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A method for synergistic arsenic fixation by hydrothermal reduction and mineralization

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: 2021-03-09
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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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  • A method for synergistic arsenic fixation by hydrothermal reduction and mineralization
  • A method for synergistic arsenic fixation by hydrothermal reduction and mineralization
  • A method for synergistic arsenic fixation by hydrothermal reduction and mineralization

Examples

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Embodiment 1

[0026]The arsenic concentration in the arsenic-containing solution is 11000mg / L, the pH is 0.3, 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 ratios of sodium sulfide, arsenic and iron to 1.5 / 1 respectively and 1.0 / 1, add concentrated sulfuric acid to adjust the pH of the solution to 4.5, and react at a temperature of 60°C for 60 minutes. After the reaction, vacuum filtration is used to separate the liquid from the solid; Slurry with water at a ratio of 3 to 10 / 1, then add glucose with a weight of 2.0% of the composite sediment as a reducing agent, add the mixed slurry into a stainless steel high-pressure reactor, and feed nitrogen into the reactor to discharge residual air. Ventilate for 2 minute...

Embodiment 2

[0028] The concentration of arsenic in the solution containing arsenic is 12500 mg / L, the pH is 0.1, 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 ratios of sodium sulfide, arsenic and iron to 1.7 / 1 respectively and 1.0 / 1, add concentrated sulfuric acid to adjust the pH of the solution to 4.0, react at a temperature of 60°C for 60 minutes, and separate the liquid and solid by vacuum filtration after the reaction; Slurry with water at a ratio of 3 to 10 / 1, then add glucose with a weight of 2.5% of the composite sediment as a reducing agent, add the mixed slurry into a stainless steel high-pressure reactor, and feed nitrogen into the reactor to discharge the residual air. Ventilate for 2 minutes at ...

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Abstract

A method for synergistic arsenic fixation by hydrothermal reduction mineralization, adding ferrous sulfate to the arsenic-containing solution, adding sodium sulfide at a required pH value to precipitate arsenic sulfide-ferrous sulfide composite precipitate, the composite precipitate and reduction After the agent is mixed with water, it is added to the high-pressure reactor, and the temperature is controlled for a certain period of time to convert the composite precipitate into an arsenic-fixed product with a mineral crystal form, and finally achieve the purpose of reducing the dissolution toxicity of the arsenic-fixed product. The essence of the present invention is to realize the synergistic solidification of arsenic by using two processes of sulfide co-precipitation and hydrothermal reduction mineralization, so as to achieve the dual purposes of increasing the arsenic content in the arsenic-fixed product and reducing the toxicity of arsenic dissolution. The invention has the advantages of low dissolution toxicity, small quality of arsenic-fixed product, stable technical index and the like.

Description

technical field [0001] The invention relates to the treatment process of 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 metalloid element that widely exists in nature. The element symbol is As, and the element abundance in the earth's 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 of gray arsenic, black arsenic and yellow arsenic, and its compound arsenic trioxide is called arsenic, which is a highly 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 arsenite ((Cu, Ag, Fe, Zn) 12 As 4 S 13 ) and other sulfide minerals, and a small amount of arsenic also exists in the form of o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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