폐니켈-카드뮴 침출용액으로부터 황화물 침전법을 이용한 카드뮴 회수에 대한 연구

A large amount of waste nickel-cadmium batteries are being produced, and various studies have been conducted to recover the valuable metals contained in the batteries. Solvent extraction is mainly used to recover nickel and cadmium, but that method has economic and environmental problems. In this study, to solve these problems, we investigated the recovery of cadmium by a sulfide precipitation method. The electrode powders obtained from the waste nickel-cadmium battery were leached with sulfuric acid to make a nickel-cadmium mixed solution. Na2S, (NH4)2S and FeS were used as a precipitant and added in a ratio of MeS/Cd = 0.5 - 2. Then, the precipitated powders and filtrate were analyzed to obtain CdS characteristics and cadmium recovery. The cadmium was separated by ion substitution which occurred when the sulfide was added to the nickel-cadmium solution. The recovery of cadmium increased with an increasing sulfide addition. Na2S did not generate any secondary phase, and this study confirmed that 100% of the cadmium in the nickelcadmium solution was recovered. (Received April 30, 2019; Accepted September 16, 2019)