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Optimization of iron and aluminum recovery in bauxite

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Journal of Iron and Steel Research International 2020年第3期27卷 310-318页

作者： qian Long jun-qi li Chao-yi Chen Yuan-pei Lan Guo-ling Wei Department of Metallurgical Engineering College of Materials and MetallurgyGuizhou UniversityGuiyang 550025GuizhouChina Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025GuizhouChina

Recovering iron and aluminum efficiently is the key route to utilize low-grade high-iron *** to optimize the iron separating process and elevate both Fe and Al recovery ratio,three different Fe-Al recovery processes with different magnetic roasting(R),Bayer leaching process(L)and magnetic separation(S)orders were *** studied processes include bauxite leaching→red mud roasting→magnetic separation(L-R-S),bauxite roasting→magnetic separation→leaching(R-S-L)and bauxite roasting→leaching→magnetic separation(R-L-S).The iron recovery ratio,Fe2O3 content in iron concentration and the bauxite dissolution ratio of each process were ***,the optimizations of the leaching,roasting and magnetic separation conditions were *** indicate that the R-S-L process should be an advisable order to recover both alumina and *** the three processes,the R-S-L route had the highest alumina dissolution ratio and iron recovery ratio,which was 86.20%and 69.58%,respectively,while the Fe2O3 content of the iron concentrate was 40.66%.

关键词： High-iron bauxite Magnetic roasting Magnetic separation Recovery ratio Dissolution ratio

Suspension calcination and alkali leaching of low-grade high-sulfur bauxite:Desulfurization, mineralogical evolution and desilication

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 602-610页

作者： Hong-fei Wu jun-qi li Chao-yi Chen Fei-long Xia Zhen-shan Xie Department of Metallurgical Engineering College of Materials and MetallurgyGuizhou UniversityGuiyang 550025China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025China

To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.

关键词： low-grade bauxite sulfur suspension calcination alkali-soluble desilication Bayer process

Solid oxide membrane-assisted electrolytic reduction of Cr_(2)O_(3) in molten CaCl_(2)

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International Journal of Minerals,Metallurgy and Materials 2020年第12期27卷 1626-1634页

作者： Bo Wang Chao-yi Chen jun-qi li lin-zhu Wang Yuan-pei Lan Shi-yu Wang College of Materials and Metallurgy Guizhou UniversityGuiyang 550025China Guizhou Province Key Laboratory of Metallurgical Engineering and Process Energy Saving Guiyang 550025China

Solid oxide membrane-assisted electrolytic reduction of solid Cr_(2)O_(3) to Cr in molten CaCl_(2) was performed using a sintered porous Cr_(2)O_(3) cathode paired with an yttria-stabilized zirconia(YSZ)tube anode containing carbon-saturated liquid copper *** of the reduction mechanism,ion migration behavior,and effects of cathode pellet porosity and particle size on the electrolysis products and reduction rate revealed that the cathode microstructure and electrolytic conditions were key factors influencing the electrolysis *** results were obtained when the cathode was characterized by high porosity and a small particle size because this combination of features contributed to ion *** electrochemical activation was observed when cathode pellets prepared by 4 MPa molding followed by 2 h of sintering at 1150℃ were *** electrode reduction process(Cr^(3+)→Cr^(2+)→Cr)was promoted by high electrode voltages,and Cr metal was efficiently *** proposed method appears to be well suited for electrolytic Cr production because it does not require expensive pre-electrolysis techniques or generate harmful by-products.

关键词： solid oxide membrane yttria-stabilized zirconia electrometallurgy chromium molten salt

Image stabilization with support vector machine

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第6期12卷 478-485页

作者： Wen-de DONG Yue-ting CHEN Zhi-hai XU Hua-jun FENG qi li State Key Laboratory of Optical Instrumentation Zhejiang University Hangzhou 31002 7 China

We propose an image stabilization method based on support vector machine (SVM). Since SVM is very effective in solving nonlinear regression problems, an SVM model was constructed and trained to simulate the vibration characteristic. Then this model was used to predict and compensate for the vibration. A simulation system was built and four assessment metrics including the signal-to-noise ratio (SNR), gray mean gradient (GMG), Laplacian (LAP), and modulation transfer function (MTF) were used to verify our approach. Experimental results showed that this new method allows the image plane to locate stably on the CCD, and high quality images can be obtained.

