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By L. Lewczuk

A detailed mineralogical and liberation study was performed on the iron ore mill products from the Scully concentrator of Wabush Mines, Newfoundland. Automated image analysis techniques were applied to deter-mine grain size distribution and liberation of all mineral components of the ore. As a result of the study it was indicated that iron recovery can be improved and the Mn minerals reduced in the iron ore concentrate by (a) increasing spiral middlings, (b) regrinding the middlings, and (c) separating the Mn minerals from the iron minerals in the reground middlings.

Jan 1, 1988

By Liu bing-guo, Peng Jin-hui, Guo Sheng-hui, Kong dong-cheng, Hu jin-ming, Zhang Li-bo

The novel technology of calcination to prepare triuranium octaoxide（U3O8）from ammonium uranyl carbonate in microwave fields was investigated on the basis of the temperature rising characteristics of ammonium uranyl carbonate, triuranium octaoxide (U3O8), and their mixture. The result of experiments show that ammonium uranyl carbonate had weak capability to absorb microwave energy, while triuranium octaoxide has the very strong capability to absorb microwave energy and the sample temperature increased rapidly with an increase mixture ratio of triuranium octaoxide. The optimal calcination conditions were as follows: microwave power 700 W, calcination time 10 min and 60 g in this experiments range, respectively. Under these conditions the value of total uranium and 4 U of triuranium octaoxide was 84.28% and 31.02%, respectively. It is feasible to prepare triuranium octaoxide by calcination from ammonium uranyl carbonate, which mixed with small amounts of triuranium octaoxide under microwave fields.

Jan 1, 2015

By T. Ahokainen, J. Pitkälä, J. L. Xia, A. Jokilaakso, J. Vaamo

"The aim of the present paper is to use the two CFD codes to model the two phase flow in a water model ladle with central gas injection. The codes examined are CFX and Phoenics. An Eulerian two phase model is used and predictions are compared against the experimental data available. The results show that the codes can reasonably well predict the gas-liquid plume in the ladle, and predictions are generally in a good agreement with experimental data. However, differences do exist in predicting the gas volume fraction and velocity profiles. The results should be interpreted most carefully and cautiously, because they are very sensitive to the boundary conditions and dependent on the models for the physical phenomena involved. IntroductionSubmerged gas injection has widely been used in the metallurgical industry for more than a century. At the present, the use of gas is most effective in steelmaking industry where the advantages of the gas injection have already been long well understood. Effective mixing, large contact area between reactants, easy modifications and flexibility of the processes are the most important advantages. Disadvantages include refractory wear, blocking in the tuyeres, and splashing. These disadvantages can be reduced and advantages further improved by studying the flow phenomenon in process vessels. However, it is difficult to study flow in a real vessel because of the high temperatures and physical and mathematical modelling is therefore increasingly used in the process development work."

Jan 1, 1999

By Hector Carreon

This paper presents experimental data for the magnetic field produced by thermoelectric currents around uncracked hard-alpha inclusions in a Ti?6Al?4V specimen under external thermal excitation for different nitrogen content ranging from 1.6% to 5.9%. According to our preliminary results, the magnetic flux density measurements were found to be rather sensitive to changes in nitrogen content with the exception of the intrinsic material background magnetic signal that affected deeply the detectability of inclusions and imperfections in non-contacting thermoelectric measurements. Hopefully, these preliminary results can help identify a non-destructive test method that can detect material inclusions with a level of nitrogen that could be detrimental to Ti?6Al?4V alloy components.

Jan 1, 2009

By Youn-Bae Kang, Jong-Jin Pak, Min-Kyu Paek

The critical evaluation and thermodynamic optimization of Mn-Si-C and its sub-binary systems have been carried out over the whole composition range from room temperature to above the liquidus temperature. The solution properties of the liquid systems have not been clearly described because the liquid solution exhibits a high degree of short-range-ordering. In order to predict the thermodynamics of the liquid solution, the liquid phases were optimized by the modified quasichemical model. The model parameters of the solid phases were also optimized by the compound energy formalism to best reproduce the phase diagram and important thermodynamic properties in Mn-Si-C system. Using the model parameters, various thermodynamic calculations were carried out. The present database will be a part of larger thermodynamic database for the ferromanganese alloy database.

