As part of its mission to assure the maximum recovery and use of the nation's mineral resources, the Bureau of Mines investigated an improved procedure for producing rare earth-silicon alloys. For example, a charge consisting of 681 grams of mixed rare-earth oxides, 309 grams of ferrosilicon (75 wt-pct si), and 182 grams of aluminum metal along with a flux consisting of 681 grams of cao and 45 grams of mgo was reacted at 1,500 deg c in an induction furnace. Good slag-metal separation was achieved. The alloy product contained, in weight-percent, 53 rare earth (re), 28 si, 11 fe, and 4 al with a rare earth recovery of 80 pct. In current industrial practice, rare earth recoveries are usually about 60 pct in alloy products that contain approximately 30 wt-pct each of rare earths and silicon. Metallurgical evaluations showed that the alloys prepared in this investigation to be as effective in controlling the detrimental effect of sulfur in steel and cast iron as the commercial rare earth-silicon-iron alloys presently used in the steel industry.
Pub. in the Rare Earths in Modern Science & Technology, V. 3., Aug. 30, 1982, PP. 557-560