Shooting slurries with laser-induced breakdown spectroscopy: sampling is the name of the game

Analyses of iron ore slurries in industrial and laboratory environments showed that many physical and geometric parameters affect the stability and reproducibility of the response to laser-induced breakdown spectroscopy. A thorough reexamination of the sampling strategy led to a revised sampling layout that ensures a true representative sampling of the slurry and significantly improves the sensitivity and repeatability of the sampling method. An examination of the characteristics of slurries revealed that the mean particulate size and the concentration of solids in a slurry influence the measurement of silica, whereas the magnetite content is responsible for a matrix effect. On-line monitoring of iron ore slurries should be practicable, provided that these variables are controlled within a few percent or that some means of correction is implemented.