Comparison of the effect of powder properties on coating transfer efficiency and dustiness in two non-electrostatic and electrostatic systems

• Published in: Innovative food science & emerging technologies Vol. 5; no. 2; pp. 191 - 198
• Main Authors: Biehl, H.L, Barringer, S.A
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2004
• Subjects: Charge; Coating systems; coatings; cohesion; Cohesiveness; density; electrostatic coating; Electrostatics; food coatings; food processing; food technology; mass transfer; Particle size; Powder coating; Coating systems; Particle size; Cohesiveness; Charge; Powder coating; Electrostatics; Industrial relevance: Powder coating is commonly used within the food industry. Uniformity of coating as well as dust and powderwaste generation are issues of importance. Electrostatic coating is one way to minimize dust. However, since food powders differ in their coating efficiency it was the purpose of this study to identify product properties of importance for the both systems commonly applied gravity fed tumble drums and pneumatically fed conveyor coating systems the data clearly provide useful information about the relationship between powder characteristics and coating efficiency in both systems and also demonstrate the advantages of electrostatic systems
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2004.02.003

Particle size, density, cohesiveness and chargeability of powders were correlated to their electrostatic and non-electrostatic transfer efficiency and dustiness in gravity fed tumble drum and pneumatically fed conveyor belt coating systems. The effect of particle size on transfer efficiency was opposite in the two systems, while the other properties were similar. For non-electrostatic coating, smaller particles give more efficient coating in the gravity drum whereas in the pneumatic conveyor system larger particles coat better. Electrostatics improves the coating efficiency of small particles so that size is no longer important in the conveyor system, while small particles continue to be better in the tumble drum. The more free-flowing the powder, the greater the non-electrostatic and electrostatic coating transfer efficiency for both systems. Electrostatic coating transfer efficiency increases in both coating systems for powders that are readily chargeable. Density was typically not significant. The powders that were worst non-electrostatically showed the greatest percent improvement with electrostatics. Small particles create more dust in both coating systems.