Discrete element method (DEM) modelling of rock flow and breakage within a cone crusher
Li, Huiqi (2013) Discrete element method (DEM) modelling of rock flow and breakage within a cone crusher. PhD thesis, University of Nottingham.
A cone crusher is a crushing machine which is widely used in the mining, construction and recycling industries. Previous research studies have proposed empirical mathematical models to simulate the operational performance of a cone crusher. These models attempt to match the size distributions of the feed and product streams. The flow of the rock and its breakage within the cone crusher chamber are not explicitly modelled by these methods. Moreover, the ability to investigate the changes in crusher performance affected by changes to the crusher design geometry and/or operating variables (including cavity profile, closed size setting and eccentric speed) are not easily achieved. Improvements to system design and performance are normally achieved by the combination of iterative modifications made to the design and manufacture of a series of prototype machines, and from a subsequent analysis of the results obtained from expensive and time consuming rock testing programs. The discrete element method (DEM) has in recent years proved to be a powerful tool in the execution of fundamental research to investigate the behaviour of granular material flow and rock breakage. Consequently, DEM models may provide the computational means to simulate the flow and breakage of rock as it passes through a cone crusher chamber. Thus, the development of field validated models may provide a cost effective tool to predict the changes in crusher performance that may be produced by incremental changes made to the dimensions or power delivered to the crusher chamber. To obtain an improved understanding of the fundamental mechanisms that take place within a cone crusher chamber, the two processes of rock flow and rock breakage may be decoupled. Consequently, this study firstly characterised the flow behaviour of broken rock through a static crusher chamber by conducting a series of experiments to investigate the flow of regular river pebbles down an inclined chute. A parallel computational study constructed and solved a series of DEM models to replicate the results of these experimental studies. An analysis of the results of these studies concluded that an accurate model replication of the shape of the pebbles and the method used to load the pebbles into the inclined chute were important to ensure that the DEM models successfully reproduced the observed particle flow behaviour. These studies also established relationships between the chute geometry and the time taken for the loaded pebble streams to clear the chute.
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