Winston Tailings Sampling Underway

Panther Metals Plc (LSE: PALM), the exploration company focused on mineral projects in Canada, is pleased to announce the commencement of a tailings sampling programme at the Winston Project1, located on the historic Winston Lake Mine in Ontario, Canada.

This initiative marks a key step in assessing the potential to reprocess historical mine tailings, aiming to unlock residual metal value, extend project life, improve overall returns, and contribute to the long-term environmental rehabilitation of the site.

The Winston Lake Mine was operational from 1988 to 1998, producing approximately 3.3 million tonnes of ore and yielding zinc, copper, silver, and gold. Based on historic recoveries from mining activities in the 1980s and 1990s, it is believed that a significant quantity of valuable material remains in the tailing storage facility. Early analysis suggests that successful reprocessing could nearly double the known resource at the Winston Project.

Programme Objectives

The tailings focussed work forms part of Panther's strategy to unlock the value from the Winston Project's historical mine site while contributing positively to local environmental outcomes.

The current sampling programme, and associated follow-on work, will:

• Collect initial samples from the historical tailings storage facility.
• Assess the financial potential of tailings reprocessing to enhance project economics.
• Evaluate the opportunity to add to the operational life of the Winston Project.
• Quantify the potential for resource growth based on historical recovery rates.
• Support future environmental remediation by reducing the long-term footprint of legacy tailings.

Strategic Significance

Reprocessing the Winston tailings presents an opportunity to:

• Substantially increase the Winston Project's underlying value.
• Extend operational cash-flow and improve future returns.
• Advance environmental cleanup through the removal or treatment of legacy materials.
• Utilise existing site infrastructure to fast-track potential development.

Darren Hazelwood, Chief Executive Officer, commented:

"This tailings sampling programme is the first step in adding significant value to the Winston Project. Based on the historical mine processing recoveries, we believe there is a strong opportunity that the metal contained on the mine tailings could nearly double the known resource base at Winston - while also addressing legacy environmental impacts. This presents a rare opportunity to deliver both economic and environmental returns."

References

• Panther Metals PLC, announcement, Winston High-Grade Brownfield Critical Minerals Project: Panther Metals Secures Feasibility Study Stage Multi Element VMS Opportunity, dated 17 June 2025 (https://www.londonstockexchange.com/news-article/PALM/winston-high-grade-brownfield-critical-minerals/17088910 )

The Panther Metals Winston Project, located 50 km east of Thunder Bay, Ontario, Canada, is an advanced stage polymetallic zinc, copper and precious metal property comprising a high-grade critical mineral mine redevelopment and resource building opportunity. Based on a Feasibility Study published in 2021 the Project is expected to generate average life of mine ("LOM") annual EBITDA of C$67.64 million (M) and have a pre-tax NPV8% of C$ 175.8 M and IRR of 26%, with further strong exploration potential for defining additional Mineral Resources and Mineral Reserves from the two main deposits as well as additional near-mine volcanogenic massive sulphide ("VMS") exploration targets.

2021 Feasibility Study Headline Metrics

• NPV8%: C$175.8M pre-tax, assuming zinc priced at US$2,700/t, copper at US$7,300/t, gold at US$1,635/oz & silver at US$21/oz. At a derisked 6% discount Pre-tax NPV = C$213.2M.
• IRR: 26% pre-tax
• EBITDA : C$574.9M (gross), C$67.64M (annual). Gross revenue: C$983.3M
• CAPEX: C$145.1 M
• OPEX: C$65.17/t
• Indicated Resource 2.07 Million Tonnes @ 18% Zn
• Volcanogenic Massive Sulphide mineralisation well understood by Panther.
• Positive First Nation engagement.
• Strong Institutional and Governmental support for future financing options.

The 2021 Feasibility Study1 for the Winston Project detailed a strong economic case for mine redevelopment for a 1,000 tonnes per day underground operation with a net present value (NPV8%) of C$171.5M and pre-tax internal rate of return (IRR) of 26% based on an Ore Reserve of 1.96Mt @ 13.9% Zn, 0.6% Cu with significant gold and silver credits (Table 1) producing an expected 69.8 thousand tonnes per year (ktpa) of zinc concentrate and 5.3 ktpa of copper concentrate over an initial 8.5 year mine life. The Project boasts a high-grade CIM compliant Indicated Mineral Resource2 of 2.07Mt averaging 17.9% zinc, 0.8% copper, 0.4 g/t gold, and 34 g/t silver plus Inferred 0.27Mt @ 16.2% Zn, 1.0% Cu, 0.3g/t Au & 37.2g/t Ag (Table 2). Project is located only 20km from the trans-Canada highway and infrastructure including power, tailings storage facility, transport links and underground development are already in place. The previous mining operation closed in February 1999 due to very low zinc prices at the time. In total, 3.4 million tonnes grading 1.0% copper and 16% zinc was mined and processed. The total project area covers approximately 60.4km2 and comprises both patented freehold, leased and Crown-land mining claims.

Table 1: Winston Project Mineral Reserve

Notes: JORC (2012) compliant Mineral Reserve effective date 5 July 2019. Ore Reserves are based solely on Indicated Mineral Resources and are reported above an average net smelter return (NSR) cut-off grade of US$98 /t equivalent to 5.2% Zn. 1

Table 2: Winston Project Mineral Resource Estimate at 3% Zn cut-off grade

Technical References:

Commercial Strategy - Discovery-Driven Value Creation