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Download STAGES IN MINERAL PROCESSING
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STAGES IN MINERAL PROCESSING LIBERATION: separating minerals into individual grains. Primary liberation is carried out by crushing. This is done in a jaw crusher at the mine. The grains are further liberated at a plant which is often on the mine site. Secondary liberation takes place at the crushing plant. The grains are passed through a cone crusher, a rod mill and finally a ball mill. At each stage the grains are screened and any liberated grains are removed. SEPARATION: The metallic minerals are separated from the gangue (waste). Methods of separation: Method Suitable for: PHYSICAL Gravity separation (e.g. on shaking tables) X-ray separation Magnetic separation Electrical conductivity CHEMICAL Froth flotation – chemicals make mineral grains water repellent, so grains float to the surface of a pool. Chemicals used depend on the nature of the mineral. Concentrated ore is then removed from the site for SMELTING: metal is heated to remove impurities such as sulphur. An ore melt forms as well as a layer of slag. Other chemicals may be added to remove impurities, e.g. silica is added to remove iron from copper melts, whilst limestone removes impurities from iron. An example is the extraction of copper from Mt Isa in Australia. Read t he information about the mine, study the diagram and draw a flow diagram to show the stages in copper extraction.
