Tailing and microorganism composite jet mortar and preparation method thereof

Abstract

The invention discloses tailing and microorganism composite jet mortar and a preparation method thereof, and belongs to the technical field of microorganism mineralization, heavy metals in the tailing mortar are removed by utilizing a technology of generating calcium carbonate deposition through microorganism induction, and a microbial agent is coated by utilizing sodium alginate microcapsules, so that the tailing and microorganism composite jet mortar is prepared. The microbial agent is immobilized by utilizing the surface porous property and ion exchange capacity of the surface composite calcium-based diatomite to obtain the immobilized enzyme preparation, so that the microbial agent is prevented from being easily lost in mortar pouring; sodium alginate and calcium ions are cross-linked to form a microcapsule structure with a microbial agent as a capsule core, the microcapsule structure is loaded on the composite calcium-based diatomite, the microcapsule structure is formed by cross-linking the center of the calcium ions, carbonate generated by decomposition of urea by microorganisms can react with the calcium ions in the microcapsule, a calcium carbonate layer is deposited on the surface of the microcapsule, and the calcium carbonate layer is formed. The structural strength of the microcapsule is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial mineralization, and specifically relates to a tailings and microbial composite jet mortar and a preparation method thereof. Background Art

[0002] The massive accumulation of gold mine tailings and other tailings not only consumes land resources and increases environmental risks, but their resource utilization is also a key issue for the sustainable development of the mining industry. Using gold mine tailings and other tailings as foundation fill materials in island and reef construction can both reduce waste and lower project costs. However, these tailings are loose and highly porous, and the bearing capacity of the natural foundation often cannot meet actual project requirements. Therefore, reinforcement treatment is required to improve their mechanical properties.

[0003] Among traditional foundation reinforcement methods, physical reinforcement (such as dynamic tamping, soil replacement cushion, cement mixing piles, etc.) requires large-scale equipment support, and faces problems such as long construction period, high cost, and poor site adaptability in tailings foundation treatment; chemical reinforcement is achieved by injecting chemical slurry to achieve solidification, but commonly used materials contain highly alkaline or biotoxic components, which not only pollutes the environment, but also limits the ecological compatibility of the solidified foundation, which is contrary to the concept of green utilization of tailings resources.

[0004] Microbial mineralization technology offers a new direction for tailings foundation reinforcement. Microbial-induced calcium carbonate deposition (MICP) utilizes the metabolic activity of urease-producing bacteria (such as Sporosarcina pasteurii) to hydrolyze urea in a calcium-rich environment to produce carbonate ions. This rapidly precipitates calcium carbonate, which has strong stability and excellent cementing properties. This process fills the pores of the sand particles and aggregates and solidifies the loose tailings sand. This technology offers the advantages of low cost, rapid effectiveness, and environmental friendliness, meeting the demand for green utilization of tailings resources. However, existing MICP technology has significant limitations for tailings sand reinforcement: microorganisms are easily lost with seepage water or groundwater, resulting in reduced mineralization efficiency and affecting the stability of the reinforcement effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a tailings and microbial composite jet mortar and a preparation method thereof, which utilizes microbial-induced calcium carbonate deposition technology to remove heavy metals in the tailings mortar, and utilizes sodium alginate microcapsules to coat the microbial agent. The porous properties and ion exchange capacity of the surface composite calcium-based diatomaceous earth are then utilized to immobilize the microbial agent to obtain an immobilized enzyme preparation, thereby preventing the microbial agent from being easily lost during mortar pouring.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing tailings and microorganism composite jet mortar comprises the following steps: Step 1: The activated diatomite is electrostatically bonded with calcium chloride to achieve chemical immobilization of calcium ions on the surface of the diatomite, thereby obtaining calcium-based diatomite, which is then used as a carrier for hydrothermal synthesis with iron ions to obtain composite calcium-based diatomite.

[0007] Step 2: cross-linking sodium alginate with calcium ions to form a microcapsule structure with a microbial agent as the capsule core, which is loaded on composite calcium-based diatomaceous earth to obtain an immobilized enzyme preparation.

