A global squeeze on sulphuric acid is exposing a less visible vulnerability in the critical minerals supply chain.
Rising costs and tightening physical availability are beginning to put pressure on the economics of copper, lithium, nickel, cobalt, and uranium projects.
Global law firm Squire Patton Boggs latest report, Mining and the global supply chain: The sulphuric acid crisis, states that China has permitted its first outbound shipment of sulphuric acid since May 2026, sending 32,000 tonnes from Nanjing to Chile, in a move that offers some relief to a market facing mounting supply constraints.
However, the shipment represents only a fraction of Chile’s annual sulphuric acid requirements, and it remains unclear whether further Chinese exports will follow.
That disruption matters far beyond the chemical sector.
Sulphuric acid is essential to mining because it is the primary chemical used in acid leaching to dissolve, separate, and recover valuable minerals and metals from low-grade or complex ores.
For mining companies, a shortage of the chemical can translate directly into higher processing costs, tighter margins, and, in some cases, reduced production.
The pressure has intensified following a series of export restrictions across major sulphur-producing and sulphuric acid markets.
Turkey imposed restrictions on sulphur exports in April, China introduced restrictions on most sulphuric acid exports in May, and Russia subsequently extended its own sulphur export ban, as reported by Squire.
The measures have added another layer of complexity to an already fragmented global commodities market, where miners are exposed not only to the availability of ore and concentrate, but also to the chemicals, energy, equipment, and infrastructure required to turn those resources into usable materials.
For developers and explorers, the disruption also highlights a broader issue: securing a mineral resource does not necessarily mean securing a viable supply chain.
Chile’s visible commercial impact
The commercial impact is already becoming visible in Chile, one of the world’s major copper producers and a key importer of sulphuric acid.
Squire reports that Chile’s CFR Mejillones spot prices doubled in under seven weeks, from US$190 ($268.18) per metric tonne on 25 February 2026, to US$380 per metric tonne by 15 April 2026.
Sulphuric acid’s share of hard-rock lithium processing costs has also reportedly increased from around 3% to 11%, while sulphur’s share of costs in certain nickel operations has risen from 26% to 42%.
For mining companies developing new projects, the implications extend beyond spot prices.
Squire says project developers must consider whether critical processing inputs will be available at scale, at what cost, and under what contractual terms once a mine enters production.
A project that appears economically robust based on mineral grades, recoveries, and commodity prices can face a very different equation when the cost or availability of a key consumable changes sharply.
That is what makes sulphuric acid more than a chemical supply issue. It is becoming another test of how resilient the global critical minerals supply chain really is.
As governments push to expand domestic mining, processing, and refining capacity for copper, lithium, nickel, cobalt, and uranium, the sector may need to look beyond the minerals themselves — and towards the less obvious inputs that make their production possible.
Projects and their exposure
For mining companies, the question is becoming less about whether sulphuric acid is available today and more about how exposed their projects could be if supply remains constrained.
That question is particularly relevant across the development pipeline, where companies are testing processing technologies that either depend on sulphuric acid or seek to minimise its use.
The pressure on sulphuric acid is relevant to emerging projects whose processing flowsheets depend on the chemical.
For example, Empire Metals (LSE:EEE) is developing its Pitfield Titanium Project in Western Australia around a hydrometallurgical route involving sulphuric acid leaching.
The company has been testing sulphuric acid leaching to extract titanium from Pitfield concentrates. This is achieved through an acid-bake and water-leach process designed to produce high-purity titanium dioxide from the ore.
Titanium dioxide pigments are produced using one of two methods: the sulphate process, which accounts for around 40% production and uses sulphuric acid, the chloride process, which accounts for around 60% and uses chlorine gas.
Empire Metals Managing Director Shaun Bunn says the company rejects 90% of the material mined during the flotation stage.
“That material hasn’t been chemically altered, so can go back into the mining void,” Bunn says.
The remaining 10%, which contains titanium, moves forward for acid digestion. At that stage, Bunn says, the company adds sulphuric acid to extract the titanium.
“We don’t need to smelt the material in a high-temperature sense,” he explains.
Empire Metals is currently focused on advancing Pitfield towards commercial operations, with mine planning, engineering, and economic studies expected to be carried out during H2 2026.
Detailed engineering studies based on the current flowsheet have already begun, while continuous pilot-scale test work will validate the process design criteria ahead of Feasibility Studies and produce bulk product samples. Product development work targeting coated rutile pigments and titanium sponge metal feedstock is also advancing.
