Preparation and effect analysis of cedar sawdust-based super absorbent dust suppressant material

Massive coal debris and dust are generated in the process of coal production and transportation, greatly affecting coal mine working environment and local residents. This study is aimed at promoting the dust suppression efficiency of dust suppressors and improving the working space and surrounding environment following the principle of waste reuse. Specifically, a new type of green superabsorbent dust suppressor (AA-DWF-PAM/GD) was prepared by treating the raw material, i.e., China fir sawdust, with solutions such as NaOH and Na₂SO₃ through microwave-assisted in-situ synthesis. The following findings were obtained. The microscopic morphology, reaction mechanism, thermal stability and water absorption performance of AA-SW-PAM/GD were investigated by means of SEM, FTIR, TG-DTG and swelling kinetics experiments. The results show that AA-SW-PAM/GD presents a network structure and boasts high stability. DWF reacts well with acrylic acid (AA) and polyacrylamide (PAM), and no activity damage occurs before 73 ℃. Besides, the dust suppressor has the highest water absorption rate of 325 times, and its highest salt water absorption rate is about 100 when the solubility of NaCl, MgCl₂ and CaCl₂ salt solutions is 1%. In the dust suppression performance test, AA-DWF-PAM/GD reaches a dust suppression rate of about 90% when the airflow velocity is 14 m/s. After AA-DWF-PAM/GD is mixed with coal for combustion, the heat release rate is increased by 4.53 kW/m², and the combustion time is prolonged by about 15 s. That is, after being sprayed during its use, AA-DWF-PAM/GD will not pose a negative impact on the calorific value of coal. According to the results of molecular dynamics simulation, AA-DWF-PAM/GD primarily acts on the coal-water interface, raising the thickness of the coal-water interface to 28×10⁻⁶ mm (13-41×10⁻⁶ mm), enhancing the diffusion of water molecules on the coal surface and attracting water molecules to migrate toward the coal seam. Moreover, after its addition, the self-diffusion coefficient (D) of water molecules grows by 4.3×10⁻⁹ m²/s, which means that the wettability of the coal seam surface is promoted. Overall, considering its low cost, environmental friendliness and remarkable dust suppression performance, AA-DWF-PAM/GD proposed in this study is a promising dust suppressor that can be widely used in coal mines.