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By Anxiang Wang, Kunhua Wu, Yifu Li, Junjie Xu, Yongnian Dai, Bin Yang, Lingxin Kong

In this study, the saturated vapor pressures of tin (Sn) and antimony (Sb), the separation coefficient and the vapor-liquid phase equilibrium of Sn-Sb alloy were theoretically analyzed, which demonstrate that it is possible to separate Sn and Sb by vacuum distillation. The process parameters of vacuum distillation, including the distillation temperature, distillation time and alloy mass (thickness of raw materials) on the direct yield of Sn and the content of Sn in liquid phase were investigated by using single factor experiments. The preliminary results show that the direct yield and the content of Sn are 98.77 wt.% and 96.01% with the optimized distillation conditions of a distillation temperature of 1473 K, a distillation t ime for 45 min and a Sn-Sb alloy mass of 125 g ( thickness o f 8 mm). The distillation parameters in the study provide effective and convenient conditions on separation of Sn-Sb alloy.

Jan 1, 2016

By Zhigang Liang

Investigation into the mixing of 150t ladle furnace by two-nozzle jetting was performed by a water model simulation of 1:4. The effects of nozzle arrangements including separation angle, radial position and asymmetry as well as tracer adding position on the mixing time were studied. The most favorable mixing is achieved when the two nozzles are symmetrically arranged at half radii in the ladle, with 45o separation angle. The empirical relationship between the mixing time and stirring power intensity has been established for two-nozzle jetting based on the present experimental results. In addition, the swelling above bath surface is also investigated with two-nozzle jetting.

Jan 1, 2009

By R. Lanza, M. Hytros, N. Saka, I. Jureidini, J. H. Chun, D. Kim

"A novel method for delineating the solidification front in metal casting has been developed using the attenuation phenomenon of electromagnetic radiation (y-rays or x-rays) and computed tomography (CT). The densities of the liquid and solid phases that exist during metal casting may differ anywhere from 4 to 12 % depending on the metal. As in the medical imaging field, CT provides an excellent means of mapping this density variation in a solidifying casting into two-or three-dimensional images.In an effort to develop an industrial-scale sensor, laboratory-scale experiments have been conducted using a cobalt-60 (Co60) radioisotope and a sodium-iodide (Nal) scintillation detector. The CT image reconstruction was performed on a crucible containing pure tin in a two-phase state. Although the spatial resolution and data acquisition speed were not optimum, the CT images clearly differentiate the liquid and solid phases of the tin in the crucible. To maximize resolution and minimize data acquisition time, a linear accelerator (linac)-based CT sensor is being developed and tested for application in the continuous casting of steel and aluminum alloys.IntroductionIn all casting processes, the quality of a finished product and its production rate depend upon the shape and movement of the solidification front. From a quality perspective, it is well documented that solidification kinetics (heat and mass transfer, fluid flow, microstructure evolution) greatly influence the final properties of castings [l,2,3]. Product shortcomings, such as surface defects, cracks, macro-and microsegregation, and inclusions are directly controlled by the solidification process. By understanding the role the solidification front plays in the casting process, product quality may be dramatically increased through the reduction of defects."

Jan 1, 1997

By Zhihe Dou, Jiang Liu, Ting-an ZHANG, Yukun Huang

The paper aimed to propose that mixed rare earth concentrate was decomposed by pressurized calcification where mechanical milling was applied simultaneously (also known as mechanochemical calcification). The bastnaesite and monazite were both decomposed by OH−, where released rare earth formed RE (OH)3, released fluorine and phosphorus formed CaF2 and Ca2P2O7. Then, the calcified slag was leached by diluted hydrochloric acid to extract rare earth and both recover fluorine and phosphorus. The phase transformation regularity, the behavioral trends of rare earth, fluorine and phosphorus were investigated. Results showed under the optimal conditions of ball to material weight 80:1, the calcification temperature 250 °C, the liquid-solid ratio 5:1, the leaching yield of rare earth reached to 92.16%, Ce was 86.47%, La was 97.58%, Nd was 99.99% and the mass fraction of F, P entering into calcified liquor were 8.27, 0.21% respectively. The micromorphology of the mineral has a transition from dense to fluffy, and then became dense again.

