Scrap metal rises from its ashes
80 to 85% of the components of our automobile vehicles currently get recycled. But, with a European directive insisting on it, the objective of 95% has been fixed for 2015. And any extra percentage gain demands significant R&D work. It is to nibble away at these few essential percentage points that the PHOENIX project came into being within the framework of the Marshall Plan. It links up the Comet Traitments business company, a European leader in the treatment and recycling of waste metals, with several Walloon technological actors, including the University of Liège’s GeMMe Laboratory (Mineral Engineering, Materials and Environment). Within it a totally new bio-metallurgy treatment process for the very fine residues left over after grinding (less than 1mm of particle size) has been developed within the programme. With, in the bargain, new possibilities of refining recycling and creating new sectors of waste valorisation. A Walloon first!
The metallic waste (vehicles no longer in use, electrical and electronic appliances, scrap metal, etc.) treatment and valorisation sector generates constantly rising quantities of waste produced by grinding, of which around 10 million tons in Europe could be subject to further recycling through the development of alternative methods. The recycling and valorisation of these ‘material deposits’ has become a considerable issue...and a promising economic sector, inscribed within sustainable development. The public authorities have understood this very well and are now insisting on ambitious objectives which require technological innovations.
In Wallonia the efforts made over several years by Comet Traitements has enabled the company to reach above average recycling levels than its international competitors. But to stay ahead of the game, and to reach European demands, it has, along with its partners, integrated the PHOENIX project within the framework of the Marshall Plan (6.5 million Euros over 3 years). One of the innovations has been designed and developed at the ULg’s GeMMe Laboratory.
The unusual procession of metals present in these fine concentrates which arise from the residues of grinding (copper, zinc, lead, silver and gold) does not enable, given the metallurgic sectors in existence today, high recuperation levels to be achieved for each of these metals. Moreover, the energy balances of these sectors for this type of products are disappointing. ‘The innovative process we have developed within the context of the PHOENIX programme overcomes these disadvantages,’ explains David Bastin, an engineer who oversees the GeMMe Laboratory project. It concerns a bio-metallurgical leaching process, which consists of treating the flow of residues within a bioreactor. Within it the different metal composites are extracted selectively through the catalytic effect of an oxidising solution generated by micro-organisms.
A prototype of the bioreactor has been installed in the Faculty of Applied Sciences. It was presented to the press this June 15, 2012. Each day it treats in a continuous flow 4kg of grinding residue. The results are encouraging,’ adds David Bastin. The process leads to the production of electrolytic copper and zinc of high purity with concentrates denser than lead. ‘It also consists of a low temperature process which does not consume a lot of energy,’ specifies David Bastin.
The success of the pilot-unit has already had a follow-up. In 2013, thanks to European funding through the Ecoinnovation Biolix project, a first industrial unit for treating the residues of grinding, based on the process validated at the ULg, will be installed at the new Comet Traitements industrial site at Obourg. This investment, which ensures that the business company has Belgian and European leadership, will also be expressed by the creation of dozens of jobs.
As for the ULg’s GeMMe Laboratory, it has already turned towards another future: recycling methods for special technological metals such as gallium and indium, which today make up the composition of photovoltaic panels. The first panels should be recycled in 10 to 20 years. It is now that it is necessary to consider recuperation processes of these rare elements, present within nature in trace form.
Provided by University de Liege
