Abstract
The recovery of cobalt from the copper smelter slag by sulfurization and flotation was investigated. The copper smelter slag was characterized using XRF, XRD and SEM analysis. The slag was reduced using coke and sulfurized using gypsum. The coke was characterized to know the volatile matter, moisture content, ash content and the percentage fixed carbon. A determined amount of copper smelter slag, gypsum and coke were blended together and were investigated for the sulfurization process. The gypsum contained 97.3% CaSO 4. The sulfurization experiments were carried out at 950 °C using a tube furnace. The products of the sulfurization experiments were characterized by XRD and XRF analysis and floated using a micro-flotation. The products of the flotation experiments were characterized using XRF. It was found that the raw copper slag contained 2.30% Co, 5.27% Cu and 35.13% Fe. After flotation, a concentrate containing 0.88% Co was produced. The highest recovery of cobalt was obtained at pH 8 with a recovery of 38.37%. Sulfurization and flotation of copper smelter slag has potential in valorisation of slag and help to mitigate the release of hazardous heavy metals into the environment.