Aspects of roller press for the comminution of crushed iron ores

Mining industries have faced a huge challenge to reduce cost, especially, in ore comminution that can reach more than 60 % of the total power consumption of mineral beneficiation plants. High-pressure grinding rolls (HPGR) has been used as an alternative when combined with the traditional autogenous or semi-autogenous (AG/SAG) grinding mill in the comminution of run-of-mine iron ores. Four similar pilot scale runs were performed in a closed circuit in order to evaluate the impact of HPGR processing on subsequent grinding for different lithologies. A considerable decrease in power consumption for the grinding process was observed after HPGR comminution. Furthermore, a good coefficient of determination (R² > 0.84) was observed between the Bond work index (WI) of the fresh feed and the WI of the HPGR product. This leads to a significant decrease in operational and capital expenditures (OPEX and CAPEX). Since the energy consumption has impact on carbon dioxide emissions, adopting this unit operation prior to conventional grinding reduces greenhouse gas emissions.