Chromic oxide and preparation method thereof

Abstract

The invention provides chromic oxide and a preparation method thereof. The method comprises the following steps: feeding a hexavalent chromium salt solution containing seed crystal into a reaction device, feeding protective gas, sealing the device and rising the temperature, and continuously feeding reducing gas to perform reaction after target temperature is achieved, so as to obtain mixed slurry; performing solid-liquid separation on the obtained mixed slurry, and performing calcination on obtained hydroxyl chromic oxide powder, so as to obtain chromic oxide. The method has the advantages that hexavalent chromium salt is adopted to prepare chromic oxide through a hydrothermal reduction method, the reduction reaction rate is improved through adding of the seed crystal, and regulation of the reducing gas and reaction conditions, the controllability of a reaction process is enhanced, the percent reduction can reach greater than 99.2 percent, reduction products are uniform in phase, sizedistribution is narrow, and the quality of obtained chromic oxide is high and can reach the standard of pigment grade chromic oxide; the method is short in flow, and low in energy consumption and cost, does not produce pollutant emission, belongs to a clean production technology, and has significant economic benefit.

Description

technical field [0001] The invention belongs to the technical field of material preparation, and relates to a chromium oxide and a preparation method thereof, in particular to a method for preparing pigment grade chromium oxide by hydrothermal reduction. Background technique [0002] Chromium oxide (Cr 2 o 3 ) is an important industrial raw material, which is widely used in the fields of metallurgy, pigments, ceramics, coatings, green polishing, and organic catalytic synthesis. Currently, the industrial production of Cr 2 o 3 The methods mainly include chromic anhydride thermal decomposition method and hexavalent chromium salt reduction method. The thermal decomposition method of chromic anhydride uses chromic anhydride as raw material and calcines at high temperature to prepare Cr 2 o 3 , this method is expensive and pollutes seriously. The hexavalent chromium salt reduction method uses sulfur or sulfide as a reducing agent to prepare Cr through wet or dry reduction ...

AI Technical Summary

Problems solved by technology

The thermal decomposition method of chromic anhydride uses chromic anhydride as raw material and calcines at high temperature to prepare Cr 2 o 3 , this method is expensive and pollutes seriously

The hexavalent chromium salt reduction method uses sulfur or sulfide as a reducing agent to prepare Cr through wet or dry reduction of hexavalent chromium salt. 2 o 3 , mainly include sodium chromate alkaline liquid sulfur or sodium sulfide reduction method, potassium dichromate sulfur roasting reduction method, sodium dichromate ammonium sulfate reduction method, etc. The above methods have a long process and the introduction of impurity sulfur makes it difficult to obtain high-quality products and other issues, and will produce low value-added by-products in the production process

In this method, the reducing gas is introduced in advance, and then the reaction is heated. The reaction process is difficult to control, resulting in uneven composition of the product, poor performance, and the problem of high reaction temperature and pressure.

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