In general, some 70% of dusts are explosive, and given an adequate ignition source and appropriate dust/air concentration, dust clouds can cause explosions. Combustible dust cloud explosions in powder handling facilities generally occur because of:
Some materials will not present a dust explosion hazard due to their granular nature. However, during the processing of these materials, it is possible to create finely divided dust, which can be explosible. This applies to the operations where fine dust is intentionally generated (e.g., during milling) and/or unintentionally generated (e.g., during grinding, sawing, polishing or due to material attrition). Non-explosive materials such as sand or silica could become explosive if mixed with other explosible material (such as organic and/or metal dust) in adequate quantities. Hence, it is important to screen representative samples to determine if a mixture of material is explosive or not.