Method for recovering nickel, cobalt, iron and silicon from low-grade laterite-nickel ore by combined leaching process

Abstract

The invention discloses a method for recovering nickel, cobalt, iron and silicon from low-grade laterite-nickel ore by a combined leaching process. The method comprises the following steps: washing and grading the low-grade laterite-nickel ore to obtain high-silicon magnesium ore and low-silicon magnesium and high-iron ore; adding high-silicon magnesium ore slurry after heating and concentrated sulfuric acid into a double-spiral material pushing reactor; dissolving reaction materials in water, then performing solid-liquid separation, and washing filtration residues to obtain normal-pressure leaching residues, a normal-pressure leaching solution and a washing solution; respectively heating low-silicon magnesium and high-iron ore slurry and the normal-pressure leaching solution, then adding into a pressurization pipeline reactor for pressurization and leaching, hydrolyzing Fe<3+> in the normal-pressure leaching solution to release acid, and re-leaching the low-silicon magnesium and high-iron ore; reducing the temperature, and performing solid-liquid separation to obtain pressurized leaching residues and a pressurized leaching solution; removing impurities in the pressurized leaching solution, and then recovering nickel and/or cobalt; washing the pressurized leaching residues with a soda ash solution, and then drying to obtain fine iron powder; and performing treatment on the normal-pressure leaching residues to obtain silicon dioxide and fine sand. The method disclosed by the invention has the advantages of short leaching time, high nickel leaching rate, low acid consumption and effective recovery of iron and part of 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 conclusion, in the invention patents of lateritic nickel ore hydrometallurgy mentioned above, the disadvantages of high-pressure acid leaching (HPAL) process and improved high-pressure acid leaching process are: complex High-temperature, high-pressure autoclaves and related equipment are expensive to install and maintain; the HPAL process consumes more sulfuric acid than is required to stoichiometrically dissolve the non-ferrous metal components in the ore; the HPAL process is limited to processing mainly It is the raw material of limonite; during the operation of the HPAL process, the autoclave is prone to fouling, and it needs to be shut down for cleaning regularly, 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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