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By Regina Krachler, Herbert Ipser

"The principles of the derivation of statistical-thermodynamic models to interpret the compositional variation of thermodynamic properties in non-stoichiometric intermetallic compounds are discussed. Two types of models are distinguished: the Bragg-Williams type, where the total energy of the crystal is taken as the sum of the interaction energies of all nearest-neighbor pairs of atoms, and the Wagner-Schottky type, where the internal energy, the volume, and the vibrational entropy of the crystal are assumed to be linear functions of the numbers of atoms or vacancies on the different sublattices.A Wagner-Schottky type model is used for the description of two examples with different crystal structures:For B'-FeAl (with B2-structure) defect concentrations and their variation with composition are derived from the results of measurements of the aluminum vapor pressure; the resulting values are compared with results of other independent experimental methods.For Rh3~ (with an NiAs-derivative structure) the defect mechanism responsible for nonstoichiometry is worked out by application of a theoretical model to the results of tellurium vapor pressure measurements. In addition it is shown that the shape of the activity curve indicates a certain sequence of superstructures.In principle, there are no limitations to the application of statistical thermodynamics to experimental thermodynamic data as long as these are available with sufficient accuracy, and as long as it is ensured that the distribution of the point defects is truly random, i.e. that there are no aggregates of defects."

Jan 1, 1996

By Florian Kongoli

The behavior of cobalt as a by-product in the NilCu smelting and converting processes effects directly the quality of the final products as well as the revenues gained from the overall process. An effective way to evaluate and predict this important behavior is thermodynamic modeling which reduces the time and the cost of experimental investigation. In this work a thermodynamic model of cobalt-containing matte phase in NilCu smelting and converting processes is presented. The model predicts a priori the thermodynamic properties and phase relations of the ternary and multicomponent matte based solely upon the optimized parameters of the binary systems. This model can be used with other models such as those of slag, metal, gas etc. to predict various aspects of cobalt behavior such as matte- slag, metal-slag distribution, etc.

Jan 1, 1999

Proposed by outstanding electrochemist and electrometallurgist Prof. Raphael Agladze (191 1- 1989), process of copper and manganese co-electrowinning was enhanced to the pre- electrowinning stages: low,temperature co-leaching of copper and manganese containing materials, and to high-temperature co-roasting of the same materials with consecutive leaching. The report presents results of experimental investigations of the processes mentioned above, as well as results of thermodynamic investigations of co-roasting processes, and co- leaching processes computer modeling.

Jan 1, 1997

By Shawn A. Cefalu, Matthew J. M. Krane, Kent J. VanEvery

"Segregation during electroslag remelting (ESR) of a nickel-chromium-molybdenum alloy (Ni-8 wt% Cr-25 wt% Mo) has been modeled. Features of the model include species transport and AC electromagnetic effects coupled with fluid flow, heat transfer, and solidification. The effect of varying ingot diameter and melt rate, on macrosegregation patterns, local solidification time, and liquid pool profiles obtained from this model are demonstrated. The results show that the macrosegregation in the ingots correlates to the filling velocity.IntroductionElectroslag remelting (ESR) is a secondary melting process used to refine the chemical composition and the microstructure of metals. Macrosegregation of solute elements causes defects in ESR ingots, including freckles and the maldistribution of phases. These defects are not correctable through heat treatment due to the large length scales over which they occur. However, the frequency and distribution of these defects may be minimized, or even prevented, through process control based on an understanding of the conditions that lead to their formation.In the past, studies have been conducted on the effect of the process parameters on the shape of the melt pool and the thickness of the mushy zone [1-7]. In these studies, the shape of the liquid pool is determined by consideration of the heat and fluid flow induced by electromagnetic (Lorentz) force and thermal buoyancy. The transport of solute and the resultant solutal buoyancy effects were not considered in these macroscopic models. Defect formation is tied to formation of secondary phases (e.g., freckling and white spots in nickel superalloys) [5,8]. In cases where secondary phase formation is calculated (e.g., [6]), phase fractions are determined using a micro-scale model given the local solidification time (LST) and local thermal history from the macroscale model.Using the local thermal history from the macroscopic transport model to predict microstructure increases the importance of the accuracy of those results. This investigation models the macrosegregation of molybdenum during the ESR of a Ni-Cr-Mo alloy. The effect of macrosegregation on pool shape and depth is demonstrated, along with its effect on the local solidification time. By comparing the relative effects of the melt rate and ingot radius, a better understanding of the factors that affect macrosegregation, and ultimately secondary phase formation may be obtained."

