Tailings as a Source for Generating valuable Magnesium and Calcium Carbonates by Leaching and Carbonization

Mining produces a lot of disposable mineral waste after the ore has been removed. This waste with added CO2 can be used as a feedstock for carbonate production. The advantage of this production process would be the recycling of a waste product with additional carbon capture. However, the processing challenge is a feed with a fluctuating composition of the mining waste, which makes classical engineering and control with fixed process parameters difficult. For characterization, model particles and tailings are studied for their behavior with fluctuating acid and mass concentrations as a function of leaching time. The results confirm the possibility of leaching calcium (max 7g/L) and magnesium (max 0.7 g/L) using hydrochloric acid. The amount varies depending on the particle, concentration and pH. Mathematically, the leaching over time can be described by a power law, which is applied to both investigated cases for the leaching of calcium and magnesium ions. Finally, a pH shift process is used to precipitate solid CaCO3 from the ion-enriched solution obtained, thus demonstrating the successful production of CaCO3 and carbon capture from mine waste.