Manganese alloys

Eramet is the world’s second-largest producer of manganese alloys. Its production capacity is spread over three continents, via its subsidiaries in the United States (Eramet Marietta), Norway (Eramet Norway), France (Comilog Dunkerque), and the Complexe métallurgique de Moanda (C2M) in Gabon. These six plants are located close to dynamic steelmaking zones near major markets, guaranteeing optimum supply to European and American steelmakers.

Eramet is committed to respecting the specifications of its manganese alloys across its entire product range. A commitment that has proved its worth, given the Group’s long-standing relationships with its customers.

Our manganese alloys

Manganese alloys are produced by smelting manganese ore at a temperature of around 1,600°C. This operation, known as metallurgical reduction, is carried out by adding metallurgical coke in furnaces, the vast majority of which are electric furnaces.

The sources of electricity used by Eramet’s plants in Gabon, Norway (hydroelectricity) and France (nuclear and mixed) enable the company to produce alloys with a particularly low carbon footprint.

The range of alloys produced by Eramet is very broad and includes standard products (high-carbon ferromanganese, silicomanganese), as well as so-called refined products (medium- and low-carbon ferromanganese, low-carbon silicomanganese).

Despite the small share of refined alloys in global alloy production, they represent the highest value-added products, due to their low carbon and high manganese content and their exposure to the energy and automotive markets.

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635 kt
of manganese alloys produced

43 %
reduction in CO₂ emissions by 2023 by Eramet Norway

40 M$
investments by Eramet Marietta in energy efficiency projects on air quality in over ten years

The different alloys

Silicomanganese

This is a rocky material with a silvery metallic surface. Both silicon and manganese have a significant influence on steel properties, depending on the quantity added and the combined effect with other alloying elements. Silicon and manganese have a strong affinity with oxygen and act as deoxidizers.

The use of silicomanganese adds less carbon to the steel than an equivalent basket of standard ferrosilicon 75 (FeSi 75) and high-carbon ferromanganese (HCFeMn). Computational fluid dynamics calculations show that the silicon yield of silicomanganese is higher than that of standard FeSi 75.

Low-carbon silicomanganese

Low-carbon silicomanganese (LCSiMn) comes in rock form with a silvery metallic surface. It is mainly used in stainless steel production in the AOD (Argon Oxygen Decarburization), VOD (Vaccum Oxygen Decarburization) and CLU (Creusot-Loire – Uddeholm) processes.

During decarburization, the use of low-carbon silicomanganese instead of high-carbon ferromanganese delivers productivity improvements of 4-6%. It also reduces the amount of manganese oxidized, and therefore the amount of silicon required. This may also improve furnace lining life, thanks to the use of a less fluid slag (less manganese oxide (MnO)).

Low-carbon silicomanganese can also replace manganese metal and ferrosilicon in the production of certain grades of low-carbon steel. Phosphorus input is considerably reduced, as the Mn/P ratio is much higher in low-carbon silicomanganese than in high-carbon ferromanganese.

Medium and low-carbon ferromanganese

Medium and low-carbon ferromanganese is a lumpy material with a silvery metallic surface. When added to steel, manganese has a significant influence on the structure and properties of the steel, depending on the quantity used and the effect combined with other alloying elements. It improves tensile strength, workability, toughness, hardness and abrasion resistance. It also reacts with the sulfur remaining in the steel, preventing surface cracking.

By adding manganese in the form of MC / LCFeMn instead of HCFeMn, around 80% to 93% less carbon is added to the steel (for a steel containing 2% manganese). As the alloy is delivered in lump form, it will give a higher manganese yield than electrolytic manganese delivered in flake form.

High-carbon ferromanganese

This is a lumpy material with a metallic surface that becomes coated with a dark layer of oxides during storage. When added to steel, manganese has a significant influence on the structure and properties of the steel, depending on the quantity used and the effect combined with other alloying elements.

Manganese is the least expensive of the alloying elements that improve key mechanical properties. It improves tensile strength, workability, toughness, hardness and abrasion resistance. It also reacts with the sulfur remaining in the steel, preventing surface cracking.

Manganese dioxide (MnO)

The production of manganese dioxide (MnO) is a new product offered to customers by Comilog at its Complexe Métallurgique de Moanda (CMM).

Its high manganese content (>60% guaranteed) makes it ideal for manganese chemistry, such as sulfate production for agrochemicals, batteries and EMM. It is also used as an input in the production of EMD (Electrolytic Manganese Dioxide) for alkaline batteries.