Dust Suppression Research Articles

Molecular mechanism study on the effect of nonionic surfactants with different degrees of ethoxylation on the wettability of anthracite

A serious risk to the production safety of coal mines is coal dust. The wettability of coal may be successfully changed by adding surfactants to water. However, the creation of very effective dust suppressants is constrained by the lack of knowledge about the microscopic interaction mechanism between coal dust and surfactants. In this investigation, we explained macroscopic experimental phenomena from a molecular perspective. The lauryl polyoxyethylene ethers (C12 (EO)n, n = 7,15,23) were selected. The macromolecular model of anthracite with 55 different components was constructed. Surface tension experiments and hydrophilic lipophilic balance (HLB) calculations showed that the ability of surface hydrophilicization followed the order of C12 (EO)7<C12 (EO)15<C12 (EO)23. Contact angle experiment, XPS and FTIR experiments proved that after the surfactants were adsorbed on the surface of anthracite, the content of carbon element decreased and the content of oxygen element increased, indicating the enhanced surface hydrophilicity. The simulation results showed that with the degree of ethoxylation increases, the adsorption strength of surfactants becomes stronger, and the hydrophilic head group of surfactant on anthracite surface is more uniformly distributed. The greater the degree of ethoxylation, the more powerfully the modified coal surface can bind to water molecules.

Study on dust pollution law and ventilation optimization of roadway excavation and shotcrete simultaneous operation

The simultaneous operation of heading machine and shotcrete machine often occurs in the process of roadway development. Many dust sources, such as cutting dust and shotcrete dust, increase the complexity of roadway dust pollution. In order to find out the law of dust migration in tunneling and shotcrete operation at the same time, and put forward effective dust control optimization measures, this paper takes a mine roadway as an example, based on Fluent numerical simulation software, the dust migration law is analyzed when the roadway driving operation and the shotcrete operation are carried out separately and when the two operations are carried out simultaneously. Moreover, the orthogonal experiment is used to optimize the ventilation parameters of the working face. Results show that the dust concentration in the roadway decreases gradually from high to low when the single shotcrete operation is on the air inlet side. On the return air side, the dust concentration in the roadway increases first and then decreases. In the single tunneling process, the dust concentration on the return air side is significantly higher than that on the inlet side, and at the 52 m section, the dust concentration basically decreases to less than 100 mg/m3. When tunneling and shotcrete work simultaneously, the dust migration distance increases, and the dust concentration decreases to less than 100 mg/m3 at the section of 55 m. Through an orthogonal experiment, the optimal combination of working ventilation parameters is obtained. This study gives a helpful guidance for dust suppression when two or more dust production processes operate simultaneously.

Airborne high oil-content coal particles suppression via the electrolyte accelerated application of hydrocarbon and short-chain fluorocarbon surfactants

This paper studied the wetting and agglomerating behaviour of high oil-content coal particles, during the electrolyte accelerated synergistic application of hydrocarbon and short-chain fluorocarbon surfactants. The addition of short-chain fluorocarbon contributed 42.91 % ∼ 71.71 % reduction on surface tension and 51.08 % to 59.54 % reduction on immersing time. The short-chain fluorocarbon surfactant also achieves 29.17 % ∼ 258.93 % improvement on TSI and 48 % ∼ 104 % improvement on dust suppression rate. The presence of electrolytes further enhanced those performances by contributing an extra 7.95 % ∼ 18.41 % reduction on surface tension, 54.99 % ∼ 75.73 % reduction on immersing time for oil-rich and oil-high coal particles, 1.95 ∼ 19.16 times higher TSI and 23.35 % ∼ 31.85 % increasement on dedusting rate. The agglomerating behaviour is more accurate in predicting the dedusting rate. The increased oil content led to significant reduction on static and total liquid bridge force, and finally resulted in deteriorated dedusting rate due to the diminished wetting and agglomerating performance.

