Ferromanganese, a ferroalloy

Ferroalloy

Ferroalloy refers to various alloys of iron with a high proportion of one or more other element, manganese or silicon for example. It is used in the production of steels and alloys as a raw material.The main ferroalloys are:*FeAl – ferroaluminum...

 with high content of manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, is made by heating a mixture of the oxides MnO₂

Manganese(IV) oxide

Manganese oxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO2 is for dry-cell batteries, such as the alkaline battery and the...

 and Fe₂O₃

Iron(III) oxide

Iron oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron oxide , which is rare, and iron oxide , which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main...

, with carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

, usually as coal

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 and coke

Coke (fuel)

Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

, in either a blast furnace

Blast furnace

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...

 or an electric arc furnace

Electric arc furnace

An electric arc furnace is a furnace that heats charged material by means of an electric arc.Arc furnaces range in size from small units of approximately one ton capacity up to about 400 ton units used for secondary steelmaking...

-type system, called a submerged arc furnace. The oxides undergo carbothermal reduction in the furnaces, producing the ferromanganese. Ferromanganese is used as a deoxidizer

Deoxidizer

A deoxidizer is a chemical used in a reaction or process to remove oxygen. In comparison with antioxidants, deoxidizers are not used for stabilization during storage but for oxygen removal during manufacture...

 for steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

.

Henry Bessemer invented the use of ferromanganese as a method of introducing manganese in controlled proportions during the production of steel. The advantage of combining powdered iron oxide and manganese oxide together is the lower melting point of the combined alloy compared to pure manganese oxide.

A North American standard specification is ASTM A99. The ten grades covered under this specification includes;

• Standard ferromanganese
• Medium-carbon ferromanganese
• Low-carbon ferromanganese

A similar material is a pig iron

Pig iron

Pig iron is the intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux. Charcoal and anthracite have also been used as fuel...

 with high content of manganese, is called spiegeleisen

Spiegeleisen

Spiegeleisen is a ferromanganese alloy containing approximately 15% manganese and small quantities of carbon and silicon. Historically, this was the standard form in which manganese was traded and used in steel making...

.