System and method for high-salt wastewater grading crystallization treatment

Abstract

The invention discloses a system and a method for high-salt wastewater grading crystallization treatment. The system comprises an adjusting tank, a first sodium chloride evaporative crystallization system, a sodium chloride mother liquor buffer tank, a potassium nitrate freezing crystallization system, a second sodium chloride evaporative crystallization system and a miscellaneous salt evaporativecrystallization system. The method comprises the following steps: (1) homogenizing and averaging treatment of wastewater; (2) primary evaporative crystallization of sodium chloride; (3) addition of potassium chloride into a sodium chloride mother liquor to obtain a mixed solution; (4) freezing to separate out potassium nitrate; and (5) evaporative crystallization of a potassium nitrate frozen mother liquor. The method has the advantages of low wastewater treatment cost, multiple product types and small impurity salt amount, the purity of produced sodium chloride is greater than 99%, the purity of sodium sulfate is greater than 99%, the purity of potassium nitrate is greater than 99%, and the yield of impurity salt is less than or equal to 10%.

Description

Technical field: [0001] The invention relates to the field of water treatment, in particular to a high-salt wastewater fractionation and crystallization treatment system and method. Background technique: [0002] The high-salt waste water of the present invention is waste water produced in coal mines, chemical industry, coal chemical industry, power plants, metallurgy, pharmaceuticals and other industries, mainly production circulating water, sewage discharge, domestic sewage in factory areas, etc., and the main components are sodium chloride, sulfuric acid Sodium and sodium nitrate, also contains calcium magnesium, silicon dioxide, refractory organic matter, etc. [0003] At present, with the advancement of science and technology and the development of the times, the country's environmental protection requirements for all walks of life are becoming increasingly stringent, and it is strictly forbidden to secretly bury and discharge. And this is a severe test for enterprises...

AI Technical Summary

Problems solved by technology

Although most of the waste water can be reused and the fractional crystallization of sodium chloride and sodium sulfate can be achieved after these processes are processed, these processes are unstable, and the output of sodium chloride and sodium sulfate is less, and the purity is lower than 98%. The whiteness is not up to standard, so it cannot be used as a resource; at the same time, due to the high content of sodium nitrate in the water, the output rate of waste water miscellaneous salts is as high as 25%.

[0005] To sum up, although the existing technology can realize the reuse of most of the waste water and separate crystallization of sodium chloride and sodium sulfate, there are problems of unstable operation, high salt yield of miscellaneous salts, low yield of crystallized salt, poor quality, and inability to recycle resources. issues such as utilization

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