Sulfuric acid recovery technique in process of producing cystine by adopting sulfuric acid method

Abstract

The invention discloses a sulfuric acid recovery technique in the process of producing cystine by adopting a sulfuric acid method. The sulfuric acid recovery technique comprises the steps of: (1) simultaneously flowing hydrolysate and water through an anion-exchange membrane diffusion dialyzer, controlling the flow velocity of the hydrolysate and water so that the pH value of the hydrolysate flowing out is 1-1.5 and the water flowing out becomes acid liquor; and (2) flowing the hydrolysate and water out to simultaneously flow through an electrodialyzer, so that the pH value of the hydrolysate flowing out from a desalting chamber of the electrodialyzer is 3-4 through controlling the electrified voltage and the flow rate of the hydrolysate and water, wherein the hydrolystae flows in cystine production procedure, and the water flowing out from a concentration chamber of the electrodialyzer becomes diluted acid liquor which is used for replacing the water in the step (1), thus realizing the recovery cycle of sulfuric acid. The technique is simple and easy for steps, the consumption of alkali and liquid ammonia in cystine production can be reduced, the raw materials can be saved, the production cost can be lowered, the content of salt in waste water can be decreased, and the treating difficulty and treatment cost of waste water can be lowered.

Description

Technical field [0001] The invention relates to a sulfuric acid recovery process in the process of producing cystine by a sulfuric acid method. Background technique [0002] The process of producing cystine by hydrolyzing hair with sulfuric acid generally includes the following processes: hydrolysis, primary neutralization, primary decolorization, secondary neutralization, secondary decolorization, tertiary neutralization and purification. After the hydrolysis is completed, the hydrolysate will be produced. Add alkali to the hydrolysate to neutralize the sulfuric acid. After the neutralization, cystine is precipitated. The crude cystine is obtained by filtration. The filtrate is further neutralized with sodium bicarbonate and filtered to obtain cystine. The second crude acid product, the filtrate is neutralized with liquid ammonia, and the third crude product of cystine is obtained by filtration. The filtrate can further extract chromic acid, and finally the salt-containing waste...

AI Technical Summary

Problems solved by technology

The hydrolyzate that will be produced after the hydrolysis is completed, adding alkali to the hydrolyzate to neutralize the sulfuric acid in it, the cystine is precipitated after neutralization, and the primary crude product of cystine is obtained by filtration, the filtrate is continued to be neutralized with sodium bicarbonate, and the cystine is obtained by filtration. The secondary crude product of chromic acid, the filtrate continues to be neutralized with liquid ammonia, and the tertiary crude product of cystine is obtained by filtration. The filtrate can further extract chromic acid, and finally the salty waste liquid enters the sewage treatment equipment for treatment. Alkali and liquid ammonia will produce a large amount of salt, which not only increases the difficulty of sewage treatment, but also prevents the excess sulfuric acid in the hydrolyzate from being effectively utilized

The above treatment methods lead to low utilization rate of raw materials, waste of raw materials and increased energy consumption, which directly lead to increased production costs