Method for preparing solid waste-based soil conditioner by utilizing microbial mineralized coal gangue

Abstract

The invention discloses a method for preparing a solid waste-based soil conditioner by using microorganism mineralized coal gangue, which comprises the following steps: mineralizing a coal gangue compost substrate by adopting a microorganism mineralization technology to form a coal gangue solid waste soil conditioner; the method comprises the following steps: performing an aerobic composting fermentation test by using coal gangue particles which are crushed until the particle size is 18-50 meshes, carbonate mineralizing bacteria, organic solid wastes and an efficient solid composting fermentation inoculant, and then mineralizing a compost substrate by using the mineralization effect of microorganisms. According to the method, the organic nutrients of the artificial soil are increased, and the utilization efficiency of a carbon source in the gangue is activated and improved by adopting a high-efficiency composting fermentation inoculant and a solid aerobic composting fermentation technology. The adsorption performance on heavy metals is improved. In addition, the problems of coal gangue accumulation and soil improvement are solved at the same time, organic solid waste is used as the raw material of the soil conditioner, and double-waste utilization of the coal gangue and the organic solid waste is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral soil fertilizer preparation, and in particular relates to a method for preparing coal gangue artificial soil by utilizing microbial agents. Background Art

[0002] Coal is the main energy source in my country, and the development of coal resources plays an important supporting role in the economic construction and regional development of the Inner Mongolia Autonomous Region. A large amount of coal gangue is produced during coal mining and coal preparation plant operations, accounting for about 15% of coal production. According to statistics, the cumulative amount of gangue in my country currently exceeds 7 billion tons, forming more than 1,500 gangue mountains, covering an area of ​​more than 20 acres, and the emission is increasing year by year at about 500 million to 800 million tons per year. The storage of coal gangue can cause environmental pollution and natural disasters such as spontaneous combustion, acid rain, underground infiltration, silted rivers, photochemical smog and mudslides. Therefore, in the context of ecological civilization construction, facing the severe situation of tightening resource constraints, serious environmental pollution and ecosystem degradation, the treatment and comprehensive utilization of large solid wastes such as coal gangue is a major problem that needs to be solved first.

[0003] Soil is a precious resource for human survival. At present, there is a strong demand for soil in the fields of ecological restoration, desertification control, landscaping, organic agriculture, etc., which leads to widespread illegal soil extraction and damage to a large amount of land. "Tear down the east wall and repair the west wall", where soil is taken, there is destruction. In 2020, my country will completely ban illegal soil extraction. The development of the artificial soil industry fills the gap in the soil market, effectively curbs illegal soil extraction and protects the ecological environment. The country attaches great importance to and actively promotes the development of the artificial soil industry.

[0004] Coal gangue is the product of diagenesis of humus-rich soil from which plants developed in ancient times. It is similar in composition to nutrient soil and has the same characteristics as soil. The mineral composition of the two is similar, both consisting of common clay minerals and other primary minerals. As a companion mineral of coal, coal gangue contains rich humic acid and trace elements required for the growth of various plants. Its mineral composition contains a large amount of clay minerals, which has the potential to increase soil moisture, improve soil carbon storage, and reduce soil fertilizer loss. It is an ideal mineral soil conditioner and nutrient soil development target.

[0005] The use of coal gangue to prepare artificial soil means that the coal gangue is decomposed, activated, passivated and processed by specific microbial activation agents, so that the useful elements contained in the coal gangue are effectively released and can be absorbed by plant growth, playing the role of activating the nutrient reservoir of coal gangue; at the same time, by controlling the particle size composition ratio of coal gangue, the water retention and air permeability of the prepared artificial soil are ensured, thereby forming high-quality artificial soil with the most suitable environment for plant growth. The preparation of artificial soil from coal gangue "turns waste into treasure", which not only solves the problem of large-scale utilization of coal gangue, but also solves the problem of soil supply. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a solid waste-based soil conditioner by utilizing microbial mineralization of coal gangue, which is used to improve poor and arid desert soil, improve the utilization efficiency of gangue carbon sources, increase soil carbon sinks, and consume large amounts of gangue solid waste.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing coal gangue artificial soil by using microbial inoculants, comprising the following steps:

[0009] S1. Crushing coal gangue

[0010] The gangue particles are crushed and sieved to obtain 18-50 mesh gangue particles;

[0011] S2. Determine the maximum water holding capacity of the field

[0012] Several groups of experiments were set up to determine the maximum field water holding capacity of the coal gangue particles prepared by S1;

[0013] S3. Aerobic composting of coal gangue particles

[0014] The coal gangue particles in S1 were used as the matrix, organic solid waste and high-efficiency solid composting fermentation bacteria were added, and the aerobic composting test of coal gangue particles was carried out;

[0015] S4. Biomineralization of compost sludge using microbial agents

[0016] The sludge compost obtained by S3 was used to carry out a biomineralization experiment. The content of calcium carbonate generated was measured to be 12%-15% by an X-ray fluorescence spectrometer test; and a coal gangue solid waste-based soil conditioner was obtained.

[0017] Preferably, in the biomineralization experiment of S4, in order to make the operation closer to the actual environment of the mine, the coal gangue is filled in a columnar mold with a length of 5m, a width of 5m and a height of 1m, wherein the filling height of the coal gangue is 0.8m, and the bacterial solution is added to the liquid inlet pipe of the mold according to 40% of the maximum field water holding capacity. After waiting for 12 hours, the binder liquid is continuously added to the liquid inlet pipe and the liquid inlet wall of the mold until the inner and outer liquid levels are level, and then wait for another 24 hours to obtain the biomineralized coal gangue.

[0018] Preferably, in S4, the method for preparing the bacterial solution is: mixing carbonate mineralizing bacteria with deionized water at an optimal concentration of 1 g / L; preparing LB liquid culture medium by mixing 10 g / L of tryptone, 5 g / L of yeast extract, and 10 g / L of sodium chloride; mixing the mineralizing bacteria with the liquid culture medium, and selecting the bacterial solution cultured for 12 hours for the next experiment by measuring the bacterial solution concentration, urea hydrolysis amount, and bacterial utilization rate.

[0019] Preferably, the method for measuring the concentration of carbonate mineralizing bacteria in the bacterial solution preparation is:

[0020] The number of bacterial cells was determined using an ultraviolet-visible spectrophotometer at a wavelength of 600 nm using the absorbance at a wavelength of 600 nm;

[0021] The formula for calculating the concentration of carbonate mineralizing bacteria is: Y = 8.59 × 10 7 Z 1.3627

[0022] Where, Z is the absorbance of bacterial solution at 600 nanometers in UV-visible spectrophotometer; Y is the concentration of carbonate mineralizing bacteria;

[0023] The calculation formula for the amount of urea hydrolysis in the above bacterial solution preparation is:

[0024] Urea hydrolysis amount mmol / L = conductivity change (ms / cmm) × 11.11.

[0025] Preferably, in S4, a coal gangue with a particle size of 18-50 mesh is selected, and the amount of bacterial solution added is 40%, 60%, and 80% of the field water holding capacity of the coal gangue particles; the bacterial solution concentration is 0.2%. The cementing liquid formula is a mixture of 1.5 mol / L urea and 1.0 mol / L calcium chloride, and the cementing liquid is added until the liquid level submerges the coal gangue, and the biomineralization takes 24 hours. Finally, the biomineralized coal gangue with a calcium carbonate content of 12%-15% is obtained by testing with an X-ray fluorescence spectrometer.

