Model No.	Chemical Composition (%)
	Si	Fe	Al	Ca
	≥	≤
Si-97	97.0	2.0	/	0.5
Si-95	95.0	3.0	/	/
Si-93	93.0	3.5	/	/

Off grade silicon metal is a model of silicon metal. It is obtained by smelting silica and reducing agents in an electric arc furnace and is the main raw material for polycrystalline silicon, organic silicon and silicon-aluminum alloys. It have other names like industrial silicon or crystalline silicon. Silica containing silicon oxide and carbonaceous reducing agents are its main raw materials.

The production method of off-grade silicon metal is: heating the charge to above 2000°C through graphite electrodes and arc heat, the the carbon reducing agent will reduce silicon dioxide and generate liquid silicon. Then, mixture of oxygen and air came at the bottom of the silicon ladle to remove calcium , aluminum and other impurities. This is also a common production method for higher grade si-metal.

Generally speaking, the content of silicon metal is more than 98%. The most common metallurgical grade model is Silicon 553. It contains Si 98.5% minimum. So, off Grade Silicon refers to silicon metal with a silicon content of less than 98%. Among these models, the most common is Silicon Metal 97.

In addition, Off grade metal also contains other models like silicon metal 96, silicon metal 95, silicon metal 94, silicon metal 93. Except off grade silicon, there are also other 2 by-products: silicon carbon alloy and Silicon slag. The silicon in those 2 models are evern lower.

As the main raw material of silicon chemical industry, industrial silicon is used downstream in polycrystalline silicon, organic silicon and silicon-aluminum alloys. Off grade silicon metal is cheaper and more used in the aluminum alloy industry than other models. Silicon-aluminum alloy usually with a silicon content of 4% to 13%. Adding off-grade silicon to aluminum alloy can improve its casting performance, corrosion resistance and air tightness.