Mar 1, 2018

By Jong-Ren Tarng, Gin-Hwa Chen, Wen-ku Chang, Ke-Ming Lin, Yuan-Haun Lee

"The majority of early studies used X-ray diffraction, but this requires a model to interpret the diffraction processes. A turbostratic model has been applied by Warren, Franklin and Bacon to a wide range of materials including both soft and hard carbons. Maire and Mering applied the same methods to the interpretation of the (001) lines of a series of graphitic carbons. In our case, graphitic carbons undergone high temperature and high pressure graphitization processes have been evaluated by the same methods. It were found that most technological XRD data were obtained by a Rietveld method with the least-squares refinements could be in the simplest way since the full correction technique is very laborious. The behavior of carbon materials as it proceeds through the graphitization process is characterized by changes in the measured interlayer spacings (d) a~ a function of temperature. A series of graphitic carbons including the transformation of diamond to graphite through the process under high temperature and high pressure have been evaluated. A simple calibration equation has been established. IntroductionRecently, in battery industry, carbon materials are used as cathode in lithium ion batteries. However, graphitization of those carbon materials is concerned as if lithium ion intercalated into those carbon cathode. Both high-graphitization and low-graphitization carbon materials are suitable for this kind of application.As for graphitization, the starling materials from which carbons may be prepared vary extensively from pure chemical compounds, to mixtures containing II wide range of molecular weights, such as pitches. So its graphitizing, perhaps the most notable feature of the process, is the very wide range of temperature over which the perfection increase, unlike the more common transformations of solid state materials which occur in a narrow temperature range. The variables involved in the conversion of the initial hydrocarbon to a carbon residue, which may vary widely in final perfection, are time, temperature, stress and impurity content"

Jan 1, 1996

The merging of flash smelting with spray converting in one single furnace is proposed as a continuous copper making process. The proposed process is expected to produce blister copper, clean slag and gas with high sulfur dioxide concentration. Some high grade matte is an intermediate product recycled within the proposed furnace, spray-atomized and converted. The thermodynamic equilibria of the simultaneous oxidations which take place during copper smelting and converting are discussed in order to establish the gradient of oxygen potential along the furnace required for smooth operation. The proposed process is a dynamic system designed to reach equilibrium only close to the slag skimming end of the furnace. The process feasibility is based on the predesigned significant difference between the rates of converting reactions in a finely dispersed system and the rates of deconverting reactions between immiscible liquid phases of restricted interface area. The converting of small stationary droplets of matte, in a silica saturated system, was studied in the laboratory for extremely short oxidation times (10 to 120 seconds). These experiments led to some interesting observations on reaction mechanisms and kinetic trends. The droplet size and the matte grade affected very strongly the oxidation rate and the proportion of the different products obtained.

Jan 1, 1976

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By Ian Masters

Rotary furnaces are widely used throughout the metals industry. These furnaces vary in size and geometry, but are fundamentally the same from a thermodynamic viewpoint. A generic method is proposed that can be used to model all furnaces of this type, provided that the correct material and process parameters are known. Various approaches have been attempted in the past based on a continuum (FEA or CFD) approach. However, the complex fluidlsolid interactions present in a rotary vessel are not easily solved using these methods, which work best where the material boundaries are well defined. In this paper a lumped parameter model is proposed. Variations within a section of the model are ignored, but to ensure thermodynamic correctness, the heat transfer between sections is carefully considered. For example, it is reasonable to assume that the whole of the melt pool is at the same temperature, due to rotary mixing. This may then be modeled with a single set of parameters, and the detail is contained in obtaining the correct heat transfer mechanisms from the rest of the furnace.

Jan 1, 2002

By B. M. Satish

The aim of the present work is to study the effect of annealing on the vibration damping capacity of high-chromium (16%) ferromagnetic steel. The alloys were prepared from raw materials of 99.9% purity melted in a high frequency induction furnace under high vacuum. The samples were heat-treated in vacuum at various temperatures (800 to 1200°C) for 1 hour followed by slow cooling (120°C/h). The inverted torsional pendulum method was used to evaluate the vibration damping capacity. The results indicated that the vibration damping capacity of the alloys is influenced by annealing and there exists a critical annealing temperature after 1000°C. The damping capacity increases quickly below the critical temperature since the magnetic domains move more easily.

Jan 1, 2009

By Wang Shulan

The synthesis process of BaTiO3 from TiO2 and BaCO3 in the molten NaOH-KOH at 350oC was studied by the A.C impedance technique. The A.C. impedance of molten NaOH-KOH (xNaOH = 0.36) and the variation of the conductivity of the salt with time during the synthesized process were measured. The synthesized reaction of the BaTiO3 and the decomposition reaction of BaCO3 are fast and were finished in 10min. The interaction between TiO2, BaO and BaTiO3 and the molten salt was confirmed by the variation of the conductivity.