[0026] Preferably, in S3, 60 parts of gangue particles, 25 parts of sheep manure, 15 parts of straw, and high-efficiency solid composting fermentation agent (0.2 kg per ton of material) are fully mixed, water is sprayed on the top of the material while mixing, and the high-efficiency solid composting fermentation agent is added, and then the surface of the substrate is covered with black plastic film. During the composting period, it is necessary to stir for 15 minutes every other day to ensure air circulation and control the temperature between 55°C and 65°C. The material is piled for 35 days. When the temperature of the pile drops to 45°C again, the composting is completed to obtain a sludge compost material with coal gangue as the matrix.

[0027] Preferably, the high-efficiency solid compost fermentation bacterial agent is one or more of silicate bacteria, commercially available EM fermentation bacteria, and special bacteria for coal gangue activation;

[0028] The carbonate mineralizing bacteria agent is Bacillus pasteurianus, with the Latin name Sporosarcina pasteurii. The patent is deposited in the China General Microbiological Culture Collection Center, CGMCC No. 27818. The main function is to hydrolyze urea through the urease produced by microorganisms, change the pH of the system, produce carbonate ions, and then precipitate CaCO3 in the presence of a calcium source, agglomerate small molecular gangue particles, and improve the structure of gangue particles. The mineralized product calcium carbonate (CaCO3) formed can stabilize the harmful metals in the contaminated soil through three mechanisms: adsorption, precipitation conversion and release of carbonate ions, and effectively reduce the mobility of harmful metals in the soil.

[0029] Wherein: the culture medium of the bacterial agent Bacillus pasteurianus is LB culture medium formula: tryptone 10g / L; yeast extract 5g / L; sodium chloride 10g / L. The formula of the cementing liquid required for biomineralization is: urea 1.5mol / L; calcium chloride 1.0mol / L.

[0030] The high-efficiency solid compost fermentation bacterial agent includes silicate bacteria, commercially available EM fermentation bacteria, and special bacteria for coal gangue activation.

[0031] Wherein: the silicate bacteria include: mucilaginous Bacillus and megaterium. Mucilaginous Bacillus: Latin name Bacillus mucilaginosus, purchased from China General Microbiological Culture Collection Center, CGMCC No. 1.9428, the main function is to dissolve potassium, release soluble phosphorus and potassium elements and trace elements such as calcium, sulfur, magnesium, iron, zinc, molybdenum, and manganese; megaterium: Latin name Bacillus megatherium, purchased from China General Microbiological Culture Collection Center, CGMCC No. 1.217, the main function is to dissolve phosphorus, decompose the insoluble phosphorus in the soil, and convert it into phosphorus compounds that can be absorbed by crops, so as to increase the supply of nutrient elements in the soil;

[0032] The commercially available EM fermentation bacteria has an effective bacterial content of ≥10 billion / g, and its main functions are: to rapidly decompose the compost to form a large amount of humus, while converting small molecular nutrients to enrich nutrients, forming soil aggregate structure, regulating soil pH, and promoting soil fertility.

[0033] The special bacteria for gangue activation is Penicillium oxalicum, Latin name: Penicillium oxalicum, purchased from the National General Microbiological Culture Collection Center, CGMCC No. 3.15651, which mainly dissolves the insoluble phosphorus in the gangue, decomposes the gangue, promotes plant growth and increases substrate nutrients and microbial biomass.

[0034] Wherein: the culture medium of the Bacillus mucilaginosus and Bacillus megaterium are both molasses culture medium, specifically composed of: 10g / L tryptone; 1g / L potassium hydrogen phosphate; 700g / L molasses. The culture medium of the oxalicum green plum is a sucrose culture medium, specifically composed of: 100g / L sucrose; 1.6g / L yeast extract powder, 1.5g / L NaNO3, 0.5g / L KH2PO4, 0.025g / LMgSO4·7H2O, 0.025g / L KCl.

