Conference Agenda

Legacy Mine Impacts
Thursday, 15/July/2021:
12:40pm - 2:20pm

Session Chair: Tom Williams
Location: Meeting Room 1

12:40pm - 1:05pm

Using Geological Analogues And Proxies To Better Determine AMD Risk

Timothy Wright1, Steven Pearce1, Janjan Hertrijana2, Latipa Henin2, Muhammad Hidyat2

1Mine Environment Management Ltd, United Kingdom; 2PT Agincourt Resources, Indonesia

We present initial results from a combined structural and geochemical assessment designed to improve AMD classification at the Martabe gold mine, Indonesia. Martabe conforms to a classic epithermal acid sulfate model displaying local variations in structure and geochemistry that are difficult to constrain using existing resource models. Fracture-controlled mineralisation and oxidation explains the observed irregular and incomplete “oxidation zones” in which Jarosite, a non-sulfide cause of AMD is found. Supported by outcrop analogues such as the Rodalquilar gold mine in SE Spain, these observations imply detailed grade control drilling is justified to improve model resolution and improve waste rock management efficiency.

1:05pm - 1:30pm

Laboratory Testing To Determine The Effectiveness Of Capping And Risk Of Long-term Metal Release From Mine Waste At The Abandoned Abbey Consols Lead-Zinc Mine, Wales, UK

Julia Dent1, Andrew Barnes2, Ben Gersten2, Mark Roberts2, Tom Williams3, Thomas Eckhardt4

1Mine Environment Management, Vale Street, Denbigh, Denbighshire, UK, LL16 3AD; 2Geochemic Ltd, Lower Race, Pontypool, Wales UK, NP4 5UH; 3Natural Resources Wales, Swansea University Singleton Campus; 4WSP UK Ltd, Kings Orchard, 1 Queen Street, Bristol, BS2 0HQ, UK

The effectiveness of a proposed low permeability cover system for historical mining waste at the abandoned Abbey Consols lead-zinc mine, Wales, UK, was tested using laboratory columns. A reduced infiltration rate could still result in release of metals reducing the benefits of the cover system. Two column scenarios simulated average infiltration conditions and a reduced infiltration rate (the low permeability cover). Results showed the reduced infiltration column produced higher concentrations of key solutes (cadmium, lead and zinc) but a lower load. Zinc and cadmium loads narrowed between the two columns over time suggesting the low permeability cover benefit diminishes.

1:30pm - 1:55pm

Tracing The Water – Rock Interaction In The Ibbenbüren Mine - Towards A Reactive Transport Model For Coal Mine Drainage

Thomas Rinder1, Diego Bedoya Gonzalez1,2, Sylke Hilberg1

1University of Salzburg, Department of Geography and Geology, Hellbrunner Str. 34, 5020 Salzburg, Austria; 2University of Greifswald, Institute for Geography and Geology, Friedrich-Ludwig-Jahn Str. 17a, 17487 Greifswald, Germany

Traces of water-rock interaction in two drill cores from the West field of the former Ibbenbüren anthracite coal were related to both diagenesis and relatively recent weathering processes along open fractures. The coupled appearance of kaolinite-dickite-illite minerals in weathered and unweathered rock sections was clearly connected to the burial history of the Carboniferous sequence. In contrast, the formation of iron (oxide-) hydroxides together with the presence of oxidized pyrite in weathering profiles along both sides of the fractures was positively related to the geochemical footprint of the coal mine drainage.

1:55pm - 2:20pm

The Importance of Adequate Waste Rock Characterization: A Case Study of Unsuccessful Drainage Quality Prediction

Teemu Eemeli Karlsson1,2, Muhammad Muniruzzaman3,4, Päivi M. Kauppila1, Lena Alakangas2, Marja Lehtonen5

1Circular Economy Solutions, Geological Survey of Finland, Neulaniementie 5, 70211 Kuopio, Finland; 2Department of Civil, Environmental and Natural Resources Engineering, Division of Geosciences and Environmental Engineering, Luleå University of Technology, 97187 Luleå, Sweden; 3Water Management Solutions, Geological Survey of Finland, Vuorimiehentie 5, 02151 Espoo, Finland; 4Department of Environmental Engineering, Technical University of Denmark, Miljøvej, Building 115, 2800 Kgs. Lyngby, Denmark; 5Circular Economy Solutions, Geological Survey of Finland, 02151 Espoo, Finland

Current Finnish practices in waste rock characterization may result in improper drainage quality prediction. In this paper, we present a case study involving such inadequate predictions. Our results demonstrated that the waste rock materials with relatively low contents of harmful elements and S can still produce poor-quality drainage, and the waste rock characterization approach developed by the government should be re-evaluated. Special attention should be paid to low carbon content, low neutralization potential, and geochemical properties of single rock types rather than average concentrations of the whole rock mass.