Material Recovery of the Glassy Slag Produced from Asbestos Containing Waste
Abstract
The present article deals with the option of high-temperature processing of asbestos-cement roof tiles in a plasma reactor. It describes the process of melting this type of waste in a plasma reactor which is aimed at obtaining the resulting product in the form of vitreous slag of the inert nature. The article also briefly comments on the potential recovery of the formed slag which may be used as the secondary material for further manufacture processes.
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Introduction
Converting materials into material values and increasing their life standard are associated with many problems which affect, to various extents, the natural environment and consequently also humans. One of the apparent human interventions in the natural environment is the production of waste and the persisting existence thereof in the environment. It may be assumed that the amount of waste will grow and this will also increase the number of problems regarding the waste disposal. This means that most waste types, categorised depending on their characteristics and environmental hazard, will have to be recycled in future, not only because of the potential to recover certain desired components (e.g., metals), or because of their energy potential, but mainly because of the environmental protection [3].
A special waste category is the hazardous waste which includes the asbestos-containing waste. The disposal of this kind of waste must be paid special attention as this waste possesses hazardous properties.
At present, the disposal of asbestos-containing waste is divided into seven waste disposal categories. In terms of the environmental protection, important disposal methods are the methods categorised under numbers 01 to 03, i.e., material recovery, energy recovery, and other. The percentage of the recovered hazardous waste is still insignificant due to its hazardous properties.
The removal of asbestos materials from buildings is subjected to the permit issued by the Public Health Authority of the Slovak Republic pursuant to Act No 355/2007 Coll. on the Protection, Support and Development of Public Health. The yearly production of asbestos-containing waste in the period from 2010 to 2015 is shown in Fig. 1 [1].
Conclusion
The comprehensive evaluation of the waste management level in the Slovak Republic indicates that the waste disposal is the segment that has been neglected for a long period of time, as to the technology level and the development the market relationships, and nowadays this segment experiences dynamic development. Novel legislation and the incorporation of the European regulations into the laws of the Slovak Republic created the fundamental regulatory and control conditions for further development of this segment.
In terms of the environmental protection, the purpose of the manufacturing segment is to produce products which may be used as the sources of secondary materials or energy after being decommissioned. Achieving this goal, especially in the segment of manufacture and processing of the products possessing hazardous properties, is often difficult. A potential solution for the recovery of waste containing asbestos fibres is to remelt it applying the high-temperature melting process. In addition to obtaining the inert slag, the resulting slag may be used as the secondary material after slightly modifying its composition. The production of ceramic material will result in the product which may be regarded as 100% recyclable after its service life elapses. In addition to this factor, another advantage is that even the hazardous waste, i.e., asbestos-cement roof tiles, will be recovered and disposed of.