Presentation on theme: "Topic 1: Types of ore Bodies and Mine Processes"— Presentation transcript:
1 Topic 1: Types of ore Bodies and Mine Processes ExtractionOpen PitStrip MiningUndergroundCrushingInitialAutogenous CircuitBeneficiationPhysicalChemicalElectrochemicalSmelting
2 Types of Ore Massive: base metal Cu, Ni, Zn Disseminated: gold, INCO Thompson Ni oreMassive: base metal Cu, Ni, ZnDisseminated: gold,DiamondsSnow Lake0.16 oz Au / tonneEkati, NWT, DiamondsBissett Au
3 Bedded Ore bodies Potash, Saskatchewan Syncrude, Oil sands, Fort McMurrayBlack Thunder Coal Mine Wyoming, USA
4 Extraction process depend on shape, position and value of ore body Open PitStrip MiningUnderground MineDissolution: potash, uranium,In situ mobilization: oil shaleHeap LeachWhat are the major environmental issues related to each form of extraction?
5 Open Pit Bingham Canyon Cu Mine Ekati Diamond Mine Note: The amount of waste rock to be removed to provide reasonable gradient for trucks.Only efficient for large ore bodies close to the surfaceCan be useful for dumping mine waste at closure
6 Strip Mining Very efficient for high level flat lying ore bodies. Overburden and top soil can be replaced minimizing environmental damage
10 CrushingOre bearing and non ore-bearing rock will be separated as soon as possibleWhat happens to non-ore-bearing rock?Ore-bearing rock will be crushed to the size necessary to liberate the required mineralHeap leach requires only very coarse crushingMuch finer crushing for gold and PGE as theyare enclosed within other mineral grainsInitial crushing undergroundIn mill, crushing in autogenous circuit withfeedback of large particlesFinal crushing in rod or ball mills
11 Beneficiation (Extraction of metal from rock/mineral) Physical techniquesGravityGold from quartzDiamondsTantalumFlotationSulphides from silicatesCu and Ni sulphidesNaCl from KClChemical TechniquesCN leachingRoaster oxidizes sulphide to SO2SmeltingElectrochemical Refining of pure metalConsider the waste generated at each stage
12 Gravity SeparationWhiffle tableSeparatorFine grained waste goes to tailings pond. What does it contain?
13 Flotation CellsOre becomes attached to air bubbles, float, and are collected.Gangue sinks to the bottom of the flotation cells and piped to tailings pondChemicals added include:Frothers: pine oils & alcohols promote the formation and stability of bubbles.Collectors promote adherence of air bubbles to the mineral.Conditioners: make the surface of the mineral particle either more or less susceptible to concentration.Activators e.g. copper sulfate, lead nitrate, lead acetateDepressants e.g. sodium cyanide, zinc sulfate
14 Chemical Separation Cyanide leaching for gold at pH 11gold retrieved by Merrill Crowe (precipitation on zinc dust) or Carbon in Pulp (CIP) processRoaster oxidizes sulphide to SO2Releases metal for refining and SO2 to the atmosphere unless scrubbers are in place
15 Smelting Separates remaining silicates from metals Slag (molten silicates) pored offMetal pores into bars or sent for final electochemical refining