Topic 8: Residual (or laterite) Mineral Deposits                    A short series of lectures prepared for the           ...
Outline of Topic 8:         Residual Concentration         Definition of Residual mineral deposits         Definition o...
Topic 8: RESIDUAL (or LATERITE) MINERAL DEPOSITSResidual Concentration: Result in the accumulation of valuable minerals w...
Definition of Residual mineral deposits  Residual mineral deposits formed and concentrated by chemical     weathering rea...
Definition of Laterites Laterite - the resulting soil layer, typically red in color due to the  presence of iron oxides a...
Laterite ProfileOn Un-serpentinised Peridotite, Sorowako                                                         Typical l...
Laterite/Bauxite Conditions Climate Parent Rock Composition Subtle Eh-pH Controls                                      ...
Example:   Formed by the removal of non-ore material from proto-ore.       e.g. leaching of silica and alkalis from a nep...
Laterite-type bauxite                          Bauxite                    (the principal ore of aluminum)                 ...
1) Laterite-type Bauxite  Although aluminium is the most abundant metal in the earths crust and the third most abundant e...
Bauxite – associated with tropical climates                      Prof. Dr. H.Z. Harraz Presentation 13 December 2012      ...
Aluminum ore, called bauxite, is most                                                    commonly formed in deeply weather...
Characteristics:  Shape and Form:      1) Pocket Deposit : pocket; hole (ex. Jamaica & South Europe}      2) Blanket depo...
Bauxite in Jamaica                                                Shape and Form                                          ...
Constitution of BauxiteMineralogy:                                                         Typical bauxite contains: Bau...
Gibbsite Al(OH)3Gibbsite-type – dioctahedralsheets (only two of threeoctahedral sites are filled).(OH)- main anionic group...
Types of bauxite deposits:    1) High level or upland         2) Low level peneplain                      3) Karst Bauxite...
Fig. 6. Photomicrographs of                                                   selected samples from the Mandan            ...
Origin and Mode of FormationFormation of Bauxite deposit is formed by lateritization (intense chemical weatheringin hot, w...
Mode of Formation (Cont.)                                    In situ leaching of elements and enrichment Soil             ...
Mode of Formation (Cont.)Steps: Al is abundant in earth (after O and Si). But, binds very strongly to O, poorly soluble =...
Mode of Formation (Cont.)         Bentomitic ClayAsh                        Bauxite                            Gibbsite   ...
World bauxite reserves 2010                           Prof. Dr. H.Z. Harraz Presentation13 December 2012                  ...
Data in thousands of metric tons dry ore – Bauxite                                $5.6B                                   ...
Prof. Dr. H.Z. Harraz Presentation13 December 2012                                             25                   Residu...
Clay (Kaolinite) Deposits                            Prof. Dr. H.Z. Harraz Presentation13 December 2012                   ...
Clay (Kaolinite) Deposits Formed by Residual Concentration Residual clays can be classified as follows:  1) Kaolins, whit...
Mode of FormationClay formation results from normal weathering processes.Vegetation plus the atmosphere supply the nece...
2) Nickel Laterite Deposits                      Prof. Dr. H.Z. Harraz Presentation13 December 2012                       ...
2) Nickel Laterite Deposits Many mafic/ultramafic igneous rocks formed from magma with very low concentrations of quartz ...
Deep downward                         Near surface upwardpenetration of water                  evaporation of waterproduci...
Mineralogy and Types of lateritic nickel ore deposits      Mineralogy:                     Genthite {Ni3Si2O5(OH)4}      ...
World Nickel Laterite Deposits                                                                            Albania         ...
World Nickel Laterite Resources                      (Distribution by Contained Nickel)                                   ...
Processing of Ni Laterites                                                                                                ...
Prof. Dr. H.Z. Harraz Presentation13 December 2012                                             36                   Residu...
Example: Ni-laterites, Ni in soils in east Albania   Simplified tectonic map of central part of Albania (Hoxha, 2001). B: ...