Development and performance characterization of a composite dust suppressant for Yellow River alluvial silt using response surface methodology

The construction site covered with Yellow River alluvial silt (YRAS) is prone to generate dust, which has always been troubling to the builders. The purpose of this study was to develop a composite dust suppressant aimed at YRAS dust for the first time. First, the formulation of composite dust suppressant was determined using the response surface methodology. Then, the mechanical properties and weather resistance of YRAS solidified layer, and the dust suppression efficiency and environmental performance of the composite dust suppressant were evaluated. The test results showed that the optimum mixing concentration of composite dust suppressant was 2.62% sodium alginate (SA), 2.37% carboxymethyl chitosan (CMCS), 0.21% polyacrylic acid sodium, and 0.85% sodium dodecyl sulfate. The YRAS sprayed with composite dust suppressant formed a solidified layer with sufficient hardness and compressive strength. The YRAS solidified layer had good freeze-thaw resistance, rain erosion resistance, and wind erosion resistance. The composite dust suppressant effectively reduced the concentration of total suspended particulate, PM10 and PM2.5 produced by YRAS, and the effect could last for one month. The composite dust suppressant was non-toxic, low metal corrosive and degradable, and its main raw materials (SA and CMCS) were obtained from nature. The above results show that the composite dust suppressant can effectively and long-term suppress the dust of YRAS, and is environmentally friendly and appropriate for clean production.

CFD-Based Numerical Simulation on the Combined Spraying Dust Suppression Device

Spraying for dust suppression is a conventional technological means for industrial dust control. The traditional spraying technique shows a few shortcomings, including low dust suppression efficiency, great water consumption, and failure in far-distance dust suppression. This study proposed a novel combined spraying dust suppression device and established the related physical model and mathematical model. Using the CFD numerical simulation method, the basic characteristics of the airflow field and spray field around the device and the related influencing factors were investigated in depth. Results showed that the Coanda effect appeared near the wall surface in the air duct when the combined spraying dust suppression device was operated. Under this effect, negative pressure formed at the center of the device. The velocity of the combined device showed a symmetrical distribution and decayed steadily downward from the outlet of the device. An obvious stratification can be observed in the spray field. The mean droplet size first increased and then decreased along the airflow direction. Meanwhile, the effects of the air supply pressure and water supply pressure were examined. On the one hand, the velocity of the combined spraying dust suppression device and the spraying range were in direct proportion with the air supply pressure. As the air supply pressure increased, the droplet size first increased and then decreased. On the other hand, increasing the water supply pressure imposed almost no effect on the airflow field of the combined spraying dust suppression device but can reduce the droplet size and enhance the spraying range.

Effect of glycerol microemulsion on coal seam wetting and moisturizing performance

In coal mining, coal seam water injection is effective for rock burst prevention and dust suppression, and the microemulsion as a water injection agent can greatly improve the wettability of coal seams. In order to further study the effect of glycerol in microemulsion as a phase substance on the wettability of coal body after water injection in coal seam, and its role in promoting coal seam moisturizing performance, on the basis of changing the phase material, the influence of different microemulsion components on the wettability of coal is explored through the contact angle experiment and Fourier infrared spectroscopy experiment, and the effect of glycerol on the moisturizing performance of coal is analyzed through the wettability control experiment in this paper. The experimental results show that the microemulsion as a wetting agent exhibits good wettability, and the composition of the microemulsion phase material affects the formation and dissociation of the functional groups on the coal surface by the microemulsion to a certain extent. The dissociation of the functional groups on the coal surface by the surfactant components in the microemulsion dominates the wetting mechanism of coal, and the effect of glycerol molecules on the functional groups shows a certain degree of wetting promotion. In addition, glycerol molecules easily react with other molecules such as water and sulfur dioxide molecules. After being injected into the coal seam, the glycerol microemulsion has a good moisturizing effect and a certain effect of coalbed methane purification. Therefore, it has practical significance for reducing coal dust concentration on coal mining face and increasing coal seam permeability.

