General patterns of pollutant removal after blasting in blind headings

Abstract An essential condition for the safe execution of underground mining operations is the proper organization of auxiliary ventilation in blind headings. While numerous studies address specific technical solutions or field practices, the general regularities governing the removal of harmful impurities remain insufficiently explored. In particular, the role of flow structure and interactions between distinct aerodynamic zones within the heading is rarely analyzed from a fundamental perspective. This study focuses on identifying universal patterns in the unsteady dilution and removal of post-blast contaminants under forcing ventilation. A mathematical model of airflow in a blind heading was developed, incorporating impurity transport during blasting operations, and validated against published data from full-scale and numerical experiments. A series of parametric simulations across a range of airflow rates, ventilation duct setbacks, and heading cross-sections revealed that the decay of contaminant concentration in the face zone follows an exponential law. The key parameter determining the rate of concentration decrease was identified, and an approximating function was derived to express it as a function of airflow rate and duct setback. This relationship holds consistently for both average and peak concentrations and across different cross-sectional geometries of the heading. We show that ventilation efficiency, expressed via the decay rate of harmful gas concentrations, can be maintained by a compensatory increase in airflow when the duct is positioned farther from the face. The results are interpreted using a two-zone flow model, offering a generalized understanding of ventilation dynamics beyond site-specific conditions and contributing to a more universal framework for designing efficient ventilation schemes in blind headings.