Method for preparing sodium fluoride from defluorination residue generated in production of phosphoric acid by wet process

A wet-process phosphoric acid, sodium fluoride technology, applied in the direction of alkali metal fluoride, etc., can solve the problem of difficult separation of sodium fluoride crystals and silica, achieve low silicon content, reduce production costs, reduce water consumption and mother liquor The effect of emissions

Active Publication Date: 2015-03-04
GUIZHOU CHANHEN CHEM CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a method for producing coarse sodium fluoride crystals, which can also solve th

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  • Method for preparing sodium fluoride from defluorination residue generated in production of phosphoric acid by wet process

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Effect test

Embodiment 1

[0034] 1) Prepare wet-process phosphoric acid defluorination slag with mother liquor to make a slurry with a specific gravity of 1.18g / ml; use mother liquor for sodium carbonate to prepare a solution with a specific gravity of 1.25g / ml; wet-process phosphoric acid defluorination slag contains P 2 o 5 : 0.52%, fluorine: 38.12%, SO 4 2- : 3.51%, moisture: 22.12%.

[0035] 2) The defluorinated slag slurry and sodium carbonate solution prepared in step 1) were respectively mixed with 0.70m 3 / h, 0.48m 3 The flow rate of / h is continuously added to the reaction crystallization tank, and the slurry containing fine sodium fluoride crystals obtained by centrifugation in step 4) is fed at a temperature of 1.85 m 3 / h into the reaction crystallization tank, the reaction decomposes and forms a slurry containing coarse particles of sodium fluoride crystals. The temperature in the tank is controlled at 90±5°C, the residence time of the material reaction is 4.5 hours, and the stirring ...

Embodiment 2

[0040] 1) The wet-process phosphoric acid defluorination slag is prepared into a slurry with a specific gravity of 1.23g / ml with the mother liquor; sodium carbonate is prepared with a mother liquor with a specific gravity of 1.27g / ml; the wet-process phosphoric acid defluorination slag contains P 2 o 5 : 0.46%, fluorine: 38.55%, SO 4 2- : 3.11%, moisture: 24.62%.

[0041] 2) The defluorinated slag slurry and sodium carbonate solution prepared in step 1) were respectively mixed with 0.75m 3 / h, 0.51m 3 The flow rate of / h is continuously added to the reaction crystallization tank, and the slurry containing fine sodium fluoride crystals obtained by step 4) is centrifuged at 1.75m 3 / h into the reaction crystallization tank, the reaction decomposes and forms a slurry containing coarse particles of sodium fluoride crystals. The temperature in the tank is controlled at 90±5°C, the residence time of the material reaction is 5.0 hours, and the stirring linear velocity in the tan...

Embodiment 3

[0046] 1) The wet-process phosphoric acid defluorination slag is prepared into a slurry with a specific gravity of 1.25g / ml with the mother liquor; sodium carbonate is prepared with a mother liquor with a specific gravity of a solution with a specific gravity of 1.30g / ml; the wet-process phosphoric acid defluorination slag contains P2O5: 0.55%, Fluorine: 38.42%, SO 4 2- : 3.28%, moisture: 23.75%.

[0047] 2) The defluorinated slag slurry and sodium carbonate solution prepared in step 1) were respectively mixed with 0.85m 3 / h, 0.53m 3 The flow rate of / h is continuously added to the reaction crystallization tank, and simultaneously the slurry containing fine sodium fluoride crystals obtained by screening and centrifugation in step 4) is 1.80m 3 / h into the reaction crystallization tank, the reaction decomposes and forms a slurry containing coarse particles of sodium fluoride crystals. The temperature in the tank is controlled at 90±5°C, the residence time of the material r...

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Abstract

The invention discloses a method for preparing sodium fluoride from defluorination residue generated in production of phosphoric acid by a wet process. The method comprises the following steps of respectively recycling mother liquid, sodium carbonate and defluorination residue slurry, reacting and crystallizing the defluorination residue slurry and a sodium carbonate solution and simultaneously returning fine sodium fluoride particles to the system for secondary growth. By larger sinking speed difference between sodium fluoride and silicon dioxide, the separation of sodium fluoride from silicon dioxide is achieved, and the technical problem of difficulty in separation of sodium fluoride from SiO2 is effectively solved. The sodium fluoride product obtained by the method is coarse, more than 85% of the sodium fluoride product has particle diameter greater than 0.35mm and the yield of fluorine in the sodium fluoride product is above 85%. By the method, the circulation of the mother liquid is achieved, the water consumption as well as the production cost are decreased, and the method has good social and economic values and is suitable for being popularized and applied.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing sodium fluoride from wet phosphoric acid defluorination slag. Background technique [0002] Defluorination slag is the waste residue produced in the defluorination process of wet-process phosphoric acid. The main component is sodium fluorosilicate, and it also contains a small amount of impurities such as phosphoric acid, sulfuric acid, and organic matter. Direct discharge not only pollutes the environment, occupies land resources, but also causes serious damage to fluorine resources. Waste, therefore, the defluorination slag needs to be utilized as a resource to avoid environmental pollution. [0003] Utilizing the fluorine element in the wet-process phosphoric acid production system to produce sodium fluoride products has been reported, such as Chinese patent CN101717097A provides a method for separating sodium fluoride crystals and...

Claims

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Application Information

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IPC IPC(8): C01D3/02
Inventor 龙辉曾春华李剑秋马永强
Owner GUIZHOU CHANHEN CHEM CO LTD
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