Joint Project for the Development of Specific Recultivation Material for the Qualified Topping of Mining Dumps and Contaminated Sites

08. March 2022


August 1, 2021 saw the start of the joint project “WIR! – rECOmine – RekuMat –Development of Specific Recultivation Material for the Qualified Topping of Mining Dumps and Contaminated Sites”.

The project partners are the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) as the project coordinator, the Veolia Sludge Recycling Germany GmbH, the SAXONIA Site Development and Management GmbH as well as the Institute for Wood Technology Dresden Non-profit GmbH.

Opening up new sources of raw materials held in mining dumps or similar contamination-fraught sites necessitates intrusion into the landscape, e.g., by re-opening sites that have at least partially overgrown again. Exploitation of raw material deposit requires swift and safe recultivation by suitable recultivation materials that are sufficiently available. Dump-heap materials left behind after extracting sought-after resource materials usually show poor physical and/or chemical soil properties, unfavourable granulometric condition and low-level microbiological activity. Even soil materials currently used, which are very heterogeneous due to their origin, generally have insufficient chemical and microbiological properties. The solution in the RekuMat Project is the use of residues, such as municipal sewage sludge and removed substrates from edible mushroom farming, as aggregates for top-soil covers. These materials are usually available regionally and provide a variety of useful properties to upgrade and enhance cover layers in the long run.

The overall goal of RekuMat is to develop and test functional recultivation materials for qualified topping systems for use on mining dumps (Fig. 1) and contaminated sites, including relevant methods for their manufacture and deployment (recomine Newsletter III.2021).

The IHD’s partial project includes investigations into the application of removed edible mushroom substrates as aggregates and their capacity to immobilise contaminants, especially focussing on the immobilisation of heavy metals or the degradation of organically critical substances.

In a first step in October 2021, samples of potential recultivation and dump materials were taken from four dumps in the Freiberg region. In a second step, substrates removed from mushroom farming and sludge compost samples from waste-water treatment were provided for investigation purposes. The selected samples were analysed chemically for heavy metals and biologically for their germ count, and they were also subjected to growth tests with mushrooms and cress plants. Then, the various samples were combined with each other or with hydro-gels. This was intended to bind or degradate contaminants or to reduce evaporation, but also to promote the generation of a microclimate to support the growth of microorganisms and plants.

In order to safeguard homogeneous functionality of the recultivation materials obtained on a laboratory scale, the investigations are pursued large-scale by the other project partners. If that turns out to be successful, the results from RekuMat will enable swift, reliable and economically as well as ecologically sensible recultivation of mining dumps in the Freiberg region by using regionally available material flows. The approaches are intended to be transferrable to other sites and regions, too.

The joint project RekuMat (Funding code: 03WIR1907) is funded by the German Federal Ministry of Education and Research (BMBF) within the scope of the funding programme “WIR! – Change by Innovation in the Region” via the Research Centre Jülich GmbH as project supporter. The duration of the project is 36 months.

Contact at the IHD:
Natalie Rangno

Fig. 1: Post-mining landscape in the Freiberg mining region