For three years, Beijing progressively tightened access to the minerals Western supply chains depend on. In May 2026, it moved to the industrial chemicals needed to process them - a shift that sits within a broadening export control architecture now spanning the full breadth of the critical minerals value chain.
While the world spent the last three years tracking China's restrictions on gallium, germanium, graphite, antimony, and rare earths, a separate category of exposure was building quietly in the background.
Industrial chemicals - the reagents underpinning the extraction of those same materials - attracted comparatively little scrutiny from policymakers or financial analysts during that period, and the gap has now translated into measurable production costs for miners and processors supplying the energy transition.
On 1 May this year, China formally suspended exports of industrial sulphuric acid, the chemical workhorse underpinning heap-leach copper extraction, HPAL nickel refining, uranium leaching, and the global phosphate fertiliser chain.
Rather than a formal government announcement, the restriction was communicated through producer notifications and trade channel communications to international buyers, covering byproduct acid from copper and zinc smelting.
The timing compounded the damage considerably.
When hostilities commenced at the end of February 2026, tanker transit volumes through the Strait of Hormuz fell approximately 90% - not the result of a formal closure order, but the practical consequence of war risk insurance premiums making shipments commercially unviable and shipowners unwilling to risk vessels and crew in an active conflict zone.
Sulphur, the primary feedstock for sulphuric acid production, flows heavily through the Strait, and Chinese domestic sulphur prices rose 170% year-on-year by early April 2026 as supply chains adjusted to the disruption - before China's own export restriction layered further pressure onto a market with few quick substitution options.
On the rationale, Lynn Song, chief economist for Greater China at ING, addressed the question directly in the Southern China Post, noting he had not seen official notifications from government agencies.
"Administrative controls are expected to amount to a de facto suspension of sulphuric acid exports from May 2026," Song said.
"I'd imagine the intention would be to secure fertiliser supply, which is currently at risk thanks to the blockage of the Strait of Hormuz, which accounts for around a third of seaborne fertiliser trade as well as a lot of global sulphur exports."
Song added that the contribution of sulphuric acid exports to gross domestic product was far less important to Beijing than the broader goal of safeguarding domestic food security.
What the data also showed was that the restriction had not arrived without warning for anyone watching the numbers.
Chinese sulphuric acid exports were already down 50% across the first two months of 2026, as the NDRC progressively tightened its export quota from 1.3 million tonnes for January-April 2025 to 700,000 tonnes for the equivalent period in 2026 - with a substantial volume removed from the market before the formal ban was flagged.
Three years, 14 measures, now the acid
Understanding where the sulphuric acid ban sits requires reading it against the full three-year sequence rather than as a standalone event.
Global Trade Alert's tracking of China's export control regime documents a steady escalating sequence: gallium and germanium in July 2023, graphite in October, antimony and superhard materials in August 2024, tungsten and tellurium in February 2025, and certain medium-to-heavy rare earth elements by April 2025.
With each round, scope widened - moving from select strategic metals to cover different value-chain stages, related intermediate products, and following the October 2025 measures, the underlying technologies used to process controlled materials in facilities outside China.
Jack Lifton, co-chair of the Critical Minerals Institute, identified the chemical layer as the operative exposure point in an April 2026 briefing that preceded the formal ban by weeks.
"The bottleneck isn't ore - it's chemicals," Lifton said.
"And China controls them."
Lifton described sulphuric acid as "one of the key reagents in all processing of metals, minerals, and the manufacturing of chemicals", and stated that China restricting exports "is going to have tremendous impact on the non-Chinese chemical industry and metal processing industry".
Within that sequence, research from the Swedish National China Centre identifies two distinct phases.
First wave controls on gallium, germanium, graphite, and antimony arose primarily from U.S. technology restrictions on semiconductors and advanced computing; second wave restrictions in 2025, targeting rare earth elements, were deployed as a tool in the broader U.S.-China trade and tariff conflict that developed through that year.
Price history
Price data across affected materials documents how comprehensively each control round moved markets.
Gallium export volumes averaged 66% below pre-control levels following the July 2023 restriction, with European spot prices rising 365% across the same interval; wrought germanium exports fell 60% with prices up 400%; and antimony exports were effectively zero for extended periods, accompanied by a 437% price increase that disrupted defence procurement and munitions supply chains across the NATO alliance.
Beyond the headline bans, the licensing mechanism has functioned as a parallel instrument within the regime.
The nominal 45-day review window has stretched considerably longer in practice, producing delivery disruptions, delayed payments, and downstream production stoppages without a formal prohibition needing to be declared in each case.
Following U.S.-China trade talks in May 2025, Beijing suspended dual-use export control listings for several American firms as part of broader bilateral negotiations - the same mechanism that had been used as a trade restriction functioning as a diplomatic concession depending on where negotiations stood.
Chile: first cab off the rank for pain
Sulphuric acid is not a strategic metal embedded in a finished product, but the industrial input required to unlock the ore bodies producing those metals.
Chile's position as the world's largest copper producer, combined with its deep reliance on Chinese acid imports, made the country particularly vulnerable when both supply sources came under pressure within weeks of each other.
