Silicon metal, also known as crystalline silicon or industrial silicon, is primarily used as an additive for non-ferrous alloys. Silicon metal is made fromquartzandcokeThe content of silicon element, the main component of the product smelted in the electric furnace, is about 98% (in recent years, the content of 99.99% Si is also contained in silicon metal), and the rest of the impurities are iron, aluminum, calcium, etc.

The classification of silicon metal is usually classified according to the content of the three main impurities contained in the composition of silicon metal: iron, aluminum, and calcium. According to the content of iron, aluminum and calcium in silicon metal, silicon metal can be divided into 553, 441, 411, 421, 3303, 3305, 2202, 2502, 1501, 1101 and other different grades.

Industrially, silicon metal is usually produced from carbon-reduced silica in electric furnaces. Chemical Reaction Equation: SiO2 + 2C → Si + 2CO The purity of silicon prepared in this way is 97~98%, which is called silicon metal. Then it is melted and recrystallized, and the impurities are removed with acid to obtain silicon metal with a purity of 99.7~99.8%.

Silicon metal is mainly composed of silicon, so it has similar properties to silicon. There are two allotropic forms of silicon: amorphous silicon and crystalline silicon. Amorphous silicon is a grayish-black powder that is actually also a microcrystalline. Crystalline silicon has the crystal structure and semiconductor properties of diamond, melting point 1410 °C, boiling point 2355 °C, Mohs hardness 7, brittleness. Amorphous silicon is chemically active and can burn violently in oxygen. It reacts with non-metals such as halogen, nitrogen, and carbon at high temperatures, and can also react with metals such as magnesium, calcium, and iron to form silicides. Amorphous silicon is insoluble in almost all inorganic and organic acids, including hydrofluoric acid, but it is soluble in a mixture of nitric and hydrofluoric acids. The concentrated sodium hydroxide solution can dissolve amorphous silicon and release hydrogen gas. Crystalline silicon is relatively inactive, it does not combine with oxygen even at high temperatures, it is insoluble in any kind of inorganic and organic acids, but soluble in mixed acids of nitric acid and hydrofluoric acid and concentrated sodium hydroxide solution.