We are removing some old fire brick, fiber glass (or rock wool) heat insulation from a furnace. Can these materials contain crystalline silica?
The hazards in removal need to be evaluated if no cutting, breaking, grinding, etc., is involved there may be no hazard. In these materials devitrification (conversion of the glassy to the crystalline state) may have occurred. Devitrification can occur in fire brick, obsidian, pumice, fused silica, fiber glass, and rock wool held at elevated temperatures producing disordered crystalline silica forms. These materials should be analyzed for the type and amount of crystalline silica present before removal so that proper protection can be provided to the employee. Even without good XRD quantitative confirmation, crystalline silica may be qualitatively identified.
