Ferromanganese (Fe-Mn) is a metallic ferroalloy usually added with ferrosilicon as a ladle additive in the manufacture of steel. It is a ferroalloy composed mainly of manganese and iron, and usually contains much lower levels of minor elements such as carbon, phosphorus and sulphur. Fe-Mn is an important additive used in steel production as a deoxidiser. It is a master alloy of iron and manganese with a manganese content of at least 65% and at most 95%.

Fe- Mn is a ferroalloy with a high manganese content. It is produced by heating a mixture of manganese (MnO2) and iron (Fe2O3) oxides with carbon usually in the form of coal and coke, either in a blast furnace or in an SAF. The oxides are carbothermally reduced to produce Fe-Mn. It is produced in three types namely (i) standard high carbon Fe-Mn, (ii) medium carbon Fe-Mn and (iii) low carbon Fe-Mn. High carbon Fe-Mn has a manganese content of 72% to 82%, a carbon content of 6% to 8% and a silicon content of about 1.5%. Medium carbon Fe-Mn has a manganese content of 74% to 82%, a carbon content of 1% to 3% and a silicon content of about 1.5%. Low carbon Fe-Mn has a manganese content of 80% to 85%, a carbon content of 0.1% to 0.7% and a silicon content of 1% to 2%.

Manganese plays an important role in the production of steel as a deoxidiser, desulphuriser and alloying agent. It is a milder deoxidiser than silicon but increases the effectiveness of silicon by forming stable manganese silicates and aluminates. It is used as an alloying element in almost all types of steel. Of particular interest is its modifying effect on the iron-carbon system by increasing the hardenability of the steel. Adding manganese as medium carbon Fe-Mn or low carbon Fe-Mn instead of high carbon Fe-Mn will add about 80% to 93% less carbon to the steel. Medium carbon nitrided Fe-Mn contains at least 4% nitrogen.

Fe-Mn is produced in various grades and sizes and is consumed in bulk form primarily in steelmaking as a source of manganese, although some Fe-Mn is also used as an alloying agent in the production of iron castings. Manganese, intentionally present in almost all steels, is used as a steel desulphuriser and deoxidiser. It improves tensile strength, workability, toughness, hardness and abrasion resistance. By removing sulphur from steel, manganese prevents the steel from becoming brittle during hot rolling.