An Investigation on the Crushing & grinding characteristics of Granite ,Blackrock and Ore-pebbles for use as grinding media in Pebble Mills at Nundydroog, Kolar Gold Mines, Mysore

Three samples of granite, blackrock and ore-pebbles were received at National Metallurgical Laboratory, from the Managing Director, Kolar Gold Mines Undertakings, the Mysore, for carrying out studies to determine which of the above would be the best for use in the Pebble Mills at Nundydroog. Grinding and crushing characteristics of these samples were determined and it was found that granite and blackrock had nearly the same grinding characteristics whereas ore pebbles were comparatively softer. Crushing tests showed that granite had a uniform strength whereas the other two samples had planes of weakness, indicating that granite which is at present used as grinding media at Nundydroog, is the best of the three samples investigated and its continuance at Nundydroog is recommended.