Conventional and numerical models of blasting gas behaviour in auxiliary ventilation of mining headings

A study has been carried out in a coal heading, excavated by drilling and blasting in a deep underground mine located in Northern Spain (Hullera Vasco Leonesa S.A.), by measurements of blasting gases, CO and NO2, in three cross-sections of the heading located at 20, 30 and 40 m from the heading face.Mathematical models of gas dilution, according to the dilution time after blasting, have been developed. These models show the differences between the obtained values by application of these experimental models and the values of other mathematical model in common use.The mentioned differences indicate the need to obtain in each underground work its own dilution models of blasting gases. This need is more important when the mass of explosives, the cross sectional area of the heading and the conditions of the auxiliary ventilation keep away from the ones used in order to obtain the mathematical model in common use.4D models have been developed by Computational Fluid Dynamics (CFD) through software Ansys CFX 12.0. The CFD model results have been validated and compared to experimental models obtained in the measurement programmes.From these CFD models other dilution behaviour mathematical models of blasting gases can be developed for other cross sectional areas, other mass of explosives and other ventilation parameters.The experimental mathematical models and CFD models obtained allow us to analyse how the blasting gases behave and therefore to know in which conditions it is safe for the workers to return to a blasted area.

► A study was carried out in an underground coal heading, excavated by drilling and blasting.
► Measurements of blasting gases CO and NO2 in three cross-sections of the heading were collected.
► Gas dilution mathematical models were developed and validated by the experimental programmes.
► 4D CFD models were developed and validated by the experimental programmes.
► These models allow us to know in which conditions it is safe for the workers to return to a blasted area.