US EPA

1686461 

Journal Article 

A study on post blast generation of nitrogen dioxide 

Lawrence, LD; INT SOC EXPLOS ENGINEERS 

1996 

PROCEEDINGS OF THE TWENTY-SECOND ANNUAL CONFERENCE ON EXPLOSIVES AND BLASTING TECHNIQUE, VOL II 

89-100 

WOS:A1996BG72F00007 

Certain blasting applications are more prone to the generation of significant levels of nitrogen dioxide post blast fumes, more commonly referred to as after blast smoke, generally ranging in color from dark yellow to bright red. This paper reviews basic background chemistry defining the observed fumes and attempts to correlate geology, Mast design, and explosive composition effects on the level of nitrogen dioxide that can be observed in various blasting conditions. Additionally, a test setting for evaluating the generation of post blast fumes is presented with pertinent test data detailing generic explosive formulation modifications which effect the overall level of post detonation generation of nitrogen dioxide. Scaled up field trials were completed to evaluate the results obtained using data generated from the test model. Specifically, deep, wet blasting applications in softer geologies with reduced confinement appear to promote the generation of nitric oxide from the explosive composition within the borehole due to partial reaction of the nitrates contained in commercial explosives. As the nitric oxide is released from the muck pile following the detonation of the blast pattern, the gas is readily oxidized to form the colorful after blast fumes of nitrogen dioxide. Using the experimental testing procedure it has been determined that variations to the explosive composition which affect detonation velocity and explosion temperature seem to have a significant effect on the level of nitric oxide formed during a less than ideal detonation. Additional chemical additives to reduce the level of nitric oxide which results from a less than ideal detonation front have been evaluated using the proposed test procedure. In general, higher detonation velocities or compositions with higher explosion temperatures compared to existing control compositions are significant in minimizing observed formation of nitrogen dioxide in the testing applications.