Jan 1, 2004

By Shengfan Zhou, XUEWEN WANG, Fuhong Xie, Qi Ge, Bianfang Chen, Biao Liu, Mingyu Wang, Sheng Huang

To recover iron, titanium, vanadium and chromium from vanadium bearing titanomagnetite, a process of direct reduction has been proposed. After magnetic separation, a material containing titanium, vanadium and chromium was obtained. In this paper, a salt-roasting process was proposed to extract vanadium and chromium from the material containing titanium, vanadium and chromium. The effects of the several parameters that included roasting temperature, roasting time and the addition of sodium carbonate were investigated. Under the most suitable conditions including a roasting temperature of 900 °C, roasting time of 2 h and sodium carbonate addition of 33 wt%, the leaching of vanadium and chromium reached 91.2 and 68.4%, respectively. After leaching, the leach residue can be used as the raw material for extraction of titanium.

Mar 1, 2018

By I. D. Reznik

The flowsheets of converter matte production from sulphide copper - nickel and oxide nickel ores on Severonickel and Yuzhuralnickel integrated ,;corks are given. The cobalt behaviour in electrosmelting and autogenous ore smelting, converting and converter slag cleaning is observed. A list of acticles published in the 80 th is given.

Jan 1, 1993

By Tailoka F.

Various metallurgical residues from iron and steel making processes have been treated by chlorination in excess air with hydrogen chloride gas generated from the combustion of scrap polyvinyl chloride (PVC). The residues include dust from both the electric arc and blast &maces, hydrocyclone overflow, zinc - lead blast furnace slags and dust rich in zinc and copper from copper refining. Chlorination is achieved either directly by mixing the residues with scrap PVC or indirectly in a two furnace system. In the latter, scrap PVC is combusted between 523 and 573 K in a horizontal furnace and the resulting gases are then reacted with metallurgical residues in a vertical furnace at 1166 to 1329 K. Gas chromatography, thermogravimetric measurements, XRD and AAS have been utilised to study the reactions. The recovery of non ferrous metals is as high as 80 to 90 % and only a negligible amount of iron is carried over. The optimum temperature for combustion is between 518 and 573 K. Above 600 K, the evolution of HCI is so fast that sufficient chlorination is not achieved. Analysis showed that no dioxins were present in the gases, the residues or the chlorides.

Jan 1, 1997

By Hideharu Fukunaga, Jin Pan

"The recognition of Metal Matrix Composites (MMCs) as a means of providing high specific strength, high specific stiffness, excellent wear resistance, low thermal expansion and improved high temperature properties has led to a number of new processing, not previously used for plastic and ceramic matrix composites. As a primary fabricating process, the liquid methods are the major ones, which are reviewed briefly from the view of processing terminology. One of them, squeeze casting process is the most traditional and well-developed, because it is rapid, versatile and near-net shape production of materials. Two of new squeeze casting processes are presented to offer the hardness· controlled MMC and the· functionally graded MMCs as well as a newly developed whisker preform.I .IntroductionA large number of liquid processes and techniques including semi-solid liquid process are proposed. The most primitive process is ''pressure infiltration casting” of liquid metal into the fiber preform. It is called as follows depending on pressure and its source squeeze casting (1-4) by hydraulic ram, gas pressure infiltration casting (5, 6), vacuum infiltration, centrifugal casting (7), Lorentz-force-driven infiltration (8). The pressurizing on the liquid metal requests a large and stiff equipment, so pressureless infiltration technique has been developed using K2ZrF6 flux (9,10) while the mechanical properties are not high enough, and using H2 gas with Mg alloying element called pressureless infiltration casting (11-13), spontaneous infiltration process (14) and PRIMEX (15). In those processes, no severe reaction occurred between the reinforcement and matrix molten metal. In early l 990's, the reactive processing with pressure or without pressure, in which one material is totally transformed into another of the required shape, eq. assisted oxidation, has been developed, called reaction squeeze casting (16,17), DIMOX (18) reactive infiltration casting (19,20), and in-situ process (21,22). Die casting of SiCp/Al alloy (23,24) and thixocasting of SiCp/Mg alloy (25) are also applied to produce the machine component of MMCs."

