(632g) Ultrasound-Assisted Leaching of Magnesium from Nickel Mine Tailing: Enhancing Extraction for CO2 Mineralization

Mine tailings rich in magnesium (Mg) offer a sustainable feedstock for CO₂ mineralization due to the formation of stable carbonates. Optimizing Mg extraction enhances overall process reactivity, enabling effective carbon capture while repurposing mining waste. The efficient extraction of Mg is a crucial step in the development of an efficient CO₂ mineralization process for nickel mine tailings. This study investigates the acceleration of Mg leaching using a probe-type ultrasound processor, aiming to maximize Mg recovery and produce a reactive Mg-rich solution for CO₂ sequestration. The effects of two acid agents—hydrochloric acid (HCl) and citric acid—at different concentrations were examined to determine the optimal leaching conditions. Additionally, the influence of processing time on Mg extraction efficiency was investigated.

To further enhance leaching performance, the impact of combined heat pretreatment of nickel mine tailing with ultrasound extraction was explored. Thermal activation was used to enhance mineral dissolution by transforming its crystalline structure into more reactive amorphous or dehydroxylated phases. The combined influence of ultrasound-assisted leaching and heat pretreatment was systematically analyzed to identify conditions that promote rapid and efficient Mg extraction.

For non-pretreated samples, the results indicated that ultrasound-assisted HCl leaching improved Mg and Ca extraction by up to 35% and 14%, respectively. For citric acid, the leaching improvement with ultrasound was up to 33% for Mg and 29% for Ca. In addition, it was observed that a higher solid-to-liquid ratio resulted in lower extraction efficiency for both metals under study. In contrast, thermal pretreatment of feedstock significantly enhanced extraction efficiency, with improvements exceeding 100% for a 0.5M HCl solution.

These findings provide valuable insights into optimizing leaching strategies for CO₂ mineralization applications in general, and for Nickel mine tailing in particular. Furthermore, the study highlights the potential of ultrasound-assisted acid leaching as an effective method for accelerating Mg dissolution from nickel mine tailings.