Roast copper

Roasting. Copper and lead sulfides are direcdy smelted but not zinc sulfide. However, theoretical calculations are encouraging (20) and, if an efficient means of condensing zinc rapidly from 1600 K in the presence of carbon dioxide, sulfur dioxide, and steam can be devised, the process may be feasible. The reaction of zinc vapor to yield zinc oxide or zinc sulfide presents the main difficulty. 

Similarly, smelting copper oxide, often derived from roasted copper sulfide ores, proceeds as follows ... 

Copper is extracted in the final stage by roasting copper(i) sulfide (Cu2S) in a current of air. This converts the sulfide to the metal. 

In the patio process the finely ground ore is mixed in a patio or paved courtyard with mercury, common salt, and a mixture of copper and iron sulphates called magistral, prepared by roasting copper pyrites. The ore-heap or torta is kept moist. The reactions involved are obscure and complex, but it is supposed 1 that some of them can be represented thus ... 

At the final stage the prescribed quantities of 55 herbs previously prepared by various processes, along with the prescribed quantity of squill and viper flesh powder (48 drachms), were added to hedychium, long pepper and poppy juice (all at 24 drachms) eight herbs including cinnamon and opobalsam (all at 12 drachms) 18 herbs including myrrh, black and white pepper and turpentine resin (at 6 drachms) 22 others and then Lemnian earth and roasted copper (at 4 drachms each) bitumen and castoreum (the secretion of beaver) 150 drachms of honey and 80 drachms of vetch meal. 

Electrolysis is another important purification technique. The copper metal obtained by roasting copper sulfide usually contains impurities such as zinc, iron, silver, and gold. The more electropositive metals are removed by an electrolysis process in which the impure copper acts as the anode and pure copper acts as the cathode in a sulfuric acid solution containing Cu ions (Figure 20.6). The reactions are... 

Roasted copper ore containing the copper as CuSO is to be extracted in a countercurrent stage extractor. Each hour a charge consisting of 10 tons of gangue,... 

Theys, L.F. and Lee, L.V. (1958) Sulphate Roasting Copper-Cobalt Sulphide Concentrates Journal of Metals 134-136. 

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