Aton Reports New Results from Metallurgical Testing on Rodruin and Hamama West Sulphide Mineralisation

VANCOUVER, BC / ACCESSWIRE / July 28, 2023 / Aton Resources Inc. (TSXV:AAN) ("Aton" or the "Company") is pleased to update investors on the results of further preliminary metallurgical testwork from its Rodruin and Hamama West projects. Rodruin and Hamama West are both located within the Company's 100% owned Abu Marawat Concession ("Abu Marawat" or the "Concession"), in the Eastern Desert of Egypt.

Highlights:

• Two composite samples representing the main sulphide mineralisation types at Rodruin underwent preliminary metallurgical testwork investigating the potential to produce saleable copper and zinc concentrates. The composite samples were prepared from selected diamond drill half core intervals;
• Results from a locked cycle flotation test carried out on sample ROMS-007 produced a copper concentrate of 28.1% copper at a recovery of 69.2%, and a zinc concentrate of 61.6% zinc at a recovery of 79.6%;
• Sequential flotation tests carried out on the Rodruin sulphide mineralisation types indicate that potentially saleable copper and zinc concentrates can be achieved at reasonable metal recoveries and grades. Both the copper and zinc concentrates contain reasonable gold and silver credits;
• A single bulk composite sample representative of the sulphide mineralisation at Hamama West underwent metallurgical testwork including cyanidation leach testing and flotation testwork to assess its amenability to cyanide leaching, and the potential to produce a saleable gold- or gold-silver bearing concentrate. The composite sample was prepared from selected diamond drill half core intervals and RC percussion drill chips;
• Whole ore cyanide leach testwork showed that 49.8% of the gold was recoverable by cyanide leaching. Metal recoveries of 47.1% and 26.1% were also obtained for silver and copper, respectively;
• Rougher flotation optimisation found that 81.2% and 75.7% of gold and silver were recoverable to a concentrate, at grades of 3.41 g/t gold and 84.8 g/t Ag silver, and at a high mass pull of 25.5% by weight;
• A bulk sulphide float recovered 85% of the gold and 83% of the silver to a rougher concentrate assaying 2.98 g/t Au and 94.9 g/t Ag, respectively;
• Bulk concentrate cyanide leach testwork showed that a gold recovery of 54.8% was achievable at a particle size of 80% passing 10µm. Silver and copper recoveries of 60.3% and 47.0% were achieved, respectively;
• The Hamama West sulphide mineralisation was not amenable to conventional CIL, nor flotation followed by ultra-fine grinding/CIL processing routes. A bulk sulphide float produces a potential precious metals concentrate containing gold and silver credits.

"These preliminary metallurgical testwork results from the Rodruin gold-polymetallic sulphide mineralisation are most encouraging, and indicate that saleable copper and zinc concentrates can be produced, containing very respectable gold and silver metal credits. The copper concentrate in particular recovers high grades of gold and silver, and could potentially be sold as a precious metals concentrate" said Tonno Vahk, Interim CEO. "The results from testing of the Hamama West sulphide mineralisation were less positive and indicate that the sulphide mineralisation is refractory, and is not amenable to CIL processing. However high recoveries of gold and silver to a bulk concentrate indicate that a precious metals concentrate could potentially be produced from Hamama West, and this could provide Aton with some synergies when processing sulphide material from both the Hamama West and Rodruin deposits, as well as the higher grade Abu Marawat deposit, which contains significantly higher copper grades than either Rodruin or Hamama West. In the light of the results from this phase of metallurgical testwork Aton has decided to defer the immediate work on the revised mineral resource estimate for the Abu Marawat Concession, as it evaluates a net smelter return approach to the resource estimation, in order to fully assess the potential of the Hamama West, Rodruin and Abu Marawat gold-silver-copper-zinc sulphide deposits. The Company is continuing to push ahead towards its immediate primary goal, which is the completion of its application for the exploitation licence at the Abu Marawat Concession, and plans to submit this application to the Egyptian Mineral Resources Authority within the coming two months. The application for the exploitation licence will be based on a ‘commercial discovery' comprising open pit mine and heap leach projects on the oxide gold caps of both the Hamama West and Rodruin deposits, which will represent the first two mining projects in the planned phased development of the Abu Marawat Concession."

