Recovery of scandium, yttrium and lanthanides from zircon sand

Abstract

This is a process for extracting scandium from zircon ore. It utilizes feeding zircon sand to a fluidized bed chlorinator at about 1000.degree. C. to produce a vaporous (principally zirconium and silicon chlorides) phase and a solid residue and recovering scandium from the solid residue. Surprisingly, despite the relatively low sublimation temperature of scandium chloride the very low level of scandium present in zircon ore is concentrated in the residue (rather than going with the vapor phase, where it would not be concentrated), making recovery of scandium from the zircon ore economically feasible. Generally, the process can be part of the production of zirconium metal, whereby scandium is a byproduct of zirconium production. Preferably, the recovery is performed by leaching the residue with aqueous acid (e.g. HCl) to produce a scandium-containing aqueous solution, followed by contacting the aqueous solution with a polyalkyl phosphate-containing organic phase, the polyalkyl phosphate (e.g. tributyl phosphate) extracting scandium into the organic phase, followed by scandium precipitation by an ammonium addition to produce a scandium hydroxide precipitate and the scandium hydroxide is calcined, whereby scandium is recovered as an oxide. The residue generally also contains yttrium and lanthanides, and the yttrium and lanthanides can also be recovered from the residue as a part of the scandium recovery process. The recovering of the scandium chloride from the residue can also be performed by leaching the residue with alcohol (preferably methanol) to produce a scandium-containing alcohol solution (the remaining residue can then be recycled to the chlorinator). The leaching with alcohol can be followed by contacting the alcohol solution with oxalic acid to precipitate oxalates of scandium, thorium, and lanthanides.

Dependencies are inferred from the claim text.