London-listed resource exploration and development company Altona Rare Earths has reported that initial flotation rougher test results received for its Monte Muambe rare earths and fluorspar project, in Mozambique, Test F5, show a high rare earths recovery of 69.3% and good selectivity of rare earth minerals compared with fluorite.

The company says these results provide a positive pathway for further optimisation of flotation parameters, adding that a review of the Monte Muambe project's potential for fluorspar production has begun, including the possible short-term production of metallurgical-grade fluorspar from low-tonnage high-grade hydrothermal fluorspar veins.

These fluorspar veins have legacy drilling intercepts of up to 10 m at 54.77% calcium fluoride (CaF₂) and trenching intercepts of up to 16 m at 71% CaF₂.

Moreover, the company has reported that the presence of sediment-hosted copper mineralisation 4 km east of its Kabompo South licence has been visually confirmed by the company's CEO during a recent site visit.

Altona’s Kambopo South copper project is located in Zambia.

The company adds that a geophysical consultant has been engaged to reprocess and review legacy geophysical data as well as the diamond potential for Kabompo South.

MONTE MUAMBE METALLURGY

Altona says mineralogy and partial flotation rougher test results have been received from metallurgical testing and analytical services provider SGS Lakefields.

Froth flotation is a standard separation method for minerals from milled ore, and rougher flotation is the first stage of concentration.

Altona says mineralogical testing has confirmed that rare earths are mostly contained in rare earths fluorocarbonates – bastnaesite, parasite and synchisite –  71% by weight, monazite 18%, and other rare earths minerals 11%.

A range of flotation parameters and reagents were tested. The best results were obtained with test F5, which showed a good selectivity of rare earths minerals compared to fluorspar, and a recovery of 69.3% for rare earths.

The company says results obtained so far provide a clear pathway for further optimisation of flotation parameters, which will take place over the coming weeks.

“Flotation parameters are particularly important at Monte Muambe as an increase of the rare earths concentrate grade considered in the scoping study is expected to significantly reduce the capital and operational expenditure of the downstream hydrometallurgy process,” says Altona.

MONTE MUAMBE FLUORSPAR PRODUCTION POTENTIAL RE-ASSESSMENT

Since 2021, the company's exploration work at Monte Muambe has been focused on its rare earths deposits.

Monte Muambe, however, was originally known for its fluorspar potential, and legacy mineral exploration activities were largely focused on this mineral.

Considering the currently depressed prices of rare earths, the company says it considers that reassessing the economic potential of associated minerals is a “prudent course of action.”

Fluorspar is encountered in two forms at Monte Muambe: as disseminations in rare earth ore, and as hydrothermal veins lining the contact between carbonatites and fenites.

Assays of drilling samples obtained by Altona since 2021 have shown the ubiquitous presence of disseminated fluorspar in rare earths ore at Target 1 and Target 4, with a grade averaging 13.2% CaF₂ for samples having over 1.5% total rare earth oxide, and reaching as high as 70.45% CaF₂.

The representative rare earths ore sample sent to SGS Lakefields for metallurgical testing contains 16.8% CaF₂.

Besides the production of a rare earths concentrate, Altona says the objective of on-going metallurgical testwork at SGS Lakefields is also to assess the possible separation of a fluorspar concentrate by-product.

Legacy exploration work in the western part of the Monte Muambe carbonatite intrusion resulted in the definition of a historical Joint Ore Reserve Committee-compliant inferred mineral resource of 1.6-million tonnes at 19% CaF₂.

This estimate covers both disseminated fluorite and hydrothermal fluorite. A review of legacy drilling and trenching data shows that hydrothermal fluorite veins have a thickness ranging from 10 m to 20 m, with grades of up to over 70% CaF₂.

Fluorspar is an essential mineral used in many industries for its intrinsic properties and as the main source of the element fluorine.

Altona explains that fluorspar is identified by both the US and the EU as a critical mineral.

Fluorspar is crucial to the production of lithium batteries and manufacturing an electric vehicle requires about 45 kg of fluorspar. Hydrofluoric acid is also an essential input for the production of PV panels.

Since 2021, Altona notes that fluorspar prices have been steadily increasing, driven by a supply gap and dwindling reserves in China.

After reaching record prices in the third quarter of 2023, fluorspar prices currently stand at about $480/t, 40% higher than the average for 2021.

Analysts forecast a chronic demand-supply gap, with the US Department of Energy expecting demand to exceed supply by 40% to 70% by 2035.

As a result, Altona says it has decided to undertake an in-depth review of Monte Muambe's potential for fluorspar production.

Besides ongoing metallurgical testwork, the company will review legacy data, collect new samples and data on site in October, and prepare a conceptual study with a view of assessing the possible short-term production of met grade fluorspar from known high-grade hydrothermal fluorspar veins of the Fluorite zone.

"Metallurgy is the most challenging part of rare earths mining projects. Over the past months we have tremendously increased our understanding of the mineralogy and metallurgy of Monte Muambe, and I am very pleased with the testwork's progress. While more work is necessary, and will continue over the next weeks, results received so far show a clear path towards a viable beneficiation process and the production of a rare earths concentrate.

"The possible short-term production of fluorspar, another critical mineral, from Monte Muambe, is a very exciting possibility and challenge, which fits neatly in the company's strategy to diversify its portfolio of commodities and realise the value from its assets,” says Altona CEO Cedric Simonet.