Page 26 from: Recycling International May/June issue 2023

The world’s first automated LIBS-based sensor
sorter for used wheels
‘The first production car using an

aluminium unibody had an

impressive 500 pounds (227 kg)

weight savings over steel

construction,’ observes Rick

Comtois, ceo of Austin AI.

Since that time aluminium has

become a dominant material of the

car industry.

Car wheels are a significant part of the total
weight of aluminium-dominant cars.
Historically, they have been made from iron,
magnesium, and wrought aluminium alloys.
However, the number one constituent in auto-
motive wheels is now a cast aluminium-based
material. Such wheels can vary in silicon con-
tent from 5% up to 15%.

VERY QUICK ANALYSIS
‘This variation makes the recycling process
expensive as the addition of, or dilution using
lower concentration of, silicon additives
requires a lot of incremental furnace time,’
Comtois explains.
AAI’s automated patented laser sensor-sorter

using induced breakdown spectroscopy (LIBS)
has solved this issue. LIBS technology is well
documented and it has the capabilities of
other outer-shell electron spectroscopy such as
arc/spark which are commonly used to certify
or advise on the quality of any melt. Several
key advantages of LIBS are: non-contacting;
very quick analysis time; and a full range of
major/minor trace elements.
If presented whole, used car wheels are best
sorted by alloy type, so hand-held devices
such as LIBS and XRF guns are commonly
used. ‘Even in the best of cases, the wheels
need some pre-treatment for cleaning the ana-
lytical surface and this takes seconds per anal-
ysis,’ Comtois says. ‘It is possible to run up to

two wheels per minute in this manner optimal-
ly yielding 1.5 tonnes per hour, per person.’
The AAI system automatically cleans, tests,
and determines whether the wheel is to be
passed or rejected based on its chemistry. This
can be done, including a residue reduction
phase (abrasive cleaner), to easily yield about
10 times the throughput with no human inter-
face. Sorted in this way, used wheels are capa-
ble of directly entering the shredder followed
by secondary furnace in-feed.

‘FAR SUPERIOR’
LIBS is powerful analytical tool and the technolo-
gy is far superior to other sorting techniques
such as X-ray (transmission or fluorescence) or
colour sorting when considering sensitivity and
timing. The sorting process can be quite strin-
gent. For example, one of AAI’s users has
requirements beyond the silicon content, such as
very low iron (+/-0.15%) and copper (+/-0.10%).
‘When you imagine the wheels are moving for
most applications using LIBS, this is a very
impressive statement with regard to the latest
advancement of the art,’ according to Comtois.

‘The saving in fuel consumption per tonne of
output is a major saving by itself,’ he adds.
Labour, turnaround time, and tonnage
throughput all dramatically feed to the bottom
line of the secondary smelter. ‘In addition, this
generates a significant green impact to the
smelter’s operations. It truly is this last point
that reflects upon the sustainable nature for
any secondary processor.’

The AAI LIBS-based wheelsorter system automati-
cally cleans, tests, and determines the whole car
wheel to pass or be rejected.

The first car using aluminium unibody had an impressive 500 pounds weight savings over steel
construction.

VISIT US:
@ BIR Amsterdam, 22-24 May, Stand #S8
Where we can provide more details about
Austin AI LIBS sensor sorting technology in
more details.

26-27_austinai.indd 26 03-05-2023 16:53