Carbon felt is a major element in many alloy products, so carbon felt purification plays an important role in alloy production. Meanwhile, in the smelting process of metal silicon, silica, ore, etc. are usually used. Silicon slag will also be produced during the smelting process, and silicon slag also contains a certain amount of industrial carbon felt, so we can use carbon felt slag to further purify carbon felt.

The first step is to separate the obvious light-colored slag and dark-colored slag from the silicon slag with a manual hammer, and then use the separation principle to further separate the silicon content in the silicon slag.

Impurities in silicon slag exist in two forms: reduced and unreduced. In industrial silicon, a flocculant composed of Na2O5~50%, SiO250~95% or Na2O5~50%, SiO250~95%, MgO and CaO is added to industrial silicon. With 35% flux, the melting point of the slag can be reduced from the original 1450 to about 1480 and then down to about 1000. It can also reduce the density of slag, increase its viscosity and surface tension, which is beneficial to the separation of slag and silicon.

The second part is smelting separation, mainly to separate impurities in molten silicon.

An oxidation reaction between aluminum and calcium and the synthetic flux takes place and is removed. The oxidation rate constant of aluminum and calcium has a linear relationship with temperature, and the oxidation process of aluminum and calcium is carried out in the region close to the diffusion. The amount of flux added is generally 10-20% (mass) of refined industrial silicon. The batching work is required to be accurate, even and timely. The quality of the batching work has an important impact on the output of the product, the unit consumption of raw materials and the cost, and even determines whether the carbon felt purification process can be carried out.