Vertical stirred mill scale-up and simulation: Model validation by industrial samplings results

Minas-Rio is an Anglo American property, located in Brazil, which started its operation at the end of 2014. The Minas-Rio regrind circuit is currently the largest Vertimill™ installation in the world with sixteen Metso VTM-1500s installed in closed circuit with hydrocyclones. The grinding efficiency of this circuit was verified through a sampling campaign, and the results showed that the measured specific energy consumption was similar to the predicted specific energy consumption estimated at the engineering design stages of the project. Although essential for plant design, the specific energy consumption for a given product size is not sufficient to predict the performance of the circuit under different operating conditions. A more detailed model and simulations are required to predict performance under different operating conditions, so that the required product specifications can be achieved. A vertical stirred mill model, based on the Population Balance Model (PBM) technique, has recently been developed and validated using extensive data from pilot scale vertical stirred milling tests. This model is the subject of this investigation. Industrial scale data has been generated through a careful sampling campaign at the Minas-Rio plant, and used to further validate the model. PBM ore breakage parameters were obtained from the feed samples using simplified tests carried out in a laboratory scale conventional tubular ball mill and the results are discussed here.