[0008] Step 3: stirring and mixing the urea solution, pretreated calcareous sand and immobilized enzyme preparation to obtain a tailings sand and microorganism composite spray mortar.

[0009] Furthermore, the specific preparation steps of calcium-based diatomaceous earth are as follows: Diatomaceous earth and a sodium bicarbonate solution with a mass fraction of 10-20% are added to a reactor, and vacuum impregnation is carried out at 20-25° C. and 500-600 r / min for 2-4 hours. Then, a calcium chloride solution with a mass fraction of 40-50% is added, and the reaction is continued for 1-2 hours. The mixture is filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and vacuum dried at 60-70° C. for 1-2 hours to obtain calcium-based diatomaceous earth.

[0010] Furthermore, the usage ratio of diatomaceous earth, sodium bicarbonate solution and calcium chloride solution is 1-2 kg: 2-3 L: 500-520 mL.

[0011] Furthermore, the specific preparation steps of composite calcium-based diatomite are as follows: Add 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide solution into a polytetrafluoroethylene-lined autoclave, stir at 20-25°C and 500-600 r / min for 30-40 minutes, then add ferric chloride, heat to 120-130°C, continue to react for 10-12 hours, then add calcium-based diatomaceous earth, continue to react for 10-12 hours, naturally cool to room temperature, filter, wash the filter cake with methanol solution and deionized water for 2-4 times, respectively, and vacuum dry at 60-70°C for 1-2 hours to obtain composite calcium-based diatomaceous earth.

[0012] Furthermore, the usage ratio of 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide solution, ferric chloride and calcium-based diatomaceous earth is 800-900 g: 2-3 L: 500-600 g: 1-2 kg.

[0013] Furthermore, the specific preparation steps of the microbial agent are as follows: The culture medium is prepared using the ATCC 1376 NH4-YE formula recommended by the American Type Culture Collection, and then the culture medium is sterilized at 121-123°C for 20-30 minutes, and then placed on a clean bench for ultraviolet sterilization and ventilation. When the temperature of the culture medium drops to room temperature, the culture medium is taken into a container, and Bacillus pasteurianus is added to the culture medium with a sterile pipette to obtain a bacterial solution, the volume ratio of Bacillus pasteurianus to the culture medium is 1:100, and the bacterial solution is placed in a constant temperature shaking box for cultivation, the constant temperature shaking box temperature is 28-32°C, the oscillation frequency is 200-320r / min, and the cultivation time is 48-72h to obtain a microbial agent.

[0014] Furthermore, the specific preparation steps of the immobilized enzyme preparation are as follows: Sodium alginate and deionized water are added to a reactor, stirred at 20-25°C and 500-600 r / min for 10-12 minutes, and then a microbial agent is added, and stirring is continued for 30-40 minutes to obtain a mixed solution; the mixed solution is dropped into a calcium chloride solution with a mass fraction of 3-4%, and then composite calcium-based diatomaceous earth is added, and stirring is continued for 1-2 hours. The mixture is filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain an immobilized enzyme preparation.

[0015] Furthermore, the usage ratio of sodium alginate, deionized water and microbial agent is 1-2 kg: 2-3 L: 40-50 g.

[0016] Furthermore, the usage ratio of the mixed solution, the calcium chloride solution and the composite calcium-based diatomaceous earth is 800-900 mL: 1-2 L: 1-1.2 kg.

[0017] Furthermore, the specific preparation steps of the tailings and microbial composite spray mortar are as follows: Add urea and deionized water into a reactor, stir at 20-25°C and 500-600 r / min for 10-12 minutes to form a urea solution, then add pretreated calcareous sand and immobilized enzyme preparation, continue stirring for 3-4 hours to obtain a tailings and microorganism composite spray mortar.

[0018] Furthermore, the usage ratio of urea, deionized water, pretreated calcareous sand and immobilized enzyme preparation is 400-450 g: 5-6 L: 1-2 kg: 500-600 g.

