Inertisation of municipal solid waste incinerator ashes with electrodynamically generated, underwater shockwaves

Fresh ashes from municipal solid waste incinerators (MSWI) elute harmful chemical compounds in contact with water. Therefore, storage over a period of three months is necessary, before deposition or application as construction material. A treatment of ashes by means of electrodynamically generated underwater shockwaves improves the quality of the ashes decisively. The result is a material which is effectively fragmented into minerals and metals, ready to be separated afterwards. It is assumed that free radicals produced by means of shock waves and spark-induced plasma processes lead to chemical reactions in the ashes with a reduction of the pH-value. This processes, and washing effects reduce the elution of heavy metals to such a degree, that the ashes can be used immediately after the treatment without a storage of three months. In this sense one can talk about artificial aged ashes, which finally allows an in-time, online conversion of garbage into construction material and metal. The pulse power device used is a seven-stage Marx generator with mutual facing air-spark gaps. Each of the seven capacitors has a capacitance of 100 nF with a maximum applied voltage of 200 kV. The charging voltage of the Marx generator is reduced to 50 kV, which gives a pulse voltage in the order of 350 kV. The peak current is about 10 kA at a ringing frequency of 500 kHz. The charge-repetition-frequency is 7 Hz and the primary input-power 10 kW. All components of the fragmentation device are enclosed in a metallic cave to obtain EMP, noise- and man protection. The first destination of the device, which is called FRANKA-1 (Fragmentierungs Anlage Karlsruhe), is a pilot operation at a MSWI.