Characterization of the effects of grain size to mine water quality and Acid Rock Drainage (ARD) production in Kinetic Testing

Rodrigo Embile Jr is representing MinSouth, from The University of Exeter

The quality of mine drainage from sulfide containing waste dumps is controlled by several factors and surface area (grain size) exposed to weathering conditions is important. However, the textural variation may control the main driving mechanisms for an acid generating or neutralizing reactions. Depending on their rates and intrinsic properties, leachate chemistry for a certain grain size can be characterized through different types of tests and analysis. Kinetic test using humidity columns is performed on five different grain size ranges of waste rocks. Water leachate quality is analysed on a weekly basis for their pH, alkalinity, conductivity, anions, cations and dissolved metal concentrations. Results showed that finer grains produced near neutral to neutral pH and higher sulfate production rates unlike for coarser grains. This indicates that the rate of sulphide oxidation and neutralization may be only partly controlled by grain size as well as a number of interrelated factors.