Process mineralogy studies of Corrego do Garimpo REE ore, Catalao-I alkaline complex, Goias, Brazil

Abstract Corrego do Garimpo is described as a lateritic rare earths (REE) deposit related to hydrothermal alteration of dolomitic carbonatitic rocks. Although the deposit has been known since the sixties, all the previous mineral dressing attempts to concentrate the REE bearing minerals resulted in unsatisfactory outcomes. Process mineralogy studies of bulk and borehole samples were fundamental to understanding the ore's behavior and to the development of an unusual physical concentration process. The ore comprises a medium to very fine-grained soil material with large amounts of secondary (autigenous) minerals. Monazite, the essential REE bearing mineral, occurs as microcrystalline aggregates, sometimes presenting colloidal textures, which are frequently associated with iron oxide—hydroxides and quartz. Since these aggregates are extremely friable, the monazite crystallites are mainly associated with the −20 μm size fraction. These particular characteristics supported the development of an unconventional mineral processing method for monazite based on disaggregation, followed by scrubbing and hydrocyclone classification operations. Three volumetric samples and 27 borehole samples, comprising four ore types, have been studied. The attained final products, −10 μm, were further submitted to leaching tests, simulating chemical processing for the REE sulphuric extraction at low temperature.