A September 15 report from GEM Mining Consulting estimates that a 90-day disruption at the Bab el-Mandeb Strait could affect between 38.9 and 77.8 million tonnes of commodity and input flows, with sulfuric acid, explosives feedstock, and battery materials among the most exposed. At the same time, the Strait of Hormuz has collapsed to just 7 to 10 commodity vessel transits per day against a normal average above 125, pushing more than 4.3 million TEU of shipping capacity into port queues globally. Together, the two disruptions are reshaping mine operating costs in ways that extend well beyond the energy price shock most analysts initially focused on.
Introduction
Two of the world's most important maritime chokepoints are simultaneously under severe stress, and the consequences for mining operations are no longer a future risk to be modelled. They are a present cost being absorbed right now by mines, smelters, and processing plants that depend on seaborne inputs to keep running.
The Strait of Hormuz, which connects the Persian Gulf to the Gulf of Oman, has seen commodity vessel transits fall to between 7 and 10 per day, against a pre-war average of more than 125. The Bab el-Mandeb Strait, the narrow waterway at the southern entrance to the Red Sea, is now effectively under Houthi military control following a rapid territorial advance that completed in mid-September 2026. A September 15 report from Chile-based GEM Mining Consulting quantifies what that combination means for the materials that mines need to operate: the central scenario puts 61.1 million tonnes of commodity and input flows at risk over a 90-day disruption window.
This article explains what the GEM analysis found, why sulfuric acid is the most acute pressure point, what simultaneous closure of both straits does to shipping logistics, and what the outlook looks like through the end of 2026.
What GEM Mining Consulting Found
GEM Mining Consulting, headed by Juan Ignacio Guzman and based in Chile with offices in Singapore, published its preliminary assessment on September 15 via Mining.com. The firm modelled 15 commodity and input families and found that a 90-day disruption around Bab el-Mandeb could affect between 38.9 million and 77.8 million tonnes of flows, with a central scenario of 61.1 million tonnes. Mine production potentially exposed to input delays ranges from 0.8 million to 13.8 million tonnes, while delayed demand ranges from 12.6 million to 33.7 million tonnes.
The report is careful about what it is measuring. The primary threat to miners is not the direct loss of ore shipments but the disruption working through freight rates, insurance costs, inventory buffers, and the chemicals and materials mines need to keep processing plants running. Roughly 10 percent of global maritime trade passes through Bab el-Mandeb, and that share has grown in recent months because Saudi Arabia has been redirecting crude oil through the Red Sea while Hormuz remains constrained.
GEM flags acids, fertilizers, battery inputs, and fuels as the most vulnerable input categories. The recommendation for medium-term relief is structural: more local production, better contract coverage, sulfur-burning plants in India, captive acid from copper and zinc smelters, larger storage capacity in Chile, and new African reagent plants from 2027 onward. For 2026, GEM says the market watch list should focus on whether Beijing enforces a full halt or a quota system on sulfuric acid exports, whether Middle East sulfur flows normalize, and how fast Chile can replace cargoes previously sourced from Peru, Japan, and South Korea.
The Sulfuric Acid Problem: A Chemistry Lesson With Real Stakes
Sulfuric acid is not a specialty chemical used in niche applications. As Freda Gordon of Acuity Commodities puts it, it is "the king of chemicals because it's used in so many different applications." For mining specifically, it is the workhorse reagent in processing copper, lithium, cobalt, nickel, rare earths, and phosphoric acid. Without it, ore goes unprocessed.
The supply shock here has two compounding causes. The Middle East region supplies around one quarter of global sulfur, and nearly half of all seaborne sulfur trade passes through the Strait of Hormuz. Sulfur is the feedstock for sulfuric acid. When Hormuz closed to normal commercial traffic on February 28, 2026, that sulfur supply chain broke. China, which had been a major exporter of sulfuric acid (exports reached 3.89 million tonnes in the first ten months of 2025 alone), responded in May 2026 by suspending exports to protect its own supply. GEM describes the global shock as "the removal of export tonnes from the seaborne market rather than a rise in Chinese import demand."
