Tailings and microorganism composite injection mortar and preparation method thereof

Abstract

The application discloses tailings and microbial composite injection mortar and a preparation method thereof, and belongs to the technical field of microbial mineralization. The calcium carbonate deposition technology induced by microorganisms is used to remove heavy metals in tailings mortar. The microbial inoculum is coated by sodium alginate microcapsules. The microbial inoculum is fixed by using the porous properties and ion exchange capacity of the surface composite calcium-based diatomite surface. The immobilized enzyme preparation is obtained, so that the microbial inoculum is prevented from being lost easily in mortar pouring. The sodium alginate and calcium ions are crosslinked to form a microcapsule structure with the microbial inoculum as a capsule core, and the microcapsule structure is crosslinked with calcium ions as the center. The calcium carbonate layer is deposited on the surface of the microcapsule by the reaction between the calcium ions in the microcapsule and the carbonate generated by the decomposition of urea by the microorganism, so that the structural strength of the microcapsule is further improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microbial mineralization, and particularly relates to tailing sand and microbial composite sprayed mortar and a preparation method thereof. BACKGROUND

[0002] Large amounts of tailings such as gold mine tailings are not only land resources and increase environmental risks, but also resource utilization is an important issue for the sustainable development of the current mineral industry. The tailings such as gold mine tailings can be used as foundation filling materials in island reclamation, which not only realizes waste reduction, but also reduces engineering cost. However, the loose tailings sand has high porosity, and the natural foundation bearing capacity often cannot meet the actual engineering requirements, so the mechanical properties need to be improved through reinforcement.

[0003] In the traditional foundation reinforcement method, physical reinforcement (such as dynamic compaction, soil replacement cushion, cement mixing pile, etc.) needs large equipment support, and has problems such as long construction period, high cost and poor site adaptability in tailings foundation treatment; chemical reinforcement is achieved by pouring chemical slurry, but the commonly used materials contain strong alkaline or biological toxic components, which not only pollute the environment, but also limit the ecological compatibility of the solidified foundation, which is contrary to the concept of green utilization of tailings resources.

[0004] Microbial mineralization technology provides a new direction for tailings foundation reinforcement. Among them, microbial induced calcium carbonate precipitation (MICP) utilizes the metabolic action of urease-producing bacteria (such as Bacillus pasteurii) to hydrolyze urea to generate carbonate in an environment rich in calcium ions, and quickly precipitates calcium carbonate with strong stability and excellent cementation performance, which agglomerates and solidifies loose tailings sand by filling sand particle pores, and has the advantages of low cost, quick effect and environmental friendliness, which meets the green utilization demand of tailings resources. However, the existing MICP technology has obvious limitations in tailings sand reinforcement: the microorganisms are easy to flow and lose with the seepage water or groundwater, which reduces the mineralization efficiency and affects the stability of the reinforcement effect. SUMMARY

[0005] The purpose of the present application is to provide a tail sand and microbial composite sprayed mortar and a preparation method thereof, which utilizes microbial induced calcium carbonate deposition technology to remove heavy metals in tail sand mortar, and utilizes sodium alginate microcapsules to coat microbial agents, and then utilizes the surface composite calcium-based diatomite surface porosity and ion exchange capacity to fix the microbial agents, to obtain immobilized enzyme preparation, so as to avoid the loss of microbial agents in the mortar pouring.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A preparation method of tail sand and microbial composite sprayed mortar, comprising the following steps:

[0008] Step one: through the electrostatic effect of calcium chloride and activated diatomite, realize the chemical immobilization of calcium ions on the surface of diatomite, and obtain calcium-based diatomite, and then hydrothermally synthesize composite calcium-based diatomite by taking the calcium-based diatomite as a carrier and iron ions.

[0009] Step two: crosslink sodium alginate and calcium ions to form a microcapsule structure with a microbial agent as a core, and load the microcapsule structure on the composite calcium-based diatomite to obtain an immobilized enzyme preparation.

[0010] Step three: mix urea solution, pretreated calcium sand, and immobilized enzyme preparation by stirring to obtain a tailing sand and microbial composite injection mortar.

[0011] Further, the specific preparation steps of the calcium-based diatomite are as follows:

[0012] The diatomite and a sodium bicarbonate solution with a mass fraction of 10-20% are added to a reaction kettle, vacuum impregnated at 20-25℃ and 500-600r / min for 2-4h, then a calcium chloride solution with a mass fraction of 40-50% is added, and the reaction is continued for 1-2h, the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dried at 60-70℃ for 1-2h to obtain the calcium-based diatomite.

