China’s copper smelters, responsible for more than half of global refined output, are facing renewed margin pressure as sulphuric acid prices—a critical revenue-supporting byproduct—fall sharply. The decline comes just months after smelters benefited from unusually strong acid markets, exposing how fragile the economics of the sector have become.
Sulphuric Acid Price Decline Hits Profitability
Sulphuric acid is generated during copper smelting and has historically provided a cushion against volatile treatment and refining charges (TC/RCs). Earlier in 2025, prices spiked due to constrained availability, helping Chinese smelters offset costs. But according to Shanghai Metals Market (SMM), benchmark sulphuric acid prices have retreated since September, dragged lower by weakening demand in the fertilizer sector.
The fertilizer industry, which consumes nearly two-thirds of sulphuric acidhttps://skillings.net/marimaca-copper-sulfuric-acid-plant/ produced in China, has cut purchases amid lower crop prices and high input costs. This demand contraction has pushed sulphuric acid prices back to levels last seen in early 2023, leaving smelters without the buffer they had relied on during the first half of the year.
Smelter Economics Under Strain
The impact of the acid price slump is being compounded by persistently negative spot TC/RCs. Smelters have been forced to accept lower charges from miners as global concentrate supply remains tight, particularly following disruptions in Panama and reduced shipments from South America. With copper concentrate costs high and refining margins compressed, the profitability of Chinese smelters is being squeezed from multiple angles.
SMM’s analysts caution that “the combination of lower byproduct revenues, high raw material costs, and persistently negative spot TC/RCs will deteriorate operating rates.” In practice, this means smelters may cut throughput or delay maintenance restarts, slowing production growth that had previously been running at record pace.
Record Chinese Output Shaping Global Competition
In the first half of 2025, Chinese smelters set new records for refined copper output, flooding the market with cathodes and intensifying competition for international producers. According to customs data, China produced over 6 million tonnes in the period, outpacing previous records and accounting for more than 50% of global refined supply.
This aggressive output put pressure on smelters in Europe, Japan, and Latin America, many of which operate at higher costs and depend on stable TC/RCs to remain viable. A pullback in Chinese operating rates could therefore rebalance margins globally, easing oversupply fears and offering some relief to struggling refiners abroad.
Base Metals Market Context
At 9:45 a.m. London time on Monday, copper on the London Metal Exchange (LME) was steady at $9,978 per tonne. Nickel and aluminum also traded flat, reflecting cautious sentiment across base metals. While copper remains near the psychologically significant $10,000/t threshold, smelter profitability increasingly depends on treatment charges and byproduct markets, rather than outright copper prices.
This underscores a structural challenge: even if copper prices remain firm, smelters can suffer financially if TC/RCs and sulphuric acid revenues collapse. For miners, the current dynamic could bring renewed pressure to improve concentrate supply stability and maintain longer-term TC/RC contracts.
Skillings Analysis
- Margin Squeeze Intensifying: Chinese smelters are operating under some of the most challenging conditions in years, with both TC/RCs and byproduct revenues eroding simultaneously.
- Global Ripple Effects: Any cutbacks in Chinese operating rates could ease competitive pressure on overseas smelters, particularly in Europe and Latin America, where cost structures are more fragile.
- Cross-Sector Dependency: The sulphuric acid market highlights how non-metal sectors such as fertilizers can directly influence smelter economics, adding volatility beyond copper itself.
Outlook
As the fourth quarter progresses, the outlook for China’s copper industry hinges on whether fertilizer demand revives and whether concentrate supply eases. With the Christmas cycle typically marking a period of weaker industrial activity, smelters may further moderate output. Markets will be watching closely: a slowdown in Chinese operating rates could tighten refined supply in early 2026, potentially offering price support for copper and improving margins for non-Chinese producers.
For mining companies and analysts, the key signal to monitor is whether sulphuric acid prices stabilize before year-end. If not, 2026 may begin with a recalibration of global smelting capacity.
