The Industrial Application of Molten Metal Analysis (LIBS)

The chemical composition and cleanliness of molten metal is of fundamental importance in metal production. Traditional methods to test the chemical composition of a molten bath requires periodic sampling and the use of a lab based spark optical emission spectrometer (OES). Laser-induced breakdown spectroscopy (LIBS), has been shown to be a useful tool for quick, reliable analysis of molten metal in a production setting in situ and in near real time. LIBS uses a high energy laser to fire into the melt and creates a microscopic plasma that in turn emits light that is characteristic of each element type and its concentration present. A spectrometer is used to identity each element and its concentration within the melt. A LIBS system, marketed as OnSpec® has been developed for the aluminum industry to provide real-time bulk metal chemistry of molten metal in both furnace and launder applications. The same OnSpec® hardware can also be configured to measure melt cleanliness, providing information about the loading, size distribution, and chemistry of inclusions. The ability to measure and characterize inclusions is currently in the research phase. A patent has been issued, another is in process, and another is being written. This paper reports on successful field tests conducted of the OnSpec® system at various aluminum facilities and discusses its potential applications and benefits.