The online sensing and sorting device that has been developed within SATURN is composed of two sorting machines.
The first sorter, called “TiTech x-tract”, is an X-ray detector and measures the absorption of x-rays for determining the atomic density. The sorter uses x-rays to separate heavy metals or thick and/or aluminium alloys from thin aluminium or plastic impurities.
The second machine, which is called “TiTech finder”, consists of an electromagnetic sensor, for the measurement of conductors such as metals, coupled with a near-infrared detector, for identifying organic materials. This sorter aims at separating the ejected mix of waste (such as plastic, paper, wood, textiles) and light aluminium matters.
This ensemble has been implemented within a full scale demonstration plant in Salzgitter (Germany).
In order to operate the two sorting machines, it is necessary to install an additional infrastructure. This infrastructure consists of five subsets that are the (i) material feeding units, (ii) extraction units, (iii) de-dusting units, (iv) maintenance areas and (v) controls and switch cabinets.
(i) Material feeding: vibration feeders are required in order to obtain a proper distribution of the particles‘ size. This step ensures that every particle is measured without any overlapping of other particles. Once the particles have been correctly separated, they are directed via conveyer belts.
(ii) Extraction units: the pressurised air which is used in the process by the two sorters is provided by a compressor.
(iii) De-dusting: the sensor-based sorters generate dust which is spread and ultimately alter the extraction units. A de-dusting system must be connected to the extraction chambers of the sorters.
(iv) Maintenance areas: these areas consist of platforms and walkways surrounding the sorters to allow the maintenance staff to solve any operational problems (e.g. clogging) that may occur.
(v) Controls and switch cabinets: they can be located next to the sorters or elsewhere. They must be protected against dust.
The main outcomes of using such a sorting technology are twofold. Firstly, it saves energy, considering that making aluminium from recycled scrap takes 95 % less energy than using raw material for instance. Secondly, it protects the environment by reducing landfilling and CO2 emissions, provided that aluminium recycling releases only 5 % of the CO2 generated when refining fresh aluminium from bauxite.
Sources : System data sheet – Deliverable 15 public report ; Saturn Layman’s report