Reduction of copper smelting slag using waste cooking oil

Abstract

Currently, waste cooking oil (WCO) as a renewable energy is not widely utilized. Copper slag cleaning in an electric furnace is a critical process for reducing the excessive magnetite (Fe 3 O 4 ) present in the copper slag to decrease the slag viscosity, which can promote the sedimentation of matte/copper in the slag, thus reducing the copper content of slag. In this study, laboratory-scale experiments were performed for copper slag cleaning using WCO as a reductant instead of traditional fossil fuel-based reductants. The results showed that the Fe 3 O 4 content of the copper slag significantly decreased from 17.8% to 4.2% with the addition of 2 mL of WCO at 1250 °C. To better understand the reduction process, the cracking characteristics of WCO over corundum and Fe 3 O 4 were investigated at 600–1300 °C. The cracking of 1 mL of WCO over corundum and Fe 3 O 4 at 1300 °C yielded 1450 and 1770 mL of gases (H 2 , CO, CO 2 , and methane (CH 4 )), respectively. Combined with thermodynamic analysis, it was found that all the cracking products participated in the reaction of copper slag cleaning. This work offers a novel approach for the clean utilization of WCO for copper slag cleaning. • Waste cooking oil is used as reductant for copper slag cleaning. • A system has been improved to quantitative analysis gas yield. • High temperature cracking characteristics of WCO is investigated in detail.