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Study on kinetics of thermal decomposition of low LOI goethetic hematite iron ore

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International Journal of Mining Science and Technology 2017年第6期27卷 1031-1036页

作者： Beuria P.c. Biswal S.K. Mishra B.K. Roy G.G. Mineral Processing Department CSIR–Institute of Minerals and Materials TechnologyBhubaneswar 751013India Indian Institute of Technology Kharagpur 721302India

In the present study, the kinetics of thermal decomposition of hydrated minerals associated in natural hematite iron ores has been investigated in a fixed bed system using isothermal methods of kinetic analysis. Hydrated minerals in these hematite iron ores are kaolinite, gibbsite and goethite, which contribute to the loss on ignition(LOI) during thermal decomposition. Experiments in fixed bed have been carried out at variable bed depth(16, 32, 48 and 64 mm),temperature(400-1200 ℃) and residence time(30,45, 60 and 75 min) for iron ore samples. It is observed that beyond a certain critical bed depth(16 mm), 100% removal of LOI is not found possible even at higher temperature and higher residence time. Most of the solid-state reactions of isothermal kinetic analysis have been used to analyze the reaction mechanism. The raw data are modified to yield fraction reacted "α" versus time and used for developing various forms of "α" functions.f(α) is the inverse of first derivative of g(α) with respect to α. The study demonstrates that decomposition of hydrated mineral in hematite follows the chemical *** estimated activation energy values in all the experimental situations are found to high, of the order of 60 kJ/mol, reinstating that the reactions are indeed controlled by moving phase boundary and random nucleation.

关键词： Loss on ignition Goethite Kaolinite Gibbsite Roasting Pellet feed Kinetic analysis

Liquid-liquid extraction and separation of total rare earth(RE) metals from polymetallic manganese nodule leaching solution

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Journal of Rare Earths 2015年第2期33卷 207-213页

作者： P.K.Parhi K.H.Park c.W.Nam J.T.Park Mineral Resources Research Division Korea Institute of Geoscience & Mineral Resources (KIGAM)Daejeon 305-350 Republic of Korea School of Applied Science and center of Industrial Technology KIIT UniversityBhubaneswar 751024 Odisha India

The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L cu, 0.2 g/L Fe, 0.01 g/L co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using ca（OH）2 at pH 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents（D2EHPA, Pc88 A, cyanex 272） were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. pH effect, the performances of above three extractants followed the order as： D2EHPA〉Pc88A〉cyanex 272. To ensure the absence of extraction of base metals（cu, co, Ni）, the eq. pH of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. pH with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EHPA. Extraction isotherm plot was constructed at A：O=12：1, 3-stages and pHe=2.21, using 0.8 mol/L D2 EHPA and the predicted condition of this study was further confirmed by 6-cycles counter current Simulation（ccS） study. The stripping of total rare earth from loaded organic phase（LO） was conducted using Hcl solution. Mc-cabe Thiele diagram study carried out at A：O=1：5 using 4 mol/L Hcl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction（SX） process.

关键词： total rare earth (RE) metals SX D2EHPA Hcl deep sea nodule

Physical properties of spray deposited cdTe thin films:PEc performance

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Journal of Semiconductors 2011年第3期32卷 10-16页

作者： V.M.Nikale S.S.Shinde c.H.Bhosale K.Y.Rajpure Electrochemical Materials Laboratory Department of PhysicsShivaji University

p-cdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical（PEc）,X-ray diffraction（XRD）,scanning electron microscopy,energy-dispersive analysis by X-ray（EDAX）,and optical transmission *** different preparative parameters viz solution pH, solution quantity,substrate temperature and solution concentration have been optimized by the PEc technique in order to get good-quality photosensitive *** analysis shows the polycrystalline nature of the film,having cubic structure with strong（111） *** reveal that grains are uniformly distributed over the surface of the substrate indicating the well-defined growth of polycrystalline cdTe thin *** EDAX study for the sample deposited at optimized preparative parameters shows the nearly stoichiometric cd：Te *** absorption shows the presence of direct transition with band gap energy of 1.5 *** films exhibit the highest photocurrent of 2.3 mA,a photovoltage of 462 mV,a 0.48 fill factor and 3.4%efficiency for the optimized preparative parameters.

