Discrete element method modelling of particle breakage and wear in High Pressure Grinding Rolls

High pressure grinding rolls (HPGRs) have been widely adopted as comminution technology in various industries due to their high efficiency and productivity. Despite extensive research on HPGRs, accurately prediction and optimisation of HPGRs remains challenging. This study aims to develop a comprehensive model based on the discrete element method (DEM) to investigate the grinding process of HPGR and understand the underlying mechanisms. A laboratory-scale geometrical model of the HPGR mill was developed and the dynamic response of the rolls in the mill was simulated. The multi-body dynamics (MBD) model has been validated to accurately simulate the dynamic response of the rolls. The micro-phenomena of particles, such as breakage behaviour and strength weakening were investigated and calibrated by implementing a particle breakage model. This model was employed to simulate the particle breakage occurring during the grinding process, analysing the principle of breakage mechanism and predicting the grinding efficiency of the mill. Investigations into the effects of roll speed and grinding pressure on grinding performance demonstrated that an increase in roll speed leads to higher throughput and power consumption. Conversely, increasing the grinding pressure reduces throughput due to a smaller working gap. Furthermore, research on multiple grinding cycles showed that particles subjected to a second grinding process were finer and weaker than those after the first round, indicating the importance of accounting for both particle size and strength when modelling to predict HPGR performance under different operating conditions Wear is still a significant issue that cannot be ignored for HPGR. The evolution of wear on roll surface and the effect of wear on grinding performance of HPGR were investigated. The DEM model was coupled with a wear model to simulate wear behaviour. A predictive analysis of wear on the HPGR was conducted. The DEM model coupled with a wear model to predict the evolution of wear of a lab-scale HPGR mill and to investigate how wear affects mill operation and particle breakage. Results showed a parabolic wear profile on rolls, with the rear section of the stud wearing most due to combined compression and abrasion effects. Moreover, increasing wear had no visible effect on the throughput but significantly reduced the power draw of the mill. Particle breakage in three mills with different degrees of wear was simulated. The results showed that as wear increased, the mill's grinding efficiency decreased, leading to coarser products; thus, a worn mill necessitates more comminution cycles to match the performance of a new one. In summary, a model based on the DEM model has been developed and used to simulate the grinding process of the HPGR mill. This work has demonstrated that the DEM model is a powerful numerical alternative capable of effectively investigating the HPGR technology.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2023

Author dc:creator

• Zou, Yudong ; https://orcid.org/0000-0003-0898-4385

• Discrete element method
• Particle breakage
• HPGR
• Wear evolution
• Comminution
• anzsrc-for: 4016 Materials engineering
• anzsrc-for: 400407 Process control and simulation

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/25371

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/101664