Flocculation Behavior And Dispersion Mechanism During Flotation Separation Of Quartz And Feldspar In Alkaline Environment

Flotation is an effective method for separating quartz and feldspar resources from granite tailings.Quartz can be floated preferentially by using metal ions and anionic collectors in alkaline pulp,which is more eco-friendly than acid and HF.However,in the practical application process,the separation efficiency of quartz and feldspar is restricted due to the indiscriminate agglomeration and coagulation of quartz and feldspar particles caused by factors such as excess ion components and shear flocculation.This paper systematically studied the flotation behavior of quartz and feldspar in alkaline environment,compared and analyzed the flotation difference of single/mixed mineral,explored the effect of different dispersants,discussed the control mechanism of inter-particle dispersion and flocculation behavior through potentiometric potential,Raman spectroscopy and X-ray photoelectron spectroscopy analysis,and realized efficient separation of quartz and feldspar in kaolin tailings.The main research conclusions are as follows:The flotation behaviors of single and artificial mixed mineral show inter-particle coagulation leads to the entrainment of feldspar increased in quartz concentrate,and the recovery of feldspar in concentrate increases29.5%while the separation index is 4.7.The effect of five dispersants such as sodium carbonate on the dispersion effect and recovery index of flotation process is explored.The dispersion effect are as follows:FSD>sodium pyrophosphate>sodium carbonate>citric acid>EDTA.When the dosage of FSD is 120 mg/L,the maximum separation index is 10.3,showing great dispersion.The effect of metal ions on dispersion during flotation of quartz and feldspar particles shows that multiple components in the alkaline solution have different effects on the particles:Ca（OH）⁺,Ca（OH）_2（aq）,Mg（OH）⁺,Mg（OH）_2（aq）are effective activation components;Ca²⁺and Mg²⁺compress the electric double layer and weaken the electrostatic potential energy between particles;Ca（OH）_2（aq）and Mg（OH）_2（aq）cover the particles surface by surface precipitation,so the surface charge is shielded and the electrostatic repulsion between particles lost.The dispersion mechanism of FSD is:The polyhydroxy groups at the FSD adsorbed on the Al³⁺of feldspar,which strengthens the electrostatic potential energy between particles,and produces steric hindrance effect and strong hydration repulsion force at the same time,so it enhances the dispersion between particles.The theoretical analysis of EDLVO shows that the dominant force between particles before the addition of FSD is hydrophobic gravitational force,and the interparticle force of feldspar after FSD adsorption on the surface of feldspar is dominated by hydration repulsion and space sterically repulsion.Through one stage rougher flotation,two stage scavenging and three stage cleaning,quartz concentrate products with a yield of 30.61%and a content of 98.41%SiO₂,meanwhile feldspar products with a yield of 25.43%and a content of 11.29%K₂O and 1.31%Na₂O,are obtained from kaolin tailings.