Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Patent
1995-07-24
1996-11-12
Suchfield, George A.
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
588256, 588260, 405128, B09B 300
Patent
active
055742041
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for the mutual chemical treatment and compaction of inorganic waste materials intended for disposal by deposition, in which the waste materials are in loose form and are compacted by applying high pressures.
BACKGROUND OF THE INVENTION
In prior art methods for the chemical treatment and compaction of inorganic waste materials high quantities of water are added and high quantities of binder are required. In such methods the reaction mixture usually has the consistency of a pumpable mixture. Due to the use of the high quantities of additives these methods have the disadvantage of a large increase in the volume of waste.
One prior art method for the physical treatment and compaction of inorganic waste materials comprises compacting the waste under pressure. The inorganic waste materials are mixed with each other in accordance with appropriate specifications and compressed at high pressures to form solid compacts. Due to the low permeability of the slabs their elutability is reduced. These waste slabs are transported to the disposal site and placed in the disposal unit in modular form. Although this method has the advantage over the abovementioned methods of saving space in the disposal unit the compacts are not dimensionally stable under water and their constituents can be reeluted after prolonged exposure to water.
The prior art is further described in the following literature references
Literature
immobilising soil contamination") Chem.-Ing.-Tech., 59, 1987, 393 Chem.-Ing.-Tech., 56, 1984, 55 Mullverbrennungsanlage ("The compaction of residues from a refuse incineration plant in Luxembourg") VGB Kraftwerkstechnick, 69, 1989, 1132 disposal of residuals from power stations") Techn. Mitt., 78, 1985, 58 and Zement ("The fixation of heavy metals in secondary materials by compaction with cement") Beton 38, 1988, 193-198 E.; Pozzolanic Fixing Agents J. Hazard. Mat., 24, 1990, 145 Hazard. Mat., 24, 1990, 157 Bayer Kompakt-Deponie ("The high-pressure compaction and deposition of waste materials, as part of the system employed in the Bayer Compact Disposal Process") Chem.-Ing.-Tech., 63, 1991, 605 Schlammuntersuchung Schlamm und Sedimente (Gruppe S) DIN 38 414
Based on the above prior art a method has been developed in which the advantages of the abovementioned methods of chemical treatment and compaction are combined with those of the abovementioned physical treatment methods.
SUMMARY OF THE INVENTION
The new method is characterised according to the invention in that various water-containing inorganic waste materials intended for disposal by deposition, which contain water-soluble components capable of reacting chemically with one another, are mixed together and compacted under such a high pressure that the pore volume of the loose material mixture is reduced essentially to the liquid volume resulting from the moisture in the loose material of the waste mixture, so that the pores between the particles of loose material are filled completely or almost completely with liquid. As a result, chemical reactions take place between the reactive components dissolved in the liquid phases of the components of the mixture and the reactive constituents contained in the particles of loose material, as a result of which the toxic substances contained in the waste materials are completely or partially converted into materials which are less damaging to the environment by precipitation, neutralisation and redox reactions.
In one variant of the method according to the invention the toxic substances are converted into sparingly soluble compounds during the conversion process and are thereby immobilised.
According to a further development the pressure required for the complete filling of the pores is determined by measuring the onset of dehydration during compaction and the compactor is controlled with the aid of this measured signal.
The compacting pressure is advantageously in the range from 20 bars to 5,000 bars, and preferably in the range from 80 bars to 400 bars.
The residual moisture of
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Bauer Gerd
Beyer Joachim
Koglin Bernd
Menzel Thomas
Rink Rolf
Bayer Aktiengesellschaft
Suchfield George A.
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