Molybdenum Tools
Ferromolybdenum Addition Calculator
Work out how much ferromolybdenum (FeMo) to charge into a steel heat to reach your target molybdenum content. Enter the heat weight, the molybdenum percentages, the FeMo grade, and your expected recovery to get the addition in kilograms and per tonne of steel.
Recovery is typically 92-98% for ladle/tapping additions and 80-85% for converter additions. Use your own plant data where available.
Contained Mo needed
300.0 kg
Ferromolybdenum to add
485.8 kg
Addition rate
4.86 kg/t
Formula used
FeMo (kg) = (Steel weight kg × (Target Mo% − Initial Mo%) ÷ 100) ÷ (Grade Mo% ÷ 100 × Recovery% ÷ 100)
Worked example
A 100-tonne heat needs its molybdenum raised by 0.3%, using FeMo 65. The contained molybdenum required is 100,000 kg × 0.3% = 300 kg. Dividing by the grade (0.65) gives about 461 kg of ferromolybdenum at full recovery; at 95% recovery you would charge about 486 kg.
Recovery depends heavily on where and how the alloy is added. Ladle additions during tapping with good deoxidation and basic slag recover 92-98% of the molybdenum, while converter additions lose more to slag and typically recover 80-85%.
Recovery guidance
| Addition method | Typical Mo recovery |
|---|---|
| Ladle / during tapping | 92-98% |
| Converter | 80-85% |
Values are typical industry ranges for planning. Actual recovery varies with slag chemistry, temperature, deoxidation practice, and dissolution time.
Frequently asked questions
How do you calculate how much ferromolybdenum to add to steel?
Use the mass balance: FeMo (kg) = (steel weight in kg x (target Mo% - initial Mo%) / 100) / (FeMo grade Mo% / 100 x recovery% / 100). The first part is the contained molybdenum you need; dividing by grade and recovery converts it into kilograms of ferromolybdenum alloy to charge.
What is the molybdenum recovery rate for ferromolybdenum?
Recovery is typically 92-98% when ferromolybdenum is added to the ladle during tapping, and around 80-85% when added to the converter, because oxidation losses to slag are higher. Always use your own plant data where it is available.
How much ferromolybdenum is needed for a 100-tonne heat at 0.3% Mo?
For a 100-tonne (100,000 kg) heat with a 0.3% Mo increase using 65% FeMo at full recovery, you need about 300 kg of contained Mo, which is roughly 461 kg of ferromolybdenum. At 95% recovery this rises to about 486 kg.
What grades of ferromolybdenum are common?
Commercial ferromolybdenum is usually supplied as FeMo 60, FeMo 65, or FeMo 70, where the number is the approximate molybdenum content in percent. Higher-grade material contains more contained molybdenum per kilogram of alloy.
Need ferromolybdenum?
Centura Worldwide supplies FeMo 60/65/70 with mill test certificates, sourced from Canada and North America. Tell us your grade and tonnage for pricing and lead time.