Synthesis and characterization of magnetic nanoparticles from raffinate of industrial copper solvent extraction plants

Magnetite nanoparticles successfully produced from the raffinate of an Iranian industrial copper solvent extraction unit. Removal of iron from leach solution is important for successful operation of hydrometallurgical recovery of copper. It includes reduction of Fe3+ to Fe2+ followed by precipitation of Al3+ as Al(OH)(3), oxidation of Fe2+ to Fe3+ (the theoretical ratio for stoichiometric, Fe3+/Fe2+ = 2) and finally synthesize of nano-sized magnetite. Two different Fe2+ oxidation agents namely H2O2 and O-2 were used. Using XRD, FTIR, FESEM, and TEM analysis, the phase structure, morphology, and size distribution of magnetic nanoparticles, produced under different conditions, were evaluated and compared. Under optimum conditions spherical magnetic nanoparticles with an average size of about 25 +/- 3 nm can be produced. The XRD analysis of produced nanoparticles after purification of raffinate showed the slight formation of aluminum hydroxide, goethite and hematite phases. In addition, the VSM results indicate the highly ferromagnetic behavior for samples at the room temperature with a saturation magnetization of 41.25 emu/g.