Method for soil reclamation by using bulk innocent treatment of coal gangue

Abstract

The invention discloses a method for soil reclamation through bulk harmless treatment of coal gangue. The method comprises the following steps: firstly, crushing coal gangue, grading and utilizing, separating out different components, and treating clay minerals; the method comprises the following steps: collecting a sample from specific-depth soil of a coal gangue storage yard, extracting a pollutant-tolerant functional strain, and rapidly propagating to prepare a compound bacteria solution; clay minerals and the compound bacteria liquid are mixed and subjected to harmless and nutrient activation treatment; finally, the harmless and nutrient-activated clay mineral is mixed with soil to be reclaimed, and the reclamation matrix is prepared and used for soil reclamation. According to the method, resources can be efficiently utilized, energy consumption and pollution are reduced, economic benefits are high, and industrialization of bulk utilization of the coal gangue is promoted.

Description

Technical Field

[0001] The present invention relates to the field of advanced environmental protection industry, and in particular to a method for harmlessly treating large quantities of coal gangue for soil reclamation. Background Art

[0003] Multiple national departments have jointly issued a number of policies to promote the comprehensive utilization of industrial solid waste. For example, the "Implementation Plan on Accelerating the Comprehensive Utilization of Industrial Resources" issued by multiple departments in 2022 clearly states that by 2025, the level of comprehensive utilization of bulk industrial solid waste should be improved, and the comprehensive utilization rate should be 57%. Major coal-producing provinces have also responded positively. Shanxi Province has issued relevant action plans to explore new ways to utilize coal gangue; Guizhou Province plans to achieve a comprehensive utilization rate of 70% for bulk industrial solid waste by 2025, and solicits opinions on the technical regulations for filling ditches with coal gangue to create land. These policies point the way for the comprehensive utilization of coal gangue and also put forward higher requirements for technological innovation.

[0004] Gangue is a solid waste generated during coal mining and washing. For a long time, the series of problems it brings have seriously restricted the development of the coal industry. Large amounts of gangue are piled up in the open air, which not only occupies precious land resources, but also causes environmental pollution and secondary geological disasters. After being eroded by rainwater, gangue produces acidic water, which accelerates the dissolution of toxic heavy metal ions and pollutes the surrounding soil and water bodies; some gangue has a high sulfur content, is prone to spontaneous combustion, releases harmful gases, and affects air quality. At present, these problems have restricted the release of coal production capacity, and efficient treatment of gangue has become a practical problem that coal mining companies need to solve urgently. Grading and quality-based utilization is the core technical means to achieve the harmless use of large quantities of gangue for soil. Through cascade crushing and sorting processes, the gangue ore can be separated into different components such as coal, soil, and stone to achieve refined utilization of resources. The separated "coal" component can be used as power coal. The separated "soil" component can be used as a soil improvement material after rapid microbial proliferation and harmlessness, and can be used for soil reconstruction, saline-alkali land improvement, etc.; the "stone" component can be made into construction sand and gravel aggregate to increase economic benefits.

[0005] From the perspective of the utilization of coal gangue encouraged by the state, underground filling, power generation, production of building materials, recycling of mineral products, land reclamation and ecological restoration are all important ways, but considering the resource utilization efficiency, environmental benefits and economic benefits, large-scale harmless use of it in soil has significant advantages. The composition of coal gangue is similar to that of soil, and contains trace elements required for plant growth. It can be used for soil remediation and reclamation through harmless treatment, which conforms to the concept of "from the soil, to the soil", and can realize the recycling of resources. Moreover, compared with other utilization methods, it can be used for soil reclamation to absorb a large amount of coal gangue, effectively solve the problem of coal gangue accumulation, promote ecological environment restoration, and meet the needs of the national ecological strategy.

[0006] Therefore, the present invention develops a method for harmlessly treating large quantities of coal gangue for soil reclamation, which has high resource utilization efficiency, low energy consumption, high economic benefits, and reduces environmental pollution, and is expected to promote the industrialization process of large-scale utilization of coal gangue. Summary of the invention

[0007] The invention aims to provide a method for harmlessly treating large quantities of coal gangue for soil reclamation, so as to solve the problems of land occupation and environmental pollution caused by the long-term accumulation of large amounts of coal gangue, realize the resource utilization of coal gangue, promote soil reclamation and ecological environment restoration, and at the same time take into account resource utilization efficiency, environmental benefits and economic benefits, and promote the industrialization process of large-scale utilization of coal gangue.

