LAUSR

Abstract Cerium, the most abundant rare earth element (REE), is typically the largest component of the hard rock REE ores. Demand for less prevalent REE, such as neodymium and dysprosium, have led to a market saturation and price collapse of cerium. One method of improving the economics of REE processing operations is to effectively remove cerium from the solution prior to SX. This is accomplished by the oxidation of Ce (III) to Ce (IV), which precipitates as cerium hydroxides. This study probes the efficacy of four oxidants for oxidative cerium precipitation from chloride solutions: hydrogen peroxide, sodium hypochlorite, potassium permanganate, and Caro's Acid. Cerium oxidation was tested using these oxidants at varying stoichiometry, a pH range of 1.0 to 4.0, temperatures of 25, 45, and 65 °C, and varying cerium concentrations. Kinetic constants were calculated from time sampled data. Complete cerium removal is achievable using potassium permanganate and Caro's acid in the absence of other REE. Thermodynamic data was used to create theoretical speciation and pourbaix plots illustrating the conditions in which cerium was oxidized using these reagents.