[0035] Preferably, the invention also includes a device for mineralizing coal gangue particles with a microbial agent;

[0036] These include molds suitable for in-situ heap leaching processes;

[0037] The mold comprises a plurality of liquid inlet pipes arranged inside the mold and a liquid inlet layer arranged on the inner wall of the mold;

[0038] Or / and, the mold is a container with a length of 5m, a width of 5m and a depth of 1m;

[0039] Or / and, wherein five liquid inlet pipes are respectively arranged at the center and four corners of the mold;

[0040] The inner wall of the liquid inlet pipe is a conical slope, and two rows of liquid inlets with a spacing of 0.01m are opened on the liquid inlet pipe, wherein the conical slope is used to ensure that the bacterial liquid and the cementing liquid are smoothly immersed in the gangue;

[0041] The liquid inlet layer includes at least three rows of liquid inlets with a spacing of 0.14m; the liquid inlet is a circular hole with a radius of 0.01m, and a 50-mesh filter is provided on the liquid inlet to prevent gangue from entering and ensure uniform immersion of the bacterial solution and the cementing liquid.

[0042] Compared with the prior art, the beneficial technical effects of the present invention are:

[0043] First, in terms of technical methods, the present invention adopts green and environmentally friendly carbonate mineralizing bacteria to achieve the dual effects of improving the particle structure of gangue and fixing heavy metals; it adopts high-efficiency composting fermentation bacteria combined with solid aerobic composting fermentation technology to increase the organic nutrients in artificial soil, activate and improve the utilization efficiency of carbon sources in gangue.

[0044] Secondly, in terms of heavy metal adsorption performance, various heavy metal ions rich in the soil can be stably passivated through the cementation mineralization effect of the carbonate mineralizing bacteria of the present invention. The operation is simple, the price is low, and it is easy to promote on site on a large scale.

[0045] Third, in terms of the impact on the environment, the technology of the present invention uses microorganisms and agricultural waste as raw materials throughout the entire process, and "double-waste utilization" of coal gangue and organic solid waste, without adding any chemical reagents. It is a green, ecological, environmentally friendly artificial soil that is suitable for a variety of different environments.

[0046] Fourth, in terms of technical prospects, the present invention is suitable for improving poor and arid soils, increasing the utilization efficiency of gangue carbon sources, increasing soil carbon, and disposing of large amounts of gangue solid waste, and has broad technical prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described below in conjunction with the accompanying drawings.

[0048] Figure 1 It is a top view and structural display of the biomineralized coal gangue mold.

[0049] Figure 2 yes Figure 1 Schematic diagram of the inner wall of the middle mold.

[0050] Figure 3 This is the front view of the biomineralized coal gangue mold.

[0051] Figure 4 It is a schematic diagram of the change of the maximum field water holding capacity of biomineralized coal gangue provided by an embodiment of the present invention;

[0052] Figure 5 This is the front view of the liquid inlet pipe located in the center of the mold.

[0053] Figure 6 This is a graph showing the effect of artificial soil on the germination rate and plant height of alfalfa. DETAILED DESCRIPTION

[0054] Comparing this technology with the existing technology of preparing artificial soil and mineral fertilizer from coal gangue, the current research mainly focuses on preventing heavy metal pollution and promoting plant growth, but most of them pay little attention to the water retention and loss resistance of the soil matrix, which is easy to cause soil erosion problems, resulting in poor sustainability of the restoration effect. The advantages of the present invention are: (1) adding organic solid waste and using high-efficiency composting and fermentation bacteria to accelerate the maturation of modified coal gangue particles, increase the organic fertility of artificial soil of coal gangue, and at the same time, microorganisms can activate inorganic nutrients in modified coal gangue; (2) using carbonate mineralization technology to modify coal gangue particles, change the pore structure of coal gangue particles, improve water holding capacity, and more effectively passivate heavy metals in coal gangue, reducing the heavy metal risk of artificial soil of coal gangue. The following table compares and analyzes the characteristics of the two types of technologies.

[0055] Table 1 Comparative analysis of the characteristics of the present invention and the prior art

[0056]

[0057]

[0058] This embodiment discloses a method for preparing a solid waste-based soil conditioner by utilizing microbial mineralization of coal gangue. The application principle of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0059] S1, crushing coal gangue: crushing and sieving coal gangue particles to obtain coal gangue particles of 18-50 mesh.