Ni-laterites, Ni in soils in east Albania Geological map of the Prrjenas intramontane basin (from the Geological Map of Al...
Ni-laterites, Ni in soils in east Albania Panoramic view of the Prrenjas intramontane basin with indication of the positio...
Ni-laterites, Ni in soils in east AlbaniaSynoptic profiles of major types of the Ni-laterite deposits of the Balkan Penins...
Ni-laterites, Ni in soils in east Albania                   Diagenetic-metamorphic overprintno detectable       weak, diag...
Ni-laterites, Ni in soils in east AlbaniaThe base of the Bitincka laterite layer shows a                        The immedi...
Ni-laterites, Ni in soils in east AlbaniaSerpentinite pebbles and clasts inprotolaterite – Kurbneshi, northern Albania.   ...
Ni-laterites, Ni in soils in east Albania                                                            Microscopic reflected...
END 2-5 TOPIC 8 Surveying    OF Geophysical
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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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  1. 1. Topic 8: Residual (or laterite) Mineral Deposits A short series of lectures prepared for the Fourth year of Geology, Tanta University 2012- 2013 by Hassan Z. Harraz hharraz2006@yahoo.com Prof. Dr. H.Z. Harraz Presentation13 December 2012 1 Residual (or laterite) Mineral Deposits
  2. 2. Outline of Topic 8:  Residual Concentration  Definition of Residual mineral deposits  Definition of Laterites  Laterite Profile  Laterisation system  Laterite/Bauxite Conditions 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 We will explore all of the above in Topic 8 Prof. Dr. H.Z. Harraz Presentation13 December 2012 2 Residual (or laterite) Mineral Deposits
  3. 3. Topic 8: RESIDUAL (or LATERITE) MINERAL DEPOSITSResidual Concentration: Result in the accumulation of valuable minerals when 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. 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. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 3 Residual (or laterite) Mineral Deposits
  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.  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.  Resource from residual mineral deposits: Al (Bauxite), Ni (Nickeliferous- laterite), Co, Ni, Cu, Fe and kaolinite. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 4 Residual (or laterite) Mineral Deposits
  5. 5. Definition of Laterites 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 subtropical and tropical Red Laterite (Hematite) 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. Yellow Laterite (Limonite) 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, Saprolite zone titanium, copper and gold 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. Laterites are source of metals: Schematic soil profile in a laterite showing  Ni, Co, Cr, Fe (from laterites derived from ultramafic rocks) the progression of weathering effects on rock. Some commodities, such as aluminum  Al (from laterites derived from aluminous rocks) and nickel, are enriched by weathering. Modified slightly from Elias (2002). Prof. Dr. H.Z. Harraz Presentation 13 December 2012 5 Residual (or laterite) Mineral Deposits
  6. 6. Laterite ProfileOn Un-serpentinised Peridotite, Sorowako 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;Red Laterite (Hematite)  Saprolite below the green line.  At the road level some signs of possible bedrock pinnacles are exposed. Yellow Laterite (Limonite) Laterisation SiO2 PATH OF System LATERISATION All compositions a re shown in te rms of the thre e oxide s Saprolite zone H a rd Sa prolite Be drock Soft Sa prolite Bedrock pinnacle Limonite MgO FeO or F2O3 Prof. Dr. H.Z. Harraz Presentation 13 December 2012 6 Residual (or laterite) Mineral Deposits
