Coal dust is a primary threat to underground coal miners. The most common approach to control coal dust is hydraulic methods, such as water spray and coal seam water injection. To improve the dust suppressant efficiency of hydraulic methods, a novel chemical composite dust suppressant, called NCZ, was prepared in this study using calcium chloride (CaCl₂), magnesium chloride (MgCl₂), and nonionic surfactants using a thermal synthesis method. The water-retaining properties of NCZ powder and its solutions were characterized using the water absorption rate (WAR) and evaporation rate (ER), respectively, and the wetting abilities of the NCZ solutions on coal dust were tested using the initial contact angle (ICA) and sink rate (SR). The results indicate that the NCZ solutions have anti-evaporation effects, and the ER of the solution with a 20.0 wt% NCZ is reduced by 11.7% compared with that of clean water. Furthermore, NCZ solutions have remarkable enhancement effects on the wettability of coal dust. The ICA and SR of clean water and the NCZ solution at 20.0 wt% are 141.9° and 0 mg/s, and 29.3° and 1.46 mg/s, respectively. Finally, quantitative relationships between the solution surface tension and the ICA and IR were established using the least squares method. This study provides a new product for dust suppression in underground mines, which is significant for the optimum applied concentration of dust suppressant in mining operations.

To investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

Coal dust pollution poses a serious public health threat. This study aimed to investigate the feasibility of creating a coal dust suppressant using molasses, a byproduct of the sugar industry. We studied the effects of a molasses solution of varying concentrations (i.e., ranging from 0% (pure water) to 40%) on the moisture, bonding, and wind erosion properties of coal dust. Overall, the effectiveness of the molasses increased with their concentration, and it manifested itself in the following way: (1) the molasses improved the anti-evaporation ability of wet coal dust. For example, the evaporation mass of the coal dust wetted using a molasses solution decreased by 82.8%; (2) molasses effectively agglutinated coal dust; (3) molasses can effectively decrease the surface tension and increase the viscosity of the wetting solution. The surface tension of the molasses solution reached 41.37 mN/m and the viscosity increased to 6.79 mPa·s; (4) molasses can significantly suppress the wind erosion of deposited coal dust, with its wind erosion mass decreasing 99.1%; finally, (5) the effectiveness of molasses at suppressing coal dust was discussed at a molecular level. This study highlights the feasibility of a low-cost and environment-friendly dust suppressant in coal mines.