Study on Temporal and Spatial Distribution and Transport Characteristics of Dust in New Composite Spraying Slurry

In view of the problems of traditional spraying technology, such as complex processes, high costs, large dust amounts, and poor air leakage effects, a new composite spraying slurry is proposed in this paper, which takes clay as the main base material and uses water pressure and wind pressure to ensure intrinsic safety. Firstly, the airtightness, bending resistance, and viscosity of the spraying material were measured in the laboratory; secondly, the gas–liquid–solid three-phase flow process involved in the spraying process was simulated by using the CFD-DPM method, adopting the Eulerian two-fluid model for continuous gas–water two-phases and the discrete phase DPM model for dust generation, and the transport, diffusion, and full space-time distribution characteristics of dust generation were studied. The research shows that: (1) the new composite slurry spraying material made of clay as the main material is made by adding a small proportion of cement and engineering fiber to increase the toughness of the material, and finally, determining the mass ratio of the composite material as follows: clay: cement: additive: engineering fiber = 84:14:1.85:0.15. It has good sealing and bending resistance and good adhesion; (2) the water phase distribution under the action of spray determines the distribution of solid-phase dust, and the distribution area of dust is similar to that of the water phase; (3) under the action of spray, the area at the bottom of the roadway is covered by dust flow, and the dust in this area is obviously stratified. The particle size of the dust gradually decreases from bottom to top. The large particle size dust is deposited at the bottom, while the small particle size dust is suspended at a certain height, and the diffusion area gradually increases; (4) the effect of spray angle on dust is mainly manifested in the initial dust flow shape and dust diffusion time. The larger the spray angle, the faster the diffusion; (5) when the water velocity at the nozzle outlet is large, the dust concentration is low in the whole area, but in areas higher than 1.5 m, the PM2.5 concentration also increases with the increase in water flow. The dust suppression effect of larger a water flow is mainly reflected in the bottom area, and the disturbed surrounding airflow can make PM2.5 diffuse to higher areas.

Surface pore characteristics of original coal dust produced in underground mining sites and their impact on the moisture content

In underground coal mines, the efficiency of water-based dust suppression technologies is heavily limited by the poor wettability of coal dust. To explore the effect reasons of the surface pore parameters of coal dust on its wettability, in this study, 18 original coal dust (OCD) samples produced in underground mining sites were collected from various underground coal mines in north China. The surface micropore (pore size <2 nm) and mesopore (2 nm < pore size <50 nm) characteristics of the OCD samples were measured with the nitrogen (N2) adsorption/desorption method. Subsequently, the correlations between the pore characteristics of the OCD samples and their moisture contents and initial contact angle (ICA) were established and discussed. The results demonstrate that the pore structures of the OCD samples are significantly developed, and the impermeable pores with one open end are the dominant pore types in the OCD. The micropore structure of the OCD samples considerably affects its moisture content, thus influencing its wettability. As the increase of micropore size, micropore volume, and specific surface area (SSA), the moisture content of the OCD samples linearly decreased (R2 =0.55), linearly increased (R2 =0.66), and linearly increased (R2 =0.65), respectively. The large capillary force caused by the developed SSA accounts for the significant moisture conservation property of the micropore structures, which improves the wettability of the OCD. The variation of the ICA with the pore parameters well verifies this conclusion.

