The best screw shape for fine zinc oxide particles feeding

One of the most important requirements of particles feeding is a very homogeneous mass flow of fine particles. Screw feeders are among equipment used to feed particles in many industries. In this study, the performance of four single screw feeders with different pitch and blade shape screws has been studied experimentally for steady and stable feeding of fine zinc oxide particles at flow rates corresponding to laboratory scale range (under 10 g/min). The following results were obtained from this investigation: (I) the sticking problem of fine particles in angular pitch screw was solved by changing the pitch shape to circular; (II) the distribution of the fluctuations and their intensity in mass flow rates also lessen by using the circular pitch and a thin blade screw in place of the circular pitch and a thick blade screw. Also for both feeders, the feeding was often interrupted in low flow rates, but it will be disappeared by increasing the flow rate. Furthermore, the results of experiments show that the performance of the circular pitch and a thin blade screw feeder was better than other screw feeders and able to both swirl and mix the particles with different characteristics and reduce the mean aggregate size of the particle size distribution (PSD) when transmitting the zinc oxide particles. (C) 2011 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.