Hazardous or toxic waste destruction or containment – Containment – Solidification – vitrification – or cementation
Patent
1995-08-16
1997-07-15
Jones, Deborah
Hazardous or toxic waste destruction or containment
Containment
Solidification, vitrification, or cementation
A62D 300
Patent
active
056485913
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for the treatment of toxic materials and relates more particularly, though not exclusively, to a process for the treatment of halogenated organic compounds such as poly-chlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane (DDT), monochlorobenzene and chemical weapons such as Sarin and mustard.
BACKGROUND TO THE INVENTION
There is today increased public awareness and improved scientific understanding of the hazards to health and the environment of many synthetically produced chemicals, insecticides, herbicides and other toxic materials. Of particular concern due to their high toxicity and persistence are halogenated organic compounds such as PCBs, Dioxin, DDT, monochlorobenzene, dichlorophenol, pentachlorphenol, Dieldrin, Aldrin, 2,4-D, 2,4,5-T, and other compounds such as Paraquat, Diquat, Phorate, Bromicide, carbamates and Atrazine. There is therefore a need for effective methods of disposing of such toxic materials. The wide spread use of PCBs as dielectric fluid additives in transformers and other electrical equipment, due to their excellent insulating properties, present a particularly serious disposal problem.
In some countries stockpiles of chemical weapons, which include organophosphorus nerve agents and mustards, await a suitable means of disposal. This disposal is required under the terms of the Chemical Weapons Convention of 1993. The disposal of such materials presents a particularly severe problem, since accidental dispersal could result in enormous loss of life. A disposal system with extremely low risk factors is required for this application. A deadline for weapon destruction of Dec. 31, 2004 has been set by the Chemical Weapons Convention.
Currently proposed methods of disposing of toxic materials typically involve high temperature incineration, biochemical or chemical treatment. High temperature incineration seeks to destroy toxic waste materials by converting them to gaseous products. Any toxic gases, such as hydrogen chloride, must then be removed from the effluent gas before it is released to the atmosphere. If operating conditions are not closely controlled, there is a possibility that toxic materials will be released into the environment either through incomplete destruction of the original materials or through creation of new materials in the incinerator or through inefficient gas cleaning. Control systems are required to regulate the fuel addition, air flow, temperature, flame, gas composition, scrubbing liquor flow and so on. Back-up systems to deal with loss of electrical power are also required. These systems comprise a very large number of individual components, both electrical and mechanical, and the failure of any one of them may lead to the immediate loss of integrity of the system as a whole. Failure of the system could lead to widespread dissemination of toxic material into the surrounding environment.
Chemical treatment results in chemical decomposition of the toxic materials through the action of suitable reagent mixtures. U.S. Pat. No. 5,064,526 to Rogers et al discloses a method for both the decomposition and removal of halogenated and non-halogenated organic compounds contained in a contaminated medium by the use of an alkali or alkaline earth carbonate or bicarbonate or hydroxide, a hydrogen donor such as an oil and a catalytic form of carbon such as a carbohydrate. This process is conducted at elevated temperatures, requiring the application of heating and cooling systems, fire prevention systems, power failure systems and gas emission systems. These systems comprise a multiplicity of components and interconnections, each of which is the subject of possible failure, and the malfunction of anyone of them may lead to a loss of the integrity of the system as a whole. In the event of a failure leading to a fire, there is potential for widespread dissemination of toxic material into the surrounding environment.
Processes involving the use of baths of molten metal or salt, plasma arcs or other
REFERENCES:
patent: 4345983 (1982-08-01), Wan
patent: 4666696 (1987-05-01), Schultz
patent: 5053142 (1991-10-01), Sorenson et al.
patent: 5064526 (1991-11-01), Rogers et al.
Patent Abstracts of Japan, C-77, p. 2762, JP,A,52-78855 (Shimazu Seisakusho K.K.) 7 Feb. 1977 (Jul. 02, 1977).
Patent Abstracts of Japan, C-78, p. 1819, JP,A,53-64667 (Sumitomo Denki Kogyo K.K.) 6 Sep. 1978 (Jun. 9, 1978).
PCT International Search Report for International Application No. PCT/AU 93/00660.
Donecker Peter
McCormick Paul Gerard
Rowlands Sally-Anne
Street Robert
Harding Amy M.
Jones Deborah
University of Western Australia
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