Method for efficiently separating and recycling sodium hydroxide from alkaline sodium silicate

A sodium hydroxide, recycling technology, applied in the direction of alkali metal oxides/hydroxides, alkali metal silicates, chemical instruments and methods, etc., can solve the problem of difficult effective separation of solutions and small modulus of sodium metasilicate , low recycling efficiency and other issues, to achieve the effect of small loss, lower production cost, and lower cost

Active Publication Date: 2015-07-29
NANJING UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0008] The present invention aims at the problems existing in the existing fly ash production process of sodium metasilicate: solution is difficult to effectively separate, sodium metasilicate modulus is small, purity is low, cost is high, extraction efficiency is low, extraction effect is poor, recycling efficiency is low, etc. difficulty

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  • Method for efficiently separating and recycling sodium hydroxide from alkaline sodium silicate

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Embodiment 1

[0033] The present invention aims at existing fly ash production sodium metasilicate process existing: 1) sodium silicate and sodium hydroxide are difficult to effectively separate in alkaline sodium silicate solution, cause the sodium metasilicate modulus of production to be little, and purity 2) a single extractant has low extraction efficiency for high-concentration NaOH in alkaline sodium silicate, poor extraction effect, and low recycling efficiency.

[0034] combined with figure 1 , a method for efficient separation and recycling of sodium hydroxide in alkaline sodium silicate in this embodiment is suitable for the production of high modulus sodium metasilicate extracted from pulverized coal. The steps are:

[0035] (A) A high-concentration alkaline sodium silicate solution was obtained after the fly ash was leached with a NaOH solution having a mass concentration of 25%. The mass concentration of NaOH in the alkaline sodium silicate solution is 20%. Add the compound ...

Embodiment 2

[0041] A method for efficient separation and recycling of sodium hydroxide in alkaline sodium silicate in this embodiment is basically the same as in embodiment 1, except that some parameters have been adjusted, and the same effect can still be achieved. details as follows:

[0042] In step (A), the fly ash is leached with a NaOH solution having a mass concentration of 30%, to obtain an alkaline sodium silicate solution. Wherein the mass concentration of the NaOH solution in the alkaline sodium silicate solution is 25%, and the extractant and the additive are compounded according to the volume ratio of 10:1 for extraction, wherein the extractant is n-hexanol and n-octanol The mixture, the mixing volume ratio is 2:1, the additive is C 18 Alkylphenol, the compound extractant is 3 times the volume of the filtrate, and the extraction temperature is 100°C.

[0043] The aqueous phase obtained in step (B) is stripped under 8bar pressure at 85°C, and after adding sodium metasilicate...

Embodiment 3

[0047] A method for efficient separation and recycling of sodium hydroxide in alkaline sodium silicate in this embodiment is basically the same as in embodiment 1, except that some parameters have been adjusted, and the same effect can still be achieved. details as follows:

[0048] In the step (A), the fly ash is leached with a NaOH solution having a mass concentration of 20%, to obtain an alkaline sodium silicate solution. Wherein the mass concentration of the NaOH solution in the alkaline sodium silicate solution is 15%, and the extractant and the additive are used for extraction according to a compound extractant compounded at a volume ratio of 10:1, wherein the extractant is composed of glycerin and C 10 Fatty alcohol composition, the volume ratio of the two is 1:1, and the additive is C 6 Alkylphenols and C 12 Alkylphenol mixture, the volume ratio of the two is 1:2, the volume of the compound extractant is 1.5 times the volume of the filtrate, and the extraction temper...

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Abstract

The invention discloses a method for efficiently separating and recycling sodium hydroxide from alkaline sodium silicate and belongs to the field of alkaline sodium silicate recycling comprehensive utilization. An efficient compound extractant is utilized to extract sodium hydroxide from alkaline sodium silicate, and a high-purity and high-modulus sodium metasilicate product is recovered by virtue of low-temperature crystallization, so that efficient separation of sodium silicate and sodium hydroxide and recycling of sodium hydroxide are realized; the compound extractant is prepared by compounding an extractant and an additive at a certain ratio, wherein the extractant is one of or a mixture of more selected from short-chain alcohols and long-chain fatty alcohols; the additive is one of or a mixture of more selected from long-chain alkylphenol substances; after pure water is adopted for re-extraction, sodium hydroxide in extraction raffinate can be directly returned to a pulverized fuel ash alkaline leaching process so as to be used mechanically. Compared with the traditional sodium hydroxide extraction technology, the method has the advantages of high extraction efficiency, good extraction effect, high alkali liquor cyclic utilization rate and the like and is capable of recovering high-purity sodium metasilicate products.

Description

technical field [0001] The invention belongs to the field of comprehensive utilization of alkaline sodium silicate resources, and more specifically relates to a method for efficient separation and recycling of sodium hydroxide in alkaline sodium silicate. Background technique [0002] my country's energy structure is coal-rich, oil-poor, and gas-poor. Therefore, coal occupies a very important position in my country's energy supply. However, coal combustion produces a large amount of solid waste such as fly ash, which brings great pressure to the ecological environment. According to statistics, the annual discharge of fly ash from thermal power plants in my country is as high as 400 million tons, and it is increasing year by year. Therefore, the development and utilization of fly ash has very important economic and social significance. [0003] Fly ash contains a lot of SiO 2 and Al 2 o 3 and other substances, among which SiO 2 The mass fraction is as high as 40-55%. Ho...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/32C01D1/34
Inventor 张炜铭吕路陈良汪林王林平徐敬生潘丙才
Owner NANJING UNIV
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