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Wang X.,Chinese Academy of Sciences | Zhao B.,Chinese Academy of Sciences | Yuan X.,Chinese Academy of Sciences | Huang G.,Citic Dameng Mining Industries Ltd | And 3 more authors.
Chinese Journal of Environmental Engineering | Year: 2017

The hydrolysis of cassava biomass by sulfuric acid was investigated, including the roles of the sulfuric acid concentration, temperature, and amount of cassava biomass. The results show that cassava starch, cassava chips and cassava dregs as raw materials can provide reducing sugar yields of greater than 95%, 85%, and approximately 60%, respectively, under suitable conditions. Cost analyses show that the cassava dregs are the least expensive raw material per ton of reducing sugar produced. Cassava dregs were also used for the reducing leaching of manganese oxide ore, providing a manganese leaching rate exceeding 90%. © 2017, Science Press. All right reserved.


Ma H.-J.,Guilin University of Technology | Lu Y.-Z.,Guangxi University for Nationalities | Chen D.-L.,Guilin University of Technology | Ming X.-Q.,CITIC Dameng Mining Industries Ltd | And 4 more authors.
Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering | Year: 2015

Lactic acid was used to treat low grade pyrolusite for leaching of manganese. The effects of lactic acid amount, reaction time, leaching temperature and volume fraction of sulfuric acid on the leaching rate of manganese were examined by single-factor experiments. Response surface methodology was used to optimize the conditions of reductive leaching. The organic compounds in the reaction were detected by high performance liquid chromatography. The results show that when the pyrolusite ore is 10.0 g, the leaching rate of manganese reaches 93.99% under the optimal conditions of lactic acid 1.24 mL, reaction time 3.47 h, leaching temperature 90℃, volume fraction of sulfuric acid 12%, stirring speed 200 r/min and ratio of liquid to solid 10 mL/g. Acrylic acid, formic acid and acetic acid are generated in the oxidation of lactic acid. After the reduction leaching for 60 min, lactic acid reacts almost completely. During the reaction time of 210 min, the content of acrylic acid is not decreased obviously, but the content of formic acid and acetic acid increased slowly. © 2015, Science Press. All right reserved.


Chen N.,Citic Dameng Mining Industries Ltd | Xie L.,Guangxi Autonomous Region Bureau of Quality and Technical Supervision | Shu J.,Chongqing University | Li H.,Citic Dameng Mining Industries Ltd | And 2 more authors.
Huagong Xuebao/CIESC Journal | Year: 2016

High purity and heavy manganese carbonate was prepared via controlling crystallization in ammonia buffer system, with sodium carbonate and high purity manganese sulfate as the starting materials. When the concentration of MnSO4 and Na2CO3 solution was 1.5 mol·L-1, and Na2CO3 excess coefficient was 110% with adding rate of 120 ml·h-1 at pH 8.5 and 50℃, the apparent density of manganese carbonate was 1.67 g·cm-3 and tap density was 2.15 g·cm-3. Ammonia buffer system increased the stability of the solution, and suppressed the formation of manganese hydroxide and partial manganese hydroxide. The morphology of high density of manganese carbonate was spherical, and particle size with an average size (D50) of 30.32 μm distributed uniformly. Heating the manganese carbonate prepared in this study, the apparent density and tap density of obtained mangano-manganic oxide was 1.09 g·cm-3 and 2.18 g·cm-3, respectively. © All Right Reserved.


Wang L.,Taiyuan University of Technology | Chen J.,Taiyuan University of Technology | Hao J.-J.,Taiyuan University of Technology | Hao J.-J.,Shanxi Engineering Vocational Technology College | And 3 more authors.
Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering | Year: 2013

