Bingbing Liu

Selective separation and recovery of iron and tin from high calcium type tin- and iron-bearing tailings using magnetizing roasting followed by magnetic separation

ABSTRACT In this study, a process of magnetizing roasting followed by magnetic separation, which is used to separate or recover tin and iron from the high calcium type tin- and iron-bearing tailings (containing 35.53 wt.% Fe and 0.56 wt.% Sn), was investigated . A magnetic concentrate containing 66.3 wt.% Fe and 0.07 wt.% Sn with an iron recovery rate of 92.9 wt.% was obtained under optimal conditions: anthracite ratio of 2.5:100, roasting temperature of 850°C, roasting time of 30 min, grinding time of 10 min, and magnetic field intensity of 0.1 T. In addition, the effect of roasting parameters on the separation of iron and tin and phase transformation of SnO2 was investigated by using X-ray powder diffraction, Scanning Electron Microscopy–Energy Dispersive Spectroscopy, etc.

Consolidation Behavior of High-Fe Manganese Ore Sinters with Natural Basicity

ABSTRACT High-iron content manganese ore resources are becoming the mainstream raw ores for manganese extraction due to the depletion of high-grade manganese ores. Our previous research has reported the optimization parameters for the sintering of high-Fe manganese ore (abbr. high-Fe Mn-ore) fines. This study further investigated the consolidation behavior of high-Fe Mn-ore sinters with natural basicity. Sintering pot tests showed that the high-Fe Mn-ore sintering required high coke breeze dosage (about 9.9 wt.%). The CO content of the outlet flue gas (7.5 vol.%~8.0 vol.%) in the high-Fe Mn-ore sintering was higher than that in the ordinary iron ore sintering (1.0 vol.%~2.2 vol.%). XRD and SEM-EDS analyses indicated that the major mineral phases in the sinters included Fe-Mn oxides (FexMn3-xO4), ferrotephroite ((Fe,Mn)2SiO4), Ca-,Al-,Mn-,Fe- bearing silicate melts, and a small quantity of hausmannite (Mn3O4) and free quartz (SiO2). Optical microstructure and SEM images showed that the Fe-Mn oxides, Ca-, Al-, Mn-, Fe- bearing silicate melts and ferrotephroite particles are closely interconnected with one another. The formation of Fe-Mn oxides and ferrotephroite were beneficial to the sinter strength. Thermodynamic and phase diagram analyses further demonstrated that the major bonding phases of Fe-Mn oxides and ferrotephroite were easily formed under the strong reductive sintering atmosphere of high-Fe Mn-ores.

Formation mechanisms of Fe 3−x Sn x O 4 by a chemical vapor transport (CVT) process

Our former study reported that Fe-Sn spinel (Fe3−xSnxO4) was easily formed when SnO2 and Fe3O4 were roasted under CO-CO2 atmosphere at 900–1100 °C. However, the formation procedure is still unclear and there is a lack of theoretical research on the formation mechanism of the Fe-Sn spinel. In this work, the reaction mechanisms between SnO2 and Fe3O4 under CO-CO2 atmosphere were determined using XRD, VSM, SEM-EDS, XPS, etc. The results indicated that the formation of Fe3−xSnxO4 could be divided into four steps: reduction of SnO2 to solid phase SnO, volatilization of gaseous SnO, adsorption of gaseous SnO on the surface of Fe3O4, and redox reaction between SnO and Fe3O4. During the roasting process, part of Fe3+ in Fe3O4 was reduced to Fe2+ by gaseous SnO, and meanwhile Sn2+ was oxidized to Sn4+ and entered into Fe3−xSnxO4. The reaction between SnO2 and Fe3O4 could be summarized as Fe3O4 + xSnO(g) → Fe3−xSnxO4 (x = 0–1.0).

Effect of CaCO3 on the Gaseous Reduction of Tin Oxide Under CO-CO2 Atmosphere

ABSTRACT Calcite (CaCO3), one of the main impurities, has an uncertain effect on the volatilization behavior of tin oxide in the tin-bearing iron ore concentrates during the selective reduction volatilization process. In this study, natural calcite powders were added into the tin-bearing iron ore concentrates to investigate tin volatilization behavior affected by CaCO3 under different roasting temperature, CO content, and roasting time. In addition, the effect of CaCO3 on the phase transformation of SnO2 was determined using XRD, SEM-EDS combined with thermodynamics calculation. The results indicated that CaCO3 had a significantly adverse effect on the Sn volatilization ratio, because Ca2SnO4 was easily formed under CO-CO2 atmosphere. It was also found from the study that the generation of SnO(s) was the most critical intermediate for promoting the formation of Ca2SnO4.

Separation and recovery of iron and manganese from high-iron manganese oxide ores by reduction roasting and magnetic separation technique

ABSTRACT Sodium salts were used in the reduction roasting and magnetic separation process to separate and recover iron and manganese from the high-iron manganese oxide ores to utilize the complex ores. Results showed that Na2S2O3 was the most effective salt. A magnetic concentrate with 86.39 wt% TFe and 96.21 wt% Fe recovery as well as a nonmagnetic product with 54.84 wt% TMn and 85.96 wt% Mn recovery was obtained when the ore sample was reduced at 1100°C for 100 min in the presence of 7 wt% Na2S2O3. In addition, the effects of roasting and separation parameters on the recovery of manganese and iron and the function mechanism of Na2S2O3 were investigated.

