Separation and Recovery of Iron and Rare Earth from Bayan Obo Tailings by Magnetizing Roasting and (NH4)2SO4 Activation Roasting

A novel approach for recovery of iron and rare earth elements (REEs) from Bayan Obo tailings of Baotou, China, was developed by combining magnetizing roasting, magnetic separation, (NH4)2SO4 activation roasting, and water leaching. Thermodynamic analysis of carbothermal reduction was conducted to determine the temperature of magnetizing roasting, and it agreed well with the experimental results. The maximum recovery of Fe reached 77.8% at 600 °C, and the grade of total Fe in the magnetic concentrate was 56.3 wt. %. An innovative approach, using water to leach REEs after (NH4)2SO4 activation roasting, was used to extract REEs from magnetic separation tailings. The main influence factors of the leaching recovery during (NH4)2SO4 activation roasting, were investigated with the mass ratio of (NH4)2SO4 to magnetic separation tailings, roasting temperature and roasting time. The leaching recoveries of La, Ce and Nd reached 83.12%, 76.64% and 77.35%, respectively, under the optimized conditions: a mass ratio of 6:1, a roasting temperature of 400 °C and a roasting time of 80 min. Furthermore, the phase composition and reaction process during the (NH4)2SO4 activation roasting were analyzed with X-ray diffraction (XRD), energy dispersive X-ray spectroscopy & scanning electron microscopy (EDS-SEM) and thermogravimetry & differential scanning calorimetry (TG-DSC), and the leaching solution and leaching residue were also characterized.

[1]  Yifang Zhu,et al.  Atmospheric thorium pollution and inhalation exposure in the largest rare earth mining and smelting area in China. , 2016, The Science of the total environment.

[2]  He Yang,et al.  Magnetizing roast and magnetic separation of iron in rare-earth tailings , 2016 .

[3]  M. A. Bykov,et al.  Phase transitions of some sulfur-containing ammonium salts , 2014 .

[4]  Lingqing Wang,et al.  Accumulation and fractionation of rare earth elements in atmospheric particulates around a mine tailing in Baotou, China , 2014 .

[5]  Q. Xue,et al.  Recovery Behavior of Rare Earth from Bayan Obo Complex Iron Ore , 2013, Metallurgical and Materials Transactions B.

[6]  Zhichao Yang,et al.  Recovery of valuable metals from a low-grade nickel ore using an ammonium sulfate roasting-leaching process , 2012, International Journal of Minerals, Metallurgy, and Materials.

[7]  Qing Wang,et al.  Recovery of Rare Earths, Niobium, and Thorium from the Tailings of Giant Bayan Obo Ore in China , 2012, Metallurgical and Materials Transactions B.

[8]  Yongfu Yu,et al.  Magnetizing roasting mechanism and effective ore dressing process for oolitic hematite ore , 2011 .

[9]  D. J. Lecaptain,et al.  In Situ Raman Spectroscopic Analysis of the Regeneration of Ammonium Hydrogen Sulfate from Ammonium Sulfate , 2007 .

[10]  N. Krishnamurthy,et al.  Extractive metallurgy of rare earths , 1992 .

[11]  H. I. Saleh,et al.  Extraction of zinc from blast‐furnace dust using ammonium sulfate , 2004 .

[12]  Gunnar Eriksson,et al.  FactSage thermochemical software and databases , 2002 .

[13]  L. Ke.  Studies on the thermal decomposition of ammonium sulfate , 2002 .

[14]  V. Venugopal,et al.  Solid state reactions of CeO2, ThO2 and PuO2 with ammonium sulphate , 1999 .

[15]  K. Urano,et al.  Mechanism, Kinetics, and Equilibrium of Thermal Decomposition of Ammonium Sulfate , 1970 .