METHOD FOR RECOVERING PD ION FROM WASTE LIQUID OF PICKLING OF STAINLESS STEEL WITH PALLADIUM SALT AND NITRIC ACID

PURPOSE:To efficiently separate and recover Pd by specifying the concn. of the excess hydrochloric acid in a waste liquid of pickling with an acid mixture composed of Pd-contg. hydrochloric acid and nitric acid to the specific value or below, absorbing the Pd ion to a ion exchange resin layer and eluting the Pd ion with the hydrochloric acid of a specific concn. etc. CONSTITUTION:The waste liquid of the pickling with the acid mixture composed of the Pd-contg. hydrochloric acid and nitric acid used for descaling of stainless steels is filtered to remove impurities therefrom; thereafter, the liquid is concd. and is diluted with water, by that, the concn. of the excess hydrochloric acid in the waste liquid is adjusted to 1mol/kg or lower. The waste liquid is then passed through the ion exchange resin layer, to which the greater part of the Pd is adsorbed. This Pd is eluted with a 10 to 36wt.% hydrochloric acid solution or an ammonia water contg. 0.1 to 5N ammonia and is then washed with pure water. As a result, the Pd is effectively separated and recovered from the waste liquid of the pickling with the acid mixture composed of the Pd-contg. hydrochloric acid and nitric acid.