A great many of the different plastics in end-of-life products cannot currently be recycled. Through a Vinnova research project, in which Boliden and Stena's recycling companies participated, it is no longer necessary to incinerate these plastics or send them to landfill sites. Instead, they can be used as resources in smelting processes and replacements for virgin fossil fuels such as coal. At the same time, material recycling is increased.
In Sweden, 300,000 tonnes of plastic is discarded each year that it is not economically viable to recycle. This is due to the complexity of its composition and the different types of material that contaminate it from a material recycling perspective. Some of it is production waste or comes from discarded electronic products and cables. Most of the material can be energy recycled, although some of it is deposited on landfill sites, in the absence of other solutions.
- This is a major challenge. Sustainable solutions must be found to recycle as much plastic as possible, says Marianne Gyllenhammar, a project manager at Stena's Research and Development Department.
Recently, Vinnova - the Swedish Agency for Innovation Systems - funded research that tested an alternative solution. Boliden, a metal production company that uses energy-intensive processes, took part in the project. Plastics were tested as reducing agents, and as replacements for coke, in the process of recycling zinc from slag at the plant in Rönnskär.
This technique worked extremely well in full scale testing. It means that problematic plastics, that might have been deposited on landfill sites, can provide energy and replace fossil fuels, such as coke, and act as reducing agents in smelting processes. The method also makes it possible to recycle metals that are mixed with the plastic and which otherwise would be lost to landfill deposition or combustion.
It’s a win-win situation for all parties in the chain, from manufacturers and consumers to recyclers and businesses like Boliden. Manufacturers and recyclers can move material up the waste hierarchy, while Boliden can reduce its consumption of fossil fuels by using a more climate-friendly alternative. The potential benefits are very significant. If Boliden invests in this technique, it will reduce its coke consumption by over 10,000 tonnes in each smelting furnace.