Development of the Activities for Explosive Gases Removal from the Worked-out Area in Case of Potash Mine Flooding
The greatest danger for potash and salt mines is sudden rushes into the mine workings of the over-saline water, which is fresh or low salt brine. The main reason for the rush of the over-saline water into the underground area is insufficient capacity of the water-blocking ceiling (thickness) with the adopted mining parameters. Under current conditions, the rush of the water-blocking thickness and entry of the brines into a potash or salt mine are usually irreversible. Thus, the flooding of the mine in most cases leads to its end, loss of mineral reserves and various environmental problems. The latest period of potash mine flooding is considered, when the brines entering through the water-blocking thickness into the mine workings cut off the aerodynamic connections between the mine ventilation network and the atmosphere. In this case, the process of flooding of the mine is accompanied by the dissolution of rocks and the intense release of combustible and explosive gases into the worked-out area. The mathematical model of the air-gas mixture removal from the mine flood-free area using the pipeline system was developed. As a result of the simulation, it was shown that the influence of the resistance of the piping system is quite small and does not ensure significant resistance to the influx of brine into the worked-out area. Maximum flow rate of gas-air mixture at the outlet of the pipeline, and the content of combustible gases in the mixture depend on the option of draining-out of gases. The concentration of combustible gases in the outgoing stream will be increasing, and at a certain moment will exceed their maximum allowable content. In this regard, application of mixing chamber for diluting air-gas mixture emanating to the surface of the mine up to the maximum permissible concentrations of combustible and explosive gases using a forced draft source or due to ejection effect is proposed in the article.