China's Copper, Zinc, and Lead Smelters: Overcapacity, Zero TCs, and the Byproduct Pivot

China's copper smelting capacity has consistently outrun growth in global mine supply, producing a concentrate deficit estimated near 850,000 tonnes in 2025 and driving the 2026 annual treatment-charge benchmark to zero, the lowest on record, while spot imported lead and zinc charges turned deeply negative. Sulphuric acid, once a secondary stream, now accounts for a majority of operating revenue at some Chinese copper smelters, and a 2026 restriction on acid exports introduces a new variable in global industrial-acid supply. Industry bodies announced output cuts above 10% in late 2025, but member guidance into early 2026 showed limited implementation. This report examines the capacity build, the economics of zero-fee smelting, byproduct dependence, proposed capacity caps, and the effect on global concentrate trade.