In-situ monitoring and characterization of airborne solid particles in hostile industrial environments using stand-off LIBS

Abstract

The analytical possibilities of laser induced breakdown spectroscopy (LIBS) to carry out in-situ and real-time detection and compositional characterization of solid aerosols in the atmosphere of a steelmaking factory, have been evaluated. To this aim, a compact and versatile dual-pulse LIBS analyzer, able to sample at distances up to eight meters, has been design to work under these hostile industrial environments. Due to the discrete nature of the particulate matter, the particle sampling rate was less than 2.5% and 6% for single- and double-pulse regimes, respectively. An efficient statistical procedure, based on the calculation of standard deviations, is used to qualitatively characterize the elemental composition of the aerosol. Then, a conditional analysis based on the limit of detection, is employed to assess the elemental sampling rate. This experimental methodology has been used to evaluate the influence on the aerosol formed of the oxycutting process in a continuous casting machine producing steel slabs, revealing a strong presence of elements derived from the casting powder used in the production. Moreover, chromium, present in the steel cast, is detected in suspension in the steel shop. An increase in the concentration of particulate matter when oxycutting is working is suggested. Single-pulse and dual-pulse excitation modes are also evaluated.