An alternative source for ceramics and glass raw materials: Augen-gneiss

Due to the depletion of well-known feldspar reserves in the forms of granite, trachyte and pegmatite, many investigations are focused on new and economic alternatives to these resources. Of these, gneiss is a metamorphic rock type, which is characterized by dark and light colored minerals including feldspar and quartz. In this study, Augen-Gneiss rock was subjected to flotation tests to produce alkali (Na + Ca) feldspar and quartz concentrates by adapting different flotation conditions with/without hydrofluoric acid (HF). During these tests, the effect of particle size and different reagent combinations were investigated. The results of these tests showed that, in the presence of HF, a saleable feldspar concentrate with 0.04% Fe₂O₃ content and a saleable quartz concentrate with 98.45% SiO₂ content were obtained. Products with similar qualities to a feldspar concentrate with 0.13% Fe₂O₃ and a quartz concentrate with 92.53% SiO₂ content were produced without HF. The results of these tests clearly showed that, compared to other types of origin, saleable quality feldspar and quartz could well be enriched with/without HF from Augen-Gneiss rock.