‍Introduction

Aluminium is the most abundant and environmentally friendly metal on earth. Quite often referred to as the “Green” metal, aluminium is sustainable, capable of being recycled and reused without loss of its inherent properties. Aluminium recycling is one of the most efficient forms of recycling, using up 95 percent less energy than creating aluminium materials from virgin materials (primary production). Globally, aluminium demand is up while primary production is down resulting in recycled aluminium expected to help fill in the gap. Primary aluminium producers are creating new products that have substantial amounts of recycled aluminium driven in part by the high energy costs to create primary aluminium, consumer demand for more environmentally friendly products and corporate sustainability goals.

In aluminium recycling, Zorba is a term used for a mixed scrap of non-ferrous metals that contains aluminium, copper, and zinc, among other materials. Twitch is produced by a method of sorting Zorba stock. This method involves sorting scrap aluminium into different grades, lights and heavies. Once sorted, Twitch (lights) can be sold off to an aluminium producer to create new alloys for production or re-processing.

This article details the justification and implementation of a fast, effective sorting system developed by Austin AI utilizing Ocean Optics’ LIBS sensor with H Ripley and Co, Ltd, a large recycler in the UK.

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Photo: Aluminium Scrap Yard/Green recycling symbol

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The Problem

Fast, cost-effective sorting of Zorba has long been a desire for scrap recyclers. H Ripley and Co, based in Hailsham, UK, has been a fifth-generation family-owned scrap yard in business for over 100 years.  Like many yards, they have dealt in ferrous and non-ferrous scrap since their inception. However, unlike most other yards, they have also been shredding aluminium for over 30 years. 

Jason Ripley, commercial director with H Ripley and Co realized a long time ago that there was significant value that could be extracted from aluminium if the right tool existed. His company was selling mixed aluminium that contained multiple premium grades as a fast, cost-effective sorting tool was not available to separate the grades and alloys, and hand sorting was not an option. Jason mentions, “The concept and need has been there all along. There just was not the right technology to sort aluminium quickly and effectively.”  The significant uptick in aluminium demand further drove this need over the past decade. 

H Ripley and Co, like other scrap recyclers, is a user of handheld XRF and was aware of on-line X-ray solutions. While a good option for heavy metal sorting, X-ray does not lend itself well to sorting aluminium. Jason was introduced to an Austin, Texas based company named Austin AI by his customer, Hydro Aluminium. Hydro had success with Austin AI’s solution and urged Jason to investigate it further. 

Sensor Sorting Technology

Rick Comtois, CEO for Austin based Austin AI, is a veteran of elemental analysis and has been focused on on-line sensor sorting technology for over 20 years. Having previously implemented numerous units based on both Nuclear Magnetic Resonance (NMR) and X-Ray Fluorescence (XRF) technology, Rick began to shift his focus to Laser Induced Breakdown Spectroscopy (LIBS) in 2014. Rick says that LIBS technology offers unparalleled light element technology that is not feasible with other methods. 

His company’s interest in light element sorting solutions led to a relationship with Hydro Aluminium in which Austin AI built a sorting system for pulling out Aluminium 6063 from construction and demolition (C+D) material. The result of this process for Hydro Aluminium and any secondary smelter is melt ready “green material” allowing them a much-desired lower carbon footprint. 

Austin AI’s LIBS sorting system offers the following advantage:

• Reliable, robust modular design with minimal moving parts
• Flexible setup with either 1 or 6 lanes
  
  • 6 lane design allows for a LIBS module to be internally replaced to maintain uptime.
• Chute design where sample drops in front of the LIBS laser.
  
  • No need to adjust focal distance per sample.
• Works with clean production scrap as well as post-consumer scrap with no pre ablation needed.
• Lowest fully loaded cost per weight ratio in the world
• Compatibility with Ocean Optics’ SpeedSorter LIBS sensor.

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Photo: Austin AI LIBS Sensor Sorter

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Online sorting provides significant advantages over manual sorting, including increased speed, accuracy, consistency, and efficiency. It also reduces labor costs, increases safety, and provides valuable data for optimizing aluminium sorting. 

Rick states, “I estimate the fully loaded cost which includes Initial cost of the sensor; the operation cost; labor cost, etc. to be a few cents per kilogram when running our sorter at 4-5 tons/hour. This cost is outweighed by the premium gained per truckload for melt ready scrap.”

As demand for sorting technology increased, especially in Europe, Austin AI established a service center in Budapest and is proud of the support and training they can provide Europe based customers like H Ripley. 

What is LIBS?

Laser induced breakdown spectroscopy (LIBS) is a form of atomic emission spectroscopy using an energetic laser pulse highly focused at the sample surface to convert a small mass of a sample to plasma, causing the atoms and ions to emit their characteristic emission lines. For many, LIBS is recognized as optical emission spectroscopy (OES) that uses a laser instead of an arc or spark source. LIBS has been known and used for almost two five decades in laboratory and research environments.