Jan 1, 2014

By Jun Sugiyama, Hiroyuki Sano, Toshiharu Fujisawa, Hideki Takeuchi, Chikabiuni Yamauchi

"The solid .state electrotransport (SSE) is one of the most promising methods for the elimination of gaseous impurities from chemically active metals, such as rare earth metals. . In the present work, the SSE process was applied for the oxygen removal from praseodymium. The SSE factors, such as effective valence, were measured under the various temperatures, electric field intensities and initial oxygen contents, and the effects of those conditions on the SSE process were discussed. Furthermore, the solubility of oxygen in .solid praseodyillium was also measured·, by using the SSE method and metal-oxide equilibrium method.IntroductionWhen a direct current is passed through a solid alloy, not only electrons but also solute atoms are transported as charge carriers toward the anode or cathode. This phenomenon is referred to as an electrotransport or electromigration. The solid state electrotransport (SSE) is the application technique, based on this principle, to the pUrification of the solid metallic materials.Rare earth metals are used for various functional materials, such as magnetic, optical or electronic materials, therefore their high purity metals are required [l ,2]. However, rare earth metals are chemically active and have a strong affinity with gaseous elements (e.g. oxygen, nitrogen, hydrogen and carbon). In many cases, eliminating operations of gaseous elements have not been always made commercially, because these impurity elements could not be eliminated by usual treatments applied to the purification of ·common metals. As an alternative method, authors have proposed the· application of the SSE process to the elimination of gaseous impurities from rare earth metals. Investigations have been carried out on the yttrium-oxygen and neodymium-oxygen systems and the results were already reported[3,4]."

Jan 1, 2000

By Yuanbo Zhang, Huanpeng Mi, Guanghui Li, Binjun Liang, Zhiwei Peng, Tao Jiang

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination. In this study, sodium salts were employed to enhance the separation of iron and boron by reductive roasting-magnetic separation. It was found that the separation of iron and boron as well as the iron grade and recovery were significantly improved b y the addition of Na2SO4 or Na2CO3. Under the reduction temperature of 1050 °C, reduction time of 60 min and magnetic intensity of 0.1T. Compared with the inexistence of sodium salts, the iron grade and recovery of the magnetic concentrate increased from 83.3% and 88.6% to 93.2% and 95.1%, respectively, by adding 6% Na2CO3. The XRD and microstructure analyses indicated that the iron oxides were transformed into metallic iron and the average metallic iron grains were grown to over 40μm which was beneficial for separation of metallic iron from gangue.

Jan 1, 2016

By Y. A. Chang, L. M. Pike, C. R. Kao

"Knowledge of the site preference of ternary solute additions is essential to developing an understanding of how these solutes affect the properties of B2 intermetallic compounds. A quasichemical model will be presented which is able to predict the site preferences of dilute solute additions to tliple defect B2 compounds. The only parameters required are enthalpies of formation at the stoichiometric composition. General equations are developed which can be used to determine site occupations and defect concentrations for dilute as well as non-dilute solute additions. These equations use atom pair bond enthalpies as the parameters. It is found that the site preferences of dilute additions are not always in agreement with predictions based on the solubility lobes in ternary Gibbs isothelms. Predictions for dilute additions to NiAl and FeAl are compared to expel1mental results found in the literature. Satisfactory correlation is found between the model and the experimental results. In addition, the predictions from the model on vacancy concentrations in Fe doped NiAl are compared to recent experimental results by the authors.1.0 IntroductionIntennetallic compounds with the B2 crystal structure such as NiAl and FeAl have been investigated recently for possible use as structural materials in high temperature, oxidizing, and/or corrosive environments. The major limiting property of these materials has been a lack of sufficient room temperature ductility. Attempts to improve the ductility have often been made through ternary or higher order alloying. For B2 compounds, substitutional alloying additions can occupy either of the two sublattices and this site occupancy can be crucial in determining how the alloying addition affects the properties of the alloy. In this manuscript we will discuss the use of thelmodynamic modeling to predict the site occupancies of ternary alloying additions in B2 compounds with the triple defect structure."

