Presentation on theme: "Sustainability Important Factors"— Presentation transcript:
1 Sustainability Important Factors TechnicalEconomicSocial/PoliticalEnvironmentalPast mining activities focussed on only the first twoThe latter two have now become equally, if notmore important
2 Sustainability A Mine must plan for closure before it starts up A mining company must always consider local communities in all parts of the worldAs an industry, we must find ways to enhance our image and to influence government decision-makingFuture methods must reduce the footprint of miningno more open pitswaste returned to the mineprocessing at the facerobotics and remote-mining systems
3 SustainabilityThe BC Mining Industry must encourage its members to institute vertical integration policiesWe 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 BCThis will provide the necessary systems to begin significant recycling of metals and other materials in the pacific North-West
4 Sustainability Social/Political Issues Land UseGovernment policiesThe Influence of ActivismEnvironmental concernsAboriginal peoples and treatiesNeed for jobs and a diversified economyIn BC, the Tatsenshini/Windy Craggy decision hashad important long-term impact on MiningSimilarly, the Delgamuk decision and Nishka Treaty are important to the future of BC's mining industry
5 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?
6 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.
7 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
8 What is Waste? Waste rock can become ore at some later point in time. - metal/commodity prices can change- other values are discovered within the waste- new technology is developed- cost of environmental protection becomes too high- ore has been exhausted; too costly to close the mine
9 Mineralogy in MMPEThe types of minerals in the ore have major impact on the 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
10 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 products- perform metallurgical testwork on ore samples containing different mineralogyVirtual Atlas of Opaque and Ore Minerals in their Associations <http://www.smenet.org/opaque-ore/>
11 Process Mineralogy- establish the metallurgical performance of each process stage for each ore mineral type- determine in which size ranges, losses are occurring and examine which minerals are responsible for these losses- establish the influence of impurity minerals on product quality- use all of the above information to decide on process changes that will improve plant performance with respect to recovery and product quality
13 Copper OresOre Types:Porphyry: igneous rock of large crystal size (phenocrysts) embedded in a ground mass. Typical mineralization is disseminated chalcopyrite with molybdenite.Massive: pyrite/pyrrhotite host with chalcopyrite, pentlandite, sphalerite, arsenopyrite, galena.Vein-type: quartz host with veins of chalcopyrite, chalcocite and pyrite
14 Copper Ores Problems: Liberation: fine grinding may be required. Recovery: oxide/sufide ratio changes,presence of slime particles,poor recovery of coarse copper minerals.Product: poor liberation, presence of As, Bi, PbQuality high %H2O, variable Cu gradeSeparation: poor distribution of Co, Zn, Pb, etc.
15 Copper OresAnhedral chalcopyrite (yellow, top right) is intergrown 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 Salavdor, Chile
17 Nickel OresOre Types:Massive: pentlandite and chalcopyrite in relatively equal quantities in massive pyrrhotite.Massive: low copper content in pyrrhotite host.Massive: presence of clay slimes,chalcopyrite/pentalandite with pyrrhotite
18 Nickel Ores Problems: Ni-associations: 3 types - as pentlandite - solid-solution in pyrrhotite- "flame" pentlandite in pyrrhotiteLiberation: fine grinding may be requiredfor "flame" pentlandite.Recovery: solid-solution losses.magnetic vs. flotable pyrrhotiteProduct: clay contaminationQuality high %H2O, variable Cu/Ni grade
19 Nickel Ores Problems: Cu-Ni separation: - at milling stage - at the smelting stage- at the matte separation stageSynthetic Minerals: heazlewoodite (Ni3S2)chalcocite (Cu2S)Fe-Ni alloy (PMs)
22 Nickel Ores Chalcopyrite, pyrrhotite, pentlandite, and cubanite - Stillwater, Montana, USANotice flame pentlandite in chalcopyrite
23 Nickel Ores125µmPyrrhotite (brown) has pentlandite (light brown, higherreflectance, centre) exsolution bodies as flames, alignedalong (0001). Minor amounts of chalcopyrite (yellow, centreright) are associated with cleavage and fractures withinpyrrhotite. Silicates are black.
24 Nickel OreRhomb-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 withchalcopyrite (yellow, centre) and encloses magnetite (grey, top left).
26 Lead/Zinc Ores Ore Types: Pb/Zn: galena, sphalerite and pyrite Cu/Pb: chalcopyrite, galena and pyrite.Cu/Zn: chalcopyrite, sphalerite and pyriteCu/Pb/Zn: chalcopyrite, galena, sphalerite and pyrite
27 Lead/Zinc Ores Problems: Zn depression: ZnS is readily activated by Cu ionsCu/Pb separation: essential to avoid Cu smelterpenaltiesLiberation: difficult to assess without mineralogyProduct: Zn conc > 55-58%ZnQuality Pb conc > 60-65%PbCu conc > 25%Cu
28 Copper, Lead, Zinc Ores Euhedral arsenopyrite (white, high reflectance, left) is inter-grown with galena (light blue-white with triangular cleavagepits, centre), chalcopyrite(yellow, centre) and sphalerite(light grey, centre right), withfine chalcopyrite inclusions(top left) or submicroscopicchalcopyrite (grey to brown-grey, centre right). A lath of poorlypolished molybdenite (light grey, centre) is enclosed within chalcopyriteand galena and has partially rimmed arsenopyrite (bottom right).Minor amounts of rutile (light grey) form acicular crystals within thegangue (right centre). Black areas are polishing pits.
29 Copper, Lead, Zinc Ores Reniform sphalerite (light grey, centre) is interbanded with galena(white, centre bottom) and chalco-pyrite (yellow) in successivegrowth rings. Chalcopyrite in thecentre of the right sphalerite hasreplaced poorly crystalline pyrite(white, top right). Chalcopyritecan be seen to have higher relief than galena (bottom left).The gangue (dark grey) is sulphate. Black areas are polishing pits.
31 Iron Ores Ore Types: high grade hematite: Carajas, Brazil low grade hematite: Shefferville ores, N. Quebechematite/magnetite: Iron Ore Company of Canada,Labradorhydrated/weathered ores: itabirite and limonitic orescarbonate ores: Siderite ores (Sault St. Marie)
32 Iron Ores Problems: magnetite recovery: associations with hematite gravity separation: fine size liberationflotation: reverse flotation of gangueProduct: SiO2 content < 2%Quality product size(lump, sinter feed, pellet feed)magnetite content