[0013] Further, the amount ratio of the diatomite, the sodium bicarbonate solution, and the calcium chloride solution is 1-2kg:2-3L:500-520mL.

[0014] Further, the specific preparation steps of the composite calcium-based diatomite are as follows:

[0015] The 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide solution are added to a polytetrafluoroethylene-lined autoclave, stirred at 20-25℃ and 500-600r / min for 30-40min, then iron chloride is added, heated to 120-130℃, and the reaction is continued for 10-12h, then the calcium-based diatomite is added, and the reaction is continued for 10-12h, and then the mixture is naturally cooled to room temperature, filtered, and the filter cake is washed with methanol solution and deionized water for 2-4 times respectively, and vacuum dried at 60-70℃ for 1-2h to obtain the composite calcium-based diatomite.

[0016] Further, the amount ratio of the 2,5-dihydroxyterephthalic acid, the N,N-dimethylformamide solution, the iron chloride, and the calcium-based diatomite is 800-900g:2-3L:500-600g:1-2kg.

[0017] Further, the specific preparation steps of the microbial agent are as follows:

[0018] The culture solution is prepared by using the formula ATCC 1376 NH4-YE recommended by the American Type Culture Collection, and then the culture solution is sterilized at 121-123 ℃ for 20-30 min, placed on an ultraclean workbench for ultraviolet sterilization and ventilation, and when the temperature of the culture solution is reduced to room temperature, the culture solution is taken in a container, and the Bacillus pasteurii is added into the culture solution by using a sterile pipette to obtain a bacterial solution, and the volume ratio of the Bacillus pasteurii to the culture solution is 1:100, and the bacterial solution is placed in a constant-temperature shaking incubator for culture, the temperature of the constant-temperature shaking incubator is 28-32 ℃, the shaking frequency is 200-320 r / min, and the culture time is 48-72 h, so as to obtain the microbial inoculum.

[0019] Further, the specific preparation steps of the immobilized enzyme preparation are as follows:

[0020] The sodium alginate and deionized water are added into a reaction kettle, stirred at 20-25 ℃ and 500-600 r / min for 10-12 min, then the microbial inoculum is added, and the stirring is continued for 30-40 min to obtain a mixed solution; the mixed solution is dropped into a calcium chloride solution with a mass fraction of 3-4%, then the composite calcium-based diatomite is added, and the stirring is continued for 1-2 h, and then the filter cake is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dried at 60-70 ℃ for 1-2 h to obtain the immobilized enzyme preparation.

[0021] Further, the amount ratio of the sodium alginate, the deionized water and the microbial inoculum is 1-2 kg:2-3 L:40-50 g.

[0022] Further, the amount ratio of the mixed solution, the calcium chloride solution and the composite calcium-based diatomite is 800-900 mL:1-2 L:1-1.2 kg.

[0023] Further, the specific preparation steps of the tailings and microbial composite sprayed mortar are as follows:

[0024] The urea and deionized water are added into a reaction kettle, stirred at 20-25 ℃ and 500-600 r / min for 10-12 min to form a urea solution, then the pretreated calcareous sand and the immobilized enzyme preparation are added, and the stirring is continued for 3-4 h to obtain a tailings and microbial composite sprayed mortar.

[0025] Further, the amount ratio of the urea, the deionized water, the pretreated calcareous sand and the immobilized enzyme preparation is 400-450 g:5-6 L:1-2 kg:500-600 g.

[0026] Further, the specific preparation steps of the pretreated calcareous sand are as follows:

[0027] The calcareous sand is passed through a 2-3 mm sieve, then rinsed in deionized water, and placed in an oven for drying at 60-70 ℃ for 1-2 h to obtain the pretreated calcareous sand.

[0028] Advantages of the present application:

[0029] 1. The tailings and microorganism composite sprayed mortar of the present application uses the microorganism-induced calcium carbonate deposition technology to remove heavy metals in the tailings mortar, and uses sodium alginate microcapsules to coat the microorganist agents, and then uses the surface composite calcium-based diatomite surface porosity and ion exchange capacity to fix the microorganism agents to obtain immobilized enzyme preparation, thereby avoiding the loss of microorganism agents in the mortar pouring.

