The raw material for smelting ferromolybdenum is mainly molybdenite (MoS2). Prior to smelting, the molybdenum concentrate is usually oxidised and roasted in a multi-pod furnace to produce roasted molybdenum ore with a sulphur content of less than 0.07%.
The external furnace method is commonly used in smelting ferromolybdenum. The furnace is a cylinder on a sand base lined with clay bricks, and ferrosilicon containing 75% silicon and a small amount of aluminium particles is used as the reducing agent.
After the charge is added to the furnace barrel at one time, it is smelted by top ignition. An initiator (saltpeter, aluminium or magnesium chips) is applied to the surface of the material. After calcination, it reacts violently, then calms down, releases slag and is removed from the furnace. The ferromolybdenum ingots are first cooled in a nest of sand and then sent to a cold room where they are washed with water for cooling, crushing and finishing.