Study on Fluorine Chlorine Removal from Zinc Oxide Fume of Multiple-hearth Burner by Alkali Cleaning

In the hydro-zinc smelting system, a large amount of fluorine and chlorine ions not only hinder the smooth progress of the electrolysis process, but also accelerate the corrosion of the equipment. In this paper, the alkaline washing process is used to remove fluorine and chlorine from the high fluorine and chlorine zinc oxide soot from a multi-hearth furnace. Effect of sodium carbonate concentration, alkaline washing temperature, alkaline washing time, liquid-solid ratio, and sodium hydroxide concentration on the removal rate of fluorine and chlorine is studied, adding the influence of zinc loss rate. The results show that under the conditions of a sodium carbonate concentration of 150 g/L, an alkaline washing time of 2 h, a reaction temperature of 80℃, a slurry-to-solid ratio of 5∶1, and a sodium hydroxide concentration of 40 g/L, the composite lye will affect the multi-hearth furnace.The removal rate of zinc oxide, fluorine and chlorine is the best, 85.01% and 93.57% respectively, and the loss rate of zinc is 2.67%.