Humidity Cell Investigation of Particle Size Effects on Weather Rates of Mine Waste Rock from the Antamina Mine, Peru. Yu, Emily
A laboratory humidity cell experiment was performed on marble diopside waste rock from the Antamina Mine of Peru, one of the world’s largest operating copper-zinc mines, in order to study the effects of particle size on weathering rates. There is currently little understanding of the geochemical characteristics of neutral drainage systems, and further knowledge is necessary to improve waste rock management techniques at mines hosted in rock with high neutralization capacity. Grain sizes less than 0.053 to 9.50 mm were separated into individual cells and seven weeks of leachate were collected then analyzed by ICP-OES for elements of concern. Results suggest that the finer the particle size, the higher the alkalinity and release rates of calcium, sulphur, molybdenum, magnesium, and manganese. This trend was especially apparent in the results of magnesium and manganese, where, unlike all other samples, the release rates in the finest grained sample increased over time. Concentrations of copper, chromium, nickel, and iron were determined to be below the detection limit of this analysis. The saturation indices of calcite were found to be above the saturation level in two samples. The continuation of this experiment will further characterize trends in particle size versus weathering rates. Additional parameters should be analyzed in the leachate to increase understanding of neutral drainage.
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