Environmental Impact Assessment of Production Plant during Construction Period

Based on the construction project of a manufacturing plant, the environmental impact assessment of possible environmental pollution during the construction period was carried out from the perspective of atmosphere, water, noise, and solid waste. The analysis of air pollution indicates that dust and motor vehicle exhaust are the main air pollution factors, of which dust emission is 33 t, and the daily emission of NOx, CO, and THC in tail gas is 5.35 kg, 3.7 kg, and 1.1 kg, respectively. The annual average wind speed of the area where the factory is located is 3.15 m/s, and the average wind speed in August is 2.50 m/s, which is 20.6% lower than the annual average. The annual average monthly precipitation is 59.5 mm, and the precipitation in July is 186.4 mm, which is 213.3% higher than the monthly average. Therefore, summer is the best time for construction. Meanwhile, in addition to taking road hardening measures to reduce emissions, dust can also be restrained through watering, and motor vehicle exhaust is reduced through reasonable operation. Water pollution analysis shows that the pH of groundwater in the factory is within the standard limit range (6.5-8.5), and the maximum standard index is less than 0.1, with a very high level of reaching the standard. Cleaning engineering machinery will produce wastewater containing petroleum substances and suspended solids. The amount of wastewater produced every day is 0.5 m3, which can be used for dust suppression. The daily amount of sewage during the construction period is 0.6 m3, which can be directly discharged to the pipe network without polluting local water sources. Noise pollution analysis shows that the minimum distance between day construction and night construction is 50 m and 281 m, respectively. Although there is large construction machinery in the construction area, the construction area itself is in the production area and there are other noise pollution sources around it, so there will not be obvious noise pollution during the construction period. The analysis of solid waste pollution indicates that the total amount of construction waste generated during the construction period is about 4.2 t, and the daily production of domestic waste is 21 kg. Part of various solid wastes is collected and treated in a centralized manner, while the rest can conducted with landfill treatment after part of them is recycled and utilized, without causing significant pollution to the local environment.

Carboxymethyl cellulose sodium gel: A modified material used to suppress coal dust pollution

To reduce the environmental pollution caused by coal dust, a new type of dust inhibitor with a wide application range, high efficiency, and production simplicity was synthesized by modifying sodium carboxymethylcellulose (CMC-Na) with acrylamide (AM). Through molecular dynamics simulations and experiments, the surfactant composition and concentration were optimized. The experimental results showed that the graft copolymer of CMC-Na and AM (CMC-Na-co-AM) had more pores on the microscopic surface and a unique fiber network structure, which greatly increased its contact area with coal dust. After 14 h of drying at 60 °C, coal samples that were sprayed with the dust suppression agent retained >50% of the water in the spray, which was 9 times greater than the water retention of coal samples sprayed with just water. Additionally, the ability of the dust suppression agent to resist wind erosion was 6 times that of water. The CMC-Na-co-AM dust suppression agent showed that it could effectively inhibit the spread of coal dust under strong winds, offering a solution to the problem of coal dust pollution in coal production and storage.

Study on the adsorption and dust suppression mechanism of urease-producing bacteria on coal dust

Microbial dust suppressants are currently receiving extensive research attention, as they provide an efficient and low-environmental impact approach to dust suppression. The adsorption of urease-producing bacteria on coal dust is a key factor in the action of microbial dust suppressants, determining the release of urease and enhancing dust consolidation performance. However, to date, few studies have been carried out on this and therefore, the dust suppression mechanism of microbial dust suppressants remains unclear. In order to comprehensively explore the dust suppression mechanism of microbial dust suppressants, the adsorption characteristics and mechanism of interaction between coal dust and the urease-producing bacterial strain Bacillus X4 ( B. X4) were studied. In addition, the relationship between adsorption performance and dust suppression efficiency was determined. It was found that the adsorption capacity of B. X4 bacteria was the highest for 40–80 mesh coal (40.71 mg/g), exhibiting a 1.61-fold greater adsorption affinity that for 120–200 mesh coal dust. Scanning electron microscopy (SEM) and adsorption isotherms showed that large quantities of bacteria could be adsorbed on the surface of coal dust, with bacteria adhering via monolayer adsorption. Fourier transform infrared (FTIR) spectroscopy analysis showed that the amide group on the surface of bacteria was the main active group for bacterial adsorption to coal dust. The results of contact angle measurements and molecular dynamic simulations demonstrated that B. X4 bacteria improved the wettability of water on the surface of coal dust. Furthermore, larger coal dust particle sizes resulted in a higher content of calcium carbonate being produced after spraying the microbial dust suppressant. The microbial dust suppressant achieved the best dust suppression performance when sprayed on 40–80 mesh coal dust, which was consistent with the adsorption analysis results, indicating that the adsorbed amount of microorganisms on coal dust was positively correlated with the dust suppression effect. • Urease-producing bacteria formed a monolayer on coal dust with uneven adsorption. • Adsorption mainly involved amide groups on the urease-producing bacteria surface. • Dust suppression was positively correlated with bacterial adsorption on coal dust.

