ABSTRACT
Numerical simulations of acid rock drainage production in the mine rock piles at the Questa Mine were performed to (i) identify the main processes responsible for the observed present-day conditions, such as temperature and oxygen, and (ii) provide an estimate of the significance of gas phase humidity transfer on the water balance of the pile. Numerical simulations show that the mine rock pile geometry on mountain slopes favors strong thermal air convection which results in evaporation of pore water leading to a reduction in the moisture content of the mine rock. Conceptual simulations indicated that “air drying” could be a significant component of the water balance for the mine rock pile. Numerical simulations considering benches also indicated significant redistribution of water vapor with vaporization of pore moisture in the lower portion of the pile and condensation in its upper portion. However, water balance calculations indicated that the net vapor loss from the entire rock pile is relatively small, accounting for only about 2 % of net infiltration.
