Silicon metal is typically classified into different grades based on the amount of impurities, specifically iron (Fe), aluminum (Al), and calcium (Ca). The grades are defined by their chemical composition, and the common ones include:
Fe ≤ 0.5%, Al ≤ 0.5%, Ca ≤ 0.3%
The most economical grade, widely used in aluminum alloys and the chemical industry.
Fe ≤ 0.4%, Al ≤ 0.4%, Ca ≤ 0.1%
Higher purity than 553, commonly used in applications requiring more stringent quality control, such as in aluminum casting and solar industries.
Fe ≤ 0.3%, Al ≤ 0.3%, Ca ≤ 0.03%
A high-purity grade used in the production of specialized aluminum alloys and the chemical sector.
Fe ≤ 0.2%, Al ≤ 0.2%, Ca ≤ 0.02%
Very high purity, typically used in electronic and photovoltaic applications, such as the production of solar-grade silicon.
Fe ≤ 0.1%, Al ≤ 0.1%, Ca ≤ 0.01%
Ultra-pure grade, mainly for the production of polysilicon used in semiconductors and solar panels.
These are the most common specifications. However, there are also other special grades that might be tailored to specific industrial applications or requirements. The lower the impurity levels, the higher the grade and price.