[0060] v2. Determine the maximum field water holding capacity: set up three groups of experiments to determine the maximum field water holding capacity of the 18-50 mesh coal gangue particles.

[0061] S3, add biomineralized coal gangue compost fermented into soil with agricultural waste, mix 60 parts of gangue particles, 25 parts of sheep manure, 15 parts of straw, and high-efficiency solid compost fermentation bacteria (0.2kg per ton of material) with a shaking car, spray water on the top of the material while mixing, and add high-efficiency solid compost fermentation bacteria (silicate bacteria, commercially available EM fermentation bacteria, special bacteria for coal gangue activation), and then cover the surface of the substrate with black plastic film. During the composting period, it is necessary to stir for 15 minutes every other day to ensure air circulation and control the temperature between 55℃-65℃. Stack it for about 35 days. When the temperature of the pile drops to 45℃ again, the composting is completed, and the sludge compost material with coal gangue as the matrix is ​​obtained.

[0062] S4, biomineralization treatment of sludge compost using carbonate mineralizing bacteria: biomineralization experiment of sludge compost with coal gangue as matrix, and the content of calcium carbonate generated was 12%-15% through the test of X-ray fluorescence spectrometer. In order to make the operation more in line with the actual environment of the mine, the coal gangue was filled in a columnar mold with a length of 5m, a width of 5m and a height of 1m, and the filling height was 0.8m. Bacterial liquid was added to the mold inlet pipe according to 40% of the maximum field water holding capacity. After waiting for 12 hours, the cementing liquid was continuously added to the mold inlet pipe and the inlet wall until the inner and outer liquid levels were level, and then waited for another 24 hours to obtain the biomineralized coal gangue compost matrix.

[0063] S5, crushing the mineralized coal gangue sludge compost in step 4 into 18-50 meshes to obtain biomineralized coal gangue soil.

[0064] Furthermore, the preparation method of the bacterial solution in the above-mentioned biomineralization experiment is as follows: carbonate mineralizing bacteria are mixed with deionized water at an optimal concentration of 1 g / L; LB liquid culture medium is prepared by mixing 10 g / L of tryptone, 5 g / L of yeast extract, and 10 g / L of sodium chloride; the mineralizing bacteria are mixed with the liquid culture medium, and the bacterial solution that has been cultured for 12 hours is selected for the next experiment by measuring the bacterial solution concentration, urea hydrolysis amount, and bacterial utilization rate.

[0065] Furthermore, the method for measuring the concentration of carbonate mineralizing bacteria and the amount of urea hydrolysis described in the bacterial solution preparation is:

[0066] The number of bacterial cells was determined using an ultraviolet-visible spectrophotometer at a wavelength of 600 nm using the absorbance at a wavelength of 600 nm.

[0067] The formula for calculating the concentration of carbonate mineralizing bacteria is: Y = 8.59 × 10 7 Z 1.3627

[0068] Where: Z is the absorbance of the bacterial culture at 600 nanometers in a UV-visible spectrophotometer, i.e. OD 600 Value; Y is the concentration of carbonate mineralizing bacteria. It is worth noting that only when OD 600 The value of OD is between 0.2 and 0.8, so this formula can be used for conversion. 600 If it exceeds 0.8, the carbonate mineralizing bacteria solution needs to be diluted before conversion.

[0069] Furthermore, the calculation formula for the amount of urea hydrolysis in the above bacterial solution preparation is:

[0070] Urea hydrolysis amount mmmmol / L = conductivity change (ms / cm) × 11.11

[0071] Furthermore, the moisture content of the above organic solid waste (sheep manure, straw) is selected to be 40.-55%.

[0072] Furthermore, the organic solid waste (sheep manure, straw) as the raw material of the biomineralized coal gangue artificial soil plays a role in regulating the composition of organic matter in the humus compost raw material, including the C / N and C / P ratios.