Jan 1, 2005

By John J. Mazza

Treatability studies were performed to determine the effectiveness of two commercially available treatment methods (solvent extraction and thermal desorption) for the removal of PCBs and PAHs from contaminated dredged riverbed sediments. The solvent extraction method evaluated was the B.E.S.T. process which extracts the contaminants with triethylamine. The thermal desorption method utilized was the ATP process which desorbs the contaminants at elevated temperature in an anaerobic atmosphere. A description of both methods and. an evaluation of the treatability study results is provided. Each treatment method was used to treat two separate samples (high and low concentration) from the site. Overall, both methods proved to be very effective with solvent extraction achieving 98% removal of both PCBs and PAHs and thermal desorption achieving better than 99% removal of both the PCBs and PAHs from the high concentration sample. Both solvent extraction and thermal desorption achieved greater than 99% removals of PCBs and PAHs from the low concentration sample. Vendor cost estimates for full scale treatment were roughly equivalent. The primary differences between the two methods lies in the realm of permitting, operational requirements, and emission concerns.

Jan 1, 1994

By Nieves Iglesias

The removal of the refractoriness of a gold bearing pyrite- arsenopyrite ore is studied. Flotation concentrates were prepared and leached with a dilute acidic ferric sulfate solution. The elemental sulfur film which forms on arsenopyrite in the oxidation process is not responsible for the low rate of the arsenic dissolution observed. A positive effect on the leaching rate is observed when Ag' is added. This pretreatment eliminates the refractory nature of concentrates.

Jan 1, 1993

By M. Krishna, Jayagopal Uchi1, Shanta Sastry, B. M. Satish

"A well-considered composite of ZA-27 reinforced with weight percentage 0, 2, 4, and 6% of alwninite particulate has been made by compocasting technique. The elastic properties of ZA- 27 /alwniniute particulate composite were determined by using U1M. The results showed that the modulus of elasticity and UTS of the composite gradually increases with increase in the wt.% of reinforcement. However, the overall ductility decreased monotonically with an increase in reinforcement. The results of these tests· as well as the predictions of several model~ for composite strengthening available in the literature were compared with experimental results. The data observed from Young's modulus by measurements studies were compared with theoretical results predicted by Eshelby model.IntroductionMetal matrix composites (MMCs) have received increasing attention in _the recent decades as engineering materials. The introduction of a ceramic reinforcement into a metal matrix produces a composite material resulting in an attractive combination of physical and mechanical properties that cannot be obtained with monolithic alloys. Particulate reinf9rced MMCs among the discontinuously reinforced MMCs have attracted quite a lot of attention both in the industrial sectors and the academic communities. There is an increasing need for knowledge about the processing techniques and mechanical behavior of particulate MMCs in view of their production getting enhanced and their commercial applications becoming wider [I]. Interest in particulate reinforced MMCs is mainly due to easy availability of particles and economical processing techniqu"

Jan 1, 2000

By Andrea Bernardes

Printed circuit boards (PCBs) of varying compositions have been converted by incineration and following melting into an environmental agreeable slag and a copper-nickel-tin alloy, containing the precious metals. The environmental compatibility of the slag was determined according to the German standard DIN 38414 - Part 4; pollutants' concentration in the lixiviates is smaller than the thresholds of drinking water (CE-Standards). Each experiment the charge were 500g scrap from PCBs and ca. 100g slag forming material. The products were a kind of mullite slag, poor on iron, which was recirculated, and an alloy containing up to 0.3% Gold. With a burner to the retort coal gas, the waste gas was burned without soot, and the produced mixed zinc-lead oxide containing silver was collected in the flue dust.

Jan 1, 1997

By Barry Welch, Kai Grjotheim

"The capital intensive nature of the present process for aluminium smelting, the low productivity per unit reactor, and pressure to reduce the electdcal energy demand have motivated the search for an alternative process. Optional routes include carbo-thennal reduction of alumina (using an alloy phase immediate), chlorination followed by electrolysis of aluminium chloride, and electrolytic decomposition of alumina using inert electrodes. Materials performance and reactor design constraints have been a major limitation for alternatives. However parallel research has led to considerable advances in the process efficiencies and scale of both the Bayer process and the Hall-Heroult cells.Future development of alternatives is dependent on breakthroughs in Materials Science such as the development of stable conducting anodes and stable wettable cathode materials. However if successful it is probable that some spin-offs will be retrofitted to existing cells. Therefore the basic Hall-Heroult technology will continue as the dominant process for at least the next half century.IntroductionThe present Bayer/Hall-Heroult process for production of aluminium is just over 100 years old. Frequently, during the century of its technological development questions have been raised as to whether it is the ideal route for metal production. The questioning was particularly intense in the period between the mid-1950s and the mid-1060s when the limitations of the Hall-Heroult electrolytic stage were evident. Then the cells were only 30 to 35 % efficient with respect to the utilisation of the hydro-electricity (requiring 16 18 kWh/kg, thus making it strongly dependent on cheap electrical energy), while the size of cells being installed were 80 to 130 kA. Hence the process was capital intensive, the productivity per reactor volume low, and the process was labour intensive (requiring about 15 man hours per tonne of aluminium). In addition, the use of pitches for Soderberg anodes and the fluoride electrolyte were creating problems through emission. At that time material science had paid little attention to the manufacture and use of carbonaceous materials or the development of alternatives that were corrosion resistant to cryolite or liquid aluminium. Hence cell lives were short - typically 600 to 1000 days - thus adding to operating costs. Thus the grass over the fence, as foreseen in 1960s vintage crystal balls appeared much greener for alternative processes."

