What is Ferromanganese?
It is also known as ferromanganese alloy or spiegeleisen, is a ferroalloy that consists of varying amounts of manganese and iron. It is produced through carbothermic reduction of mixtures of manganese oxide and iron ore in a blast furnace. It generally contains between 45-95% manganese and 5-55% iron, along with trace amounts of impurities such as carbon, phosphorus, and silicon.
Uses
It has wide applications in metallurgy and steel production. As an alloying agent, it is mainly used to deoxidize and desulfurize steel and impart strength, toughness, ductility, and wear- and tear-resistance properties to the final product Ferro Manganese increases steel’s hardness, crack resistance, and ability to resist corrosion and wear under excessive stress and pressure. Different grades of it are used at various stages of steelmaking depending on their manganese and carbon composition.
HSLA Steels
High strength low alloy (HSLA) steels designed for applications like pipelines, shipbuilding, and construction contain around 0.5-1.5% added manganese to increase corrosion resistance without compromising ductility. During steelmaking, containing 55-78% manganese is normally used as the alloying element. The manganese bonds with impurities like sulfur to form manganese sulfide, helping refine the molten metal before tapping into the ladle. This improves the quality consistency of the final HSLA steel.
Stainless Steels
Production of austenitic chromium-nickel stainless steels also requires specific amounts of manganese addition. These stainless grades typically contain around 2-20% manganese depending on the alloy design. Ferromanganese containing 65-80% manganese is suitable for producing the desired alloying effect during melting and refining stages. Manganese improves the work hardening properties and corrosion resistance of stainless steels to stresses like stress corrosion cracking.
Basic Oxygen Furnaces
In basic oxygen steelmaking (BOS), it is used at two main stages – as a recarburizer and as a main alloying element. Low-carbon ferromanganese containing 45-55% manganese helps recover the carbon level of liquid steel through BOS blowing. Medium and high carbon grades with 55-78% manganese are then added in the ladle furnace for deoxidizing and alloying the final steel composition. This ensures the steel production process adheres to tight composition specifications.
Manufacturing Process
As mentioned earlier, it is produced through carbothermic reduction of manganese and iron bearing ores in a blast furnace. The major steps in the manufacturing process are as follows:
– Blending and Preparation: Manganese oxide ores like pyrolusite and wad are mixed and blended with iron ore fines and fluxes in specific proportions.
– Agglomeration: The blended charge is agglomerated into pellets or sinters through processes like pelletization and sintering to achieve better permeability in the furnace.
– Reduction: The agglomerated feed is charged into a blast furnace along with coke as the reducing agent. At high temperatures close to 1500°C, the carbon monoxide produced reduces both iron and manganese oxides.
– Tapping and Solidification: Molten ferromanganese alloy containing 45-95% manganese and 5-55% iron is tapped from circular openings at the bottom of the furnace. It then solidifies and cools into lumps or fines.
– Refining: Final refining of the it may be done by roasting and leaching away impurities like phosphorus, if needed to meet quality standards.
Global production is dominated by major metal producing countries like China, South Africa, India, and Ukraine. In 2020, China accounted for over 50% of worldwide ferroalloy output. it demand primarily depends on economic cycles and steel industry trends. Prices of manganese ore, alloying-grade manganese, and metallurgical-grade coal also have a direct influence on it costs. With consistent growth in infrastructure projects and newer steel applications, the long-term outlook for it remains positive across most international markets. Sustainability initiatives and the rising popularity of advanced high-strength steels serve to further drive ferromanganese utilization.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.