Soil remediation agent suitable for heavy metal polluted mining wasteland and preparation method of soil remediation agent

Abstract

The invention discloses a soil remediation agent suitable for heavy metal polluted mining wasteland and a preparation method of the soil remediation agent. The soil remediation agent comprises the following raw material components in percentage by mass: 20-40% of fly ash; 5-15% of slag; 5-20% of steel slag; 20-40% of red mud; 2-5% of gypsum; 8 to 10 percent of montmorillonite; 3-4% of an exciting agent; and 2-3% of a stabilizer. The powder prepared from industrial waste is selected and doped into the heavy metal polluted mine soil, heavy metal in the soil is solidified, the leaching toxicity of the heavy metal is reduced, meanwhile, the pH value of the soil can be adjusted, and after the heavy metal polluted mine soil is treated by the prepared heavy metal polluted mine soil remediation agent, the use of a site can be restored; the problem of insufficient land is solved, and site resource recycling is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of restoration of contaminated soil, and in particular relates to a soil repair agent suitable for abandoned mines contaminated by heavy metals and a preparation method thereof. Background Art

[0002] The development and utilization of mineral resources is the largest organized human activity to date that has changed the earth's surface landscape and destroyed the surface ecosystem. Long-term mining in mining areas has not only greatly changed the original landscape ecological environment, but also led to ecological degradation and environmental pollution in mining areas. After a large amount of mineral resources have been mined, large-scale mine wastelands have been left behind, causing many environmental and geological problems. The heavy metal pollutants in mine wastelands have a particularly serious impact on the surrounding environment, causing harm to the soil, water, plants, etc. in the mining area.

[0003] The main characteristics of abandoned mines are: first, poor physical structure and poor water and fertilizer retention capacity; second, extreme barrenness or nutrient imbalance; third, excessive heavy metal content; fourth, extreme pH value; fifth, severe drought or physiological drought. Therefore, abandoned mines not only lose the characteristics of natural topsoil, but also have many extreme physical and chemical properties, making it difficult to repair abandoned mines contaminated by heavy metals. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a soil remediation agent suitable for heavy metal contaminated mine wastes and a preparation method thereof in view of the deficiencies existing in the prior art. The soil remediation agent uses industrial waste slag as raw materials and solidifies heavy metals in situ through chemical reactions. The soil remediation agent can be applied to heavy metal contaminated soils in mine wastes with different heavy metal element pollution and different pollution degrees to reduce the leaching concentration of heavy metals.

[0005] The present invention provides a soil remediation agent suitable for heavy metal polluted mine wasteland, and its raw material components and mass percentages are as follows:

[0006]

[0007]

[0008] According to the above scheme, the SiO2 content in the fly ash is 40-60%, the Al2O3 content is 20-30%, and the particle size is 0.075-0.15 mm.

[0009] According to the above scheme, the slag is granulated blast furnace slag, wherein the SiO2 content is 30-40%, the Al2O3 content is 10-20%, the CaO content is 30-40%, and the particle size is 0.08-0.3mm.

[0010] According to the above solution, the steel slag is electric furnace steel slag.

[0011] According to the above scheme, the red mud is industrial solid waste discharged when the aluminum industry extracts alumina, and the moisture content is 25-35%. Fly ash, slag and red mud are all silicon-aluminum-based industrial waste residues.

[0012] According to the above scheme, the gypsum is desulfurized gypsum.

[0013] According to the above scheme, the montmorillonite is sodium montmorillonite.

[0014] According to the above scheme, the activator is one or more combinations of sodium sulfate, sodium carbonate, sodium hydroxide, triethanolamine, water glass, calcium chloride, and polyaluminium chloride. Preferably, the activator is a mixture of sodium hydroxide, triethanolamine, water glass, calcium chloride and polyaluminium chloride in a mass ratio of 1:1:1:1:1, or a mixture of sodium sulfate, triethanolamine, water glass, calcium chloride and polyaluminium chloride in a mass ratio of 1:1:1:1:1, or a mixture of sodium carbonate, triethanolamine, water glass, calcium chloride and polyaluminium chloride in a mass ratio of 1:1:1:1:1.

