Method for preparing MVTS-NaHCO3 composite powder explosion suppressant from vanadium-titanium waste residues and application of MVTS-NaHCO3 composite powder explosion suppressant

Abstract

The invention discloses a method for preparing an MVTS-NaHCO3 composite powder explosion suppressant from vanadium-titanium waste residues and application, and relates to the technical field of powder explosion suppressant compounding, and the method comprises the following specific steps: firstly pretreating and modifying the vanadium-titanium waste residues to obtain vanadium-titanium waste residues MVTS, and then preparing the vanadium-titanium waste residues MVTS powder into an MVTS suspension; adding a surfactant into the NaHCO3 solution, so as to obtain an active NaHCO3 solution; mixing and stirring the MVTS suspension and the active NaHCO3 solution, adding a solventing-out agent, and performing supersaturation precipitation on NaHCO3; uniformly loading the NaHCO3 crystals on the surface of the MVTS to form composite powder with a core-shell structure; and separating the composite powder, washing, drying and calcining to obtain the MVTS-NaHCO3 composite powder explosion suppressant. The method has the beneficial effects that after the vanadium-titanium waste residues are modified, the MVTS-NaHCO3 composite powder explosion suppressant with a relatively good composite effect can be prepared by utilizing a solventing-out-crystallization wet coating method, and the explosion suppressant realizes explosion suppression through a physical and chemical synergistic effect and has a remarkable explosion suppression effect on PNA dust.

Description

Technical Field

[0001] The present invention relates to the technical field of powder explosion suppressant compounding, and in particular to a method for preparing an MVTS-NaHCO3 composite powder explosion suppressant by utilizing vanadium-titanium waste slag and application thereof. Background Art

[0002] Vanadium-titanium slag (VTS), a major industrial solid waste generated during the ilmenite smelting process, produces over 10 million tons annually. Its main components are metal oxides such as TiO2, FeO, and Al2O3, and it exhibits excellent thermal stability and adsorption properties. However, the current resource utilization rate of VTS is less than 30%. Large-scale stockpiling not only occupies land resources but also poses environmental risks such as heavy metal pollution. Using VTS to prepare explosion suppression materials not only achieves efficient utilization of solid waste resources but also provides innovative solutions for dust explosion prevention and control, with significant environmental and economic benefits.

[0003] In the field of developing explosion suppressants from solid waste, most research focuses on the preparation of hybrid composite materials with synergistic effects through the combination of two or more materials. For example, Wang et al. used red mud and Ca(H2PO4)2 to prepare a core-shell Ca(HPO4)2 / RM composite explosion suppressant, which was successfully applied to suppress aluminum powder explosions. Wang et al. developed a high-efficiency powder explosion suppressant by combining shell powder with active powder, significantly improving the suppression effect of coal dust explosions. Yan et al. prepared a powder explosion suppressant by combining diatomaceous earth with NaHCO3, which demonstrated excellent performance in suppressing aluminum powder explosions. These studies not only provide new avenues for the resource utilization of solid waste but also lay an important foundation for innovation in dust explosion prevention and control technologies.

[0004] In recent years, composite powder explosion suppressants have become a research hotspot due to their synergistic effects. NaHCO3 is a commonly used chemical inhibitor, and its decomposition products CO2 and H2O can effectively dilute the oxygen concentration and capture free radicals. However, when used alone, it has defects such as poor dispersibility and short action time. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention discloses a method for preparing an MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag. Modified vanadium-titanium waste slag is used as a carrier, and NaHCO3 is loaded by a dissolution-crystallization wet coating method to prepare an MVTS-NaHCO3 composite powder explosion suppressant. The porous structure of the vanadium-titanium waste slag is utilized to enhance the dispersibility and thermal stability of NaHCO3, while exerting a synergistic explosion suppression effect of the two.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing an MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag, comprising the following steps:

[0008] Step 1: remove metallic iron impurities in the vanadium-titanium slag by magnetic separation or flotation, form a metal ion solution after acid dissolution, remove undissolved residue by filter pressing or centrifugation, then oxidize with hydrogen peroxide, and adjust the pH with ammonia water to obtain a hydroxide precipitate. Separate the precipitate by vacuum filtration or filter pressing to obtain the modified vanadium-titanium waste slag MVTS;

