# Selenium: Extraction How selenium hitches a ride with copper Source page: https://www.materialinsights.org/commodities/selenium/extraction/ 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. Selenium is rarely mined for itself. It sits in trace amounts in copper sulphide ores and follows the copper through concentration and smelting. During electrolytic refining of copper anodes it settles in the anode slimes, alongside tellurium and precious metals. Refiners roast or leach these slimes to recover crude selenium, then purify it to 99.5% or better. USGS says more than 80% of all selenium has come from this route. Lead, nickel and zinc ores are minor sources. Coal holds plenty of selenium, but recovery from fly ash is not expected to pay. Selenium is recovered mainly from the anode slimes of electrolytic copper refineries, with smaller amounts from lead, nickel and zinc processing. Supply therefore tracks copper refinery output and how many refineries treat their slimes for selenium. China's selenium output rose sharply as its copper anode capacity more than doubled in ten years. Coal holds large amounts of selenium, but recovery from fly ash is not expected to be economic (USGS 2026). There is meaningful spare refinery capacity, about a third above output. #### Methods compared | Method | Share of supply | Typical scale | Recovery / efficiency | By-products | Unit cost | |---|---|---|---|---|---| | **Recovery from copper refinery anode slimes (roasting or pressure leaching)** | more than 80% of all selenium produced (USGS 2026) | national outputs range from 2,000 t (China) to under 50 t; a new Kazakh plant is designed for about 75 t/yr (USGS 2026) | about 50-60% of the selenium and tellurium in ore is refined to metal; about 4,600 t could have been recovered from slimes in 2008 against output of 3,000-3,500 t (USGS Circular 1365) | gold, silver, tellurium, platinum-group metals | n/a | | **Recovery from lead, nickel and zinc processing** | under 20% (remainder after copper slimes, USGS 2026) | n/a | n/a | mercury, tellurium | n/a | | **Recycling of electronic and photocopier scrap** | insignificant (USGS 2026) | n/a | EU end-of-life recycling input rate about 1% (EU CRM 2023) | n/a | n/a | #### How each method works **Recovery from copper refinery anode slimes (roasting or pressure leaching)** Slimes are mixed with soda ash or sulphuric acid and roasted, or leached under pressure. Selenium leaves as selenium dioxide gas, is scrubbed into solution and reduced with sulphur dioxide to crude red selenium, then distilled. US refineries in Texas and Utah make crude selenium and slimes but do not refine it (USGS 2026). Low incremental cost at an existing refinery; volumes capped by copper refining. USGS MCS 2026; USGS Circular 1365 (2010) **Recovery from lead, nickel and zinc processing** Selenium is captured from acid-plant sludges and residues at some lead, zinc and nickel smelters, often together with mercury and tellurium. Extra supply from existing plants; small and irregular. USGS MCS 2026 **Recycling of electronic and photocopier scrap** Old selenium photoreceptor drums and electronic scrap are processed to recover selenium; volumes have fallen as selenium drums disappeared. Most selenium uses are dissipative (glass, feed, fertiliser), so little can be recycled. USGS MCS 2026; 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%: more than 80% of selenium comes from copper anode slimes. Selenium is worth very little next to the copper, gold and silver in the same slimes, so its own price has no effect on how much copper is refined. Supply responds only through new slime circuits and refinery expansions, mostly in China. Spare capacity of about 1,300 t (5,100 t capacity against 3,800 t output in 2025) softens price spikes. #### Share produced as a by-product About 95% of primary supply comes as a by-product of copper (Nassar, Graedel & Harper 2015, approximate). #### Who does it: global | Company | Country | Activity | Volume | Year | Source | |---|---|---|---|---|---| | **Chinese copper refiners (country total)** operator volumes not published; China made 53% of world output | China | selenium from anode slimes | 2,000 t Se (country refinery output) | 2025 | [USGS MCS 2026](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | | **Japanese copper refiners (country total)** operator volumes not published; Japan led world exports with 16.6% by value in 2024 (Comtrade) | Japan | selenium from anode slimes | 640 t Se (country refinery output) | 2025 | [USGS MCS 2026](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | | **Umicore (Hoboken)** not published | Belgium | precious-metal refining and selenium recovery | not published | 2025 | [USGS MCS 2026 (Belgium output 200 t)](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | | **KGHM Polska Miedz** not published separately; Poland's figure is reported and KGHM is the Polish copper refiner | Poland | copper refining with selenium recovery | not published | 2025 | [USGS MCS 2026 (Poland reported output 67 t)](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | | **Russian copper refiners (country total)** operator volumes not published | Russia | selenium from anode slimes | 320 t Se (country refinery output) | 2025 | [USGS MCS 2026](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | | **Canadian copper refiners (country total)** operator volumes not published | Canada | selenium from anode slimes | 130 t Se (country refinery output) | 2025 | [USGS MCS 2026](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | #### Who does it: India | Company | Country | Activity | Volume | Year | Source | |---|---|---|---|---|---| | **Hindalco Industries (Birla Copper, Dahej)** no later company figure published; USGS puts India's 2025 output at 90 t | India | copper smelting and refining; selenium from anode slimes of imported concentrate | 73.9 t Se | 2010-11 (latest company figure published) | [IBM Indian Minerals Yearbook 2020 (Selenium and Tellurium)](https://ibm.gov.in/writereaddata/files/11292021123510Selenium_Tellurium _2020.pdf) | | **Hindustan Copper (Ghatsila smelter, Jharkhand)** no selenium output since 2006-07 | India | selenium recovery plant with 14.6 t/yr capacity | 0 t Se | 2019-20 | [IBM Indian Minerals Yearbook 2020](https://ibm.gov.in/writereaddata/files/11292021123510Selenium_Tellurium _2020.pdf) | | **India (country total)** | India | refined selenium from copper slimes | 90 t Se (country refinery output; capacity 100 t) | 2025e | [USGS MCS 2026 (revised on company and government reports)](https://www.usgs.gov/centers/national-minerals-information-center/selenium-and-tellurium-statistics-and-information) | India refines about 90 t of selenium a year (USGS 2025e), almost all from copper anode slimes at Hindalco's Dahej complex, since Hindustan Copper has made none since 2006-07 and Vedanta's Tuticorin smelter has been shut since 2018. Demand is larger: India imported 575 t in 2019-20 (IBM) and took 13.8% of world selenium imports by value in 2024 (Comtrade). ## Other sections - [Summary](https://www.materialinsights.org/commodities/selenium/index.md) - [Overview](https://www.materialinsights.org/commodities/selenium/overview/index.md) - [Correlation](https://www.materialinsights.org/commodities/selenium/correlation/index.md) - [Production](https://www.materialinsights.org/commodities/selenium/production/index.md) - [Stocks](https://www.materialinsights.org/commodities/selenium/stocks/index.md) - [Cycles](https://www.materialinsights.org/commodities/selenium/cycles/index.md) - [Trading](https://www.materialinsights.org/commodities/selenium/trading/index.md) - [Movement](https://www.materialinsights.org/commodities/selenium/movement/index.md) - [Criticality](https://www.materialinsights.org/commodities/selenium/criticality/index.md) - [Characteristics](https://www.materialinsights.org/commodities/selenium/characteristics/index.md) - [Emissions](https://www.materialinsights.org/commodities/selenium/emissions/index.md) - [Relationships](https://www.materialinsights.org/commodities/selenium/links/index.md)