[0008] To achieve the above object of the invention, the specific technical solution of the present invention is:

[0009] S01. The gangue is crushed, the rock blocks are initially screened out, the coal, pyrite and clay minerals are separated by air separation according to the density difference, and the clay minerals are screened and dried;

[0010] S02. Collect samples from contaminated soil at a certain depth in a coal gangue dump, extract and separate the native microorganisms in the samples to obtain functional strains that tolerate pollutants;

[0011] S03. The screened strain obtained in step S02 is expanded in a rapid expansion liquid medium using an optimized expansion process to obtain a composite bacterial solution;

[0012] S04. The clay mineral obtained in step S01 is mixed with the composite bacterial solution in step S03 to remove heavy metals and organic pollutants and harmlessly treat the clay mineral;

[0013] S05. The harmless clay mineral obtained in step S04 is mixed with a nutrient matrix, and an engineering bacterial solution is added to activate the clay mineral;

[0014] S06. Mix the clay minerals activated with harmless nutrients in step S05 with the soil to be reclaimed, adjust the moisture content to form a reclamation matrix, and lay a reclamation matrix layer of a certain thickness in the area to be repaired for soil reclamation.

[0015] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the wind speed in the air selection process of step S01 is controlled between 5m / s and 30m / s, the wind pressure is controlled between 1000 and 5000Pa, and the clay minerals are crushed and sieved with 10 to 200 meshes.

[0016] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the soil depth of the sample collected in step S02 is 0.5 to 3 m, and the method for extracting native microorganisms is one or two of gradient plate preparation, dilution coating method, single cell separation technology, and enrichment culture, or a mixture of two or more thereof.

[0017] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the pollutants in step S02 may be one or two of mercury, cadmium, lead, arsenic, chromium, copper, polycyclic aromatic hydrocarbons, phenols, aromatic hydrocarbons, aliphatic hydrocarbons, and sulfur-containing organic matter, or a mixture of two or more thereof.

[0018] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, in which the rapid propagation liquid culture medium in step S03 is added with a carbon source so that its content reaches 5-30 g / L, the total amount of nitrogen source reaches 2-15 g / L, the total amount of growth factor reaches 0.01-0.05 g / L, the total amount of inorganic salt reaches 1-15 g / L, the amount of iron element added is 10-200 mg / L, the amount of zinc element added is 10-60 mg / L, the amount of manganese element added is 5-50 mg / L, the propagation temperature is controlled between 30-37°C, the pH value range is 6-9, and the propagation time is 0.1-3 h.

[0019] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the clay mineral:composite bacterial solution in step S04 is mixed in a mass ratio of 1:(1-10), the harmless treatment temperature is 25-37° C., and the reaction time is 0.5h-24h.

[0020] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the nutrient matrix of step S05 is one or two of sheep manure, chicken manure, pig manure, straw powder, forage powder, wheat bran, urea, compound fertilizer, phosphate fertilizer, potash fertilizer, bentonite, zeolite powder, sodium polyacrylate, xanthan gum, guar gum, sodium silicate, and sodium bicarbonate, or a mixture of two or more thereof.

[0021] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, wherein the harmless clay mineral in step S05 is mixed with the nutrient matrix in a mass ratio of 1:(0.1-10), the temperature of the nutrient activated clay mineral is 20-105°C, the reaction time is 0.5-200h, and the water content is controlled at 15%-70%.

[0022] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, and the engineering bacterial liquid for nutrient activation of clay minerals in step S05 can be one or two of the following, or a mixture of two or more, selected from the group consisting of thermophilic Streptomyces violaceus, Bacillus cereus, thermophilic amylolytic Streptomyces, Bacillus subtilis, Trichoderma harzianum, Rhizobium, Pseudomonas, Penicillium oxalicum, Acinetobacter luffii, and Bacillus mucilaginosus.

