The demands for efficient utilization of ore bodies and proper risk management in the mining industry have resulted in a new cross-disciplinary subject called geometallurgy. Geometallurgy connects geological, mineral processing and subsequent downstream processing information together to provide a comprehensive model to be used in production planning and management. A geometallurgical program is an industrial application of geometallurgy. Various approaches that are employed in geometallurgical programs include the traditional way, which uses chemical elements, the proxy method, which applies small-scale tests, and the mineralogical approach using mineralogy or the combination of those. The mineralogical approach provides the most comprehensive and versatile way to treat geometallurgical data. Therefore it was selected as a basis for this study. For the mineralogical approach, quantitative mineralogical information is needed both for the deposit and the process. The geological model must describe the minerals present, give their chemical composition, report their mass proportions (modal composition) in the ore body and describe the ore texture. The process model must be capable of using mineralogical information provided by the geological model to forecast the metallurgical performance of different geological volumes and periods. A literature survey showed that areas, where more development is needed for using the mineralogical approach, are: 1) quick and inexpensive techniques for reliable modal analysis of the ore samples; 2) ore textural characterization of the ore to forecast the liberation distribution of the ore when crushed and ground; 3) unit operation models based on particle properties (at mineral liberation level) and 4) a system capable of handling all this information and transferring it to production model. This study focuses on developing tools in these areas. A number of methods for obtaining mineral grades were evaluated with a focus on geometallurgical applicability, precision, and trueness. A new technique developed called combined method uses both quantitative X-ray powder diffraction with Rietveld refinement and the Element-to-Mineral Conversion method. The method not only delivers the required turnover for geometallurgy but also overcomes the shortcomings if X-ray powder diffraction or Element-to-Mineral Conversion were used alone. Characterization of ore texture before and after breakage provides valuable insights about the fracture pattern in comminution, the population of particles for specific ore texture and their relation to parent ore texture. In the context of the mineralogical approach to geometallurgy, predicting the particle population from ore texture is a critical step to establish an interface between geology and mineral processing. A new method called Association Indicator Matrix developed to assess breakage pattern of ore texture and analyze mineral association. The results of ore texture and particle analysis were used to generate particle population from ore texture by applying particle size distribution and breakage frequencies. The outcome matches well with experimental data specifically for magnetite ore texture. In geometallurgy, process models can be classified based on in which level the ore, i.e. the feed stream to the processing plant and each unit operation, is defined and what information subsequent streams carry. The most comprehensive level of mineral processing models is the particle-based one which includes practically all necessary information on streams for modeling unit operations. Within this study, a particle-based unit operation model was built for wet low-intensity magnetic separation, and existing size classification and grinding models were evaluated to be used in particle level. A property-based model of magnetic beneficiation plant was created based on one of the LKAB operating plants in mineral and particle level and the results were compared. Two different feeds to the plant were used. The results revealed that in the particle level, the process model is more sensitive to changes in feed property than any other levels. Particle level is more capable for process optimization for different geometallurgical domains.

Abstract In the existing JKMRC breakage testing method for AG/SAG mill modelling, ore is characterised using mainly high energy single impact tests. However, recent DEM studies have suggested that breakage in AG/SAG mills is mainly due to low energy repetitive (or multiple) collisions rather than single high energy impacts. Furthermore, several of the published AG/SAG ore hardness tests developed outside the JKMRC use laboratory tumbling mills to quantify the specific power required to grind the ore to a set product size. Comprehensive experiments were carefully designed using two mill diameters of 1.1 and 0.6 m to mimic the reported low energy repetitive impact breakage under low load conditions. The ore breakage characterisation parameters derived from high energy single impact tests were used to predict the low energy repetitive impact breakage behaviour. Significant bias has been shown to be associated with the traditional high energy single impact characterisation approach, suggesting an alternative method was required. An extensive experimental program with more than 1400 tests was conducted using a newly developed JKRBT (JKMRC Rotary Breakage Tester) device, gravity drop test and laboratory tumbling mills. Comprehensive data were collected and analysed to provide an understanding of low energy repetitive impact breakage of particles and high energy single impact breakage. Details of the experimental study and findings are presented in Chapter 5. A breakage characterisation model has been developed, which takes into account the various impact energy classes and their associated body breakage and surface breakage responses. The breakage conditions were analysed and used to derive two sets of impact breakage parameters (body breakage and surface breakage). These parameters were then combined using a procedure believed to account for the two key breakage modes in tumbling, and successfully applied to predict the breakage in the two laboratory tumbling mills. Chapter 6 presents the breakage modelling approach and results. Based on the understanding of different breakage modes, a novel particle breakage characterisation method for AG/SAG mill modelling has been proposed and validated. Different from the prior-art JKMRC approach in which the breakage tests are conducted at high energy single impact, the proposed method incorporates high energy single impact, low energy multiple impacts and a simplified tumbling test. Both breakage probability and degree of breakage are used to characterise the breakage behaviour of ores. The details of the new characterisation method can be found in Chapter 7. The studies conclude that • The JKRBT can be used to investigate rock breakage characteristics under single and repetitive impacts; • The breakage of rocks in tumbling mills (under very low load conditions) can be likened to the low energy JKRBT repetitive impact breakage. • The behaviour of particle breakage as observed in AG/SAG milling can be modelled using a combination of JKRBT and tumbling ore breakage characterization; • A methodology for ore breakage characterization for AG/SAG mill modelling has been proposed and validated using independent sets of ores samples.