Determination of crystalline silica in silica fume.
Silica fume is formed as a by-product in the manufacture of silicon from quartzite. This paper describes an analytical method for the determination of crystalline silica in silica fume. The crystalline silica was determined after removal of amorphous silica from the fume. A gravimetric method was developed for the determination of the total crystalline silica in the fume, while the cascade impactor technique was used to determine the crystalline content in the -10 microm fraction. X-Ray diffraction, scanning electron microscopy and particle size distributions were used to validate the steps in the analytical procedure. The total crystalline silica content was found to vary from 2.7 to 8.6% with an RSD of +/-2%, while the crystalline silica content of the -10 microm fraction was 0.23 to 0.55% with an RSD of +/-10%. A knowledge of the crystalline silica content of silica fume is of great importance in the area of Occupational Health and Safety. The samples surveyed were shown to have levels of crystalline silica in the respirable fraction well within the draft guidelines for silica fume. It is proposed that this method be accepted as a standard method for the determination of crystalline silica in silica fume.
Fletcher
A
A
School of Applied Chemistry, Curtin University, PO Box U1987, Perth Western Australia 6001, Australia.
Phillips
D
D
Barrow
I
I