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

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

Active Publication Date: 2013-06-12
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, part of the organic and mechanical impurities are removed, ammonium persulfate is added to react with ammonium thiosulfate in the wastewater, and ammonium thiosulfate is oxidized with ammonium persulfate to generate sulfur, ammonium bisulfate, Sulfur is removed, ammonia water is added to convert ammonium bisulfate into ammonium sulfate, and the waste water is changed from a three-component mixture of ammonium thiocyanate, ammonium thiosulfate and ammonium sulfate into a two-component mixture of ammonium thiocyanate and ammonium sulfate that is easy to crystallize and separate Parts of the mixed solution, followed by multi-effect concentration, separation of ammonium sulfate while hot, and natural cooling of liquid ammonium thiocyanate to obtain crystals of ammonium thiocyanate, the purity of which can reach 99%. The multi-effect concentration temperature is 75-85° C., and the concentrated ...

Embodiment 2

[0033] After the coke oven gas desulfurization and decyanation wastewater is decolorized, part of the organic and mechanical impurities are removed, sulfuric acid is added, sulfuric acid reacts with ammonium thiosulfate, and the desulfurization and decyanation wastewater becomes a two-component mixture of ammonium thiocyanate and ammonium sulfate. Carry out multi-effect concentration, separate ammonium sulfate while it is hot, and naturally cool down the liquid ammonium thiocyanate to obtain crystals of ammonium thiocyanate, the purity of which can reach 99%. The multi-effect concentration temperature is 65° C., and the concentration of the concentrated solution is 95 wt%. The thermal separation temperature of ammonium sulfate is 50°C. The vacuum is -0.06Mpa. The separation temperature of ammonium thiocyanate is 50°C, the degree of vacuum is 0.1Mpa, and it crystallizes at room temperature.

Embodiment 3

[0035] After the coke oven gas desulfurization and decyanation wastewater is decolorized, part of the organic and mechanical impurities are removed, ammonium persulfate is added to react with ammonium thiosulfate in the wastewater, and ammonium thiosulfate is oxidized with ammonium persulfate to generate sulfur, ammonium bisulfate, Sulfur is removed, ammonia water is added to convert ammonium bisulfate into ammonium sulfate, and the waste water is changed from a three-component mixture of ammonium thiocyanate, ammonium thiosulfate and ammonium sulfate into a two-component mixture of ammonium thiocyanate and ammonium sulfate that is easy to crystallize and separate Parts of the mixed solution, followed by multi-effect concentration, separation of ammonium sulfate while hot, and natural cooling of liquid ammonium thiocyanate to obtain crystals of ammonium thiocyanate, the purity of which can reach 99%. The multi-effect concentration temperature is 90° C., and the concentration of...

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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 utilizing coke oven gas desulfurization and decyanation wastewater, in particular to a method for directly utilizing 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 sulfides such as hydrogen sulfide, which enters the gas together with hydrogen cyanide, forming gas impurities. Coke oven gas generally contains hydrogen sulfide 5-8g / m 3 , hydrogen cyanide 1-2.5g / m 3 . Hydrogen sulfide and hydrogen cyanide are highly corrosive and toxic, causing strong corrosion to production equipment and pipelines, and can also cause poisoning and deactivation of synthetic gas chemical reaction catalysts, seriously affecting the yield and quality of the final product. [0003] For this reason, after the mixed gas is generated, ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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