Presentation on theme: "Sustainability Important Factors –Technical –Economic –Social/Political –Environmental Past mining activities focussed on only the first two The latter."— Presentation transcript:
Sustainability Important Factors –Technical –Economic –Social/Political –Environmental Past mining activities focussed on only the first two The latter two have now become 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 to influence government decision-making Future methods must reduce the footprint of mining –no more open pits –waste returned to the mine –processing at the face –robotics and remote-mining systems
Sustainability The 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 This will provide the necessary systems to begin significant recycling of metals and other materials in the 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, the Delgamuk decision and Nishka Treaty are important to the future of BC's mining industry
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?
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 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
Mineralogy in MMPE The 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
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 mineralogy Virtual Atlas of Opaque and Ore Minerals in their Associations
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
Copper Ores Ore 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
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, Pb Qualityhigh %H 2 O, variable Cu grade Separation: poor distribution of Co, Zn, Pb, etc.
Copper Ores Anhedral 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
Nickel Ores Ore 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
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 Qualityhigh %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 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 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: Zn depression: ZnS is readily activated by Cu ions Cu/Pb separation: essential to avoid Cu smelter penalties Liberation:difficult to assess without mineralogy Product:Zn conc > 55-58%Zn QualityPb 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 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 sulphate. Black areas are polishing pits.
Iron Ores Ore Types: high grade hematite:Carajas, Brazil low grade hematite:Shefferville ores, N. Quebec hematite/magnetite: Iron Ore Company of Canada, Labrador 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% Qualityproduct size (lump, sinter feed, pellet feed) magnetite content
Samarco Iron Ore Flowsheet
Samarco Iron Ore Concentrator
Samarco Iron Ore Pipeline
Iron Ore Pellets Malmberget, Norway
Gold Ores Minerals:native gold, electrum, tellurides associated with pyrite and/or other sufides Waste:quartz pyrite arsenopyrite feldspars calcite other rock-type minerals
Downstream Processing Gold processing options
Grinding and Cyanide Leaching Musslewhite Mine, Ontario