Desaturation effects of pyrite–sand mixtures on induced polarization signals

SUMMARY Induced polarization (IP) is an acknowledged method in ore exploration and can be applied to evaluate the metal content dumps containing residues of processing facilities. Existing models explain relationships between grain size particles with IP parameters. However, assume full water saturation samples, which often not case field conditions at dump sites. Hence, our study investigates effect desaturation on resulting signal. We used six different sand–pyrite mixtures varying amount sizes pyrite particles. Evaporative drying desaturated samples. Complex conductivity spectra were recorded frequency range 0.02 1000 Hz certain levels. The indicate decrease amplitude progressing desaturation. This agrees second empirical Archie equation. exponent shows values slightly larger than one. measured processed by a Debye decomposition. observe nearly constant total chargeability during finding agreement existing that relate sample. mean relaxation time decreases remarkably process, whereas normalized time, considers ratio resistivity embedding material, does any dependence saturation. behaviour contradicts predict decreasing increasing salinity, results from evaporative drying. In order observed effects, we propose conceptional model compares mixture material (sand, air) electrical RC circuit. grains behave as small condensers are charged discharged via conductive background material. According this simple physical model, proportional A increase while causes experiments. good other experiments change salinity or clay content. capacitive dispersed characterized depends volume