Microbial in-situ long-acting oxygen scavenger based on controllable sulfur cycle and preparation method and application thereof

Abstract

This invention discloses a microbial in-situ long-acting oxygen desiccant based on a controlled sulfur cycle, its preparation method, and its application. The method first prepares zeolite-phase porous inorganic particles using molten NaOH and blast furnace slag-fly ash powder, and then modifies them with cobalt oxide to obtain a nano-cobalt oxide-zeolite phase porous structure. Next, a highly selective oxygen adsorption porous structure is prepared by grafting short-chain alkyl sulfonate onto a porous medium. Finally, sulfur-reducing bacteria are loaded onto the highly selective oxygen adsorption porous particles using a silane coupling agent to obtain a microbial in-situ oxygen desiccant based on a controlled sulfur cycle in goaf. The raw materials used in this invention are widely available and inexpensive. The microbial controlled sulfur cycle in-situ long-acting oxygen desiccant method for preventing coal spontaneous combustion has advantages such as a wide effective concentration range, rapid oxygen consumption rate, and long-lasting effect. While preventing coal spontaneous combustion in goaf areas of coal mines, it can also suppress heavy metal pollution during coal mining, showing great potential in the fields of coal goaf prevention and green mining.

Description

Technical Field

[0001] This invention relates to the field of underground fire prevention and extinguishing technology in coal mines, specifically to a microbial in-situ long-acting oxygen-scavenging agent based on a controllable sulfur cycle, its preparation method, and its application. Background Technology

[0002] Coal mine fires are one of the major disasters encountered during underground mining. With increasing mining depth, spontaneous combustion accidents caused by excessively high oxygen concentrations due to air leakage occur frequently in underground mines. This not only seriously affects normal mining production but also threatens the lives of underground workers. Coal-oxygen barrier fire prevention and extinguishing technology is an important means of suppressing spontaneous combustion disasters in underground coal mines. It reduces the oxygen concentration to below the coal-oxygen combustion limit or alters the physical and chemical properties of coal, thereby reducing the tendency for spontaneous combustion and achieving the effect of fire prevention and extinguishing.

[0003] Currently, coal mines primarily employ methods such as nitrogen inerting and spraying inhibitors for coal-oxygen barrier fire prevention and extinguishing. Nitrogen injection involves directly injecting nitrogen into the underground goaf to replace the oxygen surrounding the coal, creating an inert environment that effectively prevents spontaneous combustion. Spraying inhibitors reduces the oxidative activity of coal by enhancing its thermal stability and moisture absorption / heat dissipation capacity or by catalytically decomposing intermediate products of coal oxidation, thereby inhibiting the oxidation reaction and reducing the tendency for spontaneous combustion. However, these methods also have limitations in practical applications. For example, after nitrogen inerting, the gas can easily escape through ventilation channels due to diffusion effects, causing the oxygen concentration in the goaf to rise again. Furthermore, the inhibitory effect of the coal spontaneous combustion inhibitor decreases over time, leading to the re-ignition of residual coal in the goaf, making long-term inhibition difficult. Therefore, there is an urgent need to develop a long-lasting and environmentally friendly coal-oxygen barrier fire prevention and extinguishing technology to solve these problems and achieve safe application of oxygen elimination for underground fire prevention and extinguishing. Summary of the Invention

[0004] The purpose of this invention is to provide a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle, its preparation method, and its application. The preparation method is simple and convenient, and the material cost is low. The prepared microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle can continuously reduce oxygen in underground coal mines, thereby achieving long-term prevention and control of coal spontaneous combustion disasters.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a method for preparing a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle, the preparation method comprising the following steps:

[0006] S1: NaOH is mixed with blast furnace slag-fly ash powder, calcined and melted at high temperature, then heated by ultrasonic water bath, vacuum dried and acid washed, and finally cleaned and dried to obtain zeolite phase porous inorganic particles.

[0007] S2: The zeolite-phase porous inorganic particles prepared in step S1 are placed in a cobalt chloride ethanol solution, and 3% by mass of 3-aminopropyltriethoxysilane is added to the cobalt chloride ethanol solution. The precursor is stirred to fully disperse the precursor. The temperature is controlled at 75℃~85℃ during the stirring process. Then, the mixture is calcined to obtain zeolite-phase porous inorganic particles modified with nano-cobalt oxide.

