(203e) Characterisation of Powder Triboelectric Properties to Prevent Dust Explosions

When two particles are colliding or sliding on each other, electric charges could be exchanged at the surfaces. This contact electrification called triboelectric effect is an old fundamental scientific subject. However, despite many studies dedicated to this subject, the fundamental mechanisms behind the triboelectric effect are not fully understood. In particular, the charging of objects composed by the same material and charging of fine powders need deeper investigations. Even the basic question related to the nature of the transferred charges (electrons, ions or material) is still debated. The difficulties are related to a lack of fundamental knowledge but also to the difficulty to perform measurements when associating the complexities of particulate systems and electrostatics.

In dusty environment, electrostatic discharges might lead to fire and explosions. According to [1] one dust explosion occurs each day in Germany and every tenth explosion is caused by static electricity. According to [2], 70% of 153 industrial accidents that occurred in Japan over the past 50 years were also attributable to static electricity. Therefore, a better knowledge of the physical mechanisms and the existence of improved measurement techniques could have huge positive consequences.

During the last years, we developed a measurement method able to measure the ability of a powder to electrostatically charge during a flow [3]. The instrument called GranuCharge and commercialized by GranuTools is based on this method. This measurement allows to predict the chargeability of grains from a laboratory measurement and therefore to estimate the probability to obtain dust explosion inside a production plant. Moreover, a series of measurements and also numerical simulations have been performed to better understand the fundamental mechanisms leading to triboelectric charge build-up in particulate materials leading potentially to dust explosion.

[1] M. Glor, Ignition hazard due to static electricity in particulate processes, Powder Technology 135, 223 (2003).

[2] A. Ohsawa, Statistical analysis of fires and explosions attributed to static electricity over the last 50 years in Japanese industry, Journal of Physics: Conference Series 301, 012033 (2011).

[3] A. Rescaglio, F. De Smet, L. Aerts, & G. Lumay, Tribo-electrification of pharmaceutical powder blends, Particulate Science and Technology 37, 1024 (2019)