Method for repairing polluted soil through low-temperature thermal desorption with chemical drip washing

A technology of chemical leaching and mercury pollution, which is applied in the restoration of polluted soil, etc., can solve the problems of low efficiency of leaching and repair, high energy consumption of heat treatment, and small soil damage, so as to reduce soil structure damage and improve leaching. Efficiency, effective treatment effect

Active Publication Date: 2017-11-28
AEROSPACE KAITIAN ENVIRONMENTAL TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Aiming at the defects in the heat treatment and leaching repair methods of mercury-contaminated soil in the prior art, the purpose of the present invention is to provide a combination of thermal decomposition technology and medicament leaching technology to realize multiple valence in mercury-contaminated soil. It is a method for remediating mercury-contaminated soil with high efficiency, low mercury residue, less damage to soil, and low cost. After remediation, the removal rate of mercury in soil can reach more than 95%, which solves the problem of heat treatment of general mercury-contaminated soil. The problem of high consumption and low efficiency of rinsing and repairing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] The mercury-contaminated soil left over from the relocation of a chemical factory in Hunan was taken. The average mercury content in the soil was 120 mg / kg. The soil was air-dried and crushed for later use. Configure each eluent separately, in which the concentration of citric acid in the mixed solution containing organic acid, iodine salt and chloride salt is 1moL / L, the concentration of potassium iodide is 0.1moL / L, the concentration of calcium chloride is 0.3moL / L, and the concentration of sulfide salt is And the sodium sulfide mass percent concentration in the sodium hydroxide solution is 5%, and the add-on of sodium hydroxide is 1.5% of the sodium sulfide consumption. Weigh 500 g of the pretreated soil and put it into a heat treatment device for heat treatment, set the treatment temperature to 350° C., and the treatment time to 30 minutes. The heat-treated soil is unearthed from the discharge port, the mercury in the tail gas is condensed and recovered, and then th...

Embodiment 2

[0052] Take the same soil as in Example 1, and after the same air-drying and crushing treatment, configure the same eluents as in Example 1 respectively. Weigh 500 g of the pretreated soil and put it into a heat treatment device, and heat treatment is performed under the conditions that the treatment temperature is set at 350° C. and the treatment time is 20, 30, and 40 minutes, respectively. After the heat-treated soil was cooled to normal temperature, the same leaching treatment as in Example 1 was carried out. After air-drying, the soil mercury content was measured to be 2.13mg / kg, 1.15mg / kg, and 1.01mg / kg respectively. The removal rates of mercury in the soil were respectively 98.23%, 99.04%, 99.16%. When the treatment time was 30 and 40 minutes, the mercury content in the soil was lower than the third grade standard value (1.5mg / kg) of "Soil Environmental Quality Standard" (GB15618-1995).

Embodiment 3

[0054]Take the same soil as in Example 1, and after the same air-drying and crushing treatment, configure the same eluents as in Example 1 respectively. Weigh 500 g of the pretreated soil and put it into a heat treatment device, and heat treatment is performed under the conditions that the treatment time is set to 30 minutes and the treatment temperature is 250, 300, and 350° C. respectively. After the heat-treated soil was cooled to normal temperature, the same leaching treatment as in Example 1 was carried out. After the air-drying treatment, the mercury content in the soil was measured to be 1.96mg / kg, 1.05mg / kg, and 0.94mg / kg. The removal rates of mercury in the soil were respectively 98.37%, 99.13%, 99.22%. When the treatment temperature was 300 and 350℃, the mercury content in the soil was lower than the third grade standard value (1.5mg / kg) of "Soil Environmental Quality Standard" (GB15618-1995).

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Abstract

The invention discloses a method for repairing polluted soil through low-temperature thermal desorption with chemical drip washing. The method comprises the following steps: firstly, performing low-temperature thermal desorption treatment on mercury polluted soil so as to remove metal mercury, organic combined mercury and a part of inorganic combined mercury with a low melting point in the soil; secondly, performing drip washing with a mixed liquid containing organic acids, iodate and chlorine salts so as to remove mercuric oxide with a high melting point; and finally performing drip washing on mercuric sulfide with a high melting point with a mixed liquid of sodium sulfide and sodium hydroxide. By adopting the method, efficient removal of mercury of multiple valence states in mercury polluted soil can be achieved, a small amount of mercury is retained, the removal rate of mercury is up to 95% or greater, secondary pollution to the environment is avoided, and the cost is low.

Description

technical field [0001] The invention relates to a method for repairing mercury-contaminated soil, in particular to a method for repairing mercury-contaminated soil through low-temperature thermal desorption combined with leaching, and belongs to the technical field of heavy metal soil treatment. Background technique [0002] In recent years, with the rapid development of industry and agriculture, a large amount of mercury has been released in the process of production and use, making the soil polluted by mercury more and more serious. The main sources of soil mercury pollution are atmospheric deposition, sewage irrigation, industrial pollution sources (coal-burning, chlor-alkali industry, battery factory, smelting, papermaking and other industries), agricultural pollution sources (use of pesticides and fertilizers), mercury-containing waste (thermometers, waste battery, etc.) mishandled, etc. Mercury and its compounds in the soil can enter the human body through the food ch...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/02B09C1/06B09C1/08
CPCB09C1/02B09C1/06B09C1/08
Inventor 邵乐史学峰韩凤刘晓月
Owner AEROSPACE KAITIAN ENVIRONMENTAL TECH CO LTD
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