Extended Mopani and Chambishi smelter outages set to tighten Zambia's acid supply

Two of Zambia's biggest copper smelters, operated by Mopani Copper Mines and Chambishi Copper Smelter, will shut for longer-than-normal maintenance this year, industry sources told Reuters on 20 April, raising the prospect of lower refined copper output and scarcer sulphuric acid across the Central African Copperbelt.

The shutdown timetable

Zambian smelters usually stop for about 30 days a year for routine work. This year both plants face longer outages. According to a mining executive cited in the report, Mopani is scheduled to close for three days in June and then for roughly 40 to 45 days between August and mid-September. A chemicals trader said Chambishi, which is 85% owned by China Nonferrous Metal Mining Group, would go offline for about two months running into August.

The same executive said Mopani is working well below its finished copper capacity of 225,000t a year because years of under-investment left it short of concentrate, and that majority owner International Resources Holding of Abu Dhabi is developing and mining at the same time, causing intermittent stoppages.

An acid squeeze

The timing is awkward. Zambia's smelters produce around 2 million tonnes of sulphuric acid a year as a by-product, according to the mines ministry, most of which is consumed by local mines leaching oxide ores. Surplus has historically been exported to the Democratic Republic of Congo, where copper and cobalt miners depend heavily on imported acid.

That trade had already been disrupted. The war involving Iran has cut supplies of sulphur and leaching chemicals globally, forcing some Congolese producers to reduce usage or consider cutting output. In April Zambia tightened its controls on acid exports, requiring traders to obtain permits in order to protect domestic industry.

Anthony Mukutuma, First Quantum Minerals' country director in Zambia, told Reuters the controls were fair but that exports were unlikely in the near term because local stocks were so low.

Implications

For Zambia, longer smelter outages mean more concentrate waiting to be processed and less refined metal to export, at a time when the government is trying to lift annual output from last year's 890,346t towards 1 million tonnes. For the DRC, the loss of Zambian acid adds to the pressure on operations that rely on solvent extraction and electrowinning.

The outages also highlight a structural issue: the region's acid supply is tied to smelter availability. When smelters stop, both refined copper and the chemical needed to make more copper disappear at the same time.

Sources

• Business Day (Reuters): Zambia smelter shutdowns threaten copper output and sulphuric acid supply, 20 Apr 2026
• CNBC Africa (Reuters): Zambia's copper smelters plan extended shutdowns, squeezing output and chemical supplies, 20 Apr 2026

Photo: The Black Mountain slag heap at Kitwe on Zambia's Copperbelt. Chaze Hamududu, Wikimedia Commons, CC BY-SA 4.0.