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Charger Metals NL (ASX:CHR) has announced outstanding initial metallurgical outcomes from Stage 1 crushing and ore sorting testwork at its Medcalf deposit, part of the fully owned Lake Johnston Lithium Project in Western Australia. The findings reveal an increase in lithium oxide grades from 1.01% to 1.32% Li2O—a 31% enhancement—while attaining a Recovery Rate of 94.9%, along with a notable decrease in harmful iron content. These results follow the company’s recently updated Medcalf Mineral Resource Estimate, which expanded by 34% to 10.6 million tonnes at 1.0% Li2O, as Charger prepares to advance the project through additional drilling and processing studies funded by the recent divestment of its Bynoe Project.
Key Points
- Company: Charger Metals NL (ASX:CHR)
- Stage 1 metallurgical testing at Medcalf deposit, Lake Johnston Lithium Project, Western Australia, delivers strong ore sorting outcomes
- Li2O grade increased from 1.01% to 1.32% (31% uplift) with 94.9% lithium recovery; Ta2O5 grade rose from 109ppm to 147ppm (34% uplift) with 97.2% tantalum recovery
- Iron content reduced to 1.27%, equating to rejection of 78% of total iron units from feed
- Medcalf Mineral Resource Estimate recently revised to 10.6Mt at 1.0% Li2O and 107ppm Ta2O5 — a 34% increase from the maiden resource published about 10 months ago
- Average Bond Crushing Work index of 7.55 kWh/tonne, classified as moderate hardness
- Four spodumene concentration plants located within trucking distance; Esperance Port approximately 200 kilometres away
- Investors to monitor Stage 2 metallurgical testing, including Heavy Liquid Separation (HLS) targeting further iron removal, plus progress on Mining and processing studies
Medcalf Stage 1 Ore Sorting Yields 31% Lithium Grade Enhancement and 94.9% Recovery
Charger Metals’ Stage 1 metallurgical program at the Medcalf pegmatite deposit has produced results described by the company as excellent, with TOMRA’s X-Ray Transmission (XRT) ore sorting technology effectively upgrading lithium oxide content while retaining the majority of lithium. The Master Composite, with a calculated head grade of 1.01% Li2O and 109ppm Ta2O5—closely matching the revised Medcalf resource grade of 1.0% Li2O and 107ppm Ta2O5—was crushed, screened, and sorted at Independent Metallurgical Operations and TOMRA’s Sydney Facility.
Combining the -10mm fines fraction (not subjected to ore sorting) with the sorted +10mm and +25mm concentrate fractions resulted in an overall Li2O grade of 1.32%, lithium recovery of 94.9%, and mass recovery of 72.5%. The tantalum oxide grade increased to 147ppm with 97.2% recovery, while iron grade dropped sharply to 1.27%, indicating approximately 78.3% of total iron units were rejected as waste. These findings confirm the material’s suitability for XRT-based ore sorting technology, a critical factor for the project’s Economics.
TOMRA’s XRT Technology Effectively Separates Spodumene Pegmatite from Amphibolite Waste at Lake Johnston
Testwork by TOMRA Sorting|Mining leveraged the density contrast between basalt and pegmatite to sort mineralised Medcalf material. Samples were screened into two size fractions—25–50mm and 10–25mm—each sorted separately using TOMRA’s COM X-Ray Transmission (XRT) system. The primary goal was to produce a low-iron product by ejecting high-density basalt, with a secondary aim to maximise lithium recovery across both fractions.
The 25–50mm fraction showed feed grade of 0.96% Li2O upgraded to 1.31% Li2O, a 37% increase, with 69% mass recovery and 86% lithium recovery. The 10–25mm fraction performed similarly, upgrading from 1.02% Li2O to 1.43% Li2O (41% increase), with 66% mass recovery and 86% lithium recovery. The company noted minimal difference between size fractions, attributing this to excellent liberation characteristics of Medcalf material—an encouraging sign for processing consistency.
Combined +10mm Sorted Concentrate Achieves 1.37% Li2O and 159ppm Ta2O5
The combined +10mm and +25mm sorted concentrate, representing about 58% of total mass tested, attained grades of 1.37% Li2O and 159ppm Ta2O5, with recoveries of 78.4% and 83.6% respectively. Iron grade in this concentrate dropped significantly to 0.67%, compared to the initial composite feed grade of 4.23% Fe. This iron rejection is notable given that elevated iron can negatively impact Downstream processing and product quality.
The -10mm fines fraction, not ore sorted, contained 16.5% of total lithia at 1.12% grade and 12.6% of total iron at 3.59% grade. When recombined with the sorted concentrate, the overall lithium grade was 1.32% with 94.9% recovery, and tantalum oxide grade was 147ppm with 97.2% recovery—results the company describes as highly promising for project development. Heavy Liquid Separation (HLS) testing planned next will aim to further reduce iron content.
