Application of Laser-Induced Breakdown Spectroscopy for in-situ measurement of metal grade for seafloor mineral processing

This paper describes experiments carried out to investigate the application of Laser-Induced Breakdown Spectroscopy (LIBS) to measure the metal grade of seafloor massive sulfides in situ as part of a deep-sea mineral processing system. In the experiment, particles of sulfide minerals containing metallic elements such as copper, lead and zinc were used. The measurements were performed in bulk liquids containing ore particles dispersed in slurry and on particles that were fixed on an aluminum plate submerged in water. Well-resolved spectra were obtained from both the dispersed and the fixed particles. However, the ratio of well-resolved spectra was significantly higher for the fixed particles than those dispersed in slurry. The results are promising for in-situ assessment of metal grade during seafloor mineral processing, but suggest that it is necessary to manipulate the particles so that they are concentrated near the focal point of the laser and do not obstruct the laser path.