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By Edmundo Manilla, Merete Tangstad, Daniel Davila, Eli Ringdalen

FeMn alloys are typically produced with lumpy ore or sinters. Minara Autlan, the Mexican FeMn producer, is however making Mn-nodules as a raw material for Mn-alloy production. The Mn nodules have been characterized by XRF, XRD, by wet chemical methods and by EPMA. The Mn/Fe ratio is somewhat lower compared to commercial Mn ore on the marked. The basicity of the ore is however close to 1, and additional fluxes may not be used. The Mn-nodules will be in a state of manganosite (MnO), tephroite ((Mn, Ca)2SiO4) and galaxite ((Mn,Mg)Al2O4). This leads to a low melting temperature area. A low porosity and low amount of higher Mn-oxides gives a high thermal strength to the nodules.

Jan 1, 2016

By Alicia E. Ares, Carlos E. Schvezov

In the present work it was observed the nucleation and growth of grains in the equiaxed zone of metal matrix composites (MMCs) samples directionally solidified wit the presence of columnarto- equiaxed transition (CET) in the samples. In order to do so, first, it was defined the difference between the real temperature at a given instant, which it is used in the analysis, its variation and furthermore, the variation in the solid fraction with time between the beginning and the end of solidification. It was determined a growth law assuming a lineal variation of equiaxed grain radius as a function of time, and also, it was expressed a law of grain density as a function of time, considering the presence of SiC and Al2O3 particles in the matrix. Finally, the results obtained were validated with measured values of grain density at each position of the thermocouples in the equiaxed zone of the solidified samples.

Jan 1, 2015

By Liang Wang, Sheng-Kai An, Bing Xie, Hong-Yi Li, Cui Li

In order to develop an environment-friendly method for extracting vanadium effectively from aqueous solution containing vanadium, the dynamic adsorption behavior of V by a continuous fixed-bed column which was filled with macro-porous weak base anion exchange resin was studied. Effects of conditions including the bed depth, flow rate, concentration of vanadium ions on dynamic V adsorption were investigated. The optimum adsorption conditions were established at flow rate of 6 ml/min with bed depth of 20 cm. Isotherms studies demonstrated that the column adsorption of V was a favorable chemical ion exchange process in monolayer. Several kinetic models were applied to analyze the adsorption characteristics. Analysis results of the Bohart-Adams model indicated that the adsorption process was dominated by external mass transfer in the initial stage. The Thomas model was appropriate to describe the column behavior, revealing that both external and internal diffusions were involved in the limiting steps.

Jan 1, 2014

By J. -E. Eriksson, L. Hupa, T. Khazraie

With increased co-firing of coal and different biomasses in power plants, there is a growing need to study and characterize the produced, often heterogeneous ashes and to assess their utilization as secondary raw materials. In this work, we compare different methods for characterizing the ash compositions. These methods include scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS), X-ray fluorescence (XRF) and inductively coupled plasma emission spectroscopy (ICP-OES). The content of carbonaceous residues in the ashes was measured with CHN Sanalyzer. The methods and the pretreatment required for each of the analysis were studied in detail for three ashes: (1) coal, (2) peat and wood, (3) peat and wood residue with dolomite addition. The limitations of each method will be discussed. This work gives guidelines for selecting a rapid and reliable method for analyzing the suitability of the ash for a particular application.

Mar 1, 2018

By Yun Guo, Min-Min Lin, Bing Xie, Hong-Yi Li

The extraction of vanadium from vanadium-containing APV-precipitated wastewater by W/O microemulsion system was studied. In the N263/n-heptane/isoamyl alcohol/NaCl microemulsion system, N263 played double functions of cationic surfactant and extractant to form microemulsion in n-heptane, and isoamyl alcohol was added in the microemulsion as a cosurfactant. The extraction of vanadium by W/O microemulsion systems effectively accelerated the extraction and improved the extractatability because of the enormous increase in the micro-interfacial surface area. Due to ion association with extractant, vanadium was extracted into the microemulsion phase. The influence of different parameters on the extraction ratio (E%) were investigated, including the volume ratio of aqueous phase to microemulsion, surfactant concentration, pH value of the feed solutions, cosurfactant concentration, extraction time as well as temperature. In optimum conditions, the extraction ratio (E%) can reach 97.2%.

