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In-situ preparation of high-purity caf by multi-stage treatment of high-concentration fluorine-containing wastewater 2 Methods

An in-situ preparation, high-concentration technology, applied in the direction of calcium/strontium/barium halide, calcium/strontium/barium fluoride, etc., can solve the waste of fluorine resources, low calcium release efficiency of calcium carbonate, and low purity of calcium fluoride, etc. problem, to achieve the effect of improving the purity

Active Publication Date: 2017-11-03
SHANGHAI JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Considering the necessity of fluorine-containing wastewater treatment, and the conventional lime precipitation method not only causes waste of fluorine resources, but also brings great environmental risks, the current fluidized bed crystallization method of fluoride-containing wastewater directly prepares calcium fluoride. There are disadvantages such as the purity of the obtained calcium fluoride is not high, and the efficiency of calcium carbonate release is low.

Method used

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  • In-situ preparation of high-purity caf by multi-stage treatment of high-concentration fluorine-containing wastewater <sub>2</sub> Methods

Examples

Experimental program
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Effect test

Embodiment 1

[0038] The original fluorine-containing wastewater concentration is 3000mg / L, SO 4 2- The concentration is 500mg / L, and it also contains Cu 2+ The main metal ions are all below 30mg / L, and the TOC content is 40mg / L.

[0039] Step 1, BaCl 2 The dosage is 0.7 times the theoretical value, and the remaining SO 4 2- is 150mg / L.

[0040] Step 2, H 2 O 2 The dosage is 50 mmol / L, after the pH is adjusted to 4, 2+ The activated carbon adsorption tank 6, the amount of activated carbon used is 1g / L, and its BET is 300cm 2 / g, the Fe loading was 10 mg / g, the residence time was 20 min, the concentrations of various metal ions were all lower than 10 mg / L, and the TOC was reduced to 10 mg / L.

[0041] Step 3, the lime bed 7 is used as fluorine-containing wastewater to induce CaF 2 In the crystallization reactor, the original fluorine-containing wastewater is mixed with reflux water at the bottom of the reactor, and the influent [Ca 2+ ] / [F - ]=1.0mol / mol, using CaO with a content ...

Embodiment 2

[0044] The same procedure was carried out as described in Example 1. The concentration of fluorine-containing wastewater is 1000mg / L, the sulfate concentration is 300mg / L, the TOC content is 25mg / L, and the main component of metal ions is Cu 2+ , its concentration is lower than 15mg / L.

[0045] Step 1, adding barium chloride, the dosage is 0.8 times the theoretical value, and the residual sulfate concentration is 60 mg / L. Generated BaSO 4 The pellet was separated in a vertical centrifuge at 3000 rpm speed.

[0046] Step 2, H 2 O 2 The dosage is 150mmol / L, after the pH is adjusted to 4, 2+ The activated carbon adsorption tank 6, the amount of activated carbon used is 3g / L, and the BET is 500cm 2 / g, the Fe loading was 20mg / g, the residence time was 30min, the TOC content of the effluent after adsorption decreased to below 10mg / L, the Cu 2+ The ion concentrations were all lower than 10 mg / L.

[0047] Step 3, enter the lime bed 7 containing calcium oxide, [Ca 2+ ] / [F - ...

Embodiment 3

[0050] The same operation was performed as described in Example 1, but the treated water was different, and the control conditions and parameters were different. The concentration of fluorine-containing wastewater is 1800mg / L, the sulfate concentration is 430mg / L, the TOC content is 15mg / L, the Cu 2+ The concentration is 5mg / L.

[0051] Step 1, the barium salt adopts BaCl 2 , the dosage is 0.75 times the theoretical value, the residual SO 4 2- is 110mg / L.

[0052] Step 2, H 2 O 2 The dosage is 100 mmol / L, after the pH is adjusted to 4, 2+ Activated carbon adsorption tank 6, the amount of activated carbon is 2g / L, and its BET is 800cm 2 / g, the Fe loading is 30mg / g, the residence time is 40min, and the effluent Cu after adsorption 2+ The residual concentration was 1 mg / L, and the TOC content was reduced to 1 mg / L.

[0053] Step 3, enter the lime bed 7 containing calcium oxide, [Ca 2+ ] / [F - ]=1.2, the reflux ratio is 5, the rising flow rate is 50m / h, the initial fluo...

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Abstract

A method of preparing high-purity CaF2 in situ through high-concentration fluorine-containing waste water multi-stage treatment includes the processes of: optimizing concentration of SO4<2->, synchronously removing organic substances and heavy metal ions, slow-releasing calcium source on-situ, and performing a reaction with F<-> ion to quickly generate high-purity CaF2 precipitate. The high-concentration fluorine-containing waste water comes from an etching process. A pre-treatment process includes the steps of removing SO4<2->, removing the organic substances by H2O2 and adsorbing metal impurity ions by activated carbon. Through an impurity self-crystallization method, growth of CaF2 crystal is promoted. With the CaO as a calcium source, the fluorine-containing waste water passes through the surface of the CaO through thin layers, so that the Ca<2+> ions can be released by slow dissolution and are reacted with the F<-> to generate the CaF2 precipitate. The method employs a multi-stage process to recycle fluorine resource in the form of CaF2 from the high-concentration waste water generated in the etching process, so that the method not only reduces treatment cost of the fluorine-containing waste water in industry but also avoids resource loss of the fluorine. The method improves the purity of the CaF2, solves the difficult problem that small-granular CaF2 is difficult to precipitate and separate, achieves gradient utilization of the fluorine resource and completes total-recycling utilization of the waste water being higher than 50 mg / L in fluorine concentration.

Description

technical field [0001] The invention relates to a method for recovering fluorine resources, in particular to a method for preparing and separating high-purity calcium fluoride in high-concentration fluorine-containing wastewater, and belongs to the technical field of environmental protection. Background technique [0002] Industrial wastewater contains a large amount of fluoride. For example, in the wastewater discharged from the glass manufacturing industry, the fluoride content reaches 194-1980mg / L. The fluorine content in the factory's fluorine-containing wastewater reaches 1500mg / L. The wastewater discharged from the production of electronic components, electroplating operations, metal smelting and other industries contains high concentrations of fluoride. Among them, in the electronic component production industry, the output of fluorine-containing wastewater is large, mainly From the cleaning process, etching process. Take the fluorine-containing wastewater produced i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F11/22
CPCC01F11/22C01P2004/60C01P2006/12C01P2006/80
Inventor 楼紫阳尹常凯朱南文袁海平于豹徐怡婷
Owner SHANGHAI JIAOTONG UNIV