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Method for carrying out hydrothermal reduction on mineralized synergistic fixed arsenic

A hydrothermal and sodium sulfide technology, applied in chemical instruments and methods, arsenic sulfide, reduced water/sewage treatment, etc., can solve the problems of high leaching rate of solidified body, poor durability, low arsenic content, etc., and reduce storage space demand, reduce dissolution toxicity, and stabilize technical indicators

Active Publication Date: 2018-12-28
CENT SOUTH UNIV
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

All three methods can effectively reduce the leaching toxicity of arsenic-containing waste residues, but the cement encapsulation solidification method has disadvantages such as poor durability, high leaching rate of the solidified body, and large volume increase, while lime roasting solidification and vitrification both have high energy consumption and equipment Serious corrosion, easy to cause exhaust gas pollution and other problems, it is necessary to choose the appropriate method according to the disposal environment
Scoorite is prone to inconsistent dissolution during long-term stockpiling, and the stockpiling conditions need to be well controlled. The stability of Tushui hydroxyarsonite at higher pH is not as good as that at lower pH, and arsenite is more stable. However, the synthesis cost is high, and the content of arsenic in these three minerals is not high (~32%, ~25% and ~15% in turn), which will lead to an increase in solidified volume

Method used

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  • Method for carrying out hydrothermal reduction on mineralized synergistic fixed arsenic
  • Method for carrying out hydrothermal reduction on mineralized synergistic fixed arsenic
  • Method for carrying out hydrothermal reduction on mineralized synergistic fixed arsenic

Examples

Experimental program
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Embodiment 1

[0026] The arsenic concentration in the arsenic-containing solution is 11000 mg / L, the pH is 0.3, and ferrous sulfate, concentrated sulfuric acid, sodium hydroxide, sodium sulfide and glucose are all industrial grade reagents. Add ferrous sulfate to the arsenic-containing solution, control the molar ratio of Fe / As in the solution to 0.5 / 1, and then use a sodium sulfide solution with a concentration of 100g / L to control the molar ratio of sodium sulfide to arsenic and iron to 1.5 / 1, respectively And 1.0 / 1, while adding concentrated sulfuric acid to adjust the solution pH=4.5, react at 60℃ for 60min, after the reaction, adopt vacuum filtration method to separate liquid and solid; liquid-solid according to the ratio of water volume L to mass of composite precipitate in kg Add water to slurry at a ratio of 3~10 / 1, then add 2.0% glucose of the composite precipitate mass as a reducing agent, add the mixed slurry to a stainless steel high-pressure reactor, and pour nitrogen into the re...

Embodiment 2

[0028] The arsenic concentration in the arsenic-containing solution is 12,500 mg / L, the pH is 0.1, and ferrous sulfate, concentrated sulfuric acid, sodium hydroxide, sodium sulfide and glucose are all industrial grade reagents. Add ferrous sulfate to the arsenic-containing solution, control the molar ratio of Fe / As in the solution to 0.7 / 1, and then use a sodium sulfide solution with a concentration of 100g / L to control the molar ratio of sodium sulfide to arsenic and iron to 1.7 / 1, respectively At the same time, add concentrated sulfuric acid to adjust the pH of the solution to pH=4.0, and react at 60℃ for 60min. After the reaction, vacuum filtration is used for liquid-solid separation; the liquid-solid ratio of the water volume L to the composite precipitate mass kg Add water to slurry at a ratio of 3~10 / 1, then add 2.5% glucose of composite precipitate mass as a reducing agent, add the mixed slurry to the stainless steel high-pressure reactor, and pour nitrogen into the react...

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Abstract

The invention discloses a method for carrying out hydrothermal reduction on mineralized synergistic fixed arsenic. According to the method, ferrous sulfate is added into arsenic-bearing solution; under a required pH value, sodium sulfate is added to precipitate an arsenic sulfide-ferrous sulfide composite precipitate; the compound precipitate and a reducing agent are made into size by using waterand then added into a high-pressure reaction kettle; and the temperature is controlled to carry out reaction for a certain time so as to ensure that the compound precipitate is converted into a solidarsenic product with a mineral crystal form, so that the aim of reducing solid arsenic product dissolution toxicity is finally realized. According to the method, the synergistic fixing of arsenic is realized through two processes: vulcanization co-precipitation and hydrothermal reaction mineralization, so that the double aims of improving the arsenic content in solid arsenic products and reducingthe arsenic dissolution toxicity are achieved. The method has the advantages of being low in dissolution toxicity, small in solid arsenic product mass and stable in technical index.

Description

Technical field [0001] The invention relates to the treatment process of an arsenic-containing solution in the field of environmental protection, in particular to a method for synergistically fixing arsenic by hydrothermal reduction mineralization. Background technique [0002] Arsenic is a metal-like element widely found in nature. The element symbol is As, and the element abundance in the crust is 5×10 -4 %. Elemental arsenic is insoluble in water, soluble in nitric acid and aqua regia, and is easily oxidized in humid air. Elemental arsenic has three allotropes: gray arsenic, black arsenic and yellow arsenic. Its compound, arsenic trioxide, is called arsenic, which is a very toxic substance. There are more than 300 kinds of minerals in nature, arsenic is mainly realgar As 2 S 2 , Orpiment As 2 S 3 , Arsenopyrite FeAsS and arsenopyrite ((Cu, Ag, Fe, Zn) 12 As 4 S 13 ) Exists in the form of sulfide minerals, and a small part of arsenic also exists in the form of oxides and eleme...

Claims

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Application Information

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IPC IPC(8): C02F1/52C02F1/70C01G49/12C01G28/00E21C41/32E21F15/00C02F101/10
CPCC01G28/008C01G49/12C01P2002/72C01P2004/03C02F1/5236C02F1/70C02F2101/103E21C41/32E21F15/005
Inventor 刘伟锋张杜超陈霖杨天足贾锐胡斌
Owner CENT SOUTH UNIV
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