Research on a quality detection system of dust suppression spraying for railway coal transportation using laser backscattering technology

Aiming at the low efficiency of manual sample inspection of dust suppression spraying quality in railway coal transportation, a detection system combining a high-pressure gas spraying and laser backscattering detection technology is presented in this paper. In terms of hardware, it is composed of gas excitation, powdered coal concentration detection and a control unit. The gas excitation device, including nozzle, camera and electric control platform, is designed for realizing the dust suppressant spraying quality detection by nozzle jet gas impacts on a coal surface. In terms of software, the programs for the system were developed based on the LabVIEW development platform, realizing the system parameter adjustment, detection signal display, gas excitation control and real-time data storage functions. Experimental results show that the gas pressure of the field test should be maintained at 0.9 MPa–1.23 MPa and the distance between the equipment and the target vehicle is more than 2000 mm. The proposed system can detect 3–4 times spot checks with a single carriage for the train under the speed of 3 m s−1–5 m s−1, which solves the problems of low efficiency and high risk of manual detection.

Comparison of static tests and dynamic tests for coal dust surfactants evaluation: A review

Coal workers’ pneumoconiosis is one of the most severe occupational diseases due to long-term exposure to high concentrations of coal dust. Water spray with surfactant addition is an effective and commonly used method to control the coal dust in coal mines. Usually, the surfactant evaluation methods can be divided into two categories, including static and dynamic tests. The performance of surfactants may vary with different evaluation methods, which make the results hard to conclude. By critically reviewing previous studies, this paper highlighted the four surfactants’ evaluating methods for coal dust suppression, including the surface tension test, the sink test, the field test, and the wind tunnel test. Firstly, the basics of four evaluating methods were described, and the general result was concluded and presented. Secondly, static and dynamic tests were compared to reveal the consistency and discrepancy. It was found that the surface tension test takes dominations at lower concentrations of surfactants, while it cannot further take advantage after a critical concentration. The anionic and non-ionic surfactants showed better performance than cationic surfactants mostly in static tests. The field test and the wind tunnel test can directly evaluate the suppression efficiency of surfactants, with consideration of environmental factors such as the particle collision and the contact time. This paper is important for producing comparable results between static and dynamic tests and revealing the consistency and discrepancy. The outcomes of this study could be a guidance for evaluating and selecting the optimum surfactants for coal dust suppression.

Characteristics of a Cavitating Spoiler Mixing Device and Its Performance in a Foam Dust Suppression System.

The unsteady foaming-agent mixing ratio in traditional foam-dust-suppression technology limited the dust suppression efficiency. Recent studies proved that the steady mixing ratio could be guaranteed by keeping the jet pumps or Venturis working under cavitation conditions, but the pressure loss of the current devices was over 50%. To decrease the pressure loss under cavitation conditions, we proposed a new mixing device by introducing a spoiler in the Venturi structure. Through computational fluid dynamics (CFD) simulation, the spoiler structure influence on the downstream flow field and the cavitation cloud structure, which affected the total pressure loss of the device, were revealed. For structure optimization, the effect of the other geometric parameters, including the throat length and divergent angle, on the pressure loss was also studied. The proposed device enhanced the cavitation on the suction tube side of the throat; meanwhile, the cavitation in other parts of the device was avoided. Therefore, the cavitation zone in the proposed device was much smaller than that in current devices, and the pressure loss was reduced significantly. When the flow ratio was 0.5–1%, the critical pressure ratio of the proposed mixing device was 0.71–0.68, which indicated that the pressure loss was only 29%–32%. The laboratory experiment verified that when the proposed device worked under cavitation conditions, the accurate and steady mixing ratio was guaranteed. The field experiment indicated that due to the reduced pressure loss of the proposed device, the required water inlet pressure decreased to 0.29 MPa, and the dust suppression rate increased dramatically. This study was of important value in manipulating cavitation cloud structure using a spoiler, clarifying the influence of the cavitation cloud structure on the liquid mixing performance and expanding the application field of the cavitating mixing method.

