Method for restoring soil of high-altitude abandoned mine by using longleaf thyme herb

Abstract

The invention relates to the technical field of soil remediation, in particular to a method for remediating soil of a high-altitude abandoned mine through longleaf thyme herb. The method comprises the following steps: (1) applying a pH regulator to soil, and turning over to regulate the pH of the soil to 5.7-6.5; (2) a soil conditioner is applied to the soil ploughed in the step (1), ploughing is conducted, watering is conducted once every day, and watering lasts for 10-30 days; (3) applying a compound fertilizer to the soil ploughed in the step (2), and ploughing; and (4) planting the thyme longissimum in the soil ploughed in the step (3), and applying a complex microbial inoculant. The method disclosed by the invention has a good remediation effect on the abandoned mine soil in the high-altitude area, is relatively low in cost and also has certain economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of soil remediation, and in particular to a method for remediating soil of abandoned mines at high altitudes using long-leafed bellwort. Background Art

[0002] With the acceleration of social development and industrialization, mining activities have become more frequent. Mining has led to the generation of a large number of mining wastelands, causing serious damage to the ecological environment, and thus causing a variety of natural disasters and environmental problems. For example, serious geological disasters such as landslides, soil erosion, landslides, mudslides and tiankengs caused by the destruction of surface soil and vegetation in mines, environmental problems such as water quality and air pollution, soil degradation, and biodiversity loss caused by the destruction of surface landscape vegetation, as well as the phenomenon of a large amount of land being abandoned due to mining. Therefore, how to achieve the restoration of mine soil and ecological restoration is an urgent problem that needs to be solved.

[0003] Mining causes the surface soil in the mining area to be severely compacted, with a large bulk density, low soil permeability and a large amount of coarse particles. In addition, the physical and chemical properties of the soil in the mining area are poor, the nutrients are low, and the content of toxic and harmful substances such as heavy metals in the soil is high. In addition, the surface of abandoned mines is usually exposed and hard, with a thin planting soil layer, poor soil structure and low water retention. Therefore, it is difficult for plants to survive and grow. It is difficult to achieve ecological restoration by planting plants, especially in abandoned mines in high-altitude areas. The living conditions of plants are even worse, and the survival rate of plants is low. It is difficult to rely on simple plant planting for restoration. Therefore, how to provide a soil remediation method with good effect, low cost and certain economic effect for abandoned mines in high-altitude areas is a problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of the above-mentioned prior art and provide a method for soil restoration of abandoned mines at high altitudes using long-leaved bell grass. The method has a good restoration effect on the soil of abandoned mines in high altitude areas, has low cost and also has certain economic benefits.

[0005] In order to achieve the above object, the present invention provides a method for soil remediation of high-altitude abandoned mines by using long-leaf bell grass, the method comprising:

[0006] (1) Apply pH regulator to the soil and till the soil to adjust the soil pH to 5.7-6.5;

[0007] (2) applying a soil conditioner to the soil after plowing in step (1), plowing the soil, and watering the soil once a day for 10 to 30 days;

[0008] (3) applying compound fertilizer to the soil after plowing in step (2), and plowing;

[0009] (4) planting long-leafed bellflower on the soil after plowing in step (3) and applying a composite bacterial agent;

[0010] The soil conditioner comprises modified activated carbon and modified clay-based materials, and the amount of the soil conditioner is 0.8-3.2 kg / m 2 The composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, black ball paint spot and round brown nitrogen-fixing bacteria, and the dosage of the composite bacterial agent is 10-40g / m 2 .

[0011] The present invention provides a suitable acid-base environment for subsequent steps by adjusting the pH of the soil of high-altitude abandoned mines, applying soil conditioners to adsorb and deposit heavy metals and harmful substances in the soil, and applying compound fertilizers to improve the nutritional state of the soil, so that the soil reaches a state sufficient for planting and growing long-leaf bell grass, and then by planting long-leaf bell grass adapted to the high-altitude climate, and using its special biological characteristics to cooperate with soil conditioners and compound bacterial agents, etc., so as to further absorb, enrich, fix and degrade heavy metals and pollutants, and with the cooperation of various elements, water and soil and fertility are consolidated, the growth of long-leaf bell grass is promoted, and finally the soil is repaired. In addition, the planting and maintenance costs of long-leaf bell grass are low, the ecological benefits are obvious, and the growth is rapid. It can increase the vegetation coverage of abandoned mines in a short time, achieve the effect of ecological restoration, and also have certain economic benefits. DETAILED DESCRIPTION

[0012] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0013] The present invention provides a method for remediating soil in abandoned mines at high altitudes using long-leafed bellwort, the method comprising:

