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Method for refining ionic membrane caustic soda primary refined brine

A technology of ionic membrane caustic soda and refined brine, applied in the direction of alkali metal chloride, alkali metal halide purification, electrolytic components, etc., can solve the problems of high cost, membrane tube blockage, restriction, etc., and achieve low energy consumption and membrane flux The effect of large and small transmembrane pressure difference

Active Publication Date: 2021-02-26
南京纳亿工程技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004]Due to the presence of calcium and magnesium impurities and water-insoluble substances in the raw salt, membrane filtration brine refining without pretreatment has been unable to implement chlor-alkali in China. The floating clarification launched at the end of the last century Barrel pretreatment + PTFE membrane filtration process has played a very good role in improving the quality of China's chlor-alkali primary brine. Most chlor-alkali users choose floating clarifier tank pretreatment + PTFE membrane filtration process for primary brine refining, but with time With the passage of time, the technical progress of the primary brine PTFE membrane filtration and purification has been restricted due to the high cost of the floating clarification preprocessor and the difficulty of anti-corrosion.
[0005]There was a company that used tubular ceramic membranes to filter the primary brine of chlor-alkali ion membrane caustic soda. The initial application of pretreatment has gradually developed into a brine refining process that replaces the plate and frame filter press with coarse filtration, and then passes through ceramic membrane filtration. However, due to the small inner diameter of the tubular ceramic membrane, too high SS enters the membrane tube to cause membrane If the tube is clogged, the solid content of the brine entering the membrane must be reduced, so it is particularly necessary to use a plate and frame filter press or other methods of coarse filtration
[0006]Cancellation of pretreatment, membrane filtration and refining of saturated brine after chemical reaction has become the goal of primary brine refining in chlor-alkali enterprises, but so far, no enterprise has can achieve this

Method used

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  • Method for refining ionic membrane caustic soda primary refined brine
  • Method for refining ionic membrane caustic soda primary refined brine
  • Method for refining ionic membrane caustic soda primary refined brine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Improvement Pilot Test of Primary Refined Brine in a Chlor-Alkali Enterprise

[0048] The existing ionic membrane caustic soda primary brine refining system adopts pre-reaction adding sodium hydroxide to remove magnesium, floating clarifier tank as pretreatment of coarse brine, post-reaction adding sodium carbonate to remove calcium, and PTFE organic membrane filtration to remove the water-insoluble matter formed by the reaction. Process, calcium and magnesium dosing to control the over-alkaline amount of sodium hydroxide and sodium carbonate, so that the refined brine is alkaline, pH is about 10.5-11.5, sodium hydroxide is about 0.1-0.3g / L; sodium carbonate is about 0.3-0.5g / L, the pretreatment of this existing process is the need for the purification of PTFE organic membrane filtration. Without floating clarification pretreatment, the flow rate of PTFE organic membrane filtration fluctuates greatly, and the output of refined brine cannot be stably guaranteed to meet t...

Embodiment 2

[0066] A chemical plant adopts nanofiltration membrane salt separation, reverse osmosis membrane concentration, and evaporation salt extraction processes in the zero-discharge treatment of high-salt inorganic wastewater. The sodium chloride in the wastewater is 10g / L, and the Ca 2+ About 500mg / L, Mg 2+ About 100mg / L, sulfate about 5000mg / L. In order to avoid the impact of calcium sulfate scaling on nanofiltration membranes, reverse osmosis membranes and evaporation equipment caused by the concentration and enrichment of calcium magnesium ions and sulfate radicals, it was decided to use dosing reaction and membrane separation of magnesium hydroxide and calcium carbonate as nanofiltration Membrane pretreatment experiments.

[0067] The experiment adopts the reaction of adding sodium hydroxide and sodium carbonate under normal temperature conditions to react calcium and magnesium ions into magnesium hydroxide and calcium carbonate solids, and separate solid and liquid through fl...

Embodiment 3

[0083] Sodium chlorate production of brine refining currently adopts the refining process of Doyle clarifier + sand filter + carbon tube filtration, which has the characteristics of long process, large investment, high labor intensity, difficult management, and poor quality of brine. The refined brine In general Ca 2+ +Mg 2+ All around 10mg / L, SS>5mg / L.

[0084] The existing sodium chlorate brine is filtered and refined, with a processing capacity of 45m 3 / h, sodium chloride in raw brine is 100g / L, sodium chlorate is 530g / L, Ca 2+ +Mg 2+ It is 100mg / L, containing a small amount of iron filings, etc. Using sodium hydroxide to remove magnesium, sodium carbonate to remove calcium, and flat ceramic membrane filtration refining process, the production requires Ca in the purified liquid 2+ +Mg 2+ Not more than 1mg / L, and the water-insoluble (SS) content is not more than 1mg / L. The specific method is as follows:

[0085] (1) The concentration of each component of sodium chlo...

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Abstract

The invention relates to a method for refining ionic membrane caustic soda primary refined brine, which comprises the following steps: adding sodium carbonate into saturated brine to react with calcium ions to form calcium carbonate, and adding sodium hydroxide to react with magnesium ions to form magnesium hydroxide; so that primary refined brine meeting the refining requirement of the ionic membrane caustic soda secondary brine is obtained by directly adopting a plate ceramic membrane for filtration, calcium and magnesium ions are smaller than or equal to 1 mg / L, and suspended solids are smaller than or equal to 1 mg / L. Compared with the prior art, the method has the advantages that the conventional pretreatment process is omitted, and the high-quality and stable refined brine is obtained at a time.

Description

technical field [0001] The invention relates to a method for refining brine, in particular to a method for refining brine with ionic membrane caustic soda once refined. Background technique [0002] The use of saturated sodium chloride aqueous solution to produce caustic soda is a mature technology. Since the successful application of ion-exchange membrane soda production technology in China's chlor-alkali industry in the mid-1980s, China's chlor-alkali industry has made rapid progress in terms of technology and equipment, and its production capacity has increased. It ranks first in the world. With the continuous advancement of technology, obtaining high-quality brine, reducing the cost of sodium chloride raw materials, reducing the cost of brine refining, reducing electrolysis power consumption, and prolonging the life of ion membranes have become the goals of various manufacturers in the chlor-alkali industry. [0003] Ionic membrane caustic soda has strict requirements o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01D3/14C01D3/04C25B1/34
CPCC01D3/14C01D3/04C25B1/34Y02P20/133
Inventor 程雄程淏奇
Owner 南京纳亿工程技术有限公司
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