Hydrometallurgical zinc refining

By adopting some characteristics of silica precipitation in sulfuric acid solutions, we were able to achieve the efficient treatment of high silica-bearing zinc concentrate. This process can be applied in practical operations without any major changes in the conventional hydrometallurgical zinc refining process. 

In the most common hydrometallurgical process for zinc manufacturing, the ore is leached with sulfuric acid to extract the lead/zinc. These processes can operate at atmospheric pressure or as pressure leach circuits. Lead/zinc is recovered from solution by electrowinning, a process similar to electrolytic refining. The process most commonly used for low-grade deposits is heap leaching. Imperial smelting is also used for zinc ores. 

Unfortunately, the copper product requires extensive refining before being marketable. Moreover, scrap iron cannot displace zinc, cadmium, or many other trace contaminants from solution. Zinc is more versatile than scrap iron, having a lower reduction potential. However, although zinc is used extensively in hydrometallurgical processes to cement copper, nickel, and cobalt from zinc leach solutions before electrolysis " and to recover gold and silver in the Merrill-Crowe process. the Zn + ions introduced into solution would be unacceptable for environmental applications, even if the process were economically attractive. 

---