Method for preparing chromic oxide

Abstract

The invention provides a method for preparing chromic oxide. The method comprises the following steps of: introducing reduction gas containing hydrogen into a high-temperature high-voltage reaction kettle to perform a reduction reaction on alkali metal salt of chromic acid or dichromic acid which serves as a raw material; cooling and depressurizing a reacted solution; and performing solid-liquid separation to obtain hydrated chromium sesquioxide and corresponding caustic alkali solution. By the process method provided by the invention, the corresponding caustic alkali product and the hydrated chromium sesquioxide can be prepared at the same time, and series of chromic oxide products can be prepared by further modifying the hydrated chromium sesquioxide; and the high-temperature high-pressure reaction kettle is adopted as a reactor, the reaction efficiency can be improved, and self-heat reaction can be simultaneously implemented by utilizing system reaction heat to achieve the aims of saving energy and reducing carbon emission. No waste water, waste residues or waste gas is generated in the process of preparing the chromic oxide and caustic alkali products, so that high-efficiency, energy-saving and pollution-free production of the chromic oxide can be implemented.

Description

technical field [0001] The invention relates to a production method of chromium oxide, in particular to a method for producing chromium oxide by reducing chromate or dichromate with reducing gas under hydrothermal conditions, and simultaneously producing corresponding caustic alkali solution. Background technique [0002] Chromium oxide, also known as chromium trioxide, is mainly used in metallurgy, pigments, abrasives, refractory materials, melt-blown coatings, catalysts and their carriers. Chromium oxide for metallurgy accounts for the largest proportion, followed by green pigments, which are mainly used in coatings, inks, ceramics, enamel, colored cement and other products. Chromium oxide can reflect infrared light similarly to chlorophyll, and is used to formulate camouflage paint that resembles clusters of green leaves. As an abrasive, chromium oxide is mainly used for grinding and polishing of machinery, instruments, meters, clocks and ball bearings. Chromium oxide c...

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Problems solved by technology

[0010] Chinese patent ZL01141529.0, ZL01136315.0, ZL02153523.X, ZL02153523.X, patent application publication CN100999335A (2006) etc., these methods are all with chromate and dichromate as raw material, or acidify or not acidify, adopt sugar Chromium oxide, alcohols, aldehydes, hydrazines, organic acids and other low molecular weight organic substances, or ferrous sulfate, sodium sulfide, ammonium salts as reducing agents, supplemented by different additives for acid reduction or hydrothermal reduction to obtain chromium oxide products, these research methods do not involve and consider the problem of how the reduction process of chromate and dichromate simultaneously produces alkali

[0013] In summary, as a widely used chemical raw material, although there have been a lot of researches on the production method of chromium oxide, it has great advantages in energy saving, emission reduction, clean production, reduction of production cost, increase of product added value, improvement of resource utilization rate, and improvement of production capacity. In terms of efficiency and other aspects, there is still a broad space for development and exploration

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