Editing Mineral wool (section)

=== Crystalline silica ===

Amorphous high-temperature mineral wool (AES and ASW) is produced from a molten glass stream which is aerosolized by a jet of high-pressure air or by letting the stream impinge onto spinning wheels. The droplets are drawn into fibers; the mass of both fibers and remaining droplets cool very rapidly so that no crystalline phases may form.

When amorphous high-temperature mineral wool is installed and used in high-temperature applications such as industrial furnaces, at least one face may be exposed to conditions causing the fibers to partially devitrify. Depending on the chemical composition of the glassy fiber and the time and temperature to which the materials are exposed, different stable crystalline phases may form.

In after-use high-temperature mineral wool [[crystalline silica]] crystals are embedded in a matrix composed of other crystals and glasses. Experimental results on the biological activity of after-use high-temperature mineral wool have not demonstrated any hazardous activity that could be related to any form of silica they may contain.