[0015] According to the above scheme, the stabilizer is obtained by mixing ethylenediaminetetraacetic acid (EDTA) and diethyltriaminepentaacetic acid (DTPA) in a molar ratio of 1:1 to 2. Preferably, the stabilizer is obtained by mixing ethylenediaminetetraacetic acid and diethyltriaminepentaacetic acid in a molar ratio of 1:1 or 1:2. Since both EDTA and DTPA have multiple groups that can coordinate with metal ions, when they are mixed in a ratio of 1:1 or 1:2 and added to a system containing metal ions, the two will compete with the metal ions for coordination. When the mixture of EDTA and DTPA is applied to the soil, the active state of the metal ions can be adjusted. They can complex excessive harmful heavy metal ions (such as lead, cadmium, etc.), reduce their bioavailability, and reduce the absorption of these harmful metals by plants; at the same time, they can also appropriately regulate the existence form of trace elements such as iron, zinc, and manganese, making them more conducive to plant root absorption and utilization, promoting plant growth, and improving the chemical environment of the soil in a composite way, ensuring the ecological health of the soil and the yield and quality of crops.

[0016] Preferably, the raw material components and mass percentages of the soil remediation agent suitable for heavy metal polluted mine wastes are: 30% fly ash, 15% slag, 20% steel slag, 20% red mud, 2% gypsum, 8% montmorillonite, 3% activator, and 2% stabilizer.

[0017] Preferably, the raw material components and mass percentages of the soil remediation agent suitable for heavy metal polluted mine wastes are: 30% fly ash, 10% slag, 10% steel slag, 30% red mud, 4% gypsum, 10% montmorillonite, 4% activator, and 2% stabilizer.

[0018] Preferably, the raw material components and mass percentages of the soil remediation agent suitable for heavy metal polluted mine wastes are: 30% fly ash, 5% slag, 5% steel slag, 40% red mud, 5% gypsum, 8% montmorillonite, 4% activator, and 3% stabilizer.

[0019] The present invention also provides a method for preparing the soil remediation agent applicable to heavy metal polluted mine wasteland, and the specific steps are as follows:

[0020] 1) Weigh each raw material component according to the ratio and set aside;

[0021] 2) Grind all the raw materials together in a ball mill until the Blaine surface area is 300-500cm 2 / g, and obtain a soil remediation agent suitable for abandoned mines polluted by heavy metals.

[0022] The present invention also includes the use of the soil repair agent in repairing abandoned mine land polluted by heavy metals.

[0023] The specific method of use is: add the above soil remediation agent into the soil of the heavy metal polluted mine wasteland, mix evenly, and the amount of soil remediation agent added is 10-15% of the soil mass.

[0024] The present invention uses a large amount of red mud and fly ash. When the mass ratio is 1:1 and the total amount reaches 60-80%, the test effect is better. For severely polluted acidic heavy metal-contaminated mine wastes, the proportion of red mud can be appropriately increased to make full use of its alkalinity to adjust the soil pH value. The high alkalinity of red mud can adjust the pH value of acidic heavy metal mine wastes to make it close to neutral or weakly alkaline. The appropriate pH value is conducive to the precipitation and fixation of heavy metals in the soil, and can also improve the physical and chemical properties of the soil and create a good environment for plant growth; red mud contains a certain amount of organic matter and nutrients required for plant growth, such as calcium, silicon, potassium, phosphorus, etc.; the addition of red mud can change the microbial community structure and activity of the soil. Some microorganisms can survive and reproduce in the environment provided by red mud, and interact with heavy metals. For example, some microorganisms can adsorb and fix heavy metal ions by secreting extracellular polymers, producing biosorbents, etc., or convert heavy metals into low-toxic or non-toxic forms through biotransformation. In addition, the metabolic activities of microorganisms can also promote the decomposition of organic matter and the circulation of nutrients in the soil, further improve the soil environment, and facilitate the remediation of heavy metals.

