The Robert M. Buchan Department of Mining Graduate Theses

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https://hdl.handle.net/1974/832

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Concentration of Graphite from Black Mountain Ore using Electrostatic Separation, Air Separation and Flotation
(2024-09-13) Adeyemo, Adewumi Joseph; Mining Engineering; Gibson, Charlotte
Flotation, a wet method that involves appropriate quantity of water with reagents, is a common technique for graphite beneficiation. However, due to environmental concerns—such as limited access to fresh water in arid environments or depletion of water bodies from consumption and pollution from tailing —alternative approaches are sought. The primary objective of this project was to limit water and reagent consumption during graphite flotation. Consequently, dry beneficiation methods like air separation, electrostatic separation, and magnetic separation were explored as integral parts of the flotation process for Black Mountain graphite ore located near Matawatchan, Ontario, Canada. Emphasis was placed on integrating air separation and magnetic separation, as the separation results obtained from this combination are promising. The air separator was specially designed with button magnets incorporated into its feed chamber allowing minerals like quartz to be successfully removed by the fluidizing action of air, while some paramagnetic minerals were removed by the button magnet. A full factorial design of experiment (DOE) with two levels and four factors was employed to optimize the air separation process. The increase in grade from 3.05% to 80% C with a 13% recovery for particles sized -850/+600 µm and from 4.23% to 88% C with a 40% recovery for particles sized -600/+420 µm suggests that the integration of the air separator with a button magnet holds promising potential for the recovery of large graphite flakes from the Black Mountain graphite ore.
Real-time Grinding Energy Consumption Forecast and Control with Machine Learning
(2024-09-06) Tureoglu, Ekin; Mining Engineering; Sari, Yuksel Asli
Comminution is the most energy-intensive stage in mineral processing and accounts for up to 50% of the total energy consumption in mining operations. This stage, particularly the grinding process, involves a series of strategically arranged mills—rod and ball mills in this case—designed to reduce the material. In an open circuit rod mill and closed circuit ball mill configuration adjusting specific key mill parameters can significantly influence the energy consumed. This research presents an approach to forecasting power consumption in rod and ball mills using machine learning models. The study focuses on predicting power usage 20 minutes into the future and interpreting the impact of various mill parameters on power efficiency. The machine learning models developed forecasted the power consumption, achieving R2 values of 0.82, 0.73, 0.84, and 0.86 for XGBoost, Random Forest Regressor, Support Vector Regressor, and Deep Neural Networks models, respectively, for the rod mill. For the entire circuit, including both rod and ball mills, the R2 scores were 0.74, 0.73, 0.70, and 0.50 for the respective models. The study highlights the critical role of optimizing grinding circuits to enhance energy efficiency in mineral processing. Given the high cost of the milling process, inefficiencies in grinding circuits, particularly those using rod and ball mills, result in significant energy waste. Unlike previous studies, which primarily focus on predicting power consumption in SAG mills and optimizing production without considering energy constraints, this research presents a machine learning-based recommendation system to achieve power reduction while maintaining production level and particle size targets. Utilizing historical data from a mineral processing plant, a reinforcement learning-based recommendation engine was developed to suggest adjustments to the rod mill's water flow, achieving a projected power reduction of up to 2%, equivalent to 299.24 Megawatt hours annually. This research emphasizes the considerable potential for enhancing sustainability and reducing costs in mineral processing through the utilization of machine learning to adjust mill parameters.
An Investigation Into Hydroxamic Acid and Amine Collectors for Enhanced Pyrochlore Flotation Efficiency
(2024-09-05) Berin-Costain, Petra Linnea; Mining Engineering; Gibson, Charlotte; Sauber, Maziar
Current large-scale niobium mineral beneficiation processes upgrade ores with a narrow range of mineralogical characteristics. These flowsheets are related by their use of cationic amine collectors to selectively float the niobium-bearing mineral pyrochlore under acidic conditions. Not only are niobium losses high due to the number of stages, but such processes are also not easily applied to finely disseminated, low grade ores. Hydroxamic acid (HA) collectors have been studied as part of a growing body of work on alternative pyrochlore beneficiation methods due to their resistance to slimes, strong transition metal chelation mechanisms, and ability to float pyrochlore at neutral pH. However, the high reagent doses reported in the literature have prevented HA collectors from seeing application in large scale operations. This work addresses the need for process development specific to finely disseminated pyrochlore bearing ores, which are currently considered untenable for upgrading. In this study, the effects of collector dissolution, air flow, pulp density, and HA dosage on rougher flotation performance were investigated. A concentrate with a grade of 6.1 % Nb2O5 and 94.5% niobium recovery was achieved from a single rougher flotation stage with a benzohydroxamic (BHA) acid collector. Furthermore, the BHA dosage was reduced from 5400 g/t to 2300 g/t with an increase in pulp density. It was found that BHA dosage could be further reduced to 1572 g/t with the addition of a cleaner stage, producing a concentrate grade of 7.8 % Nb2O5 with 84.5% niobium recovery. An amine cleaner flotation stage was studied to upgrade the rougher concentrate produced using BHA. For pyrochlore promotion, the pH needed to be lowered from 7.5 to 1.5. Despite the bulk gangue rejection in the rougher stage and a hydrochloric acid leach, the amine flotation suffered from significant buffering due to the presence of residual reactive calcites. Finally, a Central Composite Design was employed to model the effects of hydroxamic acid dosage, pulp density, and transformer oil dosage on Nb2O5 grade and recovery. The model, paired with UV visible spectroscopy analysis of the pulp filtrate has contributed to understanding hydroxamic acid’s potential to upgrade ores previously considered untenable.