[0014] (1) Apply pH regulator to the soil and till the soil to adjust the soil pH to 5.7-6.5;

[0015] (2) applying a soil conditioner to the soil after plowing in step (1), plowing the soil, and watering the soil once a day for 10 to 30 days;

[0016] (3) applying compound fertilizer to the soil after plowing in step (2), and plowing;

[0017] (4) planting long-leafed bellflower on the soil after plowing in step (3) and applying a composite bacterial agent;

[0018] The soil conditioner comprises modified activated carbon and modified clay-based materials, and the amount of the soil conditioner is 0.8-3.2 kg / m 2 The composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, black ball paint spot and round brown nitrogen-fixing bacteria, and the dosage of the composite bacterial agent is 10-40g / m 2 .

[0019] According to the present invention, the pH value of the soil in abandoned mines in high-altitude areas is adjusted, and soil conditioners and compound fertilizers are applied to improve the soil state, thereby providing a suitable environment for the planting and growth of long-leaf bellwort, and then through the special biological characteristics of long-leaf bellwort and specific bacteria to heavy metals, combined with previous soil conditioners, relying on the synergistic coordination of physical adsorption, chemical deposition and biological degradation, the content of heavy metals and pollutants in the soil is greatly reduced, the soil state is improved, the water and soil and fertility are consolidated, and the soil is repaired.

[0020] According to the present invention, before the above method is carried out, the site of the abandoned mine needs to be tidied up first to improve the soil erosion situation and facilitate the smooth progress of the subsequent steps. Preferably, the above method also includes leveling the abandoned mine site and building a drainage system before carrying out step (1). In order to obtain a better arable layer to facilitate plant growth, preferably, the site leveling includes digging out the soil at a depth of 20-40 cm, removing large-volume debris (such as branches, gravel and other debris) in the soil, breaking up large-volume soil clumps, and then backfilling them to the original place.

[0021] According to the present invention, in step (1), by applying a pH regulator to the abandoned mine soil to adjust the soil pH to 5.7-6.5, it can not only provide a suitable acid-base environment for the planting and growth of long-leaved bell grass, but also provide a suitable living environment for each bacterial species in the subsequent composite bacterial agent. At the same time, the application of the pH regulator can also prevent the loss of soil nutrients, which is conducive to consolidating soil fertility after the subsequent application of composite fertilizers. Preferably, the pH regulator is selected from one or more of lime, caustic soda, plant ash, limestone and phosphogypsum, preferably lime and / or caustic soda.

[0022] According to the present invention, in step (2), the soil conditioner can reduce the heavy metal content in the soil of abandoned mines. Watering once a day is to keep the soil at a certain water content to facilitate the soil conditioner to work. After 10-30 days, the heavy metal content in the soil can be reduced to a range that can be used for the planting and growth of long-leaved bell grass. In order to achieve better results and improve the efficiency of the soil conditioner, preferably, the mass ratio of the modified activated carbon to the modified clay-based material is 1:4-10, preferably 1:6-8, for example, it can be 1:6, 1:7, 1:7.5 and 1:8 and the range between any values ​​thereof.

[0023] Preferably, the amount of the soil conditioner is 1.6-2.4 kg / m 2 , for example, it can be 1.6 kg / m 2 , 1.8kg / m 2 , 2kg / m 2 and 2.4kg / m 2 The range between the values ​​and any values ​​in between.

[0024] According to the present invention, in step (2), the modified activated carbon and the modified clay-based material in the soil conditioner can respectively adsorb different types of heavy metals. Through the synergistic combination of the modified activated carbon and the modified clay-based material, the heavy metal content in the soil can be reduced more quickly, reducing the impact of heavy metal pollutants on plants.

[0025] According to the present invention, preferably, the method for preparing the modified activated carbon comprises: subjecting activated carbon, an aqueous nitric acid solution and an aqueous potassium permanganate solution to a contact reaction to obtain the modified activated carbon.

[0026] According to the present invention, by acid-modifying and oxidizing the activated carbon, its hydrophilicity can be enhanced and its exchange capacity for heavy metal ions in the soil can be improved. In order to obtain modified activated carbon with better performance, preferably, the mass ratio of the activated carbon, the nitric acid aqueous solution and the potassium permanganate aqueous solution is 1:1-4:3-8, preferably 1:2-3:4-6, for example, it can be 1:2:4, 1:2:6, 1:3:4 and 1:3:5 and the range of any values ​​therebetween.