[0009] Step 2: using ultrasonic dispersion method to prepare MVTS suspension from the modified vanadium titanium waste slag MVTS powder;

[0010] Step 3, preparing a NaHCO3 solution, and adding a certain amount of surfactant to the NaHCO3 solution to obtain an active NaHCO3 solution;

[0011] Step 4: Mix the MVTS suspension of step 2 and the active NaHCO3 solution of step 3 in a certain mass ratio, stir, and then slowly add a solvent to supersaturate and precipitate NaHCO3; continue stirring to uniformly load the NaHCO3 crystals on the MVTS surface to form a composite powder with a core-shell structure; then separate the composite powder by vacuum filtration or filter press, wash it alternately with deionized water and ethanol several times, and dry and calcine the wet filter cake to obtain the MVTS-NaHCO3 composite powder explosion suppressant.

[0012] Furthermore, the specific process of step 1 is as follows:

[0013] (1.1) Grinding the vanadium-titanium slag to a particle size of ≤100 μm, and removing metallic iron impurities by magnetic separation or flotation to obtain vanadium-titanium slag powder;

[0014] (1.2) adding a 1-3 mol / L hydrochloric acid or sulfuric acid solution to the impurity-removed vanadium-titanium slag powder at a solid-liquid ratio of 1:2-1:5, stirring and reacting at 70° C. for 2 h to dissolve the metal oxide and obtain a metal ion solution;

[0015] (1.3) Remove the undissolved residue by filtration or centrifugation, collect the filtrate, and then add an appropriate amount of hydrogen peroxide to the filtrate to remove the Fe 2+ Oxidized to Fe 3+ ;

[0016] (1.4) Slowly add 2-4 mol / L ammonia solution under stirring, adjust the pH to 8, and control the temperature at 70°C to precipitate the metal ions as hydroxides;

[0017] (1.5) Use vacuum filtration or filter press to separate the hydroxide precipitate and wash it repeatedly with deionized water until the filtrate is neutral to remove residual Cl- or SO4 2- ;

[0018] (1.6) The wet filter cake was dried at 105°C to a constant weight to obtain the modified vanadium titanium waste slag MVTS.

[0019] Furthermore, in step 2, the modified vanadium-titanium waste slag MVTS is ground to a particle size of ≤50 μm, and the MVTS powder is dispersed in deionized water using an ultrasonic dispersion method to obtain an MVTS suspension with a concentration of 10-20 wt %, which is then set aside.

[0020] Furthermore, in step 3, a certain amount of analytically pure NaHCO3 with a purity of ≥99% was weighed and dissolved in deionized water to prepare a 0.5-1.0 mol / L NaHCO3 solution;

[0021] Sodium lauryl sulfate was selected as the surfactant, and the amount of sodium lauryl sulfate added to the active NaHCO3 solution was 0.2 wt%.

[0022] Furthermore, in step 3, the mass ratio of the MVTS suspension to the active NaHCO3 solution is 1:2-1:5, and magnetic stirring is performed at 30-50°C for 30 minutes to obtain a mixed solution;

[0023] The solvent is anhydrous ethanol, and the volume ratio of the solvent to the mixed solution is 1:2;

[0024] The drying conditions of the wet filter cake are: 60-80°C, 12h, and the calcination conditions are: 100-150°C, 1h.

[0025] Furthermore, the particle size of the prepared MVTS-NaHCO3 composite powder explosion suppressant is 20 to 80 μm.

[0026] The invention also discloses the application of the MVTS-NaHCO3 composite powder explosion suppressant prepared by the method in suppressing PNA dust explosion.

[0027] The beneficial effects of the present invention are that, compared with the prior art, it has the following characteristics:

[0028] (1) The feasibility of using vanadium-titanium waste slag to prepare industrial solid waste-based composite powder explosion suppressant. After modifying the vanadium-titanium waste slag, a MVTS-NaHCO3 composite powder explosion suppressant with good composite effect can be prepared using a dissolution-crystallization wet coating method.

