Carbon mineralization using plagioclase feldspar-rich mine tailings: characterization and cation extraction

Abstract

The possibility to capture and store CO2 in mine tailings has gained significant traction as a viable climate mitigation technique. The mineralogy and chemistry of mine tailings can vary drastically depending on the type of mine and local geology. Tailings from Sibanye-Stillwater, a mine in Nye, Montana, USA that produces nickel, copper and platinum group metals (PGM), possess sufficient calcium and magnesium to store CO2. However, efficient CO2 storage is a difficult task due to the heterogeneous mineralogy of the tailings. This study involved using the Alternative AA Route to efficiently extract calcium and magnesium from the Sibanye-Stillwater tailings. At optimized conditions (45o oC, 30 min), about 39% of the Mg and 15% of the Ca in the tailings were extracted. While the Alternative AA Route proved successful in extracting phyllosilicate-bound magnesium, it was ineffective in extracting calcium from the tailings, which is mostly present in the form of plagioclase feldspar. Further studies aimed at targeting calcium extraction while maintaining or increasing magnesium extraction will be necessary to realize the full potential of CO2 storage in the Sibanye-Stillwater tailings.