  7. 7. Laterite/Bauxite Conditions Climate Parent Rock Composition Subtle Eh-pH Controls 3  [1],[2]: Al and Fe leached 2 4 1 5  [3],[4]: low solubility so need Fe, Al rich 6 parent material  [5]: enough Fe mobility to form Fe-laterites  [6]: optimal for bauxites Prof. Dr. H.Z. Harraz Presentation13 December 2012 7 Residual (or laterite) Mineral Deposits
  8. 8. 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.Australian Laterites. Very large areas are covered by laterite. It is amenable to open pit mining withonly truck and shovel, no blasting required. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 Residual (or laterite) Mineral Deposits 8
  9. 9. Laterite-type bauxite Bauxite (the principal ore of aluminum) Prof. Dr. H.Z. Harraz Presentation13 December 2012 9 Residual (or laterite) Mineral Deposits
  10. 10. 1) Laterite-type Bauxite  Although aluminium is the most abundant metal in the earths 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.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.  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.  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. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 10 Residual (or laterite) Mineral Deposits
  11. 11. Bauxite – associated with tropical climates Prof. Dr. H.Z. Harraz Presentation 13 December 2012 11 Residual (or laterite) Mineral Deposits
  12. 12. Aluminum ore, called bauxite, is most commonly formed in deeply weathered volcano.oregonstate.edu Bauxite Prof. Dr. H.Z. Harraz Presentation13 December 2012 12 Residual (or laterite) Mineral Deposits
  13. 13. Characteristics:  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, Guyana, Indonesia, Cuba, Philippines, India, Surinam and Balkan Republics.  Largest producers are Australia, Jamaica and Guinea. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 13 Residual (or laterite) Mineral Deposits
  14. 14. Bauxite in Jamaica Shape and Form Pocket Deposit Jamaica & South Europe Blanket Deposit Australia, Guyana, Surinam Blanket & Detrital Deposits Arkansas Prof. Dr. H.Z. Harraz Presentation13 December 2012 14 Residual (or laterite) Mineral Deposits
  15. 15. Constitution of BauxiteMineralogy:  Typical bauxite contains: Bauxite is an aluminum ore and is not actually a mineral.  35 to 65% Al2O3 The present usage of the term, both minerlogically and in  2 to 10 % SiO2 commerce is to designate a commonly occurring substance  2 to 20% Fe2O3 that is a mixture of several hydrated aluminium oxides with considerable variation in alumina content.  1 to 3 % TiO2  10 to 30% combined water. It is a hardened and partly crystallised hydrogel that consists of variable proportions of the minerals gibbsite  For aluminium ore: bauxite should contain preferably (Al(OH)3), boehmite {AlO(OH)} and its dimorphous form at least 35% Al2O3 and less than 5% SiO2, 6% Fe2O3 {i.e. diaspore AlO(OH)}, together with hematite, the clay and 3% TiO2. mineral kaolinite and small amounts of anatase (TiO2).  For the chemical industry: the percentage of silica is Impurities are invariably present in the form of halloysite, less important, but iron and titanium oxides should kaolinite, nontronite, and iron oxides. not exceed 3% each; and  For abrasive use: SiO2 and Fe2O3 should be less than 6% each.  Commercial bauxite occurs in three forms: Gibbsite: Al(OH)3  Pisolitic or oolitic, in which the kernels are much as a centimeter in diameter and consist Diaspore : AlO(OH) principally of amorphous trihydrate; Boehmite: AlO(OH)  Sponge ore (Arkansas), which is porous, commonly retains the texture of the source rock, and is Kaolinite: Al2Si2O5(OH)4 composed, mainly of gibbsite; and amorphous or clay ore. All three may be intermingled Halloysite: Al2Si2O5(OH)4•2H2O Montmorillonite: (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2•nH2O Prof. Dr. H.Z. Harraz Presentation 13 December 2012 15 Residual (or laterite) Mineral Deposits
