Quantitative characterisation of processed phlogopite ore from Silver City Dome District, Kansas, USA, by automated mineralogy

Historically, phlogopite and olivine have been mined in the Silver City Dome District in Kansas, USA, from lamproite ultra-potassic igneous rock for use as a supplement in cattle feed. Micro-Lite LLC is now evaluating processing techniques for recovery of phlogopite to be used for reinforcement in plastics, high temperature applications, and electrical insulators, which requires a higher grade phlogopite product. To determine the purity of the processed ore, QEMSCAN® was utilised to identify and quantify phlogopite and impurities, including olivine, pyroxenes, feldspars, titanium phases (mainly titanite and perovskite), apatite, magnetite, chromite, and other phases. Samples were prepared and analysed in a manner to decrease or eliminate preferred orientation of phlogopite to provide accurate quantitative results. The results show that the flotation product has a higher concentration of phlogopite at 87% (by mass), compared to 78% in the hydrosizer product. The main impurity phase in both products is olivine (10% in the flotation product and 18% in the hydrosizer product). In the hydrosizer product, 15% of the sample consists of liberated phlogopite particles, while in the flotation product 58% of the sample occurs as pure, liberated phlogopite particles.