Acing the chemistry test

Pure aluminum may be an element of its own on the periodic table, but the auto components, factory stampings, building products and other forms of aluminum scrap handled by recyclers consist of a wide assortment of alloyed materials.

Prompt scrap, straight from the factory, tends to have a higher value in part because it is likely to consist of the same aluminum alloy in each collected bin. Finding a proper home for such material can be more easily accomplished.

But the scrap coming across peddler scales and flowing out of auto shredder downstream systems faces one or more sorting steps, providing technology vendors with an opportunity to help recyclers widen their profit margins.

Initial analysis

Bench-top and handheld analyzers have long been an important companion to nonferrous scrap buyers, whether to put the proper value on some incoming scrap or to ensure it is directed to the correct section of the facility with like alloys.

On its website, Hitachi High-Tech Analytical Science (which includes the former Oxford Instruments Industrial Analysis division), says among its family of handheld analyzers, “For aluminum [alloy identification], the Vulcan Expert, using LIBS (laser-induced breakdown spectroscopy) technology), is the best choice, as this handheld has been calibrated for the task.”

Hitachi says in 2017, a start-up scrap facility near Oulu, Finland, called Romuta “wanted to use the latest data management technology that would enable the storing of [analyzer] results, including photos, in the cloud.”

A team from Hitachi High-Tech and local distributor Finfocus visited Romuta to demo a Vulcan model. According to Jyrki Mutanen, managing director of Romuta, Vulcan “felt like a quality second-generation analyzer that is well built and robust.” As one of the fastest analyzers on the market, in one second Vulcan was able to reliably identify scrap metals around the yard one piece after another, according to Hitachi.

In a four-page document on identifying aluminum scrap alloys, United States-based Thermo Scientific (which includes the Niton brand) states, “The addition of scrap into the aluminum production line represents a major challenge for the industry and creates a considerable opportunity for handheld X-ray fluorescence (XRF).”

Each of the technologies has found a home in the scrap industry relative to aluminum identification. Regarding XRF, Thermo Scientific writes, “Aerospace alloy grades, such as 2014, 2024, 7055, and 7449, have been designed for specific functions that are not interchangeable,” and that “handheld XRF analyzers can easily [identify and] separate these grades.”

The company points to another example, stating, “Alloys 6061 and 6063 are some of the most popular aluminum alloys, used in a wide variety of applications, including the construction and automotive industries. Considering the price differential of these alloys, one could easily see the profit potential in properly segregating these alloys when processing several thousand pounds of mixed material.”

Japan-based Olympus Corp. is another provider of analyzers offering XRF options. The company says its DELTA analyzer line, which includes a Scrap Handheld model, has a “range of light alloy [identification] capabilities [that] continues to expand.” The firm says the DELTA line’s “outstanding magnesium sensitivity enables [recyclers] to confidently sort aluminum alloys once relegated to OES (optical emission spectrometry) systems.”

LIBS analysis and identification technology also has found its way to the scrap yard. Japan-based Rigaku Corp. points to its United States customer Sullivan Metals as having “discovered LIBS technology” in 2015, when it began using a Rigaku KT-100 model for aluminum and light element analysis.

A case study prepared by Rigaku Corp. quotes Brian Powell, a vice president with Sullivan Metals, as saying, “We have been very impressed with Rigaku’s LIBS capabilities of separating 6061 alloys from 5052, which can be very difficult to process so quickly.”

Sullivan says what it calls rapid and trustworthy identification “allowed us to sort specific alloys out so we’re not making a mixed package.” That, in turn, allowed Sullivan Metals to upgrade the way it prepared aluminum alloyed material and thus increase its profitability.

Technology firm Bruker describes handheld LIBS analysis as an “emerging” technology that “shows promising capabilities for alloy analysis, especially in alloys containing low atomic number elements,” including aluminum, magnesium, lithium, silicon and beryllium.

The company says its EOS 500 HH-LIBS model provides analysis of such light alloy metals in from three to five seconds, based on “laser excitation of a metal sample, followed by quantitative analysis of the light generated in the [resulting] plume.”

Bulking up

Beyond determining specific alloys and chemistries from one sample piece, recyclers and technology providers also are pursuing automated solutions that can identify and separate aluminum scrap in bulk, based on its chemistry.

