Ferrosilicon slag is a byproduct produced during the ferrosilicon smelting process. Its main components are silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), calcium oxide (CaO), ferrous oxide (FeO), etc. It also contains a small amount of valuable elements such as silicon, silicon carbide and manganese. It is usually dark gray or black in appearance, with a density generally between 2.0-2.5g/cm³, a high melting point, usually above 1500℃, and good fire resistance. During the smelting process of ferrosilicon, silica reacts with reducing agents at high temperatures to produce ferrosilicon, and at the same time produces some impurities and compounds that cannot be completely reacted, which form ferrosilicon slag.

Ferrosilicon slag

chemical composition

Slicon Slag
Type	Si	Ca	S	P	C
Type	≥	≤
SiliconSlag45	45	5	0.1	0.05	5
SiliconSlag50	50	5	0.1	0.05	5
SiliconSlag55	55	5	0.1	0.05	5
SiliconSlag60	60	4	0.1	0.05	5
SiliconSlag65	65	4	0.1	0.05	5
SiliconSlag70	70	3	0.1	0.05	3.5

Products Uses

As raw material for alloy production:

It can be used as a furnace charge for smelting manganese silicon alloys. Elements such as silicon and manganese in ferrosilicon slag can participate in the reaction, reducing the use of raw materials such as silica and coke, and saving electricity.

Used in steelmaking and ironmaking:

In steelmaking, the silicon in ferrosilicon slag reacts with oxygen in the furnace to generate SiO₂, releasing a large amount of heat, increasing the temperature in the furnace, reducing the amount of coke used, and increasing the fluidity of molten iron, which is conducive to slag removal and impurity removal, improving the grade of pig iron, and improving the toughness and machinability of cast iron.

Remelting:

Many ferroalloy manufacturers use ferrosilicon slag for the remelting of ferrosilicon and silicon metal, which can increase the silicon content in the product and reduce the smelting cost.

Cement production:

It can be used as an admixture in cement production to improve the performance of cement, and improve the strength and durability of cement.

Preparation of concrete and mortar:

After treatment, ferrosilicon slag can be used as aggregate or filler for the preparation of concrete and mortar to improve its performance.

Making slag bricks:

Mixed with gypsum, lime, etc. in a certain proportion, it can be made into slag bricks through wheel rolling, mixing, molding, curing and other processes for building walls, etc.

Preparation of microcrystalline glass and ceramics:

The components in ferrosilicon slag can be used to prepare high-performance materials such as microcrystalline glass and ceramics, improving the performance and quality of the materials.

Making silicon briquettes:

Ferrosilicon slag is collected and purified by technology and pressed into balls. It can be used as a new type of metallurgical material with low cost and good use effect.

Ferrosilicon slag