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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 Jiang Fan, Liu Shi, Wang Haigang

Winter-time natural convection in gravel embankments has been suggested as a technique to provide passive cooling and thereby avoid thaw-settlement of roadways located in permafrost areas. Numerical simulation by finite volume method on the proposed model is perf9rmed using the software FLUENT. A gravels model, in which the embankment is composed of stones and air, has been adopted to investigate the temperature and velocity fields in embankment. Simulation results show that in summer, a weak clockwise circulation of the pore air extending throughout most of the embankment. The pore-air motion is very weak which results in relatively straight horizontal isotherm lines. And heat transfer is mainly maintained through conduction. But in winter, pore-air velocities are higher and multiple vortexes are formed in the embankment. Natural convection then becomes the dominant influence on the isotherm shapes within the embankment. As a result of low ambient temperatures exerted on the embankment surface during winter months, an unstable air density gradient develops within the embankment. This convection increases the heat flux out of the embankment. Therefore, the winter-time convection can further reduce the temperature of the foundation soil beneath the open-graded embankment. In addition, the effects of the size of the stones within the embankment have been analyzed and compared in the gravel model. It shows that in winter, 200mm stones lead to stronger vortexes in the embankment compared with those of 60mm stones. Consequently, the zone oflow-temperature beneath the embankment is extended.

Jan 1, 2004

By S. G. Kumar

Experimental studies on high carbon steelmaking through LD Converter - Vacuum Arc Degassing - Bottom Pouring route to produce low oxygen steels were carried out. The results indicated that it is possible to produce steel with a total oxygen content of less than 15 ppm. Thermodynamic and mass balance calculations are made on low-carbon steels that are treated by a complex deoxidation practice based on primary deoxidation of aluminum, manganese and silicon additions; followed by secondary deoxidation of vacuum degassing with simultaneous additions of aluminum. The results showed that primary deoxidation is mainly due to aluminum and the effect of carbon under reduced pressures on deoxidation of molten steel that is already killed by aluminum is negligible. The effect of process parameters on total oxygen content of steel, like carbon content, slag composition and inert gas purging, are discussed.

Jan 1, 1994

By B. J. Jody

At Argonne National Laboratory, we have been developing a potentially economical process to recycle automobile shredder residue (ASR). We identified three potentially marketable materials that can be recovered from ASR and developed technologies to recover and upgrade these materials. We built and tested a field-demonstration plant for recycling polyurethane foam and produced about 2,000 lb (907 kg) of recycled foam. Several 300-lb (I36-kg) samples were sent for evaluation and were found to be of marketable quality. We are also preparing for a large-scale test in which about 200 tons (181 tonnes) of ASR-derived fines «0.25 in. [<0.62 cm]) will be used as a raw material in cement making. A major cement company has evaluated small samples of fines prepared in the laboratory and found that they meet its requirements as a substitute for iron ore or mill scale. We also produced about 50 lb (23 kg) of recycled acrylonitrile butadiene styrene (ABS) from obsolete automobiles and found that it has properties that could be readily upgraded to meet the specifications of the automotive industry. In this paper, we briefly discuss the process as a whole and summarize the results obtained from the field work on foam and fines recycling.

Jan 1, 1996

By Yufeng Guo, Tao Jiang, Jianjun Fan, Haizheng Hao

"Function of High Pressure Roll Grinding (HPRG) in production of oxidized pellets from magnetite concentrate as raw material was systematically studied. It was found that bentonite dosage decreased from 1.3% to 0.8% if specific surface area of magnetite concentrate pretreated by HPRG was up to 2553.41cm2.g-1. The green ball quality improved obviously due to the increase of specific surface area and fine particles content, and the improvements of size distribution and the ballability of pretreated materials. However, the decrease of pellet porosity accelerated the primary solid phase reaction and oxidation reaction, which made the pellets surface form compacted layer that handicapped the diffusion and migration of oxygen, promoting the formation of double layer structure of finished pellet. Consequently, the compression strength of preheated and roasted pellets was not markedly improved by HPRG.IntroductionWith the increase of proportion of pellets in the BF recently, the technical-economic index of BF has obviously been improved. Consequently, the production and the quality of BF pellet are given more attention [1]. However, with the decrease of the quality of iron ore concentrate, the problems such as poor ballability, high bentonite dosage, high preheating and roasting temperature are becoming the great challenges to not only the quality of finished pellets, but also the energy consumption [2, 3]. In order to overcome these problems, mechanical pretreating technologies such as the High Pressure Roll Grinding (HPRG) and Damp-grinding are widely applied. HPRG has a number of advantages such as low energy consumption, high productivity and easy-maintaining. It is more economic and environmentally friendly than the Damp-grinding technology [4, 5]. A great number of experiments have revealed that HPRG can improve the quality of hematite pellets. Although there are some studies of function of HPRG in the magnetite oxidized pellet production, they are not comprehensive and systematic, especially to the preheating and roasting system [1, 2, 6, 7]. Accordingly, the influence of HPRG on the pelletizing system and the preheating and roasting system are systematically studied in production of magnetite oxidized pellets in this article."

