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By W. D. Cho

The slag chemistry in steel processing plays an important role in terms of the removal of impurities including alumina particles. In the present study, the dissolution of solid alumina particles in CaO-based fluxes at the temperatures between 1450 and 1550 °C has been investigated to determine dissolution kinetics and mechanism. Alumina particles were added directly in the slags and the size of alumina particles was measured as a function of time using optical and scaru;ling electron microscopes. The dissolution rate has also been obtained as a function of Si02, CaF2, MgO and MnO contents in the slags. The diffusion boundary layer between alumina and bulk slag phase has been observed and analyzed using SEM and EDX. In addition, some experiments have been performed for the dissolution of alumina in BaO-based fluxes.

Jan 1, 2003

By Xin-liang Gao, Qing Li, Gui-qin Fu, Duo Jin, Miao-yong Zhu

"Optical microscope together with alternative wet-dry cyclic accelerated corrosion tests and XRD, SEM were employed on bridge weathering steel samples with different Mn and Ni contents which were vacuum induction melted and rolled to study their effects on the microstructure and rust layer evolution in er' containing condition. The results show that the microstructure is mainly ferrite and pearlite when Mn and Ni contents are 0.75 %, 0.42 %, respectively. Both the increase of Mn and Ni contents will make pearlite disappear while granular bainite appear, meanwhile the grain size decreases. With the increase of Mn content, the corrosion rate decreases in the initial stage, but the effect becomes little in the later stage. The increase of Ni not only improves the corrosion resistance of steel base at the initial stage but also hinders the tendency of further corrosion. As Mn content increases, a-FeOOH contents in rust layer decreases. With increase of Ni content, the content of a-FeOOH in the rust increases while that ofy-FeOOH decreases.IntroductionWeathering steels had been ~radually applied in manufacture of bridges owing to reducing the corrosion rate remarkably [I- l .Good weldability was needed for high performance bridge weathering steels. Since carbon was thought to be bad for weldability, low carbon content steel was adopted and Mn was added to amend the mechanical strength loss. Some scholars[6, 7l believed that Mn was beneficial for increasing corrosion resistance performance of the steel in marine atmospheric environment. Some scholars [S, 9l thought that Mn had little effect on corrosion resistance in marine atmospheric environment. Presently, the effect of Mn on bridge weathering steel in marine atmospheric environment still remained poorly understood. Ni was considered to be beneficial for increasing corrosion resistance performance in marine atmospheric environment [JO-l4l However, the high cost limited its application range. What would bring to the rust and corrosion by decreasing Ni content needed further research.Most researchers assumed that microstructures only affected the corrosion behavior of bare steel. But the study of Guo et al. P5l showed that the homogenous microstructures were beneficial for the corrosion resistance of steels. The effect of Mn, Ni content change on microstructure and microstructure on corrosion still remained poorly understood. In the present work, the effect of Mn and Ni on the microstructures of steel matrix, as well as the microstructures on the rust and corrosion was investigated."

Jan 1, 2014

By Rey B. Marquez

This paper introduces and outlines the implementation of Reliability Centered Maintenance (RCM) at Phelps Dodge Hidalgo Inc. By using a disciplined approach to the everyday maintenance functions, a proactive strategy is being developed which "raises the bar" for plant maintenance. The main objectives are: integration of Operations and Maintenance partnerships, transformation of maintenance practices from a reactive to proactive mode through the introduction of a progressive Predictive/Preventive Maintenance program (PDM/PM) paradigm changes, increased management support of maintenance functions, introduction of new indices and root cause analysis, updated; training, and definition of RCM components. RCM is the vehicle being utilized to reach the higher level of equipment availability and utilization. However, the ultimate goal is to venture beyond RCM and into the new frontier of Total Maintenance Management (TMM).

Jan 1, 1998

By David C. Lynch

FeCl3 particulate of 10 to 100 um in diameter was reacted with radicals produced in an oxygen plasma at pressures between 1 to 20 Torr. The particulate, in a fluidized bed, was positioned above the plasma to avoid over heating the oxide product which is known to lead to crust and clinker formation[ 1 ]. Reaction between the iron chloride and the gas phase occurred at temperatures between 66 and 226 °C. Oxygen radicals react with the surface material to a depth of approximately 2.5 4m. Surface material, analyzed with a x-ray technique, indicates that the maximum amount of FeCl3 reacted on a weight basis was found to be approximately 67%. More typically, 40 to 50 wt% of the chloride was reacted within 30 minutes to 1 hour.

