Quantification of fluorite mass-content in powdered ores using a Laser-Induced Breakdown Spectroscopy method based on the detection of minor elements and CaF molecular bands

摘要

Laser Induced Breakdown Spectroscopy (UBS) is investigated as a fast and robust method to determine the fluorite (CaF2) mass-content of powdered ore samples. Calibrating samples covering a wide CaF2 concentration range (from 23 to 97.6%) are employed. LIBS operating conditions are optimized for the analysis of elemental emission lines and molecular bands, respectively. In particular, LIBS emission intensities from different CaF molecular bands are evaluated to calibrate the fluorite concentration as an alternative to the use of atomic fluorine F I emission lines. Furthermore, the determination of LIBS emission signals from minor elements (e.g. Si I and Mg I) is studied to further improve the accuracy and precision of pure fluorite sample analyses (e.g. [CaF2] > 75%). The proposed LIBS method avoids the tedious dissolution processes that are required by other analytical methods employed in mining industry for the quantitative analysis of fluorite.