The invention discloses a method for preparing high-purity
terbium oxide, belonging to the technical field of rare-earth separation. The method comprises the following steps of feeding mixed rare-earth
oxide,
hydrochloric acid and pure water into a container with a stirring device and a heating device, stirring, and filtering so as to obtain a mixed rare-earth
chloride solution; adding the mixed rare-earth
chloride into another container with a stirring device, and continuously stirring so as to obtain a separated material; by taking the separated material as a
raw material, continuously extracting and separating by using a first extraction agent, a caustic soda liquid and a returning fluid so as to obtain a rich
terbium chloride solution; by taking the rich
terbium chloride solution as another
raw material, adding a second extraction agent and the returning fluid, further extracting and separating so as to obtain a high-purity
terbium chloride solution; introducing the high-purity
terbium chloride solution into a
settling pond, and filtering so as to obtain
solid oxalate terbium; and introducing the
solid oxalate terbium into a roller table type
tunnel kiln for firing, controlling the firing temperature and the firing time, discharging from the roller table type
tunnel kiln so as to obtain high-purity terbium
oxide, wherein the purity of the terbium oxide is 99.9%. The first-pass yield is high, and the preparation cost is low.