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Dust Dispersal by Explosion-induced Airflow. Entrainment by Airblast.

Authors
Singer-JM; Harris-ME; Grumer-J
Source
NTIS: PB 253 014 :50 pages
Link
NIOSHTIC No.
10000146
Abstract
In this Bureau of Mines study coal and rock dust beds were entrained by airblasts generated by gas explosions at the closed end of a 0.61- M-diameter explosion tunnel, 49.7 M long. The system was designed to simulate entrainment of mine dust deposits by accidental gas explosion at the coal face of nonintersecting mine passageways. Full-scale mine explosion trials confirmed many of the results of the explosion tunnel experiments and indicated several new features of dust entrainment. Dispersal of 20.3-Cm-long stepped dust beds located 35 m from the closed end always began during the early portion of the ascending gradient of the first transient airflow (and pressure) wave, and was usually completed before the end of the first quarter-wave period. Bulk quantities of dust were entrained simultaneously by longitudinal regression from the leading edge of the dust bed and by surface lifting of the top layer. Instantaneous threshold air velocities for bulk quantities of coal and rock dust beds in separate, mixed, and layered configurations were in the same range (5 to 30 m/sec) as previously found under steady-state velocity conditions. Selective lifting of coal dust layers from rock dust occurred when the threshold dispersal velocity of coal dust but not of the underlying rock dust was exceeded.
Publication Date
19760101
Document Type
IH; Report of Investigations
Fiscal Year
1976
NTIS Accession No.
PB-253014
NTIS Price
A04
Identifying No.
RI-8130
NIOSH Division
PRC;
Source Name
NTIS: PB 253 014
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