Development and Evaluation of Fine Crushing Circuits for Energy Efficient Comminution of Iron Ore

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Comminution is an energy intensive component of mineral processing utilizing about 4% of electrical power generated in Canada. The common approach is to use crushing technologies followed by grinding in tumbling mills to achieve liberation for separation of valuable from non-valuable components of the ore. The focus of the proposed research is to extend the application of crushing in order to reduce the amount of grinding. There are several potential benefits for the development of fine crushing circuits. The energy efficiency of crushing technologies is much better than in tumbling mills. Crushing technologies generate steeper product particle size distributions than tumbling mills thereby avoiding the generation of excessively fine material that is difficult to process. Crushing is a dry process, such that fine crushing comminution represents an opportunity to conserve water. Hence, there is a need to design comminution processes that can maximize the effort in the crushing circuit. With the introduction of new fine crushing technologies, such as High Pressure Grinding Roll (HPGR), Vertical Shaft Impact (VSI) crushers and new advances in cone crushing, there is a potential to extend the application of crushers to fine particle sizes. A study will be performed to assess fine crushing circuits that include these technologies. The study will investigate a range of flowsheet options - all possible combinations of secondary, tertiary, and quaternary crushing involving cone crushers for all stages, HPGRs for tertiary and quaternary crushing stage, and the VSI for quaternary crushing. The goal is to maximize energy utilization in the crushing circuit to prepare the ore for downstream processing. The program will involve extensive modelling and simulation studies of the crushing units and circuits, followed by a series of the bench- and pilot-scale investigations to characterize the response of iron ore to each comminution device and process circuit. The research will inform the supporting organizations and the Canadian mining industry about the design and operation of novel fine crushing circuits with respect to energy efficiency and impacts on downstream processing.