Investigation of effect of colemanite addition on copper losses in matte smelting slag

In this study, the aim was to reduce copper losses to slag in copper production by using a boron compound, called colemanite (2CaO.3B ₂O ₃.5H ₂O), as flux, besides silica. In order to achieve this purpose, two different matte-slag couples were used; the flash furnace matte-slag obtained from Eti Copper Inc. (EBI?) and a master matte-slag without copper produced synthetically under laboratory conditions. Chemical analyses of flash furnace slag and synthetic master slag were 0?88%Cu- 36?1%SiO ₂-43?9%FeO-3?7%Fe ₂O ₃ and 37?6%SiO ₂-60?0%FeO-2?4%Fe ₂O ₃ respectively. In each experiment, the same amounts of slag and matte were mixed with the addition of predefined amounts of colemanite and melted together at 1250°C for different durations under nitrogen atmosphere in a silica crucible. Results showed that it was possible to decrease the copper losses to about 0?3-0?4% by accelerating the settling rate of matte particles by the addition of colemanite, which was attained by the expected increase in flash furnace slag fluidity and lowering of its liquidus temperature.