Investigation of Roller Pressure and Shear Stress in the HPGR Using DEM
Paper i proceeding, 2016
HPGRs have since introduced in the 1980s (Kellerwessel, 1993; Schönert, 1988), now become
integral comminution units at several minerals processing plants around the world. Even though a lot of the
initial issues concerning performance, availability and wear have been addressed and solved there are still
phenomena and aspects which can be improved and understood further. Schönert and Sander (2002)
presented experimental results and a mechanistic model including the internal force dynamics between the
rollers and the compacted bed. They derived expressions for the pressure distribution involving most of the
influencing terms and effects. However, in order to solve the differential equations several of the terms
vanish by assumptions. The Schönert and Sander model reflects the experimental data in many aspects but
the predicted shear force distinctly deviates from the experimental results at the angular position of the
peak pressure level. This finding suggests that the particle to particle interaction and breakage process in
the different zones seen in Figure 1 are complex and difficult to model using analytical models. A
numerical modelling approach using DEM does not require the same amount of assumptions and
simplifications of boundary conditions. Hence such modelling may provide further knowledge and vital
understanding. In this paper the breakage process is simulated in order to investigate the shear slip
behaviour and how it relates to different operating variables. A laboratory scale HPGR corresponding to
the experimental setup used by Schönert (2002) have been modelled in EDEM (DEM-Solutions). The
bonded particle model (BPM) is used for modelling quartz particles (Potyondy, 2004). The breakage model
strength parameters are calibrated against interparticle breakage experiments in an Instron 400RD
compression device. The contact model parameters are calibrated using calibration methods developed by
Quist (2015). The floating roller dynamics are modelled using a spring-damper system. Results present
insights regarding the interparticle slip behaviour as well as the frictional tangential force distribution on
the rollers. The simulated roller pressure distribution shows good correspondence with previously reported
findings in the literature.
HPGR
Simulation
Comminution
DEM
Crushing
Breakage