[0019] Furthermore, the specific preparation steps of pre-treated calcareous sand are as follows: The calcareous sand was passed through a 2-3 mm sieve, then rinsed in deionized water, and dried in an oven at 60-70° C. for 1-2 h to obtain pretreated calcareous sand.

[0020] Beneficial effects of the present invention: 1. The present invention discloses a tailings and microorganism composite jet mortar, which utilizes microbial-induced calcium carbonate deposition technology to remove heavy metals in the tailings mortar, and utilizes sodium alginate microcapsules to coat the microbial agent. The porous properties and ion exchange capacity of the surface composite calcium-based diatomaceous earth are then utilized to immobilize the microbial agent to obtain an immobilized enzyme preparation, thereby preventing the microbial agent from being easily lost during mortar pouring.

[0021] 2. The composite calcium-based diatomaceous earth of the present invention uses calcium-based bentonite as a carrier to hydrothermally synthesize an iron-based MOF on the surface. The iron-based MOF is loaded on the surface of the calcium-based diatomaceous earth and has high surface energy and abundant hydroxyl groups. It can serve as a heterogeneous nucleation site for calcium carbonate crystallization. The electrostatic attraction between its surface charge and calcium ions reduces the nucleation energy barrier of calcium carbonate and accelerates the formation of crystal nuclei. The iron ions in the iron-based MOF act as electron acceptors to promote extracellular electron transfer of microorganisms and improve the efficiency of microbial-induced carbonate precipitation by accelerating urea hydrolysis and calcium carbonate precipitation. In addition, the ammonia generated by the decomposition of urea can be adsorbed by the composite calcium-based diatomaceous earth.

[0022] 3. The immobilized enzyme preparation of the present invention is formed by cross-linking sodium alginate with calcium ions to form a microcapsule structure with a microbial agent as the capsule core, which is loaded on composite calcium-based diatomaceous earth. The microcapsule structure is cross-linked with calcium ions as the center. The carbonate radicals produced by the decomposition of urea by microorganisms can react with the calcium ions in the microcapsules to deposit a layer of calcium carbonate on the surface of the microcapsules, further improving the structural strength of the microcapsules. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1: A method for preparing a composite jet mortar of tailings and microorganisms, comprising the following steps: S1: Add 1 kg of diatomaceous earth and 2 L of 10% sodium bicarbonate solution into a reactor, vacuum impregnate for 2 h at 20 ° C and 500 r / min, then add 500 mL of 40% calcium chloride solution, continue to react for 1 h, filter, wash the filter cake with deionized water and anhydrous ethanol twice, respectively, and vacuum dry at 60 ° C for 1 h to obtain calcium-based diatomaceous earth.

[0025] S2: Add 800g of 2,5-dihydroxyterephthalic acid and 2L of N,N-dimethylformamide solution into a polytetrafluoroethylene-lined autoclave, stir at 20°C and 500r / min for 30min, then add 500g of ferric chloride, heat to 120°C, continue to react for 10h, then add 1kg of calcium-based diatomaceous earth, continue to react for 10h, naturally cool to room temperature, filter, wash the filter cake twice with methanol solution and deionized water respectively, and dry in vacuo at 60°C for 1h to obtain composite calcium-based diatomaceous earth.

[0026] S3: The culture medium was prepared using the formula ATCC 1376 NH4-YE recommended by the American Type Culture Collection, and then the culture medium was sterilized at 121°C for 20 minutes, and then placed on a clean bench for ultraviolet sterilization and ventilation. When the temperature of the culture medium dropped to room temperature, the culture medium was taken into a container, and Bacillus pasteurianus was added to the culture medium with a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus pasteurianus to the culture medium was 1:100. The bacterial solution was placed in a constant temperature shaking box for cultivation. The temperature of the constant temperature shaking box was 28°C, the oscillation frequency was 200 r / min, and the cultivation time was 48 hours to obtain a microbial agent.

