When the Strait of Hormuz closed to commercial dry bulk traffic on February 28, 2026, the immediate casualty was not shipping schedules but the chemical input that makes copper and cobalt mining possible across central Africa. Four simultaneous sulfur supply impairments have converged on the Copperbelt, forcing Ivanhoe Mines to revise production guidance downward, doubling diesel trucking costs in Zambia, and putting up to $1.1 billion in cobalt exports at risk. The episode reveals a supply chain feedback loop that conventional freight-cost analysis almost never captures.
Introduction
This story matters to anyone tracking the supply of copper and cobalt into electric vehicle batteries, renewable energy infrastructure, or defense electronics. The Copperbelt spanning the Democratic Republic of Congo and Zambia is the single most concentrated source of both metals on earth, producing roughly 70 percent of global mined cobalt and a fast-growing share of global copper. When something disrupts its ability to operate, the effects move quickly through supply chains that reach into factories in South Korea, Germany, and the United States.
The disruption that began in late February 2026 did not start in the Copperbelt. It started in the narrow waterway between Iran and Oman. On February 28, the Strait of Hormuz closed to commercial dry bulk traffic following the military operation known as Operation Epic Fury and subsequent Iranian retaliation. Most coverage of that closure focused on oil prices and fertilizer shipping. Far less attention went to sulfur, a by-product of oil and gas processing that quietly underpins one of the most important steps in modern copper production.
What followed was not a single supply shock but four overlapping ones, arriving in the same quarter and hitting the same geographic pressure point. Building on my earlier analysis of how the Hormuz disruption was squeezing the Copperbelt from multiple directions simultaneously, this piece examines the full scope of what has now become the most acute sulfur and sulfuric acid supply crisis the central African mining sector has faced in over a decade, and what it means for copper and cobalt output going forward.
How Sulfur Becomes a Mining Crisis
To understand why a maritime chokepoint in the Persian Gulf can halt copper production in central Africa, it helps to trace the chemical chain from beginning to end. The Copperbelt's dominant copper extraction technology is solvent extraction-electrowinning, or SX-EW. This process works by applying sulfuric acid to crushed oxide ore, dissolving the copper ions, and then recovering them electrolytically. There is no practical short-term substitute for sulfuric acid in this process. Impure acid degrades extraction efficiency, and recovery rates fall sharply when purity drops below 90 percent. Mining operations cannot simply accept an inferior product during a supply emergency.
Sulfuric acid is produced by burning elemental sulfur in a conversion plant. Sulfur accounts for roughly 80 percent of the acid's production cost, which means a sulfur price shock passes almost directly into the price of the acid. The Copperbelt imports approximately 2 million tonnes of sulfur per year, producing around 6 million tonnes of sulfuric acid annually for oxide copper leaching, with an additional 2.5 million tonnes generated by regional copper smelters processing concentrates. Roughly 90 percent of that imported sulfur originates in the Middle East, because Gulf oil and gas processing generates sulfur as a by-product at massive scale and at competitive cost.
The Strait of Hormuz normally handles approximately half of global seaborne sulfur trade. When it closed, the Copperbelt's primary supply corridor closed with it. Sulfur prices at the key regional hub of Dar es Salaam, Tanzania, the main entry port for Copperbelt-bound materials, surged from around $600 per tonne before the conflict to offers above $1,000 per tonne, with some small-parcel quotes reaching $1,200. The logistics cycle for chemical orders, which previously ran about three months, stretched to four to six months. Ivanhoe Mines founder and executive co-chairman Robert Friedland put the operational reality plainly: "If the disruption lasts longer than approximately three weeks, copper oxide operations will have to close as they've run out of acid."
The Four-Way Convergence
What made the first half of 2026 historically unusual was not just the Hormuz closure but the simultaneous arrival of three additional supply impairments, each of which would have been a meaningful market event on its own.
Russia's sulfur export ban, originally imposed in November 2025 and extended through the end of 2026, removed a significant alternative source from the market. The extension was driven partly by drone strikes targeting the Astrakhan facility, which produces nearly 60 percent of Russia's sulfur, pushing domestic output down roughly 19 percent in the first five months of 2026 compared to the same period in 2025. Turkey, facing a 35 to 40 percent surge in domestic sulfur prices, imposed its own export restriction covering the second and third quarters of 2026, putting approximately 160,000 tonnes of annual export volume on hold.
