The invention relates to a method for producing chromates through using chromium-containing waste residues. The method comprises the following steps: reacting pretreated chromium-containing waste residues with an oxidant in an alkaline solution, removing impurities of an obtained reaction solution, carrying out evaporative crystallization, and carrying out solid-liquid separation to obtain chromate products. The chromium-containing waste residues mainly comprise chromium hydroxide-containing waste residues and concretely are industrial chromium-containing wastes generated in the industrial processes comprising the metallurgy, the chemical industry, the pharmacy, the light industry and the like, wherein the main occurrence states of chromium comprise trivalent chromium salts, chromium hydroxide or hydrates thereof. The method has the advantages of short process flow, mild condition, small apparatus corrosion, low process cost, realization of the circulating regeneration of the chromium-containing waste residues, environmental pollution solving, exploitation of a new raw material for producing the chromates, and economic value creation.

Method for producing chromates through using chromium-containing waste residues

The invention relates to a method for producing sodium bichromate. The method comprises the following steps: 1) performing hydrothermal oxidation on slurry of chromium-containing sodium carbonate, ferrochromium and soda and water to obtain sodium chromate and carbon dioxide, and removing carbon dioxide; 2) separating the obtained reaction mixture to obtain a sodium chromate solution and iron slag; 3) concentrating the obtained sodium chromate solution to 600-1400g/L; 4) carbonizing and acidizing the sodium chromate concentrated solution by using the carbon dioxide removed in the step 1), thus obtaining a sodium dichromate solution and chromium-containing sodium bicarbonate; and 5) decomposing the obtained chromium-containing sodium bicarbonate into chromium-containing sodium carbonate and carbon dioxide, returning the chromium-containing sodium carbonate to the step 1), and returning carbon dioxide to the step 4). According to the method, the processes of preparing the sodium chromate solution and acidizing the sodium chromate are organically combined, comprehensive recycling of Na+ and CO2 is realized, no waste residues are generated in the whole production process, the discharge of three wastes is greatly reduced, the method is a low-carbon, cyclic and clean type process for production of sodium bichromate, and the purity of the produced sodium bichromate is high.

Method for producing high-quality sodium bichromate

The invention discloses a method for preparing a sodium chromate solution by using an electrolytic process. The method comprises the following steps: providing an electrolyzer, which comprises an electrolytic cell, a power supply, industrial ferrochrome, a cathode and a diaphragm; providing the industrial ferrochrome and the cathode in the electrolytic cell at an interval, wherein the industrial ferrochrome is electrically connected with an anode of the power supply; the cathode is electrically connected with a cathode of the power supply; an electrolyte solution is contained into the electrolytic cell, and is a sodium salt solution or a soda solution; and connecting the power supply, so as to obtain solid-liquid mixed slurry in the electrolytic cell after electrolytic reaction is carried out, and separating, so as to obtain the sodium chromate solution. In addition, the invention provides a device for preparing a sodium chromate solution by using an electrolytic process.

Device and method for preparing sodium chromate solution by using electrolytic process

The present invention provides a hydrothermal oxidation method for producing alkali metal dichromate from carbon ferrochrome, and the method comprises the following steps: formulating an initial reaction liquid by mixing carbon ferrochrome, an alkaline substance and water, in which the actual addition amount of the alkali is controlled smaller than the theoretically required amount; adding the initial reaction liquid into a reaction kettle, charging an oxidizing gas into the reaction kettle, and allowing the reaction to proceed for 0.5 to 3 h at a temperature of 150° C. to 370° C. and a pressure of 2 Mpa to 24 MPa; carrying out solid-liquid separation, cooling the resultant filtrate to a temperature of −12° C. to −20° C. to precipitate crystals, and carrying out separation by centrifuge to obtain alkali metal dichromate solution; adding CrO3 to the alkali metal dichromate solution until the degree of acidification reaches 100% or greater, concentrating the solution by evaporation, and cooling it to precipitate crystals, so as to afford alkali metal dichromate. The method has a simple process, is easy to control, and can directly produce sodium dichromate under hydrothermal conditions.

A hydrothermal oxidation method for production of alkali metal dichromate from carbon ferrochrome

The invention relates to a carbon ferrochrome liquid phase method for preparing a new energy battery raw material and a new energy source hydrogen process. The process is advanced, energy saving and environmentally friendly, free from fire coal and high temperature and high pressure, the new energy source, a plurality of new energy source battery materials, pigments, chemical engineering chromium salt and the like products can be produced in disposable by using ferrochrome as the raw material by using the liquid phase method, a series of new high-end industry chains are formed, the situations that the original product use is single in use and the production is pure are changed, the enterprise international competitiveness is greatly enhanced, the upgrading and optimization and development of the nation industry are promoted, and the process has important significance.

Carbon ferrochrome liquid phase method for preparing new energy battery raw material and new energy source hydrogen process

The invention provides a method for producing chromate with high efficiency, energy conservation and cleanness. The method uses chromium iron as a raw material, and carries out oxidation dissolution in high-temperature high-pressure aqueous alkali to separate solid and liquid after temperature and pressure reduction so as to obtain a chromate solution, water and ferric oxide or mixture of the water, ferric oxide and chrome oxide. A high-temperature high-pressure reactor is used as the reactor of the method so as to greatly improve equipment efficiency and production efficiency. The method realizes autothermal reaction by system reaction heat to achieve the aim of energy conservation, and is an energy-saving process of chromate production. The method does not need external fuel to supply heating and does not generate waste gas, and the reaction precipitate is the water and the ferric oxide or the mixture of the water, the ferric oxide and the chrome oxide, wherein the water and the ferric oxide or the mixture of the water, the ferric oxide and the chrome oxide can be used for preparing chromium iron paint without generating waste residue; and washing of the precipitate adopts countercurrent washing, and washing water is used for preparing a reaction initial solution without generating waste water. The method does not generate the three wastes, and is a clean process for producing the chromate.

High-efficiency, energy-conservation and clean method for producing chromate

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

Xinjian Yin

Papers

High-efficiency, energy-conservation and clean method for producing chromate

Method for preparing chromic oxide

A hydrothermal oxidation method for production of alkali metal dichromate from carbon ferrochrome