Sulfur Detection in Coke by Laser-Induced Breakdown Spectroscopy

Accurate determination of sulfur (S) content in coke is of great significance to improve the quality of iron and steel. In this study, the sulfur in coke standard samples was detected in argon (Ar) atmosphere using laser-induced breakdown spectroscopy (LIBS), and S I 182.034 nm was chosen as the analytical line. The experimental results showed that it was advantageous to detect S in the early stage of plasma generation. Compared with tablet samples, the spectral intensities of binder samples on the copper foil tape were greater and the signal-to-noise ratio (SNR) was also greater. As for reduplicate experiments, the coefficient of variation (CV) of spectral intensities of binder samples was 10.58% and that of tablet samples was 88.54%. The plasma signal induced by binder samples was stronger and more stable. The internal standard method and support vector machine regression (SVR) were used to quantitatively analyze the sulfur content in binder samples, and SVR showed more accurate prediction accuracy. R2 of SVR with electron density and self-absorption correction was 0.965, root mean square error of prediction (RMSEP) was 0.18 wt.% and the limit of detection (LOD) was 0.026%. This result proved the applicability of binder for sulfur measurement in coke using LIBS.