- By:
- Gregorich, Nicholas E; Kalla, Joseph H; Irwin, Mary H; Pethe, Saurabh Prakash ; Abbas, Mustafa ; Coin, Zachary C; Paranthaman, Mariappan ; Uddin, Md Majbah ; Dangwal, Shailesh Singh ; Bhave, Ramesh R; Islam, Syed Z
- Journal Name:
- Carbon Capture Science & Technology
- Page Number:
- 100629
- Volume:
- 19
- Publication Date:
- June 8, 2026
- View DOI Listing:
- https://doi.org/10.1016/j.ccst.2026.100629
Abstract
Ocean alkalinity enhancement (OAE) has emerged as a promising strategy to mitigate ocean acidification and reduce global warming. Traditional metal (e.g., critical materials) mining industries release alkaline waste via mining tailings with high concentrations (99.2%) of calcium and magnesium oxide (CaO, MgO). Incorporating mining waste into OAE processes is less energy intensive than processes relying on calcination of limestone for CaO production. The solubility limit of mining waste in American Society for Testing and Materials (ASTM) seawater is 75 mgL-1, which can sequester 118 mg of carbon dioxide (CO2). Changes in pH, total alkalinity, and total inorganic carbon were analyzed to confirm the successful addition of alkaline mining waste without the formation of secondary precipitation. This study proposes a new OAE strategy where a facility is developed nearby ocean waters that mixes alkaline waste with seawater. Subsequently, the seawater is met with previously captured, pure CO2 to bring the pH back to 8.2 and eliminate the risks of pH shock and secondary precipitation. Technoeconomic analysis estimated an energy requirement of 1.4 GJ per ton of CO2 removal that resulted in a processing cost of $266 per ton of CO2 sequestered. Results from this study underscore the potential for utilizing mining waste in OAE processes and provide a pathway for practical deployment.