Jan 1, 2011

By Federico Chavez

The process for recovering lead from battery residues used in several Mexican Plants include lead blast furnace and rotary furnaces. The formers are basically fed with recycled batteries together with the necessary additives to produce metallic lead. One of the by-products generated in the blast furnace is a dust mainly formed by lead sulfide. The rotary furnace is used to recover lead .from lead batteries, dross from the refining-alloying process and the leady fines produced in the blast furnace. This paper describes thennodynamic analysis made to the rotary furnace process to understand the effect that each component of the system has upon the lead recovery. In order to enhance the process, the influence of iron chips composition and excess coke on slag viscosity is discussed. A computer optimization program . has been developed to design the furnace charge based on material and energy balances, .together with the thennodynamic equilibrium calculation.

Jan 1, 1995

By Baokuan Li, Qiang Wang, Zhu He

"A mathematical model has been developed to investigate the magnetohydrodynamic (MHD), thermal, and solidified behavior in electroslag remelting process. Based on the finite volume method, a multiphase coupling MHD approach is employed to investigate the droplet formation as well as movement in molten slag under the action of an alternating current. The VOF formulation is adopted for interface tracking. The electrical potential method is adopted for the electric current and magnetic field. The Electromagnetic force and Joule heating are recalculated at each time step and then is implemented in the momentum and energy equations as a source term, respectively. Moreover, solidification of the metal is described by an enthalpy-based formulation, while the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. The model is used to investigate the effect of electrode tip shape on MHD, thermal, and solidified behavior and provide valuable information.IntroductionElectroslag remelting (ESR) process has been used widely to produce high-performance alloys dedicated to critical application, such as hot work tool steels, nickel base alloys, the manufacture of components in aerospace and landbased turbines, etc. Figure 1 shows a schematic diagram of ESR process including a consumable electrode, a molten slag pool, a liquid metal pool, a solidified ingot, and a water-cooled mold. Alternating or direct current flows from the electrode to the water-cooled baseplate through the high resistivity calcium-fluoride-based molten slag which result in Joule heating and Electromagnetic force (EMF). Part of the Joule heating melts the electrode and the droplets travel through the slag and accumulate the liquid metal pool. The electrode is continuously advanced into the slag as it melts to build up an ingot of improved structure and composition by controlled solidification and chemical refinement. The metallurgical properties of the remelted ingot are really related to the solidification structure, which strongly depends on magnetohydrodynamic, thermal, and solidified behavior in the molten slag, liquid metal pool, and mushy zone."

Jan 1, 2014

By R. M. Reynolds

Engitec Impianti, S?.p.A. of Milan, Italy has successfully designed, constructed and has in operation state-of-the-art battery breaker systems at two European locations. A third facility i:s partially completed in Toronto, Ontario, Canada. The CX system crushes whole batteries, separates the various components and desulfurizes the battery paste. The system also produces sodium sulfate from the sulfuric acid and lead sulfate contained in the batteries. Actual plant operating data indicates that the desulfurized paste contains less than 0. 6 percent sulfur and less than 0. 5 percent antimony. The CX system utilizes mechanical screening and an up-flow hydrodynamic separator to accomplish the component separation. Sodiwn hydroxide or sodium carbonate is used for desulfurization. The sodium sulfate brine is evaporated and crystallized to produce clean anhydrous sodium sulfate suitable for use by detergent or glass manufacturers. Plant data also indicates that an increase in furnace productivity of about 25 to 30 percent is achieved using feed from the CX system. The desulfurized paste is very suitable for electrolytic processing as an alternative to pyrometallurqical processing.

