Chinese exports of sulfuric acid to Chile — the world's largest copper producer — dwindled to zero in March 2026, the first total halt since July 2023, according to Chinese customs data. (FACT: Reuters, April 22, 2026) In March 2025, China had exported 151,268 tonnes to Chile; in February 2026, the figure was 31,870 tonnes. The last shipment was zero in March, and Beijing's subsequent announcement of a May-through-December export ban on sulfuric acid has removed all prospect of near-term recovery.
The disruption is the consequence of two unrelated supply shocks converging on a single point. First, China's export ban — motivated by the need to protect domestic smelter feed economics and ensure adequate acid for its fertilizer industry — removes approximately 3 million tonnes from the global seaborne market annually. (FACT: European Business Magazine, May 12, 2026) Second, the closure of the Strait of Hormuz due to the Iran conflict has blocked Persian Gulf sulfur shipments, the primary raw material for sulfuric acid production, while Russia has extended its own sulfur export ban through June 2026. The two shocks are uncorrelated and cannot self-correct simultaneously. (FACT: Discovery Alert, May 5, 2026)
Chile is uniquely exposed. The country produces over 5.5 million tonnes of contained copper annually, but roughly half of its refined output (approximately 2 million tonnes) comes from leaching — a process that consumes large volumes of sulfuric acid. Chile depends on imports for 37% of its acid supply, the majority of which came from China. (FACT: HSBC via Reuters, April 22, 2026) Spot sulfuric acid prices have approximately doubled from pre-disruption levels. (FACT: Discovery Alert, May 5, 2026) Morgan Stanley estimates that 1.1 million tonnes of Chile's annual leached copper production could be at risk from the acid export ban. (FACT: Morgan Stanley via Reuters, April 22, 2026)
The mechanism is non-linear. Sulfuric acid is non-substitutable for solvent-extraction-electrowinning (SX-EW) operations, which produce roughly 15-20% of global refined copper. (FACT: European Business Magazine, May 12, 2026) Unlike ore, acid cannot be stockpiled indefinitely and its supply is governed not by copper demand but by smelting, sulfur combustion, and oil refining — industries with entirely different economic cycles. Wood Mackenzie's April 30 outlook identified sulfuric acid availability, treatment charge compression, trade policy, and fiscal risk as the operative supply constraints on copper, "explicitly noting that none of these constraints reside in a resource statement." (FACT: Discovery Alert, May 5, 2026)
Domestic Chilean acid supply from Codelco, Noracid, and Anglo American covers near-term needs but loses visibility beyond mid-2026. (FACT: European Business Magazine, May 12, 2026) Chinese acid shipments that once went to Chile have been redirected to the Philippines, India, and Indonesia — all of which received sharply higher volumes in March. Meanwhile, the relationship between Chilean miners and Chinese smelters has deteriorated as tight ore supplies have shifted treatment charges heavily in favor of mining operators, reducing Chinese smelters' incentive to ship acid back. (FACT: Reuters, April 22, 2026)
The timeline for resolution is measured in years, not months. Freeport-McMoRan aims to reach 65% capacity at its own sulfuric acid production by H2 2026 and near full capacity by end-2027. (FACT: Mining.com, May 4, 2026) In the DRC, Kamoa-Kakula's smelter produces approximately 117,871 tonnes of acid annually — valuable but insufficient to fill Chile's gap. The fundamental reality is that copper supply is now constrained by a chemical reagent, not ore grades or mining capacity.
The number that matters for your business
If Morgan Stanley's 1.1Mt-at-risk scenario materializes partially — say a 500,000-tonne reduction in Chilean leached output — the impact on the global copper balance exceeds the entire ICSG's projected 2026 surplus of 96,000 tonnes by a factor of five. A buyer contracting 10,000 tonnes/year of copper cathode would face not just higher prices (the LME is already at $13,600+/t) but physical availability risk — the acid bottleneck creates a supply shock that cannot be resolved by higher prices alone, because acid does not respond to price signals from the copper market.
Action: For buyers sourcing copper cathode from SX-EW operations (primarily Chilean), request acid supply assurance clauses in Q3-Q4 2026 contracts. Refined copper from smelters (those producing acid as a byproduct) is more secure than leached copper. Diversify quarterly allocations toward smelter-based supply where possible. For term contract buyers, the acid disruption is a valid force majeure trigger — clarify counterparties' vulnerability to Chinese acid supply.
Horizon: The acid shortage is structural through at least H1 2027. Resolution requires either the Strait of Hormuz reopening, China lifting its export ban, or new domestic acid production in Chile — none imminent. Treat the supply risk as active for all Q3 2026-Q4 2027 procurement.
Trigger: Watch (1) monthly Chinese customs data for acid exports — zero to Chile is now the baseline; any resumption is a positive signal; (2) Chile's domestic sulfuric acid production data published by Cochilco — if domestic output does not rise to offset the gap by Q4 2026, leached output reductions become inevitable; (3) spot acid prices in Chile — a sustained doubling from pre-disruption levels signals the physical shortage has crossed into production impact.