Актуальность исследования обусловлена необходимостью улучшениясистемы вентиляции тупиковых выработок, сокращения трудозатрат на ихвентиляцию и ускорения выполнения основных операций по проходке выработок. Цель: определение оптимального расстояния от конца трубопровода до груди забоя тупиковой выработки с точки зрения эффективности проветривания тупиковой подготовительной выработки. Объект: система вентиляции тупиковой подготовительной выработки. Методы:многопараметрическоетрехмерное численное моделирование на основе методов вычислительной гидродинамики. Приведены результаты трехмерного численного моделирования проветривания тупиковой подготовительной выработки от выделившихся в результате взрывных работ ядовитых газов. Варьируемыми параметрами модели являются: начальная концентрация и распределение вредных примесей в тупиковой выработке после проведения взрывных работ, расстояние от конца нагнетательного трубопровода до тупикового забоя, поперечное сечение тупиковой выработки, а также расход свежего воздуха, поступающего через трубопровод. Получена расчетная формула для определения объема зоны смешения.Показано, что время проветривания тупиковой выработки не зависит от длины зоны отброса газов, а зависит от начальной средней концентрации ядовитых газов в зоне смешения.Получены значения безразмерного коэффициента эффективности проветривания Kтупиковой выработки, или коэффициента турбулентной диффузии В.Н. Воронина, в зависимости от варьируемых параметров. Показано, что коэффициент K не зависит от величины входящего расхода свежего воздуха, а зависит только от геометрических параметров системы вентиляции тупиковой выработки и принимает постоянное значение для данной конфигурации системы вентиляции.Показано, что существует оптимальное расстояние от конца трубопровода до забоя, при котором происходит наиболее эффективный вынос вредных примесей.

The paper presents the results of the mathematical modeling of the conditions for ventilating extended blind dead end stope chamber-like mine workings of large cross-section, which are formed by expanding the preparatory rifled mine working when loading and hauling machines with an internal combustion engine are operating in them. The experience of using CFD-modeling in solving problems of ventilation of such mine workings is analyzed. Numerical dependences of the change in the average concentration of exhaust gases at the workplace of the load-haul-dump machine operator on the operating time of equipment with an internal combustion engine in the stope area of the chamber were obtained. These dependencies allowed to determine the coefficient of efficiency of ventilation of dead-end stope chamber-like mine workings of large cross-section when operating equipment with an internal combustion engine in them. It was found that the ventilation efficiency coefficient can be taken equal to one both in the case of an increase in the concentration, and in the case of its decrease. The conclusion is made about the same regularities in the processes of accumulation and removal of harmful impurities in the dead-end mine working. Using a parameterized model, expressions were obtained for determining maximum operating time of the machine with an internal combustion engine for unloading ore from the stope area without exceeding maximum permissible concentration of the exhaust gases. An expression is also presented for calculating the minimum ventilation time of the chamber after the vehicle leaves and before its re-entry into the chamber. Made conclusions and obtained dependencies will allow to ensure safe working conditions for the miners in the extended dead-end stope chamber-like mine workings of large cross-section.

The air flow dynamics in a vertical mine shaft under conditions of mixed convection is theoretically studied using 3D modeling in ANSYS. The average heat-transfer coefficients are obtained at the air–lining interface depending on air–lining temperature difference and on the average air flow velocity. The threshold velocities of air flow are determined at various air–lining temperature differences. At the air flow velocities higher than the threshold, the engineering designs can neglect the influence of the heat–gravitational forces and use the formula of heat transfer in induced convection. When the air velocity is lower than the threshold, the heat-transfer coefficient should be adjusted with respects to the natural convection effect. The authors offer an empirical formula for calculating the average dimensionless heat transfer coefficient in case of prevailing natural convection.

A theoretical study of the formation of water build-up, or water blanketing, and its influence on the ventilation of mine upcast shafts was carried out. Two scenarios for droplet moisture accumulation in the shaft were considered: condensation from saturated air rising up the shaft and groundwater inflows through the leaky shaft lining. Analytical dependencies of the pressure drop due to the influence of water build-up versus the outgoing air flow velocity and the height of the groundwater source were obtained, taking into account the fractional composition of the droplet moisture. Practical arrangements are proposed to reduce the influence of the effect of water build-up in upcast shafts in the case of groundwater inflows through the leaky shaft lining.

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.