Comprehensive study of process parameters affecting oil agglomeration using vegetable oils

► Response of Assam coal to oil agglomeration has been investigated. ► Both edible and non-edible vegetable oils are equally good as agglomerants. ► Anionic surfactant usage did not improve the agglomerate yield. ► Use of sea water improves the coal recovery by oil agglomeration. Spherical agglomeration is a size enlargement process in which the disperse medium is held together in aggregates by liquid bridges of an immiscible agglomerating agent in the dispersion medium in general, an aqueous environment. Extensive studies on the process have shown that the process is affected by a number of process parameters. In the present paper, a large number of process parameters such as agitation speed, oil dosage, agglomeration time, coal particle size, slurry pulp density, pH and temperature of the dispersion medium, oil type, surfactant (anionic) use, and sea water usage as pulping medium. affecting the oil agglomeration of Indian bituminous coal procured from North-Eastern region of the country were investigated. Initially, the process parameters were optimized for maximum coal recovery with significant ash rejections. Subsequent experiments to study the effect of surfactant, oil type and sea water usage as pulping medium were performed under the optimized conditions. All the experiments were performed under batch mode of operation. The coal–oil agglomerates were recovered by screening using a standard test sieve whose pore size was same as the maximum size of feed coal particle. The overall agglomeration performance was studied in terms of efficiency index which took into account both combustible recovery and ash rejection, the two important process estimates of the agglomeration process. The experimental results showed that the Indian bituminous coal used in the study was quite receptive to oil agglomeration process and significant recovery of coal fines with considerable ash rejections was possible through this clean coal technology.