At the TUKE laboratories, the work with material from the Fen deposit began with a careful and methodical preparation process. Each delivery was documented before being processed through a series of crushing and grinding steps designed to prepare the ore for testing. The initial crushing was carried out using a jaw crusher, where an adjustable gap allowed control over the desired particle size. Following this, the material was divided into representative portions using quartering, ensuring uniformity and consistency across samples. A selected portion was then finely ground using a laboratory ball mill and then stored in sealed containers to preserve it for subsequent flotation or gravity-based separation tests.
Achieving the right particle size was a very important factor during processing. In order to separate the rare earth elements of interest, it was necessary to reduce the size of the particles to the point where the individual mineral grains were completely liberated from one another. In this case, the material was ground until the P80 size was 75 micrometres.
The mineralogical analysis offered insight over the proportion of main phases. XRD testing revealed that the main phases present were calcite, dolomite, and ankerite, with apatite identified as an important carrier of light rare earth elements (LREE). Additionally, heavy minerals such as hematite and barite were also identified, especially when gravity separation was applied.
With the mineralogy understood, attention turned to improve the flotation process. Much of the initial efforts were centred on finding the most suitable flotation collector — a chemical that helps certain minerals attach to bubbles and separate from the rest of the material. The choice of flotation reagents (chemicals used in the process) was based on a review of a large amount of scientific literature and final reports from similar test work on related raw materials. Based on this research, TUKE selected several and tested flotation reagents at different dosage levels. Then developed an experimental plan to explore various reagent types and dosages, combined with adjustments in pH, temperature, and slurry density.
At the same time, other processing methods were explored. Gravity separation tests, using a shaking table and a KNELSON centrifugal separator, showed that the ore could be successfully enriched using gravity-based methods and might be a good preparatory step before flotation. Finally, magnetic separation tested using both wet and dry methods, added another layer of flexibility to the processing strategy.
For the upcoming pilot-scale trials, the flotation circuit has been designed with adaptability in mind. The equipment is modular, allowing several possible flotation circuit configurations. However, since the reagent system and exact flotation procedure are still being optimised, the full pilot test has not yet been carried out.
One of the biggest challenge aspects so far has been identifying the right flotation collector, especially obtaining one specific type that is currently difficult to source. After overcoming this obstacle, the project is now moving steadily toward its next milestone: running the first test with the ore from the FEN deposit. This will mark a significant advance in developing a reliable processing flowsheet for the deposit.
