Ferro molybdenum

Overview

Ferromolybdenum (FeMo) is an alloy of iron and molybdenum containing between 60% and 75% molybdenum, the balance being essentially iron.¹ Together with technical molybdenum oxide and molybdenum metal pellets, it is one of the "meltstock" products used to add molybdenum to iron, steel and other alloys.²

It is a special ferroalloy, made in much smaller volumes than bulk alloys such as ferrochrome or ferromanganese.³ Ferromolybdenum is not itself listed as critical; its parent element has few substitutes in its main use, steel and cast iron.⁴

How it is made

Production starts with molybdenite (molybdenum sulfide) concentrate, which is roasted in air at 500–650 °C to give technical molybdic oxide containing at least 57% molybdenum and less than 0.1% sulfur.¹ Roasting takes place in multiple-hearth furnaces; the sulfur dioxide released is usually converted to sulfuric acid, and rhenium and selenium can be recovered from the off-gas.³ About 30–40% of technical oxide is converted into ferromolybdenum.¹

The oxide is then mixed with iron oxide or iron scrap and reduced metallothermically in refractory-lined crucibles. The EU reference document describes ferrosilicon as the preferred reductant, with a small amount of aluminum to balance the heat of reaction, and alloy blocks of 2.5–4 t.³ IMOA describes the reaction as an aluminum thermite reduction producing ingots of several hundred kilograms.¹ In both accounts the cooled alloy is broken, crushed and screened to the sizes buyers specify.³¹

Molybdenum mining is concentrated: China, Chile, the United States, Peru and Mexico accounted for 90% of mine output in 2025. Outside China and the United States, molybdenum is recovered only as a by-product of copper mining.⁴ Three US roasting plants convert concentrate to molybdic oxide, from which products such as ferromolybdenum are made.⁴

What it is used for

Most molybdenum ends up in iron and steel. In 2022, about 25% of newly mined molybdenum went into molybdenum-grade stainless steel and a further 54% into constructional steel, tool and high-speed steel, and cast iron. The remaining 21% went into upgraded products such as nickel alloys, chemicals, lubricant-grade molybdenum disulfide and molybdenum metal.⁵

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Grades and forms

Ferromolybdenum is sold crushed and screened in a wide range of sizes.³ Steelmakers can also add molybdenum as technical oxide, the material from which ferromolybdenum is made.²¹

Trade and policy

In 2021–24, US imports of ferromolybdenum came from Chile (74%), the Republic of Korea (21%) and the United Kingdom (4%). The US normal-trade-relations tariff on ferromolybdenum was 4.5% ad valorem at the end of 2025. China imposed export controls on molybdenum powders in February 2025, prompting the United States and other countries to look for alternative sources.⁴

The EU's definitive ferroalloy safeguard of November 2025 covers manganese and silicon alloys and does not include ferromolybdenum (CN 7202 70).⁶

This section is factual background, not legal or trade-compliance advice.

Recycling and substitution

Molybdenum is not separately refined from scrap, but it is reused as a component of recycled steel, superalloy and catalyst scrap; this may account for as much as 30% of US apparent supply. Boron, chromium, niobium and vanadium are potential substitutes in alloy steels, and tungsten in tool steels, although there is little substitution in practice.⁴

Sources

1. Molybdenum processing. International Molybdenum Association, accessed 2026-10-03. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

2. Molybdenum products. International Molybdenum Association, accessed 2026-10-03. ↩ ↩²

3. Best Available Techniques (BAT) Reference Document for the Non-Ferrous Metals Industries. European Commission, Joint Research Centre, accessed 2026-10-03. ↩ ↩² ↩³ ↩⁴ ↩⁵

4. Mineral Commodity Summaries 2026: Molybdenum. U.S. Geological Survey, accessed 2026-10-03. ↩ ↩² ↩³ ↩⁴ ↩⁵

5. Uses of new molybdenum. International Molybdenum Association, accessed 2026-10-03. ↩

6. Commission Implementing Regulation (EU) 2025/2351 imposing a definitive safeguard measure on imports of certain ferro-alloying elements. EUR-Lex, accessed 2026-10-03. ↩