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A model showing a gold-plated mirror like those used in the asbestos melting device is seen on the right, and a container holding asbestos that was melted and then solidified is seen second from left in this photo taken at AIST in Tsukuba, Ibaraki Prefecture, on May 18. (Mainichi)

Portable technology for melting down dangerous asbestos has been invented, it has been announced.

The use of inhalable asbestos is now prohibited, but it still exists in the walls and ceilings of old buildings, where it was used for reasons such as fire- and sound-proofing. Currently, workers engaged in dismantling or repairs wrap asbestos in two layers of bags to prevent the fibers from spreading and send it either to be buried in landfills or melted down at disposal facilities. Problems include limits to landfill space, a shortage of capacity at melting facilities, and the costs of transport.

The new technology, invented jointly by the National Institute of Advanced Industrial Science and Technology (AIST) and construction company Taisei Corp., would allow workers to dispose of asbestos fibers by melting them down on-site.

The melting device used in proving the technology used a halogen lamp capable of emitting large amounts of infrared rays, which was set inside a chamber of oval-shaped mirrors plated with gold. After asbestos that has been pulverized and reshaped into a rod form is inserted, it is subjected to the focused light of the lamp. The asbestos is heated to temperatures of around 1,500 degrees Celsius, and its edges liquefy, drip down and solidify. After checking the solid with an electron microscope and other means, the researchers confirmed that the asbestos fibers had disappeared.

The entire set of equipment consists of four units, including those for pulverizing the asbestos and making it into rod-form. Lined up, the units fit into a space of 9.5 by 7.5 meters, small enough to allow them to be transported to the sites of structure dismantling or repair work.

AIST and Taisei Corp. will move toward application of the technology by seeking recognition of the technology's effectiveness from the Ministry of the Environment.