The effects of roadways on lakes and ponds: a systematic review and assessment of knowledge gaps

As the global population increases, the expansion of road networks has led to the destruction and disturbance of terrestrial and aquatic habitats. Road-related stressors have significant effects on both lotic and lentic habitats. While there are several systematic reviews that evaluate the effects of roads on lotic environments, there are none that consider their effects on lentic habitats only. We conducted a literature review to achieve two objectives: (1) to summarize the effects of roads on the physical, chemical, and biological properties of lentic environments; and (2) to identify biases and gaps in our current knowledge of the effects of roads on lentic habitats, so that we could find promising areas for future research.Our review found 172 papers published between 1970 and 2020. The most frequently studied stressors associated with roads included road salt and heavy metal contamination (67 and 43 papers, respectively), habitat fragmentation (37 papers), and landscape change (14 papers). These stressors can lead to alterations in conductivity and chloride levels, changes in lake stratification patterns, increases in heavy metal concentrations in water and organisms, and significant mortality as amphibians disperse across roadways. We also identified a variety of other stressors that may be understudied based on their frequency of appearance in our search results, including polycyclic aromatic hydrocarbons, road dust, increased accessibility, hydrological changes, noise pollution, dust suppressants, sedimentation, invasive species introductions, and water withdrawal.Our review indicated that there are strong geographic biases in published studies, with 57.0% examining North American sites and 30.2% examining European sites. Furthermore, there were taxonomic biases in the published literature, with most studies focusing on amphibians (41.7%), fish (15.6%), and macroinvertebrates (14.6%), while few considered zooplankton (8.3%), diatoms (7.3%), amoebas (5.2%), water birds (3.1%), reptiles (2.1%), and macrophytes (1.0%). Based on our review, we have identified promising areas for future research for each of the major stressors related to roadways. However, we speculate that rectifying the geographic and taxonomic bias of our current knowledge could significantly advance our understanding of the impacts of roads on lentic environments, thereby better informing environmental management of these important habitats.

Comprehensive Evaluation of Dust Retention and Metal Accumulation by the Leaves of Roadside Plants in Hangzhou among Seasons

The auto exhaust and dust derived from increased traffic volumes have led to an increasing level of atmospheric particulates in urban areas, which have become a primary pollutant of ambient air in urban zones. Roadside plants can effectively retain atmospheric particulates and clean the urban air via foliar capture of road dust. Five common roadside plants in Hangzhou were selected to evaluate their capacity for the retention of particulate matter (PM) and the accumulation of metals. The results showed that the PM retention capacity of the different plants varied greatly, as was the case with Loropetalum chinense var. rubrum Yieh, Osmanthus fragrans (Thunb.) Loureiro, Pittosporum tobira (Thunb.) Ait, Photinia × fraseri Dress and Cinnamomum camphora (L.) Presl. In addition, the amounts of particles retained by the plants varied among seasons, with the highest retention in winter (12.19 g·m−2) and the lowest retention in spring (6.89 g·m−2). The solids on the leaf surface were mainly irregular particles, such as mineral fragments, soot aggregates, and fly ash particles. Meanwhile, these plant species can effectively accumulate heavy metals that attached to the particles. The leaves of the five tree species had the highest amounts of copper (Cu) and the lowest amounts of cadmium (Cd). Among species, L. chinense and P. tobira had the strongest comprehensive capacity to adsorb particulate matter and heavy metals. The results shed light on the rational selection of road plants, both as ornaments and to purify air via dust suppression in subtropical zones.

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability.

