## 2 Review of Influence of Sensitizers on Detonation Properties of Emulsion Explosives
### Chemical Density Reduction
Compared to the standardly aerated Emulinit 8L (using the EE sensitizer without the addition of sodium perchlorate), the resulting EE exhibited higher detonation velocity, brisance, and air blast parameters, lower content of harmful detonation products, and a shorter density reduction time (Table 2). Between 2013 and 2016, five studies by [PERSON] et al. [13; 14; 15; 16; 17] were published, in which the authors proposed the use of magnesium dihydride (MgH\({}_{2}\)) as a sensitizing agent for EEs. The sensitizing agent was dihydrogen microbubbles formed during MgH\({}_{2}\) decomposition. Publications [17; 18] present the results of studies on the parameters of emulsion explosives (EEs) containing matrices with a density of 1.31 g/cm\({}^{3}\). These matrices consisted of ammonium nitrate (75%), sodium nitrate (10%), paraffin wax (4%), diesel oil (1%), emulsifier (2%), and water (8%). The performance of EEs sensitized with magnesium dihydride (MgH\({}_{2}\)) (98% purity, average particle size of 3 \(\upmu\)m, and bulk density of 1.45 g/cm\({}^{3}\)) was evaluated and compared to that of EEs containing glass microspheres (GMs) (average particle size of 55 \(\upmu\)m, bulk density of 0.25 g/cm\({}^{3}\)), a GM/Al mixture, and sodium nitrite (NaNO\({}_{2}\)). The compositions and parameters of the EEs are shown in Table 3.  
The high detonation capability of EEs is due to their structure consisting of the maximum homogenization of oxidants and combustible components, ensuring the maximum degree of rearrangement in the chemical reaction zone of the detonation wave, as well as gassing additives forming \"hot spots\" in the non-explosive matrix. The shock wave propagation in the EE, which does not initiate the detonation process in the loaded material, can cause its partial or complete desensitization, as a result of emulsion reversal (crystallization of oxidants [18]) or the deformation (destruction) of hot spots. The aforementioned phenomena may occur during blasting operations as a result of the \"channel effect\". \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Component**} & \multicolumn{3}{c}{**Sensitizer**} \\ \cline{2-4}  & **EE** & **BK-1** & **BK-2** \\ \cline{2-4}  & \multicolumn{3}{c}{**Component Content [wt. \%]**} \\ \hline Ammonium nitrate & - & 30.0 & 47.1 \\ Water & 95.45 & 61.6 & 41.0 \\ Sodium perchlorate & - & 4.0 & 8.0 \\ Sodium nitrite & 4.50 & 3.0 & 3.3 \\ pH modifier & 0.05 & 1.5 & 0.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sensitizer’s components [11]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sensitizer**} & **Detonation** & **Peak Over-** & **Impulse** & **Explosive Gas Content** \\  & **Velocity** & **pressure 1** & **ABV 1** & **[kg/dm3]** \\  & **[m/s]** & **[kPa]** & **[Pa-s]** & **NO\({}_{\mathbf{x}}\)** & **CO** \\ \hline EE & 4233 & 123.73 & 57.20 & 0.55 & 4.11 \\ BK-1 & 4647 & 127.13 & 57.53 & 0.33 & 2.51 \\ BK-2 & 5033 & 131.20 & 58.60 & 0.31 & 3.45 \\ \hline \hline \end{tabular}  
* 2 m from axis of EE sample.  
\end{table} 
Table 2: Sensitized EEs parameters when sensitized according to [11; 12]. Therefore, [PERSON] et al. conducted studies of the effects of shock waves of different intensities on EEs sensitized with MgH\({}_{2}\) and, comparatively, with GMs [14,15] or sodium nitrite [15,16,17]. They placed 30 g EE samples in a container filled with water at various distances from a 10 g hexogen booster (hexogen/wax 95/5, density-1.45 g/cm\({}^{3}\)). The EE samples were subjected to the shock wave generated by the detonation of the booster. The unloaded and loaded samples were then initiated with the detonator and the overpressure course was determined using the underwater test method.