Several documents deal with processing of rocket propellant for the purpose of ammonium perchlorate recycling.
The patent U.S. Pat. No. 4,854,982 uses liquid ammonia for the processing. The presence of liquid ammonia (required to maintain a high pressure and the toxicity of ammonia) represents a disadvantage of this method, along with a low capacity of the technology related to a unit of investment costs.
However, most patents use leaching of ammonium perchlorate into an aqueous solution as the principal basic part of the processing.
The patent U.S. Pat. No. 3,451,789 gradually processes propellant by disintegration, leaching of ammonium perchlorate into a hot aqueous solution followed by multiple-stage separation of the solid residue after leaching from the obtained solution.
The patent U.S. Pat. No. 4,662,893 deals with the construction of a leaching unit.
A disadvantage of the two above mentioned patents is the problem of formation of agglomerates of solid residues of the propellant during disintegration, leaching and separation from the solution, which results in high energy and construction demands and a reduction of efficiency of the recycling process.
The patent U.S. Pat. No. 4,198,209 addresses this problem by adding surfactants (surface active agents). A disadvantage of this treatment is contamination of the obtained ammonium perchlorate solution by a foreign substance and formation of foam causing technological problems during further processing.
This problem is addressed in the U.S. patents U.S. Pat. No. 4,198,209 to Frosch et al.: “Process for the leaching of AP from propellant” (1980); U.S. Pat. No. 3,451,789 to McIntosh: “Oxidizer recovery process” (1969); U.S. Pat. No. 4,662,893 to McIntosh: “Hydraulic waste propellant macerator and method of use” (1997); U.S. Pat. No. 4,854,982 to Melvin et al.: “Method to dimilitarize extract, and recover ammonium perchlorate from composite propellants using liquid ammonia” (1989); and U.S. Pat. No. 4,098,627 to Tompa et al.: “Solvolyptic Degradation of Pyrotechnic Materials Containing Crosslinked Polymers” (1978).