Measurement of Mined Ore Grade Based on a Capacitance Sensor

To address the difficulty of rapidly determining run-of-mine (ROM) ore grade, this study proposes a capacitive grade-estimation method based on the dielectric contrast between ore and waste rock. A theoretical relationship between capacitance and ore grade was established, and a bucket-integrated three-electrode sensor was investigated using COMSOL Multiphysics simulations and a geometrically scaled laboratory prototype. A statistical prediction model incorporating three mutual capacitance measurements and total sample mass was calibrated using 33 samples and evaluated using 50 randomly prepared samples. The results showed that particle size and spatial arrangement had pronounced effects on the capacitance response. For the validation samples, the coefficient of determination was R2 = 0.918, the mass-weighted mean signed error was −1.23 percentage points, and the maximum absolute error was 11.4 percentage points. In the material arrangement experiment, the prediction error decreased from approximately 17.4 percentage points to below 0.2 percentage points after the same sample was thoroughly remixed, demonstrating the importance of material distribution to measurement performance. These results verify the feasibility of combining multi-electrode capacitance measurements with sample mass for ROM ore-grade estimation and provide an experimental basis for further sensor optimization and engineering development.