Accurate Real-Time Elemental (LIBS) Analysis of Molten Aluminum and Aluminum Alloys

Abstract

Real-time LIBS (laser induced breakdown spectroscopy) analysis for monitoring and process control in an aluminum smelter is reported. Chemical analysis was carried out directly in a casting launder as well as with robotic sample feeding at a crucible skimming station. Using this system, ppm-level quantification limits have been demonstrated for certain trace elements. For most of the elements studied, measurement uncertainty is lower than observed in OES (optical emission spectroscopy) analysis on corresponding process samples. Furthermore, LIBS analysis allows the time-varying concentration of elements in the melt to be monitored on a minute-by-minute basis. Our results confirm that for many technologically important elements, LIBS analysis represents a competitive alternative to laboratory OES, provided that suitable access to the liquid aluminum can be ensured. This approach improves plant safety by reducing the need for manual sampling of liquid metal, eliminates operator-related errors in chemical analysis and is critical for automation of casthouse operations.