Method of recycling nickel, cobalt, iron and silicon from low-grade laterite nickel ore through combined leaching process

Abstract

The invention discloses a method of recycling nickel, cobalt, iron and silicon from low-grade laterite nickel ore through a combined leaching process. The method includes the following steps: (a) performing washing classification to the low-grade laterite nickel ore to obtain high-silicon and -magenisum ore and low-silicon and -magenisum and high-iron ore; (b) adding heated high-silicon and -magenisum ore slurry and concentrated sulfuric acid into a double-screw material-pushing reactor; (c) dissolving reaction materials in water and performing solid-liquid separation and filter residue washing to obtain a normal-pressure leached residue, a normal-pressure leached liquid and a washing liquid; (d) performing pressurized leaching to the low-silicon and -magenisum and high-iron ore slurry and the normal-pressure leached liquid in a pressurized pot, wherein the Fe<3+> in the normal-pressure leached liquid is hydrolyzed to release acid for leaching the low-silicon and -magenisum and high-iron ore slurry again; (e) decreasing the temperature and performing the solid-liquid separation to obtain a pressurized leached residue and a pressurized leached liquid; (f) removing non-nickel and -cobalt impurities from the pressurized leached liquid, and recycling the nickel and / or the cobalt through a known method; (g) washing the pressurized leached residue through a sodium carbonate solution and washing the pressurized leached residue to obtain iron fine powder; and (h) screening the normal-pressure leached residue to obtain silicon dioxide and fine sand. The method is high in leaching rate of nickel and cobalt, is less in acid consumption and can effectively recycle iron and partial silicon.

Description

technical field [0001] The invention relates to the technical field of hydrometallurgical technology of low-grade laterite nickel ore, in particular to a method for recovering nickel, cobalt, iron and silicon from low-grade laterite nickel ore through a combined leaching process. 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 . 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. Highly regolithed layers typically have most of the nickel they contain finely distri...

AI Technical Summary

Problems solved by technology

But this method has the following disadvantages and deficiencies: First, the time for leaching limonite under normal pressure is longer, usually more than 4 hours, so the required normal pressure leaching equipment is huge; the second is that the acid consumption is higher, and the total acid / ore=0.6 / 1. Although this acid consumption index is far lower than atmospheric acid leaching, it is much higher than high-pressure acid leaching; third, the amount of saprolite ore used is twice that of limonite, which also contradicts the ore belt composition of laterite ore , it is well known that in lateritic nickel deposits, the amount of limonite: the amount of saprolite ≥ 2:1

[0009] 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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