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Nickel has the characteristics of high mechanical strength, good ductility, high temperature resistance, and high chemical stability. Therefore, it is widely used in stainless steel, new energy and other fields, and has become an indispensable metal in the construction of a modern system. There are many types of nickel ores. According to the mineral properties, nickel ores are mainly divided into copper-nickel sulfide ores and nickel oxide ores. The beneficiation and processing methods of the two are completely different. This article will describe the beneficiation method of copper-nickel sulfide ores.
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In copper-nickel ore, copper mainly exists in the form of chalcopyrite, while nickel mainly exists in the form of free nickel sulfide such as pentlandite, pyrrhotite, and pyrrhotite. A considerable part of nickel is present in pyrrhotite in the form of "isomorphism", and there is also a small amount of nickel silicate. Sulfide copper-nickel ore types are mostly magma-melted copper-nickel ore. When the nickel content is above 3%, it is a rich ore and can be smelted directly, while when the nickel content is less than 3%, it needs to be processed. Among the beneficiation methods, flotation is the main method, and gravity separation and magnetic separation are usually auxiliary.
The gravity separation method of sulfide copper-nickel ore separation uses the density difference of minerals to separate minerals by gravity separation. The magnetic separation method uses the magnetic difference of minerals to separate magnetic minerals from non-magnetic minerals through the action of magnetic field. In the process of magnetic separation of nickel ore, effective separation can be achieved by adjusting the magnetic field strength and the operating speed of the magnetic separator according to the magnetic difference between nickel ore and impurities.
For the flotation of sulfide copper-nickel ore, there are different flotation methods, including preferential flotation, mixed flotation and mixed-preferred flotation process. Preferred flotation is suitable for ores with high copper content, and can directly obtain copper concentrate with low nickel content; while mixed flotation is suitable for ores with low copper content, and copper-nickel concentrate is separated after mixed flotation. The mixed-preferred flotation process combines the advantages of the first two, firstly flotation of copper and nickel, and then separation of low-nickel copper concentrate and copper-containing nickel concentrate to improve flotation efficiency and resource recovery rate. A basic principle for determining the flotation process is that it is better to let copper enter nickel concentrate and avoid nickel entering copper concentrate as much as possible, because the nickel in copper concentrate is greatly lost during the smelting process, while the copper in nickel concentrate can be recovered more completely.
In the process of mineral processing, we need to pay special attention to different types of nickel minerals and adopt different flotation reagents and process conditions for them. Pentland pyrrhotite, pyrrhotite and nickel-containing pyrrhotite can be effectively floated by advanced xanthates such as butyl or amyl. The flotation properties of these minerals are between chalcopyrite and pyrrhotite, so better flotation effects can be obtained under different media conditions. In addition, lime is a commonly used depressant, which has a better depressant effect on pyrrhotite, while excessive lime is required for the depressant of pentlandite and pyrrhotite. At the same time, copper sulfate is an activator for pentlandite and pyrrhotite, which helps to improve flotation efficiency.
In actual operation, the beneficiation method may need to be adjusted and optimized according to the specific situation. Due to the nature of the ore, dissemination differences and other factors, the flotation effect will be different. Therefore, we need to formulate corresponding process flow and beneficiation methods according to the conditions and characteristics of each individual mine to improve the nickel ore recovery rate.
