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Humidity cell testing of mine wastes under a CO2 supplemented atmosphere

Savage, Rhys 2023. Humidity cell testing of mine wastes under a CO2 supplemented atmosphere. PhD Thesis, Cardiff University.
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This doctoral research provides novel insights into the potential impact of an enhanced CO2 atmosphere on the weathering of sulfidic mining wastes. This research project was undertaken with the overarching purpose of assessing the potential implications of enhanced CO2 concentrations on mine waste geochemical development and acid rock drainage (ARD) classification and prediction. Multiple studies have outlined seasonal and temporal variations in pore gas compositions within sulfidic mine waste storage facilities. To date no standardised kinetic or static characterisation tests have been developed to assess such conditions. Within this study a standardised kinetic leaching test method, commonly used within the mining industry, is modified with the purpose of assessing the drainage quality development and ARD onset potential of waste materials exposed to elevated CO2 atmospheres. A 60-week modified humidity cell test (HCT) protocol was undertaken to simulate a waste drainage environment enriched with 10% CO2. Two sets of experiments were performed using wastes from distinct mine sites to test the robustness of the modified method. HCT cell sets were caried out at variable testing conditions to develop a more site-specific assessment of drainage quality prediction. This study demonstrated that the introduction of an enhanced CO2 atmosphere within the aeration system of a standard ASTM D5744 humidity cell test leads to variable weekly leaching characteristics. Key predictive parameters such as pH, sulfate, dissolved carbon species and metal leaching rates were shown to vary widely dependent on both the aeration system and temperature conditions. The importance of this study stretches beyond traditional ARD characterisation and prediction, with silicate rich sulfidic waste materials viewed as a potential feedstock for large scale carbon dioxide removal technologies. The application of the findings presented within this study should aid in the environmental regulation of large-scale carbon mineralisation and enhanced weathering (EW) projects.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: 1). Humidity cell test (HCT) 2). Carbon dioxide removal (CDR) 3). Kinetic Testing 4). Acid Rock Drainage (ARD) 5). Geochemistry 6). Enhanced rock weathering (ERW)
Date of First Compliant Deposit: 26 February 2024
Last Modified: 27 Feb 2024 10:21

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