United States-based TSI ChemLogix, which also offers handheld analyzers, has recently introduced its ChemLine automatic scrap sorting system, designed to sort magnesium from aluminum; wrought aluminum from cast aluminum; or 5000 series aluminum alloys from 6000 series alloys.

The company displayed its ChemLine Aluminum Scrap Sorting System at the ISRI2018 convention in Las Vegas in April (hosted by the Institute of Scrap Recycling Industries).

TSI says its patented in-line process uses a LIBS sensor to sort aluminum alloys at a rate of up to five tons per hour, including the sorting of downstream aluminum pieces from auto shredders. The firm says its LIBS sensors are able to analyze the elemental concentration of each scrap piece by measuring copper, iron, magnesium, silicon, manganese and zinc levels.

“Sorting occurs based on the actual concentrations” of those elements, says the firm. “The system’s high-speed, high-powered laser burns through contamination and coatings and is the only LIBS sorting system on the market that processes five tons per hour of shredded metal,” states TSI.

“Previously, LIBS technology had shown promise in research applications as a potential tool for automatic scrap metal sorting; TSI has turned that promise into a reality,” says Todd Hardwick, global marketing manager at TSI ChemLogix. “With an industrial sorting system based on the ChemLine sensor, this new LIBS reality will allow customers to sort aluminum alloys automatically. This advancement will benefit the scrap industry, as they adapt to the large increase in aluminum usage that is occurring in the automotive and aerospace markets today.”

TSI is not alone in developing products to help recyclers identify and sort their aluminum scrap at the bulk level. Norway-based Tomra, whose Tomra Sorting Solutions business unit is based in Germany and which has sales and distribution channels in North America, also is deploying LIBS technology on the aluminum automated sorting front.

In a presentation for the October 2017 Tomra Leads event, held in Koblenz, Germany, the company’s Frank van de Winkel noted that eddy current sensors, heavy media separation and X-ray technology had all moved automated metals sorting forward, but said LIBS was the next step needed to “detect different aluminum alloys down to the aluminum wrought alloy groups (1000 and 2000 series), and perhaps even to separate single alloys.”

Van de Winkel said in a static laser system, material needs to have a clean surface and be presented in clear view (with no overlapping) before it can be laser-analyzed and ejected for sorting. However, in a dynamic laser system being developed by Tomra, a combination of three-dimensional object analysis and dynamic (moving) laser scanning can allow material to be introduced “randomly” at a pace of three meters (9.8 feet) per second.

Tomra foresees applications in separating not only the 1000 and 2000 series wrought alloy groups, but also in separating 5000 series from 6000 series alloys, making “bulk sorting of material possible” with no need to present a single line of unobstructed pieces to the system.

Germany-based Steinert introduced an automated aluminum scrap sorting system in 2016. The company’s LSS (laser sorting system) uses LIBS technology in a manner that has the auto body panel stamping process in mind.

Steinert Business Development Manager Karl Hoffmann said at the time of the LSS’s introduction it was “targeted at companies that process new scrap or production [scrap] from aluminum stamping facilities—at companies that need to separate 5000 and 6000 series alloys, so that recycled aluminum can be used [at] the same stages of the value-creation process.”

Erie, Pennsylvania-based Eriez is working with the University of Utah and the U.S. Department of Defense (Advanced Research Projects Agency) on its aluminum sorting R&D. That combined research has led to electrodynamic sorting (EDX) technology designed “to rapidly sort scrap metal for recycling.”

According to the research partners, the EDX technology “is similar to traditional eddy current separators in that it uses time-varying magnetic fields to sort scrap, but instead of mechanically rotating a fixed drum of permeant magnets, EDX uses a fixed array of stationary electromagnets.” A write-up on the ARBA website continues, “Without the limitation of moving parts, it can achieve far higher frequencies of magnetic excitation and recover far smaller particles of scrap metal.”

EDX testing has shown it can sort nonferrous metals by both conductivity and density in a way that is “expected to be cost-effective to operate, with operating costs as low as $1.00 to $2.00 per ton for energy and labor.” In 2017, the University of Utah team spun-out a new company, EDX Magnetics LLC, to commercialize the technology.

Research being conducted by technology vendors around the world is likely to continue to change the way recyclers handle and sort their aluminum scrap, with new products likely at each succeeding ISRI convention.