Byproduct Recovery

Rare earth byproduct recovery takes rare earths from material mined or processed mainly for something else, such as phosphate fertilizer waste, alumina refinery residue, uranium-ore residue, iron ore streams, coal ash and mine tailings. The material has already been mined. In 2017 the U.S. Geological Survey listed an open question: whether rare earths in ores that host another primary commodity can be developed as a byproduct (USGS Professional Paper 1802-O).

For scandium, byproduct recovery is already the whole supply. The USGS says it was produced exclusively as a byproduct in 2025, primarily from nickel and titanium process streams and previously processed tailings and residues, and that its resources rarely occur in high concentrations (USGS Mineral Commodity Summaries 2026).

Where rare earth byproduct recovery feedstock comes from

• Phosphate. A 2023 review, co-written by a Tianqi Lithium researcher, says more than 70% of the rare earths in phosphate rock end up in phosphogypsum during sulfuric acid digestion (Xie et al., Molecules, 2023). See phosphogypsum.
• Bauxite residue. Rare earths in bauxite end up in red mud at about twice their original concentration, a 2017 University of Toronto study notes, citing earlier work; Rio Tinto supplied the study's residue samples and technical support (Reid et al., Scientific Reports, 2017). See bauxite residue.
• Iron ore. In 2017 the USGS said some magnetite-hematite iron deposits, such as Pea Ridge in Missouri, could yield rare earths as a byproduct of iron mining, and described China's largest rare earth mine, Bayan Obo, as producing iron ore as well as bastnaesite and monazite (USGS, 2017).
• Uranium. In Kazakhstan, SARECO built a plant at Stepnogorsk to recover rare earths from uranium-ore residue (Sumitomo, November 2012). See polymetallic / other.
• Coal ash. A 2016 study found U.S. fly ash from Appalachian coal averaged 591 mg/kg of total rare earths (Taggart et al., Environmental Science & Technology, 2016).
• Tailings. A 2025 review by Finland's VTT says rare earth beneficiation plants have yields of 36 to 78%, leaving a significant amount in tailings (Hajdu-Rahkama and Kinnunen, 2025).

Why grade and chemistry make byproduct recovery hard

In phosphogypsum, the rare earths are mainly locked inside gypsum crystals, which keeps leaching efficiency low. Contents vary widely by region, some below 0.01 weight percent, and the impurities include radioactive uranium-235, radium-226 and thorium-232 (Xie et al.).

The main rare earths in the 2017 Toronto bauxite residue sample totaled about 0.03 weight percent (Reid et al.). Leaching it directly with acid forms silica gel, and iron dissolves along with the target metals, a 2018 study with co-authors from the German process firm MEAB Chemie Technik says (Alkan et al., Scientific Reports, 2018).

In the 2016 coal ash study, heated nitric acid recovered about 70% of the rare earths in Powder River Basin ash, and the authors concluded that recovery depends on extraction methods tailored to the feed coal (Taggart et al.).

Byproduct recovery operations and pilots

• LKAB, Sweden. LKAB, wholly owned by the Swedish state (LKAB), says the waste stream from its iron ore pellet production contains apatite, which holds all 17 rare earth elements (LKAB, February 2026). Sweden's Land and Environmental Court granted a permit for its planned critical minerals park in Luleå in May 2026, and LKAB says investment decisions will rest on several parameters (LKAB, May 26, 2026). On September 29, 2026, it said its demonstration plant was due to begin operating soon (LKAB).
• Sumitomo Metal Mining, Philippines and Japan. In April 2016, SMM said its Philippine subsidiary Taganito HPAL Nickel Corporation would make a scandium intermediate for processing into scandium oxide at its Harima Refinery, with production planned from spring 2018 (SMM, April 2016). Separately, the USGS reported that scandium materials produced in the Philippines were sent to Japan for processing into oxide in 2025, without naming the producer or plant (USGS).
• Rio Tinto, Quebec. Rio Tinto extracts high-purity scandium oxide from the waste streams of titanium dioxide production at Sorel-Tracy (Rio Tinto, May 2022), where its demonstration plant began production in 2022. In November 2025, it said a Canada Growth Fund investment would raise a facility under construction to a nameplate capacity of nine metric tons a year (Rio Tinto, November 2025).
• SARECO, Kazakhstan. Kazatomprom (51%) and Sumitomo Corporation (49%) set up SARECO and opened its Stepnogorsk plant in November 2012 (Sumitomo, November 2012). In September 2026, Lindian Resources said it had acquired full ownership of the plant and plans to feed it monazite concentrate from its Kangankunde mine in Malawi (Lindian annual report, September 2026). Lindian targets first processing at SARECO in the fourth quarter of 2026 (Lindian, August 10, 2026), which REEx noted was still a target (REEx, August 2026).
• Mosaic and Rainbow Rare Earths, Brazil. In March 2026, Mosaic Fertilizantes P&K and Rainbow Rare Earths entered a joint project development agreement for a plant at Uberaba, Minas Gerais, to treat about 2.7 million metric tons of phosphogypsum a year. Initial production is targeted for 2030, subject to further studies, regulatory approvals, financing arrangements and investment decisions (Mosaic). REEx called the economics promising but far from bankable (REEx, March 2026).
• U.S. coal pilots. On July 1, 2026, the Department of Energy selected five projects that use coal and coal-based feedstocks to produce rare earths and other critical materials at pilot-scale facilities on their industrial sites, including Peabody Energy and CONSOL Innovations. DOE said selection for award negotiations is not a commitment to issue an award (DOE, July 2026).

On LKAB's permit, REEx wrote that "an environmental permit is not industrial independence" (REEx, May 2026). In June 2026 it reported that ElementUSA, which aims to recover minerals from bauxite residue at a Louisiana alumina refinery, had not yet demonstrated sustained commercial-scale production (REEx, June 2026).

Frequently asked questions