“…Second group includes optimization and/or experimental design studies undertaken for determination of most important parameter and optimum values of process parameters to obtain maximum performance and comparison of influence of each parameter [12][13][14][15][16][17]. Third group includes studies undertaken for individual effects of one or more parameters or various pretreatments on oil agglomeration of coal [2,5,6,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Although various parameters such as solid ratio, oil dosage, oil type, agglomeration time, stirring speed, coal type, coal particle size, pH of the media, washing water amount, and salt content have been investigated in above mentioned three groups of studies, oil dosage, solid ratio, agglomeration time and stirring speed had been the most widely investigated parameters.…”