[0073] Furthermore, the organic solid waste (sheep manure, straw) is sorted, dried and crushed to a particle size of 10-20 mm.

[0074] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0075] Embodiment 1:

[0076] Step 1: Select 9 square molds of 7cm*7cm*7cm, add 18-50 mesh coal gangue, and make the coal gangue piled up to 4cm in the mold.

[0077] Step 2: Select the gangue in the three molds to measure the field water holding capacity and porosity. The measurement results are as follows:

[0078] Table 2 Field water holding capacity and pore size of coal gangue

[0079]

[0080] Step 3: Prepare the bacterial solution, adjust the pH value of the prepared LB culture medium to 8.5, sterilize it under high-pressure steam at 120°C for 10 minutes, and after cooling to room temperature, add carbonate mineralizing bacteria powder to make it reach a concentration of 0.2% in the culture medium, then put it into a constant volume bottle and make it up to 300 ml. Place the prepared bacterial solution in a constant temperature shaking incubator and culture it at 25°C at a speed of 200r / min for 12 hours to obtain an activated carbonate mineralizing bacteria solution.

[0081] Step 4: Prepare the binder liquid. Take 5.55g of anhydrous calcium chloride and 45g of urea, and add distilled water to make up to 500ml.

[0082] Step 5: Mix 60 parts of gangue particles, 25 parts of sheep manure, 15 parts of straw, and high-efficiency solid compost fermentation agent (0.2 kg per ton of material) with a shaking car, spray water on the top of the material while mixing, and add high-efficiency solid compost fermentation agent (silicate bacteria, commercially available EM fermentation bacteria, special bacteria for gangue activation). The compost size is 6 meters wide, 6 meters long, and 3 meters high. Cover the surface of the substrate with black plastic film. During the composting period, it is necessary to stir for 15 minutes every other day to ensure air circulation and control the temperature between 55°C and 65°C. Stack it for about 35 days. When the temperature of the pile drops to 45°C again, the composting is completed to obtain a sludge compost raw material with gangue as the matrix.

[0083] Step 7: In order to verify the effect of microbial mineralization on soil pore structure, the activated bacterial solution was poured into 9 square molds filled with coal gangue sludge compost, 18 ml of bacterial solution was added to molds ① to ③, 27 ml of bacterial solution was added to molds ④ to ⑥, and 36 ml of bacterial solution was added to molds ⑦ to ⑨. After standing for 12 hours, the binder was added until the liquid level submerged the coal gangue, where ① to ⑨ are the mold numbers. Then, the molds were allowed to stand for 24 hours to complete the biomineralization experiment and demolded. They were baked in an oven at 60 degrees Celsius for 24 hours until completely dry. Then, the field maximum water holding capacity and porosity of the coal gangue completed by biomineralization with carbonate mineralizing bacteria were measured. The results are shown in the following table.

[0084] Through the analysis of the data, we believe that the use of carbonate mineralizing bacteria to biomineralize coal gangue has changed the pore structure of coal gangue particles. After mineralization, there are more pores than the original pores. The larger pore size is formed by particle accumulation, which has less impact on the overall performance. The smaller pores provide a rich pore structure. Therefore, the mineralized coal gangue has better water retention and loss resistance than the original sample, and can passivate heavy metals more effectively.

[0085] Table 3 Field water holding capacity and pore size of biomineralized coal gangue

[0086]

[0087] Finally, 9 points were selected by multi-point sampling method to measure the microbial biomass carbon, organic carbon, soluble organic carbon, inorganic carbon, nitrogen, phosphorus and potassium contained in the artificial soil, and the results are shown in Table 4. As can be seen from the table, the physical and chemical indicators in the artificial soil are higher than the requirements of organic fertilizer soil, and the microbial content is rich.

