How to Deal with Laterite Nickel Ore in Different Ore Layers
Shandong Xinhai Mining Technology & Equipment Inc.
Xinhai provides ore processing plant and full set equipment: Ball mill, Hydrocyclone, Flotation, Washing plant, CIP, CIL
Laterite nickel ore?is a clay-like ore formed by long-term weathering, leaching, and deposition of nickel oxide deposits, containing hydrous oxides such as iron, aluminum, and silicon.
Laterite nickel ore is divided into limonite layer, transition layer and humus layer according to the distribution of different ore layers. The beneficiation processes?applicable to laterite nickel ore in different ore layers are also different.
Lateritic nickel ore in limonite layer
The lateritic nickel ore in limonite layer mainly contains limonite, goethite, gibbsite, chromite, etc., and often contains a certain amount of cobalt.
Generally, this kind of lateritic nickel ore is suitable for high pressure acid leaching process, and is often treated by high-pressure acid leaching. Sulfuric acid is used to react in leaching process, which can comprehensively recover nickel, cobalt and other valuable metals. The reaction process is more friendly to the environment. Since corrosion and fouling are prone to occur during the production process, regular maintenance of equipment is required.
In addition, the alkaline leaching process is also used for this type?laterite nickel ore. This method is based on a high-concentration alkali metal or molten sodium hydroxide system.?And carbonization decomposition and ammonia leaching are applied to extract silicon, magnesium, nickel, and iron in sequence,?realizing?the comprehensive utilization of laterite nickel ore.
Lateritic nickel ore in transition layer
This layer is located between the limonite layer and humus layer, also known as the clay belt or nontronite belt, containing nontronite, silica and a small amount of goethite.?And nickel exists in the form of different oxides. The treatment process of this kind of laterite nickel ore mainly includes atmospheric pressure acid leaching process, reduction roasting-ammonia leaching process, and small blast furnace process.
The steps of atmospheric pressure acid leaching include pulp preparation, nickel leaching, nickel precipitation recovery. This process can realize the enrichment of nickel.?The use of organic acid has less environmental pollution,?and the maintenance cost of equipment is low.
The main process of the reduction roasting-ammonia leaching includes laterite nickel ore drying, reduction roasting, multi-stage countercurrent ammonia leaching, selective precipitation to obtain carbonate precipitation, and calcination to obtain nickel block products. The process flow is relatively long, and reagents can be recycled. Nickel and cobalt can be recovered comprehensively effectively.
The small blast furnace process is mainly to produce medium-nickel iron with a nickel content of 5% to 8% in a small blast furnace of less than 200 cubic meters.?Nickel and iron?can be recovered from laterite nickel ore.
Laterite nickel ore in humus layer
This layer mainly includes quartz, talc, serpentine, olivine and other minerals. The nickel content is relatively high, but the chemical composition and mineral composition are not uniform. Recycling is carried out by reduction roasting-magnetic separation process, rotary kiln pre-reduction-electric furnace smelting process, reduction roasting-acid leaching process, hydrothermal method.
The reduction roasting-magnetic separation process mainly includes two stages:?the reduction of iron-nickel oxide and the growth of iron-nickel particles. This process utilizes the reduction process to promote the growth of metal particles. Coal powder is generally used as a reducing agent to enrich nickel and iron in the laterite nickel ore, and reduce the laterite nickel ore to metallic iron and nickel at a temperature lower than the melting point of the ore, so that the nickel-iron alloy can be effectively separated.
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The rotary kiln pre-reduction-electric furnace smelting process mainly includes drying, calcination, pre-reduction and smelting processes. Laterite nickel ore contains a large amount of free water and bound water, which needs to be removed by drying and calcination?processes. In?high temperature environment, nickel ore is reduced by reducing gas, and a good nickel recovery rate can be obtained after smelting. This process is suitable for processing laterite nickel ore with higher nickel grade, but it cannot recover cobalt minerals.
The reduction roasting-acid leaching process is carried out at room temperature, which can reduce the dissolution of iron. The leaching rate is relative high and the selectivity is good. It is suitable for laterite nickel in the humus layer with high nickel and cobalt content.
The hydrothermal method is carried out in a closed pressure vessel and water is used as solvent. According to different reaction types, it can be divided into hydrothermal oxidation, hydrothermal reduction, hydrothermal precipitation, hydrothermal synthesis, hydrothermal hydrolysis, hydrothermal crystallization, etc. Among them, hydrothermal crystallization is more common and can be used to treat humus-type laterite nickel ore.
In actual production, the nature of raw laterite nickel?ore changes with the mining limit, which needs to be considered according to the actual situation. Therefore, the process plan before the concentrator should be formulated scientifically and rationally through beneficiation test and design, so as to achieve ideal economic benefits.
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