With global sulphuric acid markets in crisis following the Strait of Hormuz closure, China's export ban, and Zambia's supply restrictions, an unexpected source of relief has emerged in the Democratic Republic of Congo. Kamoa-Kakula's newly commissioned copper smelter produced nearly 118,000 tonnes of high-strength sulphuric acid in its first full operating quarter alone, reshuffling regional supply relationships and turning traditional competitors into customers. But analysts warn that byproduct acid is a buffer, not a solution, and the industry must start treating reagent availability as a hard production constraint.
Introduction
If you want to understand why a newly commissioned copper smelter in the Democratic Republic of Congo has become one of the most strategically significant facilities in global mining right now, start with a simple fact about chemistry. Processing copper oxide ore through solvent extraction and electrowinning, the method used to produce roughly 15% of global copper cathode, requires large and continuous volumes of sulphuric acid. No acid, no copper. It is that direct.
As I reported in August, sulphuric acid has quietly become one of the most exposed chokepoints in the entire critical minerals supply chain. The convergence of the Strait of Hormuz closure in February 2026, China's full export ban announced in April, and Zambia's earlier export restrictions created a supply shock without recent precedent. Copperbelt miners found themselves rationing chemical stocks, cutting throughput, and watching spot prices in Kolwezi spike as high as $700 per tonne earlier this year.
Into this gap has stepped an unlikely source of relief: the byproduct stream from smelting copper sulphide concentrates. When sulphur-bearing concentrates are roasted, they release sulphur dioxide, which can be captured and converted into sulphuric acid through a well-established industrial process. For the Kamoa-Kakula copper complex, which commissioned Africa's largest copper smelter at the very end of 2025, this byproduct stream has rapidly become a regional supply anchor, and a commercially significant one at that.
This article looks at what Kamoa-Kakula's acid production actually means for the Copperbelt in scale terms, why it is reshaping commercial relationships between companies that would not normally be customers of each other, and what the episode reveals about a structural blind spot in how the mining industry thinks about reagent risk.
What the Numbers Actually Say
Kamoa-Kakula's smelter achieved first copper anode production on December 29, 2025, roughly five weeks after the heat-up process began. By the time the Q1 2026 production figures were published in April, the facility had already generated 117,871 tonnes of high-strength, 98%-pure sulphuric acid in its first full operating quarter. Of that, 107,700 tonnes were sold to six offtakers at an average realised price of $467 per tonne. The remainder went into on-site inventory.
To put that figure in context: the smelter was running at an average of around 1,350 tonnes of acid per day in Q1, equivalent to roughly 480,000 tonnes annualised. That is well below its steady-state design capacity of 700,000 tonnes per year, because concentrate feed is currently constraining the ramp-up beyond about 60% of copper production capacity. Full smelter throughput is not expected until 2028. Even so, the facility is already producing acid at a rate that exceeds what many mid-sized national markets consume in a year.
Q2 2026 showed a slight dip in daily production rate, to approximately 1,250 tonnes per day, but sales volumes actually increased: 119,603 tonnes were sold during the quarter at an average price of $465 per tonne. That average price flatters the picture somewhat, because many of those contracts were signed before the most acute phase of the price spike. By May, a new offtake contract was signed for delivery the following month at $725 per tonne. Contracts for July and August were priced at approximately $840 per tonne, a level Ivanhoe described as a record for its acid sales.
The DRC alone represents an annual acid market of roughly two million metric tonnes. Even at Kamoa-Kakula's projected full-capacity output of 600,000 to 700,000 tonnes per year, domestic smelter byproduct covers only around one-third of regional leaching requirements. That gap matters, and it shapes everything about how this supply story should be read.
Competitors Become Customers
One of the more striking aspects of the Kamoa-Kakula acid story is who is buying. Speaking on the sidelines of CESCO Week in Santiago in April, Ivanhoe CEO Marna Cloete told Reuters that the acid was going to, among others, Glencore and Eurasian Resources Group. Both are major operators in the DRC Copperbelt and, in copper production terms, direct competitors of Ivanhoe. The supply shock has pushed them into the role of customers.
"We've got a captive audience in terms of our distribution," Cloete said, noting that restrictions on Zambian sulphur exports had prevented DRC operators from producing their own acid. The characterisation is accurate in a narrow commercial sense: with Chinese volumes gone, Zambian exports restricted, and Middle Eastern sulphur stranded, buyers inside the DRC have very limited alternatives at the volumes and timescales they need.
