Hematite manufacturing process and hematite manufactured by same

A process for producing hematite comprising

• (a) preparing a slurry wherein a sulfuric acid solution is added to a nickel oxide ore that contains cobalt and other metals,
• (b) leaching nickel and cobalt in the slurry at a high temperature and high pressure,
• (c) adding magnesium oxide as a first neutralizing agent to the slurry to adjust pH,
• (d) separating the slurry into a leachate containing nickel and cobalt and leached residue as hematite,
• (e) recovering the hematite,
• (f) adding a second neutralizing agent to the leachate to separate impurities, and adding a sulfurizing agent to the resulting neutralized solution to obtain a sulfurized solution and sulfides of nickel and cobalt, and separating the sulfurized solution,
• (g) adding a third neutralizing agent to the sulfurized solution to separate aluminum and manganese from the sulfurized solution and then concentrating the sulfurized solution to an end point at which the specific gravity of the concentrated sulfurized solution reaches 1.1 to 1.3 g/cm3, thereby to precipitate and separate calcium as calcium sulfate and produce a separated solution,
• (h) crystallizing magnesium sulfate from the separated solution of step (g) and separating the magnesium sulfate,
• (i) roasting the magnesium sulfate with a reducing agent producing magnesium oxide and a sulfurous acid gas, and
• (j) washing the magnesium oxide from step (i), and recycling the magnesium oxide as an addition to the first neutralization agent in step (c).