Page 48 - Dust Explosions in the Process Industries

Dust Explosions:An Overview 27

to support its combustion; and we found the dust adhering to the face of the pillars, props, and walls
in the direction of, and on the side towards the explosion, increasing gradually to a certain distance,
as we neared the place of ignition. This deposit was in some parts half an inch, and in others almost
an inch thick it adhered together in a friable coked state; when examined with the glass it presented
the fused round fisrm of burnt coal dust, and when examined chemically, and compared with the coal
itself reduced to powder, was found deprived of the greater portion of the bitumen, and in some
instances entirely destitute of it. There is every reason to believe that much coal-gas was made from
this dust in the very air itself of the mine by the flame of the fire-damp, which raised and swept it
along; and much of the carbon of this dust remained unburned only for want of air.
During the 150-200 years that have passed since the days of Morozzo and Faraday,
the phenomenon of dust explosions has become fully accepted as a serious industrial
hazard. Furthermore, since that time, the expanding chemical and metallurgical indus-
tries have given birth to a steadily increasing number of new, finely divided combustible
solid materials that have caused dust explosions to remain a significant hazard in many
industries. As an important element in the constant efforts to fight the dust explosion
hazard, actual accidents are carefully investigated. In some countries, valuable statisti-
cal records are available, some of which are discussed in the following sections.

1.2.2
DUST EXPLOSIONS IN THE UNITED STATES, 1900-1 956

The National Fire Protection Association published a report of important dust explosions
in the United States from 1900 to 1956 (NFPA, 1957).The report gives informative details
of a selection of 75 of the most serious and recent of the 1123explosions recorded. The
selection covers a wide range of dusts from all the categories-wood, food and feed,
metals, plastics, coal, paper, and chemicals. In addition, each of the 1123 explosions is
mentioned briefly individually by specifying the date, location, dust involved, probable
ignition source, number of fatalities and injuries, and material losses.
Table I .3 gives an overall summary of the consequences of explosions involving vani-
ous dust categories.The table illustrates some interesting differences.For example,the metal
dust explosions, representing 7.1% of the total number of explosions, were responsible

Table 1.3 Dust explosions in the United States, 1900-1 956: fatalities, injuries, and material losses
in a sample of 1123 accidental explosions

*Numerical value in U.S. dollars at year of explosion, not inflated.
Source: Data from NFPA, 1957.