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In the era of energy transformation, nickel is the third metal under electrification. Nickel for power batteries will usher in explosive growth with the outbreak of terminal demand for new energy vehicles and the gradual advancement of high-nickel conversion. Among the global land nickel resources , about 60% of which are in the form of laterite nickel ore. With the development of more and more laterite nickel ore projects, the nature of laterite nickel ore resources is becoming more and more understood. The general fire method is suitable for silicon-magnesium-type nickel ore with relatively high nickel content, and the wet method is suitable for limonite-type nickel ore with relatively low nickel content.
The hydrometallurgy process of lateritic nickel ore mainly includes reduction roasting-ammonia leaching (Caron process), high pressure acid leaching (HPAL), and atmospheric acid leaching (AL). The three wet processes are suitable for lateritic nickel ores with different MgO contents. Since MgO will cause unnecessary consumption of acid in the reaction, which will increase costs, HPAL is generally suitable for processing limonite ores with Mg contents less than 5%.
Although HPAL has relatively harsh reaction conditions, strict requirements on equipment, and high capital expenditure, it is the current and future mainstream route and Direction of development.
The high-pressure acid leaching process is also called the HPAL process. This process generally uses dilute sulfuric acid as the leaching solution. In a high-temperature and high-pressure environment of 240-270°C and 4-5MPa (about 40-50 times the standard atmospheric pressure), the process parameters are adjusted to make nickel and cobalt Into the leaching solution, most of the iron and silicon enter the slag, and after subsequent neutralization, impurity removal and precipitation to obtain MHP (nickel cobalt hydroxide) or MSP (nickel cobalt sulfide)
The core of the HPAL process is to ensure that nickel and cobalt are fully leached under the high temperature and high pressure reaction environment under the control of fine parameters. The whole process is divided into four parts: feed preparation, high pressure acid leaching, neutralizer CCD countercurrent washing, and precipitation.
After years of development, the HPAL process has made great improvements in process design. At present, the recovery rate of nickel and cobalt in the whole process can reach close to 96% and 94%. With the gradual maturity of the manufacturing process of large-scale high-pressure reactors and the improvement of equipment levels, the technological advantages of high-pressure acid leaching will become more and more obvious. After several generations of development, capital expenditure, construction period, and climbing period have all been greatly improved. The HPAL process is the main direction for the development of laterite nickel ore hydrometallurgy process in the future.
Looking back at the historical HPAL project, there are two main direct products of hydrometallurgy: nickel-cobalt sulfide (MSP) and nickel-cobalt hydroxide (MHP), which differ only in the final precipitation process. MSP has higher nickel and cobalt content, low water content and high purity, while MHP has lower cost, better preparation process safety, and is easy to produce nickel sulfate. Specifically:
1. From the perspective of product properties: MSP has a high nickel and cobalt content, and the nickel content can reach more than 55% (dry basis), and the water content is low, generally below 20%. The nickel content of MHP is generally 35%-40% (dry basis), but the water content of the product is relatively high, around 50%-70%. It is generally believed that the quality of the product with a water content of about 50% is relatively high.
2. From the point of view of the preparation of nickel sulfate: the preparation of nickel sulfate by MSP requires high temperature and high pressure conditions, and the investment cost is relatively high; while the preparation of nickel sulfate by MHP is a typical acid-base neutralization reaction, which has lower requirements for equipment and a simpler process. Low. According to SMM data, the production of nickel sulfate by MSP requires oxidants such as hydrogen peroxide and high-temperature and high-pressure environments, and the cost investment is relatively large. Therefore, from the perspective of historical projects, MSP is mostly electrolytically processed into electrolytic nickel and electrocobalt. MHP does not require a high-temperature and high-pressure environment, and only needs "acid dissolution-impurity removal-extraction" to obtain nickel sulfate solution. The cash cost is low, so MHP has become a mainstream source of nickel sulfate raw materials. With the successive commissioning of the Indonesian HPAL project, the proportion of MHP in nickel sulfate raw materials is expected to further increase.
Reductive acid leaching of nickel cobalt hydroxide under the action of sulfuric acid and reducing agent to obtain leachate; add catalyst, oxidant and neutralizer to the leachate, and carry out catalytic oxidation reaction and neutralization reaction at the same time to obtain the first impurity removal solution ; The first impurity removal solution is extracted and removed, evaporated and crystallized to obtain nickel sulfate.
The extraction of laterite nickel-cobalt leaching liquid has high requirements on equipment, and it is necessary to select extraction equipment with stable performance, corrosion resistance, high extraction efficiency and good extraction effect. liquid liquid centrifugal extractor, which is a green extraction process developed based on the principle of cation exchange and complex extraction in metal extraction and the new extraction equipment. It has the following special features:
①High metal extraction rate, up to 99.9%;
②Simple process flow and convenient operation;
③The quality of stripping solution obtained is stable, which can meet different production requirements;
④The residual amount of aqueous solvent after treatment is small, which can reduce The follow-up section handles the pressure;
⑤ The extraction equipment occupies a small area and has a large processing flexibility.
This series of centrifugal extraction equipment is a powerful tool for the extraction of nickel-cobalt leachate from laterite ore, and has been successfully applied to the site of industrial production cases. Welcome to visit the factory!
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