Mar 1, 2018

By Jian Pan, Deqing Zhu, Benjing Shi, Yuxiao Xue

COREX smelting reduction process which is freed of metallurgical coke provides a sustainable developing way for ironmaking industry. However, the shortage and high cost of pellets limit its development in China. Meanwhile, iron ore sinter has a great output in China. This work studied the reduction behaviors of sinter made from magnetite concentrates during the reducing process of COREX shaft furnace and compared the RI and RDI of sinter with BF process. The results showed that the reduction degree of sinter increased obviously during the temperature zone from 600 to 850 °C, while the reduction degradation presented rapidly aggravate in the temperature zone from 425 to 550 °C in COREX shaft furnace, and the increase of metallic iron content leads to the degradation of sinter got decreased slightly during the stage of temperature above 650 °C. Sinter got higher RI than BFprocess but also got higher RDI in low reduction temperature of 550 °C, which means sinter would have heavier disintegration in COREX shaft furnace.

Mar 1, 2017

By M. Moinpour, E. Liao, C. Y. Aw, D. J. Brown, P. W. Cheung

"Currently, silicon-based insulated-gate field-effect devices are being widely developed as the basic structural elements in a new generation of chemical microsensors. In this paper, we discuss some of the process considerations related to the fabrication of the Chemically Sensitive Field-Effect Transistor (CHEMFET). This ion-sensitive CHEMFET (or ISFET as it is often called) can be used for pH measurements (i.e., as a pH sensor) when the gate insulator of the electrolyte/insulator interface is made of Si3N4 obtained by the LPCVD method. Effects of processing parameters such as the Si3N4 deposition rate, gas composition, total flow rate, annealing treatment, etc. on Si/Si02, Si/Si3N4 and Si/Si02/Si3N4 structures are discussed in relation to the CHEMFET fabrication. Their effects on the electrical characteristics and chemical response of the sensor are also examined. Capacitance-Voltage (C-V) measurements and ESCA analysis have been used to interpret the results. The Si3N4/Si02 double dialectric layer provides improved ion blocking for the gate insulator in electrolyte solutions with enhanced pH sensitivity over time. The stability and performance of the fabricated CHEMFET sensors were tested by measuring the pH sensitivity in various storage conditions. The SEM analysis was used to evaluate the hydration effect at the ISFET's gate insulator with respect to different storage conditions.IntroductionThere has been a continuous interest in the development and fabrication of various chemical microsensors for chemical and biomedical applications over the last fifteen years. The application of semiconductor (particularly silicon) technology to the area of sensor fabrication has led to an emergence of a new generation of miniaturized, microelectronic, solid-state chemical sensors. There are numerous clinical situations where continuous monitoring of body electrolytes concentrations such as Na+, K+, Ca+2 , etc. and blood gases (pH, Po2 , and PC02) would be essential for the effective diagnosis and management of patients under critical conditions. Solid- state microsensors can be used for direct and continuous in vivo measurement of the above parameters in most instances."

