Meltstock molybdenum products
Meltstock molybdenum products are used extensively to produce various metal alloys. The table shows which meltstock products are typically used for each type of alloy.
Stainless steel, carbon steel, tool steel, and high-speed steel are typically melted in an electric arc furnace. The initial charge usually contains alloy steel scrap, pig iron, and a source of "Mo units" to attain the proper composition.
Using scrap ensures that recycling provides an important share of the melt. Recycled material comes from in-house scrap, scrap collected from steel fabricators, and remelt stock purchased from recyclers. Depending on the steel grade and market factors, the molybdenum from recycled material can cover up to the full need. When virgin molybdenum is needed it is usually added as technical molybdenum oxide with the scrap charge to approach the specified molybdenum content. If only small amounts of new molybdenum are required, the final chemistry is typically reached through ferromolybdenum (FeMo) addition. After meltdown, the liquid metal is usually transferred into an AOD (Argon Oxygen Decarburization) vessel or a ladle furnace for further metallurgical treatment. Ferromolybdenum is added at this stage to adjust the composition to the specified Mo content.
FeMo is used exclusively as the source of molybdenum in cast iron. Superalloys, on the other hand, use only molybdenum pellets because of the alloys' requirement for high purity additions and vacuum melting.
Molybdenum metal scrap generated by mill product manufacturers is also used for alloy additions. The balance between molybdenum metal and other molybdenum sources depends upon the relative economics and availability of the various sources of molybdenum units.
Roasted molybdenite concentrate (technical Mo oxide)
Technical molybdenum oxide is the principal product for adding molybdenum to carbon and stainless steels. It typically contains 56-58% Mo and a maximum of 0.5% Cu, and is available in the following forms and packaging options:
- Powder (max 400 mesh) packaged in:
- Cans with 10 kg or 20 lbs Mo content
- Steel drums (250 kg or 500 lbs)
- Bulk bags ( 1000 kg or 1500 kg)
- Pillow shaped briquettes
- Packaged in steel drums (250 kg or 500 lbs)
- Bulk bags (1000 kg or 1500 kg)
Product standards include:
- ASTM A146-04 Standard Specification for Molybdenum Oxide Products
Roasted molybdenum concentrate (Technical Mo oxide) powder (left) and briquettes
(Courtesy of Molymet, Chile)