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Granular material flow into cable shovel dippers
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- Author / Creator
- Rasimarzabadi, Raheleh
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Electric cable (or rope) shovels are critical equipment in the surface mining industry. An improved understanding of the factors that affect the flow of broken material into the dipper during loading can help to evaluate the performance of the excavator, define the criteria for equipment selection, and develop ways to mitigate equipment damage caused by broken particles. In this thesis, the flow pattern of angular cohesion-less granules loading into a cable shovel dipper was investigated both experimentally and numerically. The experimental study was performed through a series of laboratory tests by moving 1:32 and 1:20 (cube root scale) models of a 44m³ dipper through a test bin filled with angular crushed limestone. The influence of several parameters, including hoist speed, dipper pitch angel, and dipper size on the flow pattern, was investigated qualitatively and quantitatively. In the numerical study, a 2D model was generated to simulate the filling of a cable shovel dipper, using PFC version 5.0 developed by Itasca. To verify the accuracy of the model, the results were compared to the experimentally measured results. Afterwards, a series of the model was developed to investigate the influence of particle shapes, particle sizes, and the role of the dipper tooth on the material behaviour. Compared to experimental measurements, there was a good agreement between DEM (Discrete Element Modeling) and the lab experiments in identifying the filling procedure. The numerical model predicted all stages of filling, and the flowing layers of the particles. Due to the shortcomings and limitations, DEM was inaccurate in modeling the material properties, resulting in a lower resistance against digging via the dipper. Based on the performed experimental and numerical investigations, angular cohesion-less material follows a specific flow pattern loading into a cable shovel dipper. This flow pattern is independent on the examined dig conditions and material properties, however, such parameters may influence the filling procedure, and therefore the productivity of the machine. For instance, in a specific period of time, employing a lower dipper angle and a faster dig time results in a higher number of completed dig cycles due to shorter dig times, and a higher amount of payload at each dig cycle due to a lower dipper angle, and both contribute an improved machine productivity. Employing a bigger size dipper although increase the amount of payload due to a wider lip length, it does not necessarily result in a high fill factor. Applying an appropriate depth of penetration according to the dipper size is one of the considerable factors. Dipper tooth is another parameter that results in a higher amount of payload due to a deeper penetration into the rock-pile. Regarding to material properties, increasing particle size and angularity has inverse effect on the machine productivity and reduces the dipper fill factor. One of the interesting findings of this study was identifying the procedure of creating the empty space in side the dipper during a dig cycle. Creating such a void space is a function of material properties, especially material internal friction coefficient, that results in a reduced fill factor and even over estimation of the payload.
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- Graduation date
- Fall 2016
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.