The atmospheric dust has a great negative impact on the societal harmonious development that starves for an efficient dust suppressant. This paper proposes a novel AES/polyacrylamide strengthen foam (APSF) to improve the dust trapping effectiveness. The APSF structure property and dust suppression capacity are studied and evaluated through the molecular dynamics simulation and experimental tests. The results express that APSF exhibits the stronger structure stability, superior water retention, and slower drainage performance than the traditional water-based foam (WBF). APSF dynamic simulation is studied by the relative concentration, radial distribution function, head group orientation, and mean square displacement. Research shows that APSF introduces water to thicken the hydration layer. The interaction strength between water and surfactant head groups is enhanced by 22.62 and 31.37% in the first and second hydrated water shells. APSF improves the sodium fatty alcohol ether sulfate (AES) orientation and weakens the diffusion of water molecules, which favors the foam stability. APSF exerts a better wettability on the coal dust through the wet settlement and contact angle tests. The APSF liquid film thickness reduces to 58.05 from 64.80 μm that is 3.14 times of WBF according to the foam liquid film decay experiment. Fourier transform infrared (FTIR) spectroscopy analysis indicates that there is an evident reinforcement on the coal surface absorption peak intensity of hydroxyl- and oxygen-containing functional groups treated by APSF. FTIR results are further determined by energy-dispersion spectrum analysis.

Synthesis and performance of a novel high-efficiency coal dust suppressant based on biopolysaccharide-xanthan gum

The coal production process produces a lot of dust, which pollutes the environment and threatens the occupational health of workers. Although many dust suppressants for coal dust control have been developed, the implementation of current dust suppressants does not meet the requirements due to their poor foaming, stability, and wettability effects. In our current study, the effect of xanthan gum (XG) on the properties and foaming ability of the composite surfactant ALAP has been investigated. The research shows that with the increase of CXG, the foaming volume of the solution increases by nearly 30% on average. The liquid-carrying capacity, the foaming delay period, and the liquid-draining half-life of the foam are also improved, while the performance of wetting coal dust decreases. Compared with traditional water-soluble polymers, XG molecules have a special double helix structure and plenty of polar functional groups, which can form a stable 3D network system with surfactant molecules. XG molecules could not only effectively improve the foaming performance of low-concentration ALAP, the liquid-carrying ability, and the stability of foam, but also reduce the burst rate of the bubbles. In our investigations, the dust reduction effect of the XG/ALAP systems have been comprehensively evaluated through the field application of the heading face. The dust reduction efficiency of total dust and respirable dust can reach nearly 90% and 85% respectively, which is 2.2 times and 2.5 times higher than that of water spraying. The XG/ALAP systems also effectively improve the visibility of the working surface. With the consideration of all the above-mentioned factors, the composition range of the high-efficiency dust suppressant is obtained as: 0.7‰≥CXG ≥ 0.5‰ and 4‰≥CALAP ≥ 3‰.

Ecological Monitoring Method and Tools for Dust Suppression during Coal Transportation and Storage

Ecological Monitoring Method and Tools for Dust Suppression during Coal Transportation and Storage

Study on Dust Suppression of Air Curtain Soft-Sealing System of Grab Ship Unloader

In order to suppress the irregular diffusion of dust in the unloading process of grab ship unloaders, an air curtain soft-sealing system was designed that can effectively block the air flow and restrict the diffusion of pollutants and reduce the average mass fraction of pollutants outside the air curtain plane by 70.02%. The grab unloading model was constructed using the Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) coupling method, and the diffusion law of the gas–solid two-phase flow field of the falling bulk material was studied. Moreover, the motion trajectory and velocity distribution of the particle flow field and air flow field were obtained, as well as the maximum air flow field velocity of five planes above the hopper. The three-dimensional model of the air curtain jet was used and simplified, and the air curtain parameters were set based on the maximum air flow field velocity. The barrier performance of the air curtain under different air curtain jet modes, jet widths, jet velocities and induced wind velocities was simulated by the control variable method. The results show that selecting the appropriate jet widths and jet velocities can significantly reduce dust diffusion; under different jet modes, the order of influence was blow and suction, unilateral blowing and bilateral blowing; under a certain range of induced wind velocities, the air curtain had an obvious blocking effect. These results can provide a reference for the design and improvement of dust suppression of the air curtain soft-sealing system.