Remote analysis of a mineral melt by laser-induced plasma spectroscopy

The performance of a customized mobile laser-induced plasma spectroscopy (LIPS) system, based on a Nd:YAG laser for plasma ignition and an echelle spectrometer with an intensified charge-coupled device (CCD) camera, was tested during a field campaign for in situ and on-line process analysis of major constituents in a mineral melt of 1600 degreesC. After an optimization of the instrumental parameters, such as irradiance, gate width, and delay of the integration time relative to the laser pulse, LIPS allowed the on-line identification of all elements relevant for mineral wool production (i.e., Ti, Fe, Mn, Mg, Ca, Si, Na, and Al) directly from the melt in a rather harsh industrial environment. Validation of the LIPS analysis was performed via manual sampling and X-ray fluorescence (XRF) analysis. A reasonable correlation between the LIPS analysis and the reference analysis was obtained considering the experimental constraints; LIPS demonstrated, however, a superior temporal resolution. The observed differences between LIPS and XRF analysis during load changes of the oven are probably due to unknown processes in or on the melt or rheological effects, which were not detected by bulk reference analysis.