[0029] (2) In the explosion suppression experiments in closed spaces and semi-open spaces of the present invention, by adding different proportions of MVTS-NaHCO3, MVTS and NaHCO3 composite powder explosion suppressants, it was found that the MVTS-NaHCO3 composite powder explosion suppressant had the most significant explosion suppression effect on PNA dust. In a closed space, more than 30% of the MVTS-NaHCO3 composite powder explosion suppressant can completely suppress the explosion of PNA dust, and as the amount of explosion suppressant added increases, the explosion pressure drop rate also increases. In a semi-open space, 40% of the MVTS-NaHCO3 composite powder explosion suppressant can reduce the maximum explosion pressure of PNA dust to 0.08MPa, with a drop rate of 82.6%. A 50% mass fraction of the MVTS-NaHCO3 mixture can completely suppress the explosion of PNA dust.

[0030] (3) The MVTS-NaHCO3 composite powder prepared by the present invention achieves explosion suppression through the synergistic effects of physical and chemical factors. The physical effect is primarily manifested in the endothermic decomposition of NaHCO3 and the enhanced dispersibility of the MVTS porous structure, while the chemical effect is primarily manifested in interrupting the combustion chain reaction by delaying the decomposition of NaHCO3 and generating alumina to quench free radicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the preparation process of MVTS-NaHCO3 composite powder explosion suppressant in an embodiment of the present invention;

[0032] Figure 2 This is the SEM of the MVTS-NaHCO3 composite powder explosion suppressant in the embodiment of the present invention;

[0033] Figure 3 This is a diagram showing the adsorption and desorption effects of nitrogen on the MVTS-NaHCO3 composite powder explosion suppressant in an embodiment of the present invention;

[0034] Figure 4 This is the application example of the present invention, which shows the suppression characteristics of the explosion suppressant on the PNA dust explosion pressure in a 20L enclosed space;

[0035] Figure 5 This is a maximum explosion pressure curve diagram of the explosion suppression process in an application example of the present invention. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0037] The present invention discloses a method for preparing MVTS-NaHCO3 composite powder explosion suppressant by utilizing vanadium-titanium waste slag. Figure 1 The specific steps are as follows:

[0038] 1. Process of preparing modified vanadium-titanium waste slag MVTS

[0039] The vanadium-titanium waste slag sample was taken from Pangang Vanadium Titanium Resources Co., Ltd., and the vanadium-titanium waste slag was subjected to XRF analysis. The results are shown in Table 1, which shows that the main components of the vanadium-titanium waste slag include: TiO2, FeO, Fe2O3, Al2O3, SiO2, CaO, MgO, V2O5, etc.

[0040] Table 1 XRF analysis of waste incineration slag

[0041]

[0042] First, the metal oxides in the vanadium-titanium slag are converted into metal hydroxides using an acid-base treatment method. This is because metal hydroxides and metal ions have certain explosion suppression activity. The method is as follows:

[0043] Pretreatment: Grind the vanadium-titanium slag (VTS) to a particle size of ≤100μm to increase the reactive surface area, and then use magnetic separation or flotation to remove impurities such as metallic iron in the waste slag to improve purity.

[0044] (2) Acid dissolution treatment: Add the pretreated VTS powder to a 1-3 mol / L hydrochloric acid (HCl) or sulfuric acid (H2SO4) solution with a solid-liquid ratio of 1:5, and stir at 70°C for 2 h to dissolve the metal oxides (such as FeO, Al2O3, TiO2) to form a metal ion solution. The reaction process is as follows:

[0045] FeO+2HCl→FeCl2+H2O (1)

[0046] Al2O3+6HCl→2AlCl3+3H2O (2)

[0047] TiO2+2H2SO4→Ti(SO4)2+2H2O (3)

[0048] (3) Filtration and impurity removal: Remove undissolved residues (such as SiO2) by filtration or centrifugation, and collect the filtrate; then add an appropriate amount of hydrogen peroxide (H2O2) to the filtrate to remove Fe 2+ Oxidized to Fe 3+ , which is convenient for subsequent sedimentation control.

[0049] (4) Alkali neutralization precipitation: Under stirring conditions, slowly add ammonia (NH3-H2O) solution with a concentration of 2-4 mol / L, adjust the pH to 8, and control the temperature at 70°C to precipitate the metal ions in the form of hydroxides. The reaction process is as follows:

[0050] Fe 3+ +3OH - →Fe(OH)3↓ (4)

[0051] Al 3+ +3OH - →Al(OH)3↓ (5)

[0052] Ti 4+ +4OH - →Ti(OH)4 (or dehydrated to form TiO(OH)2) (6)

[0053] (5) Filtration and washing: Use vacuum filtration or filter press to separate the hydroxide precipitate and wash it repeatedly with deionized water until the filtrate is neutral to remove residual Cl - or SO4 2- ;

[0054] (6) Drying: The wet filter cake is dried at 105° C. to a constant weight to obtain the modified vanadium-titanium waste slag MVTS.

