Incremental damage and particle size reduction in a pilot SAG mill: DEM breakage method extension and validation. (November 2018)

• Record Type: Journal Article
• Authors: Cleary, Paul W.; Morrison, Rob D.; Delaney, Gary W.
• Is Part Of: Minerals engineering. Volume 128(2018)
• Page Start: 56
• Page End: 68
• Publication Date: 2018-11
• Subjects: Comminution -- Incremental damage -- SAG mill -- DEM -- Breakage -- Validation; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2018.08.021
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: A method for including incremental damage breakage in DEM is presented. Inclusion of all comminution mechanisms allows prediction of particle size evolution. Surface mass loss is critical for reducing particle sizes to where damage occurs. The energy split between ball and rock during collisions is important for damage. Close agreement between predicted and actual particle sizes validates the method. Abstract: Applying DEM to prediction of tumbling mill performance is challenging because several different modes of breakage are active in the process. Here we use measured data from a well characterised ore in a well instrumented, 1.2 m diameter pilot scale mill to validate direct DEM prediction of particle size reduction. The key comminution mechanisms involved for a SAG mill are: (1) incremental breakage where parent particles break into progeny based on the cumulative energy absorption above the elastic damage threshold, (2) abrasion, and (3) chipping/rounding due to preferential contact and breakage of corners and edges of non-round particles. In this paper, a method for including incremental damage breakage in DEM is presented. The inclusion of all the size reduction mechanisms in the same DEM framework allows direct prediction of the evolution of the resident rock particle size and shape distributions and the product throughput rate. The surface mass loss mechanisms are shown to be critical for reducing the particle size to the point where the accumulation of incremental damage becomes significant leading to body breakage of these damaged particles. The energy split between ball and rock is also important for exceeding the elastic threshold and creating damage. Comparison of the predicted particle sizes at the completion of ten minutes of grinding operation with the measured experimental values from the pilot mill provides quantitative validation of the breakage predictions of this DEM breakage model.