Scalable recycling of feldspar slime into high-quality concentrates by removal of colored minerals using the combined beneficiation processes

Abstract

Feldspars are the main raw materials for glass and ceramics. The feldspar slime generated during beneficiation processes contains a high content of colored iron-bearing minerals, which is an obstacle to its utilization. In this study, dishwashing liquid is used as the flotation collector and frother, and combined beneficiation processes, including wet ball milling, froth flotation and magnetic and gravity separation, are employed to remove the iron-bearing minerals from feldspar slime in order to achieve high-quality concentrates. In the milling process, slime particles are pulverized to liberate fine impurity minerals, which are gradually separated and removed by the subsequent processes with the assistance of anionic surfactants in the collector. The mass recovery of feldspar concentrates decreases with increasing milling time and first decreases and then increases with increasing collector dosage. While the burnt whiteness of feldspar concentrates first increases and then decreases with increasing milling time and collector dosage, it continuously decreases with the prolongation of gravity sedimentation. When feldspar slime is milled for 2 h, floated with a 2% collector dosage and settled for 10 h in gravity separation, the resulting feldspar concentrate contains 12.6% Na2O + K2O and 0.21% Fe2O3, with a mass recovery and burnt whiteness of 58.0% and 53.6%, respectively. This feldspar concentrate meets the requirements of the glass and ceramics industries. The scalable and environmentally-friendly recovery of feldspar slime represents a promising route for the sustainable utilization of feldspar minerals.