Hebei Messi Biology Co., Ltd. stated that the main advantages of the active magnesium oxide process for hydrometallurgy of nickel-cobalt ore are low acid consumption, high nickel-cobalt leaching rate, low neutralizer consumption and high purity of the leachate. The process flow is shown in the figure.
The specific process is: limonite-type laterite nickel ore is leached under pressure with sulfuric acid, and the flash slurry obtained is directly used for neutralization leaching with laterite nickel ore containing high-magnesium humus layer, and the waste heat of the slurry after flash evaporation is used for direct reaction. At the same time, in the presence of K+, Na+, and NH4+, by adding seed crystals, more than 80% of the iron in the solution forms yellow potassium ferroaluminate precipitation, and then limestone slurry is added to promote the formation of more yellow potassium ferroaluminate. The leaching rate of nickel in the neutralization leaching process can reach more than 89%, and the iron content of the leachate is less than 3g/L. Magnesium oxide is added to the neutralization leachate to produce a nickel-cobalt mixed product, which is finally sent to the refinery for refining.
Magnesium oxide precipitation technology has been applied in Australian projects. The precipitation temperature of this technology is about 60-70°C, the nickel-cobalt precipitation rate is about 95%, the water content of the product is 40%-50%, and the Ni grade in the product is ~40%.