Method for extracting sodium carbonate and sodium thiocyanate from sodium-alkali desulfurization waste liquid by causticization-acidification

A technology for desulfurization waste liquid and sodium thiocyanate, which is applied to chemical instruments and methods, thiocyanic acid, carbonate preparations, etc., can solve the problems of high construction and maintenance costs of production equipment, long waste liquid treatment process routes, and overall Low economic benefits and other problems, to achieve the effect of saving the refrigerator system, low operating costs, and simple installation

Inactive Publication Date: 2015-12-09
ANHUI UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

The disadvantage of this method is that the waste liquid treatment process route is long, the added value of the product is not high, the construction cost and maintenance cost of the production device are high, so the overall economic benefit is low, and the more expensive sodium thiocyanate in the waste liquid is not recovered.

Method used

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  • Method for extracting sodium carbonate and sodium thiocyanate from sodium-alkali desulfurization waste liquid by causticization-acidification

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Embodiment Construction

[0039] The method of the present invention firstly puts the sodium-alkali desulfurization waste liquid, that is, the raw material solution A, into the filter 1, and the filter 1 has built-in coke or activated carbon or other adsorption materials, and the raw material solution A is adsorbed after passing through the coke or activated carbon adsorption materials at normal temperature and pressure. To separate the solid impurities entrained in the waste liquid, the filter can be operated continuously for several weeks or even months. When the adsorption reaches saturation or the resistance increases, the adsorber can be kept working normally by backflushing or replacing the adsorbent.

[0040] Send the raw material liquid A after preliminary purification into the thermal decomposer 2, and heat it with steam S, so that components such as sodium thiosulfate and sodium polysulfide are decomposed into sodium sulfite and sodium sulfide, and elemental sulfur is precipitated and part of t...

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Abstract

The inventi on discloses a method for extracting sodium carbonate and sodium thiocyanate from sodium alkali desulfurization liquid waste by using a causticization-acidification method and belongs to the technical field of desulfurization liquid waste treatment. The method comprises the following processes: pertreating liquid waste for removing impurities, heating for decomposing and discoloring, and carrying out oxidizing causticization-separation, acidification-separation, evaporation and concentration, and cooling crystallization-separation. The method is used for treating the desulfurization liquid waste generated in a production process of removing hydrogen sulfide and hydrogen cyanide out of coal gas or other gases by using a sodium alkali method. According to the method provided by the invention, sodium thiosulfate, sodium polysulfide and sodium sulfate in the sodium alkali desulfurization liquid waste can be converted into calcium sulfite, calcium sulphide and calcium sulfate precipitations at normal temperature through heating decomposition, oxidization and causticization; meanwhile, high-purity sodium carbonate and sodium thiocyanate are extracted, the sodium alkali is recovered to return a gas desulfurization system cycle, and the alkali consumption of the desulfurization operation is reduced.

Description

Technical field: [0001] The invention belongs to the technical field of desulfurization waste liquid treatment, and in particular relates to a method for extracting sodium carbonate and sodium thiocyanate from sodium-alkali desulfurization waste liquid by a causticization-acidification method. Background technique: [0002] In the fields of coal chemical industry, petrochemical industry, natural gas and other chemical industries, the wet catalytic oxidation process is used to remove hydrogen sulfide from gas. At the same time, elements or compounds such as hydrogen cyanide, oxygen, sulfur, and alkali are present, so the side reaction of forming salt occurs at the same time. When sodium carbonate is used as the alkali source, the auxiliary salts generated are mainly sodium thiocyanate, sodium thiosulfate, sodium polysulfide, sodium sulfate, etc. The accumulation of side reaction salts will reduce the absorption capacity of the desulfurization liquid, so the part must be disch...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01D7/07C01C3/20C02F9/10
Inventor 崔平江静张超群
Owner ANHUI UNIVERSITY OF TECHNOLOGY
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