Beyond appearances: analyzing equipment can help recyclers and their consumers go beyond appearances when sorting and melting metals.

Appearances count for a great deal in the scrap metal recycling industry. Just look at the terms used to classify ferrous scrap metal. No. 1 busheling, according to Institute for Scrap Metal Industries Inc. (ISRI) specifications, is clean steel scrap, fewer than 12 inches in any dimension, which may not include old auto body or fender stock. No. 1 bundles are described as "new black steel sheet scrap, clippings or skeleton scrap, compressed or hand bundled to charging box size and weighing not less than 75 pounds per cubic foot," while No. 2 bundles are "old black and galvanized steel sheet scrap" prepared to meet the same physical specifications.

While these physical descriptions prove helpful when selling prepared scrap to end users, they do little to describe the chemistries of the metals involved. However, analyzers enable metal recyclers and consumers to peer below the surface. A brief analysis with a hand-held metal analyzer can help recyclers to properly sort and grade metals, making their scrap more valuable.

CHOOSING A METHOD. Randy Moffat, vice president of sales and marketing for Angstrom Inc., Belleville, Mich., says recyclers should first consider capability when shopping for analyzers. "'There is not a single analyzer that will do everything that a company wants it to do," he says.

Therefore, the search for the right analyzer begins with one question: What materials do I commonly handle? The reason is that the primary methods of metal analysis--X-ray fluorescence (XRF) and optical emission spectroscopy (OES)--have strengths and weaknesses associated with high-temperature alloys and light elements. OES analyzers are more adept at analyzing aluminum alloys and carbon steels, while XRF analyzers are more proficient with high-temp alloys.

Additionally, Moffat says that shavings are difficult to analyze with OES systems, because the instrument requires a solid sample in order to perform the analysis. However, operations handling large quantities of aluminum might find OES analyzers more suitable for their facilities because the technology is more accurate at determining aluminum grades.

Both OES and XRF analyzers require preparation of the metal sample in order to obtain an accurate reading. This generally consists of removing any dirt, grease or paint that is nor representative of the sample, though most manufacturers agree that the OES method generally requires more sample preparation than the XRF method. "XRF is much more forgiving than OES," Margo Myers, director of analytical marketing for Thermo Measure Tech, Austin, a division of Thermo Electron, says.

John Patterson of Metorex Inc., Ewing, N.J., says with OES analyzers, ease of use becomes an issue as well, as these instruments are generally not as easy to operate as XRF analyzers. However, he says results from OES analysis generally tend to be more thorough than from XRF analysis.

While the lack of an "all-in-one" solution may be disappointing to some scrap metal recyclers, XRF and OES analyzers can offer portability, speed and accuracy.

With hand-held analyzers, portability remains key. Therefore, XRF analyzers incorporating X-ray tubes rather than radioisotopes can offer an advantage.

"With an X-ray tube, there are no NRC (Nuclear Regulatory Commission) licenses required, the Department of Transportation has no special requirements for shipment or transport of these X-ray tube-based units, there is no wipe test and no costly replacement and disposal of depleted radioisotopes," Mark Lessard, business development manager for Oxford Instruments, Boston, says.

Don Sackett of Innov-X Systems, Woburn, Mass., also says recyclers may want to consider getting away from devices that employ radioactive isotopes because new NRC regulations will include more frequent inspections and larger floes for lost gauges.

However, that is not to suggest that X-ray tube instruments are regulation free. "Although they are not licensed as radioactive material, all states require registration of X-ray robe-based instruments, with fees ranging from $0 to $500 per year," Tom Anderson of Niron's Bend, Ore., office, says.

In addition to offering x-ray tube systems, Niton offers an isotope-based system featuring the Infiniton isotope that is maintenance free, never needs replacement and never slows down as do the traditional cadmium 109 isotopes.

For Lewis Gordon of L. Gordon Iron & Metal, Statesville, N.C., an XRF analyzer with an X-ray tube provides ease of use that he finds appealing. "The X-ray tube is a little easier, because we don't have to deal with the licensing of the radiation source," he says.

Gordon uses his analyzer to test nickel alloy scrap that cannot be identified visually. "Speed is not critical to us. We are testing things on an as-needed basis. We are not using it for production," he says. "Accuracy is the most critical aspect of the analyzer. This one gives us the elemental makeup of whatever we test within a percent," Gordon says of the Innov-X unit L. Gordon Iron & Metal uses.

BALANCING YOUR NEEDS. Gordon uses his analyzer to distinguish between 316 and 304 stainless steel.

Gordon has his analyzer set for a 15second analysis, though he says that six seconds is generally enough time to identify the piece of metal in question.

"Speed and accuracy are directly proportional to each other. Multiply the measurement time by four, and you will cut your error in half," Myers says of XRF analyzers. "If a few tenths of a percent in an element makes a difference, then you'll take the time to measure it precisely," she adds.

