Abstract: To accomplish the comprehensive utilization of boron mud， the desilication of boron mud was studied using molten sodium hydroxide media. The effect on silicon dioxide extraction ratio caused by the factors， such as reaction time， reaction temperature and mass ratio of sodium hydroxide to boron mud， was analyzed. The optimum reaction condition of desilication was obtained through the orthogonal tests. The results showed that the extraction ratio of silicon dioxide reaches 91.9% and MgO content reaches 92.04% in the solid residuals under the optimum reaction conditions of desilication. The reaction time is 20min， the reaction temperature is 550℃ and the mass ratio of sodium hydroxide to boron mud is 1.75∶1. The solid residuals were characterized by XRD and SEM.

Key words: boron mud, sodium hydroxide, desilicication, magnesium oxide, orthogonal test