Overview
Cerium is more abundant in the crust than copper and lanthanum than lead, so their criticality is not geological — it is that 85–90% of rare-earth separation sits in China. Neither is mined alone: both come in fixed proportion with magnet-grade Nd and Pr and can be neither withheld nor scaled without moving NdPr output. Two streams already hold them outside the ore. Phosphogypsum, the waste of phosphate-fertilizer production at 4–6 t per tonne of P₂O₅, has accumulated to 3.7–6+ billion t with 200–300 Mt generated annually and only ~35% utilized; the rare earths transferred into it from the ore in full, and La and Ce make up to 60% of that concentrate. Spent FCC catalysts add ~400,000 t/year carrying ~3% La and Ce oxides, almost all landfilled. ARBOK recovers both in a single pass on the Arbok-SA route, in which the acid medium that dissolves the phosphogypsum is produced by the same process.
The loss loop nobody names. The FCC case is not a scarcity case, it is a double-payment case. Lanthanum stabilises the zeolite in fluid catalytic cracking catalyst — structure, catalyst life, conversion. Catalyst is replaced continuously, and the spent load, at ~3% La and Ce oxides, is landfilled. The refinery therefore pays for lanthanum in the fresh catalyst and pays again, weeks later, to bury the same lanthanum. Both payments are made by the same plant on the same site.
The 2011 precedent, and why it matters commercially. When China tightened rare earth quotas in 2011, lanthanum rose two orders of magnitude. Catalyst manufacturers imposed rare-earth surcharges and refiners moved to low- and zero-rare-earth formulations. The industry closed the problem not by finding lanthanum but by designing it out, paying for it in conversion and yield. The consequence persists: refiners today run less lanthanum than is technically optimal because they do not trust the supply — and still discard all of what they do use. This is the sales argument. The buyer has already been burned once and has already paid, in yield, for the workaround.
> Core route and measured product balance: Arbok-SA preprint, DOI 10.5281/zenodo.21360287 (no vault card yet). Gypsum purification: see ARBOK-PHOSPHOGYPSUM. Magnet-grade fraction of the same concentrate: see ARBOK-Scandium-REE.
Applications
Primary use cases: La and Ce recovery from phosphogypsum stacks and fresh phosphogypsum, and from spent FCC catalyst leachates.
Outputs/uses: cerium for auto catalysts and for polishing glass, screens and optics; lanthanum for FCC catalysts, optical glass and NiMH anodes; Nd and Pr from the same concentrate; acids and clean water as co-products.
Industries and users: phosphate and fertilizer producers, oil refineries, glass and optics manufacturers, catalyst makers.
Scale: modular; dissolution module 150–200 t/day, scaled by stack volume.
Operating Principle
One pass, not two operations. Ground phosphogypsum is dissolved in the process's own acid medium — no reagent is purchased — and the resulting stream is separated by Arbok cold boiling under deep vacuum at ambient temperature, 2–4 kWh/t of feed. The process employs no furnaces, catalysts, membranes or consumable reagents, and therefore emits no CO₂ from the recovery step and removes stack storage and its associated penalties. La, Ce, Nd and Pr are separated into individual oxides in the same pass, inside the solution itself, with only final polishing after it — the classical cascade of hundreds of stages, where the Chinese separation monopoly sits, is not required. Radionuclides report to an immobilized mass of 0.1–0.5% of volume. Spent-catalyst leachates enter the same tract.
Key Parameters
Process: deep vacuum, ambient temperature, 2–4 kWh/t; dissolution module 150–200 t/day; radionuclides 0.1–0.5% of volume; ~99.5% of mass leaves as commercial product.
Resource — phosphogypsum: 4–6 t per tonne of P₂O₅; 3.7–6+ billion t accumulated; 200–300 Mt/year generated; ~35% utilized. US holds ~1.5 billion t, ~1 billion t in 25 Florida stacks, growing ~30 Mt/year.
Resource — spent FCC catalyst: ~400,000 t/year worldwide, La and Ce oxides ~3% by mass, almost entirely landfilled.
Grade: REO ~0.3% in phosphogypsum, of which La and Ce up to 60% — approximately 1.8 kg of La+Ce per tonne.
