Production of lanthanon and thorium compounds from monazite. II

A partly cyclic process is described for the separation of the mixed hydroxides of the cerium‐group elements into cerous salts and into concentrates containing, respectively, lanthanum salts, mixed praseodymium‐neodymium‐samarium hydroxides or nitrates, and crude thorium phosphate. The mixed hydroxides of praseodymium, neodymium and samarium are fractionally precipitated with ammonium hydroxide, leaving lanthanum in solution. Portion of the praseodymium, neodymium and samarium concentrate is used to precipitate basic salts of ceric cerium and thorium, the remainder being recovered. Cerium is obtained from the mixture of basic salts by reducing ceric compounds to the cerous state and precipitating thorium as a basic salt. Lanthanum is finally precipitated as lanthanum oxalate or lanthanum carbonate and cerium as sodium cerium sulphate. Electrometric titrations of lanthanon solutions have been made at 80° to obtain data facilitating control of the various separations.