Abstract:

As the energy transition is underway, the demand for critical mineral extraction is forecast to increase substantially in the near future. In-situ characterization of the mechanical property of rocks offers the potential for energy intensity reduction, water cutbacks and chemical use reduction throughout the comminution process. Laser Ultrasonic and Photoacoustic sensing techniques have the potential to provide a direct measurement of the effective hardness of rocks, a key indicator for the comminution. For ore sorting applications, these techniques have the potential to reduce the amount of rock entering the mineral processing circuit by diverting or mixing rocks based on their mechanical properties. Another application is to be used in combination with the high-power microwave-assisted comminution that selectively break rocks and sort waste from desired minerals, reducing crushing requirements. Finally, these techniques can be used for real time mineralogy assessment of ore on conveyor.
In this presentation, we will share our latest results in real-time characterization of mechanical properties for various rocks lithologies. Photoacoustic response over a grid of points at the surface of rocks to produce 2D maps of the mineralogy will be shown. Laser-based generation and detection of ultrasonic waves to analyze the internal microstructure of rocks will also be demonstrated. In particular, we compare samples from the same location in a mine but having undergone different microwave treatments, and extract ultrasonic information to characterize how the internal structure of the sample is affected by the treatment. In conclusion, opto-acoustic techniques provide in-situ and real-time information that can be used to monitor and control the feed in mineral processing, enabling optimization of concentrate impurity content while maintaining the best possible recovery of critical minerals.

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Daniel Gagnon