Freezing salt separation system and freezing salt separation method

Abstract

The invention discloses a freezing salt separation system and a freezing salt separation method. The freezing salt separation system comprises a precision pretreatment device, a first reverse osmosisdevice, an electrodialysis device, a carbon remover, a freezing crystallization device, a nanofiltration device, a sodium chloride evaporation crystallization device, an organic matter removal device,a second reverse osmosis device and a miscellaneous salt evaporation crystallization device, wherein the precision pretreatment device, the first reverse osmosis device, the electrodialysis device, the carbon remover, the freezing crystallization device, the nanofiltration device, the sodium chloride evaporative crystallization device and the carnallite evaporative crystallization device are connected in sequence; and the second reverse osmosis device and the organic matter removal device are sequentially connected with the electrodialysis device. The freezing salt separation system and method can achieve the purposes of being short in technological process, stable in operation, relatively mild in operation condition, low in investment cost, low in final miscellaneous salt rate and free of emission.

Description

technical field [0001] The invention relates to the field of environmental protection, in particular to a freezing salt separation system and a freezing salt separation method. Background technique [0002] At present, with the increasingly stringent environmental protection requirements, zero discharge of high-salt wastewater has become an inevitable requirement. In recent years, after a lot of exploration, people in the industry have gradually formed a process of nanofiltration + cold and hot salt separation and crystallization, and it has been verified in engineering practice that high-quality crystallized salt can be separated and obtained. However, there are problems in this method: one is that the nanofiltration system is huge, and the operating failure rate of the nanofiltration system increases. Moreover, the nanofiltration system has a good interception effect on sodium sulfate, and has almost no interception or even negative interception on sodium chloride, result...

AI Technical Summary

Problems solved by technology

However, there are problems with this method: first, the nanofiltration system is huge, and the operating failure rate of the nanofiltration system increases

Moreover, the nanofiltration system has a good interception effect on sodium sulfate, and has almost no interception or even negative interception on sodium chloride, resulting in the presence of sodium sulfate and sodium chloride on the nanofiltration concentrated water side. Therefore, the nanofiltration concentrated water needs to further adopt nanofiltration The overall system design is complicated, and the investment and operation costs are high; the second is that the current cold and hot method of salt separation and crystallization involves the alternate operation of freezing crystallization and evaporative crystallization, resulting in increased energy consumption and waste of materials. The conversion between high and low temperatures can easily cause crystallization and blockage of pipelines and equipment; third, in the current method, the nanofiltration product water and nanofiltration concentrated water are crystallized separately, and the crystallization system is difficult to control, resulting in a large output of miscellaneous salts in the system, which increases the follow-up process. Difficulty and cost of miscellaneous salt treatment

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