Grant: Collaborative Research and Development Grants

Potash (KCl) production is a large and economically significant industry in Saskatchewan. Along with KCl, potash ore contains large quantities of Halite (NaCl). The chemical and physical similarity between these two minerals make them difficult to distinguish from each other in the ore. This leads to problems maintaining a consistent feedstock to the mill. A similar problem arises in determining the relative concentrations of KCl and NaCl in solution. The current state of the art is to use the radioactive decay of the naturally occurring K40 isotope, or off-line X-ray techniques. The equipment required for these approaches is expensive and not conducive for on-line monitoring and process control.UV-Visible-NIR spectroscopy and imaging have not been thoroughly investigated for distinguishing between these two minerals. In the solid phase, the visible and near-infrared spectra of pure KCl and NaCl are virtually indistinguishable. However, anecdotal evidence from miners suggests visual differences between minerals in the ore formation. In solution, it has been established that total Cl ion concentration may be determined using spectroscopy by analysis of side-effects on water absorption bands. Limited work has been done on speciation of the salts in solution. This work proposes to systematically study whether spectroscopic and imaging techniques can be applied in two scenarios in the potash industry. Techniques will be developed to measure absorption spectra of high-temperature solutions, and the spectral characteristics of single and multiple-species solutions investigated. Exploratory work will be conducted on using machine vision and imaging spectroscopy techniques for ore grading. These investigations will create new knowledge in the area of spectroscopy, and support the development of industrially viable on-line assessment tools.