[0027] Preferably, the concentration of the nitric acid aqueous solution is 50-70wt%, preferably 55-65wt%, for example, it can be 55wt%, 60wt%, 63wt% and 65wt% and any value in between.

[0028] Preferably, the concentration of the potassium permanganate aqueous solution is 0.2-0.8 mol / L, preferably 0.4-0.6 mol / L, for example, it can be 0.4 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L and any value in between.

[0029] According to the present invention, the activated carbon can be selected in a wide range, and the performance of different types of activated carbon after modification is also different. In order to obtain modified activated carbon with better performance, preferably, the activated carbon is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, wood activated carbon, coal-based activated carbon, resin-based activated carbon and rubber activated carbon, and more preferably one or more of coconut shell activated carbon, fruit shell activated carbon and wood activated carbon.

[0030] According to the present invention, in order to achieve a better modification effect of activated carbon, the reaction conditions can be adjusted. Preferably, the contact reaction conditions include: temperature 80-120°C, time 2-6h; preferably temperature 90-100°C (for example, it can be 90°C, 92°C, 95°C and 100°C and the range between any values ​​thereof), time 3-4h (for example, it can be 3h, 3.5h, 3.8h and 4h and the range between any values ​​thereof).

[0031] According to the present invention, preferably, the preparation method of the modified activated carbon further comprises, after the contact reaction is completed, centrifuging the reaction solution to remove the liquid phase, washing the solid phase with water and centrifuging it multiple times, and performing a first drying treatment to obtain the modified activated carbon. Preferably, the conditions of the first drying treatment include: temperature 60-120°C, time 6-20h; preferably temperature 80-100°C (for example, it can be 80°C, 85°C, 90°C and 100°C and the range between any values ​​thereof), time 8-16h (for example, it can be 8h, 10h, 12h and 16h and the range between any values ​​thereof).

[0032] According to the present invention, preferably, the method for preparing the modified clay-based material comprises: mixing a clay-based material, an acid solution and a metal oxide, performing an acid leaching reaction, ultrasonic treatment and heat treatment to obtain the modified clay-based material.

[0033] According to the present invention, the introduction of metal oxides into the clay-based material and acid and heat modification can not only dissolve the carbonate impurities contained therein and other cations present in the pores of the crystal structure, but also remove the impurities distributed in the pores, thereby unblocking the pores and increasing the pore volume. In addition, the modified clay-based material will also lose surface water and bound water in the structural skeleton, thereby reducing the adsorption capacity of the water film for heavy metal pollutants and enhancing the adsorption performance of the clay-based material. In order to further enhance the acid and heat modification effect of the clay-based material, preferably, the mass ratio of the clay-based material, the acid solution and the metal oxide is 1:2-5:0.01-0.2, preferably 1:3-4:0.05-0.1, for example, it can be 1:3:0.05, 1:4:0.08, 1:3:0.1 and 1:4:0.05 and the range between any values ​​thereof.

[0034] Preferably, the clay-based material is selected from one or more of halloysite, bentonite, vermiculite, attapulgite, diatomaceous earth and montmorillonite, preferably one or more of halloysite, bentonite, vermiculite and attapulgite, more preferably bentonite and / or attapulgite.

[0035] Preferably, the acid solution is selected from one or more aqueous solutions of nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, preferably an aqueous nitric acid solution and / or an aqueous hydrochloric acid solution.

[0036] Preferably, the concentration of the acid solution is 2-5 mol / L, preferably 3-4 mol / L, for example, it can be 3 mol / L, 3.2 mol / L, 3.6 mol / L, 4 mol / L and any value in between.

[0037] According to the present invention, metal oxides are introduced into clay-based materials for co-modification, and the obtained modified clay-based materials can remove some heavy metal ions (such as Pb 2+ 、Cd 2+ The metal oxide is preferably selected from one or more of magnesium oxide, zinc oxide, aluminum oxide and iron oxide, preferably magnesium oxide and / or zinc oxide.

[0038] Preferably, the conditions of the acid leaching reaction include: temperature 70-100°C, time 2-6h; preferably temperature 80-90°C (for example, it can be 80°C, 85°C, 87°C and 90°C and the range between any values ​​thereof), time 3-5h (for example, it can be 3h, 3.5h, 4h and 5h and the range between any values ​​thereof).

[0039] Preferably, the conditions for the ultrasonic treatment include: a frequency of 60-100 kHz and a time of 0.5-3 h; preferably a frequency of 70-90 kHz (for example, it can be a range between values ​​such as 70 kHz, 80 kHz, 85 kHz and 90 kHz and any values ​​thereof), and a time of 1-2 h (for example, it can be a range between values ​​such as 1 h, 1.2 h, 1.5 h and 2 h and any values ​​thereof).

