On mining operations, Grade-control is based on laboratory measurements from blast-hole samples or appropriate type of well logging (e.g. gamma logging) to characterize each block. The problems with these techniques are that they slow, costly and the results are not immediately available. To overcome these issues, it is essential to develop new sensor technologies that can provide elemental and mineralogical information real-time and on-site.
Here, a case study using Laser-Induced Breakdown Spectroscopy (LIBS) and samples of Parainen limestone quarry is presented. The aim of the research was to resolve, if LIBS measurements can be used to characterize the ore body during the blast-hole drilling. The quality parameters that are used in Parainen for the ore grade evaluation are Ca/Si+Al and the magnesium content of the samples. The samples consisted of drill cuttings samples from three different blast-holes and four bulk samples of different ore grades collected from the stockpiles. The bulk samples were crushed, sieved and resorted to get the same grain size distribution with the drill cuttings. The cuttings and the crushed bulk samples were measured by free falling them via funnel to mimic the moving particles in the drill tube.
The results from the LIBS measurements were validated using synchrotron X-ray diffraction and gamma logging from the blast-holes. Our preliminary results suggest that LIBS can be used as an on-line analyzing technique during the drilling process. The ore type and an approximation of the ore grade can be detected from the spectral data.