The price consequences have been severe. Benchmark Mineral Intelligence reports that sulfur prices have climbed more than 50 percent since the conflict began, while sulfuric acid prices have more than doubled in some regions. Spot acid prices in Indonesia have climbed above $380 per tonne and above $440 per tonne in Chile. In hard-rock lithium processing, sulfuric acid now accounts for approximately 11 percent of operating costs, up from around 3 percent before the disruption. That single input has become the largest cost component in lithium refining.
Will Talbot, Benchmark's research manager for raw materials, has been direct about the downstream risk: "The outstanding risk is that more critical minerals players cut production or even shut down operations entirely." Benchmark analysis shows that over half of lithium, cobalt, rare earths, and purified phosphoric acid production in 2026 is exposed to sulfur and sulfuric acid market shocks. For high-purity manganese sulfate monohydrate, used in manganese-containing batteries, 100 percent of supply is exposed.
The Hormuz Collapse and the Cape of Good Hope Detour
The Strait of Hormuz has been in crisis since Iran closed it to normal commercial traffic on February 28, 2026, following US and Israeli strikes on Iran. By early May, more than 1,550 commercial vessels and approximately 22,500 mariners were reported trapped in and around the strait. Traffic ran at roughly 5 percent of its pre-war average through April. A US-Iran ceasefire in early April, followed by a memorandum of understanding in mid-June, nominally reopened the strait by around June 17, but traffic has remained far below normal.
As of mid-September 2026, commodity vessel transits are running at 7 to 10 per day. Ship-tracking data from Kpler recorded just four commodity vessels transiting on September 18: two Panamax tankers, one supramax ship, and one Kamsarmax vessel. That is a 94 to 96 percent reduction from the pre-war average of more than 125 daily transits. Some vessels are switching off transponders during transit to avoid detection, which means the true picture may differ from tracking data, but the directional evidence is unambiguous.
US Central Command's Admiral Brad Cooper stated that the US military has cleared Iranian sea mines from the strait's internationally recognized shipping lanes. The shipping industry, however, remains skeptical that no mines remain, and carriers are not yet resuming normal schedules. The result is that most vessels have taken the long way around: the Cape of Good Hope route, which adds roughly 3,500 to 4,000 nautical miles and 10 to 14 extra days to Asia-Europe and Asia-Middle East voyages.
The rerouting has cascaded into port congestion. Cape Town has seen a 112 percent surge in vessel calls. Rotterdam and Antwerp-Bruges are experiencing increased dwell times as diverted vessels arrive in bunches rather than on predictable schedules. Port Said faces waits of 5 to 10 days. According to Linerlytica data, more than 4.3 million TEU of containership capacity is currently waiting to berth globally, exceeding the approximately 4.0 million TEU peak recorded during the 2022 disruption. Effective global fleet capacity absorption from congestion alone represents 6 to 8 percent of total capacity locked up at anchorage.
Bab el-Mandeb: Geography, Houthi Control, and the Dual Chokepoint Bind
Bab el-Mandeb sits at the southern entrance to the Red Sea, a narrow passage only about 20 miles wide connecting the Red Sea to the Gulf of Aden and, from there, to the Indian Ocean. The western channel, used by international shipping, is roughly 16 miles across. It is the only direct maritime access to the Suez Canal, which is the main link between Europe and Asia.
The Houthi military advance in September 2026 transformed the strait from a contested zone into an effectively controlled one. On September 10, Houthi forces seized Mocha, a strategic port city on Yemen's southern Red Sea coast. The following day they pushed south, capturing Yemen's remaining Red Sea coastline and Perim Island, which sits inside the chokepoint itself. The Houthis also seized the Hanish Islands, roughly 100 miles north of the strait. By mid-September, their forces had advanced to within approximately 20 miles of the US military base in Djibouti.
Ana Subasic, a trade risk analyst at MarineTraffic, notes that the Houthi capture of Perim "does not itself amount to full control of Bab el-Mandeb, but it materially increases the group's geographic leverage over the approaches to the strait." Caroline Rose, Senior Director at the Soufan Center, has been more blunt: the Houthi takeover "creates a chokehold which will force shipping operators to reconsider costlier alternatives" and replaces the Red Sea and Suez Canal route with "a much more onerous path through Asia, the Cape of Good Hope, the Atlantic, then to Europe."