Metallurgical testwork programme - Rodruin

Two composite samples were prepared from the Rodruin mineral deposit for metallurgical testing, which were representative of the two main sulphide mineralisation types, hosted in intensely phyllic altered ("phyllic") and carbonate rock types. This preliminary testwork programme was designed to follow on from testing of the oxide mineralisation types carried out in early 2023, which indicated that the Rodruin oxide mineralisation is amenable to processing using heap leach and conventional CIL technology (see news release dated March 9, 2023). The programme was specifically focused on the sulphide mineralisation at Rodruin to evaluate the potential of processing both the main sulphide mineralisation types by flotation, with the goal of producing saleable copper and zinc concentrates.

Samples were selected from diamond drill half core intervals (HQ and PQ size), to produce total sample weights between 40-45kg. 2 samples were composited from the 2 main sulphide mineralisation types, specifically phyllic and carbonate hosted mineralisation (see Figure 1). Details of the samples are provided in Table 1.

Table 1: Details of the Rodruin sulphide metallurgical samples

The diamond drill half core samples were dispatched from Egypt to Wardell Armstrong International Ltd ("WAI") in December 2022, for metallurgical testing at their laboratory located in Cornwall, UK, with testwork commencing in January 2023. The half core intervals were combined to prepare 2 composite samples, which underwent a process evaluation testwork programme consisting of head assays, XRD analysis, rougher, cleaner and locked cycle flotation testing.

Head assays

Sub-samples of the 2 composite metallurgical samples were sent by WAI for head assay analysis at ALS Minerals' geochemical laboratory at Loughrea, Ireland, and were analysed for Au (by screen fire assay), Ag, Cu, Pb, Zn, As, Fe and S. Additional analysis for deleterious elements was not undertaken, but this additional analytical work is planned. The results of the head assays are provided below in Table 2:

Table 2: Head assay results

The Au head assays measured by screen fire assay show good correlation with the estimated grade of the composited drill core samples (Table 2). Ag, Cu, Pb and Zn head assays also showed good correlation with the estimated grades of the composite samples.

The good correlation in assay results indicates that the composited samples prepared for metallurgical testwork are representative of the drill core intervals sampled.

Mineralogical analysis

The XRD results showed the samples as being gangue dominated. The phyllic hosted ROMS-006 composite sample is predominantly composed of quartz, phyllosilicate minerals (chlorite, illite, mica) and pyrite. The carbonate hosted ROMS-007 composite sample contained a mixture of dolomite, talc, quartz and pyrite. Sphalerite occurs as a minor but significant constituent of both samples.

The results of the XRD analysis are shown in Figure 2:

Flotation testwork - Rodruin

Rougher optimisation tests

The two sulphide samples were subjected to flotation testing to investigate the potential to recover base metal concentrates from the sulphide mineralisation.

The flotation route tested involved sequential copper and zinc flotation. A primary grind size of 80% passing 75μm was utilised for rougher flotation optimisation, except for ROMS-006 FT3 where a grind size of 80% passing 53µm was used. Results are summarised in Table 3.

Table 3: Optimal rougher flotation test results

Rougher optimisation testwork showed optimum copper and zinc recoveries to concentrates from the ROMS-006 sample were 87.9% at a grade of 2.32% copper, and 62.6% at a grade of 16.0% zinc, respectively. For the ROMS-007 sample optimum flotation performance achieved recoveries of 87.4% at a grade of 3.54% copper, and 91.5% at grade of 9.95% zinc, respectively.

Open cycle cleaner tests

A series of open circuit cleaner flotation tests were subsequently conducted based upon the optimum rougher flotation conditions. A summary of the optimum open circuit results is provided in Table 4.

Table 4: Open cycle cleaner test results

Three-stage open circuit cleaner optimisation testwork demonstrated that for sample ROMS-006, final concentrate grades of 32.3% copper at a recovery of 54.0%, and 52.2% zinc at recovery of 63.9% could be achieved, respectively. Furthermore, gold and silver were recovered to the final copper concentrate at grades of 103 g/t Au and 1,512 g/t Ag, respectively.

The same three-stage cleaning conditions were utilised for sample ROM-007, from which final concentrate grades of 34.9% Cu at a recovery of 42.4%, and 50.3% Zn at a recovery of 67.3% were achieved, respectively. Gold and silver were recovered to the final copper concentrate at grades of 32.4 g/t Au and 1,012 g/t Ag, respectively.

Locked cycle tests

A single locked cycle test was carried out on the ROMS-007 sample, as the predominant lithology of the two sulphide mineralisation samples, based on the test conditions used in the FCT5 open cycle cleaner test. A summary of the flotation performance as an average of the final three cycles is shown in Table 5.