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Treating method of arsenic in waste acid

A treatment method, technology of arsenic polluted acid, applied in the direction of water/sewage multi-stage treatment, neutralized water/sewage treatment, oxidized water/sewage treatment, etc., can solve the final disposal or treatment of unfavorable waste residues, high treatment costs, and the amount of waste residues to reduce the risk of secondary pollution, reduce the output of waste residue, and reduce the amount of iron used

Active Publication Date: 2012-07-04
SHENYANG INST OF APPL ECOLOGY CHINESE ACAD OF SCI
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Problems solved by technology

[0004] As a treatment method for arsenic in sewage acid, the extraction and ion exchange methods have the problems of complicated process and high treatment cost; the sodium sulfide precipitation method is to convert arsenic into arsenic sulfide, and prepare arsenic trioxide through oxidation, reduction, crystallization and other processes. The sodium sulfide The arsenic recovery and utilization rate of the precipitation method is high, but the process is long and the treatment cost is high; the lime-iron salt method adds iron salt to the arsenic-containing sewage acid, so that the arsenic in the arsenic-containing sewage acid is precipitated in the form of arsenic-iron co-precipitation This method is low in cost and simple in process for treating arsenic-containing polluted acid. However, in this method, iron salts with a molar ratio of iron to arsenic of more than 4:1 are usually required, and there is a large amount of waste residue, which is not conducive to the final disposal or treatment of waste residue.

Method used

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  • Treating method of arsenic in waste acid
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  • Treating method of arsenic in waste acid

Examples

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Effect test

Embodiment 1

[0028] Sewage acid contains sulfuric acid 50g / L, As(III): 5g / L, calcium oxide is added at room temperature to neutralize to pH = 1, solid gypsum is obtained after solid-liquid separation, supernatant is added H 2 o 2 and ferric sulfate to make H 2 o 2 The molar ratio of Fe and As is 1.2, and the molar ratio of Fe and As is 0.8. After 30 minutes of oxidation reaction, continue to add calcium oxide to neutralize to pH=2. After solid-liquid separation, the supernatant should further remove arsenic, and add 1M H 2 SO 4 , dissolve part of the precipitate, make the pH of the mixture at 1.4, heat the mixture to 95°C, keep it under mechanical stirring (200rpm) for 5h, continue solid-liquid separation, and obtain a stable mixed precipitate of scorodite and calcium sulfate. The X-ray diffraction analysis and scanning electron microscope analysis pictures are as follows figure 1 and figure 2 As shown, the liquid after the two solid-liquid separations is added with iron sulfate at...

Embodiment 2

[0030] Sewage acid contains sulfuric acid 50g / L, As(III): 10g / L, add calcium oxide at room temperature to neutralize to pH=0.9, obtain solid gypsum after solid-liquid separation, add H to the supernatant 2 o 2 and ferric nitrate to make H 2 o 2 The molar ratio of Fe and As is 1.3, and the molar ratio of Fe and As is 1.0. After 30 minutes of oxidation reaction, continue to add calcium oxide to neutralize to pH=4. After solid-liquid separation, the supernatant should further remove arsenic, and add 2M H 2 SO 4 , dissolve part of the precipitate, make the pH of the mixture at 1.5, heat the mixture to 90°C, keep it under mechanical stirring (200rpm) for 6h, and continue the solid-liquid separation to obtain a stable mixed precipitate of scorodite and calcium sulfate. Add iron sulfate to the liquid after liquid separation according to the molar ratio of iron to arsenic being 2, continue to neutralize with calcium oxide suspension to pH=4, and separate solid and liquid.

Embodiment 3

[0032] Sewage acid contains sulfuric acid 80g / L, As(III): 8g / L, calcium oxide is added at room temperature to neutralize to pH = 1.2, solid gypsum is obtained after solid-liquid separation, supernatant is added H 2 o 2 and ferric chloride to make H 2 o 2 The molar ratio of Fe and As is 1.5, and the molar ratio of Fe and As is 1.2. After 30 minutes of oxidation reaction, continue to add calcium oxide to neutralize to pH=1.8. After solid-liquid separation, the supernatant should further remove arsenic, and add 1M H 2 SO 4 , dissolve part of the precipitate, so that the pH of the resulting mixture is 0.8, heat the solution to 80 ° C, keep it for 8 hours, and continue the solid-liquid separation to obtain a stable mixed precipitate of scorodite and calcium sulfate. The liquid after the two solid-liquid separations is press The molar ratio of iron to arsenic is 6, add ferric sulfate, continue to neutralize with calcium oxide suspension to pH=10, and separate solid and liquid. ...

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Abstract

The invention provides a treating method of arsenic in waste acid, which comprises the steps of enabling arsenic in waste acid to form amorphous ferric arsenate precipitation under the conditions of lower Fe / As molar ratio and a certain pH value, adding acid for re-dissolution, heating, carrying on enrichment and concentration on the arsenic in the waste acid, and finally forming stable scoroditecrystals to remove the arsenic in the waste acid, so that the iron usage amount is greatly reduced, the economic cost is reduced, the slag amount is reduced, simultaneously the cost for high temperature transforming heating is reduced, stable solid waste containing arsenic can be obtained, and the secondary pollution to the environment due to the solid waste containing the arsenic can be reduced.

Description

technical field [0001] The invention belongs to the technical field of hydrometallurgy and environmental protection, and specifically relates to a method for treating arsenic in polluted acid. Background technique [0002] Polluted acid is a kind of dilute sulfuric acid produced in the process of making acid from flue gas in non-ferrous smelting and sulfuric acid industries. It usually contains toxic and harmful substances such as mercury, arsenic, cadmium, copper, lead, and zinc, and the content is higher than that of ordinary industrial wastewater. It cannot be discharged directly. , the heavy metals must be effectively removed to make the wastewater discharge meet the standard. Therefore, it is of certain importance and urgency to control the highly concentrated metal pollution acid. [0003] At present, the treatment technologies of polluted acid mainly include: lime method, lime-iron salt method, sulfuration method, adsorption and ion exchange method. Sewage acid wast...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F1/52C02F1/72C02F1/66
Inventor 贾永锋王宽岭
Owner SHENYANG INST OF APPL ECOLOGY CHINESE ACAD OF SCI
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