Jan 1, 1996

By Hui-Gai Li

The fine Ti oxide inclusions precipitated during solidification are favorable for intragranular ferrite nucleation. The oxygen content before solidification affects the composition and size of inclusions. The composition of precipitated inclusions in Mn-Ti alloyed steel was studied by means of thermodynamic calculation and experiment in this paper. The micro-segregation of Mn, Ti and O during solidification was considered in calculation and unidirectional solidification apparatus was employed in experiment to ensure that alloy elements diffused along solidification direction. The results showed that: inclusions are mainly Ti oxide when oxygen content is 10ppm; they are Ti oxide and Mn-Ti oxide when it is 20ppm; Mn-Ti oxide dominates when it is 30ppm. With the increase of oxygen content, the size of inclusions increases. The maximum oxides size is about 3µm from statistical results of experiment.

Jan 1, 2008

By Byung-Su Kim

The recovery of elemental sulfur from sulfur dioxide has important implications for coal- burning power plants and nonferrous metal smelters. The thermodynamic analyses showed calcium sulfide to be suitable for recovering elemental sulfur from sulfur dioxide. At the temperatures of 1023 to 1153 K under the sulfur dioxide partial pressures of 5.0 - 60.1 kPa, elemental sulfur from sulfur dioxide was recovered by its reaction with calcium sulfide. The kinetics of this reaction were measured at the same conditions using a thermogravimetric analysis technique. This reaction scheme would be attractive if the coproduct calcium sulfate can be reduced to regenerate calcium sulfide. This is the topic of another paper. At 1073 K under the sulfur dioxide partial pressure of 25.8 kPa, 48 % of the original calcium sulfide was converted to calcium sulfate in an hour. Under the same conditions, 55 % of the regenerated calcium sulfide were converted to calcium sulfate in an hour even after third regeneration.

Jan 1, 1999

By M. J. Collins

A hydrometallurgical process has been tested at the Sherritt Research Centre for separation of zinc, lead, copper and precious metal values from the zinc oxide fume leach residue stockpiled at the HBM&S operations in Flin Flon, Manitoba. Zinc is found primarily as zinc femte and sphalerite in the residue, lead as lead sulphate and jarosite, and copper as sulphide and jarositic compounds. Gypsum and siliceous gangue are significant diluents. The separation process includes hot acid, atmospheric and reducing (sulphur dioxide) leaching; zinc, copper and lead flotation; and atmospheric iron removal steps. Zinc is recovered to a high strength zinc sulphate solution and to a zinc sulphide concentrate suitable for feed to a roaster or to a zinc pressure leach plant; lead to a high grade lead sulphate concentrate suitable for feed to a lead smelter, and copper to a high grade copper sulphide concentrate suitable for feed to a copper smelter. Precious metals are divided between the zinc, lead and copper concentrates.

Jan 1, 1993

By Xin Zhang, Xu Zhang, Hao Bai, Ning Li

Organic Rankine Cycle (ORC) is an effective technology for low-grade waste heat power generation. In this paper, the thermal-dynamic performance of ORC system, in which low-temperature waste heat (from 40-140oC) is used as heat source, was evaluated with software RefProp8.0. The result indicates that in the range of low temperature, the working fluids like R601, R601a, R600a, R141b, R245fa and R245ca have better thermal performance. Furthermore, pilot-scale experiment using R245fa as working fluid was conducted, which validated the operation of the system for low-grade waste heat recovery. Finally, the economic feasibility of ORC has been analyzed for an ORC system using the waste heat from quenching water of blast furnace slag (80oC). According to the analysis, the project is reasonable in economy because the recovery period of investment is less than 4.2 years and environment-friendly since the CO2 emissions can be reduced by almost 43650.68t annually.

Jan 1, 2016

By A. Martins, L. Goulart, E. Araujo, R. Batista, A. Costa e Silva

Steel cleanness is of great importance to the performance of almost all steel products. From very clean steel for bearings to long products used in civil construction, processing variables – in special those in steelmaking operations- must be properly balanced to achieve adequate cleanness for the desired performance. With the present complexity of steels as alloy systems, it is not efficient nor appropriate to develop these processes on empirical basis alone. Computational thermodynamics can greatly improve process development to achieve the desired cleanness level at reasonable costs. In this work, examples of these calculations and their applications to real steel processing are presented and discussed. The advantages, limitations and areas in which improvement in these calculations is desired are highlighted and discussed.