[0025] In addition, the addition of red mud and fly ash can improve the structure of soil in heavy metal-contaminated mine wasteland. Red mud particles can fill soil pores and increase soil density, while fly ash can make the soil more loose and increase soil air permeability and water permeability. They work together to help form a good soil aggregate structure, provide favorable conditions for the growth of soil microorganisms and the development of plant roots, and are also beneficial to fix heavy metals in the soil. In addition, sodium montmorillonite is added to the system of the present invention to remove heavy metal ions through exchange and induced precipitation.

[0026] The beneficial effects of the present invention are: 1. The heavy metal content in heavy metal-contaminated mine wastes is high, and the content of heavy metals in the soil often far exceeds the soil environmental quality standards. At the same time, the soil is acidified. The present invention selects powder made from industrial waste and mixes it into the heavy metal-contaminated mine soil to solidify the heavy metals in the soil, reduce its heavy metal leaching toxicity, and adjust its pH. After the heavy metal-contaminated mine soil is treated with the heavy metal-contaminated mine soil remediation agent prepared by the present invention, the use of the site can be restored, which solves the problem of insufficient land and realizes the recycling of site resources.

[0027] 2. The heavy metal contaminated mine soil remediation agent prepared by the present invention uses a large amount of industrial waste (up to more than 80%), reduces material costs, and realizes the resource utilization of industrial waste. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0029] The fly ash used in the embodiment of the present invention has an SiO2 content of 40-60%, an Al2O3 content of 20-30%, and a particle size of 0.075-0.15 mm; the slag used is granulated blast furnace slag, in which the SiO2 content is 30-40%, the Al2O3 content is 10-20%, the CaO content is 30-40%, and the particle size is 0.08-0.3 mm; the red mud used is industrial solid waste discharged when alumina is extracted in the aluminum industry, and has a moisture content of 25-35%.

[0030] Example 1

[0031] A soil remediation agent suitable for heavy metal polluted mine wasteland, the raw material components and mass percentages of which are as follows: 30% fly ash, 15% slag, 20% electric furnace slag, 20% red mud, 2% desulfurized gypsum, 8% sodium montmorillonite, activator (sodium hydroxide, triethanolamine, water glass, calcium chloride and polyaluminium chloride in a mass ratio of 1:1:1:1:

[0032] 1 mixed) 3%, stabilizer (ethylenediaminetetraacetic acid and diethyltriaminepentaacetic acid mixed in a molar ratio of 1:1) 2%.

[0034] The specific steps of its preparation method are as follows:

[0035] 1) Weigh each raw material component according to the ratio and set aside;

[0036] 2) Grind all the raw materials together in a ball mill until the Blaine surface area is 300-500cm 2 / g, and obtain a soil remediation agent suitable for abandoned mines polluted by heavy metals.

[0037] Example 2

[0038] A soil repair agent suitable for heavy metal-contaminated mine wastelands, wherein the raw material components and mass percentages thereof are as follows: 30% fly ash, 10% slag, 10% electric furnace slag, 30% red mud, 4% desulfurized gypsum, 10% sodium montmorillonite, 4% activator (mixed with sodium sulfate, triethanolamine, water glass, calcium chloride and polyaluminium chloride in a mass ratio of 1:1:1:1:1), and 2% stabilizer (mixed with ethylenediaminetetraacetic acid and diethyltriaminepentaacetic acid in a molar ratio of 1:1).

[0040] The specific steps of its preparation method are as follows:

[0041] 1) Weigh each raw material component according to the ratio and set aside;

[0042] 2) Grind all the raw materials together in a ball mill until the Blaine surface area is 300-500cm 2 / g, and obtain a soil remediation agent suitable for abandoned mines polluted by heavy metals.

[0043] Example 3

[0044] A soil repair agent suitable for heavy metal polluted mine wasteland, the raw material components and mass percentages of which are as follows: 30% fly ash, 5% slag, 5% electric furnace slag, 40% red mud, 5% desulfurized gypsum, 8% sodium montmorillonite, 4% activator (sodium carbonate, triethanolamine, water glass, calcium chloride and polyaluminium chloride mixed in a mass ratio of 1:1:1:1:1), and 3% stabilizer (ethylenediaminetetraacetic acid and diethyltriaminepentaacetic acid mixed in a molar ratio of 1:2).

