The settling behavior of matte particles in copper slag and the new technology of copper slag cleaning

Abstract

Settling time, system temperature and reductant amount play an important role in the recovery of matte from copper slag. This study investigated the settling behavior of matte particles in copper slag and the effects of the settling time, system temperature, and reductant amount on the macrostructure of slag, microstructure of matte particles, and copper loss. The results showed that the settling behavior of matte particles in slag at the experimental temperature was a process of aggregation and growth. With an increase in settling time and temperature, as well as the addition of an appropriate amount of anthracite, the foaming slag layer of the slowly cooled slag gradually disappeared, while the recovery of matte increased. However, when the amount of anthracite was too high, Fe–Cu alloy formed at the experimental temperature, which resulted in worsened fluidity of the matte in the molten slag and copper loss increased. At the experimental temperature, the settling environment of matte particles in the liquid phase layer was superior to that of the foaming slag layer. The novel idea of using rubber seed oil instead of a traditional fossil reductant to clean the copper slag was put forward. At the temperature of 1250 °C, 4 mL of rubber seed oil was injected, resulting in a settling time of ≥90 min, after which the copper content in the upper part of the slowly cooled slag was less than 0.57 wt.%, reaching the acceptable level of discardable slag in industry.