[0030] 2. The composite calcium-based diatomite of the present application uses calcium-based bentonite as a carrier, and surface hydrothermal synthesis iron-based MOF, which is loaded on the surface of the calcium-based diatomite, has high surface energy and abundant hydroxyl groups, and can be used as a heterogeneous nucleation site for calcium carbonate crystallization. The surface charge and the electrostatic attraction of calcium ions reduce the nucleation energy barrier of calcium carbonate and accelerate the formation of crystal nucleus. The iron ions in the iron-based MOF act as electron acceptors to promote extracellular electron transfer of microorganisms, and accelerate urea hydrolysis and calcium carbonate precipitation to improve the efficiency of microorganism-induced carbonate precipitation. In addition, the ammonia gas produced by urea decomposition can be adsorbed by the composite calcium-based diatomite.

[0031] 3. The immobilized enzyme preparation of the present application loads the microcapsule structure with microorganism agents as the core on the composite calcium-based diatomite by cross-linking sodium alginate with calcium ions. The microcapsule structure is cross-linked with calcium ions as the center. The carbonate produced by the decomposition of urea by microorganisms can react with the calcium ions in the microcapsule to deposit a layer of calcium carbonate on the surface of the microcapsule, further improving the structural strength of the microcapsule. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] Embodiment 1: A preparation method of a tailings and microorganism composite sprayed mortar, comprising the following steps:

[0034] S1: 1 kg of diatomite, 2 L of 10% mass fraction sodium bicarbonate solution are added to a reaction kettle, vacuum impregnated at 20℃ and 500 r / min for 2 h, then 500 mL of 40% mass fraction calcium chloride solution is added, and the reaction is continued for 1 h. The filter cake is washed with deionized water and anhydrous ethanol for 2 times respectively, and vacuum dried at 60℃ for 1 h to obtain calcium-based diatomite.

[0035] S2: 800g 2,5-dihydroxyterephthalic acid and 2L N,N-dimethylformamide solution were added into a polytetrafluoroethylene lined autoclave, stirred at 20℃ and 500r / min for 30min, then 500g iron chloride was added, heated to 120℃, and reacted for 10h, then 1kg calcium-based diatomite was added, and reacted for 10h, naturally cooled to room temperature, filtered, the filter cake was washed with methanol solution and deionized water for 2 times respectively, and vacuum dried at 60℃ for 1h, to obtain a composite calcium-based diatomite.

[0036] S3: A culture solution was prepared according to the recommended formula ATCC 1376 NH4-YE of American Type Culture Collection, then the culture solution was sterilized at 121℃ for 20min, placed on an ultraclean bench for ultraviolet sterilization and ventilation, when the temperature of the culture solution was reduced to room temperature, the culture solution was taken in a container, and the Bacillus pasteurii was added into the culture solution by a sterile pipette to obtain a bacterial solution, the volume ratio of Bacillus pasteurii to the culture solution was 1:100, the bacterial solution was placed in a constant temperature shaking incubator, the temperature of the constant temperature shaking incubator was 28℃, the shaking frequency was 200r / min, and the culture time was 48h, to obtain a microbial inoculant.

[0037] S4: 1kg sodium alginate and 2L deionized water were added into a reaction kettle, stirred at 20℃ and 500r / min for 10min, then 40g microbial inoculant was added, and stirred for 30min to obtain a mixed solution; 800mL of the mixed solution was dropped into 1L calcium chloride solution with a mass fraction of 3%, then 1kg composite calcium-based diatomite was added, and stirred for 1h, filtered, the filter cake was washed with deionized water and anhydrous ethanol for 2 times respectively, and vacuum dried at 60℃ for 1h, to obtain an immobilized enzyme preparation.

[0038] S5: The calcareous sand was passed through a 2mm sieve, then rinsed under deionized water, and dried in an oven at 60℃ for 1h, to obtain pretreated calcareous sand; 400g urea and 5L deionized water were added into a reaction kettle, stirred at 20℃ and 500r / min for 10min to form a urea solution, then 1kg pretreated calcareous sand and 500g immobilized enzyme preparation were added, and stirred for 3h, to obtain a tailings and microbial composite injection mortar.

[0039] Example 2: A preparation method of a tailings and microbial composite injection mortar, comprising the following steps:

[0040] S1: 1.5 kg of diatomite, 2.5 L of a 15% by mass sodium bicarbonate solution were added to a reaction kettle, vacuum impregnated at 22.5°C and 550 r / min for 3 h, then 510 mL of a 45% by mass calcium chloride solution was added, and the reaction was continued for 1.5 h, then the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain calcium-based diatomite.