Jan 1, 1988

By Robert W. Bartlett

"Economic and other factors, mostly outside of metallurgy, that strongly influence applied research, development and especially successful commercial adoption of new processes for producing primary metals and other commodity materials are reviewed. These factors, which can be both positive and negative in their influence, are often too lightly regarded in the research planning stage. They include continuing imperatives that have long influenced new process development as well as more recent trends. Both are discussed. Nearly all new materials eventually become commodities--products made to standard specifications with no producer control over price. Success requires being a low cost producer on a world wide basis. Composites and other complex material assemblages are unlikely to escape this fate as they mature.INTRODUCTIONThe adoption of new processes, beginning with research and development, for primary metals and other commodity materials is particularly difficult because each new process must supplant an existing process that is already being used commercially. There are many requirements besides technical innovation and cost superiority that must be met by the new process. Consequently, few innovations make it all the way from the research laboratory to commercial success.This paper discusses some of the factors that influence success in developing new processes for primary metals and commodity materials, based on the authors experience as a research metallurgist and industrial research manager. It begins with some of the factors that are always present and constrain successful process research and development, and proceeds to current trends that are expected to continue long enough to influence processes in the year 2000. Many of these trends are contradictory in their effect on new process development, and the future remains uncertain.The prevailing importance of these trends will vary with the material, process concept and other factors intrinsic to each case. Nevertheless, an awareness of these influences can help to avoid some of the R&D pitfalls and dead ends. Such awareness is deemed to be a necessary condition to avoid failure when commercial adoption of a new process is the goal."

Jan 1, 1988

By Bohumir Jelinek, Sergio Felicelli, Mohsen Eshraghi

"We present a parallel lattice Boltzmann - cellular automaton model of the two-dimensional dendritic growth during solidification of binary alloys. The model incorporates effects of solute and energy transport under melt convection. The parallel performance of the algorithm is assessed. A loss in the parallel efficiency is observed when multiple computational cores per processor are utilized. Excellent strong scaling up to thousands of computing cores is obtained across the nodes of a computer cluster, along with the near-perfect weak scaling up to forty thousand cores. The presented solidification model shows a good scalability up to centimeter size domains, including millions of dendrites.IntroductionLattice Boltzmann method (LBM) is an attractive numerical technique for solving fluid dynamics problems. Its advantages are simple formulation and locality, with locality facilitating parallel implementation. In the present model, interface kinetic is driven by the difference between local actual and local equilibrium liquid composition [1]. The cellular automaton (CA) technique is deployed to track the solid-liquid interface [2]. A serial version of the present LBM-CA model with a small number of dendrites was validated against theoretical and experimental results in the previous publications [3, 4]. In this work, it is the first time that simulations with millions of dendrites were performed, something not possible with the computationally much more costly phasefield method [5].This research effort examines a technique for simulations of millions of dendrites in centimeter size domains, including thermal, convection, and solute redistribution effects. Nearly ideal scaling properties of the model are demonstrated. This extensively large landmark was achieved because of• the CA technique being two orders of magnitude faster than alternative, phase-field methods [5]• highly parallelizable LBM method, convenient for simulations of flow within complex and time dependent boundaries• availability of the powerful NSF Extreme Science and Engineering Discovery Environment (XSEDE) supercomputing resources"

Jan 1, 2013

By Deventer Johanna van

Ore bodies around the world are declining in grade, whilst increasing in complexity. The level of impurities relative to the valuable metal is steadily increasing, posing new challenges to existing operations. Ion exchange is widely used in the hydrometallurgical industry for both primary recovery of metals and the removal of impurities. The superior selectivity of ion exchange resins makes them exceptionally suitable for the removal of target impurities to very low levels, thereby saving operating costs, increasing the value of the final product and significantly improving revenue. The ion exchange process in these applications is very simple, using standard ion exchange equipment and acid regeneration. The process can be fully automated, requiring minimal operator interference and supervision Examples of impurities that are successfully removed via ion exchange include iron, antimony and bismuth from copper electrolyte. In the copper electrolysis process, antimony, bismuth and arsenic tend to form slimes which are dispersed in the electrolyte. These slimes contaminate the cathode and/or decrease the quality of the copper deposition. A special chelating resin was developed to remove antimony and bismuth, while at the same time ensuring minimal chloride leakage to the sulphate matrix. The work is described in more detail in this paper. Ion exchange is also used to remove copper, zinc and nickel from cobalt electrolyte. This paper addresses a few of these examples in more detail.

