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Mining Publication: Scaled Cloud Model for Released Toxic Fumes

NOTE: This page is archived for historical purposes and is no longer being maintained or updated. Contact NIOSH Mining if you need an accessible version.

Original creation date: January 2001

Image of publication Scaled Cloud Model for Released Toxic Fumes

Recognizing the dynamic nature and possible range of toxic concentrations in the impending fume cloud prior to undertaking explosive blasting can reduce potential hazards and mitigate related incidents. The scaled cloud model was formulated to predict the relevant (major) toxic components in fume clouds released by nonideal mining explosives used for surface blasting. Natural turbulence unceasingly disperses the toxic molecules, widening (inflating) the fume cloud while diluting the concentrations, ultimately rendering nonhazardous conditions. The threshold cloud size depends upon the type and quantity of total explosives used and the cloud's thermodynamic condition. Though the scaled theory works for fume clouds with irregular (odd) shape, and equivalent upright cylindrical form is useful for rendering simple risk/hazard scenarios. The cylinder's projection downward on the underlying terrain yields a circular 'shadow' marking the region threatened, thereby permitting a rough estimation of the potential hazards, were the cloud to settle down there. Wind causes the cloud to drift while it expands, so the shadow travels while it grows, until the risk/hazard process is truncated at the nonhazardous threshold.

Authors: MS Wieland

Conference Paper - January 2001

NIOSHTIC2 Number: 20021485

Proc 10th Annual High-Tech Blasting Seminar. Allentown, PA: Blasting Analysis International, Inc., 2001 Jan; :1-18