改性硝酸铵爆轰安全性研究 Ⅰ.CaCO_3和MgSO_4对硝酸铵爆轰安全性的影响

Detonation Safety of Modified Ammonium Nitrate Ⅰ.The Influences of Calcium Carbonate and Magnesium Sulfate

将碳酸钙和硫酸镁改性的硝酸铵按照工业炸药配方配制成铵油 (ANFO)炸药 ,以 8号雷管起爆 ,对硝酸铵的爆轰安全性进行了评价。采用恒温热分解和示差扫描量热法 ,研究了改性硝酸铵及铵油炸药的热分解行为。测定了改性硝酸铵的比表面积以解释爆轰结果。得出如下结论 :硝酸铵含 4 0 %的碳酸钙 ,或 2 5 %碳酸钙和 5 %硫酸镁的混合物 ,所配制的铵油炸药不能被 8号雷管起爆。碳酸钙同硝酸铵发生复分解反应放出NH3 、H2 O和CO2 气体 ,反应程度与碳酸钙的含量、温度和时间成正比。虽然硝酸铵中加入碳酸钙后提高了ANFO炸药的热稳定性 ,但由于上述气体的逸出增加了改性硝酸铵的比表面积。因此 ,在硝酸铵中加入少量的碳酸钙不能达到爆轰安全性的要求。硫酸镁与硝酸铵形成复盐 ,可减缓硝酸铵和碳酸钙之间复分解反应的速度 。

Ammonium nitrate(AN) is modified by calcium carbonate and magnesium sulfate, and then mixed with fuel oil and sawdust to make ANFO explosives. The explosives are initiated by No.8 detonator. The thermal decomposition of the modified AN and ANFO explosives have been studied by isothermal and DSC method. Specific surface area of the modified AN is determined to explain the detonation result. It is concluded that ANFO explosives can not be detonated with addition of 40% calcium carbonate or a mixture of 5% magnesium sulfate and 25% calcium carbonate. The double decomposition reaction between calcium carbonate and ammonium nitrate produces volatile gases such as NH 3, H 2O and CO 2 and the decomposition rate is proportional to the calcium carbonate content, temperature and time. Although the thermal stability of ANFO explosives could be improved by calcium carbonate, requirement of detonation safety is not met by adding low amount of calcium carbonate into ammonium nitrate because the specific surface area of the modified AN is increased greatly by the volatilization from mentioned gases. The double salt formed from magnesium sulfate and ammonium nitrate could decrease the double decomposition reaction rate and reduce the detonation sensitivity of the modified AN.