The Bureau of Mines has devised a process for the in-plant recovery of about 90% of the chromium and molybdenum and well over 90% of the nickel and iron from stainless steelmaking electric-furance dusts, argon-oxygen decarburization vessel dusts, mill scale, and oily swarf. Other metals such as manganese are also recovered. A key to the process is the blending of the mixed wastes with coke breeze reductant and binder and pelletizing the mixture with a drum or disk pelletizer. The mill scale and coke breeze are sized to minus 35 mesh. The other ingredients are fine and require no sizing. Small amounts of cement or bentonite can serve as binder. Such pellets, after drying, have sufficient strength for handling and adding to the furnace for metal recovery. Some silicon or aluminum furnace addition helps reduce chromium from the slag. The pellets can be smelted in all-pellet heats, but the recommended procedure is to charge the pellets to the production furnace in amounts up to 20% of the charge, or in proportion consistent with the waste generation rate, in lieu of part of the scrap normally charged. The techniue is applicable to a variety of stainless steelmaking or related specialty steelmaking wastes.
Paper 4th Int. Symp. on Agglomeration, Chelsea, MI, 1985, PP. 421- 431