A kind of solidifying agent for heavy metal polluted soil and its preparation method

A technology of heavy metal polluted soil and curing agent, applied in the field of environmental engineering, can solve the problems of complex preparation conditions, curing effect depending on the amount of cement added, curing effect depending on the added amount, etc. , The effect of improving the strength of the gelling reaction

Inactive Publication Date: 2017-01-11
INST OF ROCK & SOIL MECHANICS CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This kind of curing agent generally uses cement, and the curing effect depends more on the amount of cement added, the cost is difficult to control, and the long-term stability is poor; Chinese Patent Publication No. CN201310493630.2, published on October 18, 2013, the invention name is hexavalent chromium contaminated soil According to the rinsing method, 0.21-0.82mol / L hydrochloric acid and contaminated soil are stirred according to the mass ratio of 5:1-10:1, and the supernatant is drawn out after standing, and the supernatant is added to the reducing agent under acidic conditions Iron powder or sodium metabisulfite or a mixture of the two in any ratio, the addition amount is 59-68g per kg soil, the hexavalent chromium in the eluent is reduced to trivalent chromium, and solid alkali is added to precipitate the trivalent chromium to achieve separation
This solidification method solidifies heavy metals of a single type, complex operation, poor controllability, and high risk of secondary pollution; Chinese Patent Publication No. CN201210355258.4, published on September 21, 2012, and the name of the invention is a kind of alkaline chromium-contaminated soil Microorganism restoration method, this method is to repair bacterial strain with Pseudomonas saccharolyticum Pseudochrobactrumsaccharolyticum LY10, with 10 7 -10 8 cells mL -1 The inoculum concentration is the bacterial inoculum concentration, and the bacterial liquid is added according to the ratio of soil to bacterial liquid mass volume ratio (g:mL) of 1:3, cultured at 28°C, and the medium is replenished every 5 days to maintain the growth and metabolic activity of the bacterial cells ; After 22 days of remediation, the removal rate of Cr(VI) in the soil reached 95.9%, and the content of exchangeable chromium was significantly reduced.
This curing method cures a single type of heavy metal, and the repair cycle is long, resulting in low repair efficiency and high cost
[0004]Cement is commonly used in the existing curing agent for heavy metal contaminated soil. The method of solidifying heavy metals is relatively single, the operation is complicated, and the controllability is poor, resulting in low efficiency of solidification, stabilization and restoration of heavy metal-contaminated soil, high secondary pollution and environmental risks, and high cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment example 1

[0026] Select phosphate rock with a phosphorus grade of 32%, wash the phosphate rock with tap water, and then dry it at 105°C. Use a ball mill to grind the phosphate rock and pass it through a 100-mesh sieve. Carbide slag was dried at 105°C, ball milled and passed through a 100-mesh sieve. Select Al 2 o 3 + SiO 2 For the water-quenched slag with a content of 40%, the water-quenched slag was washed with tap water, dried at 105°C, ball milled and passed through a 100-mesh sieve. Weigh 100kg of processed phosphate rock, 100kg of water-quenched slag, and 20kg of calcium carbide slag, mix them uniformly to form a mixture, check the pH value of the mixture, it is 8.7, add solid powder NaOH to adjust the pH of the mixture to 10, mix uniformly to form a curing agent . The addition amount of the curing agent is 10%-30% of the mass of the polluted soil.

Embodiment example 2

[0028] Select phosphate rock with a phosphorus grade of 35%, wash the phosphate rock with tap water, and then dry it at 105°C. Use a ball mill to grind the phosphate rock and pass it through a 100-mesh sieve. Carbide slag was dried at 105°C, ball milled and passed through a 100-mesh sieve. Select Al 2 o 3 + SiO 2 The water-quenched slag with a content of 38% is washed with tap water, dried at 105°C, ball-milled and passed through a 100-mesh sieve. Weigh 200kg of the treated phosphate rock, 200kg of water-quenched slag, and 40kg of carbide slag, respectively, and mix the mixture evenly. The pH of the mixture is detected to be 11. The addition amount of the curing agent is 10%-30% of the mass of the polluted soil.

Embodiment example 3

[0030] Select phosphate rock with a phosphorus grade of 30%, wash the phosphate rock with tap water, and then dry it at 105°C. Use a ball mill to grind the phosphate rock and pass it through a 100-mesh sieve. Carbide slag was dried at 105°C, ball milled and passed through a 100-mesh sieve. Select Al 2 o 3 + SiO 2 Water-quenched slag with a content of 44%, the water-quenched slag was washed with tap water, dried at 105°C, ball milled and passed through a 100-mesh sieve. Weigh 50kg of processed phosphate rock, 50kg of water quenching slag, and 10kg of carbide slag, mix the mixture uniformly, check the pH value of the mixture, it is 9.2, add solid powder NaOH to adjust the pH of the mixture to 12, and mix uniformly to form a curing agent. The addition amount of the curing agent is 10%-30% of the mass of the polluted soil.

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PUM

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Abstract

The invention discloses a heavy metal polluted soil curing agent and a preparation method thereof, and belongs to the technical field of environmental engineering. The curing agent is prepared from phosphate ore, carbide slags and water-quenched slags according to the mass ratio of 5:5:1. According to the preparation method, the phosphate ore and the water-quenched slags are subjected to water washing and ball milling for pretreatment, so that soluble salts in the phosphate ore and the water-quenched slags are effectively removed, i.e., the gelation reaction intensity is improved; phosphorus in the phosphate ore and a large quantity of heavy metal elements can form insoluble substances, so that the stabilization of the heavy metal is realized; and the carbide slags can be used for exciting activating oxides in the phosphate ore and the water-quenched slags, so that the curing of polluted soil can be realized due to the generation of silicon-aluminum-based gelation. Thus, the strength of the polluted soil is improved; and the heavy metal pollutants are wrapped and absorbed so as to be unable to move. The solid wastes are taken as main raw materials of the curing agent, so that the curing stabilization of the heavy metal polluted soil is realized by utilizing the self-chemical properties and the mutual activity excitation of the solid wastes. The curing agent has the characteristics of being free of secondary pollution, low in cost, convenient to prepare, high in resource utilization rate and the like.

Description

technical field [0001] The invention discloses a solidifying agent for heavy metal polluted soil and a preparation method thereof, belonging to the technical field of environmental engineering. Background technique [0002] According to the National Soil Pollution Survey Bulletin, the main type of soil pollution in my country is inorganic type, and the over-standard rates of 8 heavy metal pollutants including cadmium, mercury, arsenic, copper, lead, chromium, zinc and nickel are 7.0% and 1.6% respectively. , 2.7%, 2.1%, 1.5%, 1.1%, 0.9%, 4.8%. With the acceleration of urbanization and industrialization in our country, more and more land is polluted by heavy metals; the strategic layout of cities has been readjusted, and a large number of heavy metal-polluted sites are in urgent need of treatment. Soil heavy metal pollution has the characteristics of concealment, hysteresis, and long-term nature, making it difficult to repair. When heavy metals in the soil accumulate to a ce...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K17/08
Inventor 薛强李江山王平陈亿军
Owner INST OF ROCK & SOIL MECHANICS CHINESE ACAD OF SCI
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