Jan 1, 2000

By R. Boom, Y. V. Meteleva-Fischer, B. Kraaijveld, H. Kuntzel

"Segregation of impurities during refining of metallurgical grade silicon (MG-Si) is an option to produce solar grade silicon (SG-Si). Directional solidification is a last step in production of SG-Si effective for removal of metallic impurities. The possibility is investigated to use metallic impurities originally present in MG-Si for removing boron and phosphorus. MG-Si has been treated using two methods: 1) alloying with calcium and 2) refining with Na2O-CaO-SiO2 slag, both by controlled cooling. The microstructure of silicon and the impurities distribution have been studied before and after the treatments. Using EPMA phosphorus and boron have been detected in 1-2 wt% concentration range in several intermetallic compounds in grain boundaries after both treatments. This observation points to a different possible mechanism of silicon refining from boron and phosphorus. Controlled cooling improves migration of phosphorus and boron to the silicide phases in grain boundaries, which can be removed by acid leaching treatment.2. IntroductionStandards for silicon solar cells and growing demand on “green” energy require economical and efficient route to the production of solar grade silicon. Refining of cheap metallurgical grade silicon is one of the promising options, where application of existing metallurgical approaches can result in cost-efficient production on industrial scale. Focus in refining is on impurities, which are most difficult to remove: B, P, Al, Ti, due to their large segregation coefficient in silicon and low vapour pressure [1]. Moreover, more environmentally friendly technology in comparison to the traditional Siemens process [2] will be in accordance with societal needs. Based on properties of common impurities in metallurgical grade silicon, alloying refining and slag refining are suggested as competitive techniques having potential effect on removal of impurities harmful for conversion of solar energy [3, 4]. Alloying with Ca followed by acid leaching was found to be effective for removal of Fe and Ti from silicon [5] and to enhance also removal of boron [6] and phosphorus [7, 8]. In the work of Inoue et al. [8] drastically increasing removal of phosphorus from silicon has been observed with an increase of Ca content and a thermodynamics-based explanation was provided. Since phosphorus has been found to condense in the secondary precipitate mainly composed of CaSi2, it can be removed together with iron and titanium by consecutive acid leaching treatment. Slag refining is one of the metallurgical methods proposed to be effective for refining of metallurgical grade silicon from boron [9, 10]. Slags with additions of the following oxides to silica have shown positive effect on removal of boron: CaO [11-13], Na2O [11,14]. Mechanism of slag refining from boron is based on oxidation of boron followed by its incorporation in the slag network [9,11]; the same mechanism is suggested for refining from phosphorus taking into account that oxides of boron and phosphorus are known as network-formers [15]."

Jan 1, 2012

By Ramana G. Reddy, Yuxiang Peng

The long-term corrosion behavior of Haynes 230 (H230) alloy in MgCl2–KCl eutectic salt was evaluated at 1273 K for 500 h in Ni crucible in argon gas. The results showed H230 alloy has good corrosion resistance. In addition, corrosion was noted to occur by depletion of Cr, which was deposited on the Ni crucible. Based on the calculation of Gibbs energy of Ni-Cr alloy and exchange current density of Cr in MgCl2–KCl, the Tafel model was constructed to investigate the corrosion potential and rate. The galvanic corrosion can be explained as the predicted results were in agreement with the experimental data.

Mar 1, 2017

By James Douglas

A century ago the AIME meeting of 1899 was held at the Palace Hotel in San Francisco California in September. For his presidential address, James Douglas presented this paper which is reprinted in full with the kind permission of the AIME. It presents an interesting comparison relating to events and circumstances in the metallurgical industries at the close of last century. Being on the eve of a new century ourselves, the Editors of this volume of the COPPER 99-COBRE 99 Proceedings considered this paper would be of general interest, hence it is included here. Douglas believed in effective interchange of technical experiences and ideas. He considered the extreme secrecy surrounding the copper works at Swansea, Wales, the world center of copper only years before the time his paper was delivered, as one key reason for its decline, (and eventual closure of all copper plants there). In his paper, the pace of developments in various sectors such as transportation (railroads, the dominant means of I transportation at the time), the iron and steel and copper industries were examined, in much the same way as one might do but on the high technology of today. James Douglas was born in Quebec City, Quebec, Canada and spent his early life there. Forced to move to the United States for family and financial reasons, he went on to become a pioneer in the new Arizona copper industry, and with luck and good judgement with his interest in the new mining properties he