Mineral soil conditioner for simultaneously repairing lead, cadmium, copper, zinc, chromium and nickel heavy metal contaminated soil as well as preparation method and application of mineral soil conditioner

Abstract

The invention discloses a mineral soil conditioner for simultaneously repairing lead, cadmium, copper, zinc, chromium and nickel heavy metal contaminated soil as well as a preparation method and application thereof. The preparation method comprises the following steps: washing the water-based drilling mud cake and rock debris, naturally air-drying, crushing and sieving to obtain mud cake and rock debris powder; adding the mud cake and the rock debris powder into the sulfydryl solution, heating, continuously stirring for at least 6 hours, and continuously adding absolute ethyl alcohol during the period to obtain a mixture; the mixture is washed with absolute ethyl alcohol, centrifuged, dried and ground, and the sulfydryl modified mud cake and rock debris soil conditioner is obtained. Mixing the mud cake and rock debris powder with lime powder, grinding and sieving to obtain a lime compounded mud cake and rock debris soil conditioner; and mixing the mud cake and rock debris powder with humic acid, adding water, stirring, drying, grinding and sieving to obtain the humic acid modified mud cake and rock debris soil conditioner. The soil conditioner prepared by the invention can realize simultaneous restoration of lead, cadmium, copper, zinc, chromium and nickel, and is high in heavy metal adsorption efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of soil conditioners, and in particular to a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, as well as a preparation method and application thereof. Background Art

[0002] Heavy metal pollution in soil is an increasingly serious environmental problem worldwide, posing a threat to ecosystems, crops and human health. When heavy metals enter the soil, they not only poison the soil ecosystem, but also enter the groundwater, are enriched by crops (plants) and enter the food chain, endangering regional ecology and human health. Therefore, the remediation of heavy metal pollution in soil is extremely important.

[0003] At present, there are two main ways to treat heavy metal pollution in soil: one is to change the existing form of heavy metals in the soil to fix its form and reduce its mobility and bioavailability; the other is to remove heavy metals from the soil so that their concentration is close to or reaches the background value. For these two approaches, commonly used remediation methods include: chemical in-situ remediation methods, physical remediation methods, biological remediation methods, combined remediation methods, etc. Chemical in-situ remediation methods mainly include soil conditioner stabilization method and leaching removal method. It adds conditioners to the soil and uses adsorption, ion exchange, precipitation, complexation and oxidation-reduction reactions to reduce the bioavailability and mobility of heavy metals, thereby achieving the remediation of heavy metal pollution. The chemical in-situ stabilization remediation method has attracted widespread attention due to its simple operation, fast processing speed, significant effect and economical and practical application.

[0004] Water-based drilling waste mainly includes mud cake and rock cuttings, which are identified as general drilling waste and do not have hazardous characteristics. The resource utilization rate of water-based drilling mud cake / rock cuttings is low. The current main treatment method is stockpiling. The resource utilization approach is mainly used to prepare road subgrade soil, bricks and stones or expanded clay. However, from the perspective of safety, production cost, and energy conservation and consumption reduction, the preparation of water-based mud and rock cuttings into road subgrade soil, bricks and stones and expanded clay is not suitable for large-scale promotion, and new resource utilization approaches need to be developed.

