Greg Galecki

Parametric Evaluation of Coal Comminution by Waterjets

In this study, comminution of coal with waterjets was performed to determine the factors that influence the particle size reduction. To carry out these experiments, a bituminous coal sample with an ash value of 31% was exposed to waterjet action within a conventional abrasive cutting head coupled with a specially designed cavitation chamber. Original coal feed of 371 µm volume mean diameter and its subsamples of 59, 172, 323, and 527 µm were used to investigate the effect of pressure on particle size reduction. For the purpose of this study, the comminution system was operated at 69, 138, 207, and 276 MPa. Physical properties such as particle size distribution and volume mean diameter were used for evaluation of the efficiency of comminution. Initial feed size was found as a dominant factor affecting the degree of size reduction. The increase in the cavitation system operating pressure resulted in finer products. Scanning electron microscopy studies of particle shape and morphology indicated transition from flaky to round and blocky particle shapes as a result of pressure increase. Severe clay dispersion was associated with all test conditions.

New Method of Coal Comminution to Ultrafine Size

Research into the use of coal for power generation has become more important to deliver next-generation solutions for advanced coal cleaning technologies required by near-zero emissions. Comminution of coal with waterjets to ultrafine particle size offers a new and promising method for producing coal-water fuel (CWF), which is a replacement for power generation products. In this paper the results of coal comminution in a waterjet-based mill are presented for the range of pressures up to 276 MPa using four groups of feed size ranging from minus 850 micrometers to less than 106 micrometers. The focus of studies was on particle size reduction and distribution. The results presented in this paper are part of ongoing studies of coal-water fuel optimization for power generation.