leach (narrow zone), or, more likely, if rocks are initially low in Fe.  Can be redeposited  these soils become bauxite, a major ore of aluminum.  This produces more pure Al ore.  low relief = slow erosion compared to rate of chemical leaching common pisolitic texture, consequence of insitu process of phase transformation. Note: Bacteria may have played a part in bauxite formation. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 23 Mode of Formation (Cont.)
  24. 24. Mode of Formation (Cont.) 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 24 Al(OH)3 Insoluble
  25. 25. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 25 World bauxite reserves 2010
  26. 26. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 26 $5.6B Data in thousands of metric tons Al metal Data in thousands of metric tons dry ore – Bauxite $120B $63B $8B $2.9B
  27. 27. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 27
  28. 28. Clay (Kaolinite) Deposits 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 28
  29. 29. Clay (Kaolinite) Deposits Formed by Residual Concentration Residual clays can be classified as follows: 1) Kaolins, white in colour, and usually white burning: a) Veins, derived from weathering of dikes. b) Blanket deposits, derived from areas of igneous or metamorphic rocks. c) Replacement deposits, such as indianite. d) Bedded deposits, derived from feldspathic sandstones. 2) Red-burning residuals derived from different kinds of rocks. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 29
  30. 30. Source Materials The chief source rocks of residual clays are crystalline rocks, more especially the silicic granular rocks that are rich feldspars and low in iron minerals, such as granite and gneiss.  Basic igneous rocks yield much ferric oxide, which stain the clay, often rendering it useless.  Feldspar-rich pegmatite yield Dike-like masses of high-grade white kaolin that is generally very low; in iron and other impurities deleterious chinaware manufacture.  Syenites yield excellent clay.  Limestones, after long-continued solution erosion, leave a mantle of insoluble clayey impurities that are used for brick clays.  Shale, which is largely made up of clay minerals, is used as clay material, but weathering often yield a purer product.  Sericitized igneous rocks yield clay. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 30
  31. 31. Mode of Formation Clay formation results from normal weathering processes. Vegetation plus the atmosphere supply the necessary CO2, and it is noteworthy that good clays commonly underlie swamps. Organic compounds:  serve to remove coloring materials and produce white clays.  change iron from the insoluble ferric (Fe3+) to the soluble ferrous (Fe2+) state, permitting its removal in solution thereby bleaching the clay. The formation of clay from silicate minerals is essentially a breaking down of the silicates to form hydrous aluminium silicates and the removal of the soluble silica and alkalis in solution. Some free quartz will remain and must be extracted to obtain pure clay. The alteration of orthoclase, for example, yields kaolinite, potassium carbonate, and silica. The last two are removed in solution and the kaolinite persists. 4KAlSi3O8 (Orthoclase) + 4H2CO3 (Carbonic acid) + 18H2O (water) ↔ Al4Si4O10 (OH)8 (Kaolinite) + 4K+ (Potassium ions) + 4HCO3 - (Carbonate ions) + 8H4SiO4 + (Silicic acid) Formation of kaolinite from K-feldspar, also production of gibbsite (bauxite) as H2SiO4 drops as SiO2 is leached (Kaolinite ↔ Gibbsite + Silicic Acid). Kaolinite deposits also result from hydrothermal action. Kaolinite, dickite, and montmorillonite occur in the halo of hydrothermal rock alteration tint surrounds many hydrothermal ore deposits, particularly porphyry copper deposits. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 31
  32. 32. 2) Nickel Laterite Deposits 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 32
  33. 33. Nickel Deposits Formed by Residual Concentration  Many mafic/ultramafic igneous rocks are known to contain very small quantities of nickel in some unknown form but presumably held in the silicate lattices.  Rocks containing nickel are broken down, decomposed, and lose silica by intense tropical and Subtropical weathering to form a soil layer.  Water flowing through the soil layer leaches nickel and other metals from the soil.  Nickel, iron and magnesium oxides and silicates precipitate from water into the soil layer, the laterite. Nickel laterite ore deposits  Residual soils  Developed over mafic/ultramafic rocks through processes of chemical weathering and supergene enrichment under tropical climatic conditions  the surficial, deeply weathered residues formed on top of ultramafic rocks that are exposed at surface in tropical climates.  Found widely in New Caledonia, Cuba, , Celebes, Borneo, Australia, Papua New Guinea, the Philippines, Indonesia, Brazil, and Venezuela,.  Are estimated to comprise about 73% of the world continental nickel resource. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 33
