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A method for separating mixed waste salt containing sodium sulfate and sodium chloride

A separation method and sodium chloride technology, applied in chemical instruments and methods, alkali metal sulfite/sulfite, alkali metal sulfite/sulfate purification, etc., can solve the problem of poor economy, increased burden, and energy consumption Advanced problems, to achieve the effect of high recovery rate, low cost and simple operation

Active Publication Date: 2022-03-11
INST OF PROCESS ENG CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The high-salt wastewater is directly evaporated and crystallized by using an evaporation crystallization device to obtain mixed salts of sodium sulfate and sodium chloride. Impurities such as organic matter and heavy metals in the high-salt wastewater are also precipitated with the mixed salt. This method cannot solve the problem of harmlessness and Recycling, on the contrary, increases the new burden; the salt and nitrate co-production method evaporates sodium chloride and sodium sulfate at high temperature to obtain sodium sulfate and sodium chloride products, which consumes a lot of energy, and the evaporation process indicators are difficult to control; freezing Sodium sulfate decahydrate is obtained by denitration method, sodium sulfate decahydrate is dissolved and evaporated to obtain sodium sulfate decahydrate, and the mother liquor containing a large amount of sodium chloride is electrolyzed to produce caustic soda. This method has problems such as high energy consumption, large investment and poor economy; nanofiltration membrane method uses The high interception rate of the sulfate ion by the nanofiltration membrane makes the mixed solution separated by the nanofiltration membrane to obtain the retentate with high sodium sulfate concentration and the permeate with high sodium chloride purity, but this method has very high requirements for the nanofiltration membrane. High, and the cleaning of subsequent nanofiltration membranes is relatively difficult

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  • A method for separating mixed waste salt containing sodium sulfate and sodium chloride

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Effect test

Embodiment 1

[0049] This embodiment provides a method for separating mixed waste salt containing sodium sulfate and sodium chloride, the separation method comprising the following steps:

[0050] (1) Mix the mixed waste salt and ethylene glycol once at a temperature of 20°C for 90 minutes, and obtain sodium sulfate crystals and the first mother liquor through the first solid-liquid separation;

[0051] Wherein, in the mixed waste salt, the mass ratio of sodium sulfate to sodium chloride is 5:1; the mass ratio of ethylene glycol to sodium chloride in the mixed waste salt is 9:1;

[0052] (2) The first mother liquor and ethanol in step (1) were mixed for a second time at a temperature of 40°C for 50 minutes, and sodium chloride crystals and the second mother liquor were obtained through the second solid-liquid separation;

[0053] Wherein, the mass ratio of ethanol and the first mother liquor is 2:1;

[0054] (3) Evaporating the second mother liquor in step (2) under reduced pressure at a t...

Embodiment 2

[0057] This embodiment provides a method for separating mixed waste salt containing sodium sulfate and sodium chloride, the separation method comprising the following steps:

[0058] (1) Mix the mixed waste salt and ethylene glycol at a temperature of 40°C for 50 minutes once, and obtain sodium sulfate crystals and the first mother liquor through the first solid-liquid separation;

[0059] Wherein, in the mixed waste salt, the mass ratio of sodium sulfate to sodium chloride is 1:1; the mass ratio of ethylene glycol to sodium chloride in the mixed waste salt is 12:1;

[0060] (2) The first mother liquor and ethanol in step (1) were mixed for a second time at a temperature of 20°C for 70 minutes, and sodium chloride crystals and the second mother liquor were obtained through the second solid-liquid separation;

[0061] Wherein, the mass ratio of ethanol and the first mother liquor is 4:1;

[0062] (3) Evaporating the second mother liquor in step (2) under reduced pressure at a ...

Embodiment 3

[0065] This embodiment provides a method for separating mixed waste salt containing sodium sulfate and sodium chloride, the separation method comprising the following steps:

[0066] (1) Mix the mixed waste salt and ethylene glycol at a temperature of 30°C for 70 minutes once, and obtain sodium sulfate crystals and the first mother liquor through the first solid-liquid separation;

[0067] Wherein, in the mixed waste salt, the mass ratio of sodium sulfate to sodium chloride is 2:1; the mass ratio of ethylene glycol to sodium chloride in the mixed waste salt is 10:1;

[0068] (2) The first mother liquor and ethanol in step (1) were mixed for a second time at a temperature of 30°C for 60 minutes, and sodium chloride crystals and the second mother liquor were obtained through the second solid-liquid separation;

[0069] Wherein, the mass ratio of ethanol and the first mother liquor is 3:1;

[0070] (3) Evaporate the second mother liquor in step (2) under reduced pressure at a te...

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Abstract

The invention provides a method for separating mixed waste salt containing sodium sulfate and sodium chloride. Since sodium sulfate is insoluble in ethylene glycol and sodium chloride is soluble in ethylene glycol and slightly soluble in ethanol, the present invention first utilizes sulfuric acid The difference in solubility of sodium and sodium chloride in ethylene glycol was separated to obtain sodium sulfate, and then the difference in solubility of sodium chloride in ethanol and ethylene glycol was used to separate and obtain sodium chloride. The operation is simple and no heating is required. Low cost; the obtained sodium sulfate crystals and sodium chloride crystals have high purity, and ethanol and ethylene glycol can be recycled, which is green and environmentally friendly; under optimal conditions, the obtained sodium sulfate crystals have a purity of ≥98%, meeting GB / T 6009 ‑2014 Class II first-class product requirements, the purity of the obtained sodium chloride crystals is ≥97.5%, which meets the requirements of GB / T 5462‑2015 Class II industrial dry salt, and the recovery rate of sodium is high.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a method for separating mixed waste salt containing sodium sulfate and sodium chloride. Background technique [0002] In industries such as coal chemical industry, hydrometallurgy, chlor-alkali, pharmaceuticals, and printing and dyeing, a large amount of high-salt wastewater containing sodium sulfate and sodium chloride will be produced during industrial production, and these wastewaters contain different concentrations of organic matter and heavy metals. thing. [0003] CN110040908A discloses a sodium chloride and sodium sulfate ultrasonic evaporation crystallization salt separation system, including mixed salt wastewater storage tank, adjustment tank, pretreatment device, ultrasonic evaporation crystallization device, condensation treatment device and salt separation device; in addition, Disclosed is a sodium chloride and sodium sulfate ultrasonic evaporation cryst...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B09B3/80C01D3/18C01D3/08C01D5/00C01D5/16
CPCC01D3/18C01D3/08C01D5/00C01D5/16C01P2006/80
Inventor 张洋张贺东范兵强申长帅郑诗礼曹宏斌陈沛松
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI