Cadmium: Extraction
Why nobody mines cadmium, yet thousands of tonnes appear
What this tab covers How it is mined, drilled or grown, and processed into a tradeable form: the main methods compared, their unit economics, by-products, and the companies that do this work globally and in India.Cadmium substitutes for zinc in sphalerite, the main zinc ore. Typical zinc ores carry about 0.03% cadmium, so nobody mines for it. At zinc smelters, cadmium is removed while the zinc solution is purified. It is either recovered as metal or treated as waste. About 95% of supply is a by-product. In the US, one Tennessee zinc smelter produced about 200 t in 2025. Secondary cadmium comes mainly from spent NiCd batteries, plus electric-arc-furnace dust and old CdTe panels.
Cadmium is a by-product of zinc. Every zinc smelter that uses the roast-leach-electrowin route has to remove cadmium from its solutions, because it would spoil the zinc. Smelters then either refine it into saleable metal or store and dispose of it as hazardous waste. So cadmium supply is set by zinc smelting, mostly in China and Korea, and does not respond to cadmium prices. A second source is recycling, chiefly of industrial NiCd batteries. Because uses are shrinking and cadmium is toxic, the market is small and prices are low.
Methods compared
| Method | Share of supply | Typical scale | Recovery / efficiency | By-products | Unit cost |
|---|---|---|---|---|---|
| By-product of zinc refining (solution purification) | nearly all primary cadmium (USGS Circular 1365; USGS 2026) | US: one Tennessee zinc smelter made about 200 t in 2025; world refined 23,000 t (USGS 2026) | A substantial but unquantified amount is lost to waste when prices are low (USGS Circular 1365) | zinc is the host; germanium, indium, copper and cobalt from the same circuits | n/a |
| Recycling of NiCd batteries and other cadmium scrap | about 20% of world supply in 2008 (about 4,000 t of 19,600 t, USGS Circular 1365) | n/a | EU end-of-life recycling input rate 30% (EU CRM 2023) | nickel, iron | n/a |
How each method works
By-product of zinc refining (solution purification)In electrolytic zinc plants, zinc dust cements cadmium out of the leach solution as a sponge. The sponge is redissolved and cadmium electrowon, or melted and distilled, to 99.95-99.99% metal. In older pyrometallurgical plants, cadmium collects in fumes and is recovered from dusts.
Removal is required anyway, so marginal cost is low; when prices are weak, smelters may store cadmium rather than sell it.
USGS MCS 2026; USGS Circular 1365 (2010) Recycling of NiCd batteries and other cadmium scrapSpent consumer and industrial NiCd batteries are collected, and cadmium is distilled off in high-temperature furnaces and recovered as metal. Copper-cadmium alloy scrap, electric-arc furnace dust and CdTe panels are also processed. One Ohio company recovers cadmium from NiCd batteries (USGS 2026).
Removes a toxic metal from waste; volumes will fall as NiCd use declines.
USGS MCS 2026; USGS Circular 1365 (2010); EU CRM 2023 Unit economics are indicative ranges from the sources named; costs vary widely by deposit, region and year.By-product supply
Companionality is about 95%: cadmium comes from zinc concentrates and will be extracted from ore whatever cadmium demand is, because zinc is mined for its own value (Nassar et al. 2015). When demand is weak, the cadmium is not destroyed: it builds up in smelter stocks or waste. That makes supply price-inelastic and keeps prices low, about $3.90/kg in 2025 (USGS) against $2.87/kg ($2,868/t) for zinc (World Bank 2025).
Share produced as a by-product
About 95% of primary supply comes as a by-product of zinc (Nassar, Graedel & Harper 2015, approximate).Who does it: global
| Company | Country | Activity | Volume | Year | Source |
|---|---|---|---|---|---|
| Chinese zinc smelters (country total) operator volumes not published | China | zinc smelting with cadmium recovery | 9,500 t Cd (country refinery output) | 2025e | USGS MCS 2026 |
| Korea Zinc not published; Korea Zinc is Korea's main zinc smelter | South Korea | zinc smelting with cadmium recovery (Onsan) | not published | 2025 | USGS MCS 2026 (Korea output 4,300 t) |
| Nyrstar (Clarksville, Tennessee; Trafigura group) | US | zinc smelting with cadmium metal by-product | 200 t Cd | 2025e | USGS MCS 2026 (one company's Tennessee smelter; Clarksville named in USGS Germanium chapter) |
| Nyrstar (Budel smelter) not published | Netherlands | zinc smelting with cadmium recovery | not published | 2025 | USGS MCS 2026 (Netherlands output 600 t) |
| Boliden (Odda smelter) not published | Norway | zinc smelting with cadmium recovery | not published | 2025 | USGS MCS 2026 (Norway output 430 t) |
| Japanese zinc smelters (country total) operator volumes not published | Japan | zinc smelting with cadmium recovery | 1,300 t Cd (country refinery output) | 2025e | USGS MCS 2026 |
| First Solar (buyer) cadmium volume not published | US | largest CdTe module maker | 14 GW/yr expected US capacity | 2026 | USGS MCS 2026 |
Who does it: India
| Company | Country | Activity | Volume | Year | Source |
|---|---|---|---|---|---|
| Hindustan Zinc (Vedanta group) not published; cadmium is listed among the company's products | India | zinc smelting at Chanderiya, Debari and Dariba with cadmium as a by-product; 827 kt refined zinc in FY2025 | not published | FY2025 | Hindustan Zinc Integrated Report FY2024-25 (cadmium volume not reported) |
India's cadmium comes from Hindustan Zinc's smelters, which made 827 kt of refined zinc in FY2025, but no cadmium tonnage is published and USGS's world table omits India. India charges royalty on primary cadmium at 4% of its average sale price (IBM yearbook 2023).