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

摘要

A study was carried out to recover RE and Mnfrom the rare earth mud of western Sichuang in China, whichcontains about 3-7 percent RE and 2-10 percent Mn. The RE ofthe mud exists in amorphous Mn-Fe oxide. It is necessary todestroy the Mn-Fe amorphous structure to recover the RE fromthe mud. A 3.6-g/l Na_2SO_3 solution was first used to leachMn at room temperature. About 90 percent Mn was leached andthe Mn-Fe amorphous structure was destroyed. The leachingsolution is further treated with KMnO_4 to remove impurities.A MnCO_3 product with purity of 90.5 percent can be obtained.At the same time, the removed Mn mud is further roasted withNH_4Cl at about 450 deg C and then directly leached by water.The recovery of RE can reach to 73.4 percent, which is higherabout 20 percent than that of the mud being directly roasted. Thepurified leaching solution is precipitated by NH_4HCO_3 andan easy filtered crystal RE_2(CO_3)_3 is obtained. Based on thestudy, a flow sheet of separation and recovery of RE and Mnfrom MN rare earth mud was proposed.