Toronto- and Sydney-listed Marimaca Copper has signed a binding option to acquire a sulphuric acid plant in Chile in a move that should reduce one of the biggest input costs for its planned oxide copper mine.

The Vancouver-based miner agreed to pay $2.5-million for the plant, previously operated by CEMIN Holding Minero. The asset, capable of producing as much as 150 000 t/y of sulphuric acid, could cover 30% to 40% of consumption at the Marimaca oxide deposit, depending on the stage of development.

“The Marmica oxide deposit is forecast to be a mid-level acid consumer in the context of Chilean heap leach operations, and we continue to recognize acid cost as one of our most important drivers of profitability,” CEO Hayden Locke said in a statement. “Lowering the volatility associated with one of our key consumables was a logical step for the company.”

The deal comes with a three-month exclusivity period to complete engineering and technical reviews. Marimaca has already conducted due diligence including site visits and third-party engineering reports.

Sulphuric acid prices in Chile have been volatile owing to high shipping costs and global fertiliser demand. Locke said that projections from the State copper commission Cochilco suggested long-term prices would normalise at about $95/t in Mejillones from 2028. “Our analysis indicates, based on today’s elemental sulphur price, a company-owned acid plant could produce sulphuric acid for approximately $70/t, excluding by-product credits from heat generation,” he said. “This represents an approximate 30% reduction from the current long-term acid price forecasts from Cochilco.”

Marimaca will make an upfront payment of $1-million followed by $1.5-million after the due diligence period, with relocation and startup costs expected to be significantly lower than a new build. A comparable new plant could cost as much as $60-million, according to the company.

The company said its definitive feasibility study for the Marimaca oxide deposit, now in final review, would not capture the upside from the potential acid strategy, but that the move represented a “clear opportunity for optimisation".