PROCESS OF REMOVING ARSENIC FROM WASTE SULFURIC ACID

摘要

The present invention relates to a process in which arsenic is removed from waste sulfuric acids by being precipitated as a sulfide by means of a sulfiding agent and arsenic sulfide is separated with the assistance of filter aids. To improve the degree of separation of arsenic in excess of 99%, an H2S atmosphere is maintained during the precipitation and a sulfiding agent is used which consists of an aqueous solution of a mixture of sodium sulfide and sodium hydrogen sulfide. Sodium sulfide is used in an overstoichiometric quantity relative to the arsenic content of the waste sulfuric acid. Waste acids are treated which may contain 10 to 30% free sulfuric acid and 1 to 10 grams arsenic per liter. The suspension is suitably purged to remove hydrogen sulfide before the precipitated arsenic sulfide is filtered.