Utilization of high-gradient magnetic separation–secondary grinding–leaching to improve the copper recovery from refractory copper oxide ores

Abstract Copper-oxide raw ore has a complex composition and cannot be processed effectively by conventional, single-stage sorting methods. Based on the characteristics of copper-oxide ore, a new combined grinding–flotation–high-gradient magnetic separation–secondary grinding–leaching process has been proposed to recover copper. Test results show that the new process is very effective. Sodium sulfide was used as a vulcanizing agent in the flotation process, and butyl xanthate was used as a collector to obtain a qualified copper concentrate with a copper grade of 29.37% and a recovery rate of 32.22%. The flotation tailings were subjected to high-gradient magnetic separation to obtain magnetic concentrates and magnetic tailings, and copper was recovered by leaching from the magnetic concentrates and tailings. After secondary grinding of the magnetic concentrates, the leaching rates of copper from the magnetic concentrates and magnetic tailings were 26.85% and 26.95%, respectively. The total copper recovery was 86.02%. The new process introduces high-gradient magnetic separation, enriches refractory chrysocolla, leaches chrysocolla at 65 °C, leaches malachite from the magnetic tailings at 40 °C, and saves heating costs. Secondary grinding can reduce the leaching temperature, shorten the leaching time, and achieve a low energy consumption and effective extraction of refractory copper-oxide ore.