Development and Underlying Mechanisms of a Biomass-Based Composite System for Dust Suppression and Explosion Mitigation of Coal Dust Generated by Coal and Gas Outbursts

Fine coal dust generated by coal and gas outbursts is difficult to wet, readily resuspended, and capable of contributing to secondary explosions during emergency rescue. A biomass-based composite comprising pectin extracted from citrus residues, sodium alginate, sodium phytate, rhamnolipid, sodium carboxymethyl cellulose, and citric acid was developed and optimized using a Box–Behnken design. The resulting local optimum within the investigated design space (OPT; 2.15% total active components) exhibited an equilibrium surface tension of 36.2 ± 0.72 mN·m−1 and a mean loose-dust wetting time of 56.6 ± 13.7 s, compared with 75.4 ± 13.1 s for the practically applicable 0.80% SDBS/APAM reference. An additional 2.15% SDBS/APAM formulation retained a similar equilibrium surface tension (34.2 mN·m−1) but exhibited a markedly elevated apparent viscosity (587.5 mPa·s), showing that equal-solids matching produced a substantially different rheological condition. Under stepwise exposure to 3–15 m·s−1, the fully dried OPT layer showed only 1.2% cumulative wind erosion after 35 min; an independent 15 m·s−1, 30 min validation using fresh specimens yielded 2.3 ± 0.3% mass loss. In 20 L explosion tests, OPT reduced the maximum explosion pressure from 0.709 ± 0.017 to 0.609 ± 0.016 MPa and the maximum pressure-rise rate from 11.39 ± 0.45 to 3.90 ± 0.25 MPa·s−1. Because the electronic igniter energy was not independently calibrated, these explosion parameters and the apparent deflagration index are interpreted only as relative measures under the present apparatus conditions and are not used for formal St-class assignment. FESEM, EDS, and representative-spectrum Raman analyses were consistent with particle aggregation, surface retention of Na/P-containing material, and altered post-explosion carbon-framework evolution. These observations support a proposed multistage pathway involving pre-ignition particle connection and possible condensed-phase participation, while the specific phosphorus-containing products and individual component contributions remain unresolved. The study therefore provides an integrated evaluation of field-collected outburst coal dust from wetting and dry-state stabilization to confined-vessel explosion mitigation.