"In general, the longer the analysis time, the better the accuracy," Lessard says. "Though for most alloys that scrap processors deal with, sufficient performance is achieved in less than five seconds with a portable X-ray system." He adds, "You would get an accurate alloy identification or accurate grade and accurate results for the major elements in that alloy."

Niton's Anderson adds that pinpoint accuracy is generally less important than speed at the sorting station, where the goal is to move as much material through as quickly as possible. "Generally, they might take a representative sample of the sorted material, looking at the high-value elements in order to calculate price."

Patterson also finds the balance is toward speed. "Recyclers go for as accurate a reading as they can get as quickly as possible. The analyzer that can get the best measurement the fastest is the one they will chose, assuming all other things are equal," he says.

"In OES, speed and accuracy are not such a trade off," Patterson adds.

Angstrom's Moffat says, "If you want to sort by grade, hand-held works fine in most applications." He adds that analysis can be completed in two to thee seconds using Angstrom's OES unit.

Of course, accurately identifying and sorting metals can benefit a recycler's bottom line as well as his reputation.

POCKETING THE RESULTS. "If you can ship a sorted load of material as opposed to a mixed load, you get a higher price for it," Sackett says. "The big filing is to make sure everything in that load is what they say it is to avoid that costly downgrade," he adds.

"Larger recyclers that guarantee furnace melt chemistries can be ensured that they will not pay penalties for selling out-of-spec material," Lessard says.

Gordon says using an analyzer enables his company to pay the top price for scrap metals based on a known chemistry. For example, Gordon says, customers occasionally call indicating that they have some scrap that they think is high-temp alloy. "We tell them to bring it in. We'll test it and pay them the top price for it based on what it is," Gordon says.

Moffat tells of a client who takes his OES analyzer with him when he goes to bid on scrap. The analysis influences bow he bids on material. The same customer uses his analyzer within his scrap yard to upgrade material. "If he buys a series listed [generally] as aluminum or stainless, he can separate the metals by alloy and get more money for the material," Moffat says.

"There are many alloys that you cannot distinguish by color or magnetism," Myers says. "That is how you can get a high super alloy like Hastelloy mixed up with common stainless steel. A recycler can demand more money for exotic steels, so much so that in a very short period of time, the instrument is usually paid for."

Anderson says, "If a recycler has a reputation for providing accurately sorted material, the consumer will be willing to pay more." If a recycling company goes to bid for what is presented as a load of stainless, but analyzes the material to find that it's nickel, Anderson says, "It could conceivably pay for an instrument with one load."

Scrap consumers may use handheld analyzers to verify incoming loads, though they tend to have more rigorous analysis requirements that require desktop laboratory analysis equipment. It's a question of sorting versus verification of melts, which requires much more precision.

"I find they want to do more analysis, they want to look more and more at trace-level elements. They tend to have more demanding analytical requirements," Sackett says, adding that consumers also see value in quickly verifying loads of incoming material.

Patterson of Metorex says that metal consumers generally look for tramp elements that can spoil their melt chemistries. "OES analysis can detect lower levels of tramp elements," he says.

Gordon recommends that other recyclers perform a cost-benefit analysis when considering the purchase of a handheld analyzer. He says a handheld XRF analyzer may not be a justified investment if a yard does not deal with a lot of nickel alloy items. "You can use it to test aluminum, but it may not be as effective as with nickel alloys and copper-based items. If you handle a lot of nickel alloys and brasses, it can be used to segregate your metals a little more precisely than you would be able to do without the analyzer," Gordon says.

"The best way to evaluate an analyzer is to call other scrap yards, visit them and see how they use it in the field," he adds.

TALKING ABOUT THROUGHPUT

Two manufacturers have introduced units geared toward providing analytical equipment that couples throughput with accuracy.

Daniel Pflaum of Cincinnati-based Gamma-Tech LLC is sole distributor of a bulk scrap analyzer manufactured by Thermo Gamma-Metrics, a wholly owned subsidiary of Thermo Electron, Waltham, Mass., that uses prompt gamma neutron activation analysis (PGNAA) technology.

Installed in line with a scrap processor's shredding operations, the unit enables instantaneous, composite-based analysis of scrap metal. "By putting this technology in line with the shredding operation, you could control the process and make a very tight spec product with low variability, specified to whatever the consumer is looking for," Pflaum says.

The analyzer, currently in use at River Metals Recycling, Newport, Ky., provides information on six elements--copper, nickel, chrome, manganese, titanium and zinc.

Austin AI LLC, Austin, Texas, manufactures a unit that is integrated with a hopper or trommel and uses XRF technology to analyze metal by alloy type. The analyzer recognizes 15 alloys and allocates material by type using either mechanical or air-jet diverters. Austin AI President Rick Comtois says the analyzer is designed to process one to 10 tons per hour.

The author is associate editor of Recycling Today and can be contacted via e-mail at [e-mail].