company news about How is ferrosilicon produced in electric arc furnaces?

Ferrosilicon (FeSi) is produced in submerged electric arc furnaces (SAF) through a high-temperature carbothermic reduction process. This method is optimized to achieve high silicon yield, controlled impurity levels, and stable large-scale production, which is why it is the global standard for FeSi manufacturing.

Below is a process-driven explanation, aligned with how industrial plants actually operate.

Ferrosilicon is not made in open arc furnaces. It requires a submerged arc furnace, characterized by:

• Carbon electrodes buried in the charge
• Temperatures above 1,900–2,000 °C
• Continuous solid-charge feeding
• Reducing atmosphere inside the furnace

This setup enables efficient reduction of silica to silicon.

• Quartz or high-purity silica (SiO₂)
  Provides the silicon to be reduced.

• Iron ore, mill scale, or steel scrap
  Supplies iron to form the Fe–Si alloy.

• Coke, coal, charcoal, or wood chips
  Remove oxygen from silica and iron oxides.

• Small amounts of limestone or other fluxes
• Control slag fluidity and impurity removal.

The liberated silicon dissolves into molten iron, forming ferrosilicon rather than free silicon metal.

Inside the SAF:

• Upper zone: Preheating and partial reduction
• Reaction zone: High-temperature silica reduction
• Lower zone: Molten FeSi and slag separation

Precise control of:

• Power input
• Charge composition
• Electrode position

is critical for:

• Silicon recovery
• Grade stability (e.g., FeSi 65 vs FeSi 75)
• Low impurity levels.

Once sufficient molten alloy accumulates:

• Furnace is tapped periodically
• Molten ferrosilicon flows out, separating from slag
• Slag is discarded or recycled depending on composition

The silicon content is controlled by:

• SiO₂ / carbon ratio
• Iron input
• Furnace temperature and residence time.

After tapping:

1. Molten FeSi is cast into molds or beds
2. Slowly cooled to prevent cracking
3. Crushed and screened into industrial sizes:
   • Lumps
   • Granules
   • Fines or powder

Particle size selection affects:

• Dissolution rate
• Oxidation loss
• Silicon recovery in steelmaking.

Each batch undergoes:

• Chemical composition analysis (Si, C, Al, Ca, P, S)
• Particle size verification
• Visual inspection for cracks and oxidation

Industrial buyers focus on:

• Stable Si percentage
• Low impurity variation
• Consistent size distribution.

Electric arc furnaces provide:

• Extremely high and controllable temperatures
• Stable reducing atmosphere
• Scalable continuous production
• High silicon yield and repeatability

Without SAF technology, commercial-grade ferrosilicon cannot be produced economically.

Ferrosilicon production involves:

1. Charging quartz, iron source, and carbon
2. High-temperature carbothermic reduction
3. Silicon dissolving into molten iron
4. Periodic tapping of molten FeSi
5. Cooling, crushing, and sizing

This process produces cost-effective, high-performance ferrosilicon essential for steelmaking and foundry operations worldwide.