Cobra Resources plc (LON: COBR) Exceptional Metallurgical Results From Large Scale ISR Column

Results indicative of further reduced costs and increased production capacity

Cobra (LSE: COBR), a South Australian mineral exploration and development company, is pleased to announce highly favourable results from metallurgical studies on a large 55kg column sample from the Boland Ionic Rare Project (“Boland”) subjected to in situ recovery (“ISR”) conditions. The tests were carried out in collaboration with the Australian Nuclear Scientific Technology Organisation (“ANSTO”).

Highlights

·    Rapid recoveries enabled by high permeabilities – a highly favourable orebody characteristic for ISR

·    In just 17 days, the study achieved the following favourable results using 0.3 molar, (NH₄)₂SO₄ AMSUL targeting pH3:

·    68% Terbium (Tb)

·    63% Dysprosium (Dy)

·    62% Samarium (Sm)

·    57% Neodymium (Nd)

·    51% Praseodymium (Pr)

All achieved at very low acid consumption of just 3.88 kg/t

·    Recoveries are from a 55kg bulk composite sample taken from intervals of mineralisation from three sonic core holes yielding a head grade of 1,194ppm TREO (252ppm Nd+Pr and 33pm Dy +Tb)

·    Owing to the high permeability of samples, the test was executed at pressure of 2 bar where the average permeability rate was 2.1m/day

·    Post test completion, the pressure was increased to 5 bar, to reflect the Boland aquifer, where a permeability rate of 8.72 m/day was achieved

·    Preparations are underway to perform in-field permeability tests that aim to emulate the permeability rates achieved in this study – regulatory EPEPR approval received; a discharge permit is expected shortly that will enable the commencement of field testing

·    Further testing is ongoing to optimise the flow sheet, with results pending for:

o  Sulphuric acid generation – tests aiming to maximise the natural generation of acid from organic pyrite within the ore body that can materially reduce acid requirements – a primary operating cost of any Rare Earth operation

o  Cerium and Lanthanum reduction from generated pregnant liquor. Cerium is an abundant REE of low value – through additional testing Cobra aims to maximise product payability by maximising the proportions of Dysprosium and Terbium

·    Mixed Rare Earth Carbonate (“MREC”) to be produced from the optimised flowsheet – subsequent MREC product to be tested by prospective offtake parties                                                                                                   

Rupert Verco, Managing Director of Cobra, commented:

“Christmas has come early with these results; they have confirmed our belief that the permeability of our first bench scale study was impacted by a small quantity of saprolite being incorporated in the sample. As a result, the study took 150 days to achieve 68% recoveries. We have achieved similar recoveries in just 17 days and at a lower molarity. This means reduced costs and increased production capacity.

From a recovery standpoint, we now have complete confidence in the ionic recoverability of Boland ore and it’s now up to the team to demonstrate the ISR process in the field. Should we replicate these permeabilities in field testing, the commercial, environmental and strategic benefits of the Boland discovery will be undisputable.

We are looking forward to completing the acquisition of tenements EL6742, 6774 and 6780 so resource focused drilling can continue to demonstrate the significant scale of the opportunity that aims to deliver low-cost and sustainable critical minerals over a multi-generational mine life.

Updated Chinese export restrictions highlight the need for cost effective, reliably sourced heavy rare earths enabling emerging supply chain resilience. Cobra is advancing a strategy to address market needs for a sustainably sourced, refined heavy rare earth carbonate and the results of this study highlight the Boland Project’s ability to meet this demand.”

Scaled ISR Testing Results

·    Testing of (NH₄)₂SO₄ “AMSUL” diagnostic leaches below the industry standard of 0.5 molar (M) highlight that acid requirements can be even further reduced by lowering the lixiviant molarity. The completed column test used a diluted acidity of 0.3M targeting a pH endpoint of pH3

Due to the highly permeable nature of the sample, the increase in acidity occurred rapidly, reducing the column’s pH to ~4.1 where it stabilised. An increase in the acid dosage took the pH beyond the final set point before levelling out at pH3

·    REE recovery commenced almost instantly with 11.1% of REEs recovered before the acidity dropped below pH 4.1. Recoveries increased rapidly once the column pH reduced (increased acidity) below pH4

Figure 1. Graphed cumulative recoveries from the column over 17 days with associated acidity

 Figure 2: ISR column setup containing 55kg of Boland ore

 Study results support favourable projects economics with:

·    Very high recovery of valuable and strategically important Heavy Rare Earths (“HREO”) being 66.3% achieved using a low molarity 0.3M pH3 AMSUL lixiviant

·    Rapid recoveries enabled with high permeabilities which is a catalyst of ISR productivity

·    Very low acid consumption of 3.88 kg/t which is a significant reduction from the 15 kg/t used in the previous high grade ISR column

·    Breakdown of pyrite during the ISR process contributes to acidity. Owing to this unique trait for an ionic REE orebody, further tests are underway to determine how much acid can potentially be generated through ISR. Results anticipated soon

·    Low levels of radionuclides and impurities recovered, making impurity removal simple and cost effective

Table 1: Full results of ISR column test

Recoveries exceeding 100% are a result of ground water salinity contributing to the overall quantity of Ca, Mg and Na

Next Steps

The purpose of this ISR column has been to:

1.    Validate the permeability achieved in previous tests at a greater scale

2.    Optimise an already low-cost flowsheet that produced a high grade MREC by:

a.    Maximising the proportion of Dysprosium and Terbium in the final product

b.    Reducing the quantity of low value REEs: Ce and La

c.     Reducing the quantity of acid required

3.    Produce adequate MREC for offtake analysis

4.    Provide confidence to metallurgical inputs into economic analysis

Following this successful testwork, the following next steps outline the Boland workstreams and anticipated timeframes:

Metallurgical Optimisation:

·    Acid generation studies aimed at reducing the acid required to recover REEs: 1-2 weeks

·    Ce and La reduction: 2-3 weeks

·    Impurity removal: 3-4 weeks

·    Product quality: 4-6 weeks

·    Outcomes of offtake testing: 3-12 months

Field Studies:

·    Pump and tracer permeability studies: Planned to commence later this month once the final discharge permit is received, results within 3-6 weeks

·    Infield pilot study: 6-12 months

·    Environmental baseline and impact assessments: ongoing

Tristar Acquisition

·    Transfer of Native Title Mining Agreement (NTMA) – in process

·    Transfer of Tenure (Acquisition completion) (contingent upon the above) – Expected to take 1-3 months

·    EPEPR Submission (contingent upon the above) – Expected to take 1-2 months

Resource & Project Economics

·    Boland extensional drilling (late November – December)

·    Regional Drilling (contingent upon the completion of the TriStar acquisition)

Boland Project

At Boland, Cobra has discovered what it believes to be a unique, scalable instance where ionic rare earth elements – containing economically attractive grades of valuable heavy and magnet rare earths – occur in a permeable horizon confined between horizons of impermeable clay.

Bench scale ISR testing has confirmed that this mineralisation is amenable to ISR recovery techniques. ISR techniques are currently in use (and have been used successfully for decades) in geologically similar environments, to recover uranium in South Australia which maintains a well-established ISR regulatory system.

Results of Cobra’s ongoing mineral recovery test work indicate that, with minor optimisation, ISR techniques will enable non-invasive and low-cost production of critical REEs from its discovery at Boland.

Follow this link to watch a short video of CEO Rupert Verco explaining the results released in this announcement: https://investors.cobraplc.com/link/PGqZle

Further information relating to Boland and these results are presented in the appendices.

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