High-efficiency ventilator plants for artificial ventilation of deep open-cut mines

Abstract

Ventilation of open-cut mines is now an important problem which has arisen in recent years owing to the continual development and improvement of open-cut mining. Some open-cut mines are now 500 to 700 m deep and are getting 15 to 20 m deeper every year. In the future the rate of deepening may reach 50 m per year and the total depth exceed the 700-m mark. The increased depths of the mines, the use of powerful techniques, and the increasing volume of mining operations are causing the atmospheres of these mines to become filled with large amounts of dusts, gases, and aerosols. This spoils the conditions for natural air exchange and often leads to situations in which health hazards arise. Work must then be stopped, leading to economic disadvantages to the mining undertakings. Such situations can be avoided in most cases only by artificial ventilation of individual stagnant zones and of open-cut mines as a whole. It is found in practice that the most effective pipeless method of ventilating open-cut mines is by free or semibounded turbulent air jets, based on the theory of free submerged jets. The effectiveness of this method depends directly on the range of the jetmore » created by the ventilator plant and on the rate of air flow in the ventilated cross section: the greater these parameters, the less is the time of operation of the ventilator plant needed to normalize the atmospheric conditions in the mine. By the range of the jet we mean the distance from the initial cross section (the point of emergence of the air current from the ventilator) to the ventilated cross section in which the mean velocity of the air just does not exceed the value fixed by the ventilation conditions.« less