EFFECT OF OXIDATION ON THE RATE OF AGGLOMERATION OF COAL WITH OIL

A promising method for cleaning coal involves suspending the finely gr ound material in water and selectively agglomerating the more hydropho bic and oleophilic components with oil or a hydrocarbon such as heptan e. In order to study the effect of coal surface properties and other p arameters on the rate of agglomeration, a number of agglomeration test s were conducted in which a batch of coal was agglomerated with either heptane or hexadecane, and the rate of change in the turbidity of the suspension was determined. Two types of bituminous coal were utilized , and the surface properties of each type were varied by exposing the ground materials to air at 150 degrees C for periods ranging from a fe w hours to 84 hr. Measurements made by means of FT-IR photoacoustic sp ectroscopy showed that the concentration of oxygen functional groups i ncreased with increasing oxidation time. Furthermore, the apparent rat e of agglomeration of either type of coal decreased with increasing ox idation time. Therefore, the rate of agglomeration depended on both th e rank of the coal and the extent of oxidation of the coal. The rate w as also found to depend on the type of agglomerant and its dosage. Whi le the rate tended to increase in direct proportion to agglomerant dos age, the rate of increase with respect to the dosage fell as the coal became more heavily oxidized.