What Does China's Acid Ban Mean for Chilean Copper Output?

Chile's mining sector is confronting a critical supply constraint as China prepares to halt sulphuric acid exports, a move that could curtail copper production at major operations across the country.

The anticipated restriction is exposing vulnerabilities in global mining supply chains and forcing operators to reassess sourcing strategies for a chemical integral to oxide copper processing.

As Chinese shipments taper off, Chilean mining operations face a dual challenge: securing alternative supplies whilst managing steep cost increases. A recent Reuters report captured the mounting anxiety among producers, with many now planning for scenarios where output could be constrained by input availability rather than ore grades or processing capacity.

Chile produces more copper than any other nation, with operations spanning from large-scale open-pit mines to underground deposits.

A significant portion of this output depends on leaching operations that require sulphuric acid to extract copper from oxide ores. The reliance on imported acid, particularly from China, has left the sector exposed to sudden disruptions in international trade flows.

Codelco faces mounting pressure

Codelco, one of the world's largest copper producers, sits at the epicentre of the supply challenge. The state-owned miner operates multiple sites that depend heavily on sulphuric acid for leaching operations, making it particularly vulnerable to both price increases and potential shortages.

BHP and Anglo American, both with substantial Chilean mining assets, are navigating similar exposure. Freeport-McMoRan, another major operator, could also feel pressure as the broader acid market tightens and costs rise.

The company's extensive leaching operations at sites including Chuquicamata and Radomiro Tomic require substantial volumes of sulphuric acid to maintain production targets. Any prolonged supply disruption could force operational adjustments that impact output forecasts and revenue projections.

Peter Harrisson, Principal Analyst at CRU, said on LinkedIn: "Acid traders are experts in problem solving but not all of this problem will be solved. The loss of Chinese trade cannot be replaced with other origins. Exports will be lower and imports will adjust to that. How and where are the real questions."

China withdraws from export markets

China is set to cease sulphuric acid exports from May 2026, removing flexible supply from global markets at a time when alternative sources remain constrained. The decision follows record export volumes in 2025 and represents a strategic shift towards prioritising domestic industrial demand.

Much of China's exportable acid originates as a by-product from copper and zinc smelting operations. This makes the export restriction particularly significant for mining operations elsewhere that have relied on competitively priced Chinese material to support their processing activities.

The timing compounds existing supply pressures. Conflict in Iran during March 2026 has disrupted sulphur shipments from the Middle East, a region that accounts for roughly one third of global output and a substantial portion of seaborne sulphur trade. As sulphur serves as the primary feedstock for sulphuric acid production, upstream disruptions have intensified downstream constraints for mining operations.

Approximately 60% of global sulphuric acid consumption supports fertiliser production, but the remainder underpins critical mining activities, oil refining and advanced manufacturing. The withdrawal of Chinese exports transforms what has historically been a low-profile industrial input into a strategic bottleneck with cross-sector implications.

Mining operations face broader constraints

Beyond copper leaching in Chile, nickel processing operations in Indonesia face similar pressures. Major nickel producers, including operations linked to Tsingshan, depend on stable sulphur inputs for their hydrometallurgical processes. Disruptions at this stage could ripple through battery supply chains, affecting electric vehicle production and energy storage manufacturing.

Silver production could also face indirect pressure. A substantial portion of global silver output comes as a by-product of copper mining operations. Constraints on copper production in Chile due to acid availability could therefore tighten silver supply at a time when demand remains robust.

Mining companies with oxide copper deposits are now evaluating alternative processing methods and accelerating plans to secure acid from regional producers or develop on-site production capacity. However, such adjustments require significant capital investment and time, leaving near-term output vulnerable to supply disruptions.

The broader implications extend to project economics across multiple jurisdictions, with cost pressures potentially affecting the viability of marginal operations and delaying expansion plans at existing sites where acid supply security cannot be guaranteed.

Sasa Jarvis, National Co-Leader of Mining and Partner at McMillan LLP, writes on LinkedIn: "If China is indeed curbing sulphuric acid exports, this could quietly reshape metals markets, particularly when sulphur from the Middle East is subject to severe shipping risks through the Strait of Hormuz.

"Acid leaching is required for much of global copper and nickel production - and impacts silver supply by extension given the amount of silver produced as a byproduct in copper mining. Copper and silver are each in short supply for current levels of demand already."