• Ground-based geophysical surveys were conducted at eight mine-tailings repositories during 2021 and 2022 to help preparing an inventory of potential sources of critical raw materials in mine-waste. Geophysical methods included ERT, DCIP, RMT, and tTEM. In this study, we show results obtained on two of the sites as an example. Integration of models of electrical properties, geological observations, historical orthophotos, and drillhole samples provided estimations of the thickness of tailings. The interpretation was extended to construct 3D models of the deposits. Moreover, the modelled electrical properties helped to study the variations in the grain size, porewater content and mineral chemistry. The used geophysical methods resulted in consistent estimations of the geophysical properties and the depth to the more resistive material below the tailings could therefore be determined with higher confidence. Variations in chargeability and phase response from inversion of DCIP data are generally more strongly related to variations in mineral content and grain size. A strong correlation was observed at one of the sites. Spectral IP measurements on samples showed Cole-Cole like spectra and a clear relationship between the frequency of the maximum phase angle and the grain size.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geofysik (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geophysics (hsv//eng)

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