With the increasing demand for nickel ore and the deepening development of nickel sulfide ore, the development of laterite nickel ore has gradually become a new trend of nickel ore development. The geological structure of laterite nickel ore is relatively complex, and the nickel content and mineral composition of different deposits are very different. It is difficult to enrich it through traditional beneficiation methods. At present, the beneficiation methods of laterite nickel ore include nickel sulfur process, rotary kiln submerged arc furnace process (RKEF), sintering blast furnace reduction process, direct reduction process, acid leaching process, etc.
The enrichment of laterite nickel ore by pyrometallurgical methods such as nickel sulfur process, rotary kiln submerged arc furnace process (RKEF), sintering blast furnace reduction process and direct reduction process is limited by power supply, and there are problems such as high investment and high pollution. The beneficiation of laterite nickel ore by chemical beneficiation processes such as acid leaching is the beneficiation direction of laterite nickel ore. Fodamon studied different types of laterite nickel ores. Good beneficiation results can be obtained by using atmospheric acid leaching, pressurized acid leaching, and atmospheric + high pressure combined acid leaching to treat laterite nickel ores.
a. Atmospheric pressure acid leaching of laterite nickel ore
Atmospheric acid leaching method is applicable to laterite nickel ore with high magnesium content. Sulfuric acid and hydrochloric acid are generally used as leaching agents. In the process of treatment, the laterite nickel ore is ground to a certain concentration of pulp, added with a certain concentration of acid, the temperature is controlled to leach the nickel, cobalt, iron, magnesium, aluminum and other elements in the ore, and then treated after separation and washing; Then neutralize the pulp with alkali to remove impurities such as magnesium, iron and aluminum. After liquid-solid separation and washing, the obtained liquid is re precipitated to obtain nickel cobalt hydroxide; The remaining liquid is then neutralized to remove calcium and magnesium, and then returned to production and discharge. Iron in laterite nickel ore leaching solution is converted into iron phosphate, and then further processed into lithium iron phosphate.
b. Pressure acid leaching process of laterite nickel ore
The pressurized acid leaching process is suitable for laterite nickel ore with high limonite content and low magnesium content. First, laterite nickel ore is ground and prepared into a pulp with a stable concentration, which is preheated and leached under a stable sulfuric acid concentration. During leaching, nickel, cobalt, iron, aluminum and other elements are dissolved together. After separation and washing, impurities such as iron and aluminum enter the slag, while nickel and cobalt remain in the solution. According to the requirements of the product scheme, different processes can be used to produce high-quality nickel cobalt hydroxide, nickel cobalt sulfide or nickel cobalt sulfate crystals.
c. Atmospheric pressure + high pressure combined acid leaching process of laterite nickel ore
Atmospheric pressure high pressure two-stage acid leaching of laterite nickel ore can be used for ores containing different contents of magnesium in an ore body. The acid leaching process will produce excess acid after treatment, and neutralization treatment is required in the later purification process of the leaching solution, which will have varying degrees of impact on the subsequent impurity removal operations. Therefore, Fodamon studied the two-stage leaching process based on the two processes of Atmospheric Acid Leaching and high-pressure acid leaching, and used the combined process of atmospheric pressure leaching and high-pressure acid leaching to treat laterite nickel ore. its main purpose is to neutralize the excess acid in the leaching solution, So as to remove part of ferric iron. The free acid can be neutralized by adding the atmospheric acid leaching solution of high magnesium laterite nickel ore to the low magnesium mineral for two-stage high-pressure acid leaching.
In actual production, different lateritic nickel ores have different properties and mineral compositions, which cannot be blindly copied. It is suggested that the mine owners do a good job in Beneficiation tests, clarify the nature of the deposit, and formulate beneficiation schemes targeted to obtain ideal economic benefits.