Nada Sanders, Distinguished Professor of Supply Chain and Information Management at Northeastern University, describes the combined disruption in terms that are worth holding onto: "Hormuz is the greater stand-alone oil shock. Bab el-Mandeb is the broader trade and logistics shock." When both close simultaneously, the consequences compound rather than simply add. Sanders estimates the dual closure, combined with the shutdown of the East-West Crude Oil Pipeline on September 11, has resulted in total disruption of 39 percent of global trade and 31 percent of global shipments. That is, as she puts it, a "supply shock with no modern historical precedent in terms of combined rerouting constraints."
What This Means for Mine Operating Costs
The freight cost escalation from Cape rerouting is already flowing through to mining operations in measurable ways. Freight rates have jumped 30 to 50 percent on affected lanes. Fuel surcharges are up 15 to 25 percent because the longer route burns more bunker fuel. War-risk and conflict surcharges, which were zero for most cargo operators before February 2026, now run between $200 and $800 per container depending on origin port and lane. For an ultra-large container vessel valued at $150 million, a single transit through a conflict-adjacent zone can add more than $1 million in insurance premiums, costs that carriers pass downstream immediately.
Port congestion surcharges have been added on top. Current hotspot rates run from $300 to $600 per container on the US East Coast, $400 to $800 in Europe, and $400 to $700 in Latin America. For mines sourcing reagents, replacement parts, and explosives feedstock from multiple continents, these are not line items that can simply be absorbed. They compound with the sulfuric acid price spike described earlier, with elevated energy costs from the oil shock, and with the longer lead times that force mines to carry larger inventories at greater carrying cost.
PortXchange, the Rotterdam-based port optimization platform, has been tracking the congestion buildup closely. Managing Director Sjoerd De Jager has characterized the core problem as coordination failure rather than pure capacity shortage: shipping lines, terminals, pilots, and agents are working from different data sets, and decisions made too late mean ships arrive simultaneously and queue. PortXchange analysts expect congestion to remain elevated until at least November 2026 and anticipate that shipping lines will formalize congestion surcharges in the weeks ahead. Their practical advice to freight-dependent businesses is to book early, build in a buffer of 7 to 10 days, and maintain close relationships with freight forwarders who can see across multiple port options.
What to Watch Through the End of 2026
The near-term outlook depends on several variables that are genuinely uncertain. On Hormuz, US mine-clearing claims have not yet translated into a meaningful resumption of commercial traffic, and the shadow voyage system that has developed (involving preapproved routes, intermediary coordination, and in some cases additional fees paid to Iranian authorities) concentrates risk onto a small pool of willing operators rather than restoring normal market function. That is not a stable equilibrium.
On Bab el-Mandeb, the Houthis' declaration that maritime navigation is safe for all companies except Saudi ships may provide partial relief for non-Saudi cargo, but the operational reality of moving vessels through a strait where one side is controlled by an armed group with a history of missile and drone attacks is a different matter from a formal statement of intent. Insurers and carriers will set their own assessments, and those assessments will determine whether the strait reopens in practice.
For critical minerals supply chains specifically, the GEM watch list is a reasonable framework for tracking developments: Beijing's decision on whether to enforce a full halt or a quota system on sulfuric acid exports, whether Middle East sulfur flows normalize as the conflict evolves, and whether Chilean buyers can realistically diversify sourcing away from Peru, Japan, and South Korea. Battery-grade lithium carbonate prices in China have already risen approximately 65 percent in US dollar terms this year. If acid availability tightens further and production curtailments follow, those price signals will reach battery manufacturers and, eventually, consumers.
As I noted in my September analysis of the GEM Bab el-Mandeb exposure report, maritime chokepoint vulnerability has been the most underpriced systemic risk in critical mineral supply chains. The September 2026 data does not change that assessment; it confirms it at a scale that is harder to dismiss. The structural medium-term fixes that GEM recommends, including local acid production, captive smelter output, and expanded storage, are sensible but will take years to build. In the meantime, the cost of two blocked straits is being paid, one surcharge at a time, by the mines and processors that sit at the base of the energy transition supply chain.