| 摘要 |
Provided is a process for producing hematite, which is capable of producing low-sulfur-grade hematite in a HPAL process of a nickel oxide ore. Magnesium oxide produced by passing through the steps (1) to (5) is used as a neutralizing agent for preliminary neutralization treatment of a leached slurry obtained by leaching a nickel oxide ore at a high temperature and high pressure with sulfuric acid added thereto. (1) A neutralizing agent is added to a leachate, which is obtained by leaching a nickel oxide ore, to separate impurities, and a sulfurizing agent is added to the resulting neutralized solution to obtain sulfides of nickel and cobalt, followed by separating the sulfurized solution; (2) discharge waste water, which is obtained by adding a neutralizing agent to the sulfurized solution to separate aluminum and manganese, is concentrated to precipitate and separate calcium contained in the discharge waste water as calcium sulfate; (3) the resulting solution is further concentrated to precipitate magnesium in the solution as magnesium sulfate; (4) the magnesium sulfate is roasted together with a reducing agent to obtain magnesium oxide and a sulfurous gas; and (5) the magnesium oxide is washed. |
