Capstone Adds Cobalt Twist to Santo Domingo

Capstone Mining Corp. plans to vertically integrate cobalt production as it advances its Santo Domingo project in Chile toward construction by the end of the year. The company expects the production of battery-grade cobalt sulphate at Santo Domingo to add significant value to the copper-iron-gold project.

“Capstone has an incredible opportunity to produce ethically sourced battery- grade cobalt sulphate from Santo Domingo’s future copper-iron tailings stream,” President and CEO Darren Pylot said. “The process is a series of conventional steps, with below-zero costs given significant byproduct credits.”

By 2025, an estimated 140,000 metric tons (mt) of cobalt contained in cobalt sulphate will be required for lithium-ion (Li-ion) batteries. Capstone said Santo Domingo would be the only cobalt sulphate project in the Americas not dependent on third-party feed from the Democratic Republic of the Congo. Its cobalt processing capacity could supply enough battery-grade material for more than 500,000 electric vehicles (EVs) annually.

“A cobalt operation at Santo Domingo would unlock Chile’s vast potential for this critical metal and it is exciting that Capstone is leading this vision,” Pylot said. “The selection of a strategic partner due later this year will accelerate this unique project to recover a future-facing, green metal from a waste stream, a plan that I’m set on making a reality.”

Capstone’s concept for cobalt recovery is based on its bond with pyrite, which is concentrated by preferential flotation on a tailings stream. Approximately 840,000 mt per year (mt/y) of pyrite containing 0.6% cobalt and 0.4% copper is expected to be recovered at this step. The concentrate is fed through a five-stage process consisting of roasting, leaching, copper precipitation, cobalt solvent extraction and crystallization to yield battery-grade cobalt sulfate heptahydrate. Recovery of cobalt from pyrite concentrate is expected to be approximately 90% at very low cost due to significant byproducts from increased copper recovery, sulfuric acid production and energy generation, the company said.

The Santo Domingo concentrator is expected to commence construction in late 2021, with first year of operation in 2024. In related news, Capstone also announced it has entered into three separate agreements to advance the Santo Domingo project. It signed a $290 million gold stream agreement with Wheaton Precious Metals. The company will use $120 million to purchase Korea Resources Corp.’s 30% ownership interest in the Santo Domingo project consolidating its ownership position to 100%.

Capstone has entered into a framework agreement with Puerto Abierto SA, a subsidiary of Puerto Ventanas SA (PVSA), where PVSA assumes responsibility for the design build, operation and financing of the port, which reduces initial capital expenditure at Santo Domingo by an estimated $250 million, according to the company. Santo Domingo will guarantee a throughput commensurate with the economic recovery model for an agreed IRR and PVSA will have an option to purchase the facility outright subject to approval from environmental regulatory bodies.

As featured in Womp 2021 Vol 04 -