Jan 1, 1996

By I. Gaballah

The electrochemical behavior of a chalcopyrite concentrate having a high pyrite content was studied in HC1 by potentiodynamic, potentiostatic and galvanostatic experiments using a cell having separate anodic and cathodic compartments. Anodic oxidation of chalcopyrite particles was realized both by their contact with the cunent feeder and by reaction with ferric and cupric ions. An increase of current leads to a more selective dissolution of chalcopyrite. Surface passivation was observed after an electrolysis time related to the cell current. Cathodic reduction of chalcopyrite concentrate seems to be more promising. Almost complete conversion of chalcopyrite to a copper sulfide (Cui.8.S) is observed, whereas no reaction of the pyrite was detected. This confirms the possible selective dissolution of copper from the chalcopyrite concentrate. Copper sulfide obtained by cathodic reduction was leached using a cupric chloride solution.

Jan 1, 1994

By Dinesh Goyal

Industrial fly ash from (electro static precipitator) was mixed with soil at different levels on v/v basis for raising of pulpwood tree species. In field trials conducted on degraded soils increase in the plant growth of Eucalyptus tereticornis, Acacia auriculiformis and Casuarina equisetifolia by 10 %, was observed during the initial six months after plantation at 18-24% (v/v) fly ash concentration which was at par with chemical fertilizer treatment. Level of As, Se and Mo in flyash was 6.2, 3.6 and 4.0 ppm respectively. The radioactivity analyses 40K, soil and 28 fly ash showed that the activity levels of gamma emitting radionuclides K, Ra, Ac were within the permissible limits and mixing of fly ash with soil at tested concentration would have no deleterious effects. Available Co, Cr, Ni and Cd in rhizospheric soils were below detection limit. Fly ash at 10-20 % level (v/v) was also found to be a good potting mix material in forestry nurseries in terms of improving biomass production by 20 %, when tested in nursery seedlings of Eucalyptus tereticornis. Nursery addition of fly ash in soil decreased soil dehydrogenase activity and the soil bacterial population was negatively affected. These results indicate that use of fly ash in forestry sector involving nursery and plantations as a soil amendment agent upto 10-20 % v/v is a gainful utilisation of fly ash.

Jan 1, 2002

By Ajit Kumar Jaiswal

"Electric Arc Furnace (EAF) being a power-intensive equipment, EAF based industries are highly dependent on scarce electric energy. This is the reason Government of India is highly concerned about this and laid emphasis on the conservation of electric energy.This paper highlights factors contributing to reduction in specific electric energy consumption in EAF and suggests measures not only for power saving, but also for productivity improvement. To name a few, these are proper sealing of furnace, introduction of oxy-fuel burners, foamy slag practice, increased usage of hot metal/DRI, post-combustion of CO gas for preheating of scrap, improved selection & design criteria of electrics, power demand management, and process automation. Few cases also have been cited, where the above measures have helped in reaping significant benefits.IntroductionFor a long time, Government of India had focused on increase in energy supply, in particular, through electricity generation. Now the emphasis of Government of India has shifted from electricity generation to its conservation for following two reasons:??Power plants have become very cost-intensive??By saving energy, more of it can be delivered at lower cost to the consumersPower generating units, transmission & distribution agencies as well as consumers all have roles to play in the area of energy conservation. By energy conservation, we mean curtailing energy requirement by reducing energy wastages and taking up measures to improve energy efficiency of electric equipment/appliances. In almost all cases, this would be economically beneficial.India’s cost-effective energy conservation potential has been estimated by the Planning Commission at 23 per cent of total commercial energy generated ?1?. A national movement for energy conservation can significantly reduce the need for fresh investment in energy supply systems in coming years. It is imperative that we make all-out effort to realize this potential. Whether a household or a factory, a small shop or a large commercial building, a farmer or an office worker, every user can and must make this effort for his own benefit and for the nation’s benefit as well."

Jan 1, 2009

By H. Senoh

For the purpose of clarifying the reason caused a drastic decrease of discharge capacity for MmNi3.6Mn0.4Al0.3Co0.7 electrode at relatively low temperatures, various factors influencing the charge-discharge processes were investigated in the temperature range of 25°C to -40°C. The charge efficiency obviously decreased at low temperatures less than 0°C due to a decrease in the rate of the charge-transfer reaction on the electrode surface. Moreover, both the rate of the hydrogen diffusion from the alloy bulk to surface and the rate of the charge-transfer reaction significantly influenced the high-rate dischargeability. The addition of Mo to MmNi3.6Mn0.4Al0.3Co0.7 alloy was found to be effective for improving the electrocatalytic activity, leading to the improvements of the charge efficiency and the high-rate dischargeability at relatively low temperatures.

