To prospect an urban mine – assessing the metal recovery potential of infrastructure “cold spots” in Norrköping, Sweden

In conventional mining, prospecting methods are used to increase the degree of certainty with regard to the stock of metals. Similarly, prospecting in terms of “urban mining” aims to increase the information about metal stocks available for recovery in the built environment. Infrastructure systems, such as for power supply and heating, are rich in copper, aluminum and iron (including steel). For a number of reasons, pipes and cables remain in the ground after being taken out of use or disconnected. This is also true for entire obsolete systems. In this paper, these infrastructures “cold spots” are viewed as hibernating stock with a significant potential for urban mining.The infrastructure systems for AC and DC power, telecommunication, town gas and district heating in the city of Norrköping, Sweden, have been quantified and spatially allocated with a GIS-based approach of Material Flow Analysis (MFA). About 20% of the total stock of aluminum and copper in these systems is found to be in hibernation. The findings also indicate that cables have been disconnected to a larger extent than pipes. As an example, cables for DC power, taken out of use in the late 1930s yet still in the ground, consist of 230 tonnes of copper. The results illustrate a clear tendency for larger stocks of hibernating copper and aluminum to be found in the central rather than the outer parts of the city. A reverse, ring-like pattern is true for iron, mostly because the central parts of the town gas pipes are used for fiber optics.Particular focus has been placed on the industrial area of Södra Butängen, which is slated for re-development and re-zoning from industrial to residential. Since the ground will be dug up for sanitation purposes anyway, the entire metal stock can be taken into prospecting consideration. Analysis shows that the chances of finding aluminum here are 28 times higher than in the rest of the city.We argue for an increased MFA focus on the heterogeneous complexity found in the details of the specific locale, rather than striving for generalized assumptions about the broader picture. In doing so, MFA could very well provide a tool for a future business line of urban mining of hibernating metal stocks.