The Hicom mill is a high-intensity tumbling mill that can be used for fine and ultra-fine media grinding. Recent investigations on fine dry grinding with the Hicom 25 pilot plant, operating in closed circuit with an IAC 200 Inprosys high-efficiency classifier, have indicated that this milling combination is well suited to the efficient production of fine mineral powders. Closed circuit grinds were performed on 98% passing 94 mum limestone to a range of product sizes from 98% passing 26 down to 6.4 mum to determine the specific energy requirements for the milling of this material. The results from these tests show efficient classifier separation as well as rapid and efficient comminution in the Hicom mill. (C) 2002 Published by Elsevier Science Ltd.