The formation of explosive compounds in bitumen/nitrate mixtures

Ignition of various bitumen/nitrate mixtures was examined using a new method of thermal analysis, developed in the present study, in order to determine the self-ignition temperatures (SIT) of the sample materials. The effects on the SIT of transition elements, particularly silver, and the heating rates were examined. The same bitumen/nitrate mixtures were prepared by mixing bitumen, NaNO(3), Ni(NO(3))(2) and either AgNO(3) or AgI. The sample heating rates were in the range from 0.5 to 4.0 degrees C/min. In the present work, SIT was found to be independent on the heating rate when AgI is added, while SIT was found to depend on the heating rate when AgNO(3) was added. The activation energy E(a) for the ignition of bitumen/nitrate mixtures has been calculated to be 30 kJ/mol. The suspected initiator of the ignition is thought to be silver fulminates or related compounds.