Jan 1, 1988

By Omid Marzoughi

In this research, both the kinetics and the mechanisms of the roasting of a sphalerite concentrate from the Bafgh mining complex in Iran were investigated. The oxidation process was performed in a muffle furnace in air and the effects of time and temperature on the degree of oxidation of the zinc sulfide sample were quantitatively studied. The experimental data were fitted to the shrinking core model. In the temperature range of 650–800 °C, the rate-controlling step was the chemical reaction between the zinc sulfide and oxygen with an activation energy of 103 kJ mol−1. On the other hand, in the temperature range of 850–950 °C, the rate-controlling step was oxygen diffusion with an activation energy of 50 kJ mol−1. Also, the roasting process was studied using thermogravimetric (TGA) and derivative thermogravimetric (DTGA) techniques.

By Payman Roonasi

Having knowledge of mechanism of magnetite formation is essential in a number of industrial processes including magnetite synthesis and corrosion of iron. In this study, magnetite nanoparticle was synthesized via two different ways; coprecipitation of iron (II) and (III) and oxidation of ferrous hydroxide. The samples were characterized using X-ray diffraction (XRD), Mid-Far IR spectroscopy, scanning electron microscopy (SEM), chemical analysis for determination of Fe II/Fe III ratio and ICP-MS for iron isotopic ratio (56Fe/54Fe) measurement. Since fractionation of iron isotopes depends on reaction rate and bonding strength, interpretation of the isotopic data with respect to the possible mechanisms is discussed. No fractionation of iron isotopes was observed for the magnetite synthesized by coprecipitation, whilst magnetite formed from ferrous hydroxide showed higher abundance of 54Fe compared to 56Fe in the beginning of reaction, implying the significance of the following reaction:

Jan 1, 2009

By Thomas Niehoff

Many industrial processes require energy. Energy is required for melting or heating purposes. The heat can be generated by electrical heating or combustion/oxidation of hydrocarbons. Oxygen supports the combustion process. Oxygen is naturally contained in air with about 21 vol.-percent. The use of technical oxygen will allow an increase to the natural oxygen concentration of combustion air. Altering the combustion process by increasing the oxygen content has various effects. These effects are described and analyzed with regard to heat transfer, emissions and energy consumption. Industrial processes requiring oxyfuel are described and discussed regarding energy aspects.

Jan 1, 2008

By Gaballah Djona M.

Spent hydrorefining catalysts contain about 5 % of CoO and/or NiO, 12 % of MoO3 and up to 10 % of V205. They are generally supported by alumina and contain up to 25 percent of C, S and hydrocarbons. Such materials are potentially hazardous to the soil and to water resources. Selective chlorination of raw unroasted samples with Cl2 + air gas mixture had been investigated. At temperatures lower than 600 °C, it was possible to recover more than 90 % of nickel and cobalt chlorides, about 99 % of the molybdenum and up to 75 % of vanadium chlorinated compounds. CoCl2 and Ni/Cl2 were extracted from the chlorination residues by their dissolution with acidified water. Molybdenum and vanadium chlorinated compounds were recovered by selective condensation from the vapor phase. The chlorination of Al2O3 could be limited to less than 6 %. The scale up of this treatment was successful and a flow-sheet is proposed.

Jan 1, 1995

By Frank A. Vonesh

In order to reduce the amount of visible, airborne emissions in the Metals Industry, a new Industrial Gas Technology was developed by Air Liquide. This patented technique is called ALECT?, Air Liquide Emission Control Technology. Demonstrations have been conducted for many cutting and lancing operations as well as for hot metal transfer from vessel to vessel. Fume reductions of 90% and greater have been achieved in actual practice. Air Liquide continues to improve the process and the associated control equipment.

Jan 1, 1994