Application of animal fat-based biodiesel and glycerol for sustainable flotation of coking coal fines

The growing demand for environmentally sustainable flotation reagents has encouraged the development of renewable alternatives to conventional petroleum-based reagents used in coal beneficiation. In the present study, the animal fat-based biodiesel (AFBD) as a sustainable collector and its by-product glycerol (GLY) as a frother were utilized in the flotation of coking coal fines beneficiation. The coal sample with 29.85% ash and 47.90% fixed carbon required beneficiation prior to its metallurgical applications. The physicochemical characteristics of the coal and the synthesized flotation reagents were examined using XRD, SEM, petrographic analysis, FTIR, GC-MS, and contact angle measurements. Flotation experiments were designed using a Taguchi L18 orthogonal array, and the results were compared with those obtained using the conventional diesel-MIBC system. Under the best conditions, the AFBD-GLY reagent system produced a clean coal concentrate with a 62.22% yield, 14.08% ash, and 62.36% fixed carbon, indicating effective separation of combustible matter from mineral impurities. Flotation kinetic analysis further indicated that AFBD provided improved selectivity by reducing ash recovery compared to diesel, while achieving satisfactory combustible recovery. This study demonstrates that a novel combined application of AFBD and the transesterification by-product glycerol can replace the conventional diesel-MIBC system, providing sustainable and environmentally friendly flotation reagents for coking coal beneficiation.