Surface magnetization of siderite mineral

Surface self-magnetization of siderite is achieved by generating ferromagnetic substance on the surface of siderite by adjusting slurry temperature, pH value, stirring rate and reaction time. No addition of any iron-containing reagent is required. The temperature of 60 degrees C, NaOH concentration of 0.10 mol/L; stirring rate of 900 r/min and the reaction time of 10 min are the optimal conditions. The results show that the siderite recovery in magnetic separation increased from 26.9% to 88.8% after surface magnetization. Magnetization kinetic equation is expressed as 1 - [1 - (epsilon - 0.269)](1/3) = Kt. Activation energy for the magnetization reaction is 4.30 kJ/mol. VSM, SEM and XPS were used to characterize the siderite, and results show that the saturated magnetization (rs) of siderite increased from 0.652 to 2.569 A m(2)/kg, the magnetic hysteresis was detected with a coercive force of 0.976 A/m after magnetization; Fe2P3/2 electron binding energy changed which reflects the valence alteration in iron on the surface and the formation of ferromagnetic Fe3O4. (C) 2012 Published by Elsevier B.V. on behalf of China University of Mining & Technology.