Jan 1, 1990

By Young-Sool Jin, Heung Nam Han, Hong Joon Kim, Jae Kon Lee

A mathematical model was developed considering non-symmetric cooling' and stress distribution in both thickness and width direction of strip on a run-out table of hot strip mill. In order to solve a transient heat transfer equation including the heat evolved from phase transformation, a finite element method coupled with thermodynamic and kinetic analyses was applied. The heat capacity of each phase and heat evolution due to phase transformation were obtained from the thermodynamic analysis of the Fe-C-Mn-Si system based on a sub lattice model. The phase transformation kinetics of the steels was derived by using an inverse additivity technique with continuous cooling experiments. Heat transfer coefficients of strips on the run-out table were, by applying an inverse method, determined from the actual mill data under various cooling conditions. As for the stress analysis, the density change of strip due to cooling and phase transformation, and the transformation superplasticity were considered. A 90nstitutive equation for the transformation superplasticity, which is related to the phase transformation kinetics and the internal stress due to the density change of strip, was applied. A finite element method was adopted to calculate the deformation behaviour of strip on a run-out table of hot strip mill. Using the models, the temperature-phase-deformation history and distribution of a strip on the run-outtable was calculated.

Jan 1, 2001

By Dong Liang, Honggang Zhong, Zhenxing Yin, Qijie Zhai

"2507 super duplex stainless steel (SDSS) has been widely applied in a marine environment, attributing to its excellent pitting corrosion resistance and mechanical properties which are particularly determined by the nitrogen precipitation behaviors and volume fraction of ferrite. In this paper, various cooling rates were obtained by applying four different moulds with the common gating system. By which the influence of cooling rates on nitrogen precipitation behaviors and the ferrite fraction in cast 2507 SDSS was comparatively investigated. The results showed that nitrogen porosity could easily precipitate in cast 2507 SDSS under standard atmospheric pressure. The number of nitrogen holes increased with decreasing the cooling rates, and the holes mainly distributed in three zones, i.e. the interface between the horizontal and vertical columnar grains, top vertical columnar grains and the final solidification region. Additionally, higher ferrite fraction was obtained with lower cooling rates.IntroductionDuplex stainless steels (DSS) have a dual-phase microstructure consisting of ferrite (d) and aus-tenite (?). Due to the combined advantageous properties of d and ? phase, their application rapid-ly increased in industry [1, 2]. Super duplex Stainless Steel (SDSS) is the third generation of du-plex stainless steels, of which the alloy elements Cr, Ni and N content are higher than the stand-ard 2205 DSS. Because it has high contents of alloy elements, the SDSS has better mechanical properties, and its pitting resistance equivalent number (PREN) reached a point 43. Hence SDSS has been used in petroleum chemical industry, the marine equipment and harsh corrosion environments [3]. SDSS contains ferrite stabilizing elements, such as Cr, Mo and Si, and austenite stabilizing elements like Ni, Mn and N [4]. Many researchers have studied the effects of these elements on the stabilization of d and ? phase and the ratio of the two phases. High nitrogen con-tent is another prominent feature of SDSS. Nitrogen addition to SDSS is very effective for improving its mechanical properties [5] and corrosion resistance [6], such as pitting resistance in NOx environment. To increase the nitrogen content in steels, a lot of work had been done. N. Nakamura and S. Takaki [7] examined the behavior of nitrogen absorption in Fe-23Cr alloy powder by sintering in nitrogen gas atmosphere, they found nitrogen content easily up to 1.0 wt. %. Using devised NH3 gas injection system, W. Park et al. [8] successfully produced austenitic Fe–23.5Cr alloys containing over 3 wt. % of nitrogen. Further-more, W.P. Tong et al. [9] stated that nitrogen percent was extraordinary high (about 10 wt. %) in pure iron plate. However, the above methods are difficult to be applied to large-scale industrial production."

Jan 1, 2012

By Jafar Safarian, Merete Tangstad, Leiv Kolbeinsen

"Silicon and its binary alloys have several applications in metallurgical, chemical, photovoltaic and semiconductor industries. Silicon goes to its liquid state within its production, refining and when it is alloyed with other elements. Therefore, the characterization of silicon melts thermodynamics is important and useful. The liquidus and activities in several silicon binary systems have been recently calculated by the application of two liquidus constants, which were established using the experimentally determined liquidus data. In the present study, the thermodynamic properties of six silicon binary melts, which are simple eutectics, are calculated by analytical approaches. In this case, the changes in the partial and integral Gibbs free energies and enthalpies of mixing are calculated and compared with the experimental data in literature. The enthalpies are calculated by two methods and the calculation results are compared to the data from the literature. It is shown that thermodynamic properties of silicon binary melts can be accurately predicted without the use of complicated thermodynamic software.IntroductionSilicon and its alloys have several industrial applications. Silicon is used for making aluminium-silicon alloys to produce cast parts, mainly for automotive industry. Silicon in the form of ferro-silicon is used to deoxidize and alloy steel and cast iron. The photovoltaic (PV) industry has had a rapid growth in the recent years and silicon is the dominant material used for the fabrication of solar cells. Silicon is primarily produced through carbothermic reduction of quartz in electric arc furnaces and the produced metallurgical grade silicon (MG-Si) contains around 1 wt% impurities. It is further refined to produce solar grade silicon (SoG-Si) with above 99.9999 wt% Si to fulfil the chemical requirement for PV application. Since molten silicon is processed all along the metallurgical route, obtaining fundamental thermodynamics knowledge about silicon melts is valuable for the related industries."

