Method for producing aqueous solution containing nickel, cobalt and manganese

A method for producing an aqueous solution containing nickel, cobalt and manganese, comprising:

• a leaching process including a pressure-leaching process of leaching a raw material under pressure to form a leachate containing nickel, cobalt, manganese and impurities;
• an impurity removal process of removing the impurities from the leachate;
• a target substance precipitation process of precipitating a mixed hydroxide precipitate containing nickel, cobalt and manganese by introducing a neutralizing agent into a filtrate from which the impurities are removed;
• and
• a dissolution process of dissolving the mixed hydroxide precipitate in an acid,
• wherein the pressure-leaching process includes a first-stage pressure-leaching process and a second-stage pressure-leaching process of pressure-leaching a residue of the first-stage pressure-leaching process with an acidity higher than an acidity in the first-stage pressure-leaching process, and
• the impurity removal process includes a first-stage solvent extraction process of selectively extracting zinc from the impurities by introducing a first solvent extractant and a second-stage solvent extraction process of selectively extracting magnesium from the impurities by introducing a second solvent extractant.