Electromagnetic methods for assessing moisture content and density of an iron oxide copper gold deposits (IOCG) tailings sample

The recent catastrophic failures of tailings storage facilities (TSFs) have generated an enormous interest amongst the stakeholders for safe management of tailings. Two state parameters, namely moisture content and density of the deposited tailings, are the key to assess their degree of densification in the TSF. To that end, electromagnetic (EM) methods are strong candidates for health monitoring of TSFs as they provide a means to determine moisture content and density of porous media in a minimally invasive manner. In this paper, we have shown the applicability of two EM methods, i.e. time-domain reflectometry (TDR) and high-frequency electromagnetic (HF-EM) measurements for estimation of the degree of wetness and density of an iron oxide copper gold deposits (IOCG) tailings sample sourced from an operational mine in Australia. Through TDR measurements, we have demonstrated estimation of gravimetric moisture content, volumetric moisture content, degree of saturation, dry density and electrical conductivity of several reconstituted samples prepared at known moisture content and density. Furthermore, we have also discussed on utilisation of HF-EM method for continuous time-lapse monitoring of gravimetric moisture content of an initially saturated sample undergoing progressive dewatering. It is expected that these two methods will be applicable for measuring moisture content and density of the stored IOCG tailings material in the TSF. These will also be useful in continuously tracking moisture content of the samples providing an indication of extent of progress of dewatering of tailings. It should be noted that the study provides a proof of concept of the methodology, and a broad range of tailings need to be tested to generalise the approach.