Flotation of Non Coking Coal Using Plant Seed Derived Collector: Performance Evaluation and Kinetics Studies

Abstract

Coal beneficiation using flotation is a well-established technique for improving the quality of coal by enhancing combustible recovery. Traditional flotation relies mostly on petroleum-based collectors like diesel or kerosene, which are non-renewable. In response to the growing demand for sustainable and eco-friendly alternatives, this study investigates the flotation performance efficacy of biocompatible, plant-seed derived oil as non-coking coal collector. This oil, as a green collector for non-coking coal, was characterized using FTIR and GC-MS to identify the functional groups and their fatty acid composition, respectively. Laboratory scale flotation experiments on non coking coal (38% ash content) were conducted to assess the performance of the green collector in terms of combustible recovery, ash recovery and separation efficiency, and were compared with that of the conventional collector, diesel. MIBC was used as frother in both cases. Taguchi design of experiments was employed to optimize the flotation process parameters (collector and frother dosages, AFR) to evaluate the responses (combustible and ash recovery, separation efficiency). The plant seed based collector demonstrated better performance over conventional diesel, achieving a higher separation efficiency of 67.97%, combustible recovery of 83.56%, and a lower ash recovery of 15.59% at an optimized dosage of 4.6 Kg/t, along with 0.54 Kg/t MIBC frother and an airflow rate of 2.5 L/min. In contrast, the use of diesel at a higher dosage of 8.3 Kg/t, with 0.95 Kg/t MIBC and 1 L/min airflow, resulted in comparatively lower separation efficiency (64.34%), slightly reduced combustible recovery (81.91%), and higher ash recovery (17.57%), thereby highlighting the plant seed derived collector's enhanced selectivity and flotation performance. For flotation kinetics study, the ash and combustible recoveries were recorded at different flotation time intervals under optimal conditions for both the collectors and fitted to the first-order kinetic model 𝐑=𝐑∞(𝟏−𝐞−𝐊𝐭). The model provided two key parameters, ultimate recovery (R∞) and rate constant (K). With plant-seed derived oil as the collector, ash recovery exhibited R∞ and K values of 42.54 and 0.009, respectively, while combustible recovery showed values of 97.29 and 0.007. Conversely, when diesel was employed as the collector, ash recovery had R∞ and K values of 43.03 and 0.005, and combustible recovery had values of 94.72 and 0.004, respectively. The kinetics result indicates plant-seed derived oil is a more effective collector than diesel for maximizing combustible recovery, as evidenced by its significantly higher R∞ value for combustibles. This study highlights the potential of bio-derived collector as a viable, eco-friendly solution for cleaner coal processing and reduced environmental impact, aligning with current trends in sustainable practices.