The extent of toxic metal contamination in waterbodies near mine tailings is severe, especially in countries like South Africa, where there has been uncontrolled release of mining operation and tailings run-off waters. Mining discharge waters contain high levels of metalloids and metals like arsenic and lead, and sources of high acidity such as sulfuric acid. Solving the water pollution problem consistently associated with mining activities is an important focus of many mining countries. In this work, a new strategy is proposed for toxic metal removal from mining waste waters. The strategy involves immobilization of toxic metals through precipitation and co-precipitation from solution with the addition of various sources of alkalinity, anions, and basicity from fly ash, seawater, high concentration CO<sub>2</sub>, and bases. This strategy has the added benefit of carbon dioxide fixation, positively contributing to greenhouse gas reduction. Simulated mine tailings run-off waters were treated to show overall feasibility and CO<sub>2 </sub>emission reduction potential through geochemical modeling and experimental work. We show direct evidence of co-precipitated solids, indicating effective immobilization of toxic metals. Detailed cost-analysis of different treatment options, and finding appropriate cost minimizing reagents were done. Significant insights are obtained for the waste water treatment of mine tailings of different composition and origin, based on experimental and geochemical modeling analyses.

Mineral precipitation for simultaneous toxic metal uptake from mining run-off and carbon dioxide fixation for reduction of greenhouse gases

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.