Jan 1, 2002

By Nourreddine Menad

Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount to 30 percents of the scrap mass. Generally, they are treated with flame retardants such as halogenated ones and they can result in different toxic chemical compounds. These plastics can be used as combustibles in the recovery of copper and precious metals. However, during their combustion, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. The estimated thermodynamic data of several organic compounds resulting from combustion of electric and electronic scrap, have been used in conjunction with the program HSC to calculate the conditions for dioxin and furan formation. The results show that the formation of the dioxins is dependent on the quantities of carbon, hydrogen, chlorine and oxygen reacting in a given system, as well as on parameters such as temperature and pressure.

Jan 1, 1998

By Tom W. Gonzales

Magma Metals Company commissioned a 3000 tpd Outokumpu flash smelting furnace in July 1988. Through September 1992 the PSP has smelted a first campaign record 4.1 million tons of concentrate. This paper discusses modifications made to the original process equipment to overcome design flaws as well as future design changes currently under consideration.

Jan 1, 1993

By Z. Y. Xie

The visualization techniques were employed for the analysis of computer simulation studies of dislocation core structure in ordered alloys. Atomistic computer simulation was used for the study of the local configuration of the material in the vicinity of the dislocation. Stresses were applied in the simulation in order to study the necessary stress level for the dislocation to move and onset plastic deformation of the material. The results were analyzed in terms of the strain tensor as a function of the position (x, y) in the material with the dislocation located at (0, 0). Various visualization packages are used to plot the invariants of this strain tensor and to visualize the changes that the dislocation core undergoes under stresses until it finally moves.

Jan 1, 1993

By H. Deveci

Bioleaching/biooxidation is essentially a dissolution process with the involvement of acidophilic bacteria acting as the "catalyst" to accelerate the dissolution of metals from sulfide minerals. The contribution of bacteria to the metal dissolution is closely controlled by the growth of bacteria, which is itself affected by the physico-chemical conditions within the bioleaching environment. There are a number of operating parameters controlling bioleaching processes, which are required to be maintained within a certain range in the leaching environment whereby the activity of bacteria with the resultant oxidation of sulfide minerals can be optimized. In this regard temperature, acidity, oxidizing conditions, availability of nutrients, oxygen and carbon dioxide, surface area and presence of toxic ions are of prime importance for control and optimization of bioleaching of sulfide ores/concentrates. Bioleaching processes are temperature and pH dependent with optimum metal dissolution occurring in a particular range where the bacterial strain is most active e.g. mesophiles at 35-40°C and pH 1.6-2.0. Provision of nutrient salts is required to maintain the optimnm growth and hence metal dissolution with the quantity of nutrients apparently being dependent on the availability of substrate i.e. head grade/pulp density of an ore/concentrate. Oxygen transfer is one of the most critical factors since the oxygen levels below 1-2 mgll may adversely affect the oxidizing activity of bacteria. Bioleaching rate tends to improve with increasing the surface area at low pulp densities but, in practice. the pulp density is limited to -20010 w/v. Increasing concentrations of ions such as cr may also adversely affect the oxidative activity of bacteria. Keywords: Bioleaching, Biooxidation, Acidophilic bacteria

Jan 1, 2003

By Shengli Wu, Mingyin Kou, Feng Chang, Laixin Wang, Hua Lu, Jianliang Zhang

Sintering dust has been regarded as an important secondary resource in a modern steel plant. Sintering dust was mechanically treated using different milling machines and experimental conditions in air atmosphere. The changes in phase constitution, particle size, specific surface area, particle morphology, and lattice parameters of activated sintering dust were determined. It was found that the agglomeration of the particles take place during extended dry milling with accessible pores for Nitrogen gas. The maximum specific BET surface area in the stirring wet grinding and planetary wet grinding increases to 43.06 and 46.45 m2/g after activated 360 min respectively. With the increasing of energy input, the intensity of diffraction peaks of dolomite and hematite gradually decreased. Furthermore, the previous phase almost disappeared eventually under any experimental conditions. In addition, Fourier transform infrared spectroscopy indicates that organic matter and carbonate decompose easier than other phases, especially under stirring wet milling.

