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Method for recycling waste gas containing fluorine

A waste gas recovery and ammonium fluoride technology, which is applied in separation methods, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of reduced purity, excess water, and reduced yield, and achieve the effect of improving purity and yield

Inactive Publication Date: 2010-05-19
SHANDONG HONGRI ACRON CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the method of document 1, the material containing more than 70% of water needs to be evaporated and concentrated, and a large amount of steam needs to be consumed
The method of Document 2 has a long process flow, and the final product is silica and cryolite with high added value, but its disadvantage is also obvious, that is, the water cannot be balanced: the three raw materials entering the system contain more than 70% water, and the whole There are as many as 4 operations in which washing water needs to be added during the process, and there is also a lot of water that needs to be treated and discharged
The whole operation process of the method of document 3 is carried out in ammonium fluoride saturated solution, causes the slurry after the reaction to contain ammonium fluoride crystals and silica precipitation at the same time, although this invention separates the two by sieving, But it will inevitably cause the yield of one product to decrease and the purity of the other product to decrease

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] (1) Absorb silicon tetrafluoride gas after dust removal with an ammonium fluoride solution with an initial concentration of 45%, control the reaction temperature at 80°C, and stop absorption when the ammonium fluoride concentration in the solution is about 5%.

[0025] (2) carry out ammoniation reaction with 80% ammonium fluorosilicate solution in step (1) and ammonia gas, control reaction temperature is 90 ℃, stop logical ammonia when ammonium fluoride concentration is 55% in the solution, reaction after After the slurry is settled and filtered, the filter residue is washed and dried to obtain precipitated silica (white carbon black) products.

[0026] (3) Cool the filtrate of step (2) from 90°C to 30°C to precipitate ammonium fluoride crystals, which are washed and dried to obtain ammonium fluoride products; the filtrate and lotion return to step (1) for circulation use.

[0027] (4) The 20% ammonium fluorosilicate solution in step (1) is deeply absorbed, so that the...

Embodiment 2

[0031] (1) Use an ammonium fluoride solution with an initial concentration of 25% to absorb the dedusted silicon tetrafluoride gas, control the reaction temperature to 60°C, and stop the absorption when the ammonium fluoride concentration in the solution is about 5%.

[0032] (2) carry out ammoniation reaction with 80% ammonium fluorosilicate solution in step (1) and ammonia gas, control reaction temperature is 80 ℃, stop logical ammonia when ammonium fluoride concentration is 52% in the solution, reaction after After the slurry is settled and filtered, the filter residue is washed and dried to obtain precipitated silica (white carbon black) products.

[0033] (3) Cool the filtrate of step (2) from 80°C to 20°C, and precipitate ammonium fluoride crystals, which are washed and dried to obtain ammonium fluoride products; the filtrate and lotion return to step (1) for circulation use.

[0034](4) The 20% ammonium fluorosilicate solution in step (1) is deeply absorbed, so that th...

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Abstract

The invention relates to a method for recycling waste gas containing fluorine, belonging to the technical field of chemical industrial production. The method comprises the following steps: absorbing silicon tetrafluoride by an ammonium fluoride solution to produce ammonium fluosilicate, then ammoniating the ammonium fluosilicate to reduce the ammonium fluosilicate to ammonium fluoride, and simultaneously, generating precipitate silica (silica white); after separating the precipitate silica (silica white), by using the changing solubility of ammonium fluoride resulting from the change of temperature, separating the ammonium fluoride by cooling and crystallization; simultaneously, in order to ensure water balance of the overall system and diversification of products, enabling part of the ammonium fluosilicate and potassium chloride (or potassium sulfate) to carry out metathetical reaction to generate potassium fluosilicate precipitate and ammonium chloride (or ammonium sulfate); and after the precipitate silica is separated, concentrating and crystallizing a mother solution to obtain ammonium chloride (or ammonium sulfate) fertilizer. The invention is mainly applied to the fertilizer production industry.

Description

technical field [0001] The invention relates to a method for recycling fluorine-containing waste gas, which belongs to the technical field of inorganic chemical industry production, and specifically relates to a method for producing potassium fluorosilicate and white carbon black by using fluorine-containing waste gas. Background technique [0002] In the process of producing ordinary calcium superphosphate, wet-process phosphoric acid, heavy calcium and other phosphorus chemical processes from phosphorous rock, part of the fluorine and silicon in the phosphorous rock escapes in the form of silicon tetrafluoride, forming fluorine-containing waste gas. Most of the existing treatment is to absorb waste gas with water to generate silica gel and fluosilicic acid, and then react fluosilicic acid with sodium chloride (or sodium sulfate) to generate sodium fluosilicate and hydrochloric acid (or sulfuric acid). Because silica gel contains impurities such as phosphorus and fluorine, ...

Claims

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Application Information

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IPC IPC(8): B01D53/78C01C1/16C01B33/113C01C1/244B01D53/68
Inventor 李新柱胡兆平张西兴张朝森李善层
Owner SHANDONG HONGRI ACRON CHEM
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