In this article, we have a conversation with Olympus X-ray fluorescence (XRF) and X-ray diffraction (XRD) expert Vladimir Vermus to discuss the role of XRF in the recovery process and understand how the advanced features of the portable Vanta XRF are analyzed The instrument meets the challenge of recycling catalytic converters.

Catalytic converters, also known as car cats, are devices that reduce the emission of pollutants from car exhaust into the atmosphere. These converters are cylindrical structures with an internal honeycomb structure that have a catalytic layer formed of platinum group metals (PGM)-platinum (Pt), palladium (Pd) and rhodium (Rh)-which are deposited On the surface (Figure 1).

When unburned waste gas residues such as carbon monoxide (CO), hydrocarbons (CH) or nitrogen oxides (NOx) contact the surface of the catalytic layer, they are oxidized and neutralized by oxygen in the exhaust gas. However, since platinum group metals are precious metals, they are valuable, which makes the recovery of catalytic converters a practical and economical way to achieve clean air.

"The typical lifespan of a car cat is about 100,000 kilometers (62,000 miles)," said Vladimir Vermus. However, if the correct processing and analysis procedures are used, platinum group metals can gain a second or even third life and be recycled into a new converter. 40% of new catalytic converters are made of reprocessed platinum group metals, and recycling these equipment is a smart solution to maintain sustainability, profitability and clean air on the planet. Is PGM recycling environmentally sustainable? The platinum group metals with the highest ability to neutralize harmful exhaust gases are platinum and palladium.

Although platinum is used in other fields, such as the production of magnets and jewelry, 90% of the palladium produced globally is currently used in catalytic converters. As Vermus explained, the extraction efficiency of palladium during mining is low, but the demand for a reliable source of this element is increasing: "Recent fuel standards, such as China VI, III, Euro 6d and Bharat 6 are all paying more attention. Clean air. This means that the demand for palladium is expected to rise in the near future, which makes car cat recycling essential to meet the needs of manufacturers around the world.

Of course, recycling platinum group metals is more environmentally friendly than mining them-the difference in carbon footprint alone is huge. As many countries promote sustainable development, platinum group metal recycling provides an excellent long-term solution for catalytic converter production, which can minimize the environmental damage associated with mining.

The XRF analyzer can perform fast elemental analysis, enabling users to accurately determine the concentration of Pt, Pd, and Rh in the spent catalyst within a few seconds. XRF devices such as the Vanta analyzer are also portable, which allows users to easily manage the various car kit materials that arrive for processing (Figure 3).

Vermus has extensive experience working with companies that use portable XRF devices for car and cat recycling, and knows their benefits. 'The fast and reliable analysis provided by the portable XRF analyzer enables users to quickly classify car cats into different groups based on parameters such as the best PGM extraction process and estimated purchase price. This helps users maintain a stable feed flow and speeds up the PGM extraction process.

In addition to identifying platinum group metals, the Vanta XRF analyzer series can also accurately measure 45 different elements from magnesium to uranium. However, the element group related to car cat recycling is much smaller, in addition to platinum group metals, it also includes: tantalum (Ta), cerium (Ce), selenium (Se), tungsten (W), silicon (Si), zirconium (Zr), Palladium (Pb), Lanthanum (La), Nickel (Ni) and Sulfur (S). To ensure direct analysis of all these elements, the Vanta analyzer also provides a dedicated car catalyst mode (CarCat).

“Since 2019, the composition of raw, crushed catalytic matrix materials on the market has undergone significant changes,” Vermus said. 'The average concentration of platinum group metals has doubled, and elements such as La, Ce, Hf and Zr have become more common. In order to give Vanta users full confidence in the accuracy of their measurements, we continue to develop CarCat Calibration, adding new standards and algorithms to enable them to quickly adapt to changes in market trends.

How should the catalytic converter be prepared for XRF analysis? Since 90% of the errors in XRF analysis are related to incorrect sample preparation, following the prescribed car cat preparation procedures is essential for optimal recovery efficiency. Car cat recycling usually involves two types of samples: block samples (whole or split) and powder samples. Since platinum group metals are unevenly distributed on the surface of the honeycomb structure of car cats, the bulk sample test can only provide a preliminary assessment, so that car cats can be distinguished by type and empty car cats that have been removed from platinum group metals can be rejected.

This stage is particularly important when purchasing small batches of raw materials. After this roughing stage (Figure 2), the material is divided into large batches for further enrichment through an additional sample preparation stage. These stages can be summarized as follows: 1) Rough classification of pacifiers by type and refusal; 2) Separate crushing of each group into powder of equal particle size; 3) Homogenization; and 4) Sampling-this may involve the use of a press .

Over time, using this program can build an extensive library of standard samples for comparison with incoming materials. According to Vermus, an important parameter to be considered in the subsequent XRF analysis is humidity.

'More than 10% humidity fluctuations will greatly affect the measurement accuracy. After obtaining the sample, an average of three to five tests should be performed during the XRF analysis. With proper sample preparation, the relevant error range should be between 4 ppm–31 ppm.

As Vermus explained, the portable Vanta analyzer has many benefits for users engaged in car cat recycling: "For users who regularly analyze a large number of incoming raw materials every day, it is important that the XRF equipment obtains a lot of results. Vanta analysis The instrument has a high calibration accuracy, which helps to ensure the best measurement accuracy, even in long-term use.

Olympus offers a variety of Vanta models for car and cat recycling. These models differ in analysis speed, sensitivity, and ability to determine light elements such as magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), and sulfur (S). For example, with an analysis time of 40–60 seconds and the ability to detect elements heavier than titanium, the Vanta L model equipped with a silicon PiN detector is most suitable for classifying raw materials by type.

In contrast, the analysis time of the Vanta C and M series is 15-20 seconds, and is equipped with silicon drift detector (SDD) technology, which can detect lighter elements. These models can be used to measure silicon carbide (SiC) content and can classify materials more accurately based on sulfur content. In addition, all models can be used with the portable desktop Vanta workstation, providing consistent sample positioning and efficient throughput (Figure 4).

With the growth of the scrap car catalyst market, car cat recycling companies are now facing another challenge-unscrupulous sellers try to increase the price of raw materials by using lead-containing additives to increase the quality of raw materials. Other more complex methods are also possible, such as adding tantalum or selenium to the mixture to simulate the XRF spectral peaks of platinum.

However, as an expert in XRF technology, Vermus has absolute confidence in the accuracy of the Vanta equipment: "Regardless of whether the inconsistency of raw materials is intentional or not, the unique calibration system and accuracy of the Vanta analyzer can help avoid such confusion and prevent the original An error occurred in the data process. Material analysis.

Or for companies with multiple engineers performing analysis, the Axon Technology electronic equipment of the Vanta analyzer can ensure consistent measurement results between different devices. This is an important advantage to prevent conflicts in the evaluation of elemental components. The Vanta device also provides a "User Factors" button, which provides a quick and easy way to adjust the device for different matrices.

According to Vermus, the future development direction of the car recycling industry is likely to involve more diversified analysis techniques: "As the industry develops, silicon carbide and sulfur content will play an increasing role in determining the cost of raw materials. "This will lead the company to choose equipment with SDD, or even brand new analytical equipment, such as X-ray powder diffractometer (XRD). For example, using Olympus's TERRA II portable XRD analyzer, users can not only obtain a quantitative estimate of the SiC content, but also determine its specific phase.

With the trend of increasing global environmental standards, the demand for platinum group metals will only grow. Choosing the right XRF or XRD analysis equipment can help companies prepare for the upcoming demand wave and give users confidence in their PGM measurement.

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