Prices: lanthanum $3.18/kg (SMM, 3 August 2026) — range-bound at low absolute levels after an 18.3% move the prior month; cerium ~$4.36/kg; FCC grade ~$2.67/kg. Lanthanum is 25–30% of world rare earth output by mass and is produced in fixed ratio with Nd and Pr regardless of its own demand. China: 60–70% of lanthanum output and 85–90% of world separation. Lanthanum is on the EU critical raw materials list.
Architecture and Components
Dissolution reactors in the process's own acid medium; vacuum cold-boiling separation train; radionuclide immobilization mode; in-solution separation into individual oxides; final polishing; acid and water product lines. Modular, integrable into existing phosphate-processing plants.
Advantages
Technical: dissolution and separation in a single operation; no external reagent, no furnace, no membranes; handles both phosphogypsum and catalyst leachates on the same tract.
Economic: the La and Ce line alone (~1.8 kg/t, ~$7 at $3–4/kg) would never justify standalone mining; the acids and clean water produced in the same pass are high-margin products that carry the process, so La and Ce are recovered at no separate operating cost. Spent FCC catalyst is stronger on its own: ~30 kg/t → ~$105 where landfill is paid today.
Environmental: no CO₂ from the recovery step; radionuclides immobilized; phosphogypsum stacks eliminated rather than monitored.
Strategic: supplies La and Ce outside the Chinese separation monopoly to refineries, glassmakers and catalyst producers — the US annual phosphogypsum increment alone carries 54,000 t/year, many times domestic consumption.
Integrations
Integrates into existing phosphate-processing sites alongside the Arbok-SA route and ARBOK-PHOSPHOGYPSUM; the Nd/Pr fraction of the same concentrate is covered by ARBOK-Scandium-REE; oil-refinery tie-in for spent FCC catalyst leachates.
Deployment & Operation
Steps: phosphogypsum and catalyst-leachate characterization → module sizing → install at the phosphate-processing site or legacy stack → commissioning. Continuous, ambient conditions, modular scaling by volume.
TRL
TRL 9. Built on the Arbok-SA route, with the measured product balance from separation of industrial phosphate-plant effluent documented in the Arbok-SA preprint (DOI 10.5281/zenodo.21360287); the rare-earth concentrate is taken from the same pass.
Market Potential
La and Ce are cheap but structurally captive: 85–90% of separation capacity is Chinese, and because both are locked in fixed ratio to NdPr, neither price nor demand can call forth additional supply. Every FCC unit, glass line and polishing plant outside China therefore depends on a separation step it does not control. The world phosphogypsum flow carries ~450,000 t of La and Ce per year and spent FCC catalysts a further ~12,000 t — the objective is not to flood a market but to give refineries and glassmakers domestic feedstock.
Typical Project Economics
Per tonne of phosphogypsum: ~1.8 kg La+Ce (~$7 at $3–4/kg) plus Nd and Pr from the same concentrate — recovered at no separate operating cost, because the acids and clean water from the same pass carry the process. Per tonne of spent FCC catalyst: ~30 kg La+Ce, ~$105, against a disposal cost today. Per refinery: a plant withdraws 2,000–5,000 t of catalyst a year, so 60–150 t of La+Ce = $210,000–525,000, plus $200,000–1,500,000 of disposal at $100–300/t that stops being spent, plus the nickel and vanadium deposited on the catalyst from the feed as a further line. Total $0.4–2 M a year per refinery — the strongest single-site case in this file, and the one that needs no phosphate plant. US annual increment: 54,000 t of La and Ce, ~$0.2B/year; accumulated US stock 2.7 Mt, ~$10B.
Risk Factors
Low unit price (3–4 $/kg) means the case depends on co-product economics rather than on the rare earths alone; REO grade and La/Ce split vary by phosphate source and must be assayed per site; purity per pass on adjacent pairs must be stated per project and is commercial information; radionuclide-residue acceptance; conservative phosphate-industry adoption.
Related Technologies
ARBOK-PHOSPHOGYPSUM · ARBOK-Phosphate · ARBOK-Scandium-REE · ARBOK Critical-Materials Recovery