Without accurate analysis, scrap metal recyclers may have to downgrade incorrectly identified material. And if recycling operations sell scrap to manufacturers that is incorrectly classified, the finished manufactured product may not meet customer specifications and with additional quality control shortfalls, even jeopardize the integrity of the finished product. Customer dissatisfaction, brand reputation, lost revenue, and even safety are at stake. That’s why it is important to correctly analyze and identify the metals and alloys in the scrap.
These issues have been recently discussed at the International Wrought Copper Council (IWCC) meeting. According to the USGS, “Old (post-consumer) scrap, converted to refined metal, alloys, and other forms, provided an estimated 160,000 tons of copper in 2022, and an estimated 670,000 tons of copper was recovered from new (manufacturing) scrap derived from fabricating operations. Of the total copper recovered from scrap, brass and wire-rod mills accounted for approximately 85%; smelters, refiners, and ingot makers, 10%; and chemical plants, foundries, and miscellaneous manufacturers, 5%. Copper recovered from scrap contributed 32% of the U.S. copper supply.”
With all that copper scrap opportunity, it’s crucial to accurately and quickly identify, separate, and sort the metals.
X-ray fluorescence spectroscopy (XRF) is a non-destructive analytical technique used to determine the elemental composition of materials and is a preferred method for scrap metal sorting. Handheld XRF analyzers work by measuring the fluorescent (or secondary) X-rays emitted from a sample when excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, or “unique fingerprints”. These “fingerprints” are distinct for each element, making handheld XRF analysis an excellent tool for quantitative and qualitative measurements.
One of the main strengths of handheld XRF analyzers is being able to measure accurately the composition of copper alloys within a few seconds, and identify the alloy grade. (This is an advantage to scrap metal recyclers as it makes manual sorting of items made of copper and its alloys much easier and faster.)
To illustrate these capabilities, we have shown below eight examples of common copper alloys analyzed with a handheld XRF analyzer. No analysis was longer than three seconds. Among the analyzed alloys there are a variety of wrought and cast alloys including cartridge brass, C260, free cutting brass C360, Naval Brass c464, C544 phosphorous bronze, c630 aluminum bronze which is a wrought alloy grade equivalent to C955 aluminum bronze cast grade. We have also analyzed C715 cupronickel, C836 leaded red brass and C937 leaded tin bronze.
Handheld XRF analyzers can also be used to perform “pass fail” analysis, for example to screen for regulated elements such as lead in brass and copper plumbing, which is restricted in California Proposition 65 to a maximum 0.2%. “Proposition 65 requires businesses to provide warnings to Californians about significant exposures to chemicals that cause cancer, birth defects or other reproductive harm. These chemicals can be in the products that Californians purchase, in their homes or workplaces, or that are released into the environment. By requiring that this information be provided, Proposition 65 enables Californians to make informed decisions about their exposures to these chemicals. Proposition 65 also prohibits California businesses from knowingly discharging significant amounts of listed chemicals into sources of drinking water.”
As an example, when analyzing red brass valves, if the lead concentration is found to be below 0.2%, the analyzer will indicate the metal has ‘passed.’ Another similar valve, but alloyed with different metals, could be analyzed and if the measurement shows a lead concentration over 0.2% it would show as a ‘fail.’
Such analysis can also be done for compliance screening of heavy metals related to restriction of hazardous substances (RoHS) regulations, the US Consumer Protection Safety Improvement Act, packaging directives, and other regulations.
When the exact chemical composition of copper or other metal scrap—including the existence of contaminants or hazardous elements—is uncertain, quality, safety, and regulatory compliance are at risk. XRF technology can bring accurate sorting and grading to the scrap recycling operation and help ensure product integrity.
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In our recycling facility, we used to spend countless hours manually sorting different copper alloys, which often led to delays and decreased productivity. However, after implementing the innovative methods suggested in the article, we experienced a significant improvement in our operations. The use of advanced technology, such as X-ray fluorescence analyzers and spectrometers, made the separation process faster and more accurate, resulting in higher-quality copper alloys for resale. Moreover, the article’s emphasis on employee training and safety measures struck a chord with me. Properly trained staff members were more confident in identifying copper alloys, reducing the risk of errors and potential accidents during the separation process. By adopting the techniques and recommendations outlined in the article, our recycling facility was able to optimize our copper recycling operations, maximize profits, and minimize waste. The newfound efficiency not only benefited the company but also positively impacted our commitment to environmental sustainability.Overall, I wholeheartedly recommend this article to anyone in the scrap metal recycling industry. It offers valuable insights and practical tips to rapidly and accurately separate copper alloys, ultimately leading to enhanced productivity, reduced costs, and a more environmentally friendly approach to metal recycling.