Controlled recirculation in Canadian underground potash mines

Abstract

Increasing energy costs and the need to conserve energy compounded with low mineral prices have prompted some Canadian mines to examine their energy-consuming operations and identify potential energy saving methods. Reusing or recirculating a fraction of ventilating airflow may make it possible for these mines to reduce heating costs. Such a study was conducted at Rocanville Division of Potash Corporation of Saskatchewan to determine the feasibility of controlled recirculation for reducing winter heating costs by reducing the intake airflows. This study was divided into two parts: the first involved taking measurements of mine contaminants in the return and intake airways, the second was monitoring air quality during a recirculation trial. Recirculation of air was created by opening an existing ventilation door located between the return and intake airways. Two shifts were continuously monitored in the return airways and the local recirculation experiment was carried out for five hours while a continuous miner was cutting. With the recirculation system in operation, a slight increase in temperature (1.00°C) was recorded between the intake and mixed intake. The overall quality of the exhaust air was found to be unchanged within the measurement limits despite the high percentage recirculation. A 5% increase in dustiness in the mixed intake was recorded. The results obtained from these studies indicate that controlled recirculation of return air is feasible. Some of the results from this work are illustrated and discussed.