Gunning for quality

Analyzing the chemistry of inbound material has long been beneficial for buyers of scrap metal, with different aluminum, stainless and red metal alloys yielding different prices on the market.

Methods of identification and analysis have evolved over the course of several decades, but one of the bigger leaps came about in the 1990s when hand-held portable analyzer “guns” started becoming more widely available (and affordable) to scrap recyclers

For an overview of how this type of equipment has evolved and where it currently stands, Recycling Today has interviewed industry veteran Don Sackett, the co-founder and CEO of United States-based SciAps Inc.

Recycling Today (RT): Why were the first metals analyzing “guns” created back in the mid- and late 1990s, and what equipment or processes could they replace?

Don Sackett (DS): There were two semiportable “guns” available in the mid -1980s through the late 1990s. One was made by Texas Nuclear (TN) and the other by Metorex (a Finnish company). Prior to these “guns” scrap processors used a number of techniques to sort material at a very basic level. The simplest was the grinding wheel. Stainless steel, nickel alloys and titanium alloys, for example, all emit different color light and shape of sparks when hit with a grinding wheel.

Some recyclers used magnets, knowing that some alloys like a Monel (nickel-copper alloy) slightly pull on a magnet, or stainless, which doesn’t in comparison to a ferrous material. Also, there was a device called the “foos,” where you turned a handle rapidly, looked through an optic, and by viewing the different color spectral lines, could determine the likely alloy type. All of these techniques required either a very knowledgeable operator, or they only sorted crudely by alloy type (e.g., a titanium alloy versus a copper alloy, etc.).

When the first spectrometers came out, like the TN and Metorex analyzers, operators could then sort by grade as opposed to just alloy type. For example, they could determine if the alloy was a titanium 6-4 or 6-6-2 or 6-2-4-2 instead of just a titanium grade. The same goes for the wide variety of nickel and nickel/copper superalloys. Thus, this generation of “guns” allowed recyclers to sort alloys much more specifically, faster, allowing them to sell the sorted product at higher prices. Also, unlike the older techniques, many more operators could become proficient at using these analyzers faster, eliminating the purely “tribal knowledge” approach to metal sorting.

I have not yet mentioned the mobile arc/spark spectrometers. These devices also were available in the early ‘90s, perhaps earlier. They were not hand-held and required a high degree of operator knowledge to get good sorting results, but these OES (optical emission spectroscopy) devices were also highly selective alloy sorters. Also, unlike the XRF (X-ray fluorescence) units (TN and Metorex) the spark units were much better on aluminum alloys, and the lighter elements (magnesium, silicon, aluminum, phosphorus, sulfur) in general. And, they did not use a radioactive isotope as their excitation, also an advantage.

RT: Which metals were targeted initially for portable analysis? What upgrades to hand-held analyzers have been the focus of R&D subsequently?

DS: XRF portable analysis excels at measuring transition and heavy metals, including titanium, chromium, manganese, nickel, cobalt, niobium, tungsten, etc. These metals and related alloys also tend to be the higher priced material for resale after sorting. Thus, the hand-held XRF units in the 1990s and 2000s initially targeted stainless and high-temp alloys and some red metals. They did this because the technique is ideal for these types of elements/alloys (still is) and because these alloys commanded higher prices than aluminum or ferrous.

There were three major upgrades to the handhelds during the past 20 years. The first upgrade occurred around 2002, when two companies (InnovX and Niton, now Olympus and Thermo Fisher respectively) replaced the radioactive isotope with a miniature X-ray tube. The X-ray tube had two significant advantages over the radioactive source. First, it wasn’t radioactive, so the regulatory requirements were far less stringent both in costs and paperwork headaches, especially post 9/11 when everyone feared dirty bombs. The second was that the X-ray tube could excite a wider range of elements. In the old isotope XRF units, you needed three different radioactive sources to see the full range of elements from titanium to bismuth. The X-ray tube could output X-rays that could excite all these elements.

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