Process for preparing chromium oxide from laterite-nickel ores

Abstract

The invention provides a process for preparing chromium oxide from laterite-nickel ores. The process comprises the steps of carrying out liquid-solid separation and aluminum removal on roast materials obtained by leading the laterite-nickel ores and alkali metal hydroxide to be in molten salt reaction for obtaining alkaline leaching solution which is rich in chromate and the alkali metal hydroxide, taking the alkaline leaching solution as a raw material, taking hydrogen as a reducing agent, leading the alkaline leaching solution and the hydrogen to be in direct hydrothermal reduction reaction under certain temperature and pressure conditions for generating chromium hydroxide slurry, and carrying out the liquid-solid separation on the slurry for obtaining a chromium hydroxide filter cake and filtrate containing a small quantity of hexavalent chromium. A final product of chromium oxide is obtained by drying, high-temperature calcining and washing the chromium hydroxide filter cake; and the filtrate can be returned to the material mixing procedure for realizing the circulating material mixing. The process can effectively recycle and utilize valuable metal chromium in the laterite-nickel ores, thereby not only realizing the pluralism of a laterite-nickel ore product, but also reducing the emissions of toxic wastes, realizing the internal circulation of materials and media, being in line with the requirements on clean production; furthermore, the reduction process has simple flow process and strong industrial operationality.

Description

technical field [0001] The invention belongs to the field of nonferrous metal metallurgy, and in particular relates to a process for preparing chromium oxide from laterite nickel ore. Background technique [0002] The process of extracting nickel and cobalt from laterite nickel ore has attracted widespread attention, but there is no report on the process of extracting valuable metal chromium from laterite nickel ore and preparing chromium oxide and other related chromium products, and the comprehensive utilization of laterite ore is still unknown. Subject to further development. [0003] The chromium salt industry occupies an important position in the national economy. Its main products are sodium dichromate, chromic anhydride, potassium dichromate, basic chromium sulfate, chromium oxide, etc. It is an indispensable chemical raw material industry in the national economy. As a main chromium compound material, chromium oxide is widely used in pigment, metallurgy, catalytic sy...

AI Technical Summary

Problems solved by technology

However, this process has obvious disadvantages: high hydrogen reduction temperature leads to high energy consumption, and puts forward higher requirements for equipment safety and controllability; Hydroxides are converted to low-value by-product alkali metal salts, thereby increasing costs in disguise

However, the reaction conditions of this process are not mild enough, and the stability of gas-solid reaction is poor.

[0008] In summary, although there are many researches on the process of chromium oxide products, these processes generally have disadvantages such as high cost, complicated process, harsh reaction conditions, and environmental pollution; It has not been paid attention to by people. Therefore, it is of great practical significance to develop a clean production technology that comprehensively utilizes the valuable metal chromium in laterite nickel ore and prepares chromium oxide products.