Jun 11, 2023
LIBS: the final step to lowering the carbon footprint in scrap sorting • Recycling International
‘Shortly after the pilot, the first production unit was installed in Sweden in 2019 and more followed in early 2020, although business then slowed for nearly two years because of the pandemic,’
‘Shortly after the pilot, the first production unit was installed in Sweden in 2019 and more followed in early 2020, although business then slowed for nearly two years because of the pandemic,’ Comtois recalls. But in 2022, thanks to a presence at international shows such as ISRI, IFAT, IARC and Aluminium Düsseldorf, sales records have been boosted in recent months.
‘Another lesson that we learned when meeting aluminium experts at the shows is that, although the value of our LIBS sensor sorters is known, these experts are reluctant to add costs. This is despite our advertising showing a fully loaded cost of under two cents per pound processed.’
Let’s deal with the basics first. It is known that chemical composition is a key characteristic of aluminium products. Regarding the laboratory routine, spark optical emission spectrometry (EN14726) is the dedicated standard method for determining accurately the chemical composition of aluminium and its alloys.
LIBS is an analogous analytical chemistry method offering better precision and accuracy with lighter elements. Because of its laser-based generated signal, it is also easier to implement into the industrial process design.
‘At this juncture, there is no surprise that with Austin AI’s LIBS sensor sorter one can achieve such a low detection limit as being able to pull a specific alloy, such as 6063,’ says Austin AI’s founder. ‘Moreover, we have proved to a client an application where 6063 A2/A3/A4 are separated.’
Creating the sortation programme for 6063, one can not only set a single alloying element but all eight are possible together with their related, or any desired, concentration level.
These could be:
With the help of such a unique feature, users can be confident about purity of above 95% in an extracted fraction that can be directed to smelters with no additional blending. It is truly a green way to avert primary aluminium consumption by adjusting scrap composition before it is loaded into a smelter.
Austin AI is often asked by recyclers: ‘Do we need X-ray Transmission (XRT) or X-ray Fluorescence (XRF) if we run a LIBS sensor sorter?’ XRT, XRF and LIBS technology-based sensor sorters have their own unique applications and advantages. So the answer depends on the material what recyclers want to sort. For Zorba, for example, XRT is an ideal, fast and efficient technique to start with.
XRT sorters are just like medical X-rays: sortation is based on a physical parameter, namely the density differences. Although, LIBS works well, XRT is the best way to separate ‘lights’ from ‘heavies’. Further steps to gain distinguished groups from heavies can be done by XRF or LIBS.
LIBS is a great choice when sortation begins with the ‘lights’ infeed, especially if silicon content is an issue and/or magnesium-based alloys are of interest. The specialty of Austin AI LIBS is that, starting with either wrought or cast aluminium main groups, the sorter can provide alloy specific sortation of both groups.
Low concentration differences are well detected. Cu and Fe (<0.1%) cast aluminium alloys are already working applications.
Aerospace and car industry tend to dominate with more and more lightweight magnesiumbased alloys and we are receiving more requests for magnesium-based alloy sortation. This is another one of the key applications we traditionally have been able to perform.
Here is a brief overview of the advantages of a worldwide patented Austin AI LIBS sensor sorter:
Additionally, the laser used for the excitation process is fully solid state and of a class used for metal cutting. At a rep rate of 50 000 Hz, the system is capable of ‘burning’ through most painted, oxidised, and otherwise contaminated scrap material.
The proprietary, industrial spectrometer is designed for high performance in terms of alloys sorting. Achieving sub-class alloys sorting at reasonable purities and efficiencies is possible. All of this, says Comtois, delivers an ‘outstanding analytical performance’.
‘With our high performance, newly developed Gen#2 LIBS modules we can sort most of the critical alloying elements with a threshold as low as 0.1%.’
The flagship model is the six-lane/six-sensor design, offering high capacity and high-efficiency alloy specific scrap sorting for secondary smelters and the recycling industry. A new, single lane LIBS-based sensor sorting system is ideal for R&D purposes and/or low capacity needs.
The LIBS technology-based WheelSorter system can assess large car parts, such as wheels, with a throughput capacity of >10 TPH. No shredder processing is required.
‘Across the entire aluminium industry, investing in recycling has currently become the preferred initiative to reduced carbon emissions in the smelting process,’ Comtois underlines. ‘When you are aiming towards carbon neutrality, sustainability, green aluminium production, etc. consider Austin AI innovative LIBS technology as the final key.’
And he adds: ‘Truly, only melt the alloy you want to cast. It saves fuel and increases furnace turns per day. Given a fully loaded cost of under two cents a pound, it’s a true winner.’
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