Waste water treatment method for paraquat synthesized through ammonia cyanidation process

Abstract

The invention discloses a waste water treatment method for paraquat synthesized through an ammonia cyanidation process. The method comprises the steps of steam stripping, chlorine oxidizing, decoloring and filtering and concentrating crystallization. In the specific process, firstly, collected waste water is subjected to steam stripping, chlorine is introduced, cyanogens ions in the paraquat waste water are damaged, meanwhile, reduced chloridions and ammonium group ions in the paraquat waste water are combined to generate ammonium chloride, then a screen mesh is used for filtering for decoloring, then the waste water is concentrated through double effect evaporation, ammonium chloride in the waste water is recycled, the remaining waste water is directly incinerated in an incinerator or used for a next batch of waste water to be evaporated till the concentration of cyanogens in ammonium chloride obtained after the current batch of waste water is cooled and crystallized is larger than 100 ppm or the content of sodions is larger than 1% (w / v), and the current batch of filtrate is incinerated. According to the method, resource utilization of the waste water is achieved, pollutants in the waste water are reduced, pollution to the environment is reduced, and meanwhile the treatment cost of the paraquat waste water is greatly reduced.

Description

technical field [0001] The invention relates to a wastewater treatment method for synthesizing paraquat by the cyanamide method. Background technique [0002] As the second largest herbicide pesticide in the world, paraquat’s domestic output is increasing every year. The method of synthesizing paraquat generally adopts the advanced ammonium cyanide method. The ammonium cyanide method has high yield, good product and process The advantage of easy control, but this method also produces a large amount of waste water, because the waste water contains cyanide ions and a large amount of ammonium chloride salt, and the waste water contains a part of ammonia, so the treatment is more difficult. [0003] At present, the method of first gas stripping and concentrating waste water, and then incinerating it is widely used at home and abroad. This method can effectively control the pollution of paraquat waste water from the ammonium cyanide method, but the operation cost of this method i...

AI Technical Summary

Problems solved by technology

[0002] As the second largest herbicide pesticide in the world, paraquat’s domestic output is increasing every year. The method of synthesizing paraquat generally adopts the advanced ammonium cyanide method. The ammonium cyanide method has high yield, good product and process The advantage of easy control, but this method also produces a large amount of waste water, because the waste water contains cyanide ions and a large amount of ammonium chloride salt, and the waste water contains a part of ammonia, so the treatment is more difficult

[0003] At present, the method of first gas stripping and concentrating waste water, and then incinerating it is widely used at home and abroad. This method can effectively control the pollution of paraquat waste water from the ammonium cyanide method, but the operation cost of this method is relatively high, and incineration needs to consume a large amount of heavy oil. The requirements of energy-consuming industrial development and high equipment costs are not conducive to the control of operating costs of enterprises

Some useful substances in wastewater cannot be recycled due to direct incineration, resulting in a waste of resources