When cars are recycled, it is very difficult to recycle the material from the residual waste that arises. Car furnishings are an example of such material. A completely new solution is to be tested in a full-scale project.
"When the waste is incinerated together with the digested sludge that comes from what we flush down the toilet, we hope to get round the problem and extract large quantities of energy, which were previously lost", says Christer Forsgren, Head of Technology and Environmental Science at Stena Metall.
At Stena´s shredder plants, large quantities of waste are recycled every year. Cars, machinery and other complex metal waste in the community are ground into fist-sized pieces. The material is then sorted and returned as raw material to produce new products. One challenge is that about 20 percent of a scrapped car's weight cannot be recycled in an effective way. It is important to overcome this challenge, in order to meet future European legislation on waste and to reduce the volume of landfill. Car fittings, which contain leather, rubber, textiles and mats, are examples of waste where the materials cannot be recycled.
"The residual waste from the operations is complicated as it contains, among other things, zinc and lead that, together with chlorine, can form corrosive gases that damage the incinerator furnace", says Christer Forsgren.
"The idea for this project is to see if the residual waste can be incinerated together with household waste and digested sludge from sewage works. With the sulfur, and the digested sludge's other beneficial characteristics, it is hoped that it will be possible to avoid the build up of damaging deposits in the incinerator boiler."
If the residual waste can be used to produce energy by incineration, it also means significant environmental advantages.
"If we can utilize all the energy from our residual waste in an incinerator, we can use the energy for district heating or electricity production. The energy is equivalent to heating about 10,000 houses for a whole year," says Christer Forsgren.
Stena Metall is running a full-scale Waste Refinery project jointly with Metso Power, Statens Provningsanstalt, HTC at Chalmers, Lidköping Energi as well as Borås Energi och Miljö. The residual waste will be incinerated in the trial at an incineration plant in Lidköping in Sweden.
"This is hopefully the first step towards a complete solution for handling problem waste. If things turn out well, it could lead to a future solution for waste that the industry today cannot recycle", says Christer Forsgren.