Selective depression depression of silicates in phosphate flotation using polyacrylamide-grafted nanoparticles

In this study, novel in-house synthesized hybrid polyacrylamide-grafted nanoparticles (Hy-PAM) were used to enhance the recovery of phosphorus bearing minerals from plant tailing by the froth flotation process. Characterization assays, including X-ray diffraction (XRD) and mineral liberation analysis (MLA) indicated that apatite, fluorapatite and quartz are the major crystalline phases in the tailing sample. Flotation experiments were performed using a bench scale Denver flotation cell with 1 L capacity in the presence of sodium oleate, which was used as a collector. Several influencing parameters such as polymer dosage, pH, and the flotation time were investigated to optimize the flotation outcomes in terms of recovery and grade of phosphorus pentoxide (P2O5). Results indicated that the P2O5 content in the plant tailings can be enriched from 21.6% to 28.6% at a recovery value of 80.5% in the first 4 min of flotation without the need to add a pH modifier. Moreover, flotation kinetics was investigated using classical first order kinetic model which was evaluated based on the flotation rate constant, the ultimate phosphorous recovery and the correlation coefficients obtained by non-linear regression analysis. Results indicated that the ultimate recoveries and the flotation rate constant values were affected by the change of the pulp's pH.