Quantitative analysis of P2O5 in solid raw phosphate matrices using laser-induced breakdown spectroscopy (LIBS) for online mining industry monitoring

Laser-Induced Breakdown Spectroscopy (LIBS) is increasingly considered for real-time compositional monitoring in the mining industry, offering minimal sample preparation, multi-element capability, and sub-second analysis times. The growing global demand for fertilizers, combined with the progressive depletion of high-grade phosphate ore, highlights the need for fast, accurate, and reliable analytical methods for upstream process control. This work develops and validates a complete LIBS calibration protocol for the quantitative determination of \(P₂O₅\) in solid phosphate rocks. A set of 84 calibration samples, prepared by gravimetric dilution of NIST SRM 694, spanning 6.4–24.8 wt.% \(P₂O₅\) and characterized by ICP-OES was used to build quantitative models by systematically benchmarking 30 calibration configurations crossing six regression families, three variable-selection strategies, and two replicate-handling schemes, on spectra preprocessed by Savitzky–Golay smoothing combined with standard normal variate (SNV) normalization. The optimal configuration, based on partial least squares regression achieved a coefficient of determination \(R²CV = 0.949\) and a root-mean-square error \(RMSECV = 1.16\:wt.{%}\:\) \(P₂O₅\) . These results establish a laboratory validated calibration baseline and suggest that LIBS, coupled with chemometric modeling, constitutes a credible candidate for real-time, upstream \(P₂O₅\) monitoring in phosphate-mining operations, pending validation on site under actual production conditions.