Recovery of iron from copper flash smelting slags

Abstract

Copper slag is produced in large amounts in seven copper smelter plants in Chile, and it is estimated that around four million tons of slag are disposed every year, and another 40–45 million tons are historically cumulated. Copper slag contains iron in the range of 42–45%, which can be recovered and recycled along with the contained copper to obtain an iron–copper alloy and a final slag rich in oxides. Therefore, the present work shows the experimental results of the reduction of a flash smelting slag using coke as reductant up to 150% of the stoichiometric carbon required to reduce copper oxide and magnetite. The characterisation and thermodynamic stability of compounds contained in the slag are presented, and the obtained results show the feasibility for recovering an iron rich alloy with iron contents higher than 98% and copper in the range of 0·6–0·8% using a two‐step process.