[0055] 2. Preparation process of MVTS suspension

[0056] The modified vanadium-titanium waste slag MVTS after acid-base treatment is ground to a particle size of ≤50 μm to increase the specific surface area. The MVTS powder is dispersed in deionized water using ultrasonic dispersion to obtain an MVTS suspension with a concentration of 10-20 wt% for later use.

[0057] 3. Preparation process of active NaHCO3 solution

[0058] Weigh a certain amount of analytically pure NaHCO3 with a purity of ≥99%, dissolve it in deionized water to prepare a 0.5-1.0 mol / L NaHCO3 solution; and add a certain amount of sodium lauryl sulfate to the NaHCO3 solution, the addition amount of sodium lauryl sulfate is 0.2wt%, to obtain an active NaHCO3 solution.

[0059] 4. Dissolution-crystallization loading process

[0060] The MVTS suspension was mixed with the active NaHCO3 solution at a mass ratio of 1:3 and magnetically stirred at 30-50°C for 30 min to allow full contact between the carrier and the solute;

[0061] Slowly add anhydrous ethanol with a volume ratio of anhydrous ethanol to solution of 1:2 to induce supersaturated precipitation of NaHCO3; continue stirring for 1-2 hours to uniformly load the NaHCO3 crystals on the VTS surface to form a composite powder with a core-shell structure; then separate the composite powder by vacuum filtration or filter press, and wash it alternately with deionized water and ethanol for 3 times to remove residual impurities; place the wet filter cake in a 60-80℃ oven to dry for 12 hours, and calcine the dried powder at 100-150℃ for 1 hour to promote weak bonding between NaHCO3 and the hydroxyl groups on the surface of MVTS, thereby obtaining a VTS-NaHCO3 composite powder explosion suppressant.

[0062] The MVTS-NaHCO3 composite powder explosion suppressant prepared above was subjected to microscopic analysis. Figure 2 As shown, the particle size is around 20 μm. The MVTS-NaHCO3 composite powder explosion suppressant prepared by the dissolution-crystallization wet coating method (WCSC method) is more fully coated than MVTS alone, and the pores of the MVTS are completely filled with NaHCO3.

[0063] Table 2 Specific surface area and pore volume analysis of composite powder explosion suppressant

[0064]

[0065] As shown in Table 2, the specific surface area and pore volume of the MVTS-NaHCO3 composite powder explosion suppressant are smaller than those of VTS. This is because after the compounding process, NaHCO3 can be effectively compounded onto MVTS. Figure 3 As shown, the nitrogen adsorption-desorption isotherm of MVTS exhibits a type IV-H2(a) hysteresis loop according to the IUPAC classification, indicating that MVTS has relatively uniform pores. The MVTS-NaHCO3 composite powder explosion suppressant exhibits a type III isotherm, indicating that the composite powder explosion suppressant is a non-porous material.

[0066] Application Example 1

[0067] The MVTS-NaHCO3 composite powder explosion suppressant prepared above was used in the polyacrylonitrile (PAN) dust explosion suppression experiment process.

[0068] During the experiment, according to the national standard GB / T16425, a standard 20L spherical explosion system was used to conduct explosion suppression characteristic experiments. During the experiment, a 10kJ chemical igniter was first installed at the center of the ignition electrode in the 20L spherical tank, and then the spherical tank was closed. A certain mass of dust was placed in the dust bin, and the explosion chamber was evacuated to 0.06MPa, and the dispersion air pressure was set to 2.0MPa. When the solenoid valve between the dust storage container and the test chamber was automatically opened, the air and dust mixture was sprayed into the explosion chamber and ignited by the igniter after a delay of 60ms. The experiment selected the PNA dust concentration with the strongest explosion index (500g / m 3 ) as the benchmark concentration for explosion suppression experiments.

[0069] In the experiments, 10g of PNA was mixed with MVTS, MVTS-NaHCO₃, and NaHCO₃ in the proportions shown in Table 3, and tested according to the experimental parameters. The experiments were conducted in ascending order of the amount of explosion suppressant added, with each set of experiments repeated three times. In the study of the explosion characteristics of the 20L spherical explosion, the maximum values of the maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate ((dP / dt)max) were selected as the analysis basis.