[0005] At present, most commonly used soil conditioner materials are prepared with clay minerals, calcium-silicon materials, montmorillonite, biochar, phosphorus-containing materials, metal oxides, etc. as raw materials, while water-based mud and rock cuttings contain bentonite, clay, shale and other materials. Among them, the main components of bentonite are montmorillonite and calcium-based montmorillonite, which have a large specific surface area and rich active functional groups and can adsorb a variety of metal ions. However, the proportion of bentonite, clay and other materials in water-based mud cake / rock cuttings is not high, and the adsorption efficiency in practical applications is not significant. It is necessary to improve the adsorption efficiency by modifying and activating the surface properties of mud / rock cuttings. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a mineral soil conditioner, preparation method and application for simultaneously repairing soil contaminated by heavy metals such as lead, cadmium, copper, zinc, chromium and nickel. The present invention loads thiol groups onto mud cakes / rock cuttings. Since thiol groups can be efficiently complexed with heavy metals such as lead and cadmium, and the rock cuttings contain a variety of active functional groups that can efficiently bind heavy metals such as copper, zinc, chromium and nickel, the mud cake / rock cuttings skeleton can provide a loading site for thiol groups, thereby realizing efficient repair of soil heavy metal pollution; humic acid carries many active functional groups, which can react with heavy metals such as cadmium to enhance the passivation ability of minerals to heavy metals such as cadmium, and the mud cake / rock cuttings skeleton can provide a mounting site for humic acid, thereby enhancing the passivation effect of heavy metals; the mud cake / rock cuttings pH is relatively high, and lime is rich in calcium content and has a high pH. Compounding rock cuttings and lime can effectively improve the pH and calcium content of acidic soils, reduce the effective state of heavy metals in acidic soils, thereby realizing the repair of soil heavy metals.

[0007] In a first aspect, the present invention provides a method for preparing a first mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, which is achieved by adopting the following technical scheme.

[0008] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0009] S1. Wash the water-based drilling mud cake and cuttings with 2-5 times the mass of deionized water, air-dry for 1-3d, crush, and pass through a 60-mesh sieve to obtain mud cake and cuttings powder;

[0010] S2. Add the mud cake and rock powder obtained in step S1 to the thiol solution, stir continuously at 60-70 ° C for at least 6 hours, and continuously add anhydrous ethanol during this period to obtain a mixture;

[0011] S3. The mixture obtained in step S2 was centrifuged at 4000-5000 rpm for 10-20 min, and then repeatedly washed and centrifuged with anhydrous ethanol to obtain a mixture;

[0012] S4. The mixture obtained in step S3 is dried at 70-80° C., ground, and passed through a 100-mesh sieve to obtain a thiol-modified mud cake and rock chip soil conditioner for simultaneously repairing neutral soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

[0013] Furthermore, in step S1, if the original mud cake and rock cuttings samples are used, they are first crushed, then passed through a 2 mm sieve, and then washed with 2-5 times the mass of deionized water, stirring continuously during washing for at least 5 minutes.

[0014] Furthermore, in step S2, the thiol solution is a mixed solution of 3-mercaptopropyltrimethoxysilane and anhydrous ethanol, and the volume ratio of 3-mercaptopropyltrimethoxysilane to anhydrous ethanol is 1:7-1:9; the mass volume ratio of mud cake and rock cuttings powder to thiol solution is 1-4g / ml.

[0015] Furthermore, in step S2, the mass volume ratio of the mud cake and rock cuttings powder to the anhydrous ethanol is 1-4 g / ml, and the anhydrous ethanol liquid level always covers the mud cake and rock cuttings powder.

[0016] In a second aspect, the present invention provides a second method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, which is achieved by adopting the following technical scheme.

[0017] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0018] a. Wash the water-based drilling mud cake and cuttings with 2-5 times the mass of deionized water, air-dry for 1-3 days, crush, and pass through a 60-mesh sieve to obtain mud cake and cuttings powder;

[0019] b. The mud cake and rock powder obtained in step a are mixed with lime powder, ground, and repeatedly passed through a 100-mesh sieve 3-5 times to obtain a lime-compounded mud cake and rock soil conditioner for simultaneously repairing acidic soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

[0020] Furthermore, in step a, if the original mud cake and rock cuttings samples are used, they are first crushed, then passed through a 2 mm sieve, and then washed with 2-5 times the mass of deionized water, stirring continuously during washing for at least 5 minutes.

[0021] Furthermore, in step b, the mass ratio of mud cake and rock chip powder to lime powder is 9:1-12:1.