[0027] S4: Add 1 kg of sodium alginate and 2 L of deionized water into the reactor, stir at 20 ° C and 500 r / min for 10 minutes, then add 40 g of microbial agent, continue stirring for 30 minutes to obtain a mixed solution; drop 800 mL of the mixed solution into 1 L of 3% calcium chloride solution, then add 1 kg of composite calcium-based diatomaceous earth, continue stirring for 1 hour, filter, wash the filter cake with deionized water and anhydrous ethanol twice respectively, and vacuum dry at 60 ° C for 1 hour to obtain an immobilized enzyme preparation.

[0028] S5: The calcareous sand was sieved with 2 mm sieve, rinsed with deionized water, and dried in an oven at 60°C for 1 h to obtain pretreated calcareous sand; 400 g of urea and 5 L of deionized water were added to a reactor, stirred at 20°C and 500 r / min for 10 min to form a urea solution, and then 1 kg of pretreated calcareous sand and 500 g of immobilized enzyme preparation were added, and stirring was continued for 3 h to obtain a tailings and microorganism composite spray mortar.

[0029] Example 2: A method for preparing a composite jet mortar of tailings and microorganisms, comprising the following steps: S1: 1.5 kg of diatomaceous earth and 2.5 L of 15% sodium bicarbonate solution were added to the reactor, and vacuum impregnation was carried out at 22.5 ° C and 550 r / min for 3 h. Then 510 mL of 45% calcium chloride solution was added and the reaction was continued for 1.5 h. The mixture was filtered and the filter cake was washed with deionized water and anhydrous ethanol three times respectively, and vacuum dried at 65 ° C for 1.5 h to obtain calcium-based diatomaceous earth.

[0030] S2: Add 850g of 2,5-dihydroxyterephthalic acid and 2.5L of N,N-dimethylformamide solution into a polytetrafluoroethylene-lined autoclave, stir at 22.5°C and 550r / min for 35min, then add 550g of ferric chloride, heat to 125°C, continue to react for 11h, then add 1.5kg of calcium-based diatomaceous earth, continue to react for 11h, naturally cool to room temperature, filter, wash the filter cake with methanol solution and deionized water three times respectively, and dry in vacuo at 65°C for 1.5h to obtain composite calcium-based diatomaceous earth.

[0031] S3: The culture medium was prepared using the formula ATCC 1376 NH4-YE recommended by the American Type Culture Collection, and then the culture medium was sterilized at 122°C for 25 minutes, and then placed on a clean bench for UV sterilization and ventilation. When the temperature of the culture medium dropped to room temperature, the culture medium was taken into a container, and Bacillus pasteurianus was added to the culture medium with a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus pasteurianus to the culture medium was 1:100. The bacterial solution was placed in a constant temperature shaking box for cultivation. The temperature of the constant temperature shaking box was 30°C, the oscillation frequency was 260 r / min, and the cultivation time was 60 hours to obtain a microbial agent.

[0032] S4: Add 1.5 kg of sodium alginate and 2.5 L of deionized water into the reactor, stir for 11 min at 22.5 °C and 550 r / min, then add 45 g of microbial agent and continue stirring for 35 min to obtain a mixed solution; drop 850 mL of the mixed solution into 1.5 L of 3.5% calcium chloride solution, then add 1.1 kg of composite calcium-based diatomaceous earth, continue stirring for 1.5 h, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, and vacuum dry at 65 °C for 1.5 h to obtain an immobilized enzyme preparation.

[0033] S5: The calcareous sand was passed through a 2.5 mm sieve, then rinsed with deionized water, and dried in an oven at 65°C for 1.5 h to obtain pretreated calcareous sand; 425 g of urea and 5.5 L of deionized water were added to a reactor, stirred at 22.5°C and 550 r / min for 11 min to form a urea solution, and then 1.5 kg of pretreated calcareous sand and 550 g of immobilized enzyme preparation were added, and stirring was continued for 3.5 h to obtain a tailings and microbial composite spray mortar.

