China banned a smelting byproduct and closed copper mines in Chile and Congo
A fertilizer panic in Beijing reached into the Atacama and the Congolese copperbelt, and the metal that feeds Chinese smelters stopped moving first.
On April 10 this year, China replaced a 700,000-tonne annual quota on sulphuric acid exports with a complete ban running through August, keeping the acid at home for fertilizer production after Middle East fighting squeezed the sulphur feedstock it is made from (Kpler research note, Jun 4). Sulphuric acid sounds like a footnote. It is the working fluid of modern copper mining: pour it over crushed oxide ore and copper dissolves out into collection ponds. Without it, some of the world's biggest mines simply stop producing.
The mines that stopped are not in China. In Chile, roughly 1.2 million tonnes of annual copper output is considered vulnerable to the acid squeeze, and for some leaching projects acid has climbed to a third of operating cost (Skillings Mining Review, Jul 19 and Jul 22). In the Democratic Republic of Congo, about 45% of copper production depends on acid leaching, exposing roughly 1.5 million tonnes of output (Critical Minerals News, Jul 21). Industry estimates put up to 450,000 tonnes of global copper production at risk in 2026 if the shortage persists (Skillings Mining Review, Jul 22). Analysts figure that 100,000 to 200,000 tonnes of refined copper could be lost this year alone as operators curtail leach cycles or delay ramp-ups (Skillings Mining Review, Jul 24).
Then the triggers stacked. On August 4, Codelco suspended development work at Andes Norte, part of the expansion of El Teniente, the world's largest underground copper mine, citing seismic studies showing more risk than believed, one year after a collapse at the same complex killed six workers (Codelco press release, Aug 4; Reuters via Mining Weekly, Aug 5). The precautionary halt touches around 3,100 workers (Mining Reporters, Aug 12). Two days later Kinshasa banned all exports of copper and cobalt concentrate, ordering miners to process at home under a new by-product tax regime with a three-month transition (Reuters, Aug 6). Three separate shocks, three different capitals, one direction: less copper reaching the market this year.
China banned acid to protect its fertilizer crop and starved its own smelters of the ore they were already paying to receive.
Here is the part that should trouble Beijing. China runs the world's largest copper smelting fleet and those smelters were already starving for ore before the acid ban made it worse. The economics had broken so badly that China's ten biggest smelters, grouped in the CSPT, voted to cut their own output by more than 10% this year (Mining.com, Nov 28, 2025). By banning acid exports, Beijing shut down ore producers abroad who supply the very smelters it wants to keep running. The state protected fertilizer plants and injured its own metal industry in the same signature.
The actors want incompatible things. Beijing's agriculture ministry wanted fertilizer security during a war-driven sulphur shortage; its smelters wanted maximum feedstock; its buyers wanted cheap refined copper for grids and data centers. Santiago wants volume: Codelco needs El Teniente's expansion to offset aging deposits, but cannot send workers back onto active faults. Kinshasa wants value captured at home, following the playbook Indonesia used for nickel ore, and President Félix Tshisekedi's government is betting that Glencore, CMOC and Ivanhoe Mines will build Congolese smelters rather than abandon the orebody. Each government made a rational choice. Together they subtracted supply from a market where demand from electrification and AI data centers keeps climbing.
History gives one clean comparison. Indonesia banned raw nickel ore exports in 2020, forced Chinese capital to build Indonesian smelters, and ended up controlling far more of the battery-metal chain than anyone predicted. That is the bet Kinshasa is making with copper concentrate. The counter-example argues the other way: nickel smelters run on cheap coal-fired power Indonesia had in abundance, while Congolese copperbelt smelting is throttled by electricity shortages and a thin rail corridor to the coast, and the DRC's own last attempt at a concentrate ban, in 2013, was quietly dropped within months when smelter capacity failed to appear. Indonesia converted a ban into industry. Congo risks converting a ban into idled mines.
Follow who pays and when. Spot buyers bid first: fabricators in Asia and Europe least able to shop around chase cathode in a thinner market and pay up for it. Then the mid-tier Chilean leach operators without long-term acid contracts curtail, exactly what S&P Global analysts warned would happen when they found Chilean buyers had covered only the first half of 2026 (S&P Global Platts, Apr 21). The margin collects at the top, with whoever still owns integrated mine-to-smelter capacity. Glencore and Ivanhoe sit closest to that position in Africa; Codelco's pain is Chile's fiscal pain, since the state company funds the budget.
Watch what confirms or breaks this. If the read is right, Chinese customs data shows concentrate imports falling in the third quarter even as smelters beg for feed, and spot treatment charges stay below zero past November's benchmark talks. If the ban lapses in September as scheduled and Chinese acid cargoes reappear in Antofagasta and Durban within weeks, the whole episode compresses into a scare, and the copper price gives back its risk premium.
What absorbs the consequence, in the end, is physical: the heaps in the Atacama waiting for acid that has not arrived, the flooded galleries under El Teniente where six men died doing expansion work the country needed, and the Lubumbashi households breathing the dust of mines that Kinshasa now says must process at home. This year the supply curve was redrawn by a fertilizer clerk in Beijing, a seismograph in the Andes, and a minister's pen in Kinshasa.