METHOD OF PROCESSING HYDROLYSED SODIUM ARSENITE INTO COMMERCIAL PRODUCT Russian patent published in 2014 - IPC C01G28/00 

FIELD: chemistry.

SUBSTANCE: method of processing hydrolysed technical sodium arsenite into a commercial product involves cyclic repetition of consecutive steps. First, arsenic salts are leached from material with hydrochloric acid solution, which is added until achieving pH 9.5-10.5, to form a heterogeneous system. The heterogeneous system is then divided into a solid phase and a working solution. Further, the working solution is concentrated through evaporation to arsenic (III) content greater than 10 g/100 g water and the concentrated working solution is separated from the formed precipitate. Arsenic (III) oxide is precipitated by acidifying the working solution and the arsenic (III) oxide precipitate is filtered off. The filtrate is returned to the first step of the process. After repeating the cycle of said operations 3 to 10 times, arsenic (IV) compounds are then extracted from the working solution via reduction thereof to arsenic (III) compounds or to elementary arsenic.

EFFECT: invention reduces the amount of process wastes and improves safety when processing hydrolysed sodium arsenite.

2 cl, 2 ex