[0034] Example 3: A method for preparing a composite jet mortar of tailings and microorganisms, comprising the following steps: S1: 2 kg of diatomaceous earth and 3 L of 20% sodium bicarbonate solution were added to a reactor, and vacuum impregnation was carried out at 25 ° C and 600 r / min for 4 h. Then 520 mL of 50% calcium chloride solution was added and the reaction was continued for 2 h. The filter cake was washed with deionized water and anhydrous ethanol four times respectively, and vacuum dried at 70 ° C for 2 h to obtain calcium-based diatomaceous earth.

[0035] S2: Add 900g of 2,5-dihydroxyterephthalic acid and 3L of N,N-dimethylformamide solution into a polytetrafluoroethylene-lined autoclave, stir at 25°C and 600r / min for 40min, then add 600g of ferric chloride, heat to 130°C, continue to react for 12h, then add 2kg of calcium-based diatomaceous earth, continue to react for 12h, naturally cool to room temperature, filter, wash the filter cake with methanol solution and deionized water four times respectively, and dry in vacuo at 70°C for 2h to obtain composite calcium-based diatomaceous earth.

[0036] S3: The culture medium was prepared using the formula ATCC 1376 NH4-YE recommended by the American Type Culture Collection, and then the culture medium was sterilized at 123°C for 30 minutes, and then placed on a clean bench for ultraviolet sterilization and ventilation. When the temperature of the culture medium dropped to room temperature, the culture medium was taken into a container, and Bacillus pasteurianus was added to the culture medium with a sterile pipette to obtain a bacterial solution. The volume ratio of Bacillus pasteurianus to the culture medium was 1:100. The bacterial solution was placed in a constant temperature shaking box for cultivation. The temperature of the constant temperature shaking box was 32°C, the oscillation frequency was 320 r / min, and the cultivation time was 72 hours to obtain a microbial agent.

[0037] S4: Add 2 kg of sodium alginate and 3 L of deionized water into the reactor, stir at 25 ° C and 600 r / min for 12 minutes, then add 50 g of microbial agent, continue stirring for 40 minutes to obtain a mixed solution; drop 900 mL of the mixed solution into 2 L of 4% calcium chloride solution, then add 1.2 kg of composite calcium-based diatomaceous earth, continue stirring for 2 hours, filter, wash the filter cake with deionized water and anhydrous ethanol four times respectively, and vacuum dry at 70 ° C for 2 hours to obtain an immobilized enzyme preparation.

[0038] S5: The calcareous sand was passed through a 3 mm sieve, then rinsed with deionized water, and dried in an oven at 70°C for 2 h to obtain pretreated calcareous sand; 450 g of urea and 6 L of deionized water were added to a reactor, stirred at 25°C and 600 r / min for 12 min to form a urea solution, and then 2 kg of pretreated calcareous sand and 600 g of immobilized enzyme preparation were added, and stirring was continued for 4 h to obtain a tailings and microorganism composite spray mortar.

[0039] Comparative Example 1: Based on Example 3, the calcium-based diatomaceous earth in step S2 is replaced by diatomaceous earth in step S1.

[0040] Comparative Example 2: Based on Example 3, the composite calcium-based diatomaceous earth in step S4 is replaced by the calcium-based diatomaceous earth prepared in step S1.

[0041] Comparative Example 3: Based on Example 3, the immobilized enzyme preparation in step S5 was replaced by the composite calcium-based diatomaceous earth prepared in step S2.

[0042] The performance tests of Examples 1 to 3 and Comparative Examples 1 to 3 were carried out. The tailings and microbial composite spray mortar prepared in the Examples and Comparative Examples were placed in a test mold and cured for 7 days at 23°C and 60% relative humidity to form a 40×40×160 mm 3 The samples were uniformly loaded at a rate of 2500N / S to test the compressive strength; the test was carried out with reference to the process of the anti-seepage performance test in JGJ / T-2009 "Standard for Test Methods for Basic Properties of Building Mortar", where the curing time after demoulding was 14 days, and the maximum pressure during water seepage was obtained.

