Influence of the sorption properties of potash salts on the gas environment in dead-end mine workings

The results of gas-air surveys conducted at the mines of the Verkhnekamsk potassium-magnesium salt deposit indicate that the volume of gaseous impurities recorded in the main ventilation drifts is often significantly lower than in the working areas of dead-end workings. Many studies attribute the reduction of gas impurities along the ventilation airflow path in potash mines not only to the dilution of harmful impurities due to fresh air leakage from intake drifts but also to the neutralization of gases through chemical reactions with the potash rock mass. Previous laboratory studies have shown that sylvinite (NaCl + KCl) is capable of absorbing impurities of toxic and combustible gases. Based on these laboratory findings, the present study was conducted under real mining conditions, taking into account the dynamics of gas impurities in the underground atmosphere and the dilution effect caused by air leakage. As part of this study, measurements of combustible and toxic gas concentrations were conducted in productive seams of varying mineral composition at one of the mines of the Verkhnekamsk potassium-magnesium salt deposit to assess the influence of potash salt properties on the gas balance in long dead-end workings. An analysis was conducted to assess the extent to which the properties of the potash rock mass influence changes in the concentration of combustible and toxic gases in the workings along the ventilation airflow path. The collected air samples were analyzed under laboratory conditions. The concentration of combustible gases, carbon monoxide, and carbon dioxide in the collected air samples was determined using gas chromatography with the CHROMOS GX-1000 instrument. The contribution of gas neutralization and dilution due to leakage from the ventilation ducting to the reduction of combustible and toxic gases in the outgoing airflow from the working area was evaluated. The results of the conducted tests established that in long dead-end chambers of seam AB (100 m or more), the volume of gaseous impurities decreases along the length of the working from the dead end to the entry. The study accounted for factors that could influence the reduction of gas concentration in the working area.