Molten Aluminum-Water Explosion Initiation Mechanism Study.
NIOSH 1975 Sep:256 pages
Molten aluminum (7429905) bleed outs occurring during direct chill (DC) operations which result in explosions of varying degrees of severity when the aluminum flows into the quenching water used in the chill process are reviewed. Those aspects of the interaction which led to explosions were studied to identify initiation mechanisms which were consistent with commercial experience, and would account for the randomness with which explosions occurred. The most probable initiation mechanism has been identified as spontaneous nucleation of liquid quench water contained in quench pit surface capillaries. The molten aluminum is separated from this liquid water by a vapor film which must be collapsed to provide intimate contact between molten aluminum and liquid water. The most probable and most frequent trigger mechanism producing the required contact has been identified as an impact generated shock, which is produced by the aluminum flow over quench pit surface. Current aluminum industry safety practices which emphasize the elimination of the surface cavities which trap the liquid water required for initiation of the explosion are supported.
Contract-099-73-0027; NIOSH-Publication; Explosion-prevention; Industrial-processes; Safety-practices; Metal-industry; Light-metals;
NTIS Accession No.
NIOSH, Cincinnati, Ohio, Final Report