  16. 16. Gibbsite Al(OH)3Gibbsite-type – dioctahedralsheets (only two of threeoctahedral sites are filled).(OH)- main anionic groupforming octahedrally Diaspore AlO(OH)coordinated sheets with weakbonds between Bauxite Al-hydroxide* *hybrid mix of diaspore, gibbsite, and boehmite (AlO(OH)) Prof. Dr. H.Z. Harraz Presentation 13 December 2012 16 Residual (or laterite) Mineral Deposits
  17. 17. Types of bauxite deposits: 1) High level or upland 2) Low level peneplain 3) Karst Bauxites bauxites bauxites Directly on volcanic or  Somewhat transported,  Oldest known. plutonic rocks, no clay separated from their  In Eastern Europe. body in between. parent rock by kaolinitic  On top of karst surfaces in < 30 m in thickness under clay. limestone and dolomite. In tropical and  ~ 9 m thick.  Structure less, earthy, subtropical climates  Along tropical coastlines concretions, …. variable Porous and friable, often  Pisolitic textures. textures! with relict textures  Associated with detrital  Predominated by Predominated by Gibbsite bauxites produced by Boehemite. Weathering controlled by fluvial and marine activity. structures in parent rocks  Examples: South America, Examples: Ghana and Australia, and Malaysia. Guinea Prof. Dr. H.Z. Harraz Presentation13 December 2012 17 Residual (or laterite) Mineral Deposits
  18. 18. 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. Prof. Dr. H.Z. Harraz Presentation13 December 2012 18 Residual (or laterite) Mineral Deposits
  19. 19. Origin and Mode of FormationFormation of Bauxite deposit is formed by lateritization (intense chemical weatheringin hot, wet, tropical areas) of various silicate rocks such as granite, gneiss, basalt, andshale. Conditions necessary for formation of bauxites: Mode of formation: 1) favorable parent rock. 1) Weathering. 2) porosity. 2) In situ leaching of elements and 3) high rainfall with intermittent dry spells. enrichment of residue in Al. 4) good drainage. 3) Possible erosion and 5) tropical warm climate. redeposition? 6) low relief. 4) Addition of eolian dust. 7) long period of exposure. 8) vegetation. 9) Low Fe, Ti, alkalis, and alkali earths Prof. Dr. H.Z. Harraz Presentation13 December 2012 19 Residual (or laterite) Mineral Deposits
  20. 20. Mode of Formation (Cont.) In situ leaching of elements and enrichment Soil of residue in Al.Profile A B C Water Table Includes Bauxite enrichment from Laterites Prof. Dr. H.Z. Harraz Presentation 13 December 2012 20 Residual (or laterite) Mineral Deposits
  21. 21. Mode of Formation (Cont.)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). 4KAlSi3O 8 (Orthoclase) + 4H2CO3 (Carbonic acid) + 18H2O (water) ↔ Al4Si4O 10 (OH)8 (Kaolinite-Clay) + 4K+ (Potassium ions) + 4HCO 3- (Carbonate ions) + 8H4SiO 4+ (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: 6e-  2Alo 2Al3+ +  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. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 21 Residual (or laterite) Mineral Deposits
  22. 22. Mode of Formation (Cont.) Bentomitic ClayAsh Bauxite Gibbsite Al(OH)3 Insoluble Hematite Prof. Dr. H.Z. Harraz Presentation 13 December 2012 22 Residual (or laterite) Mineral Deposits
  23. 23. World bauxite reserves 2010 Prof. Dr. H.Z. Harraz Presentation13 December 2012 23 Residual (or laterite) Mineral Deposits
  24. 24. Data in thousands of metric tons dry ore – Bauxite $5.6B Data in thousands of metric tons Al metal $8B $2.9B $120B $63B Prof. Dr. H.Z. Harraz Presentation 13 December 2012 24 Residual (or laterite) Mineral Deposits
  25. 25. Prof. Dr. H.Z. Harraz Presentation13 December 2012 25 Residual (or laterite) Mineral Deposits
  26. 26. Clay (Kaolinite) Deposits Prof. Dr. H.Z. Harraz Presentation13 December 2012 26 Residual (or laterite) Mineral Deposits
  27. 27. 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.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. Prof. Dr. H.Z. Harraz Presentation13 December 2012 27 Residual (or laterite) Mineral Deposits