Ivanhoe's founder and executive co-chairman Robert Friedland was equally direct about the structural advantage this creates for the company. Kamoa-Kakula, he noted, does not require sulphuric acid for its own production process. Smelting copper sulphide concentrate to produce 99.7%-pure copper anodes generates acid as a byproduct rather than consuming it as an input. "Against this backdrop, Kamoa-Kakula is ideally positioned as a producer and seller, and therefore not a consumer, of sulphuric acid," he said.
The financial mechanics reinforce the point. In Q1 2026, the smelter's operating costs averaged $0.27 per pound of copper produced. Sulphuric acid byproduct credits came in at $0.32 per pound, meaning the acid revenue more than covered the smelter's own operating cost. Kamoa-Kakula's all-in cash cost fell to $2.58 per pound in the quarter, below the lower end of Ivanhoe's own guidance range of $2.60 to $3.00 per pound. The acid stream has moved from a line item to a margin driver.
The six offtakers currently purchasing at the mine gate represent a deliberately local distribution model. S&P Global CERA analyst Patricia Barreto captured why this matters: "Transport costs and safety constraints make this a regional market, so replacing Chinese volumes is not just a pricing issue but a physical availability one." Inland DRC does not have the road, rail, or port infrastructure to receive replacement acid volumes from Chile, East Asia, or the Middle East at commercial scale on short notice. The logistics dependency is nearly as binding as the economic one.
A Partial Fix in a Very Large Gap
It is important not to overstate what byproduct acid from Kamoa-Kakula, or from any single facility, can accomplish against the scale of the current shortage. The DRC's annual acid demand sits at roughly two million tonnes. Domestic acid production from concentrate plants had already plateaued at around 550,000 tonnes since 2022, even as SX-EW output continued to grow. That structural gap was widening before the 2026 shocks arrived.
The Strait of Hormuz disruption removed the supply source for approximately 80% of sulphur imported into Africa, according to Ivanhoe's own assessment. Monthly sulphur shipments through the strait fell from an average of 1.27 million tonnes before the conflict to just 30,000 tonnes in April 2026, according to Kpler data. China's export ban, which replaced an annual quota of 700,000 tonnes with a complete cessation from May 2026, removed the secondary backstop at precisely the moment the primary supply route was also failing. Zambia's September 2025 export ban, subsequently partially relaxed in May 2026 with limited permitted volumes, closed the regional alternative.
The result has been severe for non-integrated operators. Some DRC copper producers have seen operating costs surge by approximately $3,000 per tonne compared to 2024 levels, driven primarily by acid costs and energy. Standalone SX-EW plants without their own acid supply or renewable power have been pushed toward zero or negative margins. Miners have been reducing chemical consumption to extend stockpiles, a practice that directly reduces copper output volumes. Goldman Sachs projected potential copper production losses of approximately 125,000 tonnes if disruptions extended into mid-2026.
Kamoa-Kakula's Q1 production of around 118,000 tonnes of acid is genuinely useful, but it functions as a regional buffer rather than a structural solution. It absorbs some of the demand that would otherwise go unmet. It does not, on its own, close a gap measured in millions of tonnes.
The Integrated Versus Non-Integrated Divide
The Kamoa-Kakula episode has sharpened a distinction that the mining industry has historically underweighted: the difference between integrated and non-integrated copper producers when acid markets tighten.
Integrated operators, those that smelt their own sulphide concentrates and capture the resulting acid stream, are insulated from the procurement market in ways that non-integrated operators are not. Codelco in Chile is the most often cited example in the global context: it generates significant acid from its smelting operations and is partially sheltered from seaborne market movements. BHP Escondida and Antofagasta, by contrast, depend on purchased acid and are fully exposed to the current squeeze. In Chile, spot acid prices rose 100% between late February and mid-April 2026, with a further 26.7% increase in a single week in mid-April alone.
In the DRC, the divide is playing out at an operational level that has now become visible in quarterly financial results. Companies with on-site smelting capacity and acid capture are in a structurally different position from those running SX-EW operations that must buy acid from the market. At current spot prices approaching and exceeding $840 per tonne for forward contracts, this difference is not marginal. It is, for some operators, the difference between a viable and an unviable operation.
