Liaoning Key Laboratory of Recycling Science for Metallurgical Resources

Shenyang, China

Liaoning Key Laboratory of Recycling Science for Metallurgical Resources

Shenyang, China
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Cheng G.,Northeastern University China | Gao Z.,Northeastern University China | Lv M.,Northeastern University China | Yang H.,Northeastern University China | And 3 more authors.
Minerals | Year: 2017

Coal-based reduction and magnetic separation behavior of low-grade vanadium-titanium magnetite pellets were studied in this paper. It is found that the metallization degree increased obviously with an increase in the temperature from 1100° C to 1400° C. The phase composition transformation was specifically analyzed with X-ray diffraction (XRD). The microscopic examination was carried out with scanning electron microscopy (SEM), and the element composition and distribution were detected with energy dispersive spectroscopy (EDS). It is observed that the amounts of metallic iron particles obviously increased and the accumulation and growing tendency were gradually facilitated with the increase in the temperature from 1100° C to 1400° C. It is also found that the titanium oxides were gradually reduced and separated from ferrum-titanium oxides during reduction. In addition, with increasing the temperature from 1200° C to 1350° C, silicate phases, especially calcium silicate phases that were transformed from calcium ferrite at 1100° C, were observed and gradually aggregated. However, at 1400° C some silicate phases infiltrated into metallic iron, as it appears that the carbides, especially TiC, could probably contribute to the sintering phenomenon becoming serious. The transformation behavior of valuable elements was as follows: Fe2 VO4 → VO → V → VC; FeTiO3 (→ FeTi2 O5) → TiO2 → TiC; FeCr2 O4 → Cr → CrC; FeTiO3 (→ FeTi2 O5) → Fe0.5 Mg0.5 Ti2 O5; (Fe3 O4 /FeTiO3 →) FeO → Mg0.77 Fe0.23 O. Through the magnetic separation of coal-based reduced products, it is demonstrated that the separation of Cr, V, Ti, and non-magnetic phases can be preliminarily realized. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.


Cheng G.,Northeastern University China | Gao Z.,Northeastern University China | Yang H.,Northeastern University China | Yang H.,Liaoning Key Laboratory of Recycling Science for Metallurgical Resources | And 2 more authors.
Metals | Year: 2017

The effect of calcium oxide on the crushing strength, reduction, and smelting performance of high-chromium vanadium–titanium magnetite pellets (HCVTMP) was studied in this work. The main characterization methods of an electronic universal testing machine (EUTM), X-ray fluorescent (XRF), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), and scanning electron microscope-energy disperse spectroscopy (SEM-EDS) were employed. The crushing strength was affected by the mineral phases generated during oxidative baking and the subsequently-formed pellet microstructures owing to CaO addition. The reduction and smelting properties of HCVTMP with different CaO additives were measured and characterized with different softening-melting-dripping indices. Although HCVTMP showed the highest crushing strength with CaO addition of ca. 2 wt %, more CaO addition may be needed to achieve high permeability of the furnace burdens and a good separation condition of the slag and melted iron. In the formation process of the slag and melted iron, it can be determined that CaO could have a relationship with the transformation behavior of Cr, V, and Ti to some extent, with respect to the predominant chemical composition analysis of ICP-AES and XRF. With the microscopic examination, the restraining formation of Ti(C,N) and the promoting formation of CaTiO3 are in accordance with the improved melting-dripping indices, including the decrease of the maximum external static load and gas permeability, and the increase of the melting-dripping zone and dripping difficulty. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.


Zhou Y.,Northeastern University China | Zhou Y.,Liaoning Key Laboratory of Recycling Science for Metallurgical Resources | Yang H.,Northeastern University China | Yang H.,Liaoning Key Laboratory of Recycling Science for Metallurgical Resources | And 4 more authors.
Metals | Year: 2017

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. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.

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