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Linköping: first to test mining operations
Will it pay to excavate copper cables from the ground under Linköping? The answer will be clear in a couple of years. Joakim Krook and his research group are conducting a demonstration project to test two different technologies.
“The studies we conducted in Norrköping were completely theoretical; now we’re practically testing the conditions of using a city as a mine. It’s also a way of validating our results from Norrköping,” says Krook, research lead for the projects in Urban and Landfill Mining.
Two different technologies will be tested in Linköping: normal digging on the one hand, where the entire length of the cables is excavated, and another using an Austrian technology called Kable-X.
In short, it is based on digging a hole at either end and spraying organic oil between the sheath and the tape that holds the cable’s core together. When the oil is pushed in, the friction is reduced so it becomes possible with a winch to draw out the copper core.
“This technology works for, and has been used on, electric cables, but it’s never been tested before on power cables,” Krook says.
The clever thing about this technology is that, in the same operation where the copper core is drawn out, fibres can be blown in from the other end of the pipe left underground, something that could be interesting for Tekniska Verken’s net company, Utsikt Nät.
However a lot of work is to be done before the project reaches that point.
“We’re starting by mapping what’s underground here in Linköping, both connected and disconnected. We’re also going to study what the future looks like, how quickly the disconnected supply changes,” Krook says.
The Kable-X technology will also be tested on the surface, and workers from Utsikt Nät will be trained.
“We have to see how we can solve the practical problems, what happens when the cables are spliced, for example,” he says.
One problem is also that they don’t always know where the splices are; this is an issue for cables laid in the 1960s and 1970s, which were not always so well documented.
Digging in a city is both expensive and complicated, so it’s also a question of taking the opportunity when excavation is undertaken for other purposes.
“Each year in Linköping alone, between 400 and 500 excavation jobs are undertaken. There should also be better cooperation between the municipality, the pipe owners, and recycling companies; they’re the ones with the knowledge of which would be profitable to excavate,” Krook states.
“During 2013, a Formas-funded demonstration project called Economic and Environmental Evaluation of Metal Recovery from Disconnected City Power Grids will be ready. Then, to start with, we’ll get an answer as to which technical, economical, and especially environmental conditions we’ll be able to use for Linköping as a copper mine.”
Monica Westman Svenselius 17-01-2012
Photo: Peter Modin
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Last updated: Mon Sep 03 13:49:03 CEST 2012