关键词： cdTe PEc temperature concentration structure morphology composition optical

composition and phase structure dependence of mechanical and magnetic properties for AlcocuFeNi_x high entropy alloys

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Journal of Materials Science & Technology 2019年第6期35卷 1175-1183页

作者： cong Liu Wenyi Peng c.S. Jiang Hongmin Guo Jun Tao Xiaohua Deng Zhaoxia chen School of Materials Science and Engineering Nanchang University Nanchang 330031 China Institute of Space Science and Technology. Nanchang University Nanchang 330031 China

In this study, the effects of composition and phase constitution on the mechanical properties and magnetic performance of AlcocuFeNix(x = 0.5, 0.8, 1.0, 1.5, 2.0, 3.0 in molar ratio) high entropy alloys(HEAs)were investigated. The results show that Ni element could lead to the evolution from face centered cubic(Fcc), body centered cubic(Bcc) and ordered Bcc coexisting phase structure to a single Fcc phase. The change of phase constitution enhances the plasticity but reduces the hardness and strength. One of the interesting points is the excellent soft magnetic properties of AlcocuFeNixHEAs. Soft magnetic performance is dependent on composition and phase transition. AlcocuFeNi1.5 alloy, achieving a better balance of mechanical and magnetic properties, could be applied as structure materials and soft magnetic materials(SMMs). High curie temperature(>900 K) and strong phase stability below 1350 K of AlcocuFeNi0.5 alloy confirm its practicability in a high-temperature environment. Atomic size difference(δ) is utilized as the critical parameter to explain the lattice strain and phase transformation induced by Ni addition.

关键词： High entropy alloy Phase transformation Mechanical property Soft magnetic performance Atomic size difference

Understanding chemical Reactivity in Extended Systems：Exploring Models of chemical Softness in carbon Nanotubes

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物理化学学报 2018年第6期34卷 631-638页

作者： cáRDENAS carlos MUNOZ Macarena cONTRERAS Julia AYERS Paul W. GóMEZ Tatiana FUENTEALBA Patricio Departamento de Flsica Facultad de Ciencias Universidad de Chile Casilla 653 Santiago Chile centro para el Desarrollo de la Nanociencias y Nanotecnologia CEDENNA Avenida Ecuador 3493 Santiago Chile Nucleo de Matematicas Fisica y Estad

chemical reactivity towards electron transfer is captured by the Fukui ***,this is not well defined when the system or its ions have degenerate or pseudo-degenerate ground *** such a case,the first-order chemical response is not independent of the perturbation and the correct response has to be computed using the mathematical formalism of perturbation theory for degenerate ***-degeneracy is ubiquitous in nanostructures with high symmetry and totally extended *** the size of these systems,using degenerate-state perturbation theory is impractical because it requires the calculation of many excited *** we present an alternative to compute the chemical response of extended systems using models of local softness in terms of the local density of *** local softness is approximately equal to the density of states at the Fermi ***,such approximation leaves out the contribution of inner *** order to include and weight the contribution of the states around the Fermi level,a model inspired by the long-range behavior of the local softness is *** wall capped carbon nanotubes(SWccNT) illustrate the limitation of the frontier orbital theory in extended ***,we have used a c360 SWccNT to test the proposed model and how it compares with available models based on the local density of ***,a simple Hü ckel approximation captures the main features of chemical response of these *** results suggest that density-of-states models of the softness along simple tight binding Hamiltonians could be used to explore the chemical reactivity of more complex system,such a surfaces and nanoparticles.

关键词： Local softness Fukui function Reactivity carbon nanotubes Density of states

Influence of surface liquid segregation on corrosion behavior of semi-solid metal high pressure die cast aluminium alloys

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中国有色金属学会会刊：英文版 2010年第S3期20卷 837-841页

作者： E.P.MASUKU H.MLLER U.A.cURLE P.c.PISTORIUS Materials Science and Manufacturing Council for Scientific Industrial ResearchPretoriaSouth Africa Department of Materials Science and Engineering Carnegie Mellon UniversityPittsburghUSA

The corrosion behavior(in chloride medium) of the surface layer of SSM-HPDc plates of alloys 7075-T6 and 2024-T6 was compared with that of the wrought alloys 7075-T6 and *** testing was performed in deaerated 3.5%Nacl *** separate tests,the open-circuit potential was monitored in aerated 3.5% Nacl for 30 min after *** electrochemical tests show that there is no significant difference in the pitting potential of the wrought alloys and that of the cu-enriched surfaces of the SSM-HPDc alloys.

