Fungal Leaching of Iron (Fe), Zinc (Zn), and Copper (Cu) in Copper Ore Waste from Ikalamavony, Madagascar, by Aspergillus sp.

The recovery of waste has become a global concern due to the economy's shift towards a circular economy, which includes the recycling of mining waste. This study aims to highlight the ability of the fungus Aspergillus to dissolve metals as iron, zinc, and copper from Ikalamavony ore waste through the bioleaching process for their recovery. The waste was subjected to granulometric analysis to classify the grains by weight and size, and the metal content was analyzed using Flame Atomic Absorption Spectrophotometry (FAAS). Bioleaching was conducted in two stages: first, the fungi were cultured on Sabouraud agar or broth medium at 28°C for 7 days, then the produced organic acids were recovered and the waste was placed in these acids. The optimization of certain parameters as particle size, sucrose content, medium volume, strain incubation time and bioleaching time was considered. The FAAS analysis results indicated that the waste contained an average of 5.35% Fe, 0.05% Zn, and 18.14% Cu. The optimum parameters obtained for each metal were as follows: for particle size, Fe and Zn: 125 µm; Cu: 200 µm; for sucrose content, Fe: 7.5 g and Zn, Cu: 12.5 g; for the volume of culture medium, Fe, Zn, Cu: 150 ml. The incubation time for the strains was 7 days. With these optimizations, the extracted metals were 73.89% Cu, 56.77% Zn, and 7.89% Fe for a leaching time of 15 days. These results confirm that bioleaching using Aspergillus sp. is an effective technique for the extraction and recovery of copper and zinc from ore waste.