Minimizing hydrogen cyanide evolution during purification of aqueous waste liquor containing cyanide, e.g. from electroplating, chemical industry, coke oven or ore dressing, involves adding heavy metal compound before oxidation

摘要

Method of minimizing evolution of hydrogen cyanide (HCN) during purification of aqueous waste liquor containing cyanide comprises adding heavy metal compound(s) that react with cyanides to the water to be treated, reaction with the cyanides to cyanide-heavy metal complexes (I) and oxidation as usual. An independent claim is also included for a variant that involves partly leaving the heavy metal hydroxides precipitated during the reaction in the process, reaction with the cyanides to (I) and oxidation as usual.