Ferrosilicon is a key ferroalloy material with a wide range of applications in many industries, mainly metallurgy, foundry and non-ferrous metal production.
1. Steel Industry
(1) Deoxidizer
Mechanism of action:
Silicon combines with oxygen (O₂) in molten steel to form silica (SiO₂), which forms slag that floats to the surface, thereby purifying molten steel and preventing defects such as pores and inclusions.
Advantages:
The deoxidation efficiency is higher than that of aluminum, the cost is lower, it is widely used in the production of semi-calm and completely calm steels.
Amount of material used: Approximately 3-5 kg of ferrosilicon is consumed per ton of steel (adjustable according to the type of steel).
(2) Additive for alloying elements
Destination:
Improve the strength, hardness, and corrosion resistance of steel (e.g., silicon steel, spring steel, stainless steel).
Improvement of the electromagnetic properties of steel (e.g. electrical steel with a silicon content of 3 to 5%).
Typical types of steel:
Silicon steel (electrical steel): Used in transformers and motor cores, silicon content of 2 to 5%.
Spring steel (e.g., 60Si2Mn): Silicon increases elasticity and fatigue strength.
(3) Silicon Enhancer Additive
Used to regulate the final silicon content of molten steel to ensure that the chemical composition meets standards.
2. Foundry Industry
(1) Inoculant
Function:
It is added before pouring cast iron (e.g., gray cast iron and ductile iron) to promote graphite precipitation and grain grinding.
It improves the mechanical properties (such as tensile strength and ductility) of cast iron.
Dosage: Typically 0.2 to 0.8% by weight of molten iron.
(2) Ductile iron production
Ferrosilicon is used in combination with magnesium (Mg) to stabilize the concretization reaction and ensure the spherical structure of graphite.
Grade selection: Ferrosilicon with a low aluminum content (e.g. FeSi75-Al ≤ 0.5%) is necessary in order not to interfere with the concretization effect.
3. Magnesium production (Pidgeon process)
The role of the reducing agent:
In a high-temperature vacuum furnace, ferrosilicon (usually FeSi75) reacts with calcined dolomite (MgO-CaO) to reduce magnesium metal:
2MgO+Si→2Mg↑+SiO2
Ferrosilicon requirements: high silicon content (≥75%), low aluminum content (≤0.5%), low calcium content (≤1%) to improve recovery efficiency.
Cost-effectiveness: Each ton of magnesium metal produced requires the consumption of approximately 1.1-1.2 tons of ferrosilicon, which is 30-40% of the cost of magnesium production.
4. Production of other ferroalloys
Raw Material Base: Ferrosilicon is used as an intermediate alloy for the production of calcium-silicon alloys (Ca-Si), silicon-manganese alloys (Si-Mn), etc.
For example
Calcium-silicon alloy: produced by the reaction of ferrosilicon and lime in an electric furnace, used for deep deoxidation and desulfurization of molten steel.
5. Production of welding rods
Purpose: As
a coating component of the welding bar, it improves the fluidity of the weld pool and increases the oxidation resistance and strength of the weld metal.
Choice of grade: FeSi45 or FeSi65 are usually used, with a fine particle size (0.1-1 mm).