Silicon metal manufacturing process

Silicon metal is produced on a large scale through the reduction of silica, which is the chemical compound present in sand, with carbon in an electric arc furnace. The process involves several steps including the preparation of raw materials, the reduction of silica, and the refining of silicon metal.

Firstly, before reducing silica, raw materials such as coal, wood chips, and silica are mixed and dried thoroughly to remove any moisture. Then the materials are placed into an electric arc furnace and heated to a temperature of around 2000°C. The heat is generated by an electric arc that is produced between two graphite electrodes placed on the top of the furnace.

Secondly, once the furnace is heated to the required temperature, powdered coke or anthracite is added to the mixture. The coke acts as a reducing agent, which removes the oxygen from the silica to form silicon dioxide and carbon monoxide. The silicon dioxide then reacts with the remaining carbon in the furnace to produce silicon metal.

Lastly, the silicon metal produced from the electric arc furnace undergoes further refining to remove impurities such as sulfur, phosphorus, and other metals. It is then cast into ingots for further processing or sold as a raw material to other industries.

Overall, the silicon metal manufacturing process is an energy-intensive process that requires careful control of the furnace temperature and the addition of reducing agents to produce high-quality silicon metal. The final product is a lustrous, grey, and brittle metalloid that is widely used in the electronics and solar industries.

The silicon metal manufacturing process involves reducing silica (SiO₂) with carbon in a submerged arc furnace (SAF) at high temperatures. Here's a step-by-step breakdown:

1. Raw Materials Preparation

Silica (SiO₂): High-purity quartz (≥99% SiO₂) is used.

Carbon Reductants: Petroleum coke, coal, charcoal, or wood chips.

Optional Additives: Steel chips (to aid in slag formation).

2. Crushing & Mixing

Quartz is crushed into small pieces (20-80 mm).

Carbon materials are ground and mixed with quartz in precise ratios (~3:1 SiO₂:C).

3. Smelting in Submerged Arc Furnace (SAF)

The mixture is fed into an electric arc furnace (resistance-type, 1600–2000°C).

Electrodes (graphite or Söderberg) supply power (~10-35 MVA).

Key Reactions:

SiO2+2C→Si+2CO(Main reaction)

SiO2+C→SiO+CO(Intermediate)

SiO+C→Si+CO(Secondary)

Impurities (Fe, Al, Ca) form slag (removed periodically).

4. Tapping & Refining

Molten silicon (~99% purity) is tapped from the furnace.

Refining (Optional):

Slag treatment (removes oxides).

Gas purging (O₂/Cl₂ to reduce Al, Ca).

Ladle refining (for higher grades).

5. Casting & Crushing

Silicon is poured into molds, cooled, and solidified.

The ingots are crushed, sized, and packaged.

6. Classification by Purity

Metallurgical-Grade Silicon (MG-Si): 98–99.5% Si (used in aluminum alloys, silicones).

Higher Grades: Further refined for solar (SoG-Si) or semiconductor use.

Key Challenges

High energy consumption (~10–14 MWh/ton Si).

Emissions control (CO, SiO gas, dust).

Impurity management (Fe, Al, Ca, B, P).

Environmental Considerations

CO₂ emissions: From carbon reductants (~5–6 tons CO₂/ton Si).

Waste slag: Can be recycled in construction.

Gas treatment: Filters capture SiO₂ dust.

Q: Where to buy or order silicon metal?
A: Send email to info@kexingui.com
Whatsapp/wechat: 86-17550895599