[0008] S3: The zeolite-phase porous inorganic particles modified with nano-cobalt oxide obtained in step S2 are immersed in a short-chain alkyl sulfonate sodium ethanol solution, loaded into a reaction vessel, and 5‰ of the mass of the short-chain alkyl sulfonate sodium ethanol solution of phenyltriethoxysilane is added. The vessel is then placed in an oven and heated to carry out a hydrothermal reaction. After the reaction is completed, the particles are cooled, washed, and dried. Finally, after grinding, the particles are passed through a 5-20 mesh sieve to obtain zeolite-phase porous inorganic microparticles modified with nano-cobalt oxide and short-chain alkyl sulfonate sodium.

[0009] S4: Polylysine and calcium chloride were added sequentially to the sulfur-reducing bacteria solution with an OD600 of about 0.8 to 1.2 in the late stage of exponential growth. The bacteria were stirred at room temperature to make the surface of the sulfur-reducing bacteria positively charged. The sulfur-reducing bacteria after positively charged cross-linking treatment were obtained by centrifugation and deionized water was added to prepare a positively charged sulfur-reducing bacteria solution.

[0010] S5: Immerse the zeolite-phase porous inorganic particles modified with nano-cobalt oxide and short-chain alkyl sulfonate obtained in step S3 into the positively charged sulfur-reducing bacteria solution prepared in step S4. After static adsorption, wash and dry to obtain a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle.

[0011] Preferably, in step S1, the calcination melting temperature is 800℃, the calcination time is 2h; the ultrasonic water bath temperature is 45℃, the heating time is 30min; the vacuum drying time is 4h; the acid washing is performed using a mixed acid composed of 1% acetic acid and 0.5% hydrochloric acid; the drying temperature is 70℃, and the drying time is 12h.

[0012] Preferably, in step S2, the mass ratio of the zeolite-phase porous inorganic particles to cobalt chloride is (5-20):1; the mixture is stirred at 100 rpm for 6 hours; the calcination temperature is 400℃ and the calcination time is 5 hours; the concentration of the cobalt chloride ethanol solution is 15-60 mg / mL.

[0013] Preferably, in step S3, the mass ratio between the zeolite-phase porous inorganic particles modified with nano-cobalt oxide and the short-chain alkyl sulfonate is (7-150):1; the hydrothermal reaction temperature is 150℃, the hydrothermal reaction time is 2h; and the concentration of the short-chain alkyl sulfonate ethanol solution is 6.7~11.1mg / mL.

[0014] Preferably, in step S4, the sulfur-reducing bacteria solution is a mixed bacterial solution, including at least two of the following: propionic acid desulfurizing bacteria, polyphagous desulfurizing cocci, rumen desulfurizing enterobacteria, desulfurizing bacilli, desulfurizing vibrio, and common heat desulfurizing bacilli.

[0015] Preferably, in step S5, the mass ratio of calcium chloride to polylysine is (1-4):1; and the mixture is stirred at 150 rpm for 30 min for crosslinking.

[0016] To achieve the above objectives, the present invention also provides a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle prepared by the above preparation method.

[0017] To achieve the above objectives, the present invention also provides the application of the microbial in-situ long-lasting oxygen scavenger based on the controllable sulfur cycle prepared by the above preparation method in the preparation of long-lasting oxygen scavenging and inhibition materials for fire prevention and extinguishing in coal mines. The specific application process is as follows: the microbial in-situ long-lasting oxygen scavenger is added to nitrogen foam at a ratio of 5% of the total mass to prepare microbial in-situ long-lasting oxygen scavenging nitrogen foam material.

[0018] The repair mechanism of this invention: The microbial in-situ long-lasting oxygen desiccant based on a controllable sulfur cycle prepared in this invention is transported to the target location through a water-rich carrier material. The free oxygen in the target area is enriched by zeolite-phase porous inorganic particles. The loaded short-chain alkyl sulfonate reacts with oxygen under the catalysis of nano-cobalt oxide to initially reduce the oxygen concentration. At the same time, the generated sulfate ions are reduced to hydrogen sulfide under the action of composite sulfur-reducing bacteria and participate in the oxidation reaction again, so as to continuously reduce oxygen in the coal mine and achieve long-lasting oxygen desiccant in the target area.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention utilizes the multivalent redox reaction of sulfur, the oxidation reaction of short-chain alkyl sulfonate catalyzed by cobalt oxide and the anaerobic metabolism of sulfur-reducing bacteria to reduce sulfate ions, to achieve long-term prevention and control of spontaneous combustion of coal in underground coal mines based on controlled sulfur cycle and oxygen reduction. This solves the problem that the prevention and control methods such as spraying inhibitors and nitrogen injection are short-term and easily lead to the re-ignition of residual coal.

