As a fundamental energy resource, coal is pivotal to the national economic progression and the energy lifeline of China (Guo et al., 2020; Wang et al., 2020). However, in tandem with the rapid economic growth, the demand and extraction volumes for coal have burgeoned (Wang et al., 2020). In the year 2022, open-pit coal mines accounted for 22% of the nation's coal production capacity. Nonetheless, owing to the open-air mining environment, such operations precipitate substantial dust pollution (Luo et al., 2016). To address this issue, open-pit mines conventionally resort to dust suppression techniques such as water spraying, foam dust removal, and the application of chemical dust suppressants (Liu et al., 2021; Dong et al., 2023; Anlimah et al., 2023). While these dust control technologies deliver moderate amelioration, they are accompanied by the following drawbacks: water spraying not only squanders significant quantities of freshwater resources but also has its dust suppression efficacy contingent on meteorological conditions; foam dust removal introduces new chemical pollutants, engendering secondary contamination(Zhang et al., 2021); and chemical dust suppressants, with their inherent toxicity, irritancy, and corrosivity, coupled with poor degradability, fall short of meeting the standards for green mining practices(Wang et al., 2021).
Microbial dust suppressants, developed based on the technology of Microbially Induced Carbonate Precipitation (MICP), represent a green, non-polluting, and biodegradable solution for dust suppression (DeJong et al., 2006; Zhao et al., 2023; Yu et al., 2022). The underlying principle involves the secretion of urease by microbes, leading to the hydrolysis of urea under the catalytic action of urease, resulting in the formation of carbonate ions. These ions react with calcium ions to produce calcium carbonate precipitates, which bind coal dust particles and ultimately form a calcium carbonate-coal dust solid mass, achieving the purpose of dust suppression (Geng et al., 2023; Liu et al., 2022; Ji et al., 2022; Peng et al., 2018). Due to the mild and environmentally friendly nature of the MICP technology, it has been extensively studied both domestically and internationally. For instance, Wang et al. reported a 40.72% increase in dust suppression efficiency using a suppressant made from Bacillus subtilis sprayed on anthracite coal dust, compared to traditional methods. Farashahi et al. observed an 87% increase in dust stability and about 40% lower airborne anthracite dust concentration when spraying a microbial dust suppressant containing Bacillus subtilis on lignite coal dust, compared to control samples (dry coal powder). Zhang et al. demonstrated improved wettability and best dust suppression efficiency for 40–80 mesh bituminous coal dust using a suppressant made from B.X4 bacteria, 1.61 times more effective than for 120–200 mesh bituminous coal dust. These studies indicate the effectiveness of microbial dust suppression technology in consolidating coal dust. However, due to most scholars focusing on single coal types, it is challenging to determine the consolidating effect of microbial dust suppressants on coal dust of varying metamorphic grades under identical conditions.
Building on this foundation, the present study investigates the consolidation effects and dust suppression mechanisms of microbial dust suppressants on coal dust with varying degrees of metamorphism, including bituminous, anthracite, and lignite coals. By examining the differential physical properties of coal dust based on metamorphic grade, the anti-erosive properties, and consolidation characteristics post-treatment with microbial dust suppressants, this research clarifies the efficacy and mechanisms of microbial dust suppression across different coal metamorphic stages. This study not only contributes to the advancement of microbial dust suppression technology but also lays a foundational framework for its application in field settings.