Page 54 from: May / June 2018
Buyers of all Ferrous,
Non-Ferrous Metals &
End of Life I.T. Equipment
Tel: +44 141 440 0424
Fax: +44 141 440 0874
E-mail: [email protected]
Website: www.jradam.co.uk
Riverside Berth, King George V Dock
Renfrew Road, Glasgow, G51 4SD
Buyers of all Ferrous &
N n-Ferrous Metals
The worldwide construction market is
expected to be worth over US$ 1 tril-
lion by 2020, according to research
firm Statista. Currently, upwards of
461 million tons per year of increas-
ingly complex construction and demo-
lition (C&D) waste are generated in
the EU alone, for which there is an
average recycling rate of approxi-
mately 46%.
hsi advanTages
‘considerable’
‘There are a lot of new structures and
roads in development, which will add
to the already sizeable waste flow of
the international construction and
demolition market,’ observed Roberta
Palmieri of Rome University. ‘The
good thing is that this waste is being
reused or recycled more and more.’
But of course, she added, recycled
aggregates ‘must be competitive with
natural aggregates.’
She agreed that the advantages of an
HSI-based quality control approach
are ‘considerable’, describing the
technique as ‘objective, fast and non-
destructive, allowing continuous per-
formance of a low-cost analysis’.
She and her team at Rome University
have applied this method to distinguish
recycled aggregates from contaminants
such as brick, plastic and wood, while
also separating mortar paste from
aggregate particles. An objective of this
work was to boost high-value ‘green
concrete’ production.
‘mosT probable’
Palmieri took delivery of a bulk quan-
tity of C&D waste from a nearby recy-
cling plant. At the university’s lab, she
then ran this material through a sys-
tem equipped with an HSI sensor with
a short-wave infrared range of 1000-
2500 nm in order to check the quality
of the recycling facility’s output
stream.
The investigated samples were sorted
into seven different categories, name-
ly: aggregate, brick, foam, gypsum,
mortar paste, plastic and wood. From
each of these categories, particles
were randomly selected and HSI clas-
sifications were performed based on
two different acquired sample sets,
those being the system training sam-
ple set and a validation sample set.
The training image ‘library’ contained
208 655 pixels to build the classifica-
tion model, while 84 440 pixels were
classified in the validation image. In
the first stage, materials were sorted
The worldwide construction market is expected to be worth over US$ 1 trillion by 2020.
That’s why the University of Rome is investigating how to improve the sorting efficiency
of this growing waste stream.
into ‘most probable’ categories, while
the system ‘learns’ and effectively
upgrades its sorting practices.
‘About 70% of the acquired HSI data
was used to calibrate the model and
about 30% to validate it,’ Palmieri
remarked. She added that the work
relied on the SisuCHEMA XL Chemical
Imaging workstation created by Finnish
tech company Specim. In terms of soft-
ware, Chemadaq was used to acquire
the spectra, and spectra patterns were
analysed using PLS Toolbox.
Palmieri expressed satisfaction with
the initial results of the experiments.
‘Classification was successful, with one
exception; aggregate particles were
sometimes mistaken for mortar paste,’
the researcher stated. The errors can
be attributed to light scattering
effects owing to the roughness and
heterogeneity of the particles’ surface
as well as to the ‘dirty’ nature of the
materials that were not washed in
advance.
‘greaTer qualiTy conTrol’
Therefore, a new classification model
was built to specifically target these
two material categories. ‘This time
around, the sorting accuracy was very
good for all input types,’ Palmieri
reported. As such, the method was
found to be suitable for identifying
the presence of pollutant materials in
the C&D waste stream and for
enabling ‘greater quality control’ for
recycling firms.
54
The reliable brand!
SOLUTIONS TO TRUST IN
> Static and mobile XR class: get up close to our waste wood shredder at the Biomass Preparation
Technology (VDMA) Demonstration Days
> RS150 4-shaft shredder: the power pack for extraordinary requirements
> QR class: trouble-free shredding of recyclables
> UNTHA Lifetime Support: new service packages for a long uptime and machine life
www.untha.com/ifat
NUMEROUS
INNOVATIONS
Hall B6, Stand 127/226
52-56_smartsorting.indd 54 25-04-18 08:37