The fourth and arguably most consequential impairment was China's decision to halt sulfuric acid exports. Beijing had already cut export quotas sharply in early 2026, approving only 700,000 tonnes for the January to April period compared to 1.3 million tonnes in the same window in 2025. Then, effective May 1, China suspended all exports of ordinary industrial sulfuric acid entirely, retaining only electronic-grade high-purity acid under a special approval process. China produces more than 40 percent of global sulfuric acid output, and its exports had surged 73 percent in 2025 to 4.65 million tonnes, making it a critical flexible valve for global spot markets. With that valve closed, buyers who might otherwise have substituted Chinese acid for unavailable Gulf sulfur had nowhere to turn.
As ING's chief economist for Greater China, Lynn Song, explained: "Administrative controls are expected to amount to a de facto suspension of sulphuric acid exports from May 2026. The intention would be to secure fertiliser supply, which is currently at risk thanks to the blockage of the Strait of Hormuz." Syed Salman Shaffi, president of the Gold Miners Club, framed Beijing's action in starker terms: "China's export halt acts as a crisis multiplier. The Iran conflict created a shortage of raw materials. China's export suspension triggers a commercial drought. These events shift the burden from Chinese smelters to copper and cobalt mining operations in Congo and fertilizer blenders in India."
The four impairments together, the Hormuz closure, Russia's ban, Turkey's restriction, and China's acid suspension, produced what analysts described as the most acute sulfur supply disruption in a generation. Global sulfur exports fell 45 percent below end-February levels. In the first quarter of 2026, sulfuric acid imports across the region dropped from 113,000 tonnes to just 29,200 tonnes.
Ivanhoe's Revised Guidance, Doubled Trucking Costs, and the Cobalt Quota Failure
The most visible corporate signal of the crisis came from Ivanhoe Mines, whose Kamoa-Kakula complex in the DRC is the largest copper mine in Africa. Ivanhoe entered 2026 with guidance of 380,000 to 420,000 tonnes of copper for the year. By March 31, that guidance had been cut to 290,000 to 330,000 tonnes. By the time Q2 2026 results were released in late July, the range had tightened further to 290,000 to 310,000 tonnes. The mine's on-site smelter, the largest copper smelter on the continent, has been operating at approximately 60 percent of design capacity since mid-February. Goldman Sachs analysts estimated that up to 125,000 tonnes of DRC copper could be at risk across the sector if the crisis continued.
The input supply problem was compounded by a diesel crisis running through the same causal chain. The Strait of Hormuz handles a large share of the region's diesel imports as well as its sulfur exports, and Southern Africa felt the physical effects quickly. In Zambia, a major distributor priced diesel at $2.41 per litre by mid-2026, almost exactly double the pre-crisis level of $1.21 per litre in February. Special excise taxes added further pressure: the fully taxed cost in some cases reached $3.38 per litre. Since mining supplies and ore concentrates move by truck across road networks spanning nearly 3,500 kilometres to ports in Dar es Salaam or Durban, that doubling of fuel costs hit both inbound chemical logistics and outbound metal exports simultaneously.
The backhauling model that links cobalt exports to sulfur imports deserves particular attention here. Trucks carrying cobalt concentrates outbound from the DRC to Dar es Salaam ideally return inbound with sulfur or acid. Inspection bottlenecks and diesel shortages from the Hormuz closure disrupted that return leg, tightening both flows at once. The system is interdependent in ways that point estimates of freight-cost increases do not fully reflect.
Separately, an administrative failure at the DRC's strategic minerals regulator, ARECOMS, threatened to compound the production crisis with an export crisis. ARECOMS had set a July 5 deadline for producers to use their first-half cobalt export quotas, after which unused volumes would be withdrawn and reallocated. The Congo Chamber of Mines wrote to ARECOMS on July 2 flagging that producers had been unable to register export declarations on the customs platform since July 1, due to the absence of a formal notification from ARECOMS authorising customs to continue processing. Between 60 and 75 percent of companies were reportedly unlikely to meet the deadline because of the administrative blockage. The result, according to reporting by Reuters, was a threat to as much as 20,000 metric tonnes of cobalt shipments worth $1.1 billion at current prices. Cobalt had already risen from approximately $21,000 per tonne in early 2025 to over $56,000 per tonne by mid-2026, a 167 percent appreciation driven in large part by the DRC's earlier export quota regime.
