Separation and recovery of RE and Mn from MN rare earth mud in China

Abstract A study was carried out to recover RE and Mn from the rare earth mud of western Sichuang in China, which contains about 3–7% RE and 2–10% Mn. The RE of the mud exists in amorphous Mn–Fe oxide. It is necessary to destroy the Mn–Fe amorphous structure to recover the RE from the mud. A 3.6-g/l Na 2 SO 3 solution was first used to leach Mn at room temperature. About 90% Mn was leached and the Mn–Fe amorphous structure was destroyed. The leaching solution is further treated with KMnO 4 to remove impurities. A MnCO 3 product with purity of 90.5% can be obtained. At the same time, the removed Mn mud is further roasted with NH 4 Cl at about 450°C, and then directly leached by water. The recovery of RE can reach to 73.4%, which is higher about 20% than that of the mud being directly roasted. The purified leaching solution is precipitated by NH 4 HCO 3 and an easy filtered crystal RE 2 (CO 3 ) 3 is obtained. Based on the study, a flow sheet of separation and recovery of RE and Mn from MN rare earth mud was proposed.