Abstract
The sulfuric acid bake followed by water leaching is now well-established technology used for processing of ores and concentrates containing rare earth phosphate mineralization. Gangue minerals can have a significant impact on the process. In this work, we tease out the impact of the presence of iron minerals on the monazite acid bake process, focusing particularly on magnetite. Sulfuric acid baking and leaching of a magnetite sample alone and a magnetite/monazite mixture at bake temperatures ranging between 200 and 800 °C was conducted. The presence of magnetite with monazite had a significant impact on the extraction of rare earth elements and impurities from monazite and these were explained by the phases formed in the bake.