Jan 1, 2012

By Susumu Okabe

Injection metallurgy is widely adopted in various fields of metallurgical operations to achieve high productivity. The Mitsubishi Continuous Copper Smelting and Converting Process employs the top blown lance technique for the continuous supply of solid charges and reaction gases into the molten bath, where the agitated bath contributes to enhance the heat and mass transfer and the increased gas/liquid interface area accelerates the reaction. However, excessive splashing of the molten materials accompanied by the injection may cause an unexpected wear of the furnace lining. In order to estimate the splashing rate quantitatively, and to optimize the furnace design and the blowing condition, a physical model study of the top blown gas injection onto the liquid bath was carried out. An equation of the splashing rate was obtained as the function of cavity size, gas velocity and bath properties.

Jan 1, 1995

By Garg. D.

Premixed bronze powders are widely used to produce a wide variety of P/M components including bearings and bushings by the powder metal industry. The physical and mechanical properties of sintered bronze components such as dimensions, strength, microstructural characteristics, and sintered density are well known to change with sinlering furnace design, particle size distribution in powders, green density, preheating and sinlering time" and temperature, and protective atmosphere flow rate. " However, not much is known about the effect of protective atmosphere composition on physical and mechanical properties of sintered bronze components; This paper describes effects of protective atmosphere composition and sintering temperature on physical and mechanical properties of sintered bronze components

Jan 1, 1996

By S. Yin, A. Bogno, H. Henein, P. Natzke

Impulse Atomization (IA) (a single fluid atomization technique) was used to rapidly solidify Al- 4.5wt%Cu and Al-4.5wt%Cu-0.4wt%Sc under argon atmosphere. In addition to the IA-generated droplets, the same technique was used to produce strips by Spray Deposition (SD) of the same alloys on a copper substrate with and without oil coating. The rapid solidification microstructures were analyzed using Scanning Electron Microscopy (SEM). From the SEM images, the amount of eutectic and the secondary dendrite arm spacing (SDAS) were measured. These SDAS results lead to the estimation of cooling rate. The eutectic fraction coupled with the metastable extension of the solidus and liquidus lines of Al-Cu (Sc) phase diagram lead to the estimation of primary and eutectic undercoolings. A comparison of the solidification path of the droplets and the strips was done as well as the analysis of the effects of scandium.

Jan 1, 2015

By Wiraseranee. Chompunoot, Kazuki Morita, Toru H. Okabe

"Aiming at the development of more effective recycling processes, dissolution behavior of rhodium into molten slag was investigated. Using a pure rhodium crucible and Na2O-SiO2 slag system, equilibration experiments were carried out for 18 h at 1423-1623 K under various oxygen partial pressures of 0.005-1 atm with varied slag basicity. Rhodium solubility increased with increasing oxygen potential, slag basicity, and temperature. Rhodium dissolved into slag as rhodate ion ([RhO2]-) by the endothermic reaction: Rh(s) + 3/4O2(g) + 1/2O2-(in slag) = [RhO2]-(in slag). In the dissolution reaction, the “rhodate capacity” of slag is newly-defined. The correlation between rhodate capacity and optical basicity is reported.IntroductionDue to its high chemical resistance and outstanding catalytic properties, rhodium (Rh), one of the platinum group metals (PGMs), is utilized in various applications such as catalysts, molten glass vessels and containers, and electronic devices. Owing to the rarity of Rh resources in nature, recycled Rh from scraps such as spent automobile catalytic converters is currently considered as an important source of Rh supply [1]. According to the recycling practices, Rh is currently mainly recovered from scraps along with other PGMs such as platinum (Pt) and palladium (Pd) by a dry process (e.g., smelting), a wet process (e.g., leaching and subsequent separation of PGMs from aqueous solution), or a combination of both processes [2]-[4]. Among these processes, smelting is commonly applied because PGMs can be effectively separated from a relatively large amount of various impurities coexisting in scraps. In the smelting process, Rh and other PGMs are collected in the collector metal (e.g., iron and copper), and impurities in scraps are removed into slag [4]-[6]. The process may be carried out at a temperature range of 1573-1973 K, in either an oxidizing or reducing atmosphere. Due to the high oxidation resistance at high temperatures, Rh is expected to be collected efficiently in the metal collector rather than being oxidized and forming RhOx in a molten slag. However, Rh loss into slag does occur in this process [7]."