[0021] 2. This invention reduces oxygen in the goaf of coal mines through a synergistic and controllable sulfur cycle process involving physical adsorption, catalytic oxidation, and bacterial reduction. The high-concentration oxygen reduction has a good coal-oxygen barrier effect on coal types with different spontaneous combustion tendencies, avoiding the problem of poor coal type applicability and easy secondary pollution caused by traditional inhibitors.

[0022] 3. The microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle prepared in this invention has a simple and convenient operation process for preventing spontaneous combustion of coal in underground coal mines, and the material cost is low; it has strong oxygen consumption and sulfur cycle stability and is suitable for the complex and harsh environment of underground coal mine goaf. Attached Figure Description

[0023] Figure 1 Images of the Zeta potential on the surface of sulfur-reducing bacteria after positive electrocrosslinking treatment with different concentrations of calcium chloride in Examples 1-6;

[0024] Figure 2 The graph shows the oxygen concentration change over time for testing the oxygen reduction and deoxygenation effect of the microbial in-situ long-acting oxygen scavengers prepared in Examples 7-9. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] A microbial in-situ long-acting oxygen scavenger based on a controlled sulfur cycle includes the following steps:

[0028] S1: Mix 10g NaOH with 12g blast furnace slag-fly ash powder and calcine at 800℃ for 2h. Then heat at 45℃ in an ultrasonic water bath for 30min and vacuum dry for 4h. Finally, acid wash with a mixture of 1% acetic acid and 0.5% hydrochloric acid. After washing and drying at 70℃ for 12h, zeolite-phase porous inorganic particles are obtained.

[0029] S2: 10g of zeolite-phase porous inorganic particles were placed in 100ml of cobalt chloride ethanol solution with a concentration of 15mg / mL. 3% of 3-aminopropyltriethoxysilane by mass of cobalt chloride ethanol solution was added as a stabilizer. The mixture was stirred at 100rpm for 6h to ensure that the precursor was fully dispersed. During the stirring process, the temperature was kept at about 80℃. Then, the mixture was calcined at 400℃ for 5h to obtain zeolite-phase porous inorganic particles modified with nano-cobalt oxide.

[0030] S3: Immerse 10g of the zeolite-phase porous inorganic particles modified with nano-cobalt oxide obtained in step S2 into a reaction vessel containing 100ml of a 6.7mg / mL solution of short-chain alkyl sulfonate in ethanol. Add 5‰ of the mass of the short-chain alkyl sulfonate in ethanol solution of ethanol. Place the vessel in an oven and heat to 150℃ for hydrothermal reaction for 8h. After the reaction is completed, cool, wash, and dry the particles. Finally, grind the particles and pass them through a 5-20 mesh sieve to obtain zeolite-phase porous inorganic microparticles modified with nano-cobalt oxide and short-chain alkyl sulfonate.

[0031] S4: Add 0.625g of polylysine and 2.5g of calcium chloride to 1000ml of sulfur-reducing bacteria solution with OD600 of 0.8-1.2 in the late stage of exponential growth. Stir at 150rpm for 30min at room temperature to make the surface of sulfur-reducing bacteria positively charged. Separate the sulfur-reducing bacteria after positively charged cross-linking treatment by centrifugation. Add deionized water to prepare positively charged sulfur-reducing bacteria solution.

[0032] S5: Immerse 10g of the zeolite-phase porous inorganic particles modified with nano-cobalt oxide and short-chain alkyl sulfonate obtained in step S3 into the positively charged sulfur-reducing bacteria solution prepared in step S4. After standing for adsorption for 24 hours, wash and dry to obtain a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle.

[0033] Example 2

[0034] The preparation method of this embodiment is the same as that of embodiment 1, except that the mass of polylysine and calcium chloride in step S4 of this embodiment is 0.5g and 2g, respectively.

[0035] Example 3

[0036] The preparation method of this embodiment is the same as that of embodiment 1, except that the mass of polylysine and calcium chloride in step S4 of this embodiment is 0.375g and 1.5g, respectively.

[0037] Example 4

[0038] The preparation method of this embodiment is the same as that of embodiment 1, except that the mass of polylysine and calcium chloride in step S4 of this embodiment is 0.25g and 1g, respectively.

[0039] Example 5

[0040] The preparation method of this embodiment is the same as that of embodiment 1, except that the mass of polylysine and calcium chloride in step S4 of this embodiment is 0.125g and 0.5g, respectively.

[0041] Comparative Example

[0042] The preparation method of this comparative example is the same as that of Example 1, except that polylysine and calcium chloride were not added in step S4 of this example.

[0043] Example 6

[0044] The preparation method of this embodiment is the same as that of embodiment 1, except that in step S4 of this embodiment, "0.2g of polylysine and 0.8g of calcium chloride are added sequentially".