[0022] In a third aspect, the present invention provides a third method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, which is achieved by adopting the following technical scheme.

[0023] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0024] Ⅰ. Wash the water-based drilling mud cake and rock cuttings with 2-5 times the mass of deionized water, air-dry for 1-3 days, crush, and pass through a 60-mesh sieve to obtain mud cake and rock cutting powder;

[0025] Ⅱ. Mix the mud cake and rock powder obtained in step Ⅰ with humic acid, add water, and stir well to obtain a mixture;

[0026] III. The mixture obtained in step II is dried at 70-80°C, ground, and sieved through a 100-mesh sieve to obtain a humic acid-modified mud cake and rock chip soil conditioner for simultaneously repairing alkaline soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

[0027] Furthermore, in step I, if the original mud cake and rock cuttings samples are used, they are first crushed, then passed through a 2 mm sieve, and then washed with 2-5 times the mass of deionized water, stirring continuously during washing for at least 5 minutes.

[0028] Furthermore, in step II, the mass ratio of mud cake and rock cuttings powder to humic acid is 3:1-7:1.

[0029] In a fourth aspect, the present invention provides a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, which is achieved by adopting the following technical scheme.

[0030] The mineral soil conditioner prepared by the preparation method can simultaneously repair soil contaminated by heavy metals such as lead, cadmium, copper, zinc, chromium and nickel.

[0031] In a fifth aspect, the present invention provides the use of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, which is achieved by adopting the following technical scheme.

[0032] The application of the above-mentioned mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel in repairing soil contaminated by heavy metals of cadmium, copper, zinc, chromium and nickel.

[0033] This application has the following beneficial effects.

[0034] (1) The present invention loads thiol and humic acid onto mud cake / rock debris, and mixes lime with mud cake / rock debris; since thiol can complex heavy metals, humic acid can react with heavy metals, and mud cake / rock debris provides a skeleton; compounding with lime can adjust soil pH, and can achieve simultaneous repair of lead, cadmium, copper, zinc, chromium, and nickel, solving the problem of low heavy metal adsorption efficiency in the prior art;

[0035] (2) During preparation, the mud cake / rock cuttings must be initially crushed and then washed to remove the salt from the material to the maximum extent. At the same time, after the mud cake / rock cuttings and the thiol solution are mixed, the longer the stirring time, the better the quality of the thiol-modified mud cake / rock cuttings soil conditioner, and the better the adsorption effect on heavy metals;

[0036] (3) The raw materials used in the present invention are by-products of industrial production, which are inexpensive and easy to obtain. Waste resources can be recycled and utilized, and the obtained products are non-toxic and have little impact on the soil environment. DETAILED DESCRIPTION

[0037] The present patent application is further described below in conjunction with embodiments.

[0038] Example 1

[0039] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0040] (1) Wash the water-based drilling mud cake / rock cuttings with 3 times the mass of deionized water, air-dry for 2 days, crush, and pass through a 60-mesh sieve to obtain mud cake / rock cuttings powder;

[0041] (2) adding the mud cake / rock cuttings powder obtained in step (1) to the thiol solution, stirring continuously at 60° C. for 6 hours, during which anhydrous ethanol is continuously added to obtain a mixture; the thiol solution is a mixed solution of 3-mercaptopropyltrimethoxysilane and anhydrous ethanol, and the volume ratio thereof is 1:8; the solid-liquid ratio (g:ml) of the thiol solution and the mud cake / rock cuttings powder is 2; the mass volume ratio of anhydrous ethanol to the mud cake / rock cuttings powder is 2g / ml, and the liquid level of anhydrous ethanol always covers the mud cake / rock cuttings powder;

[0042] (3) centrifuging the mixture obtained in step (2) at 4000 rpm for 10 min, and then repeatedly washing with anhydrous ethanol and centrifuging to obtain a mixture;