Jan 1, 2015

By Jian Li, P. Liu, R. Zhang and J. Lo

In the past decades, focused ion beam (FIB) has evolved into a powerful microscope that provides capabilities that no other microscopes can offer. The combination of high-resolution imaging and stress-free ion beam cross sectioning provides valuable microstructure information both at the specimen surface and beneath. FIB techniques are also the preferred method to prepare site-specific transmission electron microscope (TEM) specimens. CanmetMATERIALS owns a world-class microscopy facility, where advanced microscopy work provides strong supports to research programs that cover a wide range of subject areas. This paper is aimed to provide a few practical examples of FIB applications in microstructure characterizations that include cross-sectioning and imaging, serial sectioning, and advanced TEM specimen preparation in materials research at CanmetMATERIALS.

Jan 1, 2015

By Tracy Lucas, Ian Hamill

"Issues of importance in the area of continuous casting centre around product quality. This can be affected by particle inclusions transported into the mould from upstream processes and by draw-down of particles from the meniscus. Turbulence of the meniscus can increase the latter and is also detrimental to product surface quality.Suitably validated Computational Fluid Dynamics (CFD) modelling can provide the operator with an efficient tool with which to investigate the effects of changes to the design and operation of the caster and associated plant.In this paper, examples are presented of the use of the CFD software, CFX, to simulate:•,free-surface shape and turbulence in the mould using deforming meshes•,solidification in the mould using a fixed-grid, source-based method•,argon gas injection through a submerged entry nozzle using a full multiphase model•,inclusion motion and removal in tundishes using an algebraic slip model.The CFD simulations of the free surface shape are complemented by detailed Particle Image Velocimetry measurements performed on a full-size water model of a thin-slab mould and upper strand. Close agreement is demonstrated between the predictions and experiments."

Jan 1, 1999

By Sungdon Kim, Chuljoo Kim, Joonsoo Kim, Hosung Yoon

"This study was performed to establish the optimum leaching condition through the experiments for the oxidized roasting followed by leaching of fluorocarbonate rare earth mineral (bastnasite) using sulfuric acid, and to establish the optimum condition for the recovery of cerium by ion- sieve method from the leached solution of bastnasite. The optimum conditions for the sulfuric acid leaching by the oxidizing roasting of bastnasite concentrates are that the roasting temperature is 550 -600 °C, the roasting time is 2 hrs, the concentration of sulfuric acid is 6N, the leaching temperature is S0°C and the leaching time is 3 hrs. At this time, the leaching yield of total rare earth oxides in the leaching of bastnasite concentrates is about 91%. When cerium is recovered by ion-sieve method from the solution obtained by the sulfuric acid leaching of the roasted bastnasite, the optimum conditions are that the TREO(total rare earth oxide) of leached solution is below 70 g/l, the flow rate of leached solution is 9.6 ml/min and the ratio of height to diameter of resin packed in column is above 9. In these conditions, the recovery of cerium of yield 85% and purity 96% is possible.IntroductionThe rare earths are generally called to Lanthanides, which are totally 17 elements including Scandium of atomic number 21 and Yttrium of atomic number 39 in addition to 1 S elements from Lanthanum of atomic number 57 to Lutetium of atomic number 71. Since the separation to each element is very difficult because of their similar chemical properties, the rare earths were used as the mixed rare earths and the mischmetal without separating to each element. However, the high purity rare earths are recently produced commercially to each element so that they are used as the materials for high tech. industry such as electric and electronic materials, catalysts, optical materials, special alloy and 8Uperconductive materials, and their consumption is rapidly increasing. Therefore, the purpose of this study is firstly to prepare leached solution by using the series of process of the oxidation-roasting and leaching by sulfuric acid. Next, second purpose is the separation and recovery of cerium by ion-sieve method."

Jan 1, 1998

By Zeng Zheng, Liu Chen, Yu Xing-Fu, Tian Su-Gui, Zhang Chao

"Single crystal nickel-base superalloy is prepared by using the various withdrawing rates. By measuring creep properties and microstructure observation, the influence of the element segregation on creep properties of the superalloys is investigated. Results show that the dendrite spacing and the segregation extent of the elements decrease with the enhancing withdrawing rate. The superalloy with smaller dendrite spacing has lower segregation of the elements and better creep resistance. The dislocations climbing over the rafted y’ phase is thought to be the deformation mechanism of the alloy during steady state creep. In the later stage of creep, the fact that some dislocations shear into the rafted y’ phase may twist the rafted y’ phase. As the creep goes on, the initiation and propagation of the cracks occur up to occurring creep fracture, which is thought to be the fracture mechanism of the superalloy during creep.1. IntroductionSingle crystal nickel-based superalloys consist of high volume fraction of ?? strengthening phase and ? matrix, and possess the excellent high-temperature mechanical and creep properties, therefore, they have become the main material to make the blades of the advanced aeroengines[1-3]. Some literatures report that the temperature-bearing and creep-resistance properties of the single crystal nickel-based superalloys can be remarkably improved as the increases content of the refractory elements, such as W and Re[4-6]."

