- Title
- Numerical analysis of the packing characteristics of iron ore granules using discrete element method
- Creator
- Li, Chengzhi
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- In the sintering process, the iron ore fines are first agglomerated into granules in a rotating drum. The formed granules are then charged onto a sinter strand where the packed iron ore granules are converted into a bed of sinter. During the charging process, the granule behaviour strongly affects the structural properties (e.g. permeability) of the packed green bed and hence finally affects the sintering productivity and sinter quality. Therefore, an analysis of the macroscopic behaviour of iron ore granules during the charging process is of great interest to ironmaking researchers for optimising the sintering process. The research work presented in the thesis is composed of three parts. The first part of the research is focused on gaining knowledge of the physical characteristics of three types of Australian iron ore fines and the iron ore granules agglomerated under varying moisture conditions. This experimental work provides not only an understanding of the physical properties of iron ore granules as a function of moisture, but also valuable information of the granule parameters to be used as input in the following simulation work. The second part of the research is building a model, using Discrete Element Method (DEM), capable of representing the iron ore granules and accurately simulating the interactions between them. Using this model, the formation of iron ore granule piles in a rectangular dropbox has been simulated and two important packing characteristics, the angle of repose and size segregation, were investigated in detail. The model has been also well validated via conducting a series of corresponding experimental tests. The final part of the research is adapting the established model to a simplified sintering configuration. The objective is to predict the flow and packing behaviour of iron ore granules under varying sets of operating conditions in a lab-scale sintering process. In this work, the effects of feed rate and rill plate angle on bed size segregation and bed voidage have been studied. The simulation results were well validated via conducting a series of corresponding experiments, indicating the model capability in analysing the iron ore granule behaviour under a set of sintering operation conditions. Research findings show that an increase in feed rate (from 6 kg/s/m to 18 kg/s/m) significantly decreased the level of vertical size segregation and the voidage of the green bed. This is because increasing the feed rate impeded the size segregation on the rill plate and also enhanced the green bed avalanching, which resulted in a larger mixing degree for the granules flowing down the bed in the vertical direction. With the increase in rill plate angle (from 45° to 65°), the vertical size segregation first decreased and then slightly increased while the average bed voidage first decreased and then remained relatively constant. This complex effect derived from the change in the initial velocity of the granules when they impacted against the rill plate and the flow length on the rill plate, which, in turn, influence the final horizontal velocity separation of the multi-sized granules at the end of the rill plate. In future work, it is recommended that the DEM model be further improved, aiming to achieve a numerical sintering configuration comparable to the industrial one. For example, the model geometry should be scaled up to match the full-scale sinter machine. The granule mixture having a simplified size distribution compared with the industrial sinter feed should also be adopted in the model to speed up the computation. Furthermore, the necessity of incorporating cohesive force between iron ore granules into the model will be discussed. This advanced model will lay a foundation for future investigations into the structural properties of green bed and allow recommendations to be made for the design and operation of sinter strands.
- Subject
- DEM; iron ore granules; angle of repose; size segregation; voidage; sintering bed
- Identifier
- http://hdl.handle.net/1959.13/1402470
- Identifier
- uon:35031
- Rights
- Copyright 2019 Chengzhi Li
- Language
- eng
- Full Text
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|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 372 KB | Adobe Acrobat PDF | View Details Download |