Physical Sciences Incorporated (PSI) successfully executed a Limited Scope program to design, develop, and demonstrate a multi-cycled, closed-loop, environmental friendly, chemical (CLEC) process to demilitarize three classes of pyrotechnic-smoke formulations: (1) Obscurant Grenades, (2) Riot Control Grenades, and (3) Signal (Obscurant or colored smoke) Grenades. More information on the three types of conventional pyrotechnic-smoke compositions is below:

  1. Obscurant grenade: 46.8 % wt. Hexachloroethane (HC)/46.8 % wt. zinc oxide (ZnO)/6.4 % wt. aluminum (Al);
  2. Riot control grenades: 35% wt. 2-chlorobenzalmalononitrile (CS)/30% wt. potassium chlorate (KClO3)/10% wt. magnesium carbonate (MgCO3)/25% wt. Sugar; and
  3. Signal (obscurant) grenades: 35% wt. Red-Dye/30% wt. KClO3/10 % wt. MgCO3/25% wt. Sugar.

Technical Approach

The CLEC demilitarization Process-A focused on recovering HC and ZnO, the processing byproduct aluminum oxide (Al2O3), sodium hydroxide (NaOH)/water (H2O) and methanol (MeOH) solvents from HC based obscurant grenades. Process-B focused on recovering CS or red-dye from the pyrotechnic kit ingredients from riot control and signal grenades, and regenerating the N-methyl-2-pyrrolidone (NMP) and water solvents.


Process-A’s objective was achieved with HC being recovered in 81% yield and the ZnO and Al2O3 being recovered in 62% yield with an 83% purity. For Process-B, the recovery of each additive was achieved at greater than 85% for each additive, and 67% for the pyrotechnic kit. For both processes, all solvents were recovered and used in subsequent cycles of the demilitarization process.


The CLEC demilitarization process successfully recovered all components from the pyrotechnic-smoke compositions for commercial resale, as well as all solvents for recycling. The CLEC process eliminated the environmental footprint of hazardous materials while simultaneously maximizing the reduction in operational costs.