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Method for reducing leaching toxicity of acidic chromium (VI) contaminated site through RPSCP process

A site and process technology, applied in the restoration of polluted soil and other directions, can solve problems such as cement slurry solidification, trivalent chromium leaching, and cost increase, and achieve the effects of easy purchase, reduction of leaching rate, and control of production costs.

Inactive Publication Date: 2020-06-23
环保桥(湖南)生态环境工程股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] 2. During site restoration, the reduced trivalent chromium in the soil was not chemically precipitated, but directly physically solidified
After the reduction of hexavalent chromium in the current chromium pollution remediation technology, most of the curing agents are directly added to directly cure the trivalent chromium and its soil. This curing will not leach trivalent chromium under dry conditions, but if there are external factors Such as acid rain, the temperature makes the solidified body rupture, which will directly lead to the leaching of free trivalent chromium
In addition, other chemicals are added to the original soil during restoration, which will affect the solidification of the cement slurry and increase the cost

Method used

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  • Method for reducing leaching toxicity of acidic chromium (VI) contaminated site through RPSCP process
  • Method for reducing leaching toxicity of acidic chromium (VI) contaminated site through RPSCP process
  • Method for reducing leaching toxicity of acidic chromium (VI) contaminated site through RPSCP process

Examples

Experimental program
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Effect test

Embodiment 1

[0043] Taking the remediation of hexavalent chromium-contaminated soil at the original site of a chromium salt factory in Changsha as an example, the pH of the contaminated soil is 5.1, and the hexavalent chromium content is 468 mg / kg, exceeding the "Soil Environmental Quality Construction Land Soil Pollution Risk Control Standard (Trial)" (GB 36600 -2018) The risk control value of chromium (hexavalent) for the second type of land use is about 5 times. Take the soil to be repaired and transport it to the designated repair area, clean the soil, crush it, sieve it, add ferrous sulfate heptahydrate 6% of the soil mass and mix it evenly with the soil, add water until the soil moisture content is 45%, and then maintain it for 7 days, then add Calcium hydroxide with 12% of the soil quality was mixed evenly with the soil, and the soil moisture content was maintained at 45% for 7 days, and sodium phosphate with 3% of the soil quality was added to mix with the soil, and the soil moistur...

Embodiment 2

[0050] Taking the remediation of chromium-contaminated soil at the original site of an electroplating factory in Foshan as an example, the pH of the contaminated soil is 5.3, and the content of hexavalent chromium is 961mg / kg, which exceeds the "Soil Environmental Quality Construction Land Soil Pollution Risk Control Standard (Trial)" (GB 36600-2018 ) The risk control value of chromium (hexavalent) for the second type of land use is 11 times. Take the soil to be repaired and transport it to the designated repair area. After the soil is crushed and sieved, add ferrous sulfate heptahydrate with a soil mass of 7% and mix with the soil evenly. Add water until the soil moisture content is 50% and maintain it for 9 days. Calcium hydroxide with 14% of the soil mass is mixed evenly with the soil, and the soil moisture content is maintained at 50% for 9 days. Add sodium phosphate with a soil mass of 3% and mixed with the soil, and the soil moisture content is maintained at 50% for 9 day...

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Abstract

The invention relates to the field of soil remediation, and specifically discloses a method for reducing leaching toxicity of an acidic chromium (VI) contaminated site through an R-P-S-C-P process. The method comprises the steps of applying ferrous sulfate for reduction, applying calcium hydroxide for precipitation, applying sodium phosphate for stabilization, applying cement for solidification, and carrying out precaution by coating a cured body by asphalt. The repaired chromium polluted soil can be safely reused. The method has the advantages that the cost is low, the restoration is efficient, secondary pollution is avoided, hexavalent chromium can be reduced, trivalent chromium can be precipitated, the chromium precipitate can be stabilized and fixed, and the leaching toxicity of the chromium (VI) can be prevented.

Description

technical field [0001] The present invention relates to the field of site soil remediation, in particular to a method for reducing the leaching toxicity of acidic chromium (VI) polluted sites through the R-P-S-C-P process, comprising applying ferrous sulfate for reduction (Reduction) - applying calcium hydroxide for precipitation (Precipitation) - applying Sodium phosphate for stabilization (Stabilization) - application of cement for curing (Curing) - application of asphalt for prevention (Precaution). Background technique [0002] Chromium is a common metal pollutant in the natural environment. It is one of the five heavy metals monitored in my country's "Soil Pollution Prevention and Control Action Plan" and one of the top 20 toxic substances prioritized by the US Superfund. Heavy metal chromium mainly has two valence states, and the toxicity of different valence states is also inconsistent. Trivalent chromium is less toxic and has less impact on the environment. Hexavale...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B09C1/08B09C1/00
CPCB09C1/00B09C1/08
Inventor 袁海伟吴霄霄唐守寅熊琪胡露田一君董帅厅
Owner 环保桥(湖南)生态环境工程股份有限公司