Effect of lime addition during digestion on stability of digested liquor of diasporic bauxite

Abstract

The hydrolysis loss of digested alumina from bauxite reentering into the bauxite residue has always been the research focus during the Bayer process. The stability of sodium aluminate solution after digestion with different lime additions during the dilution process from a diasporic bauxite was studied, and the mechanism by which the lime addition affects was also discusscd. The molar ratio, silica index and hydrolysis degree of diluted liquor after digestion are highly affected by the lime addition, and the corresponding alumina extraction efficiency of bauxite and the Na20 to Si02 ratio of bauxite residue are changed. The stability of diluted liquor is firstly increased by the lime addition below 15% of the bauxite, and then decreased as the lime addition increases. The mineral content and proportion of desilication products precipitating during digestion are the main factors affecting the stability of sodium aluminate solution after digestion.