Furnace Fast Carbon-Silicon Analyzer

The pre-furnace fast carbon-silicon analyzer is a critical tool used to detect and analyze the content of carbon and silicon in steel. These two elements play a vital role in determining the quality, strength, and overall performance of the final product. Therefore, conducting accurate pre-furnace analysis is essential for ensuring consistent and high-quality steel production.

When performing elemental analysis using a spectrometer, interference calibration becomes necessary when an element's spectral line is used for measurement and there are nearby lines that could cause a "line effect." If the spectrometer’s resolution isn’t sufficient to eliminate this interference, the measured value can be significantly higher than the actual content due to overlapping light intensities. This is why it's crucial to understand and prevent such interferences during the analytical process.

Manufacturers of spectrometers often try to avoid these disturbing elements by carefully selecting the spectral lines used for analysis. However, in some cases, interference cannot be completely avoided, especially when dealing with complex materials or multiple elements present in the sample.

There are two primary methods for preventing elemental interference:

1. Select undisturbed spectral lines: When measuring low levels of elements like aluminum, it's common to choose two sensitive lines. For example, the Al 394.4nm line and the Al 396.1nm line. While the 396.1nm line is more sensitive, it may be affected by the presence of molybdenum (Mo). In such cases, the 394.4nm line is often preferred for analyzing low concentrations of aluminum in steel. Spectrometer manufacturers typically select appropriate lines based on the material being tested and the substrate conditions.
2. Use a spectrometer with higher resolution: Higher resolution spectrometers, such as those with longer focal lengths, can better separate overlapping spectral lines. For instance, a 3m spectrometer has greater resolution compared to a 1m model. However, increasing the focal length also leads to larger physical dimensions, less optical stability, and reduced light intensity reaching the photomultiplier tube. To address these challenges, secondary diffraction orders are often used. The resolution of the secondary spectrum is approximately twice that of the primary one. For example, with an entrance slit width of 25μm and an exit slit width of 88μm, the primary spectrum resolution is 0.0375nm, while the secondary is 0.0188nm. If the entrance slit is narrowed to 10μm, the secondary spectrum resolution can reach as low as 0.0058nm.

As the number of spectral orders increases, the energy level gradually decreases. In non-luminous regions, the intensity of the secondary spectrum is only about 25% of the primary one. Using a concave grating with 1440 lines/mm is a key factor in determining the wavelength range and resolution of the spectrometer. The first-order spectral range typically spans from 346.0nm to 767.0nm, covering sensitive lines of elements like sodium (Na), lithium (Li), and potassium (K). There is no additional optical path involved in this design, and longer wavelengths generally result in less interference. The second-order spectral range usually falls between 173.0nm and 383.5nm, covering elements like phosphorus (P), sulfur (S), and boron (B). This region offers better emission spectra and improved resolution.

The pre-furnace rapid carbon-silicon analyzer discussed above highlights the importance of understanding and mitigating elemental interference in spectral analysis. Properly addressing these issues significantly enhances the accuracy and reliability of the analytical results, which is crucial for maintaining the quality of steel production and other metallurgical processes.