关键词： Support vector machine (SVM) Vibration Displacement Prediction Compensation

Unraveling role of double-exchange interaction in electrochemical water oxidation by external magnetic field

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Rare Metals 2024年第1期43卷 289-297页

作者： jun li jun-Ming li Hong Hong Dong-Xue liu qing-qi Cao Dun-Hui Wang National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory for Nanotechnology Nanjing UniversityNanjing 210093China School of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China

Double-exchange(DE) interaction plays an important role in electrocatalytic oxygen evolution reaction(OER).However,precise achievement of DE interaction often requires foreign dopants or vacancy engineering,leading to destabilization of the catalysts and deterioration of *** contrast,the utilization of environmentally friendly,contactless,and continuously adjustable magnetic fields to study the OER process is profitable to avoid aforementioned interference factors and further elucidate the direct relationship_(0.5)between DE interaction and OER ***,by using cobalt hydroxide carbonate(Co(OH)(CO_(3))·xH_(2)O,CoHC) nanostructures as a proof-of-concept study,external magnetic fields are carefully implemented to verify the role of DE interaction during water oxidation *** studies reveal that external magnetic fields effectively enhance the reaction rate of the catalyst,the overpotential decreases from 386 to 355 mV(100 mA·cm^(-2)),while Tafel slopes drastically decline from 93 to 67 mV·dec^(-1)(1.0 T).Moreover,magnetic field increment exhibits robust *** in situ Raman and impedance measurements under external field,it can be found that magnetic field promotes the electron migration between Co^(2+) and Co^(3+) in the CoHC catalysts with the assistance of DE interactions,thus boosting the OER efficiency.

关键词： Magnetic field Double-exchange(DE)interaction Electrocatalysis Oxygen evolution reaction(OER) Cobalt hydroxide carbonate

Enhanced hydrogen evolution reaction in FePt film with remanence due to decrease in domain walls

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Rare Metals 2024年第3期43卷 1108-1115页

作者： Hong Hong Dong-Xue liu jun li jun-Ming li li-qian Wu Bo Yang qing-qi Cao Dun-Hui Wang National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresJiangsu Provincial Key Laboratory for NanotechnologySchool of PhysicsNanjing UniversityNanjing210093China Hangzhou Dianzi University Hangzhou310018China Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang110819China

As an effective strategy to improve the properties of electrocatalysts,magnetic field-assisted electrocatalytic water splitting has attracted increasing attention ***,the corresponding enhancements mostly depend on the exertion of an external magnetic field during electrochemical reactions,which results in a high cost of industrial production,and makes the magnetic field manipulation of electrocatalysis become a challenging *** this work,instead of the external magnetic field,a bias magnetic field is self-supplied by the remanence state of a ferromagnetic electrocatalyst of *** to the assistance of this bias magnetic field,the FePt film in the remanence state shows the overpotential of 229 mV during hydrogen evolution reaction,which is much lower than that in its demagnetization state(283 mV).Our findings demonstrate that the remanence in ferromagnetic electrocatalysts can improve the catalytic performance,which is attributed to the decrease in domain walls.

关键词： Remanence Magnetic domains Electrocatalysis Hydrogen evolution reaction(HER)

Novel linear search for support vector machine parameter selection

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第11期12卷 885-896页

作者： Hong-xia PANG Wen-de DONG Zhi-hai XU Hua-jun FENG qi li Yue-ting CHEN State Key Laboratory of Optical Instrumentation Zhejiang University Hangzhou 310027 China

Selecting the optimal parameters for support vector machine (SVM) has long been a hot research topic. Aiming for support vector classification/regression (SVC/SVR) with the radial basis function (RBF) kernel, we summarize the rough line rule of the penalty parameter and kernel width, and propose a novel linear search method to obtain these two optimal parameters. We use a direct-setting method with thresholds to set the epsilon parameter of SVR. The proposed method directly locates the right search field, which greatly saves computing time and achieves a stable, high accuracy. The method is more competitive for both SVC and SVR. It is easy to use and feasible for a new data set without any adjustments, since it requires no parameters to set.

关键词： Support vector machine (SVM) Rough line rule Parameter selection linear search Motion prediction

Special Issue:Dynamic Polymer Networks

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Chinese Journal of Polymer Science 2024年第10期42卷 1401-1402页

作者： jun-qi Sun Zhi-Bo li Tao Xie 不详

The ease of processing and light weight have made polymeric materials uniquely suited for numerous general ***,realization of their switchable chain configuration/mobility and molecular design versatility has pushed p... 详细信息

关键词： uniquely realization polymeric

The first catalytic asymmetric addition of diethylzinc to aldehyde promoted by chiral thiourea

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Chinese Chemical Letters 2011年第11期22卷 1265-1268页

作者： Zhi Guo qiao Tian Hua Shen Zhen Fang Fu jun qi li Hong Wang qing Bao Song The State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology College of Chemical Engineering and Materials Science Zhejiang University of Technology Hangzhou 310032 China

A series of C_2-symmetric and asymmetric chiral thiourea derivatives were synthesized from commercial *** of the new compounds have been fully characterized by IR,~1H NMR,^（13）C NMR,MS spectra and elemental *** chiral thioureas were used as chiral ligands in the catalytic enantioselective ethylation of aldehydes with diethylzinc,the corresponding sec-alcohols were gained with excellent enantioselectivities（up to 87.1%ee） and high yields（up to 76.7%） after the conditions were optimized.

关键词： Chiral thiourea Diethylzinc Amino alcohol C_2-symmetric Enantioselective addition