Technical Molybdic Oxide: Molybdenite Roasted in Nichols-Herreshoff Furnaces (US Bureau of Mines 1957)

Molybdenite concentrate is roasted in air in a multiple-hearth furnace: it dries on the top hearth at 300 °F and roasts on the lower hearths at up to 1,250 °F, coming out about 4 hours later as molybdic oxide. Result: technical molybdic oxide with 0.06 to 0.30 % sulphur, packed in cans or bags for the steel industry. Source: US Bureau of Mines Information Circular 7784, Molybdenum - A Materials Survey (1957), p. 37, practice of Molybdenum Corporation of America at Washington, Pa. Not given: feed rate, air, fuel, yield. The sulphur leaves as sulphur dioxide, a poisonous gas. Picture drawn by Youblob.