Recycling of carbonaceous iron-bearing dusts from iron & steel plants by composite agglomeration process (CAP)

A composite agglomeration process (CAP) is carried out to recycle the carbonaceous iron-bearing dusts generated from the Iron & Steel companies in order to reduce the environmental pollution caused by the hazardous dusts and make good use of the valuable elements contained in the dusts. In current study, all the dusts are first made into green pellets and used as one part of agglomeration feeds. Effects of the properties of the pelletised feeds on the agglomeration indexes of CAP and the mineralisation, metallurgical characterisation of the CAP products were investigated. It is found that the dust dosage is increased from 7 wt.% by traditional sintering process to 20 wt.% by CAP. Coke breeze consumption is reduced by 21.25 kgcoke/tproduct in the CAP with 20 wt.% pelletised feed proportion, indicating the carbon component in the dusts is effectively utilised. The mineralisation characterisations of CAP products are clarified by using optical microstructure and SEM-EDS analyses. Results also demonstrate that metallurgical performances of the CAP products are good and the CAP products are qualified for blast furnace burdens.

Phase Evolution oF Tin Oxides Roasted Under CO–CO2 Atmospheres in the Presence of Na2CO3

ABSTRACT High-purity Na2SnO3 has been prepared by a novel process of roasting SnO2 and Na2CO3 in a solid state under CO–CO2 mixed gas. In the current study, the phase evolution of tin oxides and Na2CO3 roasted under various CO–CO2 atmospheres was investigated by chemical and X-ray diffraction analysis. Under the CO content of 5–20 vol% and temperature over 800°C, Na2CO3 can react with SnO2 and the intermediate products of SnO and Sn to form Na2SnO3. SnO would be decomposed into SnO2 and Sn at temperatures below 800°C; however, the decomposition reaction was effectively restrained by Na2CO3 over 800°C. Na2CO3 apparently inhibits the volatilization of SnO. The reaction mechanism of SnO and Na2CO3 under reductive atmosphere was clarified.

Research on Recovering Iron Oxide from the Iron, Tin-Bearing Tailings

Iron, tin-bearing tailings is a kind of hazardous solid waste generated from cassiterite dressing operation. It is difficult to utilize the tailings by present mineral processing methods due to the complex dissemination characteristics. In this study, a process of gas-based magnetizing roasting followed by magnetic separation was studied for separating and recovering iron from the tailings. The effects of roasting and magnetic separation parameters on the recovery of iron were systematically investigated. The optimum parameters were proposed as follows: CO/(CO+CO2) content of 5%, roasting temperature of 850 “C, roasting time of 60 min, grinding particle size of 90% less than 45 µm and magnetic field intensity of 800 Gs. Under these conditions, the magnetic concentrate containing 68.5% Fe and 0.06% Sn was achieved, which can be used as high-quality raw materials for direct reduction iron production.

Preparation and Characterization of NaNO 3 /BFS Composite Phase Change Materials

Blast furnace slag (BFS), one kind of typical solid waste in the steel industry, was used as structural materials to synthesize NaNO3/BFS composite phase change materials (C-PCMs) by mixing and sintering method. NaNO3 in the composites functioned as phase change materials (PCMs) and BFS as structural skeleton to maintain a stable external form. In this study, the prepared C-PCMs could remain in the solid state without salt leakage even if operating temperature exceeded the melting temperature of NaNO3. The composition and structure of BFS and the prepared composites were characterized by XRD, FTIR, SEM and TG-DSC analyses. The results showed that NaNO3 was well incorporated in the pores of BFS. The melting temperature and latent heat of the final composites were 300.5 °C and 65.53 J/g, respectively. The product also had good thermal storage performance and durability even after 100 thermal cycles. The energy density of the product was calculated as high as 468.03 J/g for an temperature range of 50–400 °C.

Rapid Removal of Pb(II) from Acid Wastewater Using Vanadium Titanium-Bearing Magnetite Particles Coated by Humic Acid

Acid wastewater containing toxic metal ions has become increasingly important global environmental concern and lead (Pb) is one of the prime toxic heavy metal ions. Humic acid (HA), a kind of natural organic matter, has been proven to have a great adsorption capacity for metal cations (Pb2+, Cu2+, etc.). Our previous study has verified that HA has excellent adsorbing ability on vanadium titanium-bearing magnetite(VTM) particles. In this study, VTM-HA complex magnetic particles were prepared for removing Pb(II) from acid wastewater, which could be easily recycled by magnetic separation. The effects of pH value, ionic strength and VTM-HA concentration on the removal ratio of Pb(II) were determined by isothermal adsorption tests. The results indicated that Pb(II) adsorption was subject to pH and ionic strength. When initial Pb(II) concentration is 100 mg/L, the residual concentration and removal ratio of Pb(II) reach 0.17 mg/L and 99.83%, respectively, which are much lower than the discharge standard.