Understanding the hazard potentials of toxic fumes.
Eighth High Tech Seminar, Blasting Technology, Instrumentation and Explosives Applications, 1998 Jul; :363-382
Toxic fumes cause fatal and nonfatal incidents in underground mining, where the working environment tends to trap the fumes, hindering the restoration of nonharmful conditions. Workers can underestimate the residual fume toxicity and return to the work site too quickly. The toxic fumes from charge explosions depend upon a number things: formulation ingredients, mixture uniformity, water resistance, hole contaminates, rock hardness, and dust interactions. Hole-to-hole shock waves and rift compressions can partially desensitize charges, ruin the action kinetics, and worsen the fume toxicity. Traditionally the fume hazards for candidate explosives are resolved for a restrictive set or tally of theoretical or measured fume components, transformed to standard reference conditions. The relative fume toxicity RFT is the resultant influence reckoned from a formulated sum of concentrations within the tally that are unweighted or weighted with chosen multiplying constants. The RFT result is compared to a rule criterion that represents the worst case tolerable fume toxicity stipulated by regulations or otherwise. The ranking or comparison of different hazard potentials that would otherwise remain unwieldy is rendered tractable by the common format of the RFT notation. The RFT rules utilized within the industry yield disparate rankings, rather than focusing on a reliable unique result, raising questions about their worthiness as hazard potentials. This irregularity remains a foremost issue within this report, illustrated with fume results from instrumented shots and thermodynamic reaction chemistry code TDRC. The work principle from thermodynamics restricted by a chosen constraint is utilized for theoretical fume resolution rather than more traditional hydrodynamic detonation theory. This circumvents with a recognized difficulty related to the nonideal detonation reaction characteristics of typical mining explosives. Tabulated discrepancies from the different RFT rules typically outweigh the uncertainty in fume component concentrations, regardless of the type of resolving used. The untrained or unwary worker can misinterpret and rely on the formulated nature of the RFT rankings, without questioning their limitations, and thereby gravely underestimate the real fume toxicity. In underground mines, where fume dilution is naturally restricted, such misjudgments in respiratory hazards can invite unwarranted risks. Workers who reflect upon this report's observations will hopefully remain wary of weakness in the formulated RFT hazard potentials, gain a wider perspective, raise work site questions, and make resolutions to work under safer conditions.
Underground-mining; Shock-waves; Fumes; Explosives; Mining-industry; Mathematical-models;
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, Pittsburgh, PA 15236
Other Occupational Concerns
Eighth High Tech Seminar, Blasting Technology, Instrumentation and Explosives Applications