Research On Iron Ore Grade Measurement Method Based On Multi-Electrode Capacitance Measuring

The average grade of mined ore is an important process index for mine production.Currently,the ore grade is generally measured using the assay method,which has the problems of slow speed and incomplete sampling.In addition,rapid measurement methods,such as measuring the elemental content on the surface of the ore to estimate the grade or measuring volume and weight to calculate the grade,are significantly influenced by the external morphology of the ore,and the measurement result error is large.Due to the close correlation between dielectric properties of ore and grade,dielectric measuring provides a new idea for rapid,real-time online ore grade measurement,which has certain theoretical value and practical significance for the construction of intelligent mines.To address the current problems of ore grade dielectric detection,the relationship between ore dielectric properties and grade was established based on the capacitive measurement model and mixed dielectric model,and the ore grade measurement method based on multi-electrode plate capacitance measurement was proposed.A multi-electrode plate capacitance sensor and its acquisition system were designed and developed.The effects of ore dielectric properties and size on measurement results were studied,and validation experiments were carried out using magnetite ore samples from a concentrator of Ansteel.The main conclusions are as follows:1.The correlation between ore dielectric properties and ore grades was researched.A theoretical formula for the indirect measurement of ore grade by measuring ore dielectric properties was derived based on the capacitive measurement model and mixed dielectric model,which found that the sensor structure,ore morphological structure,and mineral material properties are the main factors affecting the measurement results.A method for measuring the dielectric properties of ore based on multi-electrode capacitance measurement was proposed,aiming to mitigate the impact of ore morphology and enhance measurement accuracy.2.Through the research and development of a multi-electrode plate capacitance sensor data acquisition system,the theoretical model was verified with finite element simulation by COMSOL,and the multi-electrode plate capacitance sensor effectively reduced the influence of the uneven distribution of the mineral dielectric.The structure of the 8-electrode plate capacitance sensor was optimized,and the software and hardware of the multi-electrode plate capacitance sensor data acquisition system were designed.3.Through experimental studies of magnetite ore dielectric properties and grade measurement,the dielectric spectrum of magnetite and quartzite samples with various size distributions were measured.The variation law of the influence of ore size distribution on grade was studied.A measurement method based on the difference frequency capacitance ratio was proposed,reducing the influence of ore size on the measurement results.A measurement experiment was conducted on 30 groups of different-grade magnetite ore samples.The result shows that the standard error of measurement is 1.87%,and the maximum absolute error is 3.3%,which verifies the feasibility of the multi-electrode plate capacitance sensor to measure the grade of magnetite ore.