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Environment-friendly separation and recovery method of fluorine in fluorine-containing waste liquid

A technology of separation and recovery, waste liquid, applied in the direction of fluorine/hydrogen fluoride, hydrogen fluoride, magnesium fluoride, etc., to achieve the effect of low production cost, no three waste discharge, good defluorination effect

Inactive Publication Date: 2016-09-21
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has simple equipment and easy operation, and does not require adsorption regeneration process, but it will also produce fluorine-containing solid waste

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Take 3m of acid etching fluorine-containing waste liquid from the glass factory 3 , filter to remove suspended solids, and press F - Form MgF 2 Precipitation is 5 times the stoichiometric number, stirring at room temperature and adding Mg(OH) 2 After dissolution, add NaOH to adjust the pH value to 10.2, stir at 85°C for 1 hour, and filter to obtain magnesium fluoride precipitate and defluoridated solution. After defluoridation, the liquid is sent to the wastewater reuse process for treatment, and the resulting magnesium fluoride precipitate contains MgF 2 96.7% are sold directly as products. The test results before and after the treatment of fluorine-containing waste liquid are as follows:

[0027]

Embodiment 2

[0029] Take 10L of fluorine-containing waste liquid produced by the fluorine chemical plant, press the F - Form MgF 2 Add MgCO 1.5 times the stoichiometric number of precipitation 3 As a precipitating agent, after stirring at 70°C for 1 hour, adjust the pH of the solution to 8.5 with sodium hydroxide, continue the reaction for 2.5 hours, and filter to obtain magnesium fluoride precipitate and defluoridated solution. After defluoridation, the liquid is sent to the waste water reuse process for treatment. The obtained magnesium fluoride precipitate is first washed with a sodium hydroxide solution with a pH value of 10.62 to remove aluminum, and then press MgF 2 Converted to MgSO 4 Add concentrated sulfuric acid with a concentration of 98% to 1.1 times the stoichiometric number, act at 210°C for 1.5 hours, absorb the evaporated HF gas with aluminum chloride solution, add ammonia after absorption, neutralize and filter to obtain aluminum fluoride, and evaporate the residue as so...

Embodiment 3

[0032]Take 3L of fluorine-containing waste liquid produced in the tantalum and niobium smelting process, press the F - Form MgF 2 Add MgSO to 1.05 times the stoichiometric number of precipitation 4 , stirred at room temperature for 1.5h, and filtered to obtain magnesium fluoride precipitate and defluoridated liquid. After defluoridation, the liquid is sent to the wastewater reuse process for treatment, and the magnesium fluoride precipitate obtained is classified as MgF 2 Converted to MgSO 4 2 times the stoichiometric number, stirring and adding H at a concentration of 65wt% 2 SO 4 Decompose in medium, react at 120°C for 2.5h, the evaporated HF gas is condensed to obtain hydrofluoric acid with a concentration of 45%, add concentrated sulfuric acid to adjust H after evaporation 2 SO 4 Concentration reaches 63wt%, cooling and crystallization at room temperature, filtration to obtain magnesium sulfate crystals and crystallization mother liquor. The obtained magnesium sulfa...

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Abstract

The invention discloses an environment-friendly separation and recovery method of fluorine in a fluorine-containing waste liquid. According to the invention, a magnesium-containing compound is added into the fluorine-containing waste liquid as a precipitation agent, such that fluorine in the waste liquid is selectively precipitated; filtering is carried out, and fluorine-removed liquid and magnesium fluoride precipitate are obtained; the fluorine-removed liquid is used in waste water recycling; the magnesium fluoride precipitate is decomposed with sulfuric acid, such that a series of compounds of fluorine are obtained; decomposition residue is subjected to a dissolution-crystallization treatment, such that magnesium sulfate crystals are obtained; the obtained magnesium sulfate crystals are returned and recycled in the fluorine selective precipitation process; the crystallization mother liquor of magnesium sulfate is returned to the dissolution-crystallization process or the magnesium fluoride precipitation decomposition process. The method has the advantages of simple process, simple operation, low production cost, and good fluorine-removing effect. With the method, fluorine resource utilization is realized. The method also has the advantages of no fluorine-containing waste production and no three-waste emission.

Description

technical field [0001] The invention discloses an environment-friendly separation and recovery method for fluorine in fluorine-containing waste liquid, which belongs to the technical fields of chemical industry and metallurgy. Background technique [0002] With the development of modern industry, the production, synthesis and application of fluorine and its compounds are increasing day by day, and more and more fluorine-containing waste liquids are produced. The treatment of fluorine-containing waste liquid is an important topic in the field of environmental protection. A lot of research has been done on the treatment of fluorine-containing waste liquid at home and abroad. The treatment methods of fluorine-containing waste liquid mainly include precipitation method, adsorption method, reverse osmosis method, biochemical method, liquid membrane method and electrocoagulation method. [0003] The precipitation method is to add chemicals to the fluorine-containing waste liquid ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F5/28C01F5/40C01B7/19
CPCC01F5/28C01B7/191C01F5/40
Inventor 王学文王明玉
Owner CENT SOUTH UNIV
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