[0023] The method for harmlessly treating large quantities of coal gangue for soil reclamation as described above is preferred, in which the harmlessly nutritious clay minerals in step S05 are mixed with the soil to be reclaimed in a mass ratio of 1:(1-10), and the water content is adjusted to 10-35% to form a reclamation matrix, and a 10-60 cm reclamation matrix layer is laid in the area to be repaired for soil reclamation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Technology Roadmap DETAILED DESCRIPTION

[0025] Example 1

[0026] 10 tons of coal gangue from a coal mine in Inner Mongolia were selected, and its chemical composition and content are shown in Table 1. The rock was crushed by a crusher and separated by primary screening. Coal, pyrite and clay minerals were separated according to density differences using air separation equipment with a wind speed of 20m / s and a wind pressure of 3000Pa. The clay minerals were sieved through a 150-mesh sieve and then dried in an oven at 80°C to constant weight. 5kg of soil samples were collected at a depth of 1.5m in the coal gangue yard. The original microorganisms in the samples were extracted and separated by combining the gradient plate preparation method and the enrichment culture method. Functional strains with tolerance to mercury, cadmium and polycyclic aromatic hydrocarbons were successfully screened, including Pseudomonas and Penicillium oxalicum. Prepare a rapid propagation liquid medium, add glucose as a carbon source to make it reach 15g / L; use ammonium sulfate and yeast extract as nitrogen sources to make the total nitrogen source reach 8g / L; use vitamin B group as growth factors, with a total amount of 0.03g / L; add potassium dihydrogen phosphate, magnesium sulfate, etc. as inorganic salts, with a total amount of 8g / L; add iron in the form of ferrous sulfate, with an addition amount of 100mg / L; add zinc sulfate as zinc sulfate, with an addition amount of 30mg / L; add manganese sulfate as manganese sulfate, with an addition amount of 25mg / L. The selected functional strains were inoculated into the culture medium, and cultured under shaking conditions of 35℃ and pH 7.5 for 2h to obtain a composite bacterial liquid. 500kg of dried clay minerals were mixed with 500kg of composite bacterial solution and reacted in an environment of 30℃ for 12h to achieve the removal of heavy metals and organic pollutants in clay minerals. The harmless treatment was completed in accordance with the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB18599-2020), "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018) and "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB 5085.3-2007) standards. Sheep manure, straw powder, compound fertilizer and bentonite were selected as nutrient matrices and mixed in a mass ratio of 1:3 between harmless clay minerals and nutrient matrices. The engineered bacterial solution composed of thermophilic Streptomyces violaceus and Bacillus subtilis was added, and the nutrient activation treatment was carried out for 40h at 50℃ and a water content of 40%. In the soil area to be reclaimed in a coal mine in Inner Mongolia, the clay minerals after nutrient activation were mixed with the soil to be reclaimed at a mass ratio of 1:5, and the water content was adjusted to 25% to make a reclamation matrix. A 30cm thick reclamation matrix layer was laid in the area for soil reclamation.

[0027] Table 1 Daqingshan Coal Mine in Inner Mongolia

[0028]

[0029] Example 2

[0030] 8 tons of gangue from a coal mine in Guizhou were taken, and its chemical composition and content are shown in Table 2. After crushing, the rock blocks were initially screened out. During the air separation, the wind speed was set to 15m / s and the wind pressure was set to 2000Pa to separate the different components. The clay minerals were passed through a 100-mesh sieve and dried at 70°C. 3kg of soil samples were collected at a depth of 2m in the gangue yard. Using the dilution coating method and single-cell separation technology, functional strains that tolerate lead, arsenic and phenol pollutants were isolated, including Bacillus cereus and Acinetobacter luffii. In the rapid propagation liquid culture medium, sucrose was used as the carbon source to make its content 20g / L; urea and peptone were used as nitrogen sources, and the total amount of nitrogen source was 10g / L; amino acids were selected as growth factors, with a total amount of 0.04g / L; a variety of inorganic salts were added, with a total amount of 10g / L; iron was added in an amount of 150mg / L, zinc was 40mg / L, and manganese was 30mg / L. The composite bacterial solution was obtained by culturing for 1.5 hours at 32°C and pH 8. 400 kg of clay minerals were mixed with 800 kg of composite bacterial solution at a mass ratio of 1:2, and reacted at 28°C for 18 hours. The harmless treatment was completed according to the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB 18599-2020), "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018) and "Hazardous Waste Identification Standard Leaching Toxicity Identification" (GB 5085.3-2007). Chicken manure, wheat bran, potash fertilizer and zeolite powder were selected as nutrient matrix and mixed at a mass ratio of 1:2 between harmless clay minerals and nutrient matrix. The engineered bacterial solution of thermophilic amylase Streptomyces and rhizobia was added, and the nutrition was activated for 20 hours at 40°C and a water content of 35%. For the acidic soil to be reclaimed around an abandoned coal mine, the clay minerals after nutrient activation were mixed with the soil to be reclaimed at a mass ratio of 1:4, and the water content was adjusted to 20% to make a reclamation matrix. A 20cm thick reclamation matrix layer was laid in the area to carry out soil reclamation work.

