The conventional technologies used in industrial operations to achieve fine size separations at 150 mum and below are inefficient. To obtain precise fine size separations, the state of the art fine particle sizing technologies investigated in this study include the newly developed Pansep screen as well as a new design cyclone (gMax(TM)) with and without an apex water injection system (Cyclowash(TM)). The performance of a Pansep screen having a screening surface area of 0.5 m(2) is evaluated for size separations at 150 Pm and 45 Pm particle sizes, whereas a 15 cm diameter gMax cyclone with and without a Cyclowash attachment is studied for particle size separation at 45 pm only. The results of this study indicate that the size separation performance obtained by the Pansep screen is significantly better than the performance obtained from conventional technologies such as, cyclone and sieve bend for classifying the minus I mm particle size coal slurry at 150 mum. An excellent overall screening efficiency of 98% is obtained from the Pansep screen in comparison to the 44% obtained from the sieve bend and 57% from the raw coal classifying cyclone operating in an Illinois coal preparation plant. For the 45 mum size separation, a conventional cyclone efficiency of 37% is improved to 68% by the gMax cyclone, 70% with the use of Cyclowash attachment and to nearly 99% by the Pansep screening technology. The oversize throughput capacity of the Pansep screen for a particle size separation at 45 mum can be as high as 5 ton/h m(2) without any significant negative effect on the overall size separation efficiency. No significant deterioration in the overall screening efficiency is noticed for the particle size separation at 150 mum while obtaining the same oversize throughput indicating the possibility of obtaining higher throughput rates for coarser size separations. (C) 2002 Elsevier Science Ltd. All rights reserved.