Page 29 - Curriculum Visions Dynamic Book

Refining copper
Copper occurs as both oxide ores and sulphide ores. The easiest to refine are the oxides. In an industrial furnace the carbon monoxide gas needed to reduce the ore (remove the oxygen from the metal) is produced by heating coke, a source of carbon, and feeding in
a jet of air. The carbon reacts with oxygen from the air to form carbon monoxide, which then reduces the copper oxide to copper. The copper can then be tapped from the base of the furnace.
This is similar to the iron blast furnace shown on pages 26–27.
Copper ores containing sulphur are very much more difficult to deal with, yet they make up half of all copper deposits. These ores have to be oxidised, as shown by the equation on this page. When they are burnt, huge quantities of polluting sulphur dioxide gas
are produced. This gas is one of the major causes of acid rain, and modern factories recover as much as they can in the production of sulphuric acid.
electrolysis: an electrical– chemical process that uses an electric current to cause the break up of a compound and
the movement of metal ions in a solution. The process happens in many natural situations (as for example in rusting) and is also commonly used in industry for purifying (refining) metals or for plating metal objects with a fine, even metal coating.
sulphide: a sulphur compound that contains no oxygen.
 A furnace of copper being unloaded after smelting.
EQUATION: Oxidation of copper sulphide ore in a smelter to produce copper
Copper sulphide + limited air supply ➪ copper + sulphur dioxide 2CuS(s) + 2O2(g) ➪ 2Cu(l) + 2SO2(g)
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