Germany still extracts large volumes of building materials from quarries and gravel pits. But the country is densely populated, and the willingness of the population to accept the negative environmental impact of mining and excavations has diminished rapidly in recent decades. Creative ways will be required in future for Germany to handle the expected bottlenecks in raw materials supply and costly imports. Urban mining will be part of such a strategy since there is great potential to be tapped from the raw materials which our cities harbour in disused buildings, factories and consumer products. However, this potential is hardly being used by society. The German Environment Agency is calling for sustainable, more intensive use of these raw material reserves and seeks to create more attractive general conditions to achieve this aim.
Urban Mining refers to the use not of only inner city deposits but of the entire stock of long-lived goods in general. These goods include consumer products like electrical and electronic devices as well as infrastructures, buildings, and landfills. We are surrounded by a man-made warehouse which currently contains more than 50 billion tonnes of materials and is expected to continue to grow by another ten tonnes per capita every year.
In view of the increasing international competition for scarce natural resources, the use of secondary raw materials from domestic sources can help to conserve Earth’s natural resources and thereby secure the life support systems of today’s and future generations. Precious and special metals such as platinum, silver, cobalt and neodymium which are critical in supply are of particular relevance in this context since many future technologies depend on the availability of such metals to be functional. Furthermore, using and processing secondary raw materials in Germany has economic advantages – for the manufacturing industry which can save costs for materials, and the economy as a whole as a result of increasing domestic value added. The recycling industry is already a driver of innovation and source of employment which holds great potential.
The majority of potential raw material exists in the form rock, gravel, cement and soil in buildings. Nearly everybody has seen the disused industrial parks with buildings left behind or vacant residential buildings which dot rural regions in economic decline. By making better use and re-use of these resources it would be possible to prevent the opening of new quarries or gravel pits.
The greatest financial value is in disused metals such as the iron girders, steel reinforcements or copper wiring in empty building or bridges, or in the steel tracks of former railway lines. The scrap metal which used to be disposed to landfills is also valuable. Depending on prices for scrap, this potential has already been put to use in the past to manufacture new metal materials.
The German Environment Agency sees special potential in the upcoming years in the following areas:
- Recycled rock: Valuable, quality-assured secondary building materials could be manufactured if construction debris is already disposed according to type at the demolition site and if an integrated approach is taken to the process of recovery, processing, treatment and re-use of secondary materials in production.
- WEEE: More effective recovery of precious and special metals from durable consumer goods like mobile phones and other electrical and electronic devices can diminish dependence on expensive imports of critical supply raw materials. In addition, increased reprocessing of materials in Germany could help to end the appalling work conditions in which WEEE is handled worldwide.
- Material register: Higher recycling rates are often prevented by a lack of knowledge about the occurrence of secondary raw materials. In future, new buildings and consumer products could be issued a “material pass” which enables improved recycling. This is of particular relevance with regard to complex composites which require sophisticated sorting, separation and recycling technologies and is already a great challenge facing waste management. The stock of materials which lies dormant in certain deposits could be exploited through active collection and registration of the materials they contain.