Abstract: A method is provided for treating molybdenum concentrates in a roasting furnace having a first roasting zone and at least a second roasting zone, the concentrate containing residual flotation oil in an amount over 2% by weight which during roasting inhibits the roasting capacity of the furnace. The improvement resides in deoiling the molybdenite concentrate, feeding the deoiled concentrate to the first roasting zone, and applying heat to the concentrate in the first roasting zone, including the sensible heat of the concentrate and heat generated by extraneous fuel, sufficient to heat the concentrate to a roasting temperature sufficiently high to initiate a substantially self-sustaining roasting reaction but not exceeding about 1250.degree. F. The amount of heat generated by combustion of the extraneous fuel is not substantially in excess of that required to heat the concentrate to the temperature at which self-sustaining roasting reactions are initiated in the first roasting zone.