CN-115196672-B - Method for recycling arsenic from high-concentration arsenic-containing wastewater

Abstract

The invention provides a method for recycling arsenic from high-concentration arsenic-containing wastewater, which comprises the following steps of a) mixing the high-concentration arsenic-containing wastewater with concentrated sulfuric acid for the first time, distilling for the first time to obtain a first acid liquor and a first arsenic-rich liquor respectively, b) mixing the first arsenic-rich liquor obtained in the step a) with the concentrated sulfuric acid for the second time, and distilling for the second time to obtain a second acid liquor and arsenic trichloride respectively. Compared with the prior art, the method has the advantages that the process is simple and easy to operate, the used sulfuric acid can be recycled after dehydration treatment, waste residues are not generated in the process, post treatment is not needed, and meanwhile, the obtained arsenic trichloride has higher purity and can be used as a raw material for producing high-purity arsenic.

Inventors

• JIA XINGWEI
• LI RUXU
• YIN LIANG
• ZHU LIU

Assignees

• 广东先导稀材股份有限公司

Dates

Publication Date

20260505

Application Date

20210414

Claims (5)

1. 1. A method for recovering arsenic from high-concentration arsenic-containing wastewater, comprising the steps of: a) Mixing high-concentration arsenic-containing wastewater with concentrated sulfuric acid for the first time, and then carrying out first distillation to obtain first acid liquor and first arsenic-rich liquor respectively in sequence, wherein the volume ratio of the high-concentration arsenic-containing wastewater to the concentrated sulfuric acid is 1 (1.5-3), the first distillation process comprises the steps of heating the mixture in a distillation device, collecting 115-120 ℃ fractions to obtain first acid liquor, and collecting 130-140 ℃ fractions to obtain first arsenic-rich liquor, wherein the first acid liquor is hydrochloric acid; b) The method comprises the steps of mixing the first arsenic-rich liquid obtained in the step a) with concentrated sulfuric acid for the second time, and then carrying out second distillation to obtain second acid liquid and arsenic trichloride respectively in sequence, wherein the volume ratio of the first arsenic-rich liquid to the concentrated sulfuric acid is 1 (0.5-1.5), the second distillation process comprises the steps of heating the mixture in a distillation device, collecting fractions at 115-120 ℃ to obtain second acid liquid, and collecting fractions at 130-140 ℃ to obtain second arsenic-rich liquid, namely arsenic trichloride, and the second acid liquid is hydrochloric acid.
2. 2. The method for recovering arsenic from high-concentration arsenic-containing wastewater according to claim 1, wherein the arsenic content in the high-concentration arsenic-containing wastewater in step a) is 20g/L to 80g/L and the HCl content is 4mol/L to 11mol/L.
3. 3. The method for recovering arsenic from high-concentration arsenic-containing wastewater according to claim 1, wherein the concentrated sulfuric acid in the step a) is sulfuric acid having a mass fraction of more than 90%.
4. 4. The method for recovering arsenic from high-concentration arsenic-containing wastewater according to claim 1, wherein the first mixing in step a) is specifically: adding concentrated sulfuric acid into the high-concentration arsenic-containing wastewater, and stirring for 1-4 hours to complete the first mixing process.
5. 5. The method for recovering arsenic from high-concentration arsenic-containing wastewater according to claim 1, wherein the second mixing in step b) is specifically: Adding concentrated sulfuric acid into the first arsenic-rich liquid, and mixing to complete the second mixing process.

Description

Method for recycling arsenic from high-concentration arsenic-containing wastewater Technical Field The invention relates to the technical field of wastewater treatment, in particular to a method for recycling arsenic from high-concentration arsenic-containing wastewater. Background As an important chemical raw material, high-purity arsenic is widely applied to the fields of manufacturing compound semiconductors, infrared transmission glass, hard alloy, medicines and the like. In the production process of high-purity arsenic, a large amount of arsenic-containing wastewater is generated, and arsenic-containing substances bring serious harm to organisms and the environment, so that the arsenic-containing wastewater can be discharged after reaching the standard through innocent treatment. The current methods for treating arsenic-containing wastewater mainly comprise a chemical precipitation method, an adsorption method, a microbiological method and the like, wherein the most widely applied method is the chemical precipitation method. The chemical precipitation method adopts acid-base neutralization, flocculant precipitation, sulfide precipitation and the like to separate arsenic from water, and the method is simple to operate, but has the problems that the slag amount generated in the implementation process is large, the arsenic-containing waste residue still needs to be subjected to secondary treatment, secondary pollution is easy to generate and the like. The adsorption method is to adopt an adsorbent prepared by chemical synthesis or natural materials after treatment, and is used for adsorbing arsenic in wastewater, the adsorption effect is good, but how the adsorbed arsenic-containing materials are treated still needs further research and exploration. The microbial method adopts bacteria to treat arsenic-containing wastewater, so that arsenic is precipitated in the form of scorodite to achieve the arsenic removal effect, but the bacterial culture period is longer, the requirements on the water environment are higher, and the industrial implementation is more difficult. Disclosure of Invention In view of the above, the present invention aims to provide a method for recovering arsenic from high-concentration arsenic-containing wastewater, which has the advantages of simple process, easy operation, recycling of sulfuric acid, no waste residue generation, no need of post-treatment, and high purity of the obtained arsenic trichloride, and can be used as a raw material for producing high-purity arsenic. The invention provides a method for recycling arsenic from high-concentration arsenic-containing wastewater, which comprises the following steps: a) Mixing high-concentration arsenic-containing wastewater with concentrated sulfuric acid for the first time, and then performing first distillation to obtain a first acid liquor and a first arsenic-rich liquor respectively; b) And c) mixing the first arsenic-rich liquid obtained in the step a) with concentrated sulfuric acid for the second time, and then performing second distillation to obtain second acid liquid and arsenic trichloride respectively. Preferably, in the high-concentration arsenic-containing wastewater in the step a), the arsenic content is 20g/L to 80g/L, and the HCl content is 4mol/L to 11mol/L. Preferably, the concentrated sulfuric acid in the step a) is sulfuric acid with a mass fraction of more than 90%. Preferably, in the step a), the volume ratio of the high-concentration arsenic-containing wastewater to the concentrated sulfuric acid is 1 (1.5-3). Preferably, the first mixing in step a) is specifically: adding concentrated sulfuric acid into the high-concentration arsenic-containing wastewater, and stirring for 1-4 hours to complete the first mixing process. Preferably, the first distillation in step a) is specifically performed by: Heating the mixture in a distillation device, collecting fractions at 115-120 ℃ to obtain a first acid solution, and collecting fractions at 130-140 ℃ to obtain a first arsenic-rich solution. Preferably, in the step b), the volume ratio of the first arsenic-rich liquid to the concentrated sulfuric acid is 1 (0.5-1.5). Preferably, the second mixing in step b) is specifically performed by: Adding concentrated sulfuric acid into the first arsenic-rich liquid, and mixing to complete the second mixing process. Preferably, the second distillation in step b) is performed by: Heating the mixture in a distillation device, collecting fractions at 115-120 ℃ to obtain second acid liquor, and collecting fractions at 130-140 ℃ to obtain second arsenic-rich liquor, namely arsenic trichloride. Preferably, the first acid solution and the second acid solution are hydrochloric acid. The invention provides a method for recycling arsenic from high-concentration arsenic-containing wastewater, which comprises the following steps of a) mixing the high-concentration arsenic-containing wastewater with concentrated sulfuric acid for the first t