Jan 1, 2011

By Marco Antônio Siqueira Rodrigues

The possibilities for treating rinse waters fiom chromating bath by electrodialysis are discussed together with the possibilities of optimizing the treatment process for waste reduction and reuse of water and chemical products. An industrial effluent with 4600 ppm of Cr(VI), besides other metallic contamination, was used as work solution. This solution has been recirculated on an electrodialysis cell of three compartments, using exchange membranes Selemiom AMT and CMT. A migration of dichromate ions into the anodic compartment was obtained, so that an extraction of circa 99.9 % of Cr(VI) present on the solution was observed, resulting in water with a Cr(V[) concentration of 4 rnd. These results show that electrodialysis can be used to treat these effluents, and this water could be reused as rinse water. The solution of the anodic compartment, consisting at the beginning of the experiment of H2S04, 0.1 N, reached 7200 mg/l of Cr(VI). This concentrate could be reused on the chromating bath itself.

Jan 1, 1999

By N. Choi

The distribution behavior of selenium and tellurium in nickel sulfide smelting was investigated in the temperature range of 1250-1300 °C under an inert gas atmosphere and various oxygen partial pressures. The distribution coefficients of selenium and tellurium between nickel-copper-iron matte and silica-saturated iron silicate slag were detennined in terms of matte and slag compositions, temperature, and oxygen partial pressure. The effect of slag additives such as CaO, MgO, and Ah03 on the distribution coefficients of those elements was also investigated. It was observed that the distribution coefficients of selenium and tellurium increased with increasing matte grade and temperature. The solubility of selenium and tellurium in the slag decreased with increasing the partial pressure of oxygen within the range investigated in this study. The distribution coefficients of selenium and tellurium increased with the amount of CaO and MgO. Tellurium distribution coefficients also increased by the addition of Ah03. Meanwhile, the addition of Alz03 decreased the distribution coefficients of selenium at high matte grade.

Jan 1, 1996

By Ali P. Gordon, James Williams

Joints gasketed with viscoelastic seals often receive an application of a secondary torque, i.e., retorque, in order to ensure joint tightness and proper sealing. The motivation of this study is to characterize and analytically model the load and deflection re-torque response of a single 25% glass-fiber reinforced polytetrafluorethylene (PTFE) gasket-bolted joint with serrated flange detail. The Burger-type viscoelastic modeling constants of the material are obtained through isolating the gasket from the bolt by performing a gasket creep test via a MTS electromechanical test frame. The re-load creep response is also investigated by re-loading the gasket after a period of initial creep to observe the response. The modeling constants obtained from the creep tests are used with a Burger-type viscoelastic model to predict the re-torque response of a single boltgasket test fixture in order to validate the ability of the model to simulate the re-torque response under various loading conditions and flange detail.

Jan 1, 2015

By Yanlong Li, Lifeng Zhang, Ying Ren

In this work, a multiphase mathematical model for the fluid flow in argon-stirred steel ladles was established and validated by experimental measurement of wood's metal. Alloy dispersion in the molten steel was calculated. The melting and mixing of alloy was faster with smaller size of the alloy particles, larger superheat and bigger slip velocity. The current mixing time is approximately 300 s with 30 mm alloy diameter and 91.5 K superheat.

Jan 1, 2014

By Jiangwei Shen, Cong Wang, Haibin Zuo

The research on the formation of Silico-Ferrite of Calcium and Aluminium (SFCA) in the process of cooling and solidification is rarely reported. The crystallization process was observed by using scanning electron microscopy (SEM) and optical microscope in this paper. The effect of different cooling system on the microstructure and phase composition of the sinters was investigated to obtain the appropriate cooling rate to improve the metallurgical properties of sinters. The experimental results show that the crystallization of calcium ferrite is getting better when the cooling rate is decreased from water quenching to cooling in the air. There are a large number of hematite phases with interconnected crystal structure in the sample cooled in the air. In the case of the compressive strength, it was determined by the mineral composition and pore structure, higher SFCA and hematite contents in sinter cooling in the air lead to a higher strength. Glass phase in the water quenching sinter was the major reason for the lowest strength. High porosity contributes to a decrease in compressive strength for the sinter cooling in the furnace. Therefore the air cooling was the appropriate cooling rate to achieve high quality sinter under this experimental condition.

Jan 1, 2016