Method for producing sodium thiosulfate

Abstract

The invention relates to an improved process for producing sodium thiosulfate in the field of the chemical industry. The improved process uses alkali waste water deoxidized by an aromatic nitro compound sodium sulfide as a raw material and comprises the process steps of sulfur oxidization, introduction of sulfur dioxide into the alkali waste water, heat filtration, sulfur treatment, concentration,active carbon decoloration, filtration, crystallization and separation. The improved process is characterized in that the technological processes of the sulfur oxidization and the introduction of sulfur dioxide into the alkali waste water comprise the following steps: crushing solid sulfurs and then inputting the crushed sulfur into a combustion furnace; introducing air into the furnace so as toensure that the sulfur powder is oxidized into a sulfur dioxide gas; imputing the sulfur dioxide gas into a reaction kettle to react with sodium hydrate and sodium sulfide in the alkali waste water soas to generate sodium sulfite; and then obtaining the finished product of the sodium thiosulfate through the process steps of the heat filtration, the sulfur treatment, the concentration, the decoloration, the filtration, the crystallization and the separation. The process saves energy resources and reduces the cost.

Description

technical field [0001] The invention relates to a production method of an inorganic compound, in particular to an improved production method of sodium thiosulfate. Background technique [0002] Sodium thiosulfate, commonly known as baking soda, is widely used in photography, tanning, papermaking, textile and other industries, as well as in the synthesis of pesticides and dyes. [0003] In the prior art, the production method of sodium thiosulfate mostly adopts the method of reclaiming from waste liquid commercially, for example: from the production wastewater of sulfur black or other sulfur dyes by filtration, active carbon decolorization, filtrate concentration, crystallization, The sodium thiosulfate pentahydrate with a purity of about 96% is recovered by centrifugal separation. For another example, using the alkaline waste water reduced by the aromatic nitro compound alkali sulfide as raw material, the purity is 96% to be obtained by adding sulfur, oxidation, filtration,...

AI Technical Summary

Problems solved by technology

[0004] In the traditional sulfur oxidation process of alkaline wastewater, Na 2 S, NaOH and S and O 2 The reaction is an exothermic reaction, the water is evaporated, and the liquid concentration rises, which is not conducive to the oxidation of the material. It is necessary to continuously add cold water to reduce the concentration, which is conducive to the reaction toward the reactant Na 2 S 2 o 3 However, due to the addition of a large amount of cold water, the concentration of the product is reduced, which increases the evaporation during the concentration process, increases the consumption of steam and electricity, and increases the cost

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