Effect of various bridging liquids on coal fines agglomeration performance

Oil agglomeration is a surface property based on the differences in the surface properties of the organic and inorganic constituents of coal. A bituminous coal was agglomerated using kerosene, diesel oil, Kirkuk Crude Petroleum. extract fractions (obtained from Soxhlet extraction)-kerosene or toluene mixtures and toluene. The amounts of bridging oils were varied from 5% to 30% of the initial coal loading. Centrifugal float-sink separations of the coal in dense media were conducted and the results of their grade recovery performances were compared with those of the agglomeration of the particles. Factors affecting the agglomeration performance, such as the amount of bridging oils and washing water, type of bridging oil, solid content of the slurry and finer particles, were determined. The relationship between the agglomerate sizes and their ash content was also determined. Higher recovery values (> 95%) were obtained from the agglomeration tests. Extract-oil fraction of the coal extract at various ratios in kerosene decreased the agglomeration recovery from 98.99% to 88.44%. A sharp decrease (from 90.52% to 56.01%) in the recovery was observed for asphaltane fraction of the coal extract in toluene. Increase in finer particle portion in the bulk solids decreased the grade values of the final product. (C) 2001 Elsevier Science B.V. All rights reserved.