[0088] Table 4 Changes of physical and chemical indicators after composting

[0089]

[0090] Embodiment 2:

[0091] In order to illustrate the effect of ecologically improved substrates, soil taken from the coal mining subsidence area of ​​Hongqinghe Coal Mine in Zasak Town, Yijinhuole Banner, Ordos City, Inner Mongolia Autonomous Region was used as the control group. The physical and chemical properties of the soil in the control group are shown in Table 5. A potted experiment was carried out. The experimental group was the artificial soil of the present invention. The plastic gallon pots with specifications of 12.5 cm (pot mouth diameter) × 10 cm (pot bottom diameter) × 11 cm (height) were selected for the experiment. There were three pots in each of the control group and the experimental group. Each pot contained a total of 1 kg of substrate, and each pot was set to 15 alfalfa plants. During the experiment, water was regularly replenished by weighing method to control the soil moisture content at a mild drought level, that is, 75% of the maximum water holding capacity of the test substrate. Natural lighting, no temperature control, and regular exchange of pot positions were used. After 45 days of cultivation, the alfalfa germination rate, plant height, and soil physical and chemical properties were measured. Results are shown in Figure 6 (A, B).

[0092] Table 5 Physical and chemical properties of soil in the control group

[0093]

[0094] Through analysis, it was found that the artificial soil of the present invention had a more obvious promoting effect on seed germination rate and plant height compared with the soil in the control group; in terms of soil physical and chemical properties, the physical and chemical properties of the artificial soil of the present invention were greatly improved compared with those of the soil in the control group. The artificial soil of the present invention is more conducive to plant growth, and has the effect of soil improvement while protecting the environment.

[0095] The above embodiments are only descriptions of the preferred methods of the invention, and are not intended to limit the scope of the invention. Without departing from the design spirit of the invention, various modifications and improvements made to the technical solutions of the invention by ordinary technicians in this field should fall within the protection scope of the claims of the invention.

Claims

1. A method for preparing a solid waste-based soil conditioner by using microbial mineralization of coal gangue, characterized in that: The following steps are involved: S1. Crushing coal gangue The gangue particles are crushed and sieved to obtain 18-50 mesh gangue particles; S2. Determine the maximum water holding capacity of the field Several groups of experiments were set up to determine the maximum field water holding capacity of the coal gangue particles prepared by S1; S3. Aerobic composting of coal gangue particles The coal gangue particles in S1 were used as the matrix, organic solid waste and high-efficiency solid composting fermentation bacteria were added to conduct an aerobic composting experiment on the coal gangue particles. S4. Biomineralization of compost sludge using microbial agents The sludge compost obtained from S3 was used for biomineralization experiments. The content of calcium carbonate generated was 12%-15% as tested by an X-ray fluorescence spectrometer. A solid waste-based soil conditioner of biomineralized coal gangue was obtained. S5. Grinding mineralized coal gangue The mineralized coal gangue in S4 is crushed, filtered, and crushed again to 18-50 meshes to obtain a soil conditioner of biomineralized coal gangue.

2. The method for preparing a solid waste-based soil conditioner by using microbial mineralization of coal gangue according to claim 1, characterized in that: In the biomineralization experiment of S4, in order to make the operation closer to the actual environment of the mine, the coal gangue was filled in a columnar mold with a length of 5m, a width of 5m and a height of 1m, and the filling height of the coal gangue was 0.8m. The bacterial solution was added to the liquid inlet pipe of the mold according to 40% of the maximum field water holding capacity. After waiting for 12 hours, the binder liquid was continuously added to the liquid inlet pipe and the liquid inlet wall of the mold until the inner and outer liquid levels were level. After waiting for another 24 hours, the solid waste-based soil conditioner of biomineralized coal gangue was obtained.