[0043] (4) drying the mixture obtained in step (3) at 70° C., grinding it, and passing it through a 100-mesh sieve to obtain a mineral-based thiol soil conditioner that can simultaneously repair neutral soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel;

[0044] (5) Add 1% of the mineral soil conditioner prepared above to the soil contaminated with heavy metals of lead, cadmium, copper, zinc, chromium and nickel, and stir evenly; add deionized water to maintain the soil moisture content at 17.5%; culture the soil, take samples on the 0th and 42nd days of culture, and let the soil samples air dry naturally. The air-dried samples were DTPA-extracted at a solid-liquid ratio of 1:2. Oscillate at a temperature of 20°C and an oscillation speed of 180r / min for 2h; separate the samples into solid and liquid, with a centrifuge speed of 4000rpm for 10min. The obtained supernatant was filtered through a 0.45μm filter membrane; the liquid was determined by ICP-OES to determine the effective content of lead, cadmium, copper, zinc, chromium and nickel, and the results were analyzed. The results are shown in Table 1.

[0045] Table 1 Changes in the available state of heavy metals in soil after adding the soil conditioner prepared in Example 1

[0046]

[0047] Example 2

[0048] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0049] (1) Wash the water-based drilling mud cake / rock cuttings with 3 times the mass of deionized water, air-dry for 2 days, crush, and pass through a 60-mesh sieve to obtain mud cake / rock cuttings powder;

[0050] (2) mixing the mud cake / rock cuttings powder and lime powder obtained in step (1), grinding, and passing through a 100-mesh sieve three times to obtain a mineral lime soil conditioner capable of simultaneously repairing acidic soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel; the mass ratio of the mud cake / rock cuttings powder to the lime powder is 10:1;

[0051] (3) Add 1% of the mineral soil conditioner prepared above to the soil contaminated with heavy metals of lead, cadmium, copper, zinc, chromium and nickel, and stir evenly; add deionized water to maintain the soil moisture content at 17.5%; culture the soil, take samples on the 0th and 42nd days of culture, and let the soil samples air dry naturally. Then, the air-dried samples were DTPA-extracted at a solid-liquid ratio of 1:2. Oscillate at a temperature of 20°C and an oscillation speed of 180r / min for 2h; separate the sample into solid and liquid, with a centrifuge speed of 4000rpm for 10min. The obtained supernatant was filtered through a 0.45μm filter membrane; the liquid was determined for the content of lead, cadmium, copper, zinc, chromium and nickel using ICP-OES, and the results were analyzed. The results are shown in Table 2.

[0052] Table 2 Changes in the available state of heavy metals in soil after adding the soil conditioner prepared in Example 2

[0053]

[0054]

[0055] Example 3

[0056] The preparation method of a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel comprises the following steps:

[0057] (1) Wash the water-based drilling mud cake / rock cuttings with 3 times the mass of deionized water, air-dry for 2 days, crush, and pass through a 60-mesh sieve to obtain mud cake / rock cuttings powder;

[0058] (2) mixing the mud cake / rock cuttings powder obtained in step (1) with humic acid, adding water, and stirring thoroughly to obtain a mixture; the mass ratio of the mud cake / rock cuttings powder to the humic acid is 5:1;

[0059] (3) drying the mixture obtained in step (6) at 70° C., grinding it, and passing it through a 100-mesh sieve to obtain a mineral humic acid soil conditioner capable of simultaneously repairing alkaline soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

[0060] (4) Add 1% of the mineral soil conditioner prepared above to the soil contaminated with heavy metals of lead, cadmium, copper, zinc, chromium and nickel, and stir evenly; add deionized water to maintain the soil moisture content at 17.5%; culture the soil, take samples on the 0th and 42nd days of culture, and let the soil samples air dry naturally. Then, the air-dried samples were DTPA-extracted at a solid-liquid ratio of 1:2. Oscillate at a temperature of 20°C and an oscillation speed of 180r / min for 2h; separate the sample into solid and liquid, with a centrifuge speed of 4000rpm for 10min. The obtained supernatant was filtered through a 0.45μm filter membrane; the liquid was determined for the content of lead, cadmium, copper, zinc, chromium and nickel using ICP-OES, and the results were analyzed. The results are shown in Table 3.