Investigation of High-Power Microwave Treatment of Kimberlites and Its Effect on Comminution and Downstream Processing
(2024-06-12) Borhan Mehr, Ravash; Mining Engineering; Pickles, Christopher
Although microwave treatment has been proven to reduce the competency of kimberlites, the lack of information regarding the downstream processing of microwave treated kimberlites has led to limited application of this technology on a full scale. This thesis provides expansive research on the effects of microwave treatment on the processing of kimberlites, beginning with an in-depth literature review that evaluates its impact on the thermal, physical, and mechanical properties of various materials, as well as downstream processes such as flotation and leaching, and energy consumption. The research investigates microwave treatment at both bench-scale and pilot-scale to address the current gap in knowledge concerning the downstream processing of microwave-treated kimberlites. An extensive characterization of four unique kimberlite samples was performed, including mineralogical analysis, thermogravimetric analysis, and permittivity measurements. The bench-scale microwave treatments explored the heating behaviours and microwave amenability of the kimberlites with respect to different parameters, functioning as the precursor for pilot-scale studies which mainly aimed to reduce the kimberlite’s competency by promoting microfractures along the mineral grain boundaries. This microfracturing resulted in reduced energy consumptions during the comminution stages and has the potential to decrease diamond breakage. Comparative comminution studies, applying jaw and cone crushers followed by high-pressure grinding rolls (HPGR), indicated that the microwave treated samples not only consumed less energy by 16%, but also produced fewer ultra-fine particles (<38 μm) as compared to the untreated samples by 4.4%. Dense media separation (DMS) was then employed as the downstream processing stage to investigate the separation efficiency of the microwave treated versus the untreated samples, with a focus on liberation analysis for both the concentrates and the tailings. Settling studies on the fine particles (<1 mm) highlighted the improvements in solid-liquid separation, essential for tailings management and the design of thickeners. The key findings and the recommendations presented at the end of this thesis highlight the effectiveness of microwave treatment in the processing of kimberlites and offer comprehensive suggestions and directions for future research aimed at commercialization.
Investigations on Wollastonite Beneficiation Using Physical Methods of Separation
(2024-05-30) Owusu-Addo, Gloria Adjubi; Mining Engineering; Charlotte, Gibson; Sadan, Kelebek
Wollastonite (CaSiO3) is a fibrous silicate industrial mineral experiencing rapid growth in demand, yet it remains underrepresented in the literature. Its unique properties make it valuable in industrial, ecological, and agricultural applications, including its potential to sequester CO2, thereby mitigating global warming, and its use in wastewater treatment. Wollastonite has also replaced asbestos in many applications due to its fibrous nature, anti-carcinogenic properties, and high aspect ratio. However, wollastonite deposits are relatively scarce, with notable occurrences in China, the United States, Finland, Mexico, India, and Canada. The aqueous processing of wollastonite from its gangue presents challenges due to the limited differences in their silicate anions and common calcium cations, which complicates beneficiation using a single technique. Consequently, processing flowsheets typically incorporate multiple techniques. While flotation as a physicochemical method of wollastonite beneficiation is well-documented, other potential methods remain underexplored. This thesis investigated gravity and air separation processing techniques aimed at improving the grade and recovery of wollastonite. A traditional wet Wilfley table was used in a CCD-DOE approach with varying parameters, achieving a grade of 60.4% and a recovery of 50.8%. Modifications to the Wilfley table included the use of emery papers and white paper board, the latter showing some potential for separation, though not efficiently. Pre-treatment of wollastonite minerals with DDA.HCl and TA before running on the Wilfley table significantly affected the -180+106 µm fraction of pure diopside, increasing its concentrate recovery by 13.9% and decreasing its tailing recovery by 19.9%. Conversely, the -106+45 µm pure wollastonite fraction saw the highest increase in tailing recovery by 7% and a reduction in concentrate by 10.0%. Additionally, air separation tests on wollastonite ore indicated that diopside particles travelled shorter distances with decreasing grade as distance increased, whereas wollastonite particles exhibited higher grades at longer distances under a pressure of 20 psi. Despite some improvements, the separation efficiency observed on the physical methods of separation investigated remained suboptimal, requiring further research.

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