The recovery of the lanthanides from phosphate rock

Phosphate rock contains up to 1% lanthanide (rare earths) oxides present in isomorphous substitution for Ca2+. Lanthanum, cerium and neodymium form about 80% of the total. When the rock is leached with H2SO4 the lanthanides are mostly (about 70%) lost in the gypsum residue. When the rock is leached with HNO3 or HC1, more than 80% can be recovered without interference with fertiliser production. At an annual production of 130 million tons, phosphate rock represents an important source of lanthanides. The different methods of recovery are reviewed.