Process for freezing and denitrating sodium chlorate mother liquor by aid of membrane methods

A technology for freezing denitration and sodium chlorate, applied in the field of electrolysis process of halogen or its compounds, can solve the problems of inability to apply sodium chlorate, inability to apply, high production cost and use cost, etc. Need, the effect of high added value of the product

Inactive Publication Date: 2018-09-14
HUNAN HENGGUANG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this process is currently only applicable to light brine or refined brine in the ionic membrane caustic soda industry, and cannot be directly applied in the electrolysis industry to manufacture sodium chlorate
[0006] Because a large amount of strong oxidizing sodium chlorate containe

Method used

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  • Process for freezing and denitrating sodium chlorate mother liquor by aid of membrane methods

Examples

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Embodiment 1

[0033] One of the embodiment of a kind of sodium chlorate mother solution membrane freezing denitrification process of the present invention, such as figure 1 , including the following steps:

[0034] (1) Dilution: Dilute the sodium chlorate mother liquor with water in the mixing tank so that the sodium chlorate concentration is lower than 200 g / L to obtain a sodium chlorate dilution; the sodium chlorate mother liquor comes out of the sodium chlorate electrolytic cell After the electrolyte solution is evaporated and crystallized, the mother liquor after centrifuge separation is a saturated solution of sodium chlorate at 40°C;

[0035] (2) Pretreatment: coarse filtration of sodium chlorate dilution, pH adjustment, dechlorination (adding Na 2 SO 3 Removal of free chlorine), pretreatment of fine filtration to obtain sodium chlorate pretreatment solution;

[0036] (3) Concentration: The sodium chlorate pretreatment liquid enters the nanofiltration membrane concentration system...

Embodiment 2

[0045] One of the embodiment of a kind of sodium chlorate mother liquid membrane freezing denitrification process of the present invention, the main technical scheme of this embodiment 2 is basically the same as that of embodiment 1, and the features not explained in this embodiment 2 are adopted in embodiment The explanation in 1 will not be repeated here. The difference between this example and Example 1 lies in: Step (1) Dilute the sodium chlorate mother liquor with water to make the sodium chlorate concentration 150 g / L. The volume ratio of sodium chlorate mother liquor to added water is 1:3.

[0046] Specifically, sodium chlorate mother liquor (consisting of sodium chloride concentration 120g / L, sodium sulfate concentration 15 g / L, sodium chlorate concentration 600g / L), 1 m 3 / h (45°C), add process water 3m into the mixing tank 3 / h, and centrifuge crystallization mother liquor (composed of sodium chloride concentration 30g / L, sodium sulfate concentration 17.5 g / L, sodi...

Embodiment 3

[0048] One of the embodiment of a kind of sodium chlorate mother liquor membrane freezing denitrification process of the present invention, the main technical scheme of the present embodiment 3 is basically the same as that of the embodiment 2, and the features not explained in the present embodiment 3 are adopted in the embodiment The explanation in 2 will not be repeated here. The difference between this example and Example 2 lies in: Step (1) Dilute the sodium chlorate mother liquor with water, so that the concentration of sodium chlorate is 117.6g / L. The volume ratio of sodium chlorate mother liquor to added water is 1:4.

[0049] Specifically, sodium chlorate mother liquor (consisting of sodium chloride concentration 120g / L, sodium sulfate concentration 15 g / L, sodium chlorate concentration 600g / L), 1 m 3 / h (45°C), add process water 4m into the mixing tank 3 / h, and the centrifuge crystallization mother liquor (composed of sodium chloride concentration 24g / L, sodium su...

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Abstract

The invention discloses a process for freezing and denitrating sodium chlorate mother liquor by the aid of membrane methods. The process includes steps of (1), diluting the sodium chlorate mother liquor, to be more specific, adding the sodium chlorate mother liquor into water and diluting the sodium chlorate mother liquor to allow the concentration of sodium chlorate in the sodium chlorate motherliquor to be lower than 200 g/L so as to obtain sodium chlorate diluent; (2), carrying out pretreatment including rough filtration, pH (potential of hydrogen) value regulation, dechlorination and finefiltration on the sodium chlorate diluent to obtain sodium chlorate pretreated liquor; (3), carrying out concentration, to be more specific, feeding the sodium chlorate pretreated liquor into a nano-filtration membrane concentration system by the aid of booster pumps and acquiring permeated liquor and concentrated liquor; (4), carrying out freezing and denitrating, to be more specific, feeding the concentrated liquor into a freezing system, crystallizing the concentrated liquid, and carrying out solid and liquid separation by the aid of a centrifugal machine to obtain mirabilite and crystallization mother liquor; (5), carrying out recycling by means of mixing the crystallization mother liquor and the sodium chlorate mother liquor with each other. The process for freezing and denitrating the sodium chlorate mother liquor by the aid of the membrane methods has the advantages that the process is simple, is low in cost and has a high additional value, new chemical impurities can be prevented from being introduced into the sodium chlorate mother liquor, and impurities in the sodium chlorate mother liquor can be effectively removed by the aid of the process.

Description

technical field [0001] The invention relates to the technical field of the electrolysis process of halogens or their compounds, in particular to a sodium chlorate mother liquor membrane freezing and denitrification process. Background technique [0002] Sodium chlorate is usually obtained through the electrolysis of industrial salt. The main impurities in raw salt, such as calcium, magnesium, and sulfate ions, are enriched during the production process, which will seriously affect the electrolysis operation. Calcium and magnesium ions will generate hydroxide on the cathode side and cause deposition on the electrode, which will increase the resistance and increase the cell voltage. The mother liquor of sodium chlorate contains unelectrolyzed sodium chloride, and the presence of sodium sulfate will reduce the concentration of sodium chloride in the electrolyte in the sodium chlorate electrolytic cell, which is unfavorable for the balance of the electrolytic reaction. In the m...

Claims

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Application Information

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IPC IPC(8): C01B11/14C01D5/16
CPCC01B11/145C01D5/16C01P2006/80
Inventor 伍小望易重庆贺学军罗喜元曹立祥胡建新
Owner HUNAN HENGGUANG TECH
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