Arcadia Minerals Ltd. announced positive mineralogical and processing results from Bitterwasser Lithium-in-Clay ores. Multotec Process Equipment (Pty) Ltd. was appointed by Arcadia to conduct cyclone test work on 800kg Bitterwasser representative clay samples from the Eden Pan. The aim of the program was to identify if the fine clay fraction of < 10 fraction, could be separated from the remaining larger material that consist mainly of calcite, dolomite and quartz, and by doing so, the lithium grade in the feedstock material could be increased.

The composite 800 kg auger drilled core sample represents a clay sample combining all the different zones (both the brown and green clay) and from all the boreholes drilled as part of the 2022 drilling campaign. This sample is regarded a truly representative sample of the Eden Pan clays covering the complete stratigraphy from surface to approximately twelve meters below surface. After the sample was received by Multotec, the material was blended, and a representative sub-sample was taken to be analysed for particle size distribution (PSD) through a Malvern master-sizer, and specific gravity (SG) through a pycnometer for the PSD results.

The SG of the material was measured to be 2.4 t/m3. Based on the PSD, SG as well as the pulp relative density (RD) information, the following cyclone configuration was simulated: An FC40 cyclone with 5° cone and 1 barrel was tested. The operating pressure was kept constant at 105kPa.

The cyclone sump was filled with water up to 500 litres. The stirrer and cyclone pump were then started with the feed bypassing the cyclone. The sample was gradually added to the sump.

The RD of the feed was measured, and water was added to obtain the desired feed RD's for the test work. Once the desired RD's of the feed slurry were obtained, it was sampled three times (referred to as the actual feed). The main valve was opened while closing the bypass valve, where the feed slurry was then fed through the cyclone at the operating pressure as per the simulation.

The spigot is optimised by changing the size until optimum flaring is achieved. Once the spigot was properly optimised, the cyclone was allowed to run for 10 minutes to reach steady state before commencing with the RD measurements of the overflow and underflow streams. The necessary RD checks were done and were repeated three times to ensure consistency and repeatability. The cyclone was allowed to reach steady state before sampling the overflow and underflow streams three times (the cyclone products).

All the samples collected were prepared to complete the mass balance and the associated PSD analyses and chemical analyses. The cyclone results indicated that 30.4% of the feed material reported to the underflow (coarse material) and 69.6% of the material to the overflow (fine material). The overflow is showing a cumulative % passing 10µm of 96.9%, which states that majority of the -10µm material is reporting to the underflow stream.

The cyclone test work therefore indicates that if a 14-micron cut size is used, about 70% of the material would report to the overflow and around 97% of this overflow material would be below 10 microns. Multotec sent the three feed, overflow and underflow samples from the steady stage cyclone products to UIS Analytical Services in Pretoria, South Africa for ICP-OES analytical analyses. From the results it is observed that the underflow sample resulted in a 27.9% increase in the grade compared to the ore fed sample.

The cyclone test work has therefore confirmed that using a 14-micron cut off, the cyclone overflow results in a 30% reduction in volume with a concomitant increase of 28% in the lithium grade compared to the ore material. Total lithium recovery could be 89.6%. Cyclones could therefore be a viable option to increase the Bitterwasser clay deposit grades before leach take place.

Arcadia is currently working in conjunction with the Chemical Engineering Department of the University of Stellenbosch on a bulk-scale test work program that includes testing various acid doses, temperatures and leach times using six different organic acids and sulphuric acid as the baseline. The test work could result in the optimisation and potential increase in the leachability of Bitterwasser ores. At the end of the program the most promising acid would be selected to test 100kg of cyclone concentrate (produced by Multotec) for leachability and the production of Lithium carbonate.

Initial leach test work was conducted using six organic and sulphuric acids. Four test cycles were completed for each acid. Two cycles at room temperature were done using no oxidants and 1% vol H2O2.

Organic acid 1 followed a very similar trend to that of Sulphuric acid at 25C but outperformed sulphuric acid at 60C and 1 hour leach time. The organic acid exhibited leach recoveries of82% of the lithium within 1 hour at a temperature of 60C. The second phase of leach test work is currently underway and will include various acid doses, varying PH's, temperatures and leach resident times.

Based on these results an acid will be selected to conduct bulk leach test work.