The Feedback Loop Conventional Analysis Misses
The episode illustrates a supply chain transmission mechanism that standard freight-cost models are not built to capture. Conventional analysis of a maritime chokepoint closure typically tracks oil prices, container rates, and shipping lane rerouting costs. Those metrics matter. But the Hormuz closure also disrupted the flow of sulfur, a commodity that travels in dry bulk carriers and whose connection to copper production is invisible in most logistics dashboards.
The transmission chain runs as follows: a chokepoint closure blocks sulfur exports from Gulf producers; that sulfur shortage raises sulfuric acid prices globally; higher acid costs raise operating expenses for SX-EW copper operations in regions without domestic sulfur supply; those operations reduce chemical usage, draw down inventories, and begin cutting production; output of copper and cobalt falls; supply chains for batteries and electronics downstream feel the tightening months later. Each link in the chain involves a different commodity, a different set of intermediaries, and a different regulatory jurisdiction. No single monitoring system spans all of them.
Zambia's response is instructive. Facing depleted domestic acid inventories that threatened its own copper producers, Zambia imposed an outright sulfuric acid export ban in September 2025, later replaced by a permit system in March 2026. The move protected Zambia's own mines but removed one of the few remaining local supply options available to DRC operators. First Quantum Minerals' Zambia head confirmed that the country's acid stocks were so depleted there was effectively no capacity to export. The regional system, in other words, tightened recursively: each actor's protective response reduced flexibility for neighboring operations.
The alternative sources that exist are constrained in ways that compound this picture. Qatari, UAE, and Kazakh sulfur volumes are substantially committed under long-term contracts to India and Morocco. Even when the Strait fully reopens, not all of that supply will reach spot markets, because a meaningful share is already contractually obligated. New sulfuric acid production capacity cannot be built quickly, and the chemical requires specialised transport and storage infrastructure that cannot be improvised. The Copperbelt's structural dependency on Gulf sulfur, built over decades of cost-optimized sourcing, cannot be unwound in one quarter or even one year.
What Comes Next
The immediate question for supply chain professionals and policymakers is whether the overlapping impairments ease before they cause permanent structural damage to Copperbelt output capacity. On the sulfur side, the UAE remained the only Middle Eastern Gulf country still moving sulfur via the Strait as of May 2026, with Kpler tracking only three UAE-sourced transits in that month. Some easing is plausible as the geopolitical situation evolves, but Russia's ban now runs through the end of 2026, China's acid suspension carries no clear end date beyond the current guidance, and Turkey's restriction covers at minimum the third quarter. India has been reported to be considering its own sulfur export restrictions in response to domestic price pressures, which would remove another potential substitute source.
For cobalt, the ARECOMS administrative failure is a reminder that policy risk and process risk compound physical supply risk in the DRC. The quota system introduced after the 2025 export suspension was designed to stabilize prices and revenues, and it has succeeded in driving cobalt from $21,000 to over $56,000 per tonne. But Fastmarkets projects a structural shortfall of approximately 10,700 metric tonnes against 2026 global demand of 292,300 metric tonnes, and any additional administrative disruption tightens that balance further. The DRC produced approximately 100,015 metric tonnes of cobalt in 2025 but exported only 44,333 metric tonnes, meaning more than half of domestic output was withheld from global markets during that period.
For Ivanhoe, the path back to full production is now targeted at 2028, when the company expects annualized copper anode production to return above 500,000 tonnes at a cash cost below $2.00 per pound. Whether that timeline holds depends heavily on how quickly sulfur logistics normalize and whether Kamoa-Kakula's smelter can return to full design capacity.
The deeper lesson of the first half of 2026 is about supply chain architecture rather than any single commodity price. The Copperbelt's 90 percent dependence on Gulf sulfur was not a secret before February 2026; it was simply a risk that had not been priced in, diversified around, or reflected in the stress tests that inform investment and policy decisions. As the IEA, Western governments, and defense procurement agencies accelerate demands for supply chain mapping and resilience, the sulfuric acid story suggests that the critical inputs worth tracking are not always the ones that appear in the final product. Sometimes the constraint lives two or three steps upstream, in a commodity so mundane that it rarely attracts a headline until the day it disappears.