Presentation on theme: "ORE, WASTE and MINERALOGY What is an ore? What is waste? What is the role of mineralogy in MMPE? How do these questions change for different commodities?"— Presentation transcript:
ORE, WASTE and MINERALOGY What is an ore? What is waste? What is the role of mineralogy in MMPE? How do these questions change for different commodities?
Downstream Processing Mine/mill complex – produces ore or concentrate or unrefined metal/product – product transported by airplane, rail, truck or ship to smelter or refinery – if leaching is used at mine/mill, unrefined metal or final product is produced Smelting –pyrometallurgical processing (multi-stage) roasting to partially remove/control sulfur content melting to separate oxides from sulfides (flux and slag) oxidation to remove sulfur and iron need SO 2 control and slag disposal system
Downstream Processing Leaching – hydrometallurgical processing – vat leach, agitation leach, heap leach, in-situ leach – Pressure Oxidation or Biological Leaching –solid/liquid separation or ion adsorption process –solution purification (solvent extraction/ion exchange) –need residue disposal method (dewatering/storage) Refining –electrometallurgical processing electrowinning to recover metals from solution electrorefining to purify unrefined metal treatment of slime deposits for PMs recovery
What is an Ore? Definition: An ore is a mass of mineralization within the Earth's surface which can be mined - at a particular place; - at a particular time; - at a profit.
What is Waste? Definition: Waste is mineralized rock that is removed from a mine to provide access to an underlying or nearby orebody containing at least one mineral of value. Types of Waste: - footwall material (typically barren material) - hangingwall material (typically contains sulfides) - gangue material contained within the ore
What is Waste? Waste rock can become ore at some later time. - metal/commodity prices can change - other values are discovered within the waste - new technology is developed - environmental protection costs become too high - ore has been exhausted; too costly to close mine
Mineralogy in Mineral Processing Types of minerals in the ore have major impact on operation and control of the processing plant. - relative abundance of ore minerals - feed grade and concentrate grade - types of gangue minerals - slime content (clays, etc.) - pH effects (alkali rock) - pyrite and pyrrhotite (iron sulfides) - association of ore and gangue minerals - liberation characteristics - disseminated vs. massive
Process Mineralogy - establish regular mineralogical analysis of mill feed and other process streams - perform a size-by-size analysis of rock and ore mineral contents and associations - relative abundance - free/locked ratios of grinding circuit streams - perform metallurgical testwork on ore samples containing different mineralogy Virtual Atlas of Opaque and Ore Minerals in their Associations http://www.smenet.org/opaque-ore/
Process Mineralogy - establish metallurgical performance of each process stage for each ore mineral type - determine size ranges where losses occur and examine minerals responsible for these losses - establish impact of impurities on product quality - use all the above information to decide on process changes to improve plant performance with respect to recovery and product quality
Copper Ores Minerals: Sulfides Oxides chalcopyrite - CuFeS 2 cuprite - Cu 2 O bornite - Cu 4 FeS 5 malachite - Cu 2 CO 3 (OH) 2 covellite - CuS pseudomalachite - Cu 5 (PO 4 ) 2 (OH) 4 chalcocite (Cu 2 S) azurite - Cu 3 (CO 3 ) 2 (OH) 2 cubanite (CuFe 2 S 3 ) chrysocolla - CuSiO 3 ·nH 2 O - (Cu,Al) 2 H 2 Si 2 O 5 (OH) 4 ·nH 2 O Gangue Minerals: pyrite quartz feldsparssilicates clays arsenopyrite Mn-wad calcitedolomite
Copper Ores Ore Types: Porphyry: igneous rock of large crystal size (phenocrysts) embedded in a ground mass. Typical mineralization is disseminated chalcopyrite with molybdenite (MoS). Massive: pyrite/pyrrhotite host with chalcopyrite, pentlandite, sphalerite, arsenopyrite, galena. Vein-type: quartz host with veins of chalcopyrite, chalcocite and pyrite
Copper Ores Problems: Liberation: fine grinding may be required. Recovery: oxide/sulfide ratio changes, presence of slime particles, poor recovery of coarse copper minerals. Product: poor liberation, presence of As, Bi, Pb Quality high %H 2 O, variable Cu grade Separation: poor distribution of Co, Zn, Pb, etc.
