Abstract

For more than a decade, new copper discoveries have been getting fewer, smaller and much deeper. The only major discovery in this period commences at 600m depth, and when
developed will become the world’s deepest copper mine.

Yet the world still offers abundant near-surface copper resources. Their ‘limitation’, being lowgrade, polymetallic and/or arsenic contaminated, is that they aren’t technically or economically suitable for beneficiation to smelter-grade concentrates. Closing the supply gap is substantiallya matter of developing solutions that operate beyond the technical limitations of smelters.

As the most common alternative to smelting, heap leaching can address only one of the problems (low grade), but it requires very long residence times, massive quantities of acid, and enormous land use – requiring extensive land remediation. It sacrifices substantial copper recoveries (typically at least 30%), and it fails to extract key co-occurring metals: gold, silver, lead, rare earths and more.

As a significantly better alternative, the Halion Loop™ applies and extends the well-known economic and environmental advantages of halide hydrometallurgy. Operating at atmospheric pressure and <100°C offers faster and cheaper extraction of copper and other metals from mineral ores, concentrates and tailings than any sulphate-based hydrometallurgy.

This paper will discuss key outcomes of studies on the use of the Halion Loop™ for the efficient extraction of target metals from a broad range of copper resources: low grade ‘preconcentrates’ (<8% Cu); high arsenic (>8%); large-grain (>1,000µm); polymetallic copperlead-zinc bulk concentrates; from refractory minerals, ores and tailings; and from waterconstrained and saline sites.

While these capabilities significantly extend the range of viable resources – even compared to previous halide hydrometallurgical processes – the key challenge that has hindered the commercial application of halide hydrometallurgy was the recovery of metal products, most particularly the recovery of copper as high purity metal.

The development of the Halion™ electrowinning cell is the critical step for ‘closing the loop’ on a cyclic process. It is the world’s first design for the practical, efficient production of
dendritic copper from halide electrolytes. Utilising the advantages of the cuprous copper state, this design significantly reduces the power consumption of copper electrowinning, as well as allowing for continuous production without the need to regularly handle and strip the cathodes.

The paper will also discuss the outcomes from the operation of Loop Hydrometallurgy’s pilot electrowinning cell during the first half of 2026.