Jan 1, 2016

By Jacob Bummer, Greg Roset, Dayle Flynn

"IntroductionStillwater Mining Company operates a Precious Metals Smelter (PMS) located in Columbus, Montana USA. The PMS processes iron, copper, and nickel sulfide bearing concentrates containing platinum, palladium, gold, and rhodium. The concentrates are produced from two mines in the Beartooth Mountains located in south central Montana. The PMS utilizes a 7.5 megawatt 3-in line electric furnace to smelt the concentrates, and two Top Blown Rotary Converters (TBRC's) to remove iron. In addition to the mine concentrates, the PMS also processes various forms of Platinum Group Metal (PGM) bearing recycled catalyst. The sulfide matte produced within the electric furnace and TBRC's acts as a collector for the PGMs. Throughout the operation of the PMS, there are three different forms of molten material that are processed through the Stillwater Granulation system: TBRC matte, TBRC slag, and electric furnace matte. This paper describes the operation of this granulation system.Tapping the FurnaceWhen a sufficient level of molten PGM bearing matte has been reached within the inner volume of the electric furnace, the molten material is ""Tapped"". Tapping requires drilling into the electric furnace until reaching the molten matte phase. The matte phase will drain out of the drilled hole through a graphite launder into a 5 ton refractory lined ladle. Once the ladle is full, the tap is plugged with a mud gun."

Jan 1, 2012

By M. Jahazi, P. P. Bhattacharjee, K. Chadha

The present work investigated the effect of strain reversal during high pressure torsion on the evolution of microstructure, texture and hardness properties of two different materials with different dynamic recovery behavior, namely, high purity (99%) Aluminum (2N-Al) and Aluminum-Magnesium (Al-2.5%Mg) alloy. In the two aluminum alloys subjected to different routes, the evolution of the ultrafine structure followed same trend. At lower strain level, sub grains with prominent LAGBs network were observed and at higher strains, ultrafine equiaxed grains separated by HAGBs were observed throughout the disk. The texture evolution in monotonically and strain reversal processed 2N-Al and Al-2.5%Mg showed presence of typical torsion texture components at different strain levels. The strength of the components was observed to follow different trends depending on the processing routes.

Jan 1, 2015

By W. D. Cho

The slag chemistry in steel processing plays an important role in terms of the removal of impurities including alumina particles. In the present study, the dissolution of solid aluimina particles in CaO-based fluxes at the temperatures between 1450 and 1550 °C has been investigated to determine dissolution kinetics and mechanism. Alumina particles were added directly in the slags and the size of alumina particles was measured as a function of time using optical and scanning electron microscopes. The dissolution rate has also been obtained as a function of Si02, CaF2, MgO and MnO contents in the slags. The diffusion boundary layer between alumina and bulk slag phase has been observed and analyzed using SEM and EDX. In addition, some experiments have been performed for the dissolution of alumina in BaO-based fluxes.

Jan 1, 2003

By Masanori Abe, Yoshitaka Kitamoto, Kazuhiro Nishimura

"Ferrite plating is a chemical processing which utilizes Fe2+ - Fe3+ oxidation to synthesizing polycrystalline films of ferromagnetic spinels (MFe20 4, M = Fe, Co, Ni, Zn, Al, Cr, TI, etc:) directly from an aqueous solution at 24 - 100°C. This low temperature process allows us to fabricate new ferrite film devices on · substrates of such non-heat-resistant materials as plastics, GaAs integrated circuits, and biomaterials. Synthesized from an aqueous solution the ferrite plated ·films are highly biocompatible. Thus various magnetic device and biomedical applications have been proposed and realized using ferrite-plated films. Ferrite-encapsulated polymer microspheres are applied to antibody carries for enzyme immunoassay, and also to toners/carriers for photocopying. Perpendicular magnetic recording media utilizing plated CoNi ferrite films are proposed. The low-temperature synthesized films of NiZn and Co ferrites are potentially used as soft-magnetic and/or insulating layers, respectively at high/microwave frequencies.IntroductionFerrite plating is a processing which facilitates the formation of crystalline spinel ferrite films with various compositions, (Fe, M)30 4 (M = Fe, Co, Ni, Zn, Al, Cr, TI, etc.), directly from an aqueous solution at 60 - 100°C [1]. This opened the door to fabricating novel ferrite-film devices using substrates of such non-heat-resistant materials as plastics and GaAs integrated circuits [2-4]; conventional ferrite film preparation techniques such as sputtering, vacuum evaporation, MBE, LPE, etc., require high temperatures(> -600°C) for crystallization of ferrites, which deteriorates the non-heat-resistant substrates. Recently we extended ferrite plating to be preformed at room temperature [5, 6]. This enables us to use as substrates such organic materials as biomaterials (e.g. enzymes) having very low heat-resistance."

