Study on causticizing process of sewage discharged from wet reclamation of waste sodium silicate sand

Abstract

Wet reclamation of waste sodium silicate sand produces a large amount of alkaline sewage and causes secondary pollution. At present, the neutralization method is commonly used to treat the sewage discharged from the wet reclamation. However, treated sewage contains a large amount of soluble salts, and still causes environmental problems directly discharged. The main solutes in the sewage discharged from the wet reclamation are sodium carbonate and sodium bicarbonate, so the sewage can be converted into lye by a causticizing process and be recycled. In this paper, the causticizing process of the sewage discharged from the wet reclamation was studied, and the effects of causticizing temperature, causticizing time, quicklime consumption, and sewage concentration on causticization rate were investigated. The results showed that it was feasible to treat the sewage discharged from the wet reclamation through the causticizing process, and the causticization rate could be above 92%. Increasing the causticizing temperature, prolonging the causticizing time, improving the quicklime consumption, and reducing the sewage concentration could improve the causticization rate.