A method for recycling coke oven gas desulfurization and decyanation waste liquid by vacuum potassium carbonate method

Abstract

The invention discloses a vacuum potassium carbonate method for utilizing coke oven coal gas desulphurization and decyanation waste liquid recycling as a resource. The method is also suitable to be used in other waste liquids containing high concentration cyanide and sulfide. According to the method, cyanide and sulfide are simultaneously precipitated; the precipitate is separated by centrifugation; the waste liquid processed from desulphurization and decyanation is processed through pH regulation and coagulant dosing; the processed waste liquid is discharged into a carbonization wastewater biochemical treatment system, and is treated; ferrocyanide precipitate is subject to a reaction with added lye in a high temperature, and is converted into potassium ferrocyanide; potassium ferrocyanide is disoluted, and is separated by centrifugation, such that potassium ferrocyanide mother liquor is obtained; potassium ferrocyanide mother liquor is cooled and crystallized, such that potassium ferrocyanide product is obtained. The method has advantages of simple equipment and convenient operation. With the method, simultaneous desulphurization and decyanation can be realized, requirements of subsequent treatments are satisfied, the wastes are utilized as resources, and economic benefits are brought in.

Description

technical field [0001] The invention belongs to the field of waste recycling and treatment, in particular to a method for recycling coke oven gas desulfurization and decyanation waste liquid by vacuum potassium carbonate method. Background technique [0002] The vacuum potassium carbonate method coke oven gas desulfurization and decyanation process belongs to the wet absorption desulfurization process. The main process is to use potassium carbonate solution to directly absorb hydrogen sulfide and hydrogen cyanide in the gas; the rich liquid that has absorbed the acid gas enters the regeneration tower for regeneration, and the water vapor rising from the bottom of the regeneration tower contacts under vacuum and low temperature conditions, and the acid gas Desorbed from the rich liquid; the resulting acid gas can be used to produce elemental sulfur by the Claus process or sulfuric acid by the contact process. In the process of desulfurization and decyanation of coke oven gas...

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Problems solved by technology

For example, in the Chinese patent No. 200610043520.6, the inventor mentioned an electrolytic coagulation device that converts elemental iron into Fe 2+ , using Fe 2+ and S in phenol cyanide wastewater 2- and CN - The method of generating precipitation to remove the above two toxic substances is only suitable for the treatment of low-concentration cyanide and sulfide. When the concentration is high, not only the power consumption is huge, the iron electrode is replaced frequently, but also a large amount of sludge is generated, resulting in secondary Pollution; the invention patent with the patent number CA85100375A mentions a method of using soluble ferrous salt to first precipitate sulfide, then precipitate cyanide, and then treat the resulting "coarse white pulp" (a mixture of ferrocyanide) with acid to remove impurities Obtain the method for iron blue product afterward, this method has its limitation for the high waste liquid of sulfide content, because cyanide and sulfide content are all higher, have difficulty in precipitating sulfide and cyanide respectively by two steps, and produce by adding The treatment of acidic wastewater containing a large amount of sulfides produced by acid removal of impurities is also a big problem

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