METHOD OF PRODUCING ARSENIOUS ACID

摘要

PROBLEM TO BE SOLVED: To provide a method of producing, from a solution containing arsenic acid and arsenious acid, an arsenious acid which has little deposits of impurities and high quality and which has a large diameter and god handling property when packaged or filled. SOLUTION: In the method of producing arsenious acid, the total concentration of pentavalent and trivalent arsenics is controlled to 40-50 g/l when the arsenic acid in the solution containing the arsenic acid and arsenious acid is reduced by sulfurous acid gas. The arsenic acid recovered by deposition through reduction of the arsenics has a large particle diameter and a high-purity arsenious acid can be obtained by removing impurities therefrom through washing.