In conjunction, Empire Metals is conducting work to support a further resource upgrade in mid-2027. The update will focus on converting material classified as indicated into the measured category.
Recently, Empire Metals also joined an Australian Government-backed research initiative to investigate titanium metal production from the project. The work will examine whether Pitfield’s titanium dioxide product can be converted directly into metal using molten salt electrolysis powered by renewable energy.
The research targets an alternative to the Kroll process, which remains the dominant method of titanium metal production.
Developed in the 1940s, Kroll involves converting TiO₂ into titanium tetrachloride before reducing it with magnesium. Its energy and labour requirements contribute to production costs that have largely confined titanium metal use to higher-value aerospace, defence, and medical applications.
Empire’s work to reduce acid consumption serves as a potential example of how miners and developers may need to optimise processing flowsheets as reagent costs and availability become increasingly important.
Not a confined issue
The issue extends into uranium, where sulphuric acid can form part of the recovery process.
Alligator Energy (ASX:AGE) is testing an acid-based in situ recovery process at its Samphire Uranium Project in South Australia, with recent field recovery trials recording sulphuric acid consumption of about 20 kilograms per tonne of ore.
The company uses mild sulphuric acid solution, known as lixiviant, as a key leaching reagent in its in situ recovery process.
In April 2026, uranium recoveries exceeded 55% after 39 pore volumes had been processed at Samphire.
As previously reported, pregnant lixiviant grades from the wellfield peaked above 200 milligrams per litre (Mg/L) triuranium octoxide (U₃O₈) and remained above 100Mg/L U₃O₈, based on on-site laboratory assays.
Managing Director and CEO Andrea Marsland-Smith says the results demonstrate the effectiveness of the process during field testing.
“Achieving greater than 55% recovery at this stage of the trial, with reagent consumption in line with expectations, demonstrates the effectiveness of the ISR process under field conditions,” CEO Andrea Marsland-Smith says.
For uranium developers, a sustained increase in acid prices could therefore become another consideration when assessing operating costs, reagent supply, and the scalability of future projects.
When processing pressure becomes contractual risk
The experiences of projects such as Pitfield and Samphire highlight why sulphuric acid supply is becoming increasingly important consideration for mining companies at the development stage.
For Empire Metals, reducing acid consumption has become part of the processing equation at Pitfield, while Alligator Energy’s Samphire Project is incorporating reagent management into its feasibility work.
But for companies already operating, developing, or contracted to supply projects, the issue extends beyond processing costs.
When a key reagent suddenly becomes more expensive or difficult to source, the question becomes who ultimately bears the additional cost, delay, and risk of non-performance.
That brings the sulphuric squeeze into the realm of commercial contracts, where force majeure, price adjustment, and hardship provisions could become important for miners, suppliers, refiners, and their counterparties.
The legal realm
According to Squire Patton Boggs, under English law, force majeure can only be relied upon where it is expressly provided for in a contract.
Depending on the wording, clauses covering government action, export bans, or embargoes could become relevant to the current restrictions on sulphur and sulphuric acid.
However, identifying an export restriction as a force majeure event does not automatically remove a company’s contractual exposure. Businesses must assess whether the event falls within the relevant clause, caused the disruption, meets the required threshold for relief, and could have been avoided or mitigated.
Invoking force majeure can provide short-term relief, but may also trigger termination rights, suspended supply commitments, or contingency obligations, creating longer-term commercial consequences.
Price adjustment, indexation, and hardship clauses may provide alternative avenues, allowing contracts to respond to significant price movements or changes that materially alter their economic balance.
For miners, the risk also extends beyond the immediate supply agreement. A company may obtain relief from a sulphuric acid supplier while remaining liable to offtakers, customers, lenders, or joint venture partners if production or delivery commitments are affected.
Companies facing disruption may therefore need to review their contractual risk allocation, notification requirements, and mitigation obligations, while assessing alternative suppliers and transport routes and documenting the financial and operational impact.
The sulphuric acid squeeze highlights a broader vulnerability in global mining supply chains: securing a mineral resource is only part of the challenge.
For explorers, developers, and producers, the availability and cost of the inputs needed to process those resources can be just as critical to project economics.
Write to Aaliyah Rogan at Mining.com.au
Main image: iStock
