Wet method for preparation of sodium arsenate from fume containing arsenic

The present invention relates to a preparation method of sodium arsenate. It uses a tin-roasted dust as raw material, and mixes that with water to make pulp, and then adds an alkali liquor and an oxidant in the above-mentioned pulp. The above-mentioned mixed material is stirred at 50-75 deg.C, and then extracted filtered to remove residue, and then in the obtained filtrate NaOH is added, and the pH value of said solution is regulated to 12-14, said solution is boiled, filtered to remove sediment to obtain its purified liquor, further the purified liquor is concentrated and crystalized, so that the invented sodium aresenate can be made up. Said invention can implement the one-time arsenic extraction and oxydization processes, and can directly prepare sodium arsenate from arsenic contained dust by using full-wet method.