[0070] Table 3 Ratio of mixed dust materials in explosion characteristics experiment

[0071]

[0072] A transparent pipe explosion propagation test system was used to conduct an in-depth analysis of the propagation characteristics of explosion flames. The system has a 0.15-meter-diameter pipe and consists of six sections, each 0.5 meters long, for a total length of 3 meters. It can be used to simulate dust explosions and explosion suppression processes in industrial environments. The system includes a powder spraying system, an ignition system, a data acquisition system, a high-speed camera, and a piping system. During the experiment, the target powder was first placed in the dust silo. The air supply was then turned on, and compressed air was introduced into the air tank until the rated spray pressure (1 MPa) was reached. The air supply was then stopped. Next, the ignition energy parameters (E = 20 J) and ignition delay time (t = 25 ms) were set. The experiment was initiated through the control system. After the solenoid valve opened, compressed air sprayed the dust from the dust silo into the pipe through the dispersion valve, evenly distributing it within the pipe space. After the set delay time, the ignition system triggered ignition, igniting the target powder.

[0073] During the experiment, PNA was mixed with MVTS, MVTS-NaHCO3, and NaHCO3, and the experiment was carried out according to the material proportions and experimental parameters shown in Table 4. During the experiment, the experiments were carried out in the order of increasing the amount of explosion suppressant added. Each experiment was carried out 3 times. In the flame propagation characteristics experimental study, the group of results with the longest flame length was taken for analysis.

[0074] Table 4 Ratio of mixed dust in the dust explosion propagation characteristics experiment

[0075]

[0076] In this experimental study, PNA dust was selected as the explosion suppression object, and MVTS, NaHCO3 and MVTS-NaHCO3 composite powders were selected as explosion suppressants.

[0077] During the experiment, the dust was poured into the grinding device in proportion and mixed using a planetary ball mill (TC-XQM4). The speed was set to 400r / min and the grinding was continued for 4 minutes. Subsequently, the ground dust was sieved according to the Taylor standard sieving method to prepare a mixed dust with a particle size of less than 75μm. The explosion pressure change curve was obtained through the experiment, as shown in the figure below. Figure 4 The experimental environment was controlled by the laboratory air conditioning system and set at a room temperature of 27°C, a relative humidity of 67%, and an atmospheric pressure of 99.1 kPa. The experimental results show that when the MVTS-NaHCO3 composite powder explosion suppressant is added at a concentration exceeding 30%, it can completely suppress the explosion of PNA dust. In contrast, the suppression effect of 30% MVTS and NaHCO3 on PNA dust explosion pressure is significantly weaker than that of 30% MVTS-NaHCO3 composite powder explosion suppressant. The maximum pressure drop rates are 53.2% for MVTS-NaHCO3 composite powder explosion suppressant, 50.6% for NaHCO3, and 47.8% for MVTS, respectively. At the same addition ratio, the suppression effect of the three explosion suppressants on PNA dust explosions is as follows: MVTS-NaHCO3 composite powder explosion suppressant > NaHCO3 > MVTS.

[0078] Using a transparent pipe explosion propagation system, PNA dust was mixed with MVTS-NaHCO3 composite powder explosion suppressant and MVTS and NaHCO3 composite powder explosion suppressant to conduct mixed dust explosion characteristic experiments. For the data measured by each pressure sensor, the maximum pressure value was taken as the pressure value of the pressure wave passing through the measuring point, and a discrete curve of the mixture dust explosion pressure change was drawn, as shown in Figure 2. Figure 5As shown in the figure, after the PNA dust ignites, it generates a large number of reaction products, which are released in a short period of time, building up pressure within the pipeline. As the pressure continues to build, a pressure wave forms. During the ignition phase, the pipeline pressure gradually rises, and the pressure value detected by pressure sensor 1 at 0.2 m is the maximum PNA dust explosion pressure of 0.46 MPa. As the explosion progresses, the amount of shale dust participating in the explosion decreases, and the amount of explosion products produced decreases. The pressure released within the pipeline gradually decreases. Simultaneously, the pressure wave is weakened by the resistance of the pipeline wall, and the pressure value measured by sensor 5 at 2.2 m drops to 0.13 MPa. Adding an explosion suppressant to the shale dust reduces the combustion reaction rate, reducing the amount of shale dust involved in the explosion, and reducing the amount of reactants produced by the explosion, thereby lowering the pressure within the pipeline. The data shows that 40% MVTS-NaHCO3 reduces the maximum explosion pressure of shale dust to 0.08 MPa, a maximum explosion pressure reduction rate of 82.6%. The maximum explosion pressure of the mixture decreased significantly after adding different mass fractions of MVTS-NaHCO3, and the 50% mass fraction MVTS-NaHCO3 mixture could completely suppress PNA dust.

