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Method for precipitating and stabilizing As from As-containing solution

A solution and arsenic precipitation technology, used in chemical instruments and methods, water pollutants, water/sludge/sewage treatment, etc. simple craftsmanship

Active Publication Date: 2012-09-19
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there have been many reports on the formation of scorodite, but the experimental conditions for its formation are demanding

Method used

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  • Method for precipitating and stabilizing As from As-containing solution
  • Method for precipitating and stabilizing As from As-containing solution
  • Method for precipitating and stabilizing As from As-containing solution

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1 The arsenic solution (pH=4) with a concentration of 10 g / L precipitates arsenic to form iron arsenate crystals.

[0029] Add 16.11g of crude sodium arsenate crystals into 250ml of distilled water, stir to dissolve, add 95% concentrated sulfuric acid drop by drop and measure the pH, adjust the pH to 4, add the prepared arsenic-containing solution into a 1000ml three-necked flask, heat in a water bath and Stir mechanically, set the temperature to 95° C., and the stirring speed to 200 rpm. Another 27.80g FeSO 4 ·7H 2 O was added to 250ml of distilled water, stirred to dissolve, and added to the preheated arsenic-containing solution. Under this condition, the molar mass ratio of iron to arsenic is 1.5, and the initial arsenic concentration is 10g / L. Continue heating in a water bath to 95°C with stirring, blow in preheated air and time the reaction for 5 hours, and control the air flow rate to 120 L / h. After the reaction, the solution was cooled and allowed to ...

Embodiment 2

[0031] Embodiment 2 concentration is that 50g / L arsenic-containing solution synthesizes iron arsenate crystal

[0032] Add 80.54g of crude sodium arsenate crystals to 250ml of distilled water, stir to dissolve, add 95% concentrated sulfuric acid drop by drop and measure the pH, adjust the pH to 4, add the prepared arsenic-containing solution into a 1000ml three-necked flask, heat in a water bath and Mechanical stirring, the stirring speed is 200rpm. Take 139.01g FeSO 4 ·7H 2 O was added to 250ml of distilled water, stirred to dissolve, and slowly added to the preheated arsenic-containing solution. Under this condition, the molar mass ratio of iron to arsenic is 1.5, and the initial arsenic concentration is 50g / L. Continue heating to 95°C in a water bath with stirring, blow in preheated air and time the reaction for 7 hours, and control the air flow rate to 120 L / h. After the reaction, the reaction solution was cooled and allowed to stand, and the temperature was slightly l...

Embodiment 3

[0033] Example 3 Synthesis of ferric arsenate crystals under different reaction temperature conditions

[0034] Add 16.11g of crude sodium arsenate crystals into 250ml of distilled water, stir to dissolve, add 95% concentrated sulfuric acid drop by drop and measure the pH, adjust the pH to 4, add the prepared arsenic-containing solution into a 1000ml three-necked flask, heat in a water bath and Mechanical stirring, the stirring speed is 200rpm. Take 27.80g FeSO 4 ·7H 2O was added to 250ml of distilled water, stirred to dissolve, and added to the preheated arsenic-containing solution. Continue to heat in a water bath to 70, 80, and 95°C with stirring, blow in preheated air and time the reaction for 7 hours, and control the air flow rate to 120L / h. After the reaction, the reaction solution was cooled and left to stand, and the temperature was slightly lowered to 60°C. The solution was filtered while it was hot, and the sediment was washed once with 100ml of distilled water, a...

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Abstract

The invention discloses a method for precipitating and stabilizing As from As-containing solution. According to the method, ferrous salt is used as As precipitator; through the air oxidation in the As-containing solution in a weak acid condition, Fe<2+> is oxidized into Fe<3+>; and Fe<3+> reacts with As to generate precipitate with high stability and low As leaching toxicity. The method is simple in technology, and generates the precipitate which is ferric arsenate crystalline compound-scorodite crystal FeAsO4. 2H2O under the conditions that the pH value is 4-6, the temperature is 70-95 DEG C, the molar ratio between Fe and As is 1-1.5, the air flow rate is 120-200L / h and the reaction time is 5-7h; the precipitate As has the leaching toxicity concentration of 1-2mg / L which is lower than the limit value of Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity (GB 5085.3-2007); and the harmless stabilizing treatment for the As-containing solution can be realized.

Description

technical field [0001] The invention belongs to the technical field of heavy metal wastewater treatment, and specifically relates to a method for precipitating and stabilizing arsenic from an arsenic-containing solution, which is suitable for the purification of arsenic-containing industrial wastewater and the treatment of arsenic-containing waste liquid. Background technique [0002] Arsenic is one of the main associated elements in non-ferrous metal ores, such as high-arsenic copper and gold concentrates, the content of arsenic can even be as high as 20-30%. Various arsenic-containing solutions are often produced in the smelting process of non-ferrous metals, and these arsenic-containing substances are highly toxic, bioaccumulative and carcinogenic, and must be converted into a form that is harmless to the environment before they can be discharged. [0003] At present, the comparatively systematic treatment methods of arsenic-containing wastewater include chemical precipit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/72C02F101/20
Inventor 柴立元杨志辉熊珊蔡练兵刘维陈永明
Owner CENT SOUTH UNIV
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