Ferromanganese

Ferromanganese is a ferroalloy with high manganese content (high-carbon ferromanganese can contain as much as 80% Mn by weight). It is made by heating a mixture of the oxides MnO2 and Fe2O3, with carbon (usually as coal and coke) in either a blast furnace or an electric arc furnace-type system, called a submerged arc furnace. The oxides undergo carbothermal reduction in the furnaces, producing the ferromanganese. Ferromanganese is used as a deoxidizer for steel.
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 with high content of manganese, is called spiegeleisen, or specular pig iron.
1. Production of Ferromanganese:
Ferromanganese is produced through a carbothermal reduction process, where a mixture of manganese dioxide (MnO2) and iron oxide (Fe2O3) is heated with carbon sources like coal and coke.
The reaction occurs in either a blast furnace or a submerged arc furnace, resulting in the formation of ferromanganese.
The manganese content in ferromanganese can vary, with high-carbon ferromanganese containing up to 80% manganese by weight.
2. Applications in Steel Industry:
Ferromanganese is primarily used as a deoxidizer in the steel-making process, helping to remove impurities and enhance steel quality.
It acts as an alloying agent, contributing to the desired properties of steel such as increased strength, hardness, and resistance to wear and corrosion.
Different grades of ferromanganese (standard, medium-carbon, and low-carbon) cater to specific steel compositions and industrial needs.
3. ASTM A99 Standard Specification:
ASTM A99 is a widely followed North American standard specification that outlines the various grades of ferromanganese available for industrial use.
The ten grades covered under this specification include standard ferromanganese, medium-carbon ferromanganese, and low-carbon ferromanganese, among others.
This standardization ensures consistency and quality control in the production and application of ferromanganese.
4. Similar Material: Spiegeleisen (Specular Pig Iron):
Spiegeleisen is another material with a high manganese content used in the steel industry, resembling ferromanganese in some applications.
It plays a crucial role in modifying the properties of iron and steel, contributing to their strength and durability.
While both ferromanganese and spiegeleisen share similarities, they offer unique characteristics, making them suitable for specific metallurgical purposes.
5. Beyond Steel Industry:
Ferromanganese finds applications beyond the steel industry, including non-ferrous metallurgy, where it acts as a reducing agent for the production of metals like molybdenum and chromium.
The manufacturing of stainless steel relies on the precise control of manganese content in ferromanganese to achieve specific product properties.
6. Environmental Considerations:
The production of ferromanganese, particularly through traditional methods using carbon sources, leads to carbon dioxide emissions and contributes to greenhouse gas effects.
Ongoing efforts are being made to explore alternative production methods or develop carbon-neutral processes to reduce the environmental impact of ferromanganese production.
7. Future Outlook:
As technology advances and sustainability concerns grow, there may be further developments in the production and application of ferromanganese.
Researchers and industry experts are likely to focus on optimizing production processes, reducing environmental impact, and exploring new applications for this versatile ferroalloy.
In conclusion, ferromanganese is a crucial component in the steel-making process, offering various grades for different industrial needs. Its applications extend beyond steel to non-ferrous metallurgy and stainless steel production. As sustainability becomes a more significant concern, the industry is actively seeking ways to minimize the environmental impact of ferromanganese production while exploring new possibilities for its utilization.
History
In 1856, Robert Forester Mushet "used manganese to improve the ability of steel produced by the Bessemer process to withstand rolling and forging at elevated temperatures."
In 1860, 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.
In 1872, Lambert von Pantz produced ferromanganese in a blast furnace, with significantly higher manganese content than was previously possible (37% instead of the previous 12%). This won his company international recognition, including a gold medal at the 1873 World Exposition in Vienna and a certificate of award at the 1876 Centennial Exposition in Pennsylvania.
In an 1876 article, MF Gautier explained that the magnetic oxide needs to be slagged off by the addition of manganese (then in the form of spiegel iron) in order to befit it for rolling.
Gallery
Standard Ferromanganese
Standard ferromanganese, also known as high-carbon ferromanganese, is one of the manganese ferroalloys smelted directly from manganese ores. Manganese content ranges from 74 to 82% and the carbon content from 7 to 7.5%. It is produced either by a blast furnace or a submerged arc furnace. The alloy is smelted either by high-manganese slag or discard slag practices. High-manganese slag practice operates with slag containing 30–42%Mn. Because of its high manganese value, the slag is recycled as feed for the production of manganese metal by electrolytic process or for the production of silicomanganese alloy. Addition of lime is avoided to keep the manganese content high. The discard slag practice operates with slag containing 10–20%Mn. This level of content is too low to extract further manganese value economically. Lime is used to keep the manganese content low in slag.
Applications
See also
Mangalloy
Ferromanganese Nodules
References
Further reading
Ferroalloys
Deoxidizers
Manganese