Passive Leached Waste Metal Remediation

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Innovate UK
Innovate UK
Innovate UK
Innovate UK
Innovate UK

£1,354,305

Sept. 30, 2022

March 31, 2024

Once important contributors to the UK economy and employment, abandoned metal mines have created a problematic legacy, causing pollution in many of our rivers and streams. When in use, the mines were pumped to keep the underground workings dry, however after abandonment the pumps were removed and slowly the mines filled with water. Reacting with metal ore, the water formed acid solutions, rich in dissolved metal, which has now found its way to the surface of the Earth and mixed with over 200km of rivers in Wales alone, with 453 water bodies breaching legislation throughout the UK for metals including lead, zinc and cadmium. Many methods for treating mine water pollution are challenging to deploy in remote areas of upland Britain where many of the mines are.

Over the last 2 years, we have developed and scaled-up a low carbon, low cost passive filter system process (passive leached waste metals, PLWM) using a material derived from seaweed, which has excellent metal capture properties. We have demonstrated in trials of up to 3 months duration that we can capture nearly all the metal pollution.

The main advantage of PLWM is the high efficiency of metal removal, within minutes. This means PLWM does not need to hold back large volumes of water to allow time for the treatment to work and extensive, and expensive, civil engineering works are not required and visual impact and land requirements minimised. PLWM has several other advantages over alternative methods for metal mine treatment, including: very low energy demands to run the gravity fed filters, very efficient metal capture, a sustainable and near carbon neutral main filter material and low maintenance needs.

In this project, PLWM will be both scaled up to 10,000 L scale and run continuously for a year at Cwmystwyth metal mine in Wales providing critical performance data for subsequent commercialisation. In addition the previous trial identified modifications needed to improve zinc capture and, therefore, integrated chemical dosing will be introduced to PLWM in the project. Finally, integrated filter material recycling will be trialled at scale, producing an acid liquor containing the captured metals for offsite metal recovery, providing a circular economy route to metal supply and waste reduction.