By Takashi Fujii

In the OG (Osaka Gas) process which includes a fusion process of sewage disposal sludge in coke bed knowledge of molten and fluid properties of the sludge are most important to controll the process in good condition. Thus, the softening and melting temperatures and viscosity were measured by the sessile drop technique and a rotating viscometer. Obtained results are summarized as follows: Melting character of sludge slag is varied according to their composition, but closely related to CaO/SiO2 ratio in ordinary sludge and to CaO/(Cr2O3,+Al2O3+P2O5) ratio in Cr2O3 containing sludge. Fluid property of sludge slag has a correlation with optical basicity or Riboud parameter, However, the correlation is poorer than that of metallurgical slags. Especially, chromium oxide containing sludge shows high viscosity and behaves somewhat different manner from ordinary sludge.

Jan 1, 1992

By Norimasa Yamasaki, Masao Kurosaki

"The effects of plating conditions on the crystal orientation of electrodeposited zinc were investigated by varying elecyrolyte flow rate and current density. Precipitation of the Zn (00 • 2) basal plane is promoted at lower current density and higher flow velocity. Effect of the flow velocity on the mass transport was evaluated based on the polarization measurement in which Cu was used as the tracer. As a result, it has been clarified that the crystal orientation of electrodeposited zinc can be uniquely arranged by the overvoltage (iU0.5) that can be simply calculated by considering -the current density and boundary layer thickness. At the same time, the electrode potential during electrodeposition that can be calculated by using a model based on the competitive reactions of hydrogen reduction 'and zinc reduction exhibits an extremely good correlation with the crystal orientation of electrodeposited zinc.Introduction Electrogalvanized steel sheet has better surface properties than hot-dip galvanized steel sheet, and is used in home electric appliance and automobile applications. Factors such as crystal morphology, crystal orientation and surface roughness have a large influence on its appliance, formability and corrosion resistance [1-3].Electrolysis, condition, bath composition and alloying elements are reported as factors that affect the crystal orientation of the electrogalvanized coating. Factors that can be controlled on time in the production site are electrolysis condition that-is current density and plating solution flow velocity.Some studies[4-6] report that the crystal- orientation of the Zn(00 • 2) plane is increased by promoting, the mass transfer of zinc ions in the plating solution or decreasing the concentration overvoltage, but did not investigate in detail the plating solution flow conditions in the plating cell nor quantitatively determine the effects of both current density and plating solution flow conditions on the crystal orientation of ' electrodeposited zinc."

Jan 1, 2000

By K. V. Sreenivas Rao

Solidification experiments have been conducted to study the effect of interface heat flux and air gap formation on cooling rate of the casting during solidification of Al-4.5wt%Cu alloy. The thermal history of the casting and mold during solidification is recorded using thermocouples connected to computer interfaced data logger. The measured temperatures in the mold are used as input to the IHCP (inverse heat conduction problem) algorithm for simulating multiple heat flux components at the boundary. It is observed that the filling effects induce spatial variation in the thermal field in the mold and casting regions and greatly influence the cooling rate of the casting. The study demonstrates the use of IHCP and in-situ measured thermal profile in analyzing the cooling rate and microstructure.

Jan 1, 2008

By Liang Li

Thermodynamic analysis and experiments were conducted in order to verify the feasibility of preparing crude titanium tetrachloride (TiCl4) via the carbochlorination of low-grade titanium slag in molten salt. Titanium slag, assaying 74.6 wt% TiO2 with high calcium and magnesium oxide impurities, was treated by an optimized carbochlorination process in NaCl molten salt. These impurities in the titanium slag were chloridized simultaneously, and chlorination products FeCl2, MnCl2, MgCl2, CaCl2 and CrCl3 were collected in the furnace slag. XRD and SEM/ EDS analysis of residue shown that SiO2 and Al2O3 in titanium slag were difficult to chlorinate completely. Theoretical calculations and industrial-scale experimental studies reveal the content of TiCl4 in the products was more than 98.8 wt% and thus proved the feasibility of utilizing low-grade titanium slag for TiCl4 preparation by molten salt chlorination technology.

