Uranium deposits serve as a significant source of rare earth elements (REE), often developed in ore aureoles as accompanying minerals. Notable examples include the sedimentary deposit at Stráž pod Ralksem, which was mined using in-situ leaching, and the metamorphic deposit at Rožná, mined by underground mining method. Both of these deposits are managed by DIAMO in the Czech Republic, highlighting their strategic importance in rare earth extraction.
Mining operations at these deposits have ceased, and remediation efforts are currently underway. However, access remains to leachate from the Stráž pod Ralskem deposited sludge after milling the ore and uranium processing from the Rožná deposit. Utilising accompanying technologies to extract rare earth elements during uranium mining presents a valuable economic opportunity. This approach ensures a more comprehensive utilisation of resources, contributing to the raw material security of Europe.
In this context the SUPREEMO project aims to develop a hydrometallurgical and REE extraction pilot at TRL7.
What mineral resources are contained within these deposits?
At Stráž pod Ralskem deposit, the mineral resource estimation for inferred resources of praseodymium (Pr) and neodymium (Nd) within the vicinity of argillitic volcanic veins in the uranium-bearing horizon (Category P2) is estimated at 2 ktonnes (kt) of Pr and Nd, derived from 12 million tonnes (Mt) at a grade of 0.007 %. Consequently, it is projected that the entire deposit could yield up to 74 kt of Pr and Nd as a by-product, alongside uranium production.
Subsequently, at Rožná deposit, approximately 11 million m3 of leached slurry, equivalent to 16 million tonnes of material, is stored in Tailings Pond K I. This material is suitable for further reprocessing to obtain REE, Nb and Ta. The tailings pond covers a floor plan area of 64.5 ha. It is a non-flow-through tailings pond, originally designed as a valley-type structure. The main atop deposited sediment.
Due to the chosen method of construction and the subsequent raising of the dams, it is only possible to use 1/3 of the volume of the deposited material. The ore mined at the Rožná deposited is composed mostly of amphibolite-biotite gneiss, followed by feldspar, quartz, pyrite, chlorite, clay minerals, graphite, carbonates, pitchblende, coffinite and other minerals. Uranium ore mining is now terminated at the Rožná mine. But the tailings pond is still operational due to the need to store the products of activities associated with the mine closure, and its content is therefore a possible source suitable for recovering other elements.
What is DIAMO’s contribution to the SUPREEMO project?
In the framework of the SUPREEMO project, a hydrometallurgical and REE extraction pilot at TRL7 (producing 50-100 kg of REO) will be engineered, constructed and demonstrated by TUKE (Prototype and Innovation Center – PaiC team) with the guidance of Chalmers University of Technology. The pilot will be installed and commissioned at the industrial and authorised premises of DIAMO since they have many years of experience in dealing with feedstock that might contain radioactive material at higher concentrations. Additionally, their facilities are qualified and authorised to deal with any radioactive materials that can be present in the feedstock after concentration.
An automated flexible and modular system will be constructed, equipped with sensors to provide a continuous on-line monitoring of process parameters (temperature, pressure, flowrates, etc.) ensuring safe operation together with a proper emergency system. Moreover, the engineering work will include specific adaptation needed to cope with the variation in the grade of the REEs concentrate and associated impurities/radioactivity in the feedstock. The modular and flexible design will allow easy upscaling and ramp-up capacity while minimising both CAPEX and OPEX. Such features will also consider any possible installation or operating constraints at DIAMO (footprint, available height, safety etc.).
Collaborating with Chalmers University of Technology and TUKE on REE recovery and acid-reutilisation for the Fen deposit, alongside testing tailings material from the Rožná deposit and concentrated solutions after uranium ISL in Stráž pod Ralskem, highlights the commitment to advancing sustainable extraction technologies. The pilot REE extraction efforts at the Dolní Rožínka and Stráž pod Ralskem DIAMO facilities further underscore the potential of leveraging material from the Fen, Stráž pod Ralskem, and Rožná deposits to optimize resource utilization and support the development of innovative, environmentally conscious solutions.
Given that more than 50 % of the world’s uranium production is carried out by the in-situ leaching (ISL) method from deposits of a similar nature as in the Czech Republic, supplementing this technology with the possible extraction of other valuable elements, especially REE, seems not only reasonable but also effective. Therefore, the SUPREEMO project results obtained with the help of DIAMO in this area will be significant.
Pilot ionex REE separation unit in Stráž pod Ralskem (©DIAMO)
