US EPA

3580463 

Journal Article 

Environmentally compatible utilization of asbestos cement products 

Sprung, S; Hoenig, V; Schneider, C; Gajewski, S 

1998 

51 

10 

527-+ 

WOS:000077275500003 

A total of about 30 million tonnes of asbestos cement building materials were produced in Germany between 1950 and 1991. Over 20 million t of this will still need to be disposed of during the coming years up to 2030. Because of the quantities involved it is necessary to develop an environmentally safe, industrially feasible disposal scheme which is as economical as possible. A disposal scheme, which is based on the thermal treatment of dismantled asbestos cement components in a pilot roller kiln without any preceding mechanical comminution, was investigated as part of a research project supported by the AiF (Federation of Industrial Research Associations) with funds from the Federal Ministry for Economic Affairs. There have not yet been any burning trials on an industrial scale nor any testing of alternative processes for thermal treatment in conveyor or tunnel kilns. Asbestos cement products which have been dismantled and held in a moist state in intermediate storage can be dried: thermally or with the aid of microwaves. Thermal treatment in a kiln plant was used for complete destruction of the asbestos fibres. The operation of roller; conveyor or tunnel kilns can be adapted to suit the nature and degree of weathering of the dismantled asbestos cement components through the heating rate and residence time. The temperature required for complete destruction of the fibres is about 1 000 degrees C. The secondary hardening properties of the burnt belite-rich asbestos cement products would, in principle, allow the burnt asbestos cement products to be utilized as an interground addition in Portland-cement-based binders. To be set against this, however is the inadequate soundness which means that as a whole it is not possible to reach the performance of standardized cements. Burnt asbestos cement products cannot be utilized as independent binders. On the other hand the use of the burnt asbestos cement products in raw meal for burning Portland cement clinker is an industrially feasible route for disposal. This requires a CaO-correction to match the proportion used, and the quantity used is limited by the MgO content of the clinker.