DY6 Metals highlights potential for phosphoric acid-grade co-product at Tundulu in Malawi

• DY6’s preliminary testwork achieves high recoveries of >85% REE and >90% phosphate
• Work identifies opportunity to produce phosphoric acid-grade concentrate co-product
• Further testing to determine route to producing high-grade concentrates for processing

Special Report: Preliminary metallurgical testing of ore from DY6 Metals’ Tundulu rare earths and phosphate project in Malawi has identified the opportunity to produce a phosphoric acid grade flotation concentrate co-product.

The testing of the 120kg composite sample grading 1.88% total rare earth oxides and 9.07% phosphorus pentoxide from a high-grade historical trench demonstrated excellent phosphorus solubility of over 40% – with one test returning 81% solubility – during bioavailability testing using 2% citric acid.

This is well above the industry threshold of 9.4% P2O5 solubility using citric acid as the reagent in the acid leach process.

The elevated phosphate grades of the deposit are also amenable to being upgraded into a flotation concentrate, providing DY6 Metals (ASX:DY6) with the potential opportunity of developing a fast and cheap direct fertiliser product from the near-surface high grade phosphate zones within the deposit.

On the rare earths front, the company found the REE mineralogy in the sample closely resembles the mineralogy of Mkango Resources’ nearby Songwe Hill project, which supports regional metallurgical familiarity.

While flotation testwork carried out by DY6 to date has been limited, it believes that further testwork could deliver a concentrate grade suitable for treatment via a centralised hydrometallurgical plant.

“These preliminary metallurgical testwork results, while in no way exhaustive, are encouraging,” chief executive officer Cliff Fitzhenry said.

“The fine-grained nature of the dominant REE minerals (bastnaesite and synchysite) hosted within an apatite carbonate gangue has highlighted the need to undertake additional testwork to produce a high-grade concentrate suitable for processing within a hydrometallurgical plant.

“Additionally, the high phosphate grades lend a co-product phosphoric acid grade flotation concentrate opportunity.

“We are confident that, with carefully planned follow-up testwork we will be able to further unlock the significant co-product opportunity that exists at Tundulu.”

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Tundulu project

The 91.5km2 Tundulu project in southern Malawi comprises several hills in a ring around a central vent called Nathace Hill, where the majority of historical surface sampling and drilling has been undertaken and identified heavy REE mineralisation.

Exploration undertaken by Japanese International Cooperation Agency in 1988 drilling down to a depth of 50m included a hit of 41m at 3.7% TREO from 8m.

A subsequent 55-hole drill program totalling 7000m targeting various elevations on the eastern slope of Nathace Hill in 2024 defined several mineralised zones with assays topping up at 101m at 1.02% TREO and 3.6% phosphate.

The rare earth carbonatite shows the highest grades of REE whilst the other areas host mineral apatite and showed phosphate grades ranging from ~5-30% P2O5.

Sampling carried out by the company found mineral rich carbonatite at the previously unexplored Tundulu Hill and Makhanga Hill to the east and west of Nathace respectively.

Flotation testwork carried out on the concentrate collected by the company yielded promising results with >85% TREO and >90% P2O5 recoveries achieved.

However, this did not produce a high-grade concentrate due to the mineralogy and fine-grained nature of the target minerals.

That said, the reasonable high grades provide reassurance that flotation performance and concentrate grade can be improved with further work that will seek to confirm the most suitable reagents combination for the rejection of carbonate, iron and silica minerals.

Consultants have recommended that DY6 carry out a detailed mineralogical analysis using quantitative modal techniques such as QEMSCAN and TIMA.The company will also look to expand the beneficiation testwork program. The focus with that would be on ore preparation prior to flotation and start sighter concentrate, refining testwork to identify opportunities and any limiting factors associated with the Tundulu mineralisation.

This article was developed in collaboration with DY6 Metals, a Stockhead advertiser at the time of publishing.

This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.