Operating method in hydrometallurgy of nickel oxide ore

摘要

The purpose of the present invention is to provide a method for producing magnesium oxide, according to which highly-pure magnesium oxide having a low content of impurities can be simply and efficiently produced from a sulfuric acid solution containing magnesium and calcium such as waste water. According to the present invention, a sulfuric acid solution containing magnesium and calcium is concentrated in order to precipitate and separate the calcium as calcium sulfate, and a solution obtained from the calcium separation is further concentrated in order to precipitate and separate the magnesium as magnesium sulfate. The separated magnesium sulfate is subjected to roasting together with a reducing agent and magnesium oxide and sulfurous acid gas are obtained. The resulting magnesium oxide is washed thereby producing highly-pure magnesium oxide.