Wastes as resources: Update on recovery of valuable metals from copper slags

Copper production from sulphide minerals generates massive amounts of slag as final waste of the pyrometallurgical processes. Dumping the slag nearby the smelter plant has been the common practice and, currently it is produced in a proportion of 2.2 ton of slag per ton of blister copper and is granulated to facilitate the transportation and final disposal. Thus, it is relevant to improve sustainability by recycling this waste to minimise the environmental impact generated during pyrometallurgical treatment of copper sulphides concentrates. Laboratory tests were run in order to concentrate and separate metals and materials for obtaining results that could be scaled up to pilot and industrial level. The results of pyrometallurgical and hydrometallurgical experiments are presented in order to show the importance of the oxidation of the slag at high temperatures that could liberate those metals molecularly entrapped during processing sulphide concentrate in the smelter plant. Therefore, the present work shows experimental work done in Chile in order to add value to this waste by recovering contained metals and materials such as copper, molybdenum, and iron and silica, with iron and silica being more than half of the total content of the slag, which has an important effect on the volume of the stocked material.