Materials


	Tin Ore - Cassiterite. The ore is crushed washed and roasted before being smelted in a blast furnace or a reverbetory furnace. The tin is then poured into slabs. Refined by electrolysis and because melting is affected by impurities the temperature is controlled. Zinc Ore - zinc blonde. The ore is crushed and then concentrated by floatation before smelting takes place in a blast furnace. The zinc is removed as a vapour condensed when it is in contact with molten lead. Pure forms are obtained by electrolysis.


	Because the major part of aluminium separation is a chemical process it is about 5 times more expensive to produce than steel.


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