  34. 34. Nickel laterite deposits Mg RICH “ULTRAMAFIC” ROCK 0.3% Ni Olivine and pyroxene (silicate minerals) SAPROLITE ZONE 1.5 - 2.5% Ni Serpentine (hydrated silicate) Goethite (hydrated oxide) LIMONITE ZONE 1- 2% Ni Deep downward penetration of water producing weathering The process of oxidation and weathering depletes the original mafic rock of Mg and Si, and concentrates Fe and Ni in the weathered zone. Near surface upward evaporation of water precipitates Fe, Ni oxide OREBODY  Ultramafic rock - igneous rocks formed from magma with very low concentrations of quartz (SiO2). Peridotite is a common ultramafic rock type which contains olivine, a greenish-gray mineral, with magnesium and nickel.  Rocks containing nickel are broken down by intense weathering to form a soil layer :  Weathering begins on joints and fractures in the rock to form large blocks or boulders with a thin soil layer.  Further weathering and biological processes thicken the soil layer.  Water flowing through the soil leaches nickel, iron, and magnesium (and other metals) from the soil.  The metals (nickel, iron, magnesium and other) then precipitate from water as oxides, hydroxides and silicates in different parts of the soil layer as laterite. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 34
  35. 35. Mineralogy: • Formerly, several species were thought to exist, such as genthite, pirnelite, nepouite, connarite, garnierite, and noumeite. • In several places, "garnierite" derived from serpentinized peridotite, has undergone sufficient residual concentration on the surface to form workable deposits of nickel ore. Types of lateritic nickel ore deposits Three kinds of lateritic nickel ore can be distinguished: 1) Limonite (oxide) types (or Oxide Ni deposits): Ni as hydroxide in the ferruginous zone 2) Clay silicate deposits: Ni as clay silicate 3) Saprolite types (or Hydrous silicate deposits): Ni as hydrous-silicate in saprolite Mineralogy and Types of lateritic nickel ore deposits 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 35
  36. 36. http://en.wikipedia.org/wiki/File:River_South_ New_Caledonia.JPG.JPG A Creek in southern New-Caledonia. Red colours reveal the richness of the ground in iron oxides, and nickel. Limonite zone Idealized cross section of tropical laterite-saprolite nickel profile. Vertical scale is in terms of meters; horizontal scale is in terms of kilometers. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 36
  37. 37. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 37 Ni-rich Laterites Papua New Guinea (PNG)
  38. 38. World Nickel Laterite Deposits Cuba Dominican Republic Brazil Columbia Guatemala Albania Greece Philippines Indonesia PNG New Caledonia Australia Venezuela BurmaIndia Madagascar Producing Countries Non Producing Countries Ivory Coast Zimbabwe Ethiopia Burundi 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 38
  39. 39. World Nickel Laterite Resources (Distribution by Contained Nickel) Caribbean 25% New Caledoni a 20% Indonesi a 16% Philippine s 11% Australia 8% Africa 8% America 8% Other 4% Mt Ore % Ni Contained Nickel Mt Relative % 10,382 1.32 140 69% WORLD’S LAND-BASED Ni RESOURCES 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 39 Ni Market Drivers More nuclear power? Wind farms? Hybrid/electric cars? NiMH vs Li-Ion? Ni: metric tonnes
  40. 40. WORLD Ni PRODUCTION & RESOURCES PRIMARY Ni PRODUCTION WORLD Ni RESOURCES SULPHIDE LATERITE 60% 40% SULPHIDE LATERITE 30% 70% Note: Sulphide nickel deposits : Nickel as nickel sulphide  pentlandite, millerite) 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 40
  41. 41. Processing of Ni Laterites Nickel ores processed through three processes: 1) Pyro-metallurgical (smelting) processing (Ore is melted)  Ferro-nickel (Ferro-Nickel Product 20 – 50% Ni)  Ni-matte ((Nickel-Matte Product 78% Ni)  Ni Pig Iron 2) Hydro-metallurgical processing (Leaching by acid)  PAL (Pressure acid leaching) – HPAL  AL (Atmospheric Leaching)  Heap Leaching 3) Combined pyro and hydro process (Caron) (Ore is reduced at high temperature, then leached) Note: The selection of processing technology must consider: • Ore characteristic (Chemistry and Mineralogy) • Ni/Co grades (include potential upgrading) • Metal recovery • Mineability (Ore thickness and continuity) • Capital and Operating costs (potential hydro- electric power, Residual Storage Facility, Water source, Limestone source, Existing infrastructure, etc) • Market demand Good Hydro Hydro Hydro- Pyro Fair Hydro Hydro- Pyro Hydro- Pyro Poor Pyro Pyro Poor Fair Good LimoniteDevelopment Saprolite Development Hydro vs Pyro 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 41
