Alumina-silica brick of 60% Al2O3 class or lower (including fireclay) can contain a small amount of “free” or uncombined crystalline silica. Not all refractory bricks contain free silica, as its presence complicates manufacture of the brick, and certain silica phases—like cristobalite—contribute to accelerated wear.
It is well known that free silica, as quartz or cristobalite, is a respiratory
hazard. Since cristobalite is the expected phase in fired alumina-silica brick, it is of the most potential concern. It is inexpensive to determine if a brick contains quartz or cristobalite. The issue is sawing of the brick during masonry construction. Wet sawing eliminates dust exposure, and it should be used if there are concerns about silica exposure.
Alumina-chrome bricks can form traces of hexavalent chromium (Crþ6) if the bricks are used above 12508C and are in contact with lime-rich phases. Used refractories might be checked for hexavalent chromium to ensure that any required disposal regulations are met.
Alumina-silica brick of 60% Al2O3 class or lower (including fireclay) can contain a small amount of “free” or uncombined crystalline silica. Not all refractory bricks contain free silica, as its presence complicates manufacture of the brick, and certain silica phases—like cristobalite—contribute to accelerated wear.
It is well known that free silica, as quartz or cristobalite, is a respiratory
hazard. Since cristobalite is the expected phase in fired alumina-silica brick, it is of the most potential concern. It is inexpensive to determine if a brick contains quartz or cristobalite. The issue is sawing of the brick during masonry construction. Wet sawing eliminates dust exposure, and it should be used if there are concerns about silica exposure.
Alumina-chrome bricks can form traces of hexavalent chromium (Crþ6) if the bricks are used above 12508C and are in contact with lime-rich phases. Used refractories might be checked for hexavalent chromium to ensure that any required disposal regulations are met.
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