Investigations on mineralogical characteristics of rare earth minerals in Bayan Obo tailings during the roasting process

This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal, Ca(OH)(2) and NaOH. Roasting experiments and leaching experiments were carried out to study the decomposition of rare earth minerals. The results indicated that bastnaesite and monazite could be completely decomposed at 650 degrees C and the leaching ratio of rare earths could reach 89.78%. The reaction mechanisms of bastnaesite and monazite at 650 degrees C were analyzed. For bastnaesite, both the outer layer decomposition and inner core decomposition occurred simultaneously during the roasting. However, monazite was decomposed in a spatial sequence starting from the outer layer and proceeding to the inner core.