Evaluation of flowability for granulated powder using a test of powder discharge by pressurized air

Abstract

This study experimentally and theoretically examined the flowability and the cohesiveness for powder using a test of powder discharge through an orifice by the pressurized air. The powder used consisted of two kinds of Calcium hydroxide which have different particle sizes by granulation. These sizes are 11µm and 176µm, those called Ca(OH)2 -A and -B. Cohesiveness is characterized by the Bond number which is the ratio of separation force to the gravity force. Flowability is evaluated by the relationship between the mass flow rate and the average air pressure acting on the powder bed. We found that the Bond number of Ca(OH)2 -B was much lower than Ca(OH)2 -A. The relation between the mass flow rate of the powder and the average air pressure indicates Ca(OH)2 -B is easily flowing at the lower pressure region, and Ca(OH)2 -A was scattered at the higher pressure region. This means Ca(OH)2 -B has good flowability by the particle granulation in comparison with Ca(OH)2 -A.