An Overview of Prediction and Control of Air Flow in Acid-Generating Waste Rock Dumps

Air movement and associated oxygen transport through waste rock dumps has the potential to significantly enhance the rate of oxidation of pyrite-bearing material. While this is a desired outcome for most heap leach operations, airflow in waste rock storage facilities can result in significant increases in generation and acceleration of acid rock drainage. Hence, a good understanding of internal airflow through waste rock dumps is required to control ARD and minimise any associated liability. The principal mechanisms contributing to airflow and oxygen transport in a waste rock pile include: 1. diffusion; 2. advection due to a thermal gradient (chimney effect) and/or wind pressure gradients; and 3. advection due to barometric pumping. While diffusion is typically limited to a near-surface zone of a fe