Design and Experiments of the Extraction of Critical Elements and Rare Earth Elements from Biotite-Rich Mine Tailings

The increasing demand for critical elements, including rare earth elements (REEs), has created the need for alternative and sustainable resource sources. Mine tailings represent a potentially valuable secondary resource due to the presence of economically important elements that remain after primary mineral processing. This thesis investigates the controlled dissolution of biotite-rich mine tailings to promote the release of selected critical elements and REEs, while limiting the dissolution of REE-bearing minerals such as monazite. The study includes the characterization of the tailings using mineralogical and chemical analytical techniques to identify the distribution and occurrence of elements. Dissolution experiments were carried out using citric acid under controlled pH and temperature conditions to evaluate and regulate the release of critical elements and REEs into solution. The influence of experimental parameters, including pH and temperature, was assessed through the analysis of liquid samples by inductively coupled plasma mass spectrometry (ICP-MS). The obtained results provide insights into the dissolution kinetics of the investigated elements and their extraction efficiencies from biotite-rich mine tailings. The findings provide insights into the potential of biotite-rich mine tailings as a secondary source of critical elements and REEs and highlight the importance of controlling pH and temperature to regulate mineral dissolution and element release.