Numerous fine coal processing technologies like froth flotation, enhanced gravity separation exist today, but their insularity have led to the adoption of oil agglomeration as a retrieval technique. In the present study, coal fines were recovered by the oil agglomerating process with the agglomerating oil as a waste vegetable oil - waste mustard oil. The effect of pulp density, oil dosage and agglomeration time were analysed on the responses - organic matter recovery (% OMR) and ash rejection (% AR). The responses were optimized using three-level Box Behnken experimental design in conjunction with the Response Surface Methodology. The resulting conditions were 99.69% for % OMR and 62.56% for % AR, showcasing that waste mustard oil has good agglomerating properties, despite of the heat treatment undergone by it during frying. Optimization studies were also performed by minimizing the oil dosage to countervail the poor economics of the oil agglomeration process. The observed conditions were investigated as 79.21% for % OMR and 65.41% for % AR obtained at an oil dosage of 8.39%. The comparative examination of these results with the contemporary studies of different oil types proved that waste mustard oil is a much better bridging liquid than the currently available oils. (C) 2019 Elsevier B.V. All rights reserved.