Summary and conclusions

Oparbejdning af metaller fra affaldsforbrændingsslagge

Up until 2005, metal packaging was not given independent priority in Danish waste planning, and nor was it made the subject of systematic collection in municipal waste models. Consequently, the majority of this type of waste was probably collected and disposed of alongside other standard domestic waste, commercial waste resembling standard refuse, and mixed bulk waste for incineration.

The Danish Government’s Waste Strategy 2005-08, which is based on the recycling objectives stated in the EU Packaging Directive, states among other things that by the end of 2008 Denmark is to recycle 50% of all its metal packaging. This objective can only be achieved if systematic measures are implemented during the years ahead, now inspired by a new stipulation in the Danish Statutory Order on Waste (Affaldsbekendtgørelsen) obliging any municipalities that do not yet have a collection system to introduce such a system for the disposal of metal packaging. This could be done as part of the current bulk waste collection schemes (often referred to as the “municipal iron system” in Danish). Systems for waste separation at source have not yet achieved 100% collection, so the separation of non-magnetic metals from incinerated bottom ashes is one way to achieve the overall recycling goal for metal packaging, while also improving the total recycling and utilisation potential of incineration residue, which represents the largest waste fraction in terms of volume (approx. 650,000 tonnes per year).

The aim of this report is to gain greater clarity regarding the amount of metal packaging on the Danish market, and to register the paths by which this packaging is disposed of, on the basis of all existing data sources. This will make it possible to utilise tests of new methods and separation technology in a reasoned assessment of the financial basis for the implementation of methods and technology. At the moment, the project has only been approved with a view to drawing up a report covering the non-magnetic metal fraction (primarily aluminium, but also zinc, copper, brass etc). Wherever possible in practice – in the data material and when carrying out test separation – data for tinplate has been included in the report so that the potential for meeting the EU’s future recycling objective can be reflected somewhat more accurately.

The current project involves investigating a new method and the use of new separation technology to process incineration bottom ashes, as well as providing an accurate prediction of the volume that can be collected in practice. Based on fresh incineration bottom ashes, the method involves processing metals down to a size of approx. 8 mm – comprising both magnetic metals (including stainless steel) and non-magnetic metals. The use of fresh incineration bottom ashes reduces oxidisation of the metals in the piles of residue, thereby optimising both the quantity and quality of the metals. The new technology, known as “detection/ejection” technology, has in fact been developed for the separation of shredder metal. In this project separation technology is used in combination with other processing equipment with a view to releasing non-ferrous metals from combustion residues.

The project has been divided into the following main points:

Assessment of the residue separation achieved, including comparison with experience gained in other countries (France and the Netherlands) and assessment of the data material in Denmark to identify the recycling potential.
Description of separation tests – results and proposals for further investigation.
Financial requirements with regard to implementing the technology at Danish incineration plants/residue operators.

The project has resulted in the following main conclusions:

The method is capable of increasing the volume of metal collected.
The method has worked with regard to processing metals from fresh bottom ashes, and has a clearly positive influence on metal quality and thus on scrap price.
Separation of the metals and the method used do not seem to have any influence on the mechanical properties of the bottom ashes in terms of their current use.
The method is deemed to have a similar effect with regard to metal fractions of less than 6-7 mm, which is expected to increase the volume recovered to a not insignificant extent.
The volume of metal packaging that can potentially be processed from the incineration bottom ashes, as shown in this investigation, seems to correspond to similar results obtained from processing in the Netherlands and France.

Which means that:

Metal processing can be carried out on commercial terms, financed by the sale of the processed metal – thereby helping to meet the future recycling goals for metal packaging.

Completion of the investigation has shown that there is still a need:

To validate the data and the basis of calculations.
To stimulate interest in investing in and developing new separation equipment – for instance by amending the Danish Statutory Order on Residues (Restproduktbekendtgørelsen), thereby placing processing requirements for non-ferrous metals on a par with current requirements for processing iron metals, with a view to stimulating the development and use of separation technology.
To create overall clarity regarding the influence and effect of various traditional political, administrative and financial methods of controlling metal packaging in the Danish waste model.