By Junbiao Liu

Rutile is mostly produced from placer sands. Its beneficiation from primary deposits has rarely been investigated. However, there is interest in primary deposit because of the depletion of sand deposits. The Zaoyang deposit in China is the only rutile primary deposit currently mined. The plant employs a Tabling-Magnetic process which recovers only 20% Ti02 at a grade of 87%. This study shows that significant improvement on the recovery (52% at the same grade) can be achieved. This study includes a detailed mineralogical examination and the development of a processing flowsheet of the ore. The gangues are primarily amphiboles, garnets, zoisites, and chlorites. The liberation of rutile occurs at about 200 mesh. Gravitational, flotation, and magnetic separations are all employed in the process developed, depending on the mineral characteristics and experimental results. The flotations circuit utilizes benzyl arsonic acid to float rutile and sodium fluosilicate to depress the gangues. This is a new reagent scheme for rutile flotation.

Jan 1, 1989

By Baokuan Li, Fang Wang

"Comparing with the single electrode in electroslag remelting processes, two series-connected electrodes have the advantage of little inductance, lower power consumption and higher melting rate, which was widely used to produce superalloys and specialty steels. Detailed understanding of the electromagnetic field distribution is essential for both improving ingot quality and saving electric energy. In the present work, a 3D finite element model was developed for the magnetic field, electromagnetic force, current density and Joule heating field of electro slag remelting processes (electrode, slag and ingot) with two series-connected electrodes using Maxwell equation, Lorentz law and Joule law. The results show that the maximum current distribute occur at the middle of electrode, due to the interaction of selfinduced and mutual-induced of two series-connected electrode; associated magnetic flux density on the inner side of electrode increase and the outer decrease; The maximum joule heating is at the interface of slag and electrode. The parameter study shows that if the current frequency is greater than 35Hz, the current density in inner electrode tend to linear distribution; with the increasing of original current, The maximum current density near the wall in electrode will increase linearly; with the increasing of electrode innnersion depth and decrease of slag cap thickness and the maximum of the joule heat in slag will increase.IntroductionElectroslag remelting processes(ESR) are widely used to produce superalloys and specialty steels [l-3l_Two pair, four pair or six pair electrodes in electroslag remelting processes is common in casting large scale ingot, which has the advantage of little inductance, lower power consumption and higher melting rate, comparing to singe electrode. They have the same essence with two electrodes in ESR.Compared to the single electrode ofESR, the other electrode is added which can decrease the reactive resistance and power consumption in the two electrodes of ESR. It is a complicated metallurgy process with a series physical and chemistry phenomenon from the molten of steel to the solidification of ingot [4-71_ These physical and chemistry phenomenon originated the effect of alternating current of high intensity. The rule of the alternating current of high intensity which revealed the law of physical and chemistry phenomenon in ESR is the precondition of improving ingot quality and saving electric energy. Jihe Wei and Yongli Ren[S-9lstudied the distribution of electromagnetic field in single electrode ofESR with Maxwell equation and relative electromagnetic theory. It had the limitation that take the electrode and mold as infinite conductivity. A detail analysis of Electromagnetic fields in ESR had been conducted by Patel A D [JO-llJ using general stream-function formulation. It is difficult to extend to three dimensions which could not be used widely. Daniel V [lZJ and Kharicha A [BJ only analysis the current density associated magnetic flux density field and temperature field without the whole irlformation of electromagnetic field. Maopeng Geng [l4J considered the current density and temperature field of the real and fake electrodes in ESR without skin effect. As to the complication of the two electrodes of ESR, it is rarely reported the electromagnetic field and Joule heating field of the two electrodes in ESR. The rule of effect of electromagnetic and modification of numerical simulation should be studied in depth."