[0043] Heavy metal content analysis (testing for manganese and copper): The tailings and microbial composite spray mortar was crushed and sieved, 5g was placed in a test tube, and 25ml of deionized water was added. The mixture was shaken thoroughly for 5 minutes. After standing for 4 days, the supernatant was collected and the heavy metal content in the supernatant was tested using coupled plasma optical emission spectroscopy (ICP-OES, lower limit of measurement: 0.001mg / L). The results are shown in Table 1: Table 1 Performance test data of composite spraying mortar project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Compressive strength (MPa) 36.5 37.8 38.2 24.3 18.7 19.6 Impermeability pressure (MPa) 2.39 2.45 2.52 1.42 0.85 0.93 Manganese removal rate (%) 62.2 63.5 64.3 56.2 50.7 48.8 Copper removal rate (%) 85.6 86.3 87.2 71.2 65.2 63.4 As can be seen from Table 1, the compressive strength and anti-seepage pressure of the tailings and microorganism composite spraying mortars of Examples 1 to 3 are significantly better than those of the comparative example, indicating that the tailings and microorganism composite spraying mortar prepared by the present invention has excellent compressive resistance and anti-seepage performance, and has a good removal effect on heavy metals.

[0044] The calcium-based diatomaceous earth in Comparative Example 1 was replaced by the diatomaceous earth in step S1, and the immobilization of microorganisms failed. The original diatomaceous earth was not activated by calcium ions, and the surface lacked calcium ion exchange sites, making it impossible to stably adsorb sodium alginate microcapsules through electrostatic action. The cross-linking of sodium alginate depends on calcium ions, and the original diatomaceous earth has no calcium-based active sites, resulting in a lower microcapsule molding rate and an increased microbial leakage rate.

[0045] In Comparative Example 2, the composite calcium-based diatomite is replaced with the calcium-based diatomite prepared in step S1. The heterogeneous nucleation ability is lost. The calcium-based diatomite lacks iron MOF and cannot provide lattice matching sites for calcium carbonate crystallization, resulting in reduced strength. The lack of iron-based MOF leads to a decrease in extracellular electron transfer efficiency, a slowdown in urea hydrolysis rate, and a decrease in calcium carbonate deposition rate.

[0046] In Comparative Example 3, the immobilized enzyme preparation was replaced with the composite calcium-based diatomaceous earth prepared in S2. The composite calcium-based diatomaceous earth was not coated with sodium alginate microcapsules. The microorganisms were destroyed by the shear force of the water flow during the mortar stirring and spraying process, and the loss rate increased. The ammonia produced by the decomposition of urea could not be slowly released and adsorbed by the microcapsules, the local pH increased, the urease activity was inhibited, and the calcium carbonate deposition was uneven.

[0047] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing tailings and microorganism composite jet mortar, characterized in that: The steps include: Step 1: Calcium chloride is electrostatically bonded to the activated diatomite to chemically immobilize calcium ions on the surface of the diatomite, thereby obtaining calcium-based diatomite, which is then used as a carrier for hydrothermal synthesis with iron ions to obtain composite calcium-based diatomite; Step 2: cross-linking sodium alginate with calcium ions to form a microcapsule structure with a microbial agent as the capsule core, which is loaded on composite calcium-based diatomaceous earth to obtain an immobilized enzyme preparation; Step 3: stirring and mixing the urea solution, pretreated calcareous sand and immobilized enzyme preparation to obtain a tailings sand and microorganism composite spray mortar.

2. The method for preparing a tailings and microorganism composite jet mortar according to claim 1, characterized in that: The specific preparation steps of the calcium-based diatomaceous earth are as follows: Diatomaceous earth and a sodium bicarbonate solution with a mass fraction of 10-20% are added to a reactor, and vacuum impregnation is carried out at 20-25° C. and 500-600 r / min for 2-4 hours. Then, a calcium chloride solution with a mass fraction of 40-50% is added, and the reaction is continued for 1-2 hours. The mixture is filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and vacuum dried at 60-70° C. for 1-2 hours to obtain calcium-based diatomaceous earth.