[0079] To investigate the characteristics of the reaction products generated during the explosion, this study systematically collected and analyzed the products after a 20L spherical explosion experiment. The explosion products primarily consisted of gaseous and solid products. Gases were collected using a dedicated gas sampling device within 30 seconds of the explosion, and qualitative and quantitative analysis of the gas composition was performed using a Shimadzu gas chromatograph-mass spectrometer (GCMS-QP2010 Ultra, Japan). Solid products were collected directly after the experiment and analyzed using an EDX 4500H XRF analyzer (Jiangsu Tianrui Instruments, China). The compositional analysis results of the main explosion products are shown in Table 5. GCMS analysis of the gaseous products revealed that the primary gaseous products of the PNA dust explosion and its mixed dust explosion with an explosion suppressant were CO₂, NO₂, CO, and SO₂. The addition of a 20% MVTS-NaHCO₃ composite powder explosion suppressant increased the CO₂ content by 5.2% and the CO content by 2.2% in the mixed dust explosion gaseous products. This phenomenon is attributed to the dual effect of the explosion suppressant: it not only reduces the total amount of PNA dust participating in the reaction, but also reduces CO2 production and increases CO production due to the suppression of the combustion reaction.

[0080]

[0081] At the same time, NaHCO3 in the explosion suppressant generates CO2 in the explosion environment, so the CO2 content in the explosion-generated substances does not increase much.

[0082]

[0083] XRF analysis of solid products showed that the main substances of the mixed dust before explosion with 20% MVTS-NaHCO3 composite powder explosion suppressant added were SiO2, Fe2O3, Al2O3, CaO, etc. After the explosion of the mixed dust, the content of Fe2O3 and Al2O3 increased slightly. This was because the thermal decomposition of metal hydroxides such as Al(OH)3 and Fe(OH)3 in the explosion suppressant absorbed heat to form metal oxides such as Al2O3 and Fe2O3, resulting in an increase in the content of Fe2O3 and Al2O3.

[0084] Table 5 Composition analysis results of main explosion products

[0085]

[0086] Microscopic analysis clearly demonstrates how the composite powder achieves explosion suppression through a synergistic combination of physical and chemical interactions. Physically, the decomposition of NaHCO₃ is an endothermic reaction, absorbing approximately 100 kJ / mol of heat. This process not only releases CO₂ and H₂O, but also effectively dilutes the oxygen concentration, reducing the potential for combustion. Furthermore, the porous structure of MVTS further enhances the dispersion of the composite powder, making its distribution more uniform throughout the material, thereby improving the explosion suppression effect. Chemically, bonding occurs between the hydroxyl groups on the MVTS surface and the NaHCO₃, which helps to slow the decomposition process. Simultaneously, metal hydroxides, such as aluminum hydroxide (Al(OH)₃), produce aluminum oxide (Al₂O₃) during thermal decomposition. Aluminum oxide adsorbs and quenches free radicals, such as hydroxyl radicals (-OH) and hydrogen radicals (-H), which are key players in chain reactions. By inhibiting the generation and propagation of these free radicals, the composite powder can effectively interrupt the chain reaction in the combustion process, thereby achieving the purpose of suppressing combustion and explosion.

[0087] Currently, there are no reports on the effects of vanadium-titanium waste slag-based composite explosion suppressants on the explosion characteristics of PAN dust. This study, using a 20L spherical explosion device and a transparent pipe explosion propagation test system, systematically investigates the effects of varying mass fractions of MVTS-NaHCO composite powder on the explosion characteristics of PAN dust, revealing its explosion suppression mechanism at the microscopic level. The results not only provide new avenues for the resource utilization of vanadium-titanium waste slag, but also offer a theoretical basis and practical reference for optimizing industrial dust explosion prevention and control technologies.

