Permittivity measurement for nickel-copper ores by open-ended coaxial probe

摘要

We can find distinction for metal mine detection by dielectric parameters differences between host rock and ore body. In addition, permittivity is the dominant factor of EM velocity, which is the basis theory of GPR. Therefore the measurement of electrical parameters is particularly essential. Compare to Transmission/Reflection coaxial line method which was traditionally used to measure the rock permittivity, the advantages of open-ended coaxial method include broadband measurement, convenience and easy sample preparation. Based on the terminal open-end probe method, we developed a set of complex permittivity of rocks test systems using spectral domain quasi-static model. And this method has a quite effective algorithm. Some previous study indicated that people usually operated with homogeneous medium using open-end probe, but rock samples obviously are heterogeneous, so we need more samples to average for one category. Then we can evaluate the permittivity of one kind of rock. In this paper, we collected nickel-cupper ore samples of different grade and its host rock samples including granitization granite, marble, hybrid diorite, lightly alterative hornblende pyroxenite, pyroxene peridotite in a metal mine in China. These samples are manufactured into smooth sheets, and measured by our open-ended coaxial probe. The determination of permittivity represents the difference of rock attributions.