  28. 28. 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 H 2SiO4 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. Prof. Dr. H.Z. Harraz Presentation13 December 2012 28 Residual (or laterite) Mineral Deposits
  29. 29. 2) Nickel Laterite Deposits Prof. Dr. H.Z. Harraz Presentation13 December 2012 29 Residual (or laterite) Mineral Deposits
  30. 30. 2) Nickel Laterite Deposits Many mafic/ultramafic 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, and are known to contain very small quantities of magnesium and nickel 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:  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.  Residual soils  Developed over mafic/ultramafic rocks through processes of chemical weathering and supergene enrichment under tropical and Subtropical 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. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 30 Residual (or laterite) Mineral Deposits
  31. 31. Deep downward Near surface upwardpenetration of water evaporation of waterproducing weathering precipitates Fe, Ni oxide The process of oxidation and Limonite weathering depletes the Goethite Zone original mafic rock of Mg (hydrated oxide) 1- 2% Ni and Si, and concentrates Fe and Ni in the Saprolite OREBODY weathered zone. Serpentine Zone (hydrated silicate) 1.5 - 2.5% Ni Olivine and Mg Rich “Ultramafic” pyroxene Rock (silicate minerals) 0.3% Ni http://en.wikipedia.org/wiki/File:River_South_ New_Caledonia.JPG.JPG Limonite zone A Creek in southern New-Caledonia. Red colours revealDecember 2012 ground in iron oxides, Prof. Dr. H.Z. Harraz Presentation 13 the richness of the 31 and nickel. Residual (or laterite)section of tropical laterite-saprolite nickel profile. horizontal scale Idealized cross Mineral Deposits is in terms of kilometers.
  32. 32. Mineralogy and Types of lateritic nickel ore deposits Mineralogy: Genthite {Ni3Si2O5(OH)4} Pimelite {Ni3Si4O10(OH)2•4(H2O)} Nepouite {Ni3Si2O5(OH)4} Comblainite {Ni6Co2(CO3)(OH)16•4(H2O)} Garnierite {Ni3MgSi6O15(OH)2•6(H2O)}, and Nimite {Ni2.6Mg1.7AlFe3+0.4Fe2+0.3Si3AlO10.3(OH) 7.7}. • 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. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 32 Residual (or laterite) Mineral Deposits
  33. 33. World Nickel Laterite Deposits Albania Greece Cuba India Burma Dominican Republic Ivory Coast Philippines Guatemala Venezuela Ethiopia Columbia Burundi Indonesia Brazil Zimbabwe PNGWorld Ni Resources Madagascar Australia 70% LATERITE Producing Countries PRIMARY Ni PRODUCTION New SULPHIDE Caledonia Non Producing Countries 60% SULPHIDE Note:30% Sulphide nickel deposits : Nickel as LATERITE nickel sulphide (Pentlandite, Millerite) Prof. Dr. H.Z. Harraz Presentation 13 December 2012 33 Residual (or laterite) Mineral Deposits 40%
  34. 34. World Nickel Laterite Resources (Distribution by Contained Nickel) Other Ni: metric tonnes America 4% Caribbean Africa 8% 25% 8% Australia 8% Philippine New s Indonesi Caledoni 11% aWORLD’S LAND-BASED Ni RESOURCES a 16% 20% Mt % Contained Relative Ore Ni Nickel % Ni Market Drivers Mt More nuclear power? Wind farms? 10,382 1.32 140 69% Hybrid/electric cars? NiMH vs Li-Ion? Prof. Dr. H.Z. Harraz Presentation 13 December 2012 34 Residual (or laterite) Mineral Deposits
  35. 35. Processing of Ni Laterites Hydro vs Pyro Nickel ores processed through three processes: Hydro- Good Hydro Hydro 1) Pyro-metallurgical (smelting) processing Pyro Limonite Development (Ore is melted) Hydro- Hydro- Fair Hydro Pyro Pyro  Ferro-nickel (Ferro-Nickel Product 20 – 50% Ni)  Ni-matte ((Nickel-Matte Product 78% Ni) Poor Pyro Pyro  Ni Pig Iron Poor Fair Good 2) Hydro-metallurgical processing (Leaching by acid)  PAL (Pressure acid leaching) – HPAL Saprolite Development  AL (Atmospheric Leaching)  Heap Leaching Note: The selection of processing technology must consider: 3) Combined pyro and hydro process (Caron) • Ore characteristic (Chemistry and Mineralogy) (Ore is reduced at high temperature, then leached) • 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 Prof. Dr. H.Z. Harraz Presentation 13 December 2012 35 Residual (or laterite) Mineral Deposits