Bond Crushing Work Index of 7.55 kWh/Tonne Indicates Moderate Hardness at Medcalf
In addition to ore sorting, crushing testwork provided insights into Medcalf pegmatite’s physical properties. Twenty rock samples from the -50+25mm fraction of the Master Composite underwent Bond Crushing Work Index (CWi) testing, crushed to P100 19.0mm, followed by Abrasion Index (Ai) testing. The average CWi was 7.55 kWh/tonne with a median of 7.26 kWh/tonne, classifying the material as moderately hard.
The Abrasion Index measured 0.302, also moderate. Average specific gravity was 2.75 and impact energy averaged 24.68 joules. These parameters have important implications for engineering and Capital costs, as moderate hardness typically results in manageable comminution expenses and supports economically viable throughput rates. No specific processing cost estimates were disclosed.
Medcalf Mineral Resource Grows 34% to 10.6Mt at 1.0% Li2O in Ten Months
These metallurgical results complement a recently upgraded Mineral Resource Estimate for the Medcalf spodumene deposit. As detailed in the company’s 23 June 2026 update, the Medcalf lithium Inferred Mineral Resource increased to 10.6 million tonnes at 1.0% Li2O and 107ppm Ta2O5, a 34% rise from the maiden resource published about 10 months earlier. The lithium MRE uses a 0.4% Li2O cut-off, while the tantalum MRE applies a 65ppm Ta2O5 cut-off.
Managing Director Bryan Dixon expressed confidence that further drilling will expand the resource, which remains open down dip and along strike. The resource size, combined with positive metallurgical characteristics, positions Medcalf as a significant deposit within Lake Johnston, though no formal economic studies or production guidance have been issued yet.
Bryan Dixon Highlights Ore Sorting’s Role in Managing Dilution in Medcalf’s Stacked Pegmatites
Mr. Dixon noted that ore sorting results give Charger confidence that most mining dilution from stacked pegmatites at Medcalf can be removed effectively using ore sorting technology. This is important because stacked pegmatite systems often face dilution challenges from interbedded waste rock such as amphibolite, which can lower processing feed grades.
He also mentioned that the recent sale of the Bynoe Project provides funding for further drilling and mining and processing studies to assess the economics of Lake Johnston. The company did not disclose proceeds from the Bynoe sale or timelines for economic studies. Investors will likely seek updates on funding and work programs in future reports.
Proximity to Four Spodumene Concentration Plants and Esperance Port Supports Processing Options
A key strategic advantage for the Lake Johnston Lithium Project is its infrastructure setting. Charger highlighted that four spodumene concentration plants are within trucking distance, offering potential near-term processing options without the need to build a new facility. This toll-treatment potential is expected to be considered in upcoming mining and processing studies.
The announcement also noted that shipping ore sorted concentrate is feasible, with Esperance Port located about 200 kilometres by road. Depending on study outcomes, shipping pre-upgraded, ore-sorted concentrate could provide a direct-shipping route before or alongside regional processing arrangements. These logistics contribute to project viability, though no binding agreements or offtake deals were disclosed.
Stage 2 Metallurgical Testing and HLS to Drive Next Phase at Lake Johnston
Following Stage 1 results, investors and analysts will watch the progression of Stage 2 metallurgical testing at Medcalf. The company plans Heavy Liquid Separation (HLS) testing aimed at further iron removal from the ore-sorted concentrate. Since iron was already reduced from 4.23% in feed to 1.27% in sorted product during Stage 1, additional iron rejection via HLS would enhance product quality.
Other key milestones include ongoing drilling to test resource extensions, completion of mining and processing studies to formalize project economics, and announcements regarding processing partnerships with regional spodumene plants. The immediate market impact of Stage 1 results was not evident at publication.
Lake Johnston Project Advances Amidst Volatile Global Lithium Market
The Medcalf metallurgical outcomes come amid significant volatility in the global lithium market, with spodumene concentrate prices having declined substantially from peaks in 2022 and 2023. In this environment, the ability to demonstrate strong ore sorting—enabling grade uplift, mass reduction, and iron rejection before downstream processing—may be especially important for project economics by reducing processing volumes and improving product quality and competitiveness.
Charger Metals is in the early stages of technical development at Lake Johnston, now supported by a 10.6Mt Inferred Mineral Resource, confirmed ore sorting amenability, and a defined program including HLS testing and economic studies. The company has yet to publish a Scoping Study, Preliminary Feasibility Study, or formal economic analysis. Investors should note that Inferred Mineral Resources carry inherent geological uncertainty. While this announcement marks significant technical de-risking, the project remains pre-development with further studies needed before production or economic decisions can be made.
