Article,
Tantalum dust deflagration in a bag filter dust-collecting device
Journal of Hazardous Materials, 77 (1-3): 33--42 (October 2000)
DOI: http://dx.doi.org/10.1016/S0304-3894(00)00242-9
Abstract
An accidental tantalum powder deflagration with casualties occurred
during the operation of a bag filter dust-collecting device. To understand
the mechanism of the incident and its material hazards, experiments
for determining the combustibility and ignition characteristics of
the tantalum powder were performed. The magnitude of the tantalum
dust explosion is classified as severe (Kst=273), contrary to the
classification found in the preceding literature. The minimum ignition
energies for both a dust cloud and a dust layer of the tantalum powder
were also found to be far lower than previous values. Judging from
the observation of the surface with an SEM, the coral-like structure
of each particle of the tantalum powder can enhance its fire and
explosion hazards and affect its sensitivity to electrostatic sparks
by increasing in particle surface area. A thin, non-conductive oxide
layer of the tantalum powder surface has a high resistivity and generates
electrostatic charge when rubbed with conductive materials like the
wall of the collecting device. The authors conclude that the possible
cause of the ignition was electrostatic discharge resulting from
charging electrostatically.