  42. 42. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 42
  43. 43. Example: Ni-laterites, Ni in soils in east Albania Simplified tectonic map of central part of Albania (Hoxha, 2001). B: Distribution of ophiolites along of the Balkan Peninsula (after Bortolotti et al., 1996). 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 43
  44. 44. Ni-laterites, Ni in soils in east Albania Geological map of the Prrjenas intramontane basin (from the Geological Map of Albania 1:200,000). Noticeable that the chain of Ni-laterite deposits follows always the boundary of serpentinite and the cover Cretaceous limestone. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 44
  45. 45. Ni-laterites, Ni in soils in east Albania Panoramic view of the Prrenjas intramontane basin with indication of the position of the village, the mines and the typical lithologies of the major chines. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 45
  46. 46. Synoptic profiles of major types of the Ni-laterite deposits of the Balkan Peninsula. Compiled according to: Ivanov, 1960; Augusthitis (1962); Arkaxhiu and Kici (1990); Skarpelis et al., 1996; Skarpelis, 1997; Eliopoulos and Economou-Eliopoulos, 2000; Peci and Grazhdani, 2001 and field observations of ID in 2004. (a)-(d): deposits of Cretaceous age. The first column (a) represents the most typical profile; the laterite deposited more-or-less autochtonously on the weathered ultrabsic rock. (b): The lateritic material was redeposited and covers slightly- or unwathered ultrabasite. (c) & (d): The lateritic material was resedimented on Mesozoic limestone. (e): the footwall and henging wall of the deposit is bordered by faults, the stratigraphic age of the cover sequenci is unknown. (f): Paleogene cover with alternating deposition of lateritic and siliciclastic material. (g): Deposits in the Miocene sequences. Ni-laterites, Ni in soils in east Albania 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 46
  47. 47. Ni-laterites, Ni in soils in east Albania Geological setting of laterite ore deposits of the Edessa are, Greece a: Messimeri; b: Vrita; c: Flamuria (from Michaildis, 1990). These profiles show how different are the stratigraphic successions even within a small area further these profiles are representing well the characteristic tilting and thrusting. no detectable overprint (e.g.Prrenjas) weak, diagenetic overprint (e.g. Bitincka) low-grade metamorphism (e.g. Edessa) medium-high-grade metamorphism (e.g. Samos) nontronite and clay minerals, high porosity, loose structure garnierite & other Ni-hydro- silicates, veins, compaction Ni-alkali amphibole, stilpnomelane, epidote, reaction rims on Cr-spinell Ni-silicates, Ni- tourmaline, corund,staurolite, gahnite Diagenetic-metamorphic overprint Major stages of post-sedimentary overprint of the laterite deposits of the Balkan Peninsula and the Greek archipelago. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 47
  48. 48. Ni-laterites, Ni in soils in east Albania The base of the Bitincka laterite layer shows a complex geometry, partly due to the deposition on the irregular surface of the serpentinite, but a young faulting has also some role. The immediate cover sequence in Bitincka. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 48
  49. 49. Ni-laterites, Ni in soils in east Albania Serpentinite pebbles and clasts in protolaterite – Kurbneshi, northern Albania. Limestone fragments in Ni-laterite – Katjeli. Ni-silicate veins in the Ni-laterite. Ni-laterite mines and dumps are throning above the settlements. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 49
  50. 50. Ni-laterites, Ni in soils in east Albania Microscopic reflected light image of a weathered chromite grain (gray) which is replaced along cracks by hematite (white). Width of picture is ca. 270 µm (from Augustithis, 1962). from Michailidis et al. (1985) 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 50
  51. 51. Sample Problem Answer:  Distinguish between weathering and depositional methods of the formation of economic mineral deposits.  Distinguish between depositional methods of the formation of economic mineral deposits in arid and tropical (or subtropical) environments.  Distinguish between different residual methods of the formation of economic mineral deposits.  Distinguish between evaporation and depositional methods of the formation of economic mineral deposits. 22 November 2015 Prof. Dr. H.Z. Harraz Presentation Residual (or laterite) Mineral Deposits 51
  52. 52. 2-5 Geophysical Surveying END OF TOPIC 8

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