[0040] According to the present invention, preferably, the preparation method of the modified clay-based material further comprises filtering, washing and performing a second drying treatment on the reaction solution after the ultrasonic treatment is completed. The washing solvent may be, for example, water, and the washing requires washing the solid phase to a neutral pH. The conditions of the second drying treatment include: a temperature of 60-120°C and a time of 6-20h; preferably a temperature of 80-100°C (for example, a range of values ​​such as 80°C, 85°C, 90°C and 100°C and any values ​​thereof), and a time of 8-16h (for example, a range of values ​​such as 8h, 10h, 12h and 16h and any values ​​thereof).

[0041] Preferably, the heat treatment conditions include: a heating rate of 2-5°C / min, a temperature of 300-600°C, and a time of 1-5h; preferably a heating rate of 3-4°C / min (for example, it can be 3°C / min, 3.2°C / min, 3.5°C / min and 4°C / min and the range between any values ​​thereof), a temperature of 400-500°C (for example, it can be 400°C, 450°C, 480°C and 500°C and the range between any values ​​thereof), and a time of 2-4h (for example, it can be 2h, 2.5h, 3h and 4h and the range between any values ​​thereof).

[0042] Preferably, the heat treatment is performed in an inactive gas atmosphere, and the inactive gas may be, for example, nitrogen and / or argon.

[0043] According to the present invention, in step (3), compound fertilizer is applied to the soil to improve the nutritional status of the soil, thereby providing nutrients for the growth of long-leaf bell grass. Long-leaf bell grass has low requirements for soil and has good adaptability in high-altitude mountains with relatively poor soil. At the same time, its planting cost and maintenance cost are also low, so it is sufficient to select a specific compound fertilizer to meet its required fertility. In order to reduce costs and realize waste utilization, preferably, the compound fertilizer includes nitrogen, phosphorus and potassium compound fertilizers, fresh animal manure and river silt.

[0044] According to the present invention, the fresh animal manure may include, for example, cow manure, pig manure, horse manure, chicken manure and other animal manure, which contains rich organic matter and various nutrients required by crops, mainly including cellulose, hemicellulose, lignin, protein and its decomposition components, fat, organic acid, enzyme and various inorganic salts. The river sludge is the river sludge after drainage and air drying, which is rich in organic fertilizer and microorganisms.

[0045] According to the present invention, in order to make the soil have a better nutritional state, promote the growth of long-leaf bell grass, and avoid the phenomenon of seedling burning caused by excessive fertility, the amount of compound fertilizer and the mass ratio of the components contained therein can be adjusted. Preferably, the mass ratio of the nitrogen, phosphorus and potassium compound fertilizer, the fresh animal manure and the river silt is 1:200-400:600-900, preferably 1:250-350:700-800, for example, it can be 1:300:750, 1:250:800, 1:350:700 and 1:300:800 and the range between any values ​​thereof.

[0046] Preferably, the amount of the compound fertilizer is 150-350 kg / m 2 , preferably 200-300kg / m 2 , for example, 200 kg / m 2 , 250kg / m 2 , 280kg / m 2 and 300kg / m 2 The range between the values ​​and any values ​​in between.

[0047] According to the present invention, in step (4), in order to make the long-leaf bell grass grow better and achieve a better repair effect on the soil, preferably, the planting method of the long-leaf bell grass includes: digging pits on the soil surface, placing the long-leaf bell grass seedlings obliquely in the pits, burying the roots of the seedlings in the soil, covering with a layer of loose soil after compacting and compacting again, and watering to make the soil and the root system dense.

[0048] Preferably, the depth of the pit is 20-40 cm, the width of the square opening of the pit is 20-40 cm, and the row spacing between each pit is 3m*3m.

[0049] According to the present invention, in step (4), the addition of the composite bacterial agent enables the specific bacterial species therein to cooperate with the soil conditioner and the long-leafed bell grass, further promoting the degradation and reduction of heavy metals in the soil, converting the heavy metals in the ionic state into the elemental state, and realizing the effective deposition of heavy metals. At the same time, the composite bacterial agent can also degrade the organic pollutants present in the soil, converting them into other non-toxic or less toxic substances such as carbon dioxide and water. In addition, the application of the composite bacterial agent can also consolidate the soil fertility and have a broad-spectrum control effect on most pathogens in the soil, and can also promote the growth of long-leafed bell grass. In order to obtain better results, preferably, the mass ratio of the Pseudomonas aeruginosa, the Bacillus clausii, the black ball paint spot and the round brown nitrogen-fixing bacteria is 1:2-5:0.5-3:2-5, preferably 1:3-4:1-2:3-4, for example, it can be 1:3:1:3, 1:4:2:3, 1:3:2:4 and 1:4:1:4 and the range of any values ​​thereof.