Jan 1, 2012

By W. K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating improved technology for mineral flotation. A variable often neglected in flotation control is redox potential. The use of redox control is illustrated by the separation of molybdenite from chalcopyrite. Laboratory testing showed that redox potential had a greater effect on product quality than collector addition. A significant need in froth flotation is greater reliability of the sensors used in measuring and controlling redox potential in mineral slurries. The USBM has developed an automated method for removing scale and reconditioning gold redox-sensing electrodes. Fouled electrodes are anodically polarized to 1.2 V versus the AglAgCI reference potential to remove scale. The electrodes then are conditioned by a brief potentiodynamic treatment to re-establish electrochemical equilibrium. In laboratory tests, this technique removed calcarious deposits from gold electrodes and reconditioned them for useful service in approximately 10 min. In plant practice, this technique would obviate the need for plant operators to manually polish electrodes, and also should result in greater reliability in redox measurements. Inexpensive, automated equipment to condition electrodes in a plant setting is described.

Jan 1, 1995

By Jie Li, Shu Yang, Zhongliang Tian, Xun Hu, Yanqing Lai

The purity of the electrolyte has an important influence on the content of the impurities in electrodeposited silicon. In this paper, effects of electrolysis temperature, current density and the time on the concentrations of two important impurities: phosphorus and iron in the electrolyte were investigated during the purification of Na3AlF6-10%K2SiF6-AlF3 melt. It was observed that the concentrations of P and Fe in the electrolyte decreased with the electrolysis temperature, current density and the electrolysis time increasing. X-ray fluorescence (XRF) of the electrolyte shows that the concentrations of P and Fe decrease from 4.2ppmw to 1.3ppmw and 204.0ppmw to 42.6ppmw, respectively. The removal rates of P and Fe are 69.08% and 79.12% when the electrolysis was performed for the duration of 3 hours and at a current density of 20mA·cm-2 while the operating temperature was 1225K.

Jan 1, 2015

By Guolin Zheng, Jian Pan, Deqing Zhu, Xianlin Zhou

"In ferronickel production, nickel oxide and part of the iron oxide are reduced to metal by agglomeration and smelting in blast furnace. Due to the physical and chemical properties of the laterite ores, a large fraction of fines is generated during the pre-treatment stages and the strength of agglomeration is weakened, which results in low productivity and bad quality. In this paper, the process of pelletization of nickel laterite was developed, and some parameters to strengthen the pelletization of nickel laterite have been optimized. The results show that the compressive strength of fired nickel laterite pellet can reach over 2000 Newton per pellet while firing at the temperature of 1220 °C~1250 °C in 12 min. The product pellet can be used as high-quality burden for blast furnace to manufacture ferronickel.IntroductionIn recent years, the global stainless steel market was developed exuberantly, which greatly promoted the needs of the basic raw material of stainless steel smelting - metal nickel. Currently nickel sulfide ores are only 40% of global nickel reserves, but offer 60% of all the nickel production. However, with the deficit of resources, the nickel sulfide ore (high grade ore) is depleting, so there is an increasing focus on the utilization of low-grade nickel laterite. Recent research has focused on the wet treatment process to utilize nickel laterite, and less on the use of other technologies [1-8]. The economical and efficient technology relies on the reduction of nickel oxide and part of the iron oxide metal by agglomeration and smelting in blast furnace in China. Some domestic steel companies have adopted this process [9, 10]. Unfortunately a large fraction of fines is generated during the pre-treatment stages and the strength of agglomeration is weakened, which results in low productivity and bad quality of fired pellets. In this study, the process of pelletization of nickel laterite was developed firstly, and some parameters to strengthen the pelletization of nickel laterite have been optimized, and the product pellet can be used to produce stainless steel and ferronickel alloy by blast furnace."

Jan 1, 2011