Method for producing hydrogen chloride and sodium hydrogen sulfate crystals by taking rock salt as raw material

Abstract

The invention discloses a method for producing hydrogen chloride and sodium hydrogen sulfate crystals by taking rock salt as the raw material, which comprises the following steps that: the mixture of sodium sulfate and sodium chloride, i.e. rock salt and sulfuric acid react to produce the hydrogen chloride and sodium hydrogen sulfate crystals; first, under a stirring condition, according to a certain stoichiometric ratio, sulfuric acid and rock salt are intermittently added into a glass lining reaction vessel to react while the temperature is insulated; and then sodium bisulfate solution which contains sulfuric acid is introduced to a crystal tower which contains an appropriate amount of water from the bottom of the reaction vessel to be cooled, crystallized and vacuum filter step by step, and then is washed by saturated sodium bisulfate solution to prepare sodium bisulfate crystals; and finally, the high-concentration sulfuric acid is added into the filtrate to be mixed to be sulfuric acid with the initial reaction concentration, and recycled. The method of the invention not only makes full use of natural resources, but also improves the added value of the rock salt, does not discharge any waste liquid, and meets the requirements of sustainable development.

Description

technical field [0001] The invention relates to a production method of hydrogen chloride and bisulfate, in particular to a method for producing hydrogen chloride and sodium bisulfate crystals from rock salt. Background technique [0002] Hydrogen chloride gas is an important chemical raw material. With the increasing development of science and technology, fine chemical industries such as dyes, chloromethyl ether, anhydrous piperazine, cystine and pesticides, pharmaceutical intermediates and chlorinated polymers are more sensitive to hydrogen chloride. The demand is increasing. There are a lot of low-concentration hydrochloric acid discarded after pickling steel in iron and steel enterprises. Therefore, low-concentration hydrochloric acid can be used to absorb hydrogen chloride gas to increase the concentration, so that the discarded low-concentration hydrochloric acid can be recycled, thereby reducing the production cost and environmental treatment costs of steel enterprises...

AI Technical Summary

Problems solved by technology

Concentrated acid high-temperature method is to add concentrated sulfuric acid and potassium chloride into a high-temperature reaction kettle (250°C) to remove hydrogen chloride above the melting point of bisulfate. ammonium potassium fertilizer intermediate, and the by-product hydrogen chloride is a high-temperature corrosive gas containing dust, and the post-processing device is complicated

The dilute acid low temperature method is to use 60-75% dilute sulfuric acid and chloride to strip hydrogen chloride with water vapor at about 120°C to generate a bisulfate aqueous solution containing excess sulfuric acid. Compared with the high temperature method, the operating temperature is low and the investment is relatively low. , but, the reaction time is longer (2-5h), the energy consumption is still higher, and the bisulfate aqueous solution of generation is because solution concentration is thinner, and chlorine content is higher, therefore, in order to reach the chlorine content requirement of direct use, It is bound to introduce a large amount of steam in the later stage of the reaction to remove residual hydrogen chloride, thereby increasing the cost

Concentrated acid low-temperature method is to prepare a phase-transfer dispersion medium aqueous solution composed of excess sulfuric acid and corresponding bisulfate in a reaction kettle, add measured chlorides into the reaction kettle under stirring conditions, heat up to boiling, and then add to the reaction Gradually add sulfuric acid equivalent to the chloride in the kettle, after the sulfuric acid is added, keep warm for 30-35 minutes, then cool to normal temperature, filter the crystalline bisulfate and wash with water to obtain the finished product bisulfate, and recycle the mother liquor. The operability in production is enhanced compared with the previous two types of methods, but there are following problems: the feeding and reaction operation process is relatively complicated; in this method, water is used to wash the bisulfate product, resulting in product dissolution loss, and pressure filtration or suction filtration The final salt is easy to harden and absorb water, which is not conducive to transfer and packaging

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