Copper Ores Anhedral chalcopyrite (yellow, top right) is inter-grown with quartz (light grey, right centre). Pounded to euhedral rutile (grey-white, centre left) is disseminated throughout the host rock. The poorly polished dark grey gangue is phyllosilicate. - El Salvador, Chile
Nickel Ores Minerals: pentlandite (NiFeS) chalcopyrite (CuFeS 2 ) Gangue Minerals: pyrrhotite (Fe x S y where x:y = 0.9-1.1) quartzfeldspars silicatesclays Mn-wadcalcite
Nickel Ores Ore Types: Massive: pentlandite and chalcopyrite in relatively equal quantities in massive pyrrhotite (Fe x S y ). Massive: low copper content in pyrrhotite host. Massive: presence of clay slimes, talc chalcopyrite/pentlandite with pyrrhotite
Nickel Ores Problems: Ni-associations: 3 types - as pentlandite - solid-solution in pyrrhotite - "flame" pentlandite in pyrrhotite Liberation: fine grinding may be required for "flame" pentlandite. Recovery: solid-solution losses. magnetic vs. flotable pyrrhotite Product: clay contamination Quality high %H 2 O, variable Cu/Ni grade
Nickel Ores Problems: Cu-Ni separation: - at milling stage - at the smelting stage - at the matte separation stage Pyrrhotite - magnetic (low intensity) for Recovery: monoclinic FeS (x:y > 1.0) - flotation for hexagonal FeS (x:y < 1.0) Synthetic Minerals: heazlewoodite (Ni 3 S 2 ) chalcocite (Cu 2 S) Fe-Ni alloy (PMs)
Nickel Ores Chalcopyrite, pyrrhotite, pentlandite, and cubanite - Stillwater, Montana, USA Notice flame pentlandite in chalcopyrite
Nickel Ores Pyrrhotite (brown) has pentlandite (light brown, higher reflectance, centre) exsolution bodies as flames, aligned along (0001). Minor amounts of chalcopyrite (yellow, centre right) are associated with cleavage and fractures within pyrrhotite. Silicates are black. 125µm
Nickel Ore Rhomb-shaped areas of deeply etched hexagonal pyrrhotite are surrounded by more lightly etched monoclinic pyrrhotite, which is the main phase. Very lightly etched monoclinic pyrrhotite (pale brown, bottom right) has a rim of granular pentlandite (light brown, higher reflectance). Pyrrhotite is intergrown with chalcopyrite (yellow, centre) and encloses magnetite (grey, top left).
Lead/Zinc Ores Minerals:galena ( PbS ) sphalerite ( Zn x Fe y S ) where x:y = 0.0-0.1 ) marmatite ( high-Fe sphalerite ) anglesite ( PbSO 4 ) cerrusite ( PbCO 3 ) smithsonite ( ZnCO 3 ) hydrozincite ( Zn 5 (CO 3 ) 2 (OH) 6 ) hemimorphite ( Zn 4 Si 2 O 7 (OH) 2 ·H 2 O ) Gangue Minerals: pyrite/marcasite (FeS 2 ) quartz pyrrhotite (Fe x S y ) feldspars silicates clays Mn-wad calcite/dolomite/limestone
Lead/Zinc Ores Ore Types: Massive: galena and sphalerite in a variety of relative quantities in massive pyrite/marcasite (FeS 2 ). Massive: carbonate-hosted ore - Mississippi Valley. Massive: presence of clay slimes, talc galena/sphalerite with pyrrhotite
Lead/Zinc Ores Ore Types: Pb/Zn: galena, sphalerite and pyrite Cu/Pb: chalcopyrite, galena and pyrite Cu/Zn: chalcopyrite, sphalerite and pyrite Cu/Pb/Zn: chalcopyrite, galena, sphalerite and pyrite
Lead/Zinc Ores Problems: Pb-Zn separation: - two-stage flotation - differential (Pb first/Zn second) Cu-Pb-Zn ores: - combined bulk/selective and differential flotation - Cu/Pb bulk followed by Zn float Pb-Zn oxide flotation: use of sulfidizing agents
Lead/Zinc Ores Problems: Zn depression: ZnS is readily activated by Cu ions Cu/Pb separation: essential to avoid smelter penalties Liberation: difficult to assess without mineralogy Product: Zn conc > 55-58%Zn Quality Pb conc > 60-65%Pb Cu conc > 25%Cu
Copper/Lead/Zinc Ores Euhedral arsenopyrite (white, high reflectance, left) is inter- grown with galena (light blue- white with triangular cleavage pits, centre), chalcopyrite (yellow, centre) and sphalerite (light grey, centre right), with fine chalcopyrite inclusions (top left) or submicroscopic chalcopyrite (grey to brown-grey, centre right). A lath of poorly polished molybdenite (light grey, centre) is enclosed within chalcopyrite and galena and has partially rimmed arsenopyrite (bottom right). Minor amounts of rutile (light grey) form acicular crystals within the gangue (right centre). Black areas are polishing pits.
Copper/Lead/Zinc Ores Reniform (kidney-shaped) sphalerite (light grey, centre) is interbanded with galena (white, centre bottom) and chalco- pyrite (yellow) in successive growth rings. Chalcopyrite in the centre of the right sphalerite Has replaced poorly crystalline pyrite (white, top right). Chalcopyrite can be seen to have higher relief than galena (bottom left). The gangue (dark grey) is sulfate. Black areas are polishing pits.
