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A method for acid hydrolysis of calcium arsenate and/or calcium arsenite

A technology of calcium arsenite and calcium arsenate, applied in the field of waste treatment, can solve problems such as secondary pollution

Active Publication Date: 2018-12-14
SHENYANG INST OF APPL ECOLOGY CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Among them, the high-temperature alkali solution-arsenic extraction-sorodite precipitation technology and the lime method are efficient and economically feasible technologies for treating arsenic sulfide slag and arsenic-containing wastewater. Both methods will use lime to extract arsenic in the liquid phase during operation. Arsenic, and then produce arsenic-containing intermediate products - calcium arsenate and calcium arsenite, these intermediate products are usually processed by acid hydrolysis, such as the English literature "TFujita, R Taguchi, E Shibata, T Nakamura. Preparation of an As(V) solution for scorodite synthesis and a proposal for an integrated As fixation process in aZn refinery: Hydrometallurgy [J]. In / or calcium arsenite, the calcium in calcium arsenite is precipitated to generate calcium sulfate, but the arsenic content in the calcium sulfate produced by this method is as high as 3.2wt%, and the calcium sulfate with high arsenic content cannot be directly used for secondary application, and it is usually piled up or Landfill treatment, stacking or burying a large amount of calcium sulfate with high arsenic content will cause secondary pollution

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  • A method for acid hydrolysis of calcium arsenate and/or calcium arsenite
  • A method for acid hydrolysis of calcium arsenate and/or calcium arsenite
  • A method for acid hydrolysis of calcium arsenate and/or calcium arsenite

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Embodiment approach

[0042] In the present invention, as another embodiment, the step (1) is preferably specifically:

[0043] adding calcium arsenate and / or calcium arsenite to sulfuric acid solution for metathesis reaction, adding sulfuric acid solution during the reaction to maintain the pH value of the reaction at less than or equal to 5.0;

[0044] The pH value of the sulfuric acid solution is less than or equal to 5.0.

[0045] In the present invention, calcium arsenate and / or calcium arsenite are added into sulfuric acid solution to perform metathesis reaction, and sulfuric acid solution is added during the reaction to maintain the pH value of the reaction at less than or equal to 5.0. In the present invention, the pH value of the sulfuric acid solution is less than or equal to 5.0, preferably 0.5-4.

[0046] In the present invention, calcium arsenate and / or calcium arsenite is preferably mixed with water, prepared into a slurry and then added to the sulfuric acid solution, and the content o...

Embodiment 1

[0058] Using lime to reduce arsenic-containing wastewater (H 2 SO 4 : 25g / L; As(III): 6g / L) adjusted to pH 2.0, solid-liquid separation to obtain gypsum, continue to add lime to the filtrate to pH 11.0, solid-liquid separation, to obtain a mixture containing calcium arsenite.

[0059] Add 30mL of deionized water to 30g of the mixture containing calcium arsenite, stir until a slurry is formed, slowly add the slurry dropwise into 150ml of nitric acid solution using a peristaltic pump under mechanical stirring, add nitric acid to dissolve the calcium arsenite and stabilize the pH to 1.6, and sodium sulfate was added dropwise to the nitric acid solution, and the pH of the reaction system was maintained at 3.0. After the dropwise addition was completed, the stirring was continued for 0.5 hours, and the solid and liquid were separated to obtain calcium sulfate precipitate and arsenic-containing solution.

[0060] Gained calcium sulfate is analyzed using X-ray diffraction pattern, a...

Embodiment 2

[0063] Using lime to reduce arsenic-containing wastewater (H 2 SO 4 : 10g / L; As (V): 2g / L) adjusted to pH 2.0, solid-liquid separation to obtain gypsum, continue to add lime to the filtrate to pH 11.0, solid-liquid separation, to obtain a mixture containing calcium arsenate.

[0064] Add 30ml of deionized water to 30g of calcium arsenate-containing mixture, stir until a slurry is formed, slowly add the slurry dropwise to 150ml of sulfuric acid solution with pH 1.6 under mechanical stirring, and add dropwise to the sulfuric acid solution Sulfuric acid solution to maintain the pH of the reaction system at 2.6, continue stirring for 0.5 hours after the dropwise addition, and separate solid and liquid to obtain calcium sulfate precipitate and arsenic-containing solution.

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Abstract

The invention provides an acid hydrolysis method of calcium arsenate and / or calcium arsenite. The method comprises the following steps: (1) carrying out double decomposition reaction between calcium arsenate and / or calcium arsenite and a compound containing sulfate radicals in a solution to obtain a mixed system, wherein the pH value of the calcium arsenate and / or the calcium arsenite during the double decomposition reaction is less than or equal to 5.0; (2) carrying out solid-liquid separation of the mixed system to obtain calcium sulfate and an arsenic-containing solution. According to the acid hydrolysis method provided by the invention, the calcium sulfate is produced under a condition that the pH value of the calcium arsenate and / or the calcium arsenite is less than or equal to 5.0, so that a very small amount of arsenic can be embedded in to a calcium sulfate crystal lattice, and the calcium sulfate with low arsenic content can be obtained. An embodiment proves that the arsenic content in the calcium sulfate obtained by adopting the acid hydrolysis method is low to about 0.05 percent by weight, and the calcium sulfate can be used as a cement additive.

Description

technical field [0001] The invention relates to the technical field of waste treatment, in particular to an acid hydrolysis method of calcium arsenate and / or calcium arsenite. Background technique [0002] Arsenic is a toxic element that mainly exists in the form of sulfide and is associated with other metals such as: gold, copper, lead, nickel, cobalt, zinc, etc. A large amount of arsenic sulfide slag and high (low) arsenic wastewater will be produced. The arsenic in these arsenic sulfide residues and arsenic-containing wastewater must be removed with stable compounds. Therefore, the arsenic removal and fixation technology in the field of non-ferrous metal smelting research projects has always been a research hotspot. [0003] At present, the treatment technologies for arsenic sulfide slag mainly include: arsenic sulfide to arsenic trioxide technology, arsenic sulfide to arsenate technology, arsenic sulfide slag to arsenic trichloride technology, high temperature and high ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F11/46C04B22/14
CPCC01F11/46C01P2002/54C01P2002/72C01P2004/03C04B22/143
Inventor 贾永锋马旭王少锋
Owner SHENYANG INST OF APPL ECOLOGY CHINESE ACAD OF SCI
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