Pyrometallurgical processing wastes

Tin slags account for a sizeable fraction of the world s tantalum production. These slags are melted in electric arc furnaces, together with coke and lime (as flux), and this pyrometallurgical process leads to the production of synthetic niobium/tantalum concentrates. The waste products of this operation are mechanically separated slags which can be used, for instance, as landfill. The exhaust gases from this process are of minor consequence if dust is eliminated by the use of filters. 

Copper conversion is accomplished by a pyrometallurgical process known as smelting. During smelting the concentrates are dried and fed into one of several different types of furnaces. There the sulfide minerals are partially oxidized and melted to yield a layer of matte, a mixed copper-iron sulfide, and slag, an upper layer of waste. 

Some years ago, the process, shown in Fig. 14.20, was suggested as a centrally located plant for treatment of metal-containing waste in Sweden. The operation is based on the use of a pyrometallurgical induction converter and hydrometallurgical AmMAR process technology. 

Electrolytic processes can potentially produce lead of greater purity than secondary pyrometallurgical routes, without passing through a conventional smelting and refinery process, and they have fewer waste products. The disadvantage of this type of operation is the high cost of electricity and/or other consumables that are needed to yield a metal that is often priced at below US 500 per tonne. 

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