| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a solvent extraction method for obtaining high purity nickel sulfate having a low content of impurities, particularly Mg. <P>SOLUTION: In a method for producing nickel sulfate, treatment is carried out by a solvent extraction step comprising: a first step of bringing a solution prepared by acid leaching of a sulfide containing Ni and Co into contact with an extraction solvent having extractant concentration of 15-30 vol.% and a crude nickel sulfate solution at pH 6.0-7.0, whereby Ni is extracted to obtain a nickel-holding organic phase; a second step of mixing the nickel-holding organic phase with an Ni-containing cleaning liquid, whereby Na and NH<SB POS="POST">4</SB>ions contained in the nickel-holding organic phase are separated and shifted to the cleaning liquid to obtain a nickel-holding organic phase after cleaning; and a third step of reacting the nickel-holding organic phase after cleaning with a nickel sulfate solution having a composition in which the concentration ratio between Mg and Ni, Mg/Ni is in the range of 0.001-0.004, whereby Ni in the nickel-holding organic phase is replaced by impurities contained in the nickel sulfate solution to obtain an organic phase after back extraction and a nickel sulfate solution after impurity separation. <P>COPYRIGHT: (C)2013,JPO&INPIT |
