The impact of hydrometallurgy on the copper industry
The impact of hydrometallurgy on the copper industry (1) It can process low-grade copper ores. The grade of copper ore treated by heap leaching in the United States is even as low as 0.04%. In the past, off-balance sheet ores, waste rock, tailings, etc. that were considered unprocessable can be reused as copper resources, thus greatly expanding the scope of copper resource utilization; (2) Hydrometallurgy has a simple process and low energy consumption, so the production cost is low. In 1997, the average production cost of Western SX-EW copper was 43 cents/pound, which included 8 cents/pound mining fee, 15 cents/pound leaching fee, 18 cents/pound SX-EW fee, and 2 cents/pound management fee. In 1997, the average production cost of Western pyrometallurgical copper was 70 cents/pound; (3) The investment cost is low and the construction period is short. The unit investment cost of large-scale hydrometallurgical copper smelting plants abroad is 2,300 $/t Cu, while the unit investment cost of pyrometallurgical copper smelting plants exceeds 4,500 $/t Cu. Due to the simple equipment, the unit investment cost of China's hydrometallurgical copper smelting plants is only 10,000 to 12,000 yuan/t; (4) No environmental pollution problem. The hydrometallurgical copper smelting process does not emit SO2 flue gas. When the sulfide ore is pressurized and leached, sulfur can be produced in the form of S2, avoiding the problem of excess sulfuric acid. In particular, underground leaching technology does not require the ore to be mined, does not damage vegetation and ecology, and fundamentally improves the working conditions of miners; (5) The cathode copper product is of high quality. Since the solvent extraction technology has good selectivity for copper, the purity of the copper electrolyte is very high, and the quality of the cathode copper produced can reach 99.999%. In addition, the use of Pb-Ca-Sn alloy anodes and the addition of Co2+ in the electrolyte effectively prevent the corrosion of the lead anode and ensure the quality of the cathode product; (6) The production scale can be large or small, which is particularly suitable for the characteristics of Chinese enterprises. It is precisely because of these significant advantages of hydrometallurgy that it has been able to develop rapidly. When the Asian financial crisis caused a sharp decline in non-ferrous metal prices from the second half of 1997 to 1998, copper prices continued to fall. Some Western copper companies closed their high-cost pyrometallurgical copper smelters, but during this period, the world's hydrometallurgical copper production still grew strongly, which can illustrate the vitality of hydrometallurgy technology. In the past, it was believed that the leaching-extraction-electrowinning process was only suitable for treating waste rock, oxidized ore, and low-grade ore, that is, only suitable for treating ores that are difficult or uneconomical to treat by pyrometallurgy. However, in recent years, the development and industrialization of biotechnology and pressure leaching technology have changed people's understanding. The use of bio-heap leaching can completely treat high-grade secondary sulfide ores, and has reached a large production scale, becoming a very mature production method. The use of pressure leaching technology to treat high-grade secondary sulfide ores has also been industrialized, and has reached a production scale of 50,000 t/aA-grade copper, with an operating cost of only 35 cents/pound. It can be seen that in recent years, the main focus of hydrometallurgical copper smelting has shifted from oxidized ore and waste rock to sulfide ore, and even copper concentrate with chalcopyrite as the main component has been taken as a challenging target. It is believed that in the near future, people will be able to use hydrometallurgical technology to treat any copper ore, and can compete with pyrometallurgy in terms of investment and cost.
