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Method for recovering thiocyanate from coke oven gas desulfuration and decyanation wastewater

A technology for desulfurization and decyanation, coke oven gas, applied in the direction of thiocyanate, etc., can solve the problems of ammonium thiocyanate purity is only 97%, can not be used as industrial grade, the resulting purity is not high, to avoid repeated recrystallization, color The effect of whitening and simplifying the processing process

Active Publication Date: 2012-04-25
江苏燎原环保科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is still difficult to separate XX, the resulting ammonium thiocyanate purity is only 97%, can not be used as industrial grade
[0017] Although there have been many studies and reports on the separation of desulfurization wastewater, the method is complicated and the resulting purity is not high. There is still room for improvement in the above method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] After the coke oven gas desulfurization and decyanation wastewater is decolorized, some organic and mechanical impurities are removed, and ammonium persulfate is added to react with the ammonium thiosulfate in the wastewater, and the ammonium thiosulfate is oxidized with ammonium persulfate to produce sulfur, ammonium hydrogen sulfate, Remove sulfur, add ammonia water to convert ammonium bisulfate into ammonium sulfate, so that the wastewater is changed from a three-component mixture of ammonium thiocyanate, ammonium thiosulfate and ammonium sulfate to two groups of ammonium thiocyanate and ammonium sulfate that are easy to crystallize and separate Part of the mixed liquid is then subjected to multi-effect concentration, and the ammonium sulfate is separated while it is hot, and the liquid ammonium thiocyanate is naturally cooled to obtain ammonium thiocyanate crystals, and the purity can reach 99%. The multi-effect concentration temperature is 75-85°C, and the concentrat...

Embodiment 2

[0033] After the coke oven gas desulfurization and decyanation wastewater is decolorized, some organic and mechanical impurities are removed. Sulfuric acid, sulfuric acid and ammonium thiosulfate are added to react, so that the desulfurization and decyanation wastewater becomes a two-component mixture of ammonium thiocyanate and ammonium sulfate. Perform multi-effect concentration, separate ammonium sulfate while hot, and naturally cool liquid ammonium thiocyanate to obtain ammonium thiocyanate crystals with a purity of 99%. The multi-effect concentration temperature is 65°C, and the concentration of the concentrated solution is 95wt%. The thermal separation temperature of ammonium sulfate is 50°C. The degree of vacuum is -0.06Mpa. The separation temperature of ammonium thiocyanate is 50°C, vacuum degree: 0.1Mpa, crystallization at room temperature.

Embodiment 3

[0035] After the coke oven gas desulfurization and decyanation wastewater is decolorized, some organic and mechanical impurities are removed, and ammonium persulfate is added to react with the ammonium thiosulfate in the wastewater, and the ammonium thiosulfate is oxidized with ammonium persulfate to produce sulfur, ammonium hydrogen sulfate, Remove sulfur, add ammonia water to convert ammonium bisulfate into ammonium sulfate, so that the wastewater is changed from a three-component mixture of ammonium thiocyanate, ammonium thiosulfate and ammonium sulfate to two groups of ammonium thiocyanate and ammonium sulfate that are easy to crystallize and separate Part of the mixed liquid is then subjected to multi-effect concentration, and the ammonium sulfate is separated while it is hot, and the liquid ammonium thiocyanate is naturally cooled to obtain ammonium thiocyanate crystals, and the purity can reach 99%. The multi-effect concentration temperature is 90°C, and the concentration...

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PUM

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Abstract

The invention discloses a method for recovering thiocyanate from coke oven gas desulfuration and decyanation wastewater. The method comprises the steps of: adding persulfate or sulfuric acid to polyamine salt wastewater for reacting with ammonium thiosulfate so as to generate ammonium sulfate and ammonium sulfite, and further oxidizing into ammonium sulfate and sulfur, thus the wastewater is changed into a two-component mixed liquid which contains ammonium thiocyanate and ammonium sulfate and is easy to separate by crystallization from a three-component mixed liquid, and high-efficiency separation is realized. The purity of the obtained ammonium thiocyanate crystal can reach 99%.

Description

Technical field [0001] The invention relates to a method for recovering thiocyanate by using coke oven gas desulfurization and decyanation wastewater, in particular to a method for directly using coke oven gas desulfurization and decyanation wastewater to recover ammonium thiocyanate, ammonium sulfate and sulfur. Background technique [0002] During the coking process of coal, about 30-35% of the sulfur is converted into hydrogen sulfide and other sulfides, which enter the coal gas together with hydrogen cyanide, forming gaseous impurities. Coke oven gas generally contains 5-8g / m of hydrogen sulfide 3 , Hydrogen cyanide 1-2.5g / m 3 . Hydrogen sulfide and hydrogen cyanide are highly corrosive and toxic, and cause extremely strong corrosion to production equipment and pipelines. They can also cause poisoning and deactivation of synthesis gas chemical reaction catalysts, which seriously affect the yield and quality of the final product. [0003] For this reason, after the mixed gas is...

Claims

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Application Information

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IPC IPC(8): C01C3/20
Inventor 冯启明吴永平吴战平储正相王思回周庆
Owner 江苏燎原环保科技股份有限公司
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