Medium and low-carbon ferrochrome powder containing CaO was obtained by fast solid-phase decarburization of high-carbon ferrochrome powder with CaCO3 by microwave heating. High-carbon ferrochrome powder with calcium carbonate was decarburized at 900, 1000, 1100, 1200°C for 60 min. The carbon content of decarburized material was measured. The microstructure and phase composition of this new metallurgical material were studied by metallography, electron probe and XRD phase analyzers, the carbon content and phases change during the solid-phase decarburization were also analyzed. The results show that carbon content of high-carbon ferrochrome powder was 5.06%, 2.24%, 1.71% and 1.39% at 900, 1000, 1100 and 1200°C. Compared with original carbon content of 8.16%, it was obviously reduced during the decarburization, carbon-rich carbide phase (Cr, Fe)7C3 changed gradually to metal-rich carbide phase (Cr, Fe)23C6 and ferrochrome ferrite phase CrFe; Coarse grain structure (Cr, Fe)7C3 changed to honeycomb dissolution structure (Cr, Fe)23C6 and granular encroach structure CrFe. Chromium oxides in the decarburized material were mainly Cr2O3, CaCr2O4 and CaCr2O7. Generally, the optimum conditions of solid phase decarburization were decarburization temperature of 1100°C and 60 min heating.


Li L.,Central South University | Li Y.,Central South University | Li Y.,Citic Dameng Mining Industries Ltd | Xu C.,Central South University | And 7 more authors.
Hydrometallurgy | Year: 2014

The potential-pH diagrams for lithium-titanium-water system at temperatures of 333.15, 363.15, 393.15 and 453.15 K and ion activities of 0.01, 0.1 and 1 of the dissolved species were constructed to predict the predominant areas of lithium-titanium composite oxides in the Li-Ti-H2O system. Empirical functions were applied to estimate the thermodynamic data, which are unavailable in the literature. The presented Eh-pH diagrams show that temperature and ion activity have significant effects upon the stable regions of various species considered in Li-Ti-H2O system. With an increase in temperature, or ion activity, the dominant regions of Li2TiO3(hc), Li 4Ti5O12(hc) and Li4TiO 4(hc) shift towards lower pH zones. Also, the predominant areas of Li4Ti5O12(hc) and Li2TiO 3(hc) shrink, while that of Li4TiO4(hc) enlarges. This demonstrates that the production of Li4Ti 5O12 and Li2TiO3 is thermodynamically feasible by a wet process. Experiments were subsequently performed in light of the constructed potential-pH diagrams. The results indicated that the potential-pH diagrams are consistent with experiment. Therefore, the preparation of Li4Ti5O12 and Li2TiO3 in aqueous solution is feasible and the process can be controlled in practice. © 2013 Elsevier B.V.


Li Y.-J.,Central South University | Li Y.-J.,Citic Dameng Mining Industries Ltd | Xu H.,Central South University | Xu H.,Citic Dameng Mining Industries Ltd | And 7 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2014

Spinel powders of Li1.035Cox Mn1.965-xO4(x=0-0.100) systems were synthesized by a simple wet chemical process with post heat-treatment. X-ray diffraction (XRD) patterns reveal that the Co doping does not affect the Fd3m space group of the cathode materials. Scanning electron microscope (SEM) images show that the Li1.035CoxMn1.965-xO4 cathode materials have a uniform and nearly cubic morphology with a narrow size distribution. Transmission electron microscope (TEM) results demonstrate that the Li1.035Co0.035Mn1.930O4 powder has a good crystalline state. The electrochemical testing results indicate that the prepared Co-doped Li1.035CoxMn1.965-xO4 samples show a better cycling ability and rate capability at room temperature than that of Co-free Li1.035Mn1.965O4. In particular, the Li1.035Co0.035Mn1.930O4 sample delivers a reversible specific capacity of 113 mAh/g in 1st cycle and retains 93.8% of its initial capacity after 100 cycles at 0.5C rate. When discharging at 4C rate, the Li1.035Co0.035Mn1.930O4 powder maintains 86 mAh/g, which is 76.1% of the reversible capacity at 0.5C. Comparatively, the Li1.035Mn1.965O4 powder maintains only 64.8% of its reversible capacity at 0.5C discharge rate. The electrochemical impedance spectroscopy results show that Co ion doping can enhance the electrical conductivity and the Li-ion diffusion coefficient. These results indicate a superior cycling and rate performance compared with the pristine one.


