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AssigneeSumitomo Metal Mining Co., Ltd.
InventorsYoshitomo Ozaki, Jun-ichi Takahashi, Yu Yamashita, Hideki Ohara
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It is an object to provide a method for producing magnesium oxide by which magnesium oxide being high in purity and low in impurity content can be produced simply and efficiently from a sulfuric acid solution containing magnesium and calcium such as waste water. In the present invention, calcium is precipitated as calcium sulfate and separated by concentrating a sulfuric acid solution containing magnesium and calcium, and magnesium is precipitated as magnesium sulfate and separated by further concentrating the solution resulting from the separation of calcium. The separated magnesium sulfate is roasted together with a reductant, so that magnesium oxide and sulfur dioxide are obtained. The resulting magnesium oxide is washed to produce magnesium oxide with high purity.
An operating method in hydrometallurgy of nickel oxide ore comprising a leaching step of adding sulfuric acid to a slurry of nickel oxide ore to leach the ore under high temperature and pressure conditions, a solid-liquid separation step of separating a leach residue to obtain a leachate, a neutralization step of adding a neutralizing agent to the leachate and separating a neutralized precipitate containing the impurity to obtain a neutralization final liquid containing nickel and cobalt, and a sulfurization step of subjecting the neutralization final liquid to sulfurization treatment to obtain sulfide and barren liquor containing nickel and cobalt, wherein
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Dependencies are inferred from the claim text.