Method for extracting sodium thiocyanate, sodium thiosulfate and sodium sulfate from desulphurization waste liquid of oven gasalkali process

A technology of sodium thiosulfate and desulfurization waste liquid, which is applied in the direction of thiosulfate/dithionite/polythionate, alkali metal sulfite/sulfate purification, thiocyanate, etc., and can solve the problem of equipment Corrosion, increasing the load of the gas purification system, reducing the service life and other problems, achieving good economic benefits and realizing the effect of resource reuse

Inactive Publication Date: 2019-05-31
扬州康龙环保工程有限公司
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Problems solved by technology

This method has the following disadvantages: with the increase of environmental protection pressure, the mixed salt of sodium thiosulfate and sodium sulfate is waste solid, which cannot be treated. Subsequent equipment caused severe corrosion and reduced service life

Method used

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  • Method for extracting sodium thiocyanate, sodium thiosulfate and sodium sulfate from desulphurization waste liquid of oven gasalkali process

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Embodiment 1

[0033] A method for extracting sodium thiocyanate, sodium thiosulfate and sodium sulfate from coke oven gas-alkali desulfurization waste liquid. The mixed salt obtained by evaporating and concentrating the desulfurization waste liquid is extracted with an organic solvent to obtain sodium thiocyanate product. During the process, the whole process of nitrogen protection is adopted, and nitrogen is filled from the air inlet of the centrifuge for protection. Sodium thiocyanate is extracted with an organic solvent. The organic solvent is easy to catch fire and explode, and the extracted sodium thiocyanate has a high temperature environment during the centrifugation process. , It is easy to catch fire and explode, so it is protected by nitrogen; the mixed salt of sodium thiosulfate and sodium sulfate is separated by fractional crystallization to obtain sodium thiosulfate products and sodium sulfate products. Include the following steps:

[0034] (1) One-time evaporation: decolorize ...

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Abstract

The invention discloses a method for extracting sodium thiocyanate, sodium thiosulfate and sodium sulfate from desulphurization waste liquidof oven gas alkali process, and belongs to the technical field of chemical environmental protection.The method comprises the following steps of: evaporating and concentrating the desulfurization waste liquid to obtain mixed salt; extracting the mixed salt by using an organic solvent; using nitrogen for protection in a whole extraction process; extracting to obtain a sodium thiocyanate product; and separating the mixed salt of the sodium thiosulfate and sodium sulfate by adopting a fractional crystallization method to obtain a sodium thiosulfate product and a sodium sulfate product.By the adoption of the method for extracting the sodium thiocyanate,sodium thiosulfate and sodium sulfate from the desulphurization waste liquidof the oven gas alkali process, the sodium thiocyanate product, the sodium thiosulfate product and the sodium sulfate product are obtained, and obtained products have higher purity and better economic benefits are achieved.The purity of the sodium thiocyanate product reaches about 96 percent, the purity of the sodium thiosulfate product reaches about 96 percent, the content of the sodium thiosulfate in the sodium sulfate product is less than or equal to 0.5 percent, and the content of the sodium thiocyanate is less than orequal to 1 percent, thereby meeting the sales requirement.

Description

technical field [0001] The invention belongs to the technical field of chemical environmental protection, and in particular relates to a method for extracting sodium thiocyanate, sodium thiosulfate and sodium sulfate from coke oven gas-alkali desulfurization waste liquid. Background technique [0002] Hydrogen sulfide in coke oven gas is desulfurized using sodium carbonate as alkali source and PDS as catalyst. During the desulfurization process, the desulfurization liquid continuously generates sodium thiosulfate, sodium thiocyanate and other salts. When the salt content in the desulfurization liquid reaches a certain value, the desulfurization efficiency will decrease significantly. To maintain the desulfurization efficiency, a certain amount of desulfurization liquid must be replaced every day to maintain the balance of the total salt content in the desulfurization liquid. [0003] The desulfurization liquid replaced in the desulfurization system is the most difficult par...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B17/64C01C3/20C01D5/16
Inventor 李学龙马小军车峰
Owner 扬州康龙环保工程有限公司
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