Li Y.,Central South University | Wang X.,Central South University | Ming X.,Citic Dameng Mining Industries Ltd | Xu C.,Central South University | And 4 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

Li4Ti5O12 precursor was synthesized by a wet chemical method in aqueous media using amorphous hydrated TiO2, which was prepared by hydrolysis method from TiCl4 aqueous solution. The effects of calcining temperature on the phase composition, morphology and electrochemical property of the products were investigated. The physical and electrochemical performances of Li4Ti5O12 were characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) and constant current discharge-charge measurement. The results indicate that the Li4Ti5O12 products synthesized by the wet chemical method followed by heat treatment at 750°C and 800°C have a good spinel structure. The sample calcined at 750°C for 6 h has a uniform particle size distribution, regular morphology, and shows the best electrochemical performance. The tests show that the as-prepared Li4Ti5O12 delivers the initial discharge specific capacity of 175.0 mA·h/g at 0.1C current rate in the voltage range of 1.0-2.5 V, and its discharge capacity reduces to 167.5 mA·h/g at 0.5C. The capacity decays to 163.0 mA·h/g after 60 cycles, and remains 97.3% of its initial specific capacity at 0.5C rate.


Kong L.,Central South University | Kong L.,Citic Dameng Mining Industries Ltd | Li Y.-J.,Central South University | Li Y.-J.,Citic Dameng Mining Industries Ltd | And 5 more authors.
Journal of Central South University | Year: 2014

A simple hydrothermal process followed by heat treatment was applied to the preparation of spinel Li1.05Mn1.95O4. In this process, electrolytic manganese dioxide (EMD) and LiOH·H2O were used as starting materials. The physiochemical properties of the synthesized samples were investigated by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffractometry (XRD), and scanning electronic microscopy (SEM). The results show that the hydrothermally synthesized precursor is an essential amorphous. The precursor can be easily transferred to spinel powders with a homogeneous structure and a regularly-shaped morphology by heat treatment. Li1.05Mn1.95O4 powder obtained by heat treating the precursor at 430°C for 12 h and then calcining at 800°C for 12 h shows an excellent cycling performance with an initial charge capacity of 118.2 mA·h·g-1 obtained at 0.5C rate and 93.8% of its original value retained after 100 cycles. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.


Kong L.,Central South University | Kong L.,Citic Dameng Mining Industries Ltd | Li Y.-J.,Central South University | Li Y.-J.,Citic Dameng Mining Industries Ltd | And 3 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2013

Spinel Li1.035Mn1.965O4 and Al-doped Li1.035Al0.035Mn1.930O4 cathode materials were synthesized by a simple wet-chemical technique and heat treatment. The structure and the morphology of the two samples were investigated by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD patterns show that both of the two samples exhibit a well-defined spinel structure. The TEM result demonstrates that the Li1.035Al0.035Mn1.930O4 powder possesses a good crystalline state. The galvanostatic charge/discharge tests indicate that the Li1.035Al0.035Mn1.930O4 material delivers an excellent cycling ability and a nice rate capability, maintaining 96.4% of its initial capacity after 100 charge-discharge cycles at 0.5C and keeping 79.6% of the reversible capacity at 0.5C discharge rate when discharges at 4C rate.


Li Y.,Central South University | Li Y.,Citic Dameng Mining Industries Ltd | Han Q.,Central South University | Han Q.,Citic Dameng Mining Industries Ltd | And 9 more authors.
Ceramics International | Year: 2014

A novel hydrothermal process followed by heat treatment was used for the preparation of the layered LiNi0.5Co0.2Mn 0.3O2 cathode materials for lithium ion batteries. The lithiated metal oxide precursor obtained from the hydrothermal process had a homogeneous distribution of metals and a weak crystallinity. The layered LiNi0.5Co0.2Mn0.3O2 powders were obtained by the post-heat treatment of the lithiated metal oxide. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma (ICP), atomic absorption spectroscopy (AAS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge testing. The cathode material with hexagonal α-NaFeO2 structure, low cation mixing, appropriate crystallinity and homogeneous spherical particles was obtained. The results indicated that the initial discharge capacities of the cathode material were 150 mAh g-1, 165.7 mAh g-1 and 184.8 mAh g-1 at the discharge rate of 0.5 C (100 mA g-1) with the cut-off voltage range of 3.0-4.3 V, 2.8-4.4 V and 2.5-4.5 V, respectively, and it retained 97.6%, 99.4% and 99.2% of the initial capacity after 50 cycles. It indicated that the novel hydrothermal lithiation followed by post-heat treatment is a promising route for the synthesis of LiNi0.5Co0.2Mn 0.3O2 cathode material with improved properties. © 2014 Elsevier Ltd and Techna Group S.r.l.

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