o High quality commercial grade separate concentrates achieved: zinc (54-59%), and lead (47-64%).
o Excellent zinc recoveries: 87-92% - the dominant base metal of the deposit.
o High combined recoveries for silver (75-85%) and gold (66-90%).
o Kempfield repositioned as an economically viable polymetallic project with zinc, silver, lead and gold revenue streams from separate saleable zinc and lead concentrates.
o Industry standard flotation process design for potentially favourable capex and opex.
o Drilling to proceed as the top priority.
The extraction of zinc and lead into separate concentrates marks a significant advance towards project development, as the Company pursues the redefinition of Kempfield as an economically viable polymetallic project with multiple revenue streams at prevailing market prices.
Under the project redefinition validated by today's results, zinc becomes the major contributor to potential revenue, followed by silver, lead and gold - substantially boosting the economics and de-risking the project.
In addition to potentially taking advantage of favourable market conditions for zinc producers, the polymetallic scenario retains significant upside leverage to any future silver price escalation that may occur.
About the metallurgical test results
The following results were achieved by a flotation test followed by the regrinding of lead rougher concentrates and conducting a series cleaning tests for separate lead and zinc flotation circuits:
Table 1 - Metallurgical test results summary (1)
Grade Recovery Zinc 54-59% 87-92% Silver Up to 977 g/t 75-85%(2) Lead 47-64% 44-53%(3) Gold Up to 16 g/t 66-90%(2)
1. The results are displayed in approximate decreasing order of each metal contribution to potential revenue, from the highest (zinc) in the top row of the table;
2. Silver and gold grades and recoveries depend on the final flowsheet design, and optimisation for prevailing commercial conditions; several potential concentrate product take-off points are provided by the tested process flowsheet.
3. Further potential process improvements have been identified for increasing lead recoveries, for incorporation into ongoing testwork.
About the quality of the concentrates
The achieved zinc and lead grades are considered to be high grade in the context of the typical industry-accepted guideline of the order of 50% concentration, and comfortably within publicly reported historical smelter contract requirements.
The commercial impact of deleterious elements is estimated to be very low with penalties estimated to be zero for the lead concentrate and less than 1.3% of the total potential net smelter revenue (NSR) for the zinc concentrate.
Based on these metallurgical test results (and subject to further metallurgical testing), Argent's project modelling indicates that production concentrate silver grades could be up to four times the grades reported in Table 1. This is because the available drill core suitable for making the metallurgical testwork composite sample had approximately a quarter of the average silver grade of the Kempfield deposit.
Capex and opex benefits - industry standard process design
The test results also showed that:
o Optimum commercial performance is achievable by a relatively simple process.
- Whilst the performance of product from different stages of the process was evaluated, the optimum commercial result (after taking into account smelter terms and conditions assumptions) is estimated to be provided by the 1st cleaner stage for both the zinc and lead concentrates - a relatively simple process design implying reduced process plant capital expenditure requirements.
- Argent's modelling of the above scenario indicates potential revenue stream contributions to NSRi comprising zinc (45%), silver (36%), lead (11%), and gold (8%) - at recent market pricesii and the Company's estimates for smelter contract terms and conditions based on available information.
o Primary grind particle size well within industry peer process plant design practice.
- Whilst the tests included a primary grind size down to P80 = 40 µm, the results showed that P80 = 53 µm was sufficient for achieving the target concentrate grade and recoveries, implying reasonable electrical power requirements.
- a lead rougher concentrate regrind particle size distribution of P80 = 15 µm was sufficient to produce the lead 1st cleaner concentrate. The design required only 2.6% (by weight) of the feed material to be reground for further refinement.
Next steps for metallurgical testing
The next steps for metallurgical testing are envisaged to include variability testing across the various mineralogical domains of the Kempfield deposit. This will require additional samples to be collected. The metallurgical engineer has prescribed a highly cost-efficient method based on collecting samples from reverse circulation (RC) drilling and protecting the samples from oxidation by storage within nitrogen-filled containers prior to freezer storage at the metallurgical laboratory facilities. This method has been determined by the metallurgical engineer as appropriate for the current stage of the Kempfield project, avoiding the need for costly dedicated metallurgical diamond drilling whilst making use of samples obtained for exploration and resource infill drilling.
Drilling to proceed as the top priority
Following its review of the Company's projects, the Argent board has determined that drilling is to proceed at Kempfield as the top priority.
Planning is underway for an initial drilling programme, the design of which is guided by the new geological model and the Company's internal project economics model that has been updated based on today's metallurgical results.
The drill plan and strategy will be announced separately to the ASX on completion of the design work.
To view tables and figures, please visit:
About Argent Minerals Limited
Argent Minerals Limited (ASX:ARD) is an Australian publicly listed company with a 100% interest in a silver/gold project at Kempfield NSW. Work is underway on the preparation of an EIS and a feasibility study for the first stage of the project which will involve heap leaching some 8.8 million tonnes of mainly oxide and transitional material to produce over 9.5 million ounces of silver and 15,000 ounces of gold over a 5 year mine life. Argent is also earning up to a 70% interest in two other NSW projects - gold at West Wyalong and base metals at Sunny Corner.
Chief Executive Officer
Argent Minerals Limited
M: 0415 613 800