A kind of chlorine dioxide preparation method of recyclable sodium acid sulfate

Abstract

The present invention discloses a chlorine dioxide preparation method capable of recycling sodium acid sulfate. According to the method, firstly, a sodium chlorate solution is filtered to be injected into a generator together with concentrated sulfuric acid to form a reaction mother liquor. Secondly, a mixed reducing agent composed of methanol and hydrogen peroxide is added, and then chlorine dioxide gas and a small amount of chlorine are generated after reaction. Thirdly, the chlorine dioxide gas is cooled and then is absorbed by the low-temperature chilled water to obtain a chlorine dioxide aqueous solution. During the continuous generation of chlorine dioxide, sodium acid sulfate crystals are generated at the same time as a by-product. After that, the sodium acid sulfate crystals are fed into an aqueous solution in a sodium sulfate converter reactor. The low-pressure steam is introduced to heat an obtained product and then the obtained product is stirred continuously. After the replacement reaction of sodium acid sulfate, a neutral sodium sulfate slurry is dehydrated through a sodium sulfate filtering machine. An obtained thickened suspension liquid is washed by the sodium sulfate filtering machine to obtain neutral sodium sulfate crystals finally. According to the technical scheme of the invention, the problem in the prior art that sodium acid sulfate, generated during the preparation of chlorine dioxide, is difficult to process and easily causes the secondary pollution can be solved. Meanwhile, the purpose of turning waste into wealth is realized. Moreover, the comprehensive utilization of resources is realized.

Description

technical field [0001] The invention relates to the field of chlorine dioxide production, in particular to a method for preparing chlorine dioxide from which sodium acid sulfate can be recovered. technical background [0002] Chlorine dioxide is a strong oxidizing agent. Stable chlorine dioxide has been considered by the World Health Organization as a fungicide with good effect and a bactericidal disinfectant with excellent performance, and it is also a good paper bleaching agent. Since the 1930s, industrial production has begun, and there are currently about 1,000 chlorine dioxide production plants in North America and Europe. The preparation methods of chlorine dioxide are mainly divided into two categories: electrolytic method and chemical method. The electrolysis method is to directly react the sodium chlorate obtained by the electrolysis of salt water with hydrochloric acid in the device to generate chlorine dioxide. Since the 1970s, a new method of electrolytically s...

AI Technical Summary

Problems solved by technology

Since the 1970s, a new method of electrolytically synthesizing chlorine dioxide with sodium chloride, sodium chlorate and sodium chlorite has been developed successively. This method requires a large investment in equipment and complicated processes, and has not yet been widely promoted.

Since the 1970s, foreign countries have successively developed a new method of electrolytically synthesizing chlorine dioxide using sodium chloride, sodium chlorate and sodium chlorite as electrolytes. This method requires a large investment in equipment and complicated processes, and has not yet been promoted.

The easiest method to achieve is acid-base neutralization, but it is an irreversible trend to replace chlorine gas with chlorine dioxide at present, so more and more acid sodium sulfate needs to be neutralized, resulting in sodium hydroxide and sodium hydroxide in the chlor-alkali plant chlorine imbalance

Sodium hydroxide usage increases while chlorine usage decreases, resulting in higher production costs

In addition, because the acid of sodium bisulfate is neutralized, sulfuric acid must be continuously replenished to the chlorine dioxide generator to maintain the required acidity, which further increases the production cost

For kraft pulping enterprises, the sodium acid sulfate can be sent to the alkali recovery workshop for recycling in principle, but in the actual application process, evaporator fouling and black liquor spray gun nozzle blockage often occur; and for alkali French pulping enterprises, sodium acid sulfate has no recycling value

Therefore, many companies choose to discharge directly, which not only pollutes the environment, but also wastes chemical resources