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

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...

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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