[0041] S2: 850 g of 2,5-dihydroxyterephthalic acid and 2.5 L of N,N-dimethylformamide solution were added to a polytetrafluoroethylene-lined autoclave, stirred at 22.5°C and 550 r / min for 35 min, then 550 g of iron chloride was added, heated to 125°C, and the reaction was continued for 11 h, then 1.5 kg of calcium-based diatomite was added, and the reaction was continued for 11 h, then it was naturally cooled to room temperature, filtered, and the filter cake was washed with methanol solution and deionized water for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain composite calcium-based diatomite.

[0042] S3: The culture solution was prepared by using the recommended formula ATCC 1376 NH4-YE of American Type Culture Collection, then the culture solution was sterilized at 122°C for 25 min, then it was placed on an ultra-clean bench for ultraviolet sterilization and ventilation, when the temperature of the culture solution was reduced to room temperature, the culture solution was taken in a container, and the Bacillus pasteurii was added into the culture solution by using a sterile pipette to obtain a bacterial solution, the volume ratio of Bacillus pasteurii to the culture solution was 1:100, the bacterial solution was placed in a constant temperature shaking incubator, the temperature of the constant temperature shaking incubator was 30°C, the shaking frequency was 260 r / min, and the culture time was 60 h to obtain a microbial inoculant.

[0043] S4: 1.5 kg of sodium alginate and 2.5 L of deionized water were added to a reaction kettle, stirred at 22.5°C and 550 r / min for 11 min, then 45 g of the microbial inoculant was added, and the stirring was continued for 35 min to obtain a mixed solution; 850 mL of the mixed solution was dropped into 1.5 L of a 3.5% by mass calcium chloride solution, then 1.1 kg of composite calcium-based diatomite was added, and the stirring was continued for 1.5 h, then it was filtered, the filter cake was washed with deionized water and anhydrous ethanol for 3 times respectively, and vacuum dried at 65°C for 1.5 h to obtain an immobilized enzyme preparation.

[0044] S5: The calcareous sand was passed through a 2.5 mm sieve, then it was rinsed under 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 reaction kettle, stirred at 22.5°C and 550 r / min for 11 min to form a urea solution, then 1.5 kg of pretreated calcareous sand and 550 g of immobilized enzyme preparation were added, and the stirring was continued for 3.5 h to obtain a tailings and microbial composite injection mortar.

[0045] Embodiment 3: A preparation method of tailings and microbial composite injection mortar, comprising the following steps:

[0046] S1: 2 kg of diatomite, 3 L of 20% by mass sodium bicarbonate solution were added into a reaction kettle, vacuum impregnated at 25°C and 600 r / min for 4 h, then 520 mL of 50% by mass calcium chloride solution was added, and the reaction was continued for 2 h, and the filter cake was washed with deionized water and anhydrous ethanol for 4 times respectively, and vacuum dried at 70°C for 2 h to obtain calcium-based diatomite.

[0047] S2: 900 g of 2,5-dihydroxyterephthalic acid and 3 L of N,N-dimethylformamide solution were added into a polytetrafluoroethylene lined autoclave, stirred at 25°C and 600 r / min for 40 min, then 600 g of iron chloride was added, heated to 130°C, and the reaction was continued for 12 h, then 2 kg of calcium-based diatomite was added, and the reaction was continued for 12 h, and then naturally cooled to room temperature, filtered, and the filter cake was washed with methanol solution and deionized water for 4 times respectively, and vacuum dried at 70°C for 2 h to obtain composite calcium-based diatomite.

[0048] S3: The culture solution was prepared according to the recommended formula ATCC 1376 NH4-YE of American Type Culture Collection, then sterilized at 123°C for 30 min, placed on an ultra-clean bench for ultraviolet sterilization and ventilation, and when the temperature of the culture solution decreased to room temperature, the culture solution was taken into a container, and the Bacillus pasteurii was added into the culture solution by a sterile pipette to obtain a bacterial solution, the volume ratio of Bacillus pasteurii to the culture solution was 1:100, the bacterial solution was placed in a constant temperature shaking incubator, the temperature of the constant temperature shaking incubator was 32°C, the shaking frequency was 320 r / min, and the culture time was 72 h to obtain a microbial inoculant.

