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Method of refining salt by membrane filtration

A technology for refined brine and membrane filtration, applied in chemical instruments and methods, membrane technology, semi-permeable membrane separation, etc., can solve problems such as large quality impact, unstable brine quality, and excessive brine, and reduce the number of backwash cleaning , The effect of ensuring high permeation flux and reducing processing load

Active Publication Date: 2006-11-29
JIANGSU JIUWU HITECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The main disadvantages of this process are: it is greatly affected by the quality of raw salt, the quality of brine is unstable, the SS in the filtered brine exceeds the standard, and the filter is easy to clog and fall off, etc.
The composite tubular filter membrane of PTEE membrane / PP used in this kind of process has the following problems: (1) the composite strength of the two materials is low; (2) the overlapping part of the filter membrane is easily broken; (4) Affected by the pretreatment effect, the filtration capacity changes too much
The existing terminal filtration brine refining method usually adopts CaCO 3 and Mg(OH) 2 The step-by-step separation method increases the process steps and occupies a large area

Method used

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  • Method of refining salt by membrane filtration
  • Method of refining salt by membrane filtration
  • Method of refining salt by membrane filtration

Examples

Experimental program
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Effect test

Embodiment 1

[0036] Below in conjunction with figure, the present invention is described in detail

[0037] A) Refined brine and impurity-rich brine from the evaporation section enter the brine storage tank, and enter the brine tank through the brine pump, and the brine dissolves the original salt to become saturated coarse brine, which overflows from the upper part of the brine tank to the reaction tank ;

[0038] B) metering into the reaction tank the refining agent NaOH, NaOH 2 CO 3 , BaCl 2 and other chemicals make the Ca in brine 2+ , Mg 2+ , SO 4 2- Wait for the reaction to generate Mg(OH) 2 , CaCO 3 with BaSO 4 and other solid substances, in which NaOH and Na 2 CO 3 Adding concentrations were greater than Ca 2+ with Mg 2+ Concentration 1-5%, BaCl 2 The added concentration is less than SO 4 2- Concentration 1-5%;

[0039] C) The above-mentioned brine enters the preprocessor, and the coagulation aiding agent sodium polyacrylate, polyacrylamide or causticized starch is...

Embodiment 2

[0042] After salting, the calcium content in the crude brine is 754.2mg / L, the magnesium content is 83.21mg / L, the sulfate content is 7.6g / L, and the SS content is 3589.33mg / L. Send this saturated brine into the reaction tank, add sodium hydroxide 0.4g / L, sodium carbonate 1.6g / L and barium chloride 12.5g / L to react, after the reaction is completed, enter the preprocessor, add polyacrylamide 50mg / L l and hydrogen peroxide 30mg / l, after adsorption and co-precipitation, pumped into the inorganic membrane cross-flow filter, using a ceramic membrane with a pore size of 0.02μm, 19 channels, the inner diameter of the channel is 4mm (no turbulence promoter is installed in the channel), cross-flow Speed ​​1m / s, operating pressure 0.4MPa, membrane permeation flux 0.5m 3 m -2 h -1 , the experiment was carried out for 5h without backflushing the membrane. The filtered brine was measured by ICP (plasma emission spectrometry), and calcium, magnesium and SS were not detected, and the sulf...

Embodiment 3

[0044] The same saturated brine of Example 1 is sent into the reaction tank, and sodium hydroxide 0.4g / L, sodium carbonate 1.6g / L and barium chloride 12.5g / L are added to react, after the reaction is completed, enter the preconditioner, add poly Sodium acrylate 60mg / l and sodium hypochlorite 40mg / l, after adsorption and co-precipitation, are pumped into the inorganic membrane cross-flow filter, using a ceramic membrane with a pore size of 0.02μm, 7 channels, the inner diameter of the channel is 6mm, and the cross-flow velocity is 2m / s, operating pressure 0.3MPa, membrane permeation flux 0.6m 3 m -2 h -1 , The experiment was carried out for 10h without backflushing the membrane. The filtered brine was measured by ICP (plasma emission spectrometry), and calcium, magnesium, and SS were not detected, and the sulfate content was 5.0mg / L, which fully met the standard of high-quality refined brine.

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Abstract

A membrane filter process for refining saline includes such steps as dissolving salt to obtain saturated solution, adding sodium hydroxide, sodium carbonate and barium chloride, reaction to generate magnesium hydroxide, calcium carbonate and barium sulfate, adding coagulating precipitant and oxidant for pre-treating, adsorbing and depositing to remove magnesium hydroxide colloid and part of particles, cross-flow filtering by inorganic membrane, and ion exchange.

Description

technical field [0001] The invention relates to a method for refining salt water in chlor-alkali industry, in particular to a method for refining salt water using inorganic membrane cross-flow filtration technology. Background technique [0002] Electrolysis methods in the chlor-alkali process mainly include diaphragm method, mercury method, and ion exchange membrane method. Among them, the mercury method has been gradually eliminated because mercury is recognized as a toxic substance. Now the diaphragm method and the ion exchange membrane method are more widely used. Favored and adopted by more and more chlor-alkali plants. Ion membrane is the core part of ion membrane caustic soda production. Although it does not directly participate in electrochemical reactions, it affects physical processes such as mass transfer and electrical conduction. The Ca in its operating medium brine 2+ , Mg 2+ Impurities such as OH permeate from the cathode chamber during the electrolysis pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01D3/06C01D3/14B01D61/00C02F1/44
Inventor 徐南平邢卫红
Owner JIANGSU JIUWU HITECH
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