Improvement of the technological scheme for processing zinc concentrates by hydrometallurgical method at JSC Almalyk MMC

Abstract

The extraction of zinc from concentrates is carried out in pyrometallurgical and hydrometallurgical ways. Obtaining pure zinc of the highest grades is possible using the hydrometallurgical method, in which the calcined sulfide concentrate is subjected to sulfuric acid leaching, a solution of zinc sulfate and a recycled product is formed - a solid residue of the cake leaching process. After purification, the zinc sulfate solution is subjected to electrolytic refining, and the cake is processed pyroly or hydrometallurgically. At JSC "Almalyk MMC" in the process of hydrometallurgical processing of zinc concentrates, the resulting zinc cake is processed by the pyrometallurgical method - rolling. The rolling process takes place in two tubular furnaces (rolling furnaces) 50 meters long and 3.5 meters in diameter at a temperature of 1100–12000C, in the presence of a reducing agent, coke breeze and petroleum coke. As a result of the rolling process of zinc cakes, sublimates and a solid technogenic residue, clinker, containing copper, gold, and silver are formed. Clinker is processed at the plant in smelting furnaces to extract precious metals, but it is accumulating more than 450 thousand tons. In connection with this, scientific research is currently underway on the processing of zinc cakes using a hydrometallurgical method to eliminate the expensive rolling process of processing zinc cakes; high-temperature (900 C) sulfuric acid leaching of cakes with a size of 0.074 mm has been developed during leaching for 4-4.5 hours, the extraction of zinc into the solution is 98.5%; copper 92.8%; iron 75.2; cadmium 79.2.