Method and apparatus for reducing cyanogen content of coking wastewater

Abstract

The invention relates to a method and an apparatus for reducing the cyanogen content of coking wastewater. The apparatus comprises a regenerating tower, a circulating ammonia pump, a raw material ammonia water pipeline, an alkali tank, a 42% alkali pump and a 2.5-5% alkali pump; the regenerating tower is connected with a desulphurization lean solution pump, the outlet of the desulphurization lean solution pump is connected with the circulating ammonia water pump, and the circulating ammonia water pump is connected with a coke oven; one end of the raw material ammonia water pipeline is connected with the raw material ammonia water pump, the other end of the raw material ammonia water pipeline is connected with the alkali washing section of a desulfurization tower, and the raw material ammonia water pipeline is connected with the 42% alkali pump; and the bottom of the alkali washing section of the desulfurization tower is connected with the alkali tank, and the alkali tank is respectively connected with an ammonia distiller and the alkali washing section of the desulfurization tower through the 2.5-5% alkali pump. Raw material ammonia water substitutes distilled ammonia wastewater and is mixed with a concentrated alkali, and the obtained mixture is sent to the alkali washing section of the desulfurization tower in order to remove hydrogen sulfide and hydrogen cyanide. The stability of the ammonia water volume of the alkali washing section is guaranteed; and the ammonia content of the raw material ammonia water is high, so the raw material ammonia water has a better desulphurization effect than the distilled ammonia wastewater.

Description

technical field [0001] The invention relates to a method and a device for reducing cyanide content in coking wastewater. Background technique [0002] The existing environmental protection process in the recovery operation area includes the recovery desulfurization section and the acid production section, but the cyanide content in the drainage outside the environmental protection process has not been able to meet the national index requirements of ≤0.2mg / L. Especially after the start-up of the recycling desulfurization section, since the vacuum potassium carbonate desulfurization process is adopted, the process needs to continuously discharge cyanide-containing waste liquid to the ammonia water system, and the vacuum condensate discharged outside is 7m 3 / h, the desulfurization lean liquid discharged outside is 200kg / h. After testing, the discharged waste liquid contains 3000mg / L of cyanide, resulting in the cyanide content of the ammonia distillation wastewater usually flu...

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Problems solved by technology

[0002] The existing environmental protection process in the recovery operation area includes the recovery desulfurization section and the acid production section, but the cyanide content in the drainage outside the environmental protection process has never reached the national index requirement of ≤0.2mg / L

Especially after the start-up of the recycling desulfurization section, since the vacuum potassium carbonate desulfurization process is adopted, the process needs to continuously discharge cyanide-containing waste liquid to the ammonia water system, and the vacuum condensate discharged outside is 7m 3 / h, the desulfurization lean liquid discharged outside is 200kg / h. After testing, the discharged waste liquid contains 3000mg / L of cyanide, resulting in the cyanide content of the ammonia distillation wastewater usually fluctuating between 200mg / L and 900mg / L, and the discharge of the environmental protection process contains cyanide Usually between 8mg / L and 20mg / L, even if the cyanide-reducing agent is added to the Fenton device, it will not be able to make the cyanide content of the external drainage reach the national standard of ≤0.2mg / L

In this regard, domestic counterparts generally adopt the method of adding desulfurization waste liquid pretreatment devices in the desulfurization section, with a one-time investment of 6 million yuan, desulfurization waste liquid treatment cost is 60 yuan / ton, and desulfurization waste liquid pretreatment device operating costs 360 RMB 10,000 per year, the desulfurization waste liquid discharged after treatment contains cyanide 200mg / L, and the ammonia distillation wastewater contains cyanide 30mg / L~50mg / L. Not only the one-time investment and operation costs are high, but the construction period is long, and the ammonia distillation wastewater contains cyanide still high

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