| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase the exudation rate of arsenic and to improve the exudation ratio by adding a copper compound in a raw material slurry to exude and separate arsenic in a solution. SOLUTION: The raw material slurry is prepared by adding water to the smelting intermediate material containing arsenic and charged in a reactor with the addition of the copper compound such as an electrolytic sediment copper. Next, the reaction is proceeded by blowing air at a proper rate while controlling pH to 6.5-7.5 by adding a NaOH aq. solution and the temp. to 60-90 deg.C. After that, the slurry is filtered to be separated into a copper-containing residue and the solution. Calcium hydroxide is added in the resultant solution to recover calcium arsenate having a stable form. In such a case, the addition of the copper compound is by the following reason. The copper compound reacts with arsenic sulfide to be converted to copper sulfide and arsenic is oxidized into arsenous acid. Since the formation of arsenous acid is accelerated by the reaction, the reaction time is reduced and the exudation ratio is improved.</p> |