[0049] S4: 2 kg of sodium alginate and 3 L of deionized water were added into a reaction kettle, stirred at 25°C and 600 r / min for 12 min, then 50 g of microbial inoculant was added, and the stirring was continued for 40 min to obtain a mixed solution; 900 mL of the mixed solution was dropped into 2 L of 4% by mass calcium chloride solution, then 1.2 kg of composite calcium-based diatomite was added, and the stirring was continued for 2 h, and then filtered, the filter cake was washed with deionized water and anhydrous ethanol for 4 times respectively, and vacuum dried at 70°C for 2 h to obtain an immobilized enzyme preparation.

[0050] S5: The calcareous sand was passed through a 3mm sieve, then rinsed under deionized water, and dried in an oven at 70°C for 2h to obtain pretreated calcareous sand; 450g of urea and 6L of deionized water were added to a reaction kettle, stirred at 25°C and 600r / min for 12min to form a urea solution, then 2kg of pretreated calcareous sand and 600g of immobilized enzyme preparation were added, and stirring was continued for 4h to obtain a tailings-microorganism composite injection mortar.

[0051] Comparative Example 1: On the basis of Example 3, the calcareous diatomite in step S2 was replaced by the diatomite prepared in step S1.

[0052] Comparative Example 2: On the basis of Example 3, the composite calcareous diatomite in step S4 was replaced by the calcareous diatomite prepared in step S1.

[0053] Comparative Example 3: On the basis of Example 3, the immobilized enzyme preparation in step S5 was replaced by the composite calcareous diatomite prepared in step S2.

[0054] Performance tests were performed on Examples 1-3 and Comparative Examples 1-3, and the tailings-microorganism composite injection mortar prepared in the examples and comparative examples was loaded into a test mold, and after molding, the sample was cured in an environment of 23°C and 60% relative humidity for 7 days to form a 40x40x160mm 3 sample, and the compressive strength was tested at a rate of 2500N / S; the maximum pressure at which water permeated was tested according to the process of the JGJ / T-2009 "Standard Test Methods for Basic Properties of Building Mortar" permeability test, wherein the curing time after demolding was 14 days.

[0055] Heavy metal content analysis test (test of manganese and copper elements): the tailings-microorganism composite injection mortar was crushed and sieved, 5g was taken in a test tube, 25ml of deionized water was added, and oscillation was performed for 5min, and after standing for 4 days, the upper clear liquid was taken. The heavy metal content in the upper clear liquid was tested by coupled plasma emission spectrometry (ICP-OES, lower limit of measurement: 0.001mg / L),

[0056] The results are shown in Table 1:

[0057] Table 1: Performance test data table of composite injection mortar

[0058] Item 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 Permeation resistance 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

[0059] As can be seen from Table 1, the compressive strength and permeability pressure of the tailings-microorganism composite injection mortar of Examples 1-3 are significantly better than those of the comparative examples, indicating that the tailings-microorganism composite injection mortar prepared by the present application has excellent compressive strength and permeability performance, and has a good removal effect on heavy metals.

[0060] The calcium-based diatomite in Comparative Example 1 is replaced by diatomite in step S1, and the microbial immobilization fails. The original diatomite is not activated by calcium ions, and the surface lacks calcium ion exchange sites, which cannot stably adsorb sodium alginate microcapsules through electrostatic action. The cross-linking of sodium alginate depends on calcium ions, and the original diatomite lacks calcium-based active sites, resulting in a decrease in microcapsule formation rate and an increase in microbial leakage rate.

[0061] In Comparative Example 2, the composite calcium-based diatomite is replaced by the calcium-based diatomite prepared in step S1, and the heterogeneous nucleation ability is lost. The calcium-based diatomite lacks iron MOF, which cannot provide lattice matching sites for calcium carbonate crystallization, resulting in a decrease in strength. The absence of iron-based MOF leads to a decrease in extracellular electron transfer efficiency, a decrease in urea hydrolysis rate, and a decrease in calcium carbonate deposition rate.

[0062] In Comparative Example 3, the immobilized enzyme preparation is replaced by the composite calcium-based diatomite prepared in S2, and the composite calcium-based diatomite is not coated with sodium alginate microcapsules. The microorganisms are destroyed by the shear force of the water flow during the mortar stirring and spraying process, and the loss rate increases. The ammonia gas produced by urea decomposition cannot be adsorbed by the microcapsules, the local pH rises, the urease activity is inhibited, and the calcium carbonate deposition is uneven.

[0063] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application.