3. The method for preparing a tailings and microorganism composite jet mortar according to claim 2, characterized in that: The usage ratio of the diatomaceous earth, sodium bicarbonate solution and calcium chloride solution is 1-2 kg: 2-3 L: 500-520 mL.

4. The method for preparing a tailings and microorganism composite jet mortar according to claim 1, characterized in that: The specific preparation steps of the composite calcium-based diatomaceous earth are as follows: Add 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide solution into a polytetrafluoroethylene-lined autoclave, stir at 20-25°C and 500-600 r / min for 30-40 minutes, then add ferric chloride, heat to 120-130°C, continue to react for 10-12 hours, then add calcium-based diatomaceous earth, continue to react for 10-12 hours, naturally cool to room temperature, filter, wash the filter cake with methanol solution and deionized water for 2-4 times, respectively, and vacuum dry at 60-70°C for 1-2 hours to obtain composite calcium-based diatomaceous earth.

5. The method for preparing a tailings and microorganism composite jet mortar according to claim 4, characterized in that: The usage ratio of the 2,5-dihydroxyterephthalic acid, N,N-dimethylformamide solution, ferric chloride and calcium-based diatomaceous earth is 800-900 g: 2-3 L: 500-600 g: 1-2 kg.

6. The method for preparing a tailings and microorganism composite jet mortar according to claim 1, characterized in that: The specific preparation steps of the microbial agent are as follows: The culture medium is prepared using the ATCC 1376 NH4-YE formula recommended by the American Type Culture Collection, and then the culture medium is sterilized at 121-123°C for 20-30 minutes, and then placed on a clean bench for ultraviolet sterilization and ventilation. When the temperature of the culture medium drops to room temperature, the culture medium is taken into a container, and Bacillus pasteurianus is added to the culture medium with a sterile pipette to obtain a bacterial solution, the volume ratio of Bacillus pasteurianus to the culture medium is 1:100, and the bacterial solution is placed in a constant temperature shaking box for cultivation, the constant temperature shaking box temperature is 28-32°C, the oscillation frequency is 200-320r / min, and the cultivation time is 48-72h to obtain a microbial agent.

7. The method for preparing a tailings and microorganism composite jet mortar according to claim 1, characterized in that: The specific preparation steps of the immobilized enzyme preparation are as follows: Sodium alginate and deionized water are added to a reactor, stirred at 20-25°C and 500-600 r / min for 10-12 minutes, and then a microbial agent is added, and stirring is continued for 30-40 minutes to obtain a mixed solution; the mixed solution is dropped into a 3-4% by mass calcium chloride solution, and then composite calcium-based diatomaceous earth is added, and stirring is continued for 1-2 hours, filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain an immobilized enzyme preparation; The dosage ratio of the sodium alginate, deionized water and microbial agent is 1-2 kg: 2-3 L: 40-50 g; the dosage ratio of the mixed solution, calcium chloride solution and composite calcium-based diatomaceous earth is 800-900 mL: 1-2 L: 1-1.2 kg.

8. The method for preparing a tailings and microorganism composite jet mortar according to claim 1, characterized in that: The specific preparation steps of the tailings and microbial composite jet mortar are as follows: Add urea and deionized water into a reactor, stir at 20-25°C and 500-600 r / min for 10-12 minutes to form a urea solution, then add pretreated calcareous sand and immobilized enzyme preparation, continue stirring for 3-4 hours, and obtain a tailings and microorganism composite spray mortar; The usage ratio of the urea, deionized water, pretreated calcareous sand and immobilized enzyme preparation is 400-450 g: 5-6 L: 1-2 kg: 500-600 g.

9. The method for preparing a tailings and microorganism composite jet mortar according to claim 8, characterized in that: The specific preparation steps for pre-treated calcareous sand are as follows: The calcareous sand was passed through a 2-3 mm sieve, then rinsed in deionized water, and dried in an oven at 60-70° C. for 1-2 h to obtain pretreated calcareous sand.

10. A tailings and microorganism composite jet mortar, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.