South32 has secured board approval to spend $2.16bn (A$3.32bn) to develop the zinc-lead-silver deposit at the Hermosa project, located in a mining district in the Patagonia Mountains of southern Arizona, US.

The Hermosa project is distinguished as the only advanced US mining project that can produce two federally designated critical minerals, zinc and manganese, which are pivotal for the clean energy sector.

The project, which is recognised as the first critical minerals mining project under the US' FAST-41 permitting process, is poised to become one of the largest zinc producers globally.

Covering an area of more than 600 acres, the project is said to integrate sustainability and the latest technology in its underground mine design, incorporating automation to enhance efficiency and reduce greenhouse gas emissions.

The investment from South32 will finance the construction of critical infrastructure including water management systems, power, site facilities and underground development.

This infrastructure will also support the future development of other deposits such as battery-grade manganese.

According to the feasibility study, the Hermosa mine is expected to have an initial lifespan of around 28 years, with prospects for more exploration.

The operation is expected to generate up to 900 jobs and contribute to Arizona's economy, potentially adding $1.4bn annually, with $999m benefitting Santa Cruz County directly.

Hermosa project president Pat Risner said: “With the largest private investment in southern Arizona’s history, South32’s Hermosa project will strengthen the domestic supply of critical minerals needed for clean energy technologies and national defence, reducing America’s reliance on foreign countries and transforming the local economy.”

Recently, Stanmore Resources agreed to acquire South32’s 50% interest in the Eagle Downs Metallurgical Coal joint venture project in Queensland, Australia.