Device and process for separating sodium chloride salt and sodium sulfate salt in coal chemical industry high-salinity wastewater

Abstract

The invention discloses a device and a process for separating sodium chloride salt and sodium sulfate salt in coal chemical industry high-salinity wastewater. The device comprises an ozone catalytic oxidation device, a high-density silicon removal unit, a multi-medium filter, an ultrafiltration device, a nanofiltration unit, a DTRO unit, a high-pressure reverse osmosis unit, an evaporative crystallization device, a freezing crystallization unit, a heavy metal remover and the like. According to the technical scheme, a catalytic ozonation technology is adopted to treat high-content COD in high-efficiency reverse osmosis strong brine, and meanwhile, a high-density silicon removal technology is adopted to remove silicon ions in salt-containing wastewater, so that the stability of subsequent membrane concentration and crystallization operation is guaranteed, and the purity of sodium sulfate and sodium chloride products is also improved; a nanofiltration technology and a high-pressure reverse osmosis technology are adopted, so that the purity and the concentration of sodium chloride are greatly improved, and the energy consumption of an evaporative crystallization device is reduced; meanwhile, the recovery rate of the sodium chloride salt is also improved, and guarantee is provided for industrial use.

Description

technical field [0001] The invention belongs to the field of waste water desalination, in particular to a separation device and process for sodium chloride salt and sodium sulfate salt in high-salt waste water of coal chemical industry. Background technique [0002] In recent years, the problem of environmental pollution in my country has become increasingly prominent, and the trend of ecological environment damage has not been effectively controlled. Therefore, the country will adopt stricter environmental protection standards and regulatory measures. The new coal chemical industry consumes a lot of water, and the annual water consumption is usually as high as tens of millions of cubic meters or even higher. The rapid development of coal chemical industry has caused the imbalance of regional water resources. Therefore, it is imperative to strengthen the desalination treatment of coal chemical wastewater and strengthen the reuse of wastewater. However, in the field of coal ...

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Problems solved by technology

Taking the zero discharge of coal chemical wastewater as an example, in the currently operating mixed salt evaporation and crystallization device, the discharge of mother liquor can reach 15-18% of the water volume of evaporated raw materials. These mother liquors have no way out, except for some projects that are spray-dried into waste salt. Most are intractable and become a headache

At the same time, due to the unreasonable treatment process, in the process of concentration and evaporative crystallization of salty wastewater, organic matter and scaling ions will cause foaming, boiling point increase, scaling and equipment failure during the concentration of wastewater and evaporative crystallization. Corrosion, making it difficult to run the concentration and evaporation crystallization process stably for a long period of time

In a project in Inner Mongolia, due to the poor separation of organic matter in the process of zero discharge, the stable operation of the terminal crystallization process is difficult to be guaranteed, and the water quality of the recovered condensate is difficult to meet the standard, and the output crystallized salt is brown

Due to the low concentration of sodium sulfate in the freezing operation of a project in Xinjiang, the sodium sulfate did not reach the crystallization temperature at the design temperature during the freezing process, and the salt components were not separated. If this situation is not effectively improved, it will have an impact on the environment. It will also seriously affect the economic benefits of the factory

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