01/06/2016 · High pressure grinding rolls (roller presses) are used in both cement raw materials (limestone, clay, shale etc.) and cement grinding stages. The energy consumption is – kW h/t and about 10 kW h/t when recycling of the material is HPGR consumes 30–50% less specific energy as compared to a ball mill which indies higher comminution efficiency for a HPGR.