Characteristics of laser-induced breakdown spectroscopy of liquid slag

Abstract Rapid online analysis of liquid slag is essential for optimizing the quality and energy 
efficiency of steel production. To investigate the key factors that affect the online measurement of 
refined slag using laser-induced breakdown spectroscopy (LIBS), this study examined the effects 
of slag composition and temperature on the intensity and stability of the LIBS spectra. The 
experimental temperature was controlled at three levels: 1350, 1400, and 1450 °C. The results 
showed that slag composition and temperature significantly affected the intensity and stability of 
the LIBS spectra. Increasing the Fe content and temperature in the slag reduces its viscosity, 
resulting in an enhanced intensity and stability of the LIBS spectra. Additionally, 42 refined slag 
samples were quantitatively analyzed for Fe, Si, Ca, Mg, Al, and Mn at 1350, 1400, and 1450 °C. 
The normalized full spectrum combined with partial least squares (PLS) quantification modeling 
was used, using the Ca II 317.91 nm spectral line as an internal standard. The results show that using the internal standard normalization method can significantly reduce the influence of spectral 
fluctuations. Meanwhile, a temperature of 1450 °C has been found to yield superior results 
compared to both 1350 and 1400 °C, and it is advantageous to conduct a quantitative analysis of 
the slag when it is in a water-like state with low viscosity.