Asbestos: Disposal, And Recycling.
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Introduction:
“Asbestos” is a group of minerals that occur naturally as bundles of fibers, which can be separated into thin threads. These fibers are not affected by heat or chemicals and do not conduct electricity. For these reasons, asbestos has been widely used in many industries. Four types of asbestos have been used commercially since:
Chrysotile, or white asbestos: also known as cement-bonded or hard-bonded asbestos.This is the form most commonly found in the home. It contains asbestos fibres in a cement base and was used on garage roofs and sometimes garage walls as well as the iron stand on an ironing board. It can also be found in some warm air heating systems and storage heaters.
Crocidolite, or blue asbestos: also known as unbonded, fibrous asbestos. These are the most dangerous forms associated with human disease s and are sometimes found in older buildings as insulation, pipe lagging, ceiling tiles and internal walls and panels.
Amosite, which usually has brown fibers.
Anthophyllite, which usually has gray fibers.
Asbestos was mined and used commercially in North America beginning in the late 1800s. Its use increased greatly during World War II. Since then, it has been used in many industries. The shipbuilding industry has used asbestos to insulate boilers, steam pipes, and hot water pipes. The automotive industry uses asbestos in vehicle and clutch pads. More than 5,000 products contain or have contained asbestos.
Based on the results of a number of health studies, it is recognized that asbestos can endanger human health. The inhalation of asbestos fibers in high concentrations is known to cause a unbearable and irreversible respiratory illness. Exposure to asbestos may increase the risk of several serious diseases:
Asbestosis–a chronic lung ailment that can produce shortness of breath, coughing, and permanent lung damage.
Lung cancer.
Mesothelioma–a relatively rare cancer of the thin membranes that line the chest and abdomen; and
Other cancers, such as those of the larynx, oropharynx, gastrointestinal tract, and kidney.
The latency period associated with these diseases can involve several decades. Because inhalation is the exposure route of concern, it is important to prevent asbestos fibers from becoming airborne, being directly contacted.
Asbestos is regulated as both a solid waste and a hazardous air pollutant. It must be disposed in a manner that will prevent fibers from becoming airborne. At present, the most cost effective method of disposal is by burial. Although this generally means the removal, transportation, and off-site land filling of materials, there are certain instances where asbestos was used as a fill material and the sites are closed by covering the material in place.
Keep in mind that undisturbed asbestos containing materials are generally not considered hazardous. It is only when the material begins to deteriorate or becomes disturbed (for example, by careless removal or uncover of land filing) that asbestos fiber could be released into the air and thus become hazardous to anyone breathing in that environment.
The current disposal technique is to seal the asbestos containing materials (ACM) and adhering metal (pipe, framework, duct work) in plastic for safe transportation to a burial site. Burial of wrapped asbestos covered pipe and/or ductwork necessitates large disposal volumes in regulated disposal sites, e.g. landfills and burial grounds, and expensive removal operations. The availability of regulated disposal sites for ACM has become problematic and expensive.
What I want to show in this paper is the new technologies in recycling the ACM, to gain a changing the asbestos from hazardous to non-hazardous materials, and reusing the ACM.
A new technology solution to the disposal and recycling of hazardous asbestos:
Safe disposal of ACM at U.S. Department of Energy (DOE) sites, likewise, requires large disposal volumes in landfills for non-radioactive ACM and large disposal volumes in radioactive burial grounds for radioactive and suspect contaminated ACM. The availability of regulated disposal sites is rapidly diminishing causing recycle to be a more attractive option.
Technologies have been developed by the private sector and the U.S. Department of Energys (DOE) Savannah River Site (SRS) to convert hazardous ACM to a non-hazardous amorphous non-crystalline solid (NCS), glass. Conversion to an NCS eliminates the ACM and fiberglass inhalation hazards which can lead to silicosis and/or asbestosis of the human lung and ultimate death.
Asbestos adhering to metal (e.g., pipes) can be recycled by safely removing the asbestos from the metal in a patented hot caustic bath, which prevents airborne contamination/inhalation of asbestos fibers. The dissolution residue (caustic and asbestos) can be wet slurry fed to a melter and vitrified into a glass or glass-ceramic.
Palex glasses are very tolerant of the high MgO and high CaO content of the fillers used in forming asbestos coverings for pipes and found in boiler lashing, e.g. hydromagnesite (3MgCO3*Mg(OH)2*3H2O) and plaster of paris, gypsum (CaSO4). The high temperate of the vitrification process destroys the asbestos fibers and renders the asbestos non-hazardous, e.g. a glass or glass-ceramic. In this manner the glass or glass-ceramic produced can be recycled, e.g., glassphalt or glasscrete, as can the clean metal pipe or metal framework.
It is well known that treatment is more costly ($330/ton for a 100 ton per day) than the current “wrap in plastic and bury” disposal methodologies ($110/ton) for non-radioactive asbestos. However, treatment eliminates the continuing liability associated with disposal of non-radioactive asbestos-containing wastes in landfills and offers the opportunity for some profit of the recycle material as aggregate in roadways (glassphalt or glasphalt) or in construction (glasscrete) and recycle of the adhering metal. Therefore, an in depth cost evaluation must consider a value added factor for the additional benefits of recycling.
Asbestos Recycling, Inc. (ARI):
The venture brings to market a self-contained, transportable system known as the Asbestos Conversion Unit (ACU) to accomplish the complete thermochemical conversion of all asbestos waste forms. ARIs exclusive patented system converts asbestos fibers into harmless minerals of a non-toxic and non-fibrous form. And it achieves this at a price comparable to