Popular science of metal silicon manufacturing process

About metal silicon, I believe many people are curious about its manufacturing process. Some people may ask, is the sand we often see the precursor of metal silicon? Ok, let's give you a score today.

What is metal silicon

Although metal silicon is extracted from silica, not all silica is suitable for making metal silicon. Metal silicon, also known as industrial silicon and crystalline silicon. It is obtained by reducing carbon to silica. Metallic silicon is generally used in aluminum articles or as an additive to non-ferrous alloys.

1. Specification of silicon metal
2. Specification of silicon metal powder

Metal silicon manufacturing process

At present, the production of metallic silicon in China uses the carbon thermal method, and its production process is as follows:

Generally used silica is used as raw material, petroleum coke, charcoal, wood chips, low-ash coal and the like as reducing agents, which are smelted at high temperature in a mine electric furnace to reduce metal silicon from silica, which is a slag-free submerged arc high-temperature melting process.

The use of quartz sand as raw material for smelting metal silicon, including quartz sand block, preparation of charge and ore furnace smelting several steps. A method of smelting in a submerged arc furnace using silica and a carbonaceous reducing agent. The silicon thus obtained has a purity of 97% to 98%, and such silicon can be generally used for metallurgical purposes. If higher grade silicon is to be obtained, it needs to be refined to remove impurities to obtain metal silicon having a purity of 99.7% to 99.8%.

Chemical reaction

It is generally believed that smelting silicon metal is such a reaction:

SiO2 + C -> Si + CO2 ?

But actually involve at least 10 reactions and side reactions:

SiO2 + 3 C -> SiC + 2 CO ........(1)

2SiO2 + SiC -> 3 SiO + CO ........(2)

SiO2 + 2 SiC -> 3 Si + 2 CO ........(3)

2SiO + O2 -> 2SiO2 ........(9)

Therefore, the ordinary sand we see everyday is not the real raw material of metal silicon, but the quartz sand used in the above-mentioned industrial production, and has undergone a multi-step reaction to complete the transformation from sand to metal silicon.