Novel oxygen-enrichment method using annular air curtain for single-head roadway of plateau mine

The low-oxygen environment restricts the exploitation of mineral resources on plateaus and affects miner’s safety. This paper proposes an oxygen-enrichment method using an annular air curtain. Through numerical simulation and experiments, it was confirmed that the proposed method improves the breathing environment in the single-head roadway of a plateau mine. Computational fluid dynamics (CFD) was used to investigate the oxygen-enriching effect and oxygen spatial distribution regularities after using the proposed oxygen-enrichment method in the single-head roadway of a plateau mine. The reliability of the CFD model was confirmed by experiment. Orthogonal testing was conducted to investigate the influence degree and optimal level combination of factors influencing oxygen enrichment. The results demonstrate that the annular air curtain effectively prevented oxygen loss, thus forming a local oxygen-rich space and improving the effective utilization rate of oxygen. Oxygen supply concentration and velocity are positively correlated with the oronasal oxygen mass fraction through a linear function, while the air curtain outlet wind velocity is negatively correlated with the oronasal oxygen mass fraction through a linear function. The annular air curtain diameter and oronasal oxygen mass fraction do not have an obvious functional relationship. When the annular air curtain diameter was greater than 0.9 m, the oronasal oxygen mass fraction was stable at approximately 25.30%. The influencing factors of the novel oxygen-enrichment method are, in descending order, as follows: oxygen supply concentration, annular air curtain diameter, air curtain outlet wind velocity, and oxygen supply velocity. The optimal level combination is oxygen supply concentration of 100%, oxygen supply velocity of 11 m/s, air curtain outlet wind velocity of 1.5 m/s, and annular air curtain diameter of 0.9 m.