Reducing Overall Toxic Fumes at Fixed Work Output, by Formulating

摘要

For shooting rock properly, some relatively fixed quantity of rock work is required from the total charge mass, while keeping the overall toxic fumes to a minimum. The overall fumes weighted for the toxicity of different species and taken per unit charge mass, cp, are represented by a relative fume toxicity (RFT) formula. The worst two contributions are often carbon monoxide {CO} and total nitrogen oxides {NO_x}, so the traditional Russian formula RFT-R formula suffices, though a generalized form RFT-G with more terms is worth checking. Using the work-principle model from thermodynamics, the rock work per unit charge mass, to, is found from the reduction in internal energy for the reaction zone. This resolution technique for rock-work invokes the usual assumption that the quick irreversible process occurs without notable heat transfer to the rock (adiabatic); rock-work is not resolved, when this restriction is untenable. The ratio of φ to ω yields the weighted toxic fumes divided by the rock work or the readjusted fume toxicity T, where ω = φ/ω. For convenience, graphical trends of to, ω, φ and T were normalized using reference results for a stoichiometric (ANFO) mixture of ammonium nitrate (AN) and fuel oil(FO) shot under nominal rock confinement, noted later.rnTraditional relative strengths tabulated for reported charge formulations were compared to the normalized-ω, taken as the relative strength within the work principle model. The reduction of overall fumes was investigated using non-stoichiometric and stoichiometric mixtures by readjusting some additive as well as the two ANFO ingredients. The fumes/work ratio T was used to rank five additives, yielding quite promising results for technologically difficult-to-realize rich-water ANFO mixtures (WANFO) without or with a little aluminum (AL). The comparison technique provides a rigorous theoretical framework for discovering 'reduced-fumes' 'same-work' charge formulations for rock blasting by recognizing whether they yield more desirable toxic fume results for the rock-work process, rather than the traditional isentropic (reversible-adiabatic) trajectory that wholly disregards the nature of the rock confinement. The reductions in the overall fume toxicity hazard can be weighed in conjunction with potential risks and the shifted costs for redesigning the charge formulation, without worrying about whether the requisite thermodynamic rock work was undermined (inferior).