  36. 36. Prof. Dr. H.Z. Harraz Presentation13 December 2012 36 Residual (or laterite) Mineral Deposits
  37. 37. 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). Prof. Dr. H.Z. Harraz Presentation 13 December 2012 37 Residual (or laterite) Mineral Deposits
  38. 38. 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. Prof. Dr. H.Z. Harraz Presentation13 December 2012 38 Residual (or laterite) Mineral Deposits
  39. 39. 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. Prof. Dr. H.Z. Harraz Presentation13 December 2012 39 Residual (or laterite) Mineral Deposits
  40. 40. Ni-laterites, Ni in soils in east AlbaniaSynoptic profiles of major types of the Ni-laterite deposits of the Balkan Peninsula. Compiledaccording to: Ivanov, 1960; Augusthitis (1962); Arkaxhiu and Kici (1990); Skarpelis et al., 1996;Skarpelis, 1997; Eliopoulos and Economou-Eliopoulos, 2000; Peci and Grazhdani, 2001 andfield 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 theweathered ultrabsic rock. (b): The lateritic material was redeposited and covers slightly- orunwathered ultrabasite. (c) & (d): The lateritic material was resedimented on Mesozoiclimestone. (e): the footwall and henging wall of the deposit is bordered by faults, thestratigraphic age of the cover sequenci is unknown. (f): Paleogene cover with alternatingdeposition of lateritic and siliciclastic material. (g): Deposits in the Miocene sequences. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 40 Residual (or laterite) Mineral Deposits
  41. 41. Ni-laterites, Ni in soils in east Albania Diagenetic-metamorphic overprintno detectable weak, diagenetic low-grade medium-high-grade overprint overprint metamorphism metamorphism (e.g.Prrenjas) (e.g. Bitincka) (e.g. Edessa) (e.g. Samos)nontronite and garnierite & Ni-alkali amphibole, Ni-silicates, Ni-clay minerals, other Ni-hydro- stilpnomelane, tourmaline,high porosity, silicates, veins, epidote, reaction corund,staurolite,loose structure compaction rims on Cr-spinell gahniteMajor stages of post-sedimentary overprint ofthe laterite deposits of the Balkan Peninsulaand the Greek archipelago.Geological setting of laterite ore deposits of theEdessa are, Greece a: Messimeri; b: Vrita; c:Flamuria (from Michaildis, 1990). These profilesshow how different are the stratigraphicsuccessions even within a small area furtherthese profiles are representing well thecharacteristic tilting and thrusting. Prof. Dr. H.Z. Harraz Presentation13 December 2012 41 Residual (or laterite) Mineral Deposits
  42. 42. Ni-laterites, Ni in soils in east AlbaniaThe base of the Bitincka laterite layer shows a The immediate cover sequence incomplex geometry, partly due to the deposition Bitincka.on the irregular surface of the serpentinite, but ayoung faulting has also some role. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 42 Residual (or laterite) Mineral Deposits
  43. 43. Ni-laterites, Ni in soils in east AlbaniaSerpentinite pebbles and clasts inprotolaterite – Kurbneshi, northern Albania. Limestone fragments in Ni-laterite – Katjeli. Ni-laterite mines and dumps are throning Ni-silicate veins in the Ni-laterite. above the settlements. Prof. Dr. H.Z. Harraz Presentation 13 December 2012 43 Residual (or laterite) Mineral Deposits
  44. 44. 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) Prof. Dr. H.Z. Harraz Presentation13 December 2012 44 Residual (or laterite) Mineral Deposits
  45. 45. END 2-5 TOPIC 8 Surveying OF Geophysical

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