Lead/Zinc Downstream Processing Simplified Lead Extraction and Refining
Lead/Zinc Downstream Processing Simplified Zinc Extraction and Refining
Iron Ores Minerals: hematite (Fe 2 O 3 ) magnetite (Fe 3 O 4 ) martite (Fe 2 O 3 :Fe 3 O 4 ) goethite/limonite (Fe 2 O 3 ·nH 2 O) siderite (FeCO 3 ) ilmenite (FeTiO 3 ) Gangue Minerals: quartz feldspars silicates clays MnO 2 calcite
Iron Ores Ore Types: high grade hematite: Carajas, Brazil (pure mineral) low grade hematite: Shefferville ores, N. Quebec (yellow/red/blue ores) hematite/magnetite: Iron Ore Company of Canada disseminated magnetite: Taconite ores in Minnesota hydrated/weathered ores: Itabirite and Limonitic ores carbonate ores: Siderite ores (Sault St. Marie)
Iron Ores Problems: magnetite recovery: associations with hematite gravity separation: fine size liberation flotation: reverse flotation of gangue Product: SiO 2 content < 2% Quality product size (lump, sinter feed, pellet feed) magnetite content
Iron Ore – Pig Iron Fe 2 O 3 + 3CO → 2Fe + 3CO 2 2 C(s) + O 2 (g) → 2 CO(g) 3 Fe 2 O 3 (s) + CO(g) → 2 Fe 3 O 4 (s) + CO 2 (g) Fe 3 O 4 (s) + CO(g) → 3 FeO(s) + CO 2 (g) CaCO 3 (s) → CaO(s) + CO 2 (g) FeO(s) + CO(g) → Fe(s) + CO 2 (g) C(s) + CO 2 (g) → 2 CO(g) Final Products CaO + SiO 2 → CaSiO 3 Fayalite Slag Pig Iron (95 %Fe; 5%C)
MINE LIFE CYCLE, DOWNSTREAM PROCESSING, AND SUSTAINABILITY STAGE 1 - Exploration and Assessment STAGE 2 - Construction STAGE 3 - Operation STAGE 4 - Closure
MINE LIFE CYCLE, DOWNSTREAM PROCESSING, AND SUSTAINABILITY STAGE 1 - Exploration and Assessment (1-10 years) Exploration - Geophysics Exploration - Drilling (1/10) Geology - Analytical and Mineralogical Assessment Economic Feasibility Assessment (1/10) Orebody Modeling (1/10) Mine Planning and Metallurgical Testwork
Mine Life Cycle (continued) STAGE 2 – Construction (0.5-2 years ) Mine –Shaft-sinking & tunnel/stope development (U/G) –Adit & tunnel/stope development (mountain-top) –Top soil removal, key-cut, haul road (Open-Pit) Plant –Site Preparation, Foundations, Construction of buildings –Procurement and Installation of Equipment Waste and Tailing Disposal –Site Selection and Preparation –Construction of Initial Coffer Dam for tailing disposal
Mine Life Cycle (continued) STAGE 3 - Operations ( 3 - 100+ years ) Mine –Blast, Load, Haul, Dump –Transport (hoist, convey, truck, rail), Stockpile –Safely Store Waste (on site or in-mine) Mill –Crush, Grind (comminution) –Physical Separation (maybe chemical) (beneficiation) –Thicken and Filter (dewater) –Safely Store Tailing
Mine Life Cycle (continued) STAGE 3 - Operations ( 3 - 100+ years ) Waste Disposal –Dump –Contour, Spread top soil –Hydro-seed and plan for final drainage Tailing Disposal –Plan for Lifts as Tailing Dam builds –Control water levels –Recover water for recycle –Revegetate dam walls
Mine Life Cycle (continued) STAGE 4 - Closure( 1 – 20+?? years ) Mine –Flood Pit –Seal Underground workings –Long-term Acid Rock Drainage plan for waste dumps Mill –Salvage Equipment –Raze Buildings –Contour and reseed site –Long-term ARD plan for tailing dam
Sustainability Important Factors –Technical –Economic –Social/Political –Environmental Past mining activities focused on only the first two Last two are now equally, if not more important
Sustainability A Mine must plan for closure before it starts up A mining company must always consider local communities in all parts of the world As an industry, we must find ways to enhance our image and influence government decision-making Future methods must reduce the mining 'footprint' –no more open pits (????) –waste returned to the mine –processing at the face –robotics and remote-mining systems
Sustainability BC Mining Industry must encourage its members to institute vertical integration policies We need to invest in much more value-added processing (i.e. smelting and refining in BC) Downstream manufacturing industries must be encouraged to develop in BC Provide necessary systems to begin significant recycling of metals and other materials in Pacific North-West
Sustainability Social/Political Issues –Land Use –Government policies –The Influence of Activism –Environmental concerns –Aboriginal peoples and treaties –Need for jobs and a diversified economy In BC, the Tatsenshini/Windy Craggy decision has had important long-term impact on Mining Similarly, Delgamuk decision and Nishka Treaty are important to the future of BC's mining industry