[0045] 10L of nitrogen gas was introduced into 500ml of foam liquid through a vertical blower to prepare nitrogen foam for preventing spontaneous combustion of coal in coal mines. The microbial in-situ long-acting oxygen scavenger based on the controllable sulfur cycle prepared in this embodiment was added to the nitrogen foam at a ratio of 5% of the total mass to prepare microbial in-situ long-acting oxygen scavenging nitrogen foam material.

[0046] Example 7

[0047] The preparation method in this embodiment is the same as in embodiment 6, except that the concentrations of the cobalt chloride ethanol solution and the short-chain alkyl sulfonate sodium ethanol solution in steps S2 and S3 in this embodiment are 30 mg / mL and 8.3 mg / mL, respectively.

[0048] 10L of nitrogen gas was introduced into 500ml of foam liquid through a vertical blower to prepare nitrogen foam for preventing spontaneous combustion of coal in coal mines. The microbial in-situ long-acting oxygen scavenger based on the controllable sulfur cycle prepared in this embodiment was added to the nitrogen foam at a ratio of 5% of the total mass to prepare microbial in-situ long-acting oxygen scavenging nitrogen foam material.

[0049] Example 8

[0050] The preparation method of this embodiment is the same as that of embodiment 6, except that the concentrations of the cobalt chloride ethanol solution and the short-chain alkyl sulfonate sodium ethanol solution in steps S2 and S3 are 60 mg / mL and 11.1 mg / mL, respectively.

[0051] 10L of nitrogen gas was introduced into 500ml of foam liquid through a vertical blower to prepare nitrogen foam for preventing spontaneous combustion of coal in coal mines. The microbial in-situ long-acting oxygen scavenger based on the controllable sulfur cycle prepared in this embodiment was added to the nitrogen foam at a ratio of 5% of the total mass to prepare microbial in-situ long-acting oxygen scavenging nitrogen foam material.

[0052] Examples 6-8 use an air leakage and oxygen consumption simulation test device to verify the oxygen reduction effect of a microbial in-situ long-acting oxygen scavenger using nitrogen foam as a carrier. The device mainly consists of a miniature airflow pump, an oxygen concentration sensor, a pressure gauge, and a sealed tank with a diameter of 300 mm and a height of 400 mm. A 150 mm layer of engineering stones is pre-pile inside the tank. Gas is pumped into the tank using the miniature airflow pump. If the pressure gauge reading at the top of the device matches the pressure of the airflow pump pressure valve, it indicates good airtightness, and testing can begin. During testing, nitrogen foam mixed with the microbial in-situ long-acting oxygen scavenger is injected into the pipe, completely covering the engineering stone pile. Injection is then stopped. A 14% concentration oxygen-nitrogen mixture is continuously injected into the tank using the miniature airflow pump. After the oxygen concentration sensor reading stabilizes, the initial oxygen concentration C0 is recorded. Oxygen concentration data Ct is recorded after 1, 3, 5, 7, and 9 days, and the oxygen concentration change rate is calculated using the following formula:

[0053] η=(C0-C t ) / C0×100%

[0054] Where η is the oxygen concentration reduction rate, %; C0 is the initial oxygen concentration, %; C t The oxygen concentration after time t, in percentages.

[0055] Images of the Zeta potentials on the surface of sulfur-reducing bacteria after positively cross-linking treatment with different concentrations of CaCl2 in step S4 of the microbial in-situ long-acting oxygen scavengers prepared in Examples 1-5 and the comparative examples are shown below. Figure 1 As shown, with increasing calcium chloride concentration, the zeta potential on the surface of sulfur-reducing bacteria becomes positive and slowly increases, which helps sulfur-reducing bacteria to better attach to the surface of negatively charged short-chain alkyl sulfonate modified zeolite-phase porous inorganic particles through electrostatic adsorption.

[0056] The oxygen consumption effect of the microbial in-situ long-lasting oxygen-removing nitrogen foam materials prepared in Examples 6-8 is as follows: Figure 2 As shown, with the increase in the concentration of cobalt chloride ethanol solution and short-chain alkyl sulfonate sodium ethanol solution, the decrease in the oxygen consumption rate of the microbial in-situ long-acting oxygen-reducing nitrogen foam material gradually decreased. The oxygen concentration curve corresponding to Example 8 shows that the overall oxygen consumption rate of the microbial in-situ long-acting oxygen-reducing agent prepared by this material composition hardly decreased over time within 9 days. This is because the increased loading of nano-cobalt oxide and short-chain alkyl sulfonate sodium leads to a lower oxygen concentration, which is conducive to the increased activity of sulfur-reducing bacteria, resulting in increased sulfate reduction and maintaining the continuous oxygen consumption capacity of the controllable sulfur cycle. This indicates that the microbial in-situ long-acting oxygen-reducing agent based on the controllable sulfur cycle can effectively reduce the oxygen concentration in the target area of ​​the downstream coal mine, effectively preventing coal spontaneous combustion disasters.

