Recovery of Valuable Metals from Acoustic Magnet Swarf Slurry

Acoustic magnet swarf slurry (AMSS) has 1900 tons production worldwide. The composition of AMSS contained 12.45% neodymium, 34.35% iron, 0.48% boron and 52.5% of cooling reagent. Removing cooling reagent and decreasing iron dissolution percent were achieved by oxidation roasting and selective leaching. Selective leaching removed 89% of iron with parameter of 0.5M HCl, solid-liquid ratio equal to 1:100, 4 hours at 95℃. The rest of iron was separated by solvent extraction with Aliquat 336 as extractant. The optimal parameters of extracting iron were 0.1M A336, 3M chloride ion, aqueous-organic ratio equal to 1:3 and mixed for 1 minute. Oxalic acid added to solution after solvent extraction to precipitate neodymium. The final product was neodymium oxidize with 99% of purity by calcined neodymium oxalate at 900℃ for 0.5 hour. The recovery percent of neodymium was 99%.