[0050] Preferably, the dosage of the composite bacterial agent is 20-30 g / m 2 , for example, it can be 20g / m 2 , 25g / m 2 , 28g / m 2 and 30g / m 2 The range between the values ​​and any values ​​in between.

[0051] According to the present invention, preferably, in steps (1) to (4), watering is performed after each tillage. Preferably, in steps (1) to (4), the tillage depth is 20-40 cm.

[0052] According to the present invention, in order to facilitate the growth of long-leaf bell grass, preferably, the method further comprises, after step (4), completely tilling the soil and removing weeds within 20-40 days, and applying top dressing within 3-6 months.

[0053] According to the present invention, the high-altitude abandoned mines described in the present invention generally refer to abandoned mines in areas with an altitude of more than 800m.

[0054] The present invention provides a suitable acid-base environment for subsequent steps by adjusting the pH of the soil of high-altitude abandoned mines, applying soil conditioners to adsorb and deposit heavy metals and harmful substances in the soil, and applying compound fertilizers to improve the nutritional state of the soil, so that the soil reaches a state sufficient for planting and growing long-leaf bell grass, and then by planting long-leaf bell grass adapted to the high-altitude climate, and using its special biological characteristics to cooperate with soil conditioners and compound bacterial agents, etc., so as to further absorb, enrich, fix and degrade heavy metals and pollutants, and with the cooperation of various elements, water and soil and fertility are consolidated, the growth of long-leaf bell grass is promoted, and finally the soil is repaired. In addition, the planting and maintenance costs of long-leaf bell grass are low, the ecological benefits are obvious, and the growth is rapid. It can increase the vegetation coverage of abandoned mines in a short time, achieve the effect of ecological restoration, and also have certain economic benefits.

[0055] The present invention will be described in detail below through examples.

[0056] In the following examples: coconut shell activated carbon and fruit shell activated carbon were purchased from Henan Zhongju Purification Co., Ltd.; bentonite was purchased from Zhejiang Huate New Materials Co., Ltd.; attapulgite was purchased from Anhui Tianke Mineral Co., Ltd.; nitrogen, phosphorus and potassium compound fertilizer was purchased from Shandong Linong Fertilizer Co., Ltd.; other conventional materials can be purchased.

[0057] Example 1

[0058] This example is aimed at repairing an abandoned mine at an altitude of about 1,300 meters. The repair process is as follows:

[0059] (1) The abandoned mine site was leveled, the cultivated soil layer with a depth of 30 cm was excavated, large branches, gravel and other debris in the soil were removed, and large soil clumps were broken up and then backfilled to the original location, and a drainage system was built. At the same time, the pH value and heavy metal content of the water under the soil were measured.

[0060] (2) Apply an appropriate amount of lime evenly on the soil surface, till the soil layer to a depth of 30 cm evenly, water it, and let it stand for 2 hours. The average pH value of the soil surface was measured to be 6.2.

[0061] (3) Apply soil conditioner evenly on the surface of the soil treated in step (2), with an amount of 1.6 kg / m 2 , evenly plow the soil layer to a depth of 30 cm on the surface, water it, and then water it once a day for 20 days.

[0062] Among them, the above-mentioned soil conditioner includes modified activated carbon and modified clay-based materials in a mass ratio of 1:8.

[0063] The preparation process of modified activated carbon is as follows: coconut shell activated carbon, 65wt% nitric acid aqueous solution and 0.5mol / L potassium permanganate aqueous solution in a mass ratio of 1:2:5 are mixed evenly, reacted at 90°C for 3h, and after the reaction is completed, the reaction liquid is centrifuged to remove the liquid phase, the solid phase is washed with water and centrifuged three times, and dried at 100°C for 12h to obtain modified activated carbon.

[0064] The preparation process of the modified clay-based material is as follows: bentonite, 3 mol / L nitric acid aqueous solution and magnesium oxide in a mass ratio of 1:3:0.08 are mixed evenly, reacted at 90°C for 3 hours, and then ultrasonically treated at a frequency of 70 kHz for 2 hours. The reaction solution is filtered, washed with water to a neutral pH, dried at 80°C for 12 hours, and then transferred to a tubular furnace, heated to 500°C at a heating rate of 3°C / min under an argon atmosphere, and reacted at 500°C for 3 hours. After cooling, the modified clay-based material is obtained.

