PURPOSE: To effectively recover high purity Ni and Co, bycontacting the liquid containing Ni and Co and organic solvent containing a specific organic phosphor compound as extracting agent.
CONSTITUTION: Water solution containing Ni and Co, removed impurities previously, is contacted with organic solvent using 2-ethylhexy.phosphoric acid mono-2- ethylhexyl ester, shown in the formula, as extracting agent, added the diluent, such as kerosine etc., and Co is extracted in the solvent selectively. On this occasion, extraction is carried out at about 60°C, controlling pH at 5.5W7 and volume ratio of each phase of organic solvent and water at about 1. As a result of it, extracting efficiency is made maximum. Next, washing of impurities is carried out at 60°C, 4W5 of pH and within the limits of 0.5W2 of volume ratio of solvent layer and water phase and pH of extracting phase is made less than 1.5 by mineral acid etc. Thus, Co is extracted reversely at nearly 100% and high purity Co and Ni are able to recover.
NAMIHISA SHIYOUICHIROU
FUJII TSUMORU
