Measurement of Metal Grade of Ore Particles in Slurry Using Laser-Induced Breakdown Spectroscopy

This paper describes experimental works to apply Laser-Induced Breakdown Spectroscopy (LIBS) for in-situ measurement of the metal grade of ore particles handled in seafloor mineral processing system for seafloor massive sulfides. LIBS measurements of ore particles containing metallic elements in slurry were performed, where ore slurry was circulated through a chamber mounted on the optical probe of a LIBS device. The chamber was positioned to set the focal point of laser from the LIBS device at the center of the tubular space in the chamber, where the slurry runs. Analytically useful LIBS spectra were obtained from the slurry with enough slurry concentration. While relatively strong LIBS signals assigned to major elements appeared in many spectra, sharp LIBS signals assigned to minor elements appeared in a spectrum. Individual ore particles are not homogeneous even though they are prepared from single ore. The results suggest that multiple measurements are required to assess the metal grade in the seafloor mineral processing system.