[0065] (4) Apply compound fertilizer evenly on the surface of the soil treated in step (3), with an amount of 260 kg / m 2 , evenly plow the soil layer at a depth of 30cm on the surface, and water it. Compound fertilizers include nitrogen, phosphorus and potassium compound fertilizers with a mass ratio of 1:300:750, fresh animal manure (a mixture of pig manure and chicken manure with a mass ratio of 2:1) and river silt that has been drained and air-dried.

[0066] (5) Dig pits on the soil surface treated in step (4), the depth of the pits is 30 cm, the width of the square opening of the pits is 30 cm, and the row spacing between each pit is 3m*3m. Place the long-leaved bell grass seedlings obliquely in the pits, bury the roots of the seedlings in the soil, cover with a layer of loose soil after compacting, and compact again, and water to make the soil and roots dense. Then evenly apply the composite bacterial agent to the pits, with an amount of 20g / m 2 The composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, Mycosporium nigromatum and Azotobacter rotundifolia in a mass ratio of 1:3:2:4.

[0067] (6) 30 days after step (5), the site is fully cultivated, soil is loosened and weeds are removed. 4 months after step (5), top dressing is performed.

[0068] (7) Three months after step (6), the pH value of the soil at the testing site and the heavy metal content of the soil leaching liquid were tracked, and the survival rate of the long-leaved bell grass was investigated. The test results are shown in Table 1. The detection methods in steps (1) and (7) are based on the methods described in HJ962-2018, HJ557-2010 and GB7475-87.

[0069] Table 1

[0070]

[0071] Example 2

[0072] The site of this embodiment and that of embodiment 1 belong to different areas of the same abandoned mine and have the same area. The restoration process is as follows:

[0073] (1) The abandoned mine site was leveled, the cultivated soil layer with a depth of 40 cm was excavated, large branches, gravel and other debris in the soil were removed, and large soil clumps were broken up and then backfilled to the original location, and a drainage system was built. At the same time, the pH value and heavy metal content of the water under the soil were measured.

[0074] (2) Apply an appropriate amount of caustic soda evenly on the soil surface, till the soil layer to a depth of 40 cm evenly, water it, and let it stand for 2 hours. The average pH value of the soil surface was measured to be 5.7.

[0075] (3) Apply soil conditioner evenly on the surface of the soil treated in step (2), with an amount of 2.3 kg / m 2 , evenly plow the soil layer to a depth of 30 cm on the surface, water it, and then water it once a day for 10 days.

[0076] Among them, the above-mentioned soil conditioner includes modified activated carbon and modified clay-based materials in a mass ratio of 1:6.

[0077] The preparation process of modified activated carbon is as follows: fruit shell activated carbon, 55wt% nitric acid aqueous solution and 0.6mol / L potassium permanganate aqueous solution in a mass ratio of 1:3:4 are mixed evenly, reacted at 100°C for 4 hours, and after the reaction is completed, the reaction liquid is centrifuged to remove the liquid phase, the solid phase is washed with water and centrifuged three times, and dried at 80°C for 16 hours to obtain modified activated carbon.

[0078] The preparation process of the modified clay-based material is as follows: attapulgite, 4 mol / L hydrochloric acid aqueous solution and zinc oxide in a mass ratio of 1:4:0.05 are mixed evenly, reacted at 80°C for 5 hours, and then ultrasonically treated at a frequency of 90 kHz for 1 hour. The reaction solution is filtered, washed with water to a neutral pH, dried at 100°C for 10 hours, and then transferred to a tubular furnace, heated to 400°C at a heating rate of 4°C / min under an argon atmosphere, and reacted at 400°C for 2 hours. After cooling, the modified clay-based material is obtained.

[0079] (4) Apply compound fertilizer evenly on the surface of the soil treated in step (3), with an amount of 220 kg / m 2 , evenly plow the soil layer of 40cm deep on the surface and water it. The compound fertilizer includes nitrogen, phosphorus and potassium compound fertilizer with a mass ratio of 1:250:700, fresh pig manure and river silt that has been drained and air-dried.

[0080] (5) Dig pits on the soil surface treated in step (4), the depth of the pits is 20 cm, the width of the square opening of the pits is 30 cm, and the row spacing between each pit is 3m*3m. Place the long-leaved bell grass seedlings obliquely in the pits, bury the roots of the seedlings in the soil, cover with a layer of loose soil after compacting, and compact again, and water to make the soil and roots dense. Then evenly apply the composite bacterial agent to the pits, with an amount of 30g / m 2 The composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, Mycosporium nigromatum and Azotobacter rotundifolia in a mass ratio of 1:4:2:3.