The Indonesia parallel is instructive. Indonesia's high-pressure acid leach (HPAL) facilities for nickel processing import roughly 75 to 80% of their sulphur from the Middle East. With that route disrupted, Indonesian operators have been competing for smelter byproduct acid from Japan and Korea, the same supply stream that Chilean copper producers are seeking. Different sectors, different geographies, same acid. Huayou has already cut output at one Indonesian facility by approximately 50%. The competition for smelter byproduct acid is now a genuinely global phenomenon.
The IEA's July 2026 copper supply warning made the systemic risk explicit: "Constraints on sulphuric acid availability pose a significant risk to SxEW production." That is a notable statement from an institution whose analysis has historically focused on ore grades, capital investment, and processing capacity rather than reagent supply.
Treating Acid as a Hard Constraint, Not a Cost Line
The analytical shift that mining analysts are now calling for is a meaningful one. For most of the industry's operational planning history, sulphuric acid has been treated as a variable cost: a reagent that must be purchased, priced into operating budgets, and managed through procurement. What the current episode has demonstrated is that acid is better understood as a production constraint, analogous to ore grade or water availability, rather than simply a line on a cost spreadsheet.
The distinction matters because constraints and costs require different management responses. If acid is a cost, the response to rising prices is to renegotiate contracts, seek alternative suppliers, or absorb the margin impact. If acid is a constraint, the response is to monitor supply security as a separate discipline, maintain inventory buffers, diversify feedstock sources, and make capital investment decisions, including smelter integration, that reduce procurement dependency. The two approaches lead to very different corporate structures and risk profiles over time.
Analysts at S&P Global CERA put it plainly in a recent note: "What is usually a low-profile industrial chemical is now acting as a binding constraint across both agriculture and metals processing." The framing of sulphuric acid as a binding constraint rather than a temporary inconvenience is reinforced by its supply inelasticity. Sulphur is a byproduct of hydrocarbon processing and oil refining. No producer increases sulphur output because sulphur prices have risen. Recovery rates are a function of refinery throughput and hydrocarbon sulphur content, not commodity market signals. Higher acid prices do not bring forward new acid supply in the way that higher copper prices might eventually bring forward new copper mine capacity. This makes the current squeeze resistant to the normal market self-correction mechanisms.
For mining companies operating in acid-dependent processing environments, the practical implication is that risk management frameworks need to extend further upstream than they typically have. Monitoring sulphur feedstock availability, tracking the distinction between burner acid produced from elemental sulphur combustion and smelter byproduct acid from concentrate processing, and maintaining visibility on multiple potential disruption points along the supply chain are now baseline requirements, not specialist functions. The Zambian export ban, the Hormuz closure, and the Chinese export ban each individually would have been manageable. Together, because they struck simultaneously, they exposed the absence of that upstream monitoring in acute and costly ways.
What Comes Next
The near-term picture for Copperbelt acid supply is marginally better than it was in April, but remains tight. Zambia's partial reversal in May 2026, authorising Chambishi Copper Smelter and Mopani Copper Mines to resume limited exports, offers some relief, though volumes have not been specified publicly and the government has made clear that the domestic market takes priority. China's export ban was initially announced through August 2026; any extension or modification will be closely watched by SX-EW operators in Chile, Indonesia, and the DRC alike.
Kamoa-Kakula's acid output will continue to grow as the smelter ramps toward its design capacity, with full throughput expected around 2028. The 600,000 to 700,000 tonne annual capacity that Marna Cloete cited at CESCO Week would, if achieved, represent a significant contribution to regional supply, though it will still cover only around a third of DRC leaching demand. The six current offtakers purchasing at the mine gate suggest the commercial structure is already in place to absorb that volume locally.
The broader structural question is whether this episode accelerates investment in smelter integration across the Copperbelt. The financial case for integration has always been present, but the acid crisis has made the strategic case far more visible. As I have reported in earlier coverage of the IEA's 2026 Critical Minerals Outlook, government pledges and bilateral agreements have not yet produced meaningful diversification at the processing level. The same logic applies here: policy statements about supply chain resilience will not, by themselves, build smelting capacity or acid capture infrastructure. Capital allocation decisions made now, informed by a realistic assessment of reagent risk, are what will determine whether the Copperbelt's next acid shock catches producers equally exposed.