Abstract: Copper slag has a huge output and a high content of valuable components.Its recycling has considerable economic benefits and environmental protection significance.Aiming at a mixed copper slag,the study on the slow cooling and optimization of grinding and flotation of copper slag was carried out.First,the slow cooling of the copper slag was controlled to regulate the crystal size and growth,that is natural cooling for 24 hours,spray cooling for 24 hours and natural cooling for 24 hours.Then,the process flow of stage grinding and stage separating was adopted,and a instant flotation was set up in the grinding circuit,which not only helped obtain the highquality copper concentrate with a yield of 10.04%,copper grade of 21.02% and recovery rate of 60.24% in advance,but also reduced the amount of ore entering the subsequent grinding and flotation process,thus greatly decreasing the regrind cost and the cost of reagents.Finally,the tailings of instant flotation reported to regrinding,followed by being subject to onestage roughing,twostage cleaning,and twostage scavenging to reduce the copper grade in tailings to 0.29%.The proposed copper slag processing flow is short and efficient.The overall copper concentrate grade of the whole process is 20.70%,and the recovery rate is 93.02%,reaching China’s advanced level.Meanwhile,the tailings can be directly sold as additives for cement plants,and the beneficiation water can be directly reused,basically achieving zero discharge of production solid waste and wastewater,which provides a good reference for the comprehensive recovery and utilization of similar smelting slag,and is of great significance to the sustainable development of China's copper industry.

Key words: copper smelting slag, cooling method, instant flotation, stage grinding, stage separating