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 in 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 concentrate through traditional methods, including nickel sulfur process, rotary kiln submerged arc furnace process (RKEF), sintering blast furnace reduction process, direct reduction process, acid leaching process, etc.
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 greatly limited by power supply, and there are problems such as high investment and high pollution. The use of acid leaching and other chemical beneficiation processes for laterite nickel ore beneficiation is the direction of laterite nickel ore beneficiation. Xinhai Ore Loading Co., Ltd. conducts research on different types of laterite nickel ores, and adopts atmospheric acid leaching, pressurized acid leaching, atmospheric+high-pressure combined acid leaching to treat laterite nickel ores, which can obtain good beneficiation results.
The atmospheric acid leaching method is applicable to the treatment of laterite nickel ore with high magnesium content. Generally, sulfuric acid and hydrochloric acid are used as leachants. In the process of treatment, the laterite nickel ore is first ground into slurry of a certain concentration, added with acid of a certain concentration, and 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, aluminum, etc. After liquid-solid separation and washing, the liquid obtained can be re precipitated to obtain nickel cobalt hydroxide; The remaining liquid is neutralized and calcium and magnesium are removed to return to production and discharge. The iron in the leaching solution of laterite nickel ore is converted into iron phosphate, which is further processed into lithium iron phosphate.
The pressurized acid leaching process is suitable for treating laterite nickel ores with high limonite content and low magnesium content. First, the laterite nickel ore is ground into a slurry with a stable concentration, and then it 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, the impurities such as iron, aluminum and others 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 crystal.
The secondary acid leaching of laterite nickel ore under atmospheric pressure and high pressure can be used to treat ores with different magnesium contents in an ore body. The acid leaching process will produce excess acid after treatment, and neutralization treatment is required in the purification process of the later leaching solution, which will affect the subsequent impurity removal operations to varying degrees. Therefore, Xinhai Mine has studied the two-stage leaching process on the basis of atmospheric acid leaching and high-pressure acid leaching. The combined process of atmospheric pressure leaching and high-pressure acid leaching is used to treat laterite nickel ores. Its main purpose is to neutralize the excess acid in the leaching solution, Thus, part of ferric iron is removed. Adding acid leaching solution of high magnesium laterite nickel ore under normal pressure to low magnesium laterite nickel ore for two-stage high-pressure acid leaching can neutralize free acid.
In actual production, different laterite nickel ores have different properties and mineral compositions, which cannot be blindly copied. It is recommended that the mine owners do a good job, clarify the nature of the deposit, and formulate a targeted beneficiation plan to obtain ideal economic benefits.
