Technology and technics of ore preparation processes 14 EURASIAN MINING • 1. 2015 These grinding rolls exhibited higher capacity and lower energy consumption than was expected. A single Polycom24/17 treated over 3 thousand tons of goldbearing copper ore per hour. Cerro Verde mine HPGHR grinds 120 thousand t/ day as against 108 thousand t specified by the equipment standard. This can .