Rising prices for raw materials are slowing down the European economy, according to Peter Rem, Professor of Resources and Recycling. He demonstrates how we can extract more of our raw materials from waste.
We are addicted to metals, and the ore supplies are finite’, says Prof. Peter Rem (CEG Faculty). ‘A shortage of raw materials is going to emerge, starting in Europe. Europe was the first to begin industrial development, and it has almost no raw materials of its own remaining. European imports of energy and materials amount to €500 billion per year. This is 4% of the European economy. It had been 2%, but the prices of raw materials exploded between 2005 and 2008. We need to switch to the use of raw materials from recycling before another price increase of this magnitude occurs. The entire industrial sector will eventually need to shift, but Europe is facing the greatest urgency’.
Innovations in recycling are sorely needed. In the 1960s, the extraction of metals from waste was seen as a type of mining, and some of the same techniques were used. The results were disappointing: 40 years later, only 4% of all raw materials came from recycling. Nobody had realised that recycling, in contrast to mining, would yield an array of metals suitable for re-use only in their pure form. Moreover, economically interesting metals in waste are often in very small particles, making them difficult to extract. Separate collection and improved separation techniques are now allowing Germany to obtain 15% of its raw materials from recycling. Rem predicts that, in 15 to 20 years, we will need to recycle at least half of our metals. He is developing the technology for doing this.
Metals from ash
In 2007, the TU Delft alumnus Jaap Vandehoek approached Rem. On assignment from the metal supplier Fondel, he was searching for metal-recycling technologies. After touring Europe, his search led him back to his own faculty, where Rem and his group had recently developed a ‘neat technology with great potential’.
This technology made it possible to extract nearly
all metals out of the ash from waste incinerators –
something that had not been possible before. The ash is a sticky, burnt-out mass containing tiny small metal particles: a curtain hook, a tack, a shred of copper wire and many pellets no larger than a few millimetres. It is all stuck together with wet ash. For this reason, the fine metal particles cannot be extracted with magnets or eddy currents.
Now, seven years later, the separation technology is being used on an industrial scale. The Inashco (Incinerator Ash Company) firm, which was established with patents from TU Delft and investments from Fondel, manufactures devices that process hundreds of tons of the ash per hour. A river of ash flows from a conveyor belt to a rapidly turning turbine vane wheel. Blows from the wheel knock adherent ash away from the metal particles and shoot the material into a metal tube measuring 25 metres in length. While the lighter particles start whirling downward after only a few metres, the higher density of the heavy particles cause the heavier particles – including the majority of the metal – to fly further. The result is two separate streams, one of which now allows the use of eddy currents to extract the metal particles from the heavier portion. The majority (96%) of the input ultimately remains as a fine, metal-free mineral fraction that can be processed into curbs and paving tiles. The remaining 4% forms a concentrated stream, about half of which consists of non-ferrous metals. In this way, the Advanced Dry Recovery (ADR) unit produces an enriched stream of metals. ‘It contains aluminium, copper, zinc, lead, gold, silver, platinum and palladium’, explains Inashco director Arno La Haye. ‘You can see the entire periodic table passing by.’
Another device operates in the refinement process to separate the remaining minerals from the metals and to separate the metals into the lighter aluminium and the other, heavier metals. Inashco supplies the two mixtures as raw materials for the metal industry.
Seven years ago, the company consisted of only one man. It now processes 2.5 million tons of ash per year, with a turnover of €50 million. It employs 130 people in locations in the Netherlands, Germany, Finland, Singapore and the USA. In two years, when all of the installations that have been contracted are operational, the company will be processing 4.3 tons of ash per year, amounting to 17% of all global production.
Meanwhile at TU Delft, Rem’s group is working to develop new separation technologies. Using magnetic fluids, the researchers are already able to separate various metals into five different densities. Special sensors are offering prospects as well. Infrared ‘light’ can sometimes reveal differences between apparently identical metals.
‘We can achieve that 50% recycling’, states Rem. ‘Doing so, however, will require considerable effort to apply the principles of physics in the market’. Rem is convinced that his research deserves greater investment. It is a frequently heard argument, but Rem can back it up with a good story: ‘Research should not focus on whatever is hot right now, but on the problems that will be playing a role in 5–10 years. One of these problems is Europe’s dependence on imported raw materials’.