Abstract
Electrostatic charges on particles of quartz and coal of different ranks were measured and the results were correlated with the agglomeration behavior of these materials. It was observed that the particles in ambient air carried both positive and negative charges. The extent of charging was found to be a function of material type, coal rank, degree of aging in air, and humidity. The total charge on particles increased with an increase in the humidity for quartz and coal samples, whereas it decreased with an increase in the aging time. The numbers of positively and negatively charged particles were approximately equal for all the conditions studied. For quartz particles, the numbers were a function of humidity, however. The extent of agglomeration of particles in air was also found to be a function of material type and humidity. The charging mechanisms and the role of electrostatic charge on the extent of agglomeration were discussed.