Model for treatment of copper slag produced during copper alloying

Abstract

The purpose of this research is to develop a model for treatment of copper slag produced during copper alloying. Two copper slags were used, one from melting very pure metal to produce silicon brass (slag 1) and the other from remelting scrap to produce brass (slag 2). The model involves crushing, sizing and grinding followed by sieving and leaching. The leaching process was carried out on the size fraction <0·074 mm produced by crushing and grinding using sulphuric acid. Leaching parameters such as acid concentration and time of leaching were investigated. Results obtained for both slags 1 and 2 showed that the coarse fraction from −4 to 0·075 mm was enriched with copper and the size fraction <0·075 mm was enriched with silica. The coarse fraction is 68 wt-% slag 1 containing a copper content of 82 wt-% and a SiO₂ content of 13 wt-% and a copper recovery of 93 wt-%. In the case of slag 2 the coarse fraction was 40% by weight containing at 80 wt-%Cu and 4·7 wt-%SiO₂ with a copper recovery of 80%. Both the coarse fractions from slags 1 and 2 could be recycled either in an alloying process or used for production of copper. The results from leaching size fraction <0·075 mm which represented 32 wt-% of slag 1 and 60 wt-% of slag 2 showed extraction rates of copper of 95 and 97% respectively.