Can Re-Use of Demil Explosives and Propellants in Commercial Blasting Be Made Environmentally Acceptable

摘要

Some modern commercial blasting agents such as ANFO are of an oxygen balanced composition, i.e. their composition is such that there is just enough oxygen (mostly from ammonium nitrate) to oxidize all the hydrogen in the composition to water, all the carbon to carbon dioxide, and any aluminum to alumina, Al2O3. Such blasting agents in ideal detonation give a minimum of polluting and toxic reaction product gases, such as CO, NO, NO2, NH3, and CH4, to mention a few. When blasting agents are used in large (6 - 13 inch diameter) drillholes in blasting with heavy overburdens of rock, there is generally enough time for the chemical reactions to reach equilibrium while the pressure is still high. This results in a very complete and clean combustion, closely resembling that of an ideal detonation. A condition for clean bum is that the fuel and oxidizing ingredients are intimately mixed. Many commercial emulsion and slurry explosives are not oxygen balanced - most contain more fuel in the form of hydrocarbon oils, fuel oil, mineral oil, and emulsifiers, which are also hydrocarbons. When the composition is not oxygen balanced, either positive or negative (an explosive with a positive oxygen balance has more oxygen, one with a negative oxygen balance has less oxygen than the oxygen balanced composition), then the production of toxic and polluting gases increases rapidly. When explosives with a positive oxygen balance detonate, large quantities of NO and NO2 are formed; when explosives with a negative oxygen balance detonate, large quantities of CO, H2, NH3, CH4, and other gases are formed, the larger quantities the larger the deviation is from oxygen balance.