Synthesis and performance measurement of environment-friendly solidified dust suppressant for open pit coalmine

Effect of Sodium Carboxymethyl Cellulose on the Dynamic Wetting Characteristics of the Dust Suppression Droplet Impacting the Coal Surface

The dynamic wetting behavior of droplets impacting the coal surface directly affects the efficient application of water-based dust suppression materials in coal-related industrial production. In this paper, ultrapure water, Tween-80, and sodium carboxymethyl cellulose are taken as the research objects. Using high-speed photography technology, the spreading, oscillation process, and splash morphology of many kinds of droplets during impacting the coal surface are captured. The effects of viscosity, surface tension, and impact velocity on dynamic wetting characteristics were studied. The results show that with the decrease of surface tension, the retraction and oscillation of droplets are significantly reduced. For the same kind of droplets, the greater the impact velocity, the faster the droplet spread, and the dimensionless maximum spreading coefficient (β_max) and dimensionless steady-state spreading coefficient (β_e) of droplets are bigger. With the increase of velocity, the time for different kinds of droplets to reach the β_max increases. At the same impact velocity, β_max and β_e of droplets (0.2% Tween-80 + 0.1% sodium carboxymethyl cellulose) are the largest, indicating that adding a small amount of sodium carboxymethyl cellulose can promote droplet spreading. With the increase of sodium carboxymethyl cellulose content, β_max and β_e decreased gradually. The results have a great significance to the research, development, and scientific utilization of water-soluble polymer dust inhibitors.

Experimental study on ratio optimization and application of improved bonded dust suppressant based on wetting effect

Traditional bonded dust suppressants have high viscosity, insufficient fluidity and poor permeability problems, which is adverse to the formation of a continuous and stable solidified layer of dust suppressant solution on the surface of a dust pile. Gemini surfactant has efficient wetting performance and environmental protection performance, it is introduced as a wetting component to improve the flow and penetration performance of bonded dust suppressant solution, polymer absorbent resin (SAP) and sodium carboxymethyl starch (CMS) were selected as the main components of dust suppressant. A proportioning optimization model was constructed based on response surface methodology (RSM), and the concentration of each dust suppression component was selected as the independent variable, water loss rate, moisture retention rate, wind erosion rate and solution viscosity were chosen as the dependent variables in this model. The optimal formulation of the improved bonded dust suppressant was obtained by analyzing the laboratory experiments and field tests data. The results show that the effective time (≥15d) of the newly developed dust suppressant is 45 times longer than that of pure water (≈1/3d), and 1.875 times longer than that of the comparative dust suppressant (8d), the comprehensive cost is 27.36% lower than that of the similar dust suppressant product for mining enterprises.Implications: This paper presents the research idea of optimizing the bonded dust suppressant based on the improvement of wetting performance. And the paper used response surface method to obtain a wetting and bonding composite dust suppressant formulation. The field test shows that the dust suppressant has good dust suppression performance and economic benefits. This study laid the foundation for the development of new and efficient dust suppressants, and had important theoretical and application values for reducing dust environmental hazards and preventing occupational diseases.

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.

Adsorption Characteristics of Ionic Surfactants on Anthracite Surface: A Combined Experimental and Modeling Study

Ionic surfactants are widely used in coal dust control in mines, and their adsorption characteristics on the coal surface have a great influence on the coal dust control effect. In this investigation, anionic sodium dodecylbenzenesulfonate (SDBS) and cationic octadecyltrimethylammonium chloride (STAC) were selected to explore the adsorption characteristics of ionic surfactants on the surface of anthracite. The experimental results show that the adsorption rate and efficiency of STAC on the surface of anthracite are higher than that of SDBS; STAC can form a denser surfactant layer on the surface of anthracite, with a larger adsorption capacity and higher strength. Molecular dynamics simulations show that the adsorption between STAC and the surface of anthracite is tighter, and the distribution at the coal–water interface is more uniform; the surface of anthracite modified by STAC has a stronger binding ability to water molecules.

Annual dust pollution characteristics and its prevention and control for environmental protection in surface mines

Dust pollution is a critical challenge in achieving green mining of open-pit coal mines. The scientific basis for dust prevention and management hinges on a thorough understanding of the long-term characteristics of dust pollution. However, analyzing the characteristics of long-term dust pollution in open-pit coal mines has always been a void in research due to the effect of the mines' geographical location and operating conditions. This research investigated the dust pollution and delved into its key production and meteorological influencing elements in a cold-region open pit coal mining. The real-time data was monitored on-site during the four seasons of the year. The characteristics of dust pollution were determined by statistical analysis. The main factors affecting the dust concentration in different seasons were calculated using the comprehensive grey correlation degree. Finally, dust pollution from the mine to the surrounding area was simulated using the Hybrid Single Particle Lagrangian Integrated Trajectory model. The results revealed that dust pollution was most serious in winter, followed by autumn, spring, and summer. The concentrations of PM10 and PM2.5 exceed the national limit. Meteorological elements that substantially impact dust concentration vary season by season. The dew point temperature in spring, the solar radiation in summer and autumn, and the boundary layer height in winter were the most important elements. Mining activities pollute the surrounding areas more in winter, followed by autumn and spring. During the winter, the pollution is concentrated in Shanxi, while in the autumn and spring, it is concentrated in Inner Mongolia. Based on the research findings, optimal mine design strategies can be devised to avoid and regulate dust in mining and neighboring areas, especially during winter.

Experimental Study on Dust Suppression Effect and Performance of New Nano-Composite Dust Suppressant

In this paper, a nano-composite dust suppressant has been proposed to make up for the deficiency in wettability and moisturizing performance of a nanofluid dust suppressant. The nanometer material Al₂O₃, super absorbent polymer, carboxyl methyl starch sodium, and polyacrylamide were selected as effective components of it. The surface tension of the solution, evaporation resistance, and uniaxial compressive strength (UCS) were chosen as evaluation index to compare the suppression performance, these dust suppressants include the water, nanofluid dust suppressant and nano-composite dust suppressant, and the surface morphology of each tested material was observed by micro image analysis system. It was found that the surface tension and water loss rates of the nano-composite dust suppressants, respectively, decreased by 31.96% and 7.1%, and the maximum UCS increased by 31.82% compared with data of nanofluid dust suppressants. Since the nano-composite dust suppressant has good dispersion, permeability and bond performance, the suppressant film has fewer micro-cracks from the photos of microscopic image; it can improve the compactness and integrity of dust consolidation to prevent the evaporation of water and dust re-entrainment.

Investigation on flow field characteristics in an open-pit coal mine

In this paper, the atmospheric flow field characteristics in a deep open-pit mine are investigated numerically and theoretically. A theoretical model on the recirculation length based on the energy equation is used, and a total variation diminishing (TVD) difference scheme with second-order accuracy is used to solve the NS equations with a standard two-equation k-ε turbulence model. The effects of elevated inner dump on the flow field characteristics of the open-pit mine are analyzed detailedly with the same inflow parameters. The results show that a recirculation zone exists in the open-pit mine due to the reflux from the high-pressure zone to the low-pressure zone. As the height of the inner dump increases, the flow becomes more complicated, and the low-pressure zone and the recirculation zone become bigger. The elevated inner dump makes it difficult for the internal fluid to flow to the outside, which results in the increase of the dust concentration. At last, the influences of key parameters on flow filed are conducted by normalizing the depth of the lowest direct current flow on the windward slope. The sensitivity analysis is done by study each influencing factor. This paper offers an effective way to study the flow field characteristics in an open-pit coal mine, which is essential to the dust pollution control of open-pit mine.

Dust pollution in cold region Surface Mines and its prevention and control

The application of traditional dust reduction methods in surface mines is limited, particularly during winter due to long-term drought and a rainless environment. Therefore, it is essential to investigate dust pollution in cold region mines and get insights into its scientific prevention and control. This research analyzed dust pollution (concentration of TSP, PM10, PM2.5) from a combined perspective of production and metrological conditions in the Haerwusu open pit coal mine located in northwest China to provide the basis for prevention and control. The main findings indicate that the dust concentration in the pit exceeds the national regulatory limit of 50 μg/m for PM10 and 35 μg/m for PM2.5. According to the air quality index, PM10 was the primary pollutant at the bottom of the pit where coal mining was occurring. The order of the factors influencing dust concentration was as follows: coal production > boundary layer height > wind speed > temperature difference > temperature > humidity. Our study revealed that mining activity polluted the surrounding areas, mostly in December and January. The southeastern and eastern regions of the mine site were found to be the most polluted areas. The implications of this study could be used to optimize mining operations and develop dust prevention and control strategies.

Preparation and performance characterization of a new dust suppressant with a cross-linked network structure for use in open-pit coal mines

In an effort to control dust pollution in open-air environments such as pit coal mines and coal transportation systems, a new dust suppressant with a cross-linked network structure was prepared. Graft copolymerization of soy protein isolate (SPI) and methacrylic acid (MAA), using potassium persulfate (KPS) as the initiator and hexametaphosphoric acid (SHMP) as the cross-linking agent, formed the network structure. The optimal MAA/SPI mass ratio for the dust suppressant was determined through a single-factor experiment to be 3:4, with 0.8 and 0.2 g of SHMP and KPS, respectively. The grafting reaction required 30 min at 60 °C. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, Fourier-transform infrared spectroscopy, and differential scanning calorimetry were used to characterize the structure and application performance of the dust suppressant. The experimental results showed that the graft copolymerization reaction successfully formed the desired cross-linked network, and that when the cross-linked network material was sprayed on coal dust, it formed a dense, solidified shell, which effectively resisted wind erosion and served as a dust suppressant. The average reduction of the total suspended particulate matter of an open-air coal pile reached 79.95%, demonstrating effective dust suppression.

Preparation, characterization, and in vitro release kinetics of doxorubicin-loaded magnetosomes

The doxorubicin (DOX) was successfully coupled to the magnetosomes from Acidithiobacillus ferrooxidans (At. ferrooxidans) by genipin bridging. The parameters (magnetosome concentration, DOX concentration, genipin concentration-, and cross-link time) expected for temperature significantly influenced the coupling rate. Bacterial magnetosome-doxorubicin complexes (BMDCs) were characterized by transmission electron microscope (TEM), particle size analyzer and Fourier transform infrared spectroscopy. Results indicated that BMDCs exhibited a mean particle size of 83.98 mm and displayed a negative charge. The chemical reaction occurring between CO and NH group and the physical adsorption predominated by electrostatic interaction were found to involve in coupling. BMDCs can release 40% of DOX in simulated gastrointestinal conditions within 38 h. Kinetic models including Higuchi, Korsmeyer-Peppas, Zero order, First order, Hixon-Crowell, Baker-Lonsdale, and Weibull and Gompertz were utilized to explore the release mechanism of DOX from BMDCs. All models were found to fit well (r² ≥ 0.8144) with the release data and the Gompertz was the best fit model (r² = 0.9742), implying that the complex mechanisms involving Fickian and Gompertz diffusion contributed to the release. These findings suggested that magnetosomes from At. ferrooxidans have great potential applications in biomedical and clinical fields as the carrier of target drug delivery systems in the future.

Preparation and characteristics analysis of an ecoenvironmental protection cyclic solidification dust-fixing agent extracted from waste shrimp shells to suppress dust in coal resource-based cities

There are a lot of coal cinder and dust in the development of coal resource-based cities. Improper handling will cause dust flying, which has a great impact on urban residents and the environment. The purpose of this research is to follow the principle of waste recycling, to use waste shrimp shells to extract chitosan as a raw material, to carry out graft polymerization with acrylic acid and polyvinyl alcohol-1788, and to carry out amidation crosslinking reactions with ethylenediamine tetraacetic acid to produce products. The results showed that the degree of deacetylation of chitosan reached 85% with the optimized extraction method, which greatly shortened the process cycle. Through orthogonal experiments and osmotic wetting experiments, the best preparation process was determined. The reaction process, structure of the product and adhesive structure of the solidified layer were analyzed by FTIR, XPS and SEM. The thermal stability of the product was analyzed by thermogravimetry. Relevant performance tests showed that the product had good adhesion with dust, the hardness of the solidified layer could reach 98 HA, and the dust fixation rate was 92.67% when the wind speed was 15-18 m/s. It has the advantage of circulating dust fixation, which improves the utilization rate of resources.

Environment-friendly dual-network hydrogel dust suppressant based on xanthan gum, polyvinyl alcohol and acrylic acid

Hydrogen bonding interactions among poly vinyl alcohol (PVA), xanthan gum (XG) and acrylic acid (AA) molecules have been utilized to prepare an environment-friendly interpenetrating double-network hydrogel dust suppressant (PVA-XG-PAA/SDBS) with the aim of enhancing the poor mechanical performance of current hydrogel dust suppressants. A single factor test was used to determine the optimal formulation conditions for the PVA-XG-PAA/SDBS, and the viscosity, surface tension, compression strength, wind resistance, water retention and biodegradability of the samples were measured. The results showed that the hydrogel with optimal usage contained 1.5 g, 0.1 g, and 6 g of PVA, XG and AA, respectively and the optimal reaction temperature was 55 °C. Under the optimal conditions, the viscosity was 45 mPa s, the surface tension was 30 mN/m, the compression strength of the dust suppressant-solidified coal pillar reached 126 kPa, and the degradation rate at the 8th cycle (40 days) after being buried in soil was 34%. Compared with a conventional hydrogel dust suppressant, like poly acrylic acid (PAA), and the dust suppressant sodium dodecyl benzene sulfonate (SDBS), the PVA-XG-PAA/SDBS showed better water retention, wind erosion resistance, and dust-solidifying properties. On the basis of these remarkable properties, the PVA-XG-PAA/SDBS is applicable for dust prevention during coal mining, transport, and storage, which enhances the dust suppression efficiency obviously and has significant meaning to the sustainable development of the coal mining industry while protecting the environment.

Preparation and Characterization of a Composite Dust Suppressant for Coal Mines

In an effort to effectively control coal dust pollution and thereby reduce the harm of coal dust to human health, we prepared a highly efficient composite dust suppressant. First, dynamic contact angle and zeta potential measurements were used to select sodium dodecyl sulfonate (SDS) over sodium carboxymethyl cellulose and trisodium methyl silicon as the complementary additive to soy protein isolate for the dust suppressant. We employed viscosity and wind erosion resistance tests to compare the performance of the composite dust suppressant with three common, commercially available suppressants. As the concentration of the composite dust suppressant was increased, the viscosity increased, reaching a maximum value of 22.7 mPa·s at a concentration of 5 wt%. The 5 wt% concentration of the composite dust suppressant provided the lowest wind erosion rate (20.62%) at a wind speed of 12 m/s. The composite dust suppressant also had good bonding performance and wind erosion resistance. Scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis were used to characterize the properties of the dust suppressants. The dust suppressant, which had a crystal-like structure, could easily capture coal dust and form an effective package. In addition, the density of the dust suppressant film increased as its crystallinity increased. The increased density was beneficial in that it enabled the dust suppressant to form a hard, solidified shell on the surface of coal dust, which improved dust suppression. The composite dust suppressant also had good thermal stability.

Effect of spraying on coal dust diffusion in a coal mine based on a numerical simulation

Aimed at effectively controlling coal dust pollution in the mining face of a coal mine, this study first conducted a theoretical analysis and then combined a spraying experiment and a numerical simulation to perform an in-depth examination of the atomizing characteristics and dust suppression performance of a coal cutter external spraying device. Based on the experimental spraying results, the optimal nozzle was determined to be a pressure round-mouth nozzle with an X-shaped core. The characteristics of the spray fields from nozzles of different calibers (1.6, 2.0 and 2.4 mm) at different spraying pressures (2, 4, 6 and 8 MPa) were then analyzed. It was found that the droplet concentration in the spray field increased with increasing spraying pressure and nozzle caliber. The droplet diameter was mainly dependent on the spraying pressure and varied more slowly with increased spraying pressure. At a spraying pressure of 8 MPa, the spray field formed could achieve effective dust suppression; specifically, the droplet concentration in the spray field was mostly more than 15 g/m³, and the droplet size was mainly distributed in the range of 30-100 μm. When using a 2.4 mm caliber nozzle, the dust concentration measured around the coal cutter operator was reduced to 87.21 mg/m³ under a spraying pressure of 8 MPa, suggesting adequate dust suppression.

Development of Environmental Friendly Dust Suppressant Based on the Modification of Soybean Protein Isolate

Aiming to further improve the dust suppression performance of the dust suppressant, the present study independently develops a new type of biodegradable environmentally-friendly dust suppressant. Specifically, the naturally occurring biodegradable soybean protein isolate (SPI) is selected as the main material, which is subject to an anionic surfactant, i.e., sodium dodecyl sulfonate (SDS) for modification with the presence of additives including carboxymethylcellulose sodium and methanesiliconic acid sodium. As a result, the SDS-SPI cementing dust suppressant is produced. The present study experimentally tests solutions with eight different dust suppressant concentrations under the same experimental condition, so as to evaluate their dust suppression performances. Key metrics considered include water retention capability, cementing power and dust suppression efficiency. The optimal concentration of dust suppressant solution is determined by collectively comparing these metrics. The experiments indicate that the optimal dust suppressant concentration is 3%, at which level the newly developed environmentally-friendly dust suppressant solution exhibits a decent dust suppression characteristic, with the water retention power reaching its peak level, and the corresponding viscosity being 12.96 mPa·s. This performance can generally meet the requirements imposed by coal mines. The peak efficiency of dust suppression can reach 92.13%. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to analyze the dust suppression mechanism of the developed dust suppressant. It was observed that a dense hardened shell formed on the surface of the pulverized coal particles sprayed with the dust suppressant. There is strong cementation between coal dust particles, and the cementation effect is better. This can effectively inhibit the re-entrainment of coal dust and reduce environmental pollution.