Recent technological advancements have made the design of on-line LIBS sensors, like the SpeedSorter from Ocean Optics, possible and available for use in industrial applications. This development rapidly expanded the use of LIBS especially into field operations such as aluminium sorting and analysis.

Since LIBS is better suited for analysis of light elements such as lithium (Li), aluminium (Al), magnesium (Mg), and beryllium (Be) than handheld X-ray fluorescence (XRF), it is quickly gaining industry acceptance as a method of choice for sorting specific alloys from aluminium scrap.

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Photo: LIBS Diagram

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SpeedSorter

Ocean Optics’ SpeedSorter is an industrial, high-throughput sensing system designed for in-line, nonferrous scrap sorting in difficult environments. Based on LIBS, the SpeedSorter quickly determines the chemical composition of each aluminium scrap object and communicates the result to Austin AI’s sensor system. With the SpeedSorter, separation of wrought from cast aluminium, aluminium from magnesium and alloy class separation like 6XXX from Zorba are easily accomplished. 

The SpeedSorter can be customized to the exact needs with consideration of conveyor capabilities, input material and size, and desired output and diversion control.

“Insert Ocean quote”

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Photo: SpeedSorter  

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H Ripley and Co.’s Implementation of On-line LIBS Sensor Technology 

H Ripley set off to implement Austin AI’s Sensor Sorter late in early 2020. The project goal was to implement a solution for retrieving a steady stream of 6063 from mixed Aluminium Zorba. Working closely with both Austin AI and Ocean Insight, Ripley integrated the LIBS Sensor Sorter for the sorting of shredded, clean, dry material in process post magnetic and Eddy Current separation. 

Prior to the implementation, Ripley processed and primarily sold mixed aluminium to markets in Asia. Post implementation of the sorting sensor, Ripley is segregating and selling back the valuable portion to the primary producer, in this case to Hydro Aluminium.

Hydro Aluminium has been pleased with the 6063 received from Ripley that is within their specified tolerance and standard. Copper and Zinc removal is key for Hydro Aluminium looking for material that is below the 0.1% max allowable amount of each. Lower, in this case, is always better. The following is the Alloy 6063 specification for Hydro Aluminium:

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Element Spécifications

Si 0.2-0.6%

Fe Max 0.35%

Cu Max 0.10%

Zn Max 0.10%

Mg 0.45-0.9%

Cr Max 0.10%

Mn Max 0.10%

Others 0.05%/each (Max 0.15%)

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Photo:  Screenshot from SpeedSorter of 6063?

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Hydro Aluminium has been extremely satisfied with their material and Ripley’s LIBS sorter has provided them with a “worry-free,” low carbon footprint stream of Low Cu and Zn 6063 material.   

Covid-19 related delays as well as other unforeseen delays have meant that the LIBS Sorting Sensor has only been in use for the past three plus months. Jason Ripley goes on to say that “Austin AI, Ocean Applied and Ripley had a common goal of getting this project over the finish line so he had no doubt that the unit would be up and running and working effectively for us as soon as possible.”  

Through the first three plus months, Ripley has been running 3-4 tons of material per hour through the sorting sensor.  As noted by Rick Comtois and Jason Ripley, material should be dry as material flows/travels better when it is not wet. Size can vary but 5-6 inches is considered mid-range and best for higher throughput. Additional screening within the process will further assist with the purity of the resulting material obtained. 

Path Forward

Jason Ripley is proud to see the LIBS Sensor Sorters implemented at his facility. He knew for decades that the need was there, and that the technology would eventually be available to make it happen. 

As can often be the case for early adopters, Ripley and Co. is finding that the industry is not aware of LIBS nor that this sort of sensor technology exists. This has made expanding their customer base more challenging than initially thought. Jason Ripley mentioned going as far as to sponsor a trial load of LIBS segregated material for new clients for them to fully grasp the capability the technology has. Austin AI’s Sensor Sorters with integrated SpeedSorter does offer clients like Ripley the ability to change sorting programs to allow for segregating whatever alloy and tolerance is needed. This will allow them to add customers more easily with specific application requirements. 

Ongoing installation of the Sorting Sensor at other yards that process one hundred plus tons per day will help with adoption as will further adoption of handheld LIBS based systems which are growing in popularity for light element analysis within the scrap industry.  

Conclusion

Austin AI’s and Ocean Optics are pleased to offer the aluminium industry a rapid and effective solution for recovering melt ready scrap. Their Sorting Sensor facilitates efficient recycling, conserves resources, reduces energy consumption and emissions and promotes the transition to a circular economy which all collectively contribute to a greener environment.