from the conferences organized by TANGER Ltd.
Fayalitic copper slag (CS) from the reverberatory furnaces is an abundant metallurgical by-product containing trace amounts of critical elements such as germanium (Ge). This study investigates the integration of bioleaching and chemical leaching approach to recover Ge combining the micro-organism of Bacillus subtilis pretreatment with selective oxalic acid leaching in the presence of Hydrogen peroxide (H2O2). The characterization of CS used XRF, XRD, and SEM-EDS confirmed that the slag is predominantly composed of fayalite (Fe2SiO4) and magnetite (Fe3O4) with Ge dispersed within the silicate matrix. Bioleaching effectively mobilized Ge subsequently oxalic acid and H2O2 leaching selectively dissolved Ge into solution while iron (Fe) precipitated as ferric hydroxide (Fe (OH)3). Kinetic leaching analysis revealed that Ge dissolution is diffusion-controlled with optimal Ge recovery of 50% achieved at 1.5 M oxalic acid over 30 minutes at fixed 25°C and 150rpm. After adding H2O2, Ge recovery reached 28%, indicating that the system reached equilibrium and further dissolution slowed down recovery. This combined method demonstrates an environmentally friendly and efficient strategy for Ge recovery. Further work should focus on optimizing the leaching conditions and developing scalable recovery methods to make the residues of Fe-Si-rich to enhance resource utilization of the material for sustainability and reduce environmental impacts of critical metals lost.
Keywords: Bioleaching; copper slag; germanium© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.