Claims

1. A method for preparing a tailings-microorganism composite injection mortar, characterized by, It comprises the following steps: Step one: through the electrostatic effect of calcium chloride and activated diatomite, realize the chemical immobilization of calcium ions on the surface of diatomite, obtain calcium-based diatomite, and hydrothermally synthesize composite calcium-based diatomite with iron ions by taking the same as the carrier; Step two: through the cross-linking of sodium alginate and calcium ions, form a microcapsule structure with microbial inoculum as the core, load on the composite calcium-based diatomite to obtain an immobilized enzyme preparation; Step three: stir and mix urea solution, pretreated calcareous sand and immobilized enzyme preparation to obtain a tailings and microbial composite injection mortar; The specific preparation steps of the calcium-based diatomite are as follows: Put diatomite and sodium bicarbonate solution with a mass fraction of 10-20% into a reaction kettle, vacuum impregnate for 2-4h under the condition of 20-25℃ and 500-600r / min, then add calcium chloride solution with a mass fraction of 40-50%, continue to react for 1-2h, filter, wash the filter cake with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dry at 60-70℃ for 1-2h to obtain calcium-based diatomite; The specific preparation steps of the composite calcium-based diatomite are as follows: Put 2,5-dihydroxyterephthalic acid and N,N-dimethylformamide solution into a polytetrafluoroethylene lined autoclave, stir for 30-40min under the condition of 20-25℃ and 500-600r / min, then add ferric chloride, heat to 120-130℃, continue to react for 10-12h, then add calcium-based diatomite, continue to react for 10-12h, 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℃ for 1-2h to obtain composite calcium-based diatomite; The specific preparation steps of the immobilized enzyme preparation are as follows: Put sodium alginate and deionized water into a reaction kettle, stir for 10-12min under the condition of 20-25℃ and 500-600r / min, then add microbial inoculum, continue to stir for 30-40min to obtain a mixed solution; drop the mixed solution into calcium chloride solution with a mass fraction of 3-4%, then add composite calcium-based diatomite, continue to stir for 1-2h, filter, wash the filter cake with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dry at 60-70℃ for 1-2h to obtain immobilized enzyme preparation.

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

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

4. The method for preparing a composite jet mortar of tailings and microorganisms according to claim 1, characterized in that, The specific preparation steps of the microbial inoculum are as follows: The culture solution is prepared by using the formula ATCC 1376 NH4-YE recommended by the American Type Culture Collection, and then the culture solution is sterilized at 121-123 DEG C for 20-30 min, and then placed on the clean bench for ultraviolet sterilization and ventilation, and when the temperature of the culture solution is reduced to room temperature, the culture solution is taken in a container, and the Bacillus pasteurii is added into the culture solution by using a sterile pipette to obtain a bacterial solution, the volume ratio of the Bacillus pasteurii to the culture solution is 1:100, and the bacterial solution is placed in a constant temperature shaking incubator for culture, the temperature of the constant temperature shaking incubator is 28-32 DEG C, the shaking frequency is 200-320 r / min, and the culture time is 48-72 h, so that the microbial inoculant is obtained.

5. The method for preparing a composite jet mortar of tailings and microorganisms according to claim 1, characterized in that, The sodium alginate, deionized water and microbial inoculant are used in a ratio of 1-2 kg: 2-3 L: 40-50 g; the mixed solution, calcium chloride solution and composite calcium-based diatomite are used in a ratio of 800-900 mL: 1-2 L: 1-1.2 kg.

6. The method for preparing a composite jet mortar of tailings and microorganisms according to claim 1, characterized in that, The tailings and microbial composite sprayed mortar is prepared by the following steps: The urea and deionized water are added into a reaction kettle, and stirred at 20-25 DEG C and 500-600 r / min for 10-12 min to form a urea solution, and then the pretreated calcareous sand and immobilized enzyme preparation are added, and the stirring is continued for 3-4 h to obtain a tailings and microbial composite sprayed mortar. The urea, deionized water, pretreated calcareous sand and immobilized enzyme preparation are used in a ratio of 400-450 g: 5-6 L: 1-2 kg: 500-600 g.

7. The method for preparing a composite jet mortar of tailings and microorganisms according to claim 6, characterized in that, The pretreated calcareous sand is prepared by the following steps: The calcareous sand is passed through a 2-3 mm sieve, and then rinsed in deionized water, and dried in an oven at 60-70 DEG C for 1-2 h to obtain the pretreated calcareous sand.

8. A tailings and microorganism composite injection mortar, characterized by, The tailings and microbial composite sprayed mortar is prepared by the method of any one of claims 1-7.