Method for producing magnesium oxide by hydrochloric acid normal pressure acid leaching laterite nickel ore waste liquid

The invention belongs to the technical field of metal hydrometallurgy, and provides a method for producing magnesium oxide by hydrochloric acid normal-pressure acid leaching of laterite-nickel ore waste liquid, which comprises the following steps: mixing the waste liquid and an oxidant to obtain filtrate; and sequentially concentrating, roasting and dissolving the filtrate to obtain the magnesium oxide. After the pH value of the magnesium-containing waste liquid is adjusted with the alkali liquor, the magnesium-containing waste liquid and the oxidizing agent are heated and stirred to react to generate the manganese-containing oxide precipitate, magnesium ions are reserved in the solution, and the method has the advantages that the impurity removal rate is high, other impurities are not introduced, and the cost is low; sodium chloride, potassium chloride and magnesium chloride in the solution are concentrated, crystallized, mixed and roasted together, so that sub-molten salt is formed, the temperature required