[0081] (6) 20 days after step (5), the site is fully cultivated, soil is loosened and weeds are removed. 6 months after step (5), top dressing is performed.

[0082] (7) Three months after step (6), the pH value of the soil at the testing site and the heavy metal content of the soil leaching liquid were tracked, and the survival rate of the long-leaved bell grass was investigated. The test results are shown in Table 2. The detection methods in steps (1) and (7) are based on the methods described in HJ962-2018, HJ557-2010 and GB7475-87.

[0083] Table 2

[0084]

[0085] Example 3

[0086] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0087] The method of Example 1 is different from that in step (3), the amount of soil conditioner used is 0.8 kg / m 2 ,The final test results are shown in Table 3.

[0088] Table 3

[0089]

[0090] Example 4

[0091] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0092] The method of Example 1 is different from that in step (5), the amount of the composite bacterial agent is 10 g / m 2 ,The final test results are shown in Table 4.

[0093] Table 4

[0094]

[0095] Example 5

[0096] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0097] The method of Example 1 is different in that in step (3), the soil conditioner includes modified activated carbon and modified clay-based material in a mass ratio of 1:4. The final test results are shown in Table 5.

[0098] Table 5

[0099]

[0100] Example 6

[0101] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0102] The method of Example 1 is different in that in step (3), the soil conditioner includes modified activated carbon and modified clay-based material in a mass ratio of 1:10. The final test results are shown in Table 6.

[0103] Table 6

[0104]

[0105] Example 7

[0106] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0107] The method of Example 1 is different in that in step (5), the composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, Mycosporium nigromaculata and Azotobacter rotundifolia in a mass ratio of 1:5:0.5:3. The final test results are shown in Table 7.

[0108] Table 7

[0109]

[0110] Example 8

[0111] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0112] The method of Example 1 is different in that in step (5), the composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, Mycosporium nigromaculata and Azotobacter rotundifolia in a mass ratio of 1:2:3:5. The final test results are shown in Table 8.

[0113] Table 8

[0114]

[0115] Comparative Example 1

[0116] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0117] The method of Example 1 was used, except that step (3) was not performed. The final test results are shown in Table 9.

[0118] Table 9

[0119]

[0120] Comparative Example 2

[0121] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0122] The method of Example 1 was used, except that in step (5), no composite bacterial agent was applied. The final test results are shown in Table 10.

[0123] Table 10

[0124]

[0125] Comparative Example 3

[0126] The site of this embodiment and that of Embodiment 1 belong to different areas of the same abandoned mine and have the same area.

[0127] The method of Example 1 is different in that in step (3), the soil conditioner is coconut shell activated carbon and bentonite in a mass ratio of 1:8. The final test results are shown in Table 11.

[0128] Table 11

[0129]

[0130] From the data in Tables 1 to 8, it can be seen that Examples 1-8 using the technical solution of the present invention achieve good restoration effects on the soil of abandoned mines at high altitudes, the soil pH remains stable, the heavy metal content is greatly reduced, and the plant survival rate is as high as 90% or more, among which Examples 1 and 2 have the best restoration effects, with a plant survival rate of 100%, achieving a good ecological restoration effect. However, Comparative Examples 1-3, which do not adopt the technical solution of the present invention, have a low survival rate of long-leafed bell grass and a high content of heavy metals in the soil, indicating that the soil restoration effect is poor.

[0131] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for soil remediation of abandoned mines at high altitudes using long-leaved bell grass, characterized in that: The method includes: (1) Apply pH regulator to the soil and till the soil to adjust the soil pH to 5.7-6.5; (2) applying a soil conditioner to the soil after plowing in step (1), plowing the soil, and watering the soil once a day for 10 to 30 days; (3) applying compound fertilizer to the soil after plowing in step (2), and plowing; (4) planting long-leafed bellflower on the soil after plowing in step (3) and applying a composite bacterial agent; The soil conditioner comprises modified activated carbon and modified clay-based materials, and the amount of the soil conditioner is 0.8-3.2 kg / m 2 The composite bacterial agent includes Pseudomonas aeruginosa, Bacillus clausii, black ball paint spot and round brown nitrogen-fixing bacteria, and the dosage of the composite bacterial agent is 10-40g / m 2 .

2. The method according to claim 1, wherein: The mass ratio of the modified activated carbon to the modified clay-based material is 1:4-10, preferably 1:6-8; And / or, the amount of the soil conditioner is 1.6-2.4 kg / m 2 .