[0088] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for preparing MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag, characterized in that: The specific steps are as follows: Step 1: remove metallic iron impurities in the vanadium-titanium slag by magnetic separation or flotation, form a metal ion solution after acid dissolution, remove undissolved residue by filter pressing or centrifugation, then oxidize with hydrogen peroxide, and adjust the pH with ammonia water to obtain a hydroxide precipitate. Separate the precipitate by vacuum filtration or filter pressing to obtain the modified vanadium-titanium waste slag MVTS; Step 2: using ultrasonic dispersion method to prepare MVTS suspension from the modified vanadium titanium waste slag MVTS powder; Step 3, preparing a NaHCO3 solution, and adding a certain amount of surfactant to the NaHCO3 solution to obtain an active NaHCO3 solution; Step 4: Mix the MVTS suspension of step 2 and the active NaHCO3 solution of step 3 in a certain mass ratio, stir, and then slowly add a solvent to supersaturate and precipitate NaHCO3; continue stirring to uniformly load the NaHCO3 crystals on the MVTS surface to form a composite powder with a core-shell structure; then separate the composite powder by vacuum filtration or filter press, wash it alternately with deionized water and ethanol several times, and dry and calcine the wet filter cake to obtain the MVTS-NaHCO3 composite powder explosion suppressant.

2. The method for preparing an MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag according to claim 1, characterized in that: Step 1 Specific process: (1.1) Grinding the vanadium-titanium slag to a particle size of ≤100 μm, and removing metallic iron impurities by magnetic separation or flotation to obtain vanadium-titanium slag powder; (1.2) adding a 1-3 mol / L hydrochloric acid or sulfuric acid solution to the impurity-removed vanadium-titanium slag powder at a solid-liquid ratio of 1:2-1:5, stirring and reacting at 70° C. for 2 h to dissolve the metal oxide and obtain a metal ion solution; (1.3) Remove the undissolved residue by filtration or centrifugation, collect the filtrate, and then add an appropriate amount of hydrogen peroxide to the filtrate to remove the Fe 2+ Oxidized to Fe 3+ ; (1.4) Slowly add 2-4 mol / L ammonia solution under stirring, adjust the pH to 8, and control the temperature at 70°C to precipitate the metal ions as hydroxides; (1.5) Use vacuum filtration or filter press to separate the hydroxide precipitate and wash it repeatedly with deionized water until the filtrate is neutral to remove residual Cl - or SO4 2- ; (1.6) The wet filter cake was dried at 105°C to a constant weight to obtain the modified vanadium titanium waste slag MVTS.

3. The method for preparing MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag according to claim 2, characterized in that: In step 2, the modified vanadium-titanium waste slag MVTS is ground to a particle size of ≤50 μm, and the MVTS powder is dispersed in deionized water using an ultrasonic dispersion method to obtain an MVTS suspension with a concentration of 10-20 wt %, which is then used for standby use.

4. The method for preparing an MVTS-NaHCO composite powder explosion suppressant using vanadium-titanium waste slag according to claim 3, characterized in that: In step 3, a certain amount of analytically pure NaHCO3 with a purity of ≥99% was weighed and dissolved in deionized water to prepare a 0.5-1.0 mol / L NaHCO3 solution; Sodium lauryl sulfate was selected as the surfactant, and the amount of sodium lauryl sulfate added to the active NaHCO3 solution was 0.2 wt%.

5. The method for preparing MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag according to claim 4, characterized in that: In step 3, the mass ratio of the MVTS suspension to the active NaHCO3 solution is 1:2-1:5, and magnetic stirring is carried out at 30-50°C for 30 minutes to obtain a mixed solution; The solvent is anhydrous ethanol, and the volume ratio of the solvent to the mixed solution is 1:2; The drying conditions of the wet filter cake are: 60-80°C, 12h, and the calcination conditions are: 100-150°C, 1h.

6. The method for preparing an MVTS-NaHCO3 composite powder explosion suppressant using vanadium-titanium waste slag according to claim 5, characterized in that: The particle size of the prepared MVTS-NaHCO3 composite powder explosion suppressant is 20-80 μm.

7. Use of the MVTS-NaHCO3 composite powder explosion suppressant prepared by the method described in any one of claims 1 to 6 in suppressing PNA dust explosion.

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