Method for extracting ammonium thiocyanate from ammonia-process desulfurization waste liquid by oxidation process

Abstract

The invention discloses a method for extracting ammonium thiocyanate from ammonia-process desulfurization waste liquid by an oxidation process, and belongs to the technical field of treatment of the desulfurization waste liquid. According to the method, an oxidation reaction is implemented by a way of blowing air or oxygen into ammonia-process desulfurization waste liquid; by the oxidation reaction, ammonium thiosulfate in the desulfurization waste liquid is oxidized into ammonium sulfate, but ammonium thiocyanate is not oxidized and is still reserved in the desulfurization waste liquid; and the ammonium thiocyanate is extracted by ways of evaporation and secondary crystallization. The method disclosed by the invention is applicable to the treatment of the desulfurization waste liquid which is generated from the process of desulfurization and decyanation of the gas by a catalytic oxidation process, and is suitable for the waste liquid treatment in the field of desulfurization process of hydrogen sulfide-containing gases such as coke oven gas, natural gas, coal-bed methane and refinery gas. By the method, the ammonium thiosulfate salt in the waste liquid is converted into the ammonium sulfate salt and the ammonium thiocyanate salt is protected, and the ammonium thiosulfate salt and the ammonium thiocyanate salt are separated from the waste liquid and purified into products.

Description

technical field [0001] The invention belongs to the technical field of desulfurization waste liquid treatment, in particular to a method for extracting ammonium thiocyanate from ammonia desulfurization waste liquid by oxidation. Background technique [0002] The catalytic oxidation desulfurization process using ammonia as the alkali source will inevitably produce desulfurization waste liquid. For a long time, the domestic desulfurization process has no supporting design, and most of the waste liquid produced is consumed by remixing coking coal or being used for wet coke quenching. Coke equipment corrosion, gas desulfurization costs increase, and gas system equipment corrosion rate rises. The existing waste liquid treatment devices basically adopt fractional crystallization physical process, which is not easy to extract high-purity qualified products at one time. The reason is that there are many sulfur compounds and salts in the waste liquid. Ammonium sulfate, ammonium thi...

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Problems solved by technology

The oxidation efficiency of the Herohax process is very high, and useful products can be obtained, which can increase the yield of ammonium sulfate. However, this process method requires the equipment to be made of titanium alloy stainless steel corrosion-resistant materials. Due to the high cost of materials, the process construction cost is high. The maintenance cost of equipment is also expensive, so this technology has been introduced into China for nearly 30 years, but it has not been accepted by domestic coking manufacturers. Destroyed, producing a product of low value-added ammonium sulfate

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