Claims

1. A method for preparing a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle, characterized in that, Includes the following steps: S1: NaOH and blast furnace slag-fly ash powder are mixed evenly, calcined and melted at high temperature, then heated by ultrasonic water bath, vacuum dried, acid washed, and finally cleaned and dried to obtain zeolite-phase porous inorganic particles; the calcination melting temperature is 800℃, the calcination time is 2h; the ultrasonic water bath temperature is 45℃, the heating time is 30min; vacuum drying is 4h; acid washing is performed using a mixed acid composed of 1% acetic acid and 0.5% hydrochloric acid; the drying temperature is 70℃, the drying time is 12h; S2: The zeolite-phase porous inorganic particles prepared in step S1 were placed in a cobalt chloride ethanol solution, and 3% (by mass) of 3-aminopropyltriethoxysilane was added to the cobalt chloride ethanol solution. The mixture was stirred to fully disperse the precursor. The temperature was controlled at 75℃~85℃ during the stirring process, and then calcined to obtain zeolite-phase porous inorganic particles modified with nano-cobalt oxide. The mass ratio between the zeolite-phase porous inorganic particles and cobalt chloride was (5-20):

1. The mixture was stirred at 100 rpm for 6 hours. The calcination temperature was 400℃ and the calcination time was 5 hours. The concentration of cobalt chloride ethanol solution is 15~60 mg / mL; S3: The zeolite-phase porous inorganic particles modified with nano-cobalt oxide obtained in step S2 were immersed in a short-chain alkyl sulfonate sodium ethanol solution, loaded into a reaction vessel, and 5‰ of the mass of the short-chain alkyl sulfonate sodium ethanol solution of phenyltriethoxysilane was added. The vessel was then placed in an oven and heated for a hydrothermal reaction. After the reaction was completed, the particles were cooled, washed, and dried. Finally, after grinding, the particles were passed through a 5-20 mesh sieve to obtain zeolite-phase porous inorganic microparticles modified with nano-cobalt oxide and short-chain alkyl sulfonate sodium. The mass ratio between the zeolite-phase porous inorganic particles modified with nano-cobalt oxide and short-chain alkyl sulfonate sodium was (7-150):

1. The hydrothermal reaction temperature was 150℃, and the hydrothermal reaction time was 2h. The concentration of sodium short-chain alkyl sulfonate in ethanol solution is 6.7~11.1 mg / mL; S4: Polylysine and calcium chloride were added sequentially to the sulfur-reducing bacteria solution in the late stage of exponential growth with an OD600 of about 0.8~1.

2. The solution was stirred at room temperature to crosslink the sulfur-reducing bacteria, making the surface of the sulfur-reducing bacteria positively charged. The positively charged crosslinked sulfur-reducing bacteria were separated by centrifugation and deionized water was added to prepare a positively charged sulfur-reducing bacteria solution. The mass ratio of calcium chloride to polylysine was (1-4):

1. The solution was stirred at 150 rpm for 30 min for crosslinking. S5: Immerse the zeolite-phase porous inorganic particles modified with nano-cobalt oxide and short-chain alkyl sulfonate obtained in step S3 into the positively charged sulfur-reducing bacteria solution prepared in step S4. After static adsorption, wash and dry to obtain a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle.

2. The method for preparing a microbial in-situ long-acting oxygen scavenger based on a controllable sulfur cycle according to claim 1, characterized in that, In step S4, the sulfur-reducing bacteria solution is a mixed bacterial solution, including at least two of the following: propionic acid desulfurizing bacteria, polyphagous desulfurizing cocci, rumen desulfurizing enterobacteria, desulfurizing bacilli, desulfurizing vibrio, and common heat desulfurizing bacilli.

3. A microbial in-situ long-acting oxygen scavenger based on a controlled sulfur cycle, prepared by the preparation method described in claim 1 or 2.

4. The application of the microbial in-situ long-lasting oxygen scavenger based on controlled sulfur cycle as described in claim 3 in the preparation of long-lasting oxygen scavenging and flame retardant materials for fire prevention and extinguishing in coal mines, the specific application process is as follows: the microbial in-situ long-lasting oxygen scavenger is added to nitrogen foam at a ratio of 5% of the total mass to prepare microbial in-situ long-lasting oxygen scavenging nitrogen foam material.

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