Purifying nickel sulphate

摘要

The method of purifying nickel sulphate comprises a first purifying step comprising an extraction step of adding an organic acid extractant to a crude nickel sulphate solution to thereby extract nickel into the extractant to give a nickel-loaded organic phase, followed by a scrubbing step of scrubbing the organic phase as obtained in the previous extraction step with a nickel-containing scrub solution to thereby removing sodium and ammonia from the organic phase; and a second purifying step of adding a crude nickel sulphate solution to the nickel-retaining organic phase as obtained in the previous first purifying step so as to exchange the nickel in the organic phase with the impurities except sodium and ammonia existing in the crude nickel sulphate solution added in this step, thereby giving a purified nickel sulphate solution and an organic phase containing impurities; and optionally a third purifying step of recovering nickel from the organic phase containing impurities as obtained in the second purifying step, and a step of recovering a valuable metal, cobalt from the organic phase containing impurities.