3. The method according to claim 1 or 2, wherein: The mass ratio of the Pseudomonas aeruginosa, the Bacillus clausii, the Myrocera nigromaculata and the Azotobacter rotundifolia is 1:2-5:0.5-3:2-5, preferably 1:3-4:1-2:3-4; And / or, the dosage of the composite bacterial agent is 20-30g / m 2 .

4. The method according to any one of claims 1 to 3, wherein: The preparation method of the modified activated carbon comprises: contacting activated carbon, nitric acid aqueous solution and potassium permanganate aqueous solution to obtain the modified activated carbon; Preferably, the mass ratio of the activated carbon, the nitric acid aqueous solution and the potassium permanganate aqueous solution is 1:1-4:3-8, preferably 1:2-3:4-6; Preferably, the concentration of the aqueous nitric acid solution is 50-70wt%, preferably 55-65wt%; Preferably, the concentration of the potassium permanganate aqueous solution is 0.2-0.8 mol / L, preferably 0.4-0.6 mol / L; Preferably, the activated carbon is selected from one or more of coconut shell activated carbon, fruit shell activated carbon, wood activated carbon, coal activated carbon, resin-based activated carbon and rubber activated carbon, more preferably one or more of coconut shell activated carbon, fruit shell activated carbon and wood activated carbon; Preferably, the contact reaction conditions include: temperature 80-120°C, time 2-6h; preferably temperature 90-100°C, time 3-4h.

5. The method according to any one of claims 1 to 4, wherein: The preparation method of the modified clay-based material comprises: mixing the clay-based material, an acid solution and a metal oxide, performing an acid leaching reaction, ultrasonic treatment and heat treatment to obtain the modified clay-based material; Preferably, the mass ratio of the clay-based material, the acid solution and the metal oxide is 1:2-5:0.01-0.2, preferably 1:3-4:0.05-0.1; Preferably, the clay-based material is selected from one or more of halloysite, bentonite, vermiculite, attapulgite, diatomaceous earth and montmorillonite, preferably one or more of halloysite, bentonite, vermiculite and attapulgite, more preferably bentonite and / or attapulgite; Preferably, the acid solution is selected from one or more aqueous solutions of nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, preferably an aqueous nitric acid solution and / or an aqueous hydrochloric acid solution; Preferably, the concentration of the acid solution is 2-5 mol / L, preferably 3-4 mol / L; Preferably, the metal oxide is selected from one or more of magnesium oxide, zinc oxide, aluminum oxide and iron oxide, preferably magnesium oxide and / or zinc oxide; Preferably, the conditions of the acid leaching reaction include: temperature 70-100°C, time 2-6h; preferably temperature 80-90°C, time 3-5h; Preferably, the ultrasonic treatment conditions include: frequency 60-100kHz, time 0.5-3h; preferably frequency 70-90kHz, time 1-2h; Preferably, the heat treatment conditions include: heating rate 2-5°C / min, temperature 300-600°C, time 1-5h; preferably heating rate 3-4°C / min, temperature 400-500°C, time 2-4h.

6. The method according to any one of claims 1 to 5, wherein: The pH regulator is selected from one or more of lime, caustic soda, plant ash, limestone and phosphogypsum, preferably lime and / or caustic soda; And / or, the compound fertilizer comprises nitrogen-phosphorus-potassium compound fertilizer, fresh animal manure and river sludge; preferably, the mass ratio of the nitrogen-phosphorus-potassium compound fertilizer, the fresh animal manure and the river sludge is 1:200-400:600-900, preferably 1:250-350:700-800; And / or, the dosage of the compound fertilizer is 150-350kg / m 2 , preferably 200-300kg / m 2 .

7. The method according to any one of claims 1 to 6, wherein: In step (4), the method for planting the long-leafed bell grass comprises: digging a pit on the soil surface, placing the long-leafed bell grass seedlings obliquely in the pit, burying the roots of the seedlings in the soil, tamping it down, covering it with a layer of loose soil and tamping it down again, and watering to make the soil and the root system dense; Preferably, the depth of the pit is 20-40 cm, the width of the square opening of the pit is 20-40 cm, and the row spacing between each pit is 3m*3m.

8. The method according to any one of claims 1 to 7, wherein: In steps (1) to (4), watering is performed after each tillage; And / or, in steps (1) to (4), the tillage depth is 20-40 cm.

9. The method according to any one of claims 1 to 8, wherein: The method further comprises leveling the abandoned mine site and constructing a drainage system before performing step (1).

10. The method according to any one of claims 1 to 9, wherein: The method further comprises, after performing step (4), performing complete soil loosening and weed removal within 20-40 days, and performing topdressing within 3-6 months.

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