Determination of Dustiness of Bulk Materials

摘要

A risk of dust explosions exists wherever combustible dusts are handled and is depending not only on the established safety characteristics, but also on a parameter describing the tendency to form a dust cloud, called dustiness. A system for use in laboratories is developed and presented to measure the dustiness. The principle is that the dust concentration of the free falling bulk material is determined by a dust concentration meter, which based on light absorption and light scattering according Lambert-Beer's Law. Therefore, the dust is moved by a screw with a defined variable-speed into the measuring chamber. To avoid bonding of the particles the electrical charges are removed by a ring ionizer. The determination of a dust concentration a calibration curve is necessary to remove the extinguishing coefficient in Lambert-Beer' s Law. This is realised with a special calibration system, where the dust collected subsequently on small glass plates is weighted and analyzed with the dust concentration meter. At least a dimensionless dustiness coefficient S is introduced, which allows the characterization and classification of different types of dust. The dustiness coefficient for different dust types used in process industries is presented.