Jan 1, 2000

By Shufeng Yang, Anping Dong, Yongfeng Chen, Jingshe Li, Lifeng Zhang, Liyuan Sun

"Instead of nickel-based stainless steel, a nitrogen-bearing stainless steel was produced to reduce the production cost stemming from the shortage of nickel recourses. Thermodynamic model to calculate the saturation nitrogen content in the stainless steel were developed and the model was validated by experimental measurement. The experiments were performed with a high temperature induction furnace. Nitrogen gas under constant pressure was injected into the crucible with a top lance by which the nitrogen was transferred to the molten stainless steel. The effects of chemical composition, temperature, superficial active elements and nitrogen-flow rate on transferring nitrogen to the steel were investigated and discussed.IntroductionWith the rapid production growth of stainless steels, nitrogen-bearing stainless steel has recently attracted more and more attention for their high strength and excellent corrosion resistance imparted by interstitial nitrogen without decreasing its toughness and ductility. Moreover, the addition of nitrogen to the stainless steel as a substitute for nickel leads a lower consumption of nickel, so significantly lowers the high production cost stemming from the shortage of nickel recourses. However, production of the nitrogen-bearing steel is difficult since nitrogen is a gas element and has a low solubility in the steel. So efficiently increasing the amount of nitrogen in steel continues to be one of the main concerns for the production of nitrogen-bearing steels.Currently there are some special processes to produce austenitic stainless steels with a very high N content, including pressurized electroslag remelting, counter-pressure casting, special induction melting and powder metallurgy, etc [1]. Special expensive vacuum system was required for these processes. Alloying nitrogen at a normal pressure can be performed by alloy addition or gas injection. Blowing nitrogen gas is a more economic and advisable method since the nitrogen-bearing alloy is quite expensive and contains high content of impurities. A number of investigations have been reported on the solubility of nitrogen gas in pure iron [2] but few in iron-based multi-component alloys such as stainless steel.In the current study, the effects of steel chemical composition, temperature, superficial active elements and nitrogen-flow rate on transferring nitrogen to the steel were experimentally investigated with a high temperature induction furnace."

Jan 1, 2011

By Kuo En Chang

Many rare earth - transition metal (RE-TM) compounds absorb/desorb hydrogen reversibly at room temperature and atmospheric pressure. For LaNi5 which is used as a battery material, the electrochemical nature of this process is well known. In the case of Nd-Fe-B which has found wide application as a powerful permanent magnet, the absorption of hydrogen has both significant advantages and disadvantages. However, a fundamental understanding of the hydrogenation process at ambient temperatures and its effect on subsequent corrosion behavior is currently lacking. This paper reports the results of the hydrogenation of NdFeB two alloys, (NdDy)15Fe78.3A10.7B6 and (NdDy)15Fe67Co5V4A12B7, which are compared with that of LaNi5. Results show that hydrogenation can be accomplished by either electrochemical methods or immersion in dilute sulfuric acid. For the latter method, the change in lattice parameter indicates that the level of hydrogen absorbed by the NdFeB particles corresponds fairly closely to an overall composition of Nd2Fe14BH2.7. Cyclic electrochemical charge/discharge experiments show that the maximum hydrogen discharge capacities of the NdFeB, NdFeB-Co-V, and LaNi5 are 40, 60, and 210 mA?h?g-1, respectively. Anodic potentiodynamic polarization measurements and calculated values of icon reveal that absorbed hydrogen in NdFeB-Co-V and the NdFeB may lead to significant increases in corrosion rates.

Jan 1, 1995

By Li Xi

This paper describes how a back-propagation neural network is built for predicting the properties of engineering materials from their other properties, compositions or processes. A predicted result of the impact toughness of a 12Cr-2Ni-1.5Mo stainless steel from its tempering temperature is presented. Furthermore, the combination of this neural network for prediction is able to supplement the unpredictability of the expert system outside its domain of expertise. An integrated system may perform more intelligently and solve more complex problems as well as human expert, in some case even better.

Jan 1, 1992