Separate crystallization method for extracting recyclable high-purity sodium sulfate and sodium chloride from high-salinity wastewater

A technology for high-salt wastewater and sodium chloride, which is applied in chemical instruments and methods, alkali metal chloride, alkali metal sulfite/sulfate dehydration, etc., can solve the problem of high operating pressure, high operation and maintenance costs of nanofiltration membranes, Membrane short service life and other issues, to achieve good economic and social benefits, ease the pressure on enterprises, high process stability

Active Publication Date: 2018-04-03
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method needs to first use sodium filtration membrane for salt separation, which increases the cost of membrane materials; at the same time, the operating pressure of nanofiltration membrane is high, and the requirements for membrane endurance and anti-fouling performance are very high, and the membrane service life is short. , high operation and maintenance costs

Method used

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  • Separate crystallization method for extracting recyclable high-purity sodium sulfate and sodium chloride from high-salinity wastewater
  • Separate crystallization method for extracting recyclable high-purity sodium sulfate and sodium chloride from high-salinity wastewater
  • Separate crystallization method for extracting recyclable high-purity sodium sulfate and sodium chloride from high-salinity wastewater

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The mass flow rate of high-salt wastewater fed by a coal chemical enterprise is 1000kg / h. After analysis, the mass fraction of sodium chloride is 2.28%, the mass fraction of sodium sulfate is 0.72%, and the COD value is 500mg / L.

[0031] 1. Pretreatment of high-salt wastewater, using activated carbon for decolorization pretreatment, the amount of activated carbon added is 7g / L wastewater, the COD removal rate is 75%, and insoluble impurities, Ca 2+ , Mg 2+ , silicate and other soluble substances;

[0032]2. The pretreated high-salt wastewater feed wastewater is first concentrated by electrodialysis, and the mass flow rate of the separated water is 833.33kg / h, and then concentrated by a mechanical vapor recompression (MVR) device, and the mass flow rate of the separated water is 55.90kg / h, the mass fraction of sodium chloride after twice concentration is 20.58%, and the mass fraction of sodium sulfate is 6.5%;

[0033] 3. Send the concentrated solution to the crystalli...

Embodiment 2

[0049] The mass flow rate of high-salt wastewater fed by a coal chemical enterprise is 1000kg / h. After analysis, the mass fraction of sodium chloride is 7.61%, the mass fraction of sodium sulfate is 2.38%, and the COD value is 580mg / L.

[0050] 1. Pretreatment of high-salt wastewater, using activated carbon for decolorization pretreatment, the amount of activated carbon added is 8g / L wastewater, the COD removal rate is 80%, and insoluble impurities, Ca 2+ , Mg 2+ , silicate and other soluble substances;

[0051] 2. The pretreated high-salt wastewater feed wastewater is first concentrated by electrodialysis, and the mass flow rate of the separated water is 444.44kg / h, and then concentrated by a mechanical vapor recompression (MVR) device, and the mass flow rate of the separated water is 185.78kg / h, the mass fraction of sodium chloride after twice concentration is 20.1%, and the mass fraction of sodium sulfate is 6.33%;

[0052] 3. The concentrated solution is sent to the crys...

Embodiment 3

[0060] The mass flow rate of high-salt wastewater fed by a coal chemical enterprise is 1000kg / h. After analysis, the mass fraction of sodium chloride is 3.10%, the mass fraction of sodium sulfate is 1.80%, and the COD value is 600mg / L.

[0061] 1. Pretreatment of high-salt wastewater, using activated carbon for decolorization pretreatment, the amount of activated carbon added is 9g / L wastewater, the COD removal rate is 85%, and insoluble impurities, Ca 2+ , Mg2+, silicate and other soluble substances;

[0062] 2. The pretreated high-salt wastewater feed wastewater is first concentrated by electrodialysis, and the mass flow rate of the separated water is 750.00kg / h, and then concentrated by a mechanical vapor recompression (MVR) device, and the mass flow rate of the separated water is 50.00kg / h, after concentration, the mass fraction of sodium chloride is 15.5%, and the mass fraction of sodium sulfate is 9.0%;

[0063] 3. The concentrated solution was sent to the crystallizer,...

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Abstract

The invention relates to a separate crystallization method for extracting recyclable high-purity sodium sulfate and sodium chloride from high-salinity wastewater. Activated carbon is adopted for decolorization pretreatment, the COD can be significantly reduced, and insoluble impurities and soluble substances such as Ca<2+>, Mg<2+>, silicate and the like can be removed simultaneously; after pretreatment, the wastewater is sent to electrodialysis and mechanical steam recompression devices sequentially for concentration, and sodium sulfate and sodium chloride are approximately saturated through concentration according to the initial composition of sodium sulfate and sodium chloride in the wastewater; the concentrated wastewater is sent to a crystallizer, sodium sulfate is obtained cooling crystallization, directly extracted, washed and dried, and an anhydrous sodium sulfate product is obtained; a concentrated solution of denitration mother liquor is subjected to two-stage evaporative crystallization, and the sodium chloride product is directly extracted, washed and dried; part of mother liquor obtained after two-stage evaporation salt removal returns to the system and is mixed with fed wastewater to be recycled, the rest mother liquor is sent to a mixed salt evaporative crystallizer. The sodium sulfate and sodium chloride products reaching the national standard are obtained.

Description

technical field [0001] The invention relates to a fractional crystallization method of high-salt wastewater, which is a fractional crystallization method of high-salt wastewater containing sodium sulfate and sodium chloride, and particularly relates to the extraction of high-purity sulfuric acid from high-salt wastewater that can be recycled and utilized The method for fractional crystallization of sodium and sodium chloride belongs to the field of environmental protection and chemical industry. Background technique [0002] High-salt wastewater comes from a wide range of sources, mainly concentrated in industries such as coal, electric power, oil refining, chemical industry, metallurgy, papermaking, and pesticides. With the development of modern industrial technology, the amount of high-salt wastewater is increasing rapidly, which brings great challenges to the current wastewater treatment and recycling technology. High-salt wastewater contains a variety of substances, inc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01D3/06C01D5/18C02F9/10C02F101/10C02F101/14C02F101/16
CPCC01D3/06C01D5/18C01P2006/80C02F1/04C02F1/4693C02F9/00C02F2101/101C02F2101/14C02F2101/16
Inventor 郝红勋卢海娇苏楠楠尹秋响谢闯王召侯宝红黄欣王永莉鲍颖
Owner TIANJIN UNIV
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