Chinese shipments to Chile had already collapsed to zero by March 2026, down from 151,268t in the same month the prior year, as the quota tightening through Q1 progressively exhausted available supply before the formal ban took effect.
Benchmark prices at CFR Mejillones climbed from US$190 per metric tonne on 25 February to $300/t on 8 April, reaching $380/t by 15 April - a doubling in under seven weeks as the Hormuz sulphur shortage and the incoming Chinese ban pressed the market hard from either side.
Around 20% of Chile's national copper output depends on heap-leach oxide processing, which requires a reliable acid supply regardless of ore grade or capital investment - making the exposure structural rather than operational.
Unlike sulphide flotation, heap-leach oxide processing has no workaround when the reagent runs short, which is why Chile imports over one million tonnes of Chinese sulphuric acid annually to keep those operations viable.
Peter Harrisson, principal analyst at CRU, was direct on the substitution question in comments published by Mining Digital in April.
"Acid traders are experts in problem solving but not all of this problem will be solved," Harrisson said.
"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."
An assessment of uncovered H2 2026 demand by S&P Global Platts commodity specialists reached a similar conclusion - Peru is the most proximate alternative source, available capacity there is limited, and logistics constraints rule out timely substitution from more distant producers.
For BHP, Anglo American, and Freeport-McMoRan, outcomes through H2 hinge closely on the contract cover positions each held entering the disruption.
Indonesia, the DRC, and an overcooked battery chain
Chile's predicament is acute, but Indonesia's HPAL sector is navigating a version of the same problem with less margin to absorb it.
Significant nickel processing capacity has been built across Indonesia on the assumption that acid supply from both the Middle East and China would remain accessible through the decade - an assumption the current disruption has put under severe strain.
Between July 2024 and January 2026, the sulphur price to Indonesia rose 440% - from $101 per metric tonne to $554/t - driven by HPAL capacity additions pushing domestic demand upward before the Iran conflict added further cost pressure to an already tightening market, according to Atlantic Council analysis.
With 75-80% of sulphur supply sourced from the Middle East and approximately 60% of acid imports sourced from China, Indonesian HPAL operators are exposed on both reagent input lines at the worst possible time in their capacity build-out.
"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," McMIlan partner Sasa Jarvis said.
"Copper and silver are each in short supply for current levels of demand already."
S&P Global CERA analysts flagged a pronounced risk of output curtailment, particularly for battery-grade mixed hydroxide precipitate, as reagent cost inflation weighs on operations already running on narrow returns in an oversupplied nickel market.
In the DRC and Zambia, the numbers are harder still.
Acid imports account for 85-90% of total supply in both countries, with landed costs having surpassed US$1,000t in April - compressing margins on copper and cobalt operations already navigating conflict-related logistical constraints through Q1.
Beyond acid - the broader architecture
Whether the sulphuric acid ban belongs in the same policy category as gallium and rare earth controls - or reflects a domestic supply management response to the Hormuz disruption - remains unconfirmed, with no official Chinese government statement issued on the rationale, duration, or conditions for reversal.
What the three-year record does show is a regulatory framework building legal foundations since the 2020 Export Control Law that has extended coverage progressively across minerals, reagents, processing technologies, and extraction-related intellectual property - a breadth that is not visible when individual measures are read as discrete policy events rather than as a sequence.
Lifton extended his assessment to rare earth extraction specifically, noting that the chemical inputs for ionic clay processing - ammonium sulphate and magnesium sulphate - are produced overwhelmingly inside China.
"The clays are washed with chemicals, either ammonium sulphate or magnesium sulphate," Lifton said.
"The overwhelming amount of those two chemicals manufactured in this world is manufactured in the People's Republic of China - and they will no longer export either if your use is extracting rare earths from ionic clays."
The October 2025 measures extended licensing requirements to products manufactured outside China using Chinese-origin technologies - covering rare earth mining, refining, smelting, magnet production, and recycling - making them subject to controls even where they contain no physical Chinese materials.
Under extraterritorial provisions effective from November 2026, international firms are now required to monitor, document, and report the presence of Chinese-origin controlled content across their product lines.
Across the Western critical minerals sector, the exposure now covers the minerals themselves, the reagents used to process them, and the technologies governing that processing - three layers of dependency whose combined weight only becomes visible when the individual measures of the past three years are read as a whole.
What to watch
- H2 2026 Chilean copper output - whether uncovered sulphuric acid demand translates into cathode curtailments or is absorbed through inventory draws; the volume impact is expected to clarify through Q2 earnings reporting from major producers from July onwards
- Indonesian HPAL operating rates - reagent cost inflation pressing on already-thin nickel margins could produce output cuts that tighten battery-grade supply ahead of the timeline the current oversupply consensus implies
- Official Chinese government confirmation - no formal policy statement has been issued on rationale, duration, or reversal conditions; confirmation would sharpen the analytical read across commodity and policy research communities
- U.S.-China bilateral trade track - quota-based relief following diplomatic engagement, consistent with the pattern established with gallium licences in late 2025, remains a plausible near-term outcome if negotiations advance
- Sulphur price trajectory - resolution of the Hormuz conflict would ease the feedstock shortage, reduce the domestic rationale for maintaining the acid export restriction, and potentially prompt an administrative quota adjustment ahead of any formal announcement
