Effects of Some Additives on Copper Losses to Matte Smelting Slag

Copper is lost to slag between 0.7 and 2.3 wt.% during the industrial copper matte smelting stage. In the present study, the aim was to minimize these losses in the slag phase by adding some fluxing agents like CaO, B₂O₃ and calcium borate (namely colemanite—2CaO·3B₂O₃·5H₂O). Eti Copper Inc. (EBI) flash furnace smelter slag containing 0.88 wt.%Cu and matte with the addition each of CaO, B₂O₃ and colemanite up to 10 wt.% of the total charge were melted in a silica crucible placed in a vertical tube furnace at 1250°C under nitrogen atmosphere for 2 h. The experimental results of matte–slag–flux mixtures showed that the addition of all additives up to 4 wt.% led to a gradual decrease of the copper content in the final slags. Beyond this value, the copper losses to slag increased markedly with the increasing CaO and B₂O₃ additions. On the other hand, the colemanite addition of more than 4 wt.% did not substantially affect the copper losses to slag.