35-7 Assessing the Potential for Critical Metals Recovery from Mine Waste along the Carnon River, UK

Session: Minerals in Motion: Tracking Mineral Reactions Using In Situ and Synchrotron Techniques, A Celebration of the Career of Peter Heaney (Posters)

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Abstract:

In Cornwall, UK, the history of mining dating back to Britain’s Bronze Age around 2000 BC has led to a legacy of contaminated soils and waterways along the Carnon River. Two historic mining sites in the area include the Wheal Maid and Wheal Jane mines, legacies of regional tin, copper and arsenic mining. Wheal Maid is also part of a designated World Heritage Site and is a popular area for walking and mountain biking, despite the risk of arsenic exposure. In this work, we collected and analyzed water and sediment samples, and incorporated data collected by various agencies into our analyses, ranging from compliance audits to surface water samples from the UK’s Environmental Agency, to expand our understanding of potential critical metals recovery from mine-waste along the Carnon River.

Water and sediment samples were collected from Wheal Maid, Wheal Jane, and nearby impacted areas. Water samples were analyzed with inductively coupled plasma mass spectroscopy (ICP-MS). Sediment samples were analyzed with X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Water sample analyses suggested elevated concentrations of critical metals such as Li, Cu, As, and Zn in a Wheal Maid seepage pond and the sample from the Wheal Jane Water Treatment Plant when compared to acid mine water standards. Water quality data from the Environmental Agency database helped identify possible sources of critical metals into the river and showed mixing effects downstream of conjoining tributaries.

When normalized to upper continental crust surface averages, sediment samples were recorded with elevated concentrations of Cu, Zn, As, Ag, Sn, W, and Pb. For REEs, samples were more enriched than the Loongana (CL) chondrite standard. SEM/EDS analysis indicated that iron sulfide minerals host critical metals such as As, Zn, and Cu. Critical metals were also generally associated with the smaller particle size fractions. REEs tended to occur in small, zircon-like particles. Principal component analysis on XRF data of sieved particle size fractions of sediment samples could be used to draw similar conclusions regarding the mineralogical association of critical elements, if interpreted through the lens of the SEM/EDS analyses. This study highlights how datasets across different sources can build a clearer picture for potential critical metals recovery from mine-waste.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8785

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