There's a substance that underpins copper cathodes, EV batteries, wheat fertilisers, and uranium extraction. It doesn't appear in earnings calls. It rarely features in commodity forecasts. Until a few weeks ago, most enterprise risk managers hadn't given it a second thought.
Sulphuric acid's moment has arrived — and it isn't a good one.
China has indicated it will halt exports of sulphuric acid from May, hitting metals and fertiliser industries already strained by raw material bottlenecks stemming from the Iran conflict. The ban covers acid produced as a byproduct of copper and zinc smelting — which is, quietly, how China became the world's dominant supplier. China's sulphuric acid production accounts for more than 40% of global output, making it the largest producer and exporter on Earth, with total capacity in 2025 reaching approximately 177 million tonnes.
That's not a swing producer. That's a structural anchor. And it's being pulled.
The numbers are already ugly. Sulphuric acid prices in Chile have risen 44% in a single month. Chile buys over one million tonnes of Chinese sulphuric acid every year, and roughly a fifth of the country's copper output — produced by the world's largest copper producer — depends on processing routes that require acid. Spot prices for sulphuric acid delivered to Mejillones, Chile, hit $300 per metric tonne on April 8th, up 57.9% from late February.
To understand why, you need to back up to the Strait of Hormuz.
The Iran conflict, which escalated in late February, effectively closed one of the world's most critical shipping chokepoints. The Middle East accounts for roughly one-third of global sulphur production and approximately 50% of seaborne sulphur trade — and sulphur is the primary feedstock from which sulphuric acid is made. Sulphur, in this region, is a byproduct of oil and gas refining, and the Gulf states have historically been among the world's most reliable exporters of it.
That supply corridor is now severely disrupted. Sulphur prices had already nearly tripled in the twelve months prior to the conflict — meaning the Iran war didn't create a fragile market, it further exposed one that was already stretched.
China's export halt compounds an already stressed situation into something potentially structural. Peter Harrisson, Principal Analyst at CRU, put it bluntly: "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."
That's a significant thing to say. In most commodity markets, supply gaps get arbitraged away. Traders reroute, producers pivot, prices signal the need for substitution. Harrisson's point — and it's worth sitting with — is that the supply gap here isn't a distribution problem. It's a production problem. You can't route acid from a country that doesn't have spare acid.
The mining companies most immediately in the crosshairs are the ones operating solvent extraction and electrowinning (SX-EW) facilities, a processing method that requires acid in bulk and accounts for roughly 20% of global copper supply. Ivanhoe Mines' executive co-chairman Robert Friedland warned that some copper producers are operating with less than 30 days of foreseeable sulphuric acid supply.
Not three months. Thirty days.
Among Chilean producers, exposure varies sharply. Codelco — the state-owned giant and the world's largest copper producer — has its own acid supply and sells within Chile. Antofagasta, by contrast, is described by analysts as the "shortest" in terms of acid coverage, meaning most exposed to spot market prices. BHP and Anglo American, both with significant Chilean assets, face similar pressure as input costs climb.
Doubling sulphuric acid prices would add at least 50 cents per pound to copper mining costs at SX-EW operations in Chile. At current elevated copper prices, that's manageable — barely. But it's a margin problem that gets worse the longer the ban holds and the longer Hormuz remains restricted.
The global dimension of this story gets less attention than Chile, but it's arguably more troubling.
Indonesia, which now accounts for more than 60% of global nickel production, imports around 75% of its sulphur from the Middle East — and has no domestic alternative. The country's High Pressure Acid Leach (HPAL) nickel operations, dominated by players including Tsingshan and backed by Chinese capital, feed battery-grade nickel to manufacturers like CATL. Disruptions at this stage ripple directly into EV production timelines and battery storage costs globally.
Kazakhstan, the world's largest uranium producer at 39% of global supply, is also exposed. Kazatomprom consumed 1.85 million tonnes of sulphuric acid in 2025 for its in-situ leach uranium mining operations, and had already warned of production limitations due to acid shortages before the current crisis. The company is constructing a dedicated 800,000-tonne acid plant — a response that tells you everything about how seriously it views the underlying dependency.
Then there's food. Roughly two-thirds of sulphuric acid production feeds fertiliser output, especially phosphate fertilisers critical to crop yields. China had already restricted phosphate fertiliser exports through 2026 and is now tightening exports of the acid needed to make them, compounding the squeeze on global nutrient supply. For import-dependent regions in South Asia and sub-Saharan Africa, where fertiliser cost increases flow directly into crop yields and food prices, this is a food security question, not just a mining one.
"These events shift the burden from Chinese smelters to copper mines in Chile, mining operations in Congo, and fertiliser blenders in India. The Iran conflict created a shortage of raw materials. China's export halt triggers a commercial drought." — Syed Salman Shaffi, President, Gold Miners Club
Here's the contrarian read, though, and it's worth raising: China may not hold this ban as long as markets fear.
Bloomberg has reported that China has sent signals it is considering resuming sulphuric acid exports — specifically the byproduct acid from copper smelting — that it had suspended from May. Market participants have noted the ban was primarily a response to sulphur scarcity caused by the Iran conflict, and a Japanese investor at the CESCO Week copper conference noted that the Chinese planting season — the key domestic demand driver — is almost over.
In other words: if Beijing's primary motivation was protecting domestic fertiliser supply during spring planting, the urgency dissipates as summer approaches. The ban might be a seasonal valve, not a strategic pivot. Codelco reportedly moved early, locking in sulphuric acid supply before the recent price spike — and Ivanhoe has positioned itself as a seller of smelter byproduct acid into an acid-starved DRC market. Companies that hedged smartly are watching competitors scramble.
The less reassuring version of this story is structural: the Hormuz shipping chokepoint isn't going to reopen on a seasonal schedule, and the sulphur market was already tightening before the first shot was fired. A temporary Chinese reprieve doesn't fix a global feedstock shortage. It just removes one pressure while others remain.
The downstream implications for tech hardware, EVs, and data infrastructure deserve attention. Copper is everywhere in the physical internet: undersea cables, data centre busbars, EV charging networks. A sustained reduction in Chilean SX-EW output — a long-lasting ban could impact copper cathode production in Chile, according to S&P Global Energy CERA analyst Yuya Pan — tightens a market that was already running structural deficits. Silver, often ignored, faces a parallel squeeze: roughly 72% of global silver is a byproduct of base metal mining, with copper alone accounting for about 27%, and the silver market has been in structural deficit for five consecutive years, with cumulative shortfalls exceeding 800 million ounces since 2021.
The phrase "critical minerals" gets applied mostly to lithium and cobalt. The sulphuric acid story is a reminder that the enabling chemistry for those minerals — the leaching agents, the processing inputs, the feedstocks — carry their own geopolitical exposure. They just don't get conference panels.
What enterprise decision-makers should be tracking in the weeks ahead:
Whether China issues a formal timeline or guidance on resuming sulphuric acid exports; any signal from the NDRC will move Chilean spot acid prices immediately and could provide relief to mid-tier miners operating close to margin
The trajectory of Strait of Hormuz shipping volumes and whether sulphur tanker routes show evidence of rerouting via the Cape of Good Hope — a longer, more expensive path, but viable — which would signal the market is beginning to self-correct
Antofagasta's quarterly disclosures, which will be the most transparent early indicator of how much acid exposure is actually translating into production cost or volume impacts at a major listed miner
The practical question for procurement and supply chain teams isn't whether to hedge copper price exposure — most already do. It's whether they've stress-tested their inputs for the chemicals that sit one level below the metals they track. Sulphuric acid didn't feature on most risk registers six months ago.
It does now.