关键词： semi-solid metal(SSM) forming wrought aluminium alloys alloy 7075 alloy 2024 corrosion surface liquid segregation

MODIFIcATION OF SODIUM SALT OF PARTIALLY cARBOXYMETHYLATED TAMARIND KERNEL POWDER THROUGH GRAFTING WITH AcRYLONITRILE: SYNTHESIS, cHARAcTERIZATION AND SWELLING BEHAVIOR

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chinese Journal of Polymer Science 2013年第12期31卷 1670-1684页

作者： J.H.Trivedi J.R.Jivani K.H.Patel H.c.Trivedi P.G.Dept.of chemistry Sardar Patel UniversityVallabh Vidyanagar Amneal Phamaceuticals

A graft copolymer of polyacrylonitrile （PAN） with sodium salt of partially carboxymethylated tamarind kernel powder （Na-PcMTKP, DS ^-= 0.15） was synthesized by using ceric ammonium nitrate （cAN） as a redox initiator in an aqueous medium. The optimum reaction conditions for affording maximum percentage of grafting were established by successively varying reaction conditions such as concentrations of nitric acid, cAN, monomer （AN） as well as reaction time, temperature and amount of substrate. The influence of these reaction conditions on the grafting yields was discussed. The kinetic scheme of free radical graft copolymerization was proposed and the experimental results were found to agree very well with the proposed kinetic scheme. The graft copolymer （Na-PcMTKP-g-PAN, percentage of grafting G = 413.76% and percentage of grafting efficiency GE = 96.48%） sample synthesized under the established optimized reaction conditions was hydrolyzed by 0.7 mol-L l NaOH solution at 90-95 ℃ to yield the superabsorbent hydrogel, H-Na-PcMTKP-g-PAN. The swelling behavior of the hydrogel was studied by carrying out its absorbency measurements in low conductivity water, 0.15 mol·L^-1 salt （Nacl, cacl2 and Alcl3） solutions and simulated urine （SU） solution at different timings. FTIR, TGA and SEM techniques were used to characterize the products.

关键词： Sodium salt of partially carboxymethylated tamarind kernel powder Acrylonitrile Graft copolymerization Superabsorbent hydrogels Swelling behavior.

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Preface

chinese Journal of chemical Engineering 2018年第11期26卷 I0003-I0003页

作者： GW stevens Jinlong Gong The University of Melbourne Tianjin University

climate change is perhaps the most important challenge facing the world today and case for limiting cO2 emission into the atmosphere now is *** emissions of cO2 are linked to the use of fossil fuels for energy,transport and material utilisation and is a key technical challenge for the immediate *** the Paris Accord and all of the road maps produced to achieve stable cO2 emissions,for example from the International Energy Association,show no one technology can produce the changes required in the time required and the range of technologies are necessary to meet the goal of cO2 stabilisation to limit temperature rise to less than 2℃.One key technology that all of these road maps rely on is carbon capture,utilisation and storage (ccUS).The reason for this is that in some areas other technologies,such as renewables cannot be deployed in time in all sectors,for example in *** production of cO2 in many industrial applications,such as cement manufacture,are unavoidable and if the cO2 can be captured and reused or stored it offers a viable strategy to significantly reduce emissions,carbon capture from bio sources to produce energy with the cO2 stored offers one of the few negative emission technologies available that is economic today.

关键词： climate change Preface cO2

A dynamic two-zone model of continuous fluidized bed layering granulation with internal product classification

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Particuology 2017年第2期15卷 8-14页

作者： c. Neugebauer S. Palis A. Buck E. Tsotsas S. Heinrich A. Kienle Otto yon Guericke University Universitatsplatz 2 D-39106 Magdeburg Germany Max Planck Institute for Dynamics of complex Technical Systems Sandtorstraβe 1 D-39106 Magdeburg Germany Hamburg University of Technology Denickestraβe 15 D-21073 Hamburg Germany

A dynamic two-zone model is proposed to address the formation of granulation and drying zones in fluidized bed layering granulation processes with internal product classification. The model assumes a constant volume for the granulation zone, but a variable overall volume for the fluidized bed to account for classified product removal. The model is used to study the effect of various process parameters on dynamics and process stability. Stability is shown to depend on the separation diameter of product removal and the flow rate of the injected liquid. A lower and upper range of separation diameters with stable process behavior are found. In an intermediate range instability in the form of self-sustained oscillations is observed. The lower stability boundary is in qualitative agreement with recent experimental observations （Schmidt, Bück, ＆ Tsotsas, 2015）; the upper boundary was reported in a theoretical paper by Vreman, Van Lare, and Hounslow （2009） based on a single zone model.

关键词： Layering granulation Zone formation Internal product classification Population balance modeling Stability analysis