[0031] Table 2 Guizhou Tongzi Coal Mine

[0032]

Claims

1. A method for harmlessly treating large quantities of coal gangue for soil reclamation, characterized in that: The method comprises the following steps: S01. The gangue is crushed, the rock blocks are initially screened out, the coal, pyrite and clay minerals are separated by air separation according to the density difference, and the clay minerals are screened and dried; S02. Collect samples from contaminated soil at a certain depth in a coal gangue dump, extract and separate the native microorganisms in the samples to obtain functional strains that tolerate pollutants; S03. The screened strain obtained in step S02 is expanded in a rapid expansion liquid medium using an optimized expansion process to obtain a composite bacterial solution; S04. The clay mineral obtained in step S01 is mixed with the composite bacterial solution in step S03 to remove heavy metals and organic pollutants and harmlessly treat the clay mineral; S05. The harmless clay mineral obtained in step S04 is mixed with a nutrient matrix, and an engineering bacterial solution is added to activate the clay mineral; S06. Mix the clay minerals activated with harmless nutrients in step S05 with the soil to be reclaimed, adjust the moisture content to form a reclamation matrix, and lay a reclamation matrix layer of a certain thickness in the area to be repaired for soil reclamation.

2. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: In the air selection process of step S01, the wind speed is controlled between 5m / s and 30m / s, the wind pressure is controlled between 1000 and 5000Pa, and the clay minerals are crushed and sieved with 10 to 200 meshes.

3. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The soil depth of the sample collected in step S02 is 0.5 to 3 m, and the method for extracting the native microorganisms is one or two of gradient plate preparation, dilution coating method, single cell separation technology, and enrichment culture, or a mixture of two or more thereof.

4. According to the method for harmlessly treating large quantities of coal gangue for soil reclamation as described in claim 1, the pollutants in step S02 can be one or two of mercury, cadmium, lead, arsenic, chromium, copper, polycyclic aromatic hydrocarbons, phenols, aromatic hydrocarbons, aliphatic hydrocarbons, and sulfur-containing organic matter, or a mixture of two or more thereof.

5. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The rapid propagation liquid culture medium of step S03 is added with a carbon source so that its content reaches 5-30 g / L, the total amount of nitrogen source reaches 2-15 g / L, the total amount of growth factor reaches 0.01-0.05 g / L, the total amount of inorganic salt reaches 1-15 g / L, the amount of iron element added is 10-200 mg / L, the amount of zinc element added is 10-60 mg / L, the amount of manganese element added is 5-50 mg / L, the propagation temperature is controlled between 30-37°C, the pH value range is 6-9, and the propagation time is 0.1-3 h.

6. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The clay mineral and the composite bacterial solution in step S04 are mixed in a mass ratio of 1:(1-10), the detoxification temperature is 25-37° C., and the reaction time is 0.5-24 h.

7. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The nutrient matrix of step S05 is one or two or a mixture of two or more of sheep manure, chicken manure, pig manure, straw powder, forage powder, wheat bran, urea, compound fertilizer, phosphate fertilizer, potash fertilizer, bentonite, zeolite powder, sodium polyacrylate, xanthan gum, guar gum, sodium silicate, and sodium bicarbonate.

8. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The harmless clay mineral in step S05 is mixed with the nutrient matrix in a mass ratio of 1:(0.1-10), the temperature of the nutrient activated clay mineral is 20-105° C., the reaction time is 0.5-200 hours, and the water content is controlled at 15%-70%.

9. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The engineering bacterial liquid for nutrient activation of clay minerals in step S05 can be one or two or a mixture of two or more of Streptomyces thermophilus, Bacillus cereus, Streptomyces thermomyces, Bacillus subtilis, Trichoderma harzianum, Rhizobium, Pseudomonas, Penicillium oxalicum, Acinetobacter luffi, and Bacillus mucilaginosus.

10. The method for harmlessly treating large quantities of coal gangue for soil reclamation according to claim 1, characterized in that: The harmless clay mineral in step S05 is mixed with the soil to be reclaimed in a mass ratio of 1:(1-10), and the water content is adjusted to 10-35% to form a reclamation matrix. A 10-60 cm reclamation matrix layer is laid in the area to be repaired for soil reclamation.

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