New method for recovering nickel, cobalt, iron, silicon and magnesium from low-grade laterite-nickel ore

Abstract

A new method for recovering nickel, cobalt, iron, silicon and magnesium from low-grade laterite-nickel ore is disclosed. The new method comprises the following steps: washing and grading; carrying out a reaction by adding enough concentrated sulfuric acid into high-silica magnesite ore pulp, and carrying out solid-liquid separation to obtain atmospheric pressure leaching residues and an atmospheric pressure leaching agent; adding the atmospheric pressure leaching agent and low-silica magnesite high-iron ore pulp in proportion into a tubular reactor and carrying out pressure leaching; carrying out solid-liquid separation; purifying and precipitating a pressure leaching filtrate by the use of magnesium oxide and filtering to obtain nickel hydroxide (cobalt hydroxide); carrying out evaporative crystallization on a nickel-precipitated liquid so as to obtain magnesium sulfate heptahydrate; washing and drying pressure leaching residues to obtain fine iron powder; and screening the atmospheric pressure leaching residues to obtain a silicon dioxide product and building sand. The method has advantages as follows: wide application range of lateritic ore; high Ni-Co leaching rate; small atmospheric pressure leaching equipment; short time; high efficiency; and low sulfuric acid consumption. As the middle and low pressure tubular reactor is adopted for pressure leaching, the defect that autoclave equipment is expensive and easy to scale is avoided. Main components of ore, such as iron, magnesium and part of silicon, can be recovered economically and effectively. The amount of waste residues is low, and the waste residues can be utilized effectively.

Description

technical field [0001] The invention belongs to the field of metallurgy, is a wet leaching process, and relates to a new method for recovering nickel, cobalt, iron, silicon and magnesium from low-grade laterite nickel ore. Background technique [0002] Laterite ore is a nickel oxide ore formed by nickel-bearing peridotite after large-scale long-term weathering and leaching metamorphism in tropical or subtropical regions. Due to differences in geographical location, climatic conditions and weathering degrees, the types of laterite ore around the world are not completely the same . [0003] The weathering process generally produces layered deposits in which complete or most complete weathering is present near the surface, gradually becoming less weathered with increasing depth, and finally terminating at some deeper depth as unweathered rock. [0004] Highly regolithed layers typically have most of the nickel they contain finely distributed in finely divided goethite grains....

AI Technical Summary

Problems solved by technology

For example, the invention patent with the publication number CN101273146A proposes a two-step normal-pressure leaching method for simultaneously extracting limonite and saprolite or leaching limonite and then saprolite ore. This method has the advantage of not using an autoclave. However, in the process described in the application, it is proposed that when the leaching solution is treated to remove Fe and / or Al, it is necessary to add a neutralizing agent to neutralize the residual acid in the leaching solution, so that most of the iron is in the form of ferric hydroxide Deposition, which will cause loss of valuable elements such as nickel and cobalt and difficulty in slurry filtration

Another example is the patent of invention whose publication number is CN101541985A, which proposes a method for leaching a mixture of limonite and saprolite at normal pressure, but its iron precipitation product is jarosite, which contains sulfate radicals, so It will increase the acid consumption of the leaching process; and jarosite is a thermodynamically unstable compound, which will release sulfuric acid during accumulation and storage, thereby causing environmental pollution

Another example is the invention patent of CN101006190A with the publication number, which proposes a method for treating the mixture of limonite and saprolite ore with concentrated acid and then leaching nickel and cobalt with water. The iron deposit produced by this method is except jarosite. Ferric oxide or hydroxide, but the leaching time of this application needs 12-48h, and the leaching time is longer, resulting in a longer process cycle and increased production costs

[0018] In short, in the above-mentioned invention patents of lateritic nickel ore wet smelting, the disadvantages of the high-pressure acid leaching (HPAL) process and the improved high-pressure acid leaching process are: complex high-temperature, high-pressure autoclaves and related equipment are required, and their installation and Both are expensive to maintain; the HPAL process consumes more sulfuric acid than is required to stoichiometrically dissolve the non-ferrous components of the ore; the HPAL process is limited to processing mainly limonite-type feedstock; the HPAL process operates at high pressure The kettle is prone to fouling, and needs to be shut down regularly for cleaning, and the operating rate is low

The disadvantages of the atmospheric pressure acid leaching process and the improved atmospheric pressure acid leaching process are: high sulfuric acid consumption; low nickel and cobalt leaching rates; long reaction time and huge equipment required

The common disadvantage of high-pressure acid leaching including improved high-pressure acid leaching process and atmospheric pressure acid leaching process including improved atmospheric pressure acid leaching process is that the amount of leaching slag is large, and it is a mixed slag of silicon and iron, so that the main component of laterite ore, iron, cannot Economical and effective development and utilization

Although the invention patent of CN102206749A mentions the recycling of leaching slag, since the silicon dioxide, iron oxide, goethite, etc. Simple magnetic separation and other methods separate them, so the economic benefits of the development and utilization of the above-mentioned leaching slag are very poor, and they can only be treated as waste solids, and even the leaching slag with a low nickel leaching rate must be treated as hazardous waste.

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