Highland Copper is progressing with detailed engineering and optimisation studies at its Copperwood project in Michigan, US, with the aim of publishing an updated feasibility study in the first quarter of 2027 (Q1 2027).
The ongoing work will support both project development and finance planning.
As part of its review, the company is evaluating whether to lower the cut-off grades used to define mineable resources, based on a long-term copper price of approximately $4.8/lb.
This could enable additional measured and indicated mineral resources to be included in the mine plan.
Highland Copper is also examining the potential application of bulk ore sorting technologies.
If viable, these options could allow the upper copper bearing sequence (UCBS) to be added to future mine plans. The UCBS contains 10.2 million tonnes (mt) at 1.1% copper in the measured and indicated category but is currently excluded from reserves.
The resource estimate currently includes 54.2mt in the measured and indicated category at a grade of 1.51% copper.
Geotechnical investigations are being used to refine mine design, including mining heights, pillar dimensions and dilution sources.
Current work suggests that dilution could be sourced from the mineralised hanging wall rather than the floor.
Metallurgical test work completed last September evaluated an alternative mill-float-mill-float processing flowsheet and showed projected improvements in copper recovery.
The company projects average life-of-mine copper recovery of around 87.6%, up from 86% in the 2023 feasibility study, while anticipating lower secondary milling requirements and reduced energy and reagent use.
However, Highland Copper notes that these projections are based on test work and engineering assumptions and may differ under operational conditions.
Highland Copper CEO Barry O’Shea said: “As we continue our integrated mine plan review against a backdrop of significantly improved long-term consensus copper prices, we are encouraged by the opportunities to further optimise Copperwood through mine design, processing and engineering enhancements.
“These initiatives have the potential to strengthen project economics and will be incorporated into the updated feasibility study.
“With Copperwood advancing towards a construction decision, the project is entering an increasingly important stage of development at a time when few new copper projects are positioned to come online in the US in the near term.”
Test work conducted at Responsible Mining Solutions in Sudbury, Ontario, Canada, has shown that thickened tailings with around 55% solids by mass can be produced for the Copperwood project.
Highland Copper is considering this approach in its tailings deposition facility design, which may decrease the facility’s size and lower initial construction costs.
Thickened tailings could also improve process water recovery and lower pumping expenses.
Completion of 40% of the front-end engineering and design is targeted by the end of 2026, in preparation for technical due diligence for future project financing.
