Zero-discharge salt separation purification method for industrial high-salt wastewater

A technology of high-salt wastewater and purification methods, applied in the chemical industry, chemical instruments and methods, alkali metal sulfite/sulfite, etc., can solve the problems of high impurities in coarse salt, non-recyclable, high operating costs, etc., to achieve High purity, low investment and operating costs

Active Publication Date: 2017-03-22
济宁璟华环保科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the investment and operating costs of multi-effect evaporation and crystallization are very high, and the coarse salt obta

Method used

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  • Zero-discharge salt separation purification method for industrial high-salt wastewater
  • Zero-discharge salt separation purification method for industrial high-salt wastewater
  • Zero-discharge salt separation purification method for industrial high-salt wastewater

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0031] Example 1

[0032] The first step, freezing and recovering sodium sulfate

[0033] After the wastewater is concentrated and treated by the membrane, the discharged concentrated brine enters the freezer, and the temperature is controlled to 1°C to cool down and precipitate sodium sulfate;

[0034] The second step, evaporation

[0035] After the concentrated brine is frozen to separate sodium sulfate, it exchanges heat with distilled water in a plate heat exchanger. After the heat exchange, the temperature is raised to 91°C, and then enters the steam preheater. After preheating, the temperature reaches 100°C. The suction port of the pump is sent to the MVR falling film evaporator, and evenly enters the tube side of the MVR falling film heat exchanger through the liquid distributor, and exchanges heat with the secondary steam from the compressor to make it evaporate, and the concentration of sodium chloride salt is concentrated to 25%;

[0036] The third step, crystalli...

Example Embodiment

[0040] Example 2

[0041] The first step, freezing and recovering sodium sulfate

[0042] After the wastewater is concentrated and treated by the membrane, the discharged concentrated brine enters the freezer, and the temperature is controlled to 3°C to cool down and precipitate sodium sulfate;

[0043] The second step, evaporation

[0044] After the concentrated brine is frozen to separate sodium sulfate, it exchanges heat with distilled water in a plate heat exchanger. After the heat exchange, the temperature is raised to 96°C, and then enters the steam preheater. After preheating, the temperature reaches 105°C. The suction port of the pump is sent to the MVR falling film evaporator, and evenly enters the tube side of the MVR falling film heat exchanger through the liquid distributor, and exchanges heat with the secondary steam from the compressor to make it evaporate, and the concentration of sodium chloride salt is concentrated to 25%;

[0045] The third step, crystalli...

Example Embodiment

[0049] Example 3

[0050] The first step, freezing and recovering sodium sulfate

[0051] After the wastewater is concentrated and treated by the membrane, the discharged concentrated brine enters the freezer, and the temperature is controlled to 1.2°C to cool down and precipitate sodium sulfate;

[0052] The second step, evaporation

[0053]After the concentrated brine is frozen to separate sodium sulfate, it exchanges heat with distilled water in a plate heat exchanger. After the heat exchange, the temperature is raised to 93°C, and then enters the steam preheater. After preheating, the temperature reaches 102°C. The suction port of the pump is sent to the MVR falling film evaporator, and evenly enters the tube side of the MVR falling film heat exchanger through the liquid distributor, and exchanges heat with the secondary steam from the compressor to make it evaporate, and the concentration of sodium chloride salt is concentrated to 26%;

[0054] The third step, crystall...

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Abstract

The invention belongs to the technical field of wastewater treatment, and discloses a zero-discharge salt separation and purification method for industrial high-salt wastewater. The zero-discharge salt separation and purification method for the industrial high-salt wastewater is mainly characterized by comprising the steps that sodium sulfate in concentrated saline water is recycled through a freezing method, and effluent enters an evaporator to make the concentration of the saline water further increased to 25%-30%; then the effluent enters a forced circulation crystallizer, when the content of solid in the crystallizer reaches 30%-35%, materials starts to be discharged into a cyclone hydraulic separator through a circulating pump, and preliminary solid-liquid separation is achieved; after separation is conducted, crystals containing a small amount of mother liquid enters a centrifugal machine, thorough solid-liquid separation is conducted, and the separated mother liquid directly enters a mother liquid tank. The technology has the advantages that the sodium sulfate and sodium chloride can be recycled; the equipment investment in the method is low, and the operating cost is low; salt can be fully separated and reused, externally discharged dangerous waste does not exist, zero discharge is achieved, energy conservation and environment protection are facilitated, and higher economic benefit and social benefit are achieved.

Description

technical field [0001] The invention belongs to the technical field of chemical wastewater treatment and salt purification, separation and reuse, and in particular relates to a method for purifying industrial high-salt wastewater with zero discharge and salt separation. Background technique [0002] Industrial high-salt wastewater comes from the membrane concentrate, and the calcium and magnesium ions and a small amount of heavy metal ions in the concentrate are basically removed in the lime soda softening section and ion exchange section in the membrane concentration process. Therefore, the discharged concentrated brine mainly contains sodium sulfate and sodium chloride salts. Among them, the sodium sulfate content is as high as 7%-13%, and the sodium chloride is 5%-8%. It cannot be removed by conventional membrane methods. [0003] At present, the multi-effect evaporation crystallization method commonly used in industrial water zero discharge technology can be applied to...

Claims

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Application Information

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IPC IPC(8): C02F9/10C01D5/00C01D3/06
CPCY02P20/10
Inventor 焦伟堂焦晗焦伟祥
Owner 济宁璟华环保科技有限公司
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