Patent ID: 8628734

Claim:
A method for recovering rare earths from lamp waste A which contains a plurality of fluorescent materials which comprises halophosphates and rare earth fluorescent material, wherein the method comprises the following sequence of method steps: a) a mechanical treatment step, wherein the lamp waste A is treated to remove coarse constituents A′ to leave a solid starting material A″ which comprises rare earth containing fluorescent material; b) an extraction step to extract halophosphates, wherein the solid starting material A″ undergoes a cold acid leaching to produce a liquid filtrate B′ and a solid residue B″, wherein B′ contains waste material comprising halophosphates and B″ comprises rare earth compounds; c) an extraction step to extract rare earth compounds, yet insoluble in step b), yet readily soluble in acids, wherein the residue B″ undergoes a hot acid leaching to produce a liquid filtrate C′ and a solid residue C″, wherein C′ contains rare earth compounds readily soluble in acids and solid residue C″ contains as yet insoluble rare earth compounds; d) a digestion step by way of alkaline digestion to digest compounds containing rare earth material, yet insoluble in step c), wherein the solid residue C″ is digested and extracted with hot water or acid to produce a liquid filtrate D′ containing rare earth compounds and solid waste residue D″; e) a final treatment step to precipitate rare earth material wherein the liquid filtrates C′ and D′ are each treated to recover the rare earths as precipitates.