In China, for zinc extraction plants, there are generally have two processes: pyrogenic process and wet process. According to material origin, here also has following difference. Normally, for the metal scrap which contains higher zinc, it mainly adopts following methods: reduction distillation, wet process, liquation smelting, aluminum process etc... But for the lower Zinc content raw material, such as, the dust from rotary kiln, the first step normally is to produce zinc oxide (ZnO), then can directly get zinc ingot.
Distillation method and wet process are most popular for zinc slag and ash. Distillation contains two types: horizontal retort type and vacuum type. They has features of lower investment, simple devices and easy operation.
The wet process can be divided into two processes: one is using soluble anode electrolysis; another is process of “leaching - purification - electrodeposition". Both processes use the sulfuric acid and zinc sulfate solution as the electrolyte. In the zinc smelting industry, wet smelting is the main direction, because of higher zinc recovery rate. Additionally, the final mud can be processes by automatic filter press, so it also has less environmental pollution.