Green and sustainable recovery of feldspar and quartz from granite tailings

Abstract

Granite tailings are rich in quartz and feldspar with high recycling value. However, quartz-feldspar separation usually adds sulfuric acid and hydrofluoric acid, which inevitably leads to equipment corrosion and environmental pollution. This study introduced an alkaline-based flotation method to treat granite tailings. In this approach, mica was first floated by adding Na2CO3 as pH adjuster and sodium oleate/octanol with mass ratio 9/1 (NaOT) and dodecylamine acetate as mixed collector. Then, the quartz-feldspar separation was achieved using NaOH as pH adjuster, MgCl2 as activator, and NaOT as collector. The results of the flotation test showed that the yield of quartz products was 24.51% with a grade of 96.04% SiO2, and the yield of feldspar products was 41.77% with a grade of 14.06% K2O and Na2O. The economic analysis demonstrated that the flotation process in this study yields a profit of 50.96 USD per ton of treated tailings. Overall, this approach possesses the advantages of excellent selectivity, obvious economic efficiency, and environmental friendliness, making it highly suitable for industrial applications with immense potential.