US EPA

2072364 

Journal Article 

Manganese Mill Dust Explosion 

Senecal, JA 

1991 

Yes 

Journal of Loss Prevention in the Process Industries
ISSN: 0950-4230 

NIOSH/00206508 

4 

5 

332-337 

10.1016/0950-4230(91)80046-W 

WOS:A1991GK27100006 

An incident in which a manufacturer of metal powders experienced a process dust explosion in a manganese (7439965) pulverizing tower during an unscheduled maintenance procedure is presented. The day of the event, the classifier screen deck became plugged with a large quantity of very fine powder, less than 200 mesh. Before the work crew opened the classifier, they shut off power to the comminuting tower operating units by throwing an emergency switch. All operations were shut down, including oxygen monitoring and nitrogen purge systems. Aluminum shovels were used to remove the powder accumulated on the classifier screen deck and deposit in into the inlet of the down chute. During this process, an explosion occurred. The authors conclude that a review of the incident suggested that the material back up caused an excessive grinding of manganese to a mean particle size much smaller than usual, causing the metal dust to be more easily ignitable and more violently explosive. The inadvertent shut off of the nitrogen purge system allowed the oxygen concentration to rise to levels able to support combustion. Shovelling manganese dust and dumping it down the return duct had the effect of pumping air into the system. The rubber liner of the Linatex duct was not fitted with an interior conductive element between its termini, allowing metal dust sliding down the surface to very likely undergo significant triboelectric charging. 

EXPLOSIONS; DUST; MANGANESE