Process for the separation of arsenic acid from a sulfuric acid-containing solution

A process for reducing arsenic levels in a solution comprising sulfuric acid, water, and arsenic acid comprising the steps of:

• (a) reacting the solution with copper or a copper-containing compound in an amount sufficient and at a temperature sufficient to produce a solution containing dissolved copper arsenate;
• (b) adding alkali solution to said solution resulting from step (a) in an amount sufficient to neutralize said sulfuric acid and said arsenic acid and to precipitate said dissolved copper arsenate;
• (c) separating said precipitated copper arsenate from said solution resulting from step (b);
• (d) treating said solution resulting from step (c) with a soluble ferric-containing compound in an amount sufficient to convert the arsenate salt of the alkali to ferric arsenate wherein the amount of said soluble ferric-containing compound added is in the ratio of iron to arsenic of about 8:1 to about 10:1 and adding alkali to said solution in an amount sufficient so that the pH of said solution is about 5 to about 7;
• and
• (e) separating ferric arsenate formed from said solution resulting from step (d) to form a solution containing less than about 0.79 parts per million arsenic.