Jan 1, 2011

By C. L. Lin

Multiphase, irregularly-shaped randomly-oriented PARGEN particles were grown to determine the breakage/liberation characteristics of such locked particles. The simulated locked particles were randomly broken to establish the liberation characteristics of the broken fragments. The progeny size distributions are consistent with Gilvarry's volume and surface flaw model for single particle breakage. The extent of liberation of both continuous and dispersed phases can be described from the conservation of interfacial area. In this regard the data can be normalized and liberation described for a wide range of dispersed phase grades and dispersion densities.

Jan 1, 1988

By Hwa-Soo Park, J. K. Yoon, Hoseok Nam

In a thin slab casting process, control of fluid flow in mold is particularly difficult due to the high casting speed and large aspect ratio of the mold and the understanding of the fluid flow motion as well as heat transfer in mold is regarded as the most important information because the melt delivery is directly related to the problems of shell growth nonuniformity, surface turbulence and mold powder entrapment. A mathematical model has been developed for the coupled analysis of fluid flow, heat transfer and solidification in funnel type mold using finite volume method based on a body fitted coordinate and the characteristics of the transport phenomena in the mold of thin slab caster were analyzed by numerical simulation. As a result of simulation, the basic flow pattern is characterized as four large recirculations and two small eddies near the narrow faces of mold, which is somewhat different from that of parallel type mold or other conventional slab caster. The heat transfer model accurately predicted the mold positions susceptible to cracking as a result of thermal stress and the predicted shell thickness shows good agreements with the measured shell thickness on breakout products. We also investigated the influences of some operation parameters such as casting speed, nozzle type, submerging depth and mold material on fluid flow, heat transfer and distribution of solidifying shell and various information for the determination of optimal operating conditions were obtained.

Jan 1, 2000

By Mark Cross, Andrew P. Campbell, Koulis A. Pericleous

"Computational Fluid Dynamics (CFD) modelling is being used to simulate the freeze layers formed within direct smelting processes. There has been some concern whether water-cooled elements can withstand the p~ocess conditions and in particular abnormal cases where they may be splashed in molten metal.To validate the models being developed, two cases from literature have been modelled for solidification and stress analysis. The solidification case is presented in detail and is for hot molten metal flowing through a cylindrical pipe. The walls are at a temperature below the melting point for the metal. The resulting solid (or freeze) layer is within 3% of the value calculated by Sampson & Gibson9 •Preliminary modelling of the refractory-slag interactions is presented. Although three basic mechanisms: Penetration; Corrosion; and Erosion will eventually be modelled, only the penetration is considered here. The corrosion mechanism is to be modelled by tracking the time that the penetrated refractory is at the required temperature.Future work, after adding all the required physics, will focus on the modelling of a water-cooled element placed lower in the smelter. Process perturbations will be simulated to examine what these elements will withstand."

Jan 1, 2001

By Robert Matusewicz

Ausmelt Technology has been applied to the recycling of spent pot liner (SPL) generated from primary alnminum production. The process is centered on the Ausmelt furnace, in which the SPL is converted under high temperature, oxidizing conditions to an HF containing gas stream and inert slag. fluorine is recovered from the SPL as HF gas and is concentrated and used to manufacture AIF) for recycle to the aluminum smelters. Approximately 87% of the fluorine can be recovered and converted to AIF), with the remainder being effectively tied up in the by product slag. Cost projections show that the recycling process will be competitive with other processes for SPL. The production and recycling of AIF) provides available credit that significantly offsets the operating cost of the facility. Ausmelt Technology for recycling of SPL is currently being marketed in North America by Ausmelt Technology Corporation in Denver, Colorado, and in the rest of the world by Ausmelt Limited of Dandenong, Australia.

Jan 1, 1996