[0045] The specific steps of its preparation method are as follows:

[0046] 1) Weigh each raw material component according to the ratio and set aside;

[0047] 2) Grind all the raw materials together in a ball mill until the Blaine surface area is 300-500cm 2 / g, and obtain a soil remediation agent suitable for abandoned mines polluted by heavy metals.

[0048] Example 4

[0049] The soil remediation agent prepared in the above Examples 1-3 was added to the soil of the abandoned mine contaminated by heavy metals, and mixed evenly to obtain solidified soil. The amount of the soil remediation agent added was 10% of the mass of the soil. After curing for 7 days under standard curing conditions, the solidified soil was crushed and mixed with a leaching agent (concentrated sulfuric acid and concentrated nitric acid mixed in a mass ratio of 2:1) at a liquid-to-solid volume ratio of 20:1. The soil was analyzed according to the method of "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ 557-2010), and then oscillated in an oscillating device for 24 hours, and then filtered to determine the concentration of heavy metals in the leachate.

[0050] The test results of using the soil remediation agent prepared in Example 1 to remediate the heavy metal contaminated mine wasteland soil sample 1 are shown in Table 1.

[0051] Table 1

[0052]

[0053] The test results of using the soil remediation agent prepared in Example 2 to remediate the heavy metal contaminated mine wasteland soil sample 2 are shown in Table 2.

[0054] Table 2

[0055]

[0056] The test results of using the soil remediation agent prepared in Example 3 to remediate the heavy metal contaminated mine wasteland soil sample 3 are shown in Table 3.

[0057] Table 3

[0058]

[0059] The above test data prove that the soil remediation agent prepared in the embodiment of the present invention can not only effectively fix heavy metal ions in contaminated soil and reduce leaching toxicity, but also adjust the pH value and organic matter content of the soil, improve soil performance and soil fertility. The heavy metal concentration in the leachate after remediation meets the Class IV standard in "GB3838-2002 Surface Water Environmental Quality Standard".

[0060] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A soil remediation agent suitable for heavy metal polluted mine wasteland, characterized in that: The raw material components and mass percentages are as follows:

2. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The fly ash has an SiO2 content of 40-60%, an Al2O3 content of 20-30%, and a particle size of 0.075-0.15 mm; the slag is granulated blast furnace slag, in which the SiO2 content is 30-40%, the Al2O3 content is 10-20%, the CaO content is 30-40%, and the particle size is 0.08-0.3 mm.

3. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The steel slag is electric furnace steel slag; the red mud is industrial solid waste discharged when the aluminum industry extracts alumina, and has a water content of 25-35%.

4. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The gypsum is desulfurized gypsum.

5. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The montmorillonite is sodium montmorillonite.

6. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The activator is one or more combinations of sodium sulfate, sodium carbonate, sodium hydroxide, triethanolamine, water glass, calcium chloride and polyaluminium chloride.

7. The soil remediation agent suitable for heavy metal polluted mine wasteland according to claim 1, characterized in that: The stabilizer is obtained by mixing ethylenediaminetetraacetic acid and diethyltriaminepentaacetic acid in a molar ratio of 1:1-2.

8. A method for preparing a soil remediation agent suitable for heavy metal polluted mine wasteland according to any one of claims 1 to 7, characterized in that: The specific steps are as follows: 1) Weigh each raw material component according to the ratio and set aside; 2) Grind all the raw materials together in a ball mill until the Blaine surface area is 300-500cm 2 / g, and obtain a soil remediation agent suitable for abandoned mines polluted by heavy metals.

9. Use of the soil remediation agent suitable for heavy metal polluted mine waste land according to any one of claims 1 to 7 in remediating heavy metal polluted mine waste land.

10. The use of the soil remediation agent for heavy metal polluted mine wastes according to claim 9 in remediating heavy metal polluted mine wastes, characterized in that: The specific method of use is: add the above soil remediation agent into the soil of the heavy metal polluted mine wasteland, mix evenly, and the amount of soil remediation agent added is 10-15% of the soil mass.

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