3. The method for preparing a solid waste-based soil conditioner by using microbial mineralization of coal gangue according to claim 2, characterized in that: In S4, the method for preparing the bacterial solution is as follows: carbonate mineralizing bacteria are mixed with deionized water at an optimal concentration of 1 g / L; LB liquid culture medium is prepared by mixing 10 g / L of tryptone, 5 g / L of yeast extract, and 10 g / L of sodium chloride; the mineralizing bacteria are mixed with the liquid culture medium, and the bacterial solution cultured for 12 hours is selected for the next experiment by measuring the bacterial solution concentration, urea hydrolysis amount, and bacterial utilization rate.

4. The method for preparing a solid waste-based soil conditioner by using microbial mineralization of coal gangue according to claim 3, characterized in that: The method for measuring the concentration of carbonate mineralizing bacteria described in the bacterial solution preparation is: The number of bacterial cells was determined using an ultraviolet-visible spectrophotometer at a wavelength of 600 nm using the absorbance at a wavelength of 600 nm; The calculation formula of carbonate mineralizing bacteria concentration is: ; Where, Z is the absorbance of bacterial solution at 600 nanometers in UV-visible spectrophotometer; Y is the concentration of carbonate mineralizing bacteria; The calculation formula for the amount of urea hydrolysis in the above bacterial solution preparation is: Urea hydrolysis amount mmol / L = conductivity change (ms / cm) × 11.

11.

5. The method for preparing a solid waste-based soil conditioner by using microbial mineralization of coal gangue according to claim 2, characterized in that: In S4, the amount of bacterial liquid added was 40%, 60%, and 80% of the field water holding capacity of the gangue particles; the bacterial liquid concentration was 0.2%. The cementing liquid formula was a mixture of 1.5 mol / L urea and 1.0 mol / L calcium chloride. The cementing liquid was added until the liquid surface covered the gangue, and the biomineralization lasted for 24 hours. Finally, the solid waste-based soil conditioner of biomineralized gangue with a calcium carbonate content of 12%-15% was obtained through the test of X-ray fluorescence spectrometer.

6. The method for preparing a solid waste-based soil conditioner by utilizing microbial mineralization of coal gangue according to claim 1, characterized in that: In S3, 60 parts of gangue particles, 25 parts of sheep manure, 15 parts of straw, and high-efficiency solid compost fermentation agent (0.2 kg per ton of material) are fully mixed, water is sprayed on the material while mixing, and high-efficiency solid compost fermentation agent is added, and then the surface of the substrate is covered with black plastic film. During the composting period, it is necessary to stir for 15 minutes every other day to ensure air circulation and control the temperature between 55°C and 65°C. The material is piled for 35 days. When the temperature of the pile drops to 45°C again, the composting is completed to obtain the gangue compost raw material.

7. The method for preparing a solid waste-based soil conditioner by utilizing microbial mineralization of coal gangue according to claim 6, characterized in that: The high-efficiency solid compost fermentation bacterial agent is one or more of silicate bacteria, commercially available EM fermentation bacteria, and special bacteria for coal gangue activation.

8. The method for preparing a solid waste-based soil conditioner by utilizing microbial mineralization of coal gangue according to claim 6, characterized in that: Also included is a device for mineralizing coal gangue particles with carbonate mineralizing bacteria; These include molds suitable for in-situ heap leaching processes; The mold comprises a plurality of liquid inlet pipes arranged inside the mold and a liquid inlet layer arranged on the inner wall of the mold; Or / and, the mold is a container with a length of 5m, a width of 5m and a depth of 1m; Or / and, wherein five liquid inlet pipes are respectively arranged at the center and four corners of the mold; The inner wall of the liquid inlet pipe is a conical slope, and two rows of liquid inlets with a spacing of 0.01m are opened on the liquid inlet pipe, wherein the conical slope is used to ensure that the bacterial liquid and the cementing liquid are smoothly immersed in the gangue; The liquid inlet layer includes at least three rows of liquid inlets with a spacing of 0.14m; the liquid inlet is a circular hole with a radius of 0.01m, and a 50-mesh filter is provided on the liquid inlet to prevent gangue from entering and ensure uniform immersion of the bacterial solution and the cementing liquid.

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