Zinc concentrate

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Zinc Concentrate is a highly hazarous product used in the production of Zinc Metal and Zinc Alloys, which is the result of a flotation process after the Zinc ore has been mined and milled. The zinc ore contains 1-15% zinc whereas the concentrate typically contains approx. 55% zinc, 6.5% iron and 32% sulphur together with other elements at much lower levels.

By percentage Zinc Concentrate normally contains Zinc Sulphide (80% to 85%), Iron Sulphide (7.0% to 12%), Lead Sulphide (3.0% to 5.0%) Silica (2.5% to 3.5%), and Cadmium Sulphide (0.35% to 0.41%).

The Zinc production process involves roasting the concentrate at approximately 950°C. When the right temperature is reached oxidisation of the zinc, iron and sulphur occurs. The sulphur can be collected and turned into commercial grade Sulphuric Acid (H2SO4).

The iron and zinc then oxidises, and having been reduced to a powdered form is diluted with sulphuric acid, neutralised, and then filtered to remove contaminants.

The refined solution is then electrolysed in a cell fitted with a lead anode and an aluminium cathode. In this process the Zinc is deposited on the cathode from which it is later stripped off. It is then send to a foundry where it takes its final form as either zinc metal (99.95% pure zinc), or zinc alloy together with copper, aluminium or magnesium. The zinc is cast into various forms (normally ingots or plates)with weights from 9 kg to 4 tons.