Yields of rare earths in the process of smelting steels by magnesia crucible

Abstract

Abstract. Two types of steels containing rare earths (RE) were smelted by the vacuum induction furnace with magnesia crucible, RE metals were added in liquid steel at the end of the smelting process, chemical compositions of the test steels were analyzed, and inclusions were observed by scanning electron microscope with energy dispersive spectrometer. The experimental results show that the yields of RE have no direct relationship with the oxygen and sulphur contents, but decrease with the increasing of RE addition amounts. The reaction between RE and MgO (the material of the crucible) is the major RE consumption mode, parts of the outer refractory are peeled off and become inclusions in the test steels. Because of the excessively active chemical properties, rare earths trend to react with refractory materials and metallurgical slag. Therefore, it is very difficult to utilize RE in the industrial production processes with con-casting, adding RE in the non-slag and non-refractory special processes may be feasible.