[0061] Table 3 Changes in the available state of heavy metals in soil after adding the soil conditioner prepared in Example 3

[0062]

[0063] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, all equivalent changes made according to the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, characterized in that: The following steps are involved: S1. Wash the water-based drilling mud cake and cuttings with 2-5 times the mass of deionized water, air-dry for 1-3d, crush, and pass through a 60-mesh sieve to obtain mud cake and cuttings powder; S2. Add the mud cake and rock powder obtained in step S1 to the thiol solution, stir continuously at 60-70 ° C for at least 6 hours, and continuously add anhydrous ethanol during this period to obtain a mixture; S3. The mixture obtained in step S2 was centrifuged at 4000-5000 rpm for 10-20 min, and then repeatedly washed and centrifuged with anhydrous ethanol to obtain a mixture; S4. The mixture obtained in step S3 is dried at 70-80° C., ground, and passed through a 100-mesh sieve to obtain a thiol-modified mud cake and rock chip soil conditioner for simultaneously repairing neutral soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

2. The method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel according to claim 1, characterized in that: In step S1, if the original mud cake and rock cuttings samples are used, they are first crushed, then passed through a 2 mm sieve, and then washed with 2-5 times the mass of deionized water, stirring continuously during washing for at least 5 minutes.

3. The method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel according to claim 1, characterized in that: In step S2, the thiol solution is a mixed solution of 3-mercaptopropyltrimethoxysilane and anhydrous ethanol, the volume ratio of 3-mercaptopropyltrimethoxysilane to anhydrous ethanol is 1:7-1:9; the mass volume ratio of mud cake and rock cuttings powder to the thiol solution is 1-4g / ml.

4. The method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel according to claim 1, characterized in that: In step S2, the mass volume ratio of the mud cake and rock cuttings powder to the anhydrous ethanol is 1-4 g / ml, and the anhydrous ethanol liquid level always covers the mud cake and rock cuttings powder.

5. A method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, characterized in that: The following steps are involved: a. Wash the water-based drilling mud cake and cuttings with 2-5 times the mass of deionized water, air-dry for 1-3 days, crush, and pass through a 60-mesh sieve to obtain mud cake and cuttings powder; b. The mud cake and rock powder obtained in step a are mixed with lime powder, ground, and repeatedly passed through a 100-mesh sieve 3-5 times to obtain a lime-compounded mud cake and rock soil conditioner for simultaneously repairing acidic soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

6. The method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel according to claim 5, characterized in that: In step b, the mass ratio of mud cake and rock chip powder to lime powder is 9:1-12:

1.

7. A method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, characterized in that: The following steps are involved: Ⅰ. Wash the water-based drilling mud cake and rock cuttings with 2-5 times the mass of deionized water, air-dry for 1-3 days, crush, and pass through a 60-mesh sieve to obtain mud cake and rock cutting powder; Ⅱ. Mix the mud cake and rock powder obtained in step Ⅰ with humic acid, add water, and stir well to obtain a mixture; III. The mixture obtained in step II is dried at 70-80°C, ground, and sieved through a 100-mesh sieve to obtain a humic acid-modified mud cake and rock chip soil conditioner for simultaneously repairing alkaline soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium, and nickel.

8. The method for preparing a mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel according to claim 7, characterized in that: In step II, the mass ratio of mud cake and rock cuttings powder to humic acid is 3:1-7:

1.

9. A mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel, prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the mineral soil conditioner for simultaneously repairing soil contaminated by heavy metals of lead, cadmium, copper, zinc, chromium and nickel as claimed in claim 9 in repairing soil contaminated by heavy metals of cadmium, copper, zinc, chromium and nickel.

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