Chemical dust suppression is an effective dust control technology. A dust suppressant component evaluation method that facilitates a complete selection of safe, efficient, and economical chemical materials has not been explored. Considering dust suppression performance, environmental safety, and cost-effectiveness of chemical dust suppressant technology, this study constructs a comprehensive evaluation index system of chemical dust suppressant performance, including the wetting performance, hygroscopic performance, bonding performance, annual cost per unit area, pH value of dust suppression solution, chemical toxicity, and chemical corrosion. Among them, the index characterizing the wetting performance of the solution is the sedimentation wetting time, which is determined by the dust sedimentation experiment; the index characterizing the hygroscopic performance of the solution is the evaporation stability time, which is determined by the evaporation experiment of the solution on the dust surface; the index to characterize the bonding performance of the solution is the surface wind erosion rate, which is determined by the wind erosion experiment of the solution on the dust surface; the toxicity of the solution is evaluated by the LD50 of the solution; the index to characterize the corrosion performance of the solution is the Q235 monthly steel corrosion rate, which is determined by the Q235 steel corrosion test. Corresponding evaluation parameters are determined including sedimentation wetting time, evaporation stabilization time, surface wind erosion rate; annual average use cost per unit area; solution pH value, chemical acute toxicity classification, monthly corrosion rate of Q235 steel, and corresponding standard test methods are also provided. In order to evaluate the comparability of the results, according to the specific requirements of the evaluation index system and the distribution characteristics of the measurement data, the data of each evaluation and detection index are standardized by linear transformation, range transformation and other methods, so that the obtained results are comparable. Considering the differences in the actual performance requirements of dust suppressants in different usage scenarios, the weights of evaluation indicators at all levels can be set independently and flexible. The experimental test data obtained through the example shows that: among the four chemicals selected to participate in the experiment, the comprehensive dust suppression performance score of Triton X-100 solution is in the poor-grade category. The comprehensive dust suppression performances of calcium chloride solution, water, and polyacrylamide solution scored high in the average-grade category. The comprehensive evaluation process is logically correct, and the results are consistent with the phenomena observed in the experiment, consistent with conventional understanding, and have strong credibility. This method can provide a standardized evaluation technique and test process for the comprehensive performance evaluation and comparison of chemical materials and dust suppressants.
To investigate the influence of surface tension and viscosity on the atomization performance of solid cone nozzles and improve their dust reduction efficiency in industrial and mining enterprises, this study employed a self-built PDPA dust-fog coupling experimental system to explore the effects of different surface tension and viscosity solutions on atomization performance from three aspects: axial, radial, and fog field distribution. The experimental results indicate that compared with surface tension, surface tension has a greater influence on droplet size and velocity in the axial direction. In the radial direction, increasing surface tension and reducing viscosity within a certain range can make the droplet size and velocity distribution more uniform. Additionally, surface tension and viscosity significantly affect the fog field distribution. It was found that a decrease in surface tension can result in a closer proximity of the droplet velocity and size expansion area to the nozzle, while an increase in viscosity can lead to a more prolonged stable area. Furthermore, optimizing the surface tension and viscosity can significantly enhance the efficacy of dust reduction for respirable dust. Consequently, the application of the aforementioned atomization principles to regulate the fog field characteristics of solid cone nozzles can effectively mitigate dust in the production process and augment the dust reduction rate of industrial and mining enterprises.
To adjust the thermal safety of hydrophobic silica aerogel, layered double hydroxide (LDH)/silica aerogel (SA) composites were prepared by an in-situ sol-gel process at ambient pressure. This study found the physical combination of SA and MgAl-LDH based on the FTIR spectra and phase composition of LDH/SA. The N2 sorption analysis confirms that the introduction of MgAl-LDH does not change the mesoporous attribution of LDH/SA significantly. With the increase in MgAl-LDH addictive content, the low density (0.12–0.13 g/cm3), low thermal conductivity (24.28–26.38 mW/m/K), and large specific surface area (730.7–903.7 m2g) of LDH/SA are still maintained, which can satisfy the requirements of thermal insulation. The TG-DSC analysis demonstrates that the endothermic effects and metal oxides formed during the MgAl-LDH decomposition are beneficial to the improvement of the thermal stability of LDH/SA composites. In addition, it was found that the gross calorific values of LDH/SA composites decrease with an increase in MgAl-LDH addictive content, all of which are lower than that of the pure SA. The research outcomes indicate that the thermal safety of LDH/SA composites is enhanced significantly by doping MgAl-LDH without impairing too many of the excellent properties, which benefits their expansion in the thermal insulation field.
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.
In this work, we reported that aramid pulps (AP) reinforced clay aerogel composites with improved mechanical strength, good thermal insulation and fire resistance based on the combination of AP, Poly(vinyl alcohol) (PVA) and sodium montmorillonite (MMT), which present a promising prospect in the thermal insulation application. The PVA-MMT-APx (x: denotes the mass content of AP) aerogel composites present an isotropic “lamella-honeycomb” porous structure, which endows them with excellent comprehensive performance. With the AP content increasing, the extremely low density is kept, ranging between 67–73 mg/cm3, and the low thermal conductivity is maintained within 40.9–47.9 mW·m−1·K−1. The mechanical strength is significantly improved with the maximum compressive modulus increasing from 2.95 to 5.96 MPa and the specific modulus rising from 44.03 to 81.64 MPa∙cm3/g. Their detailed heat transfer process has been analyzed, which provides a deep understanding to the low thermal conductivity of the PVA-MMT-APx aerogel composites. Based on the combination of thermogravimetric analysis and combustion behavior, the PVA-MMT-APx aerogel composites are demonstrated to possess improved thermal stability and fire resistance. This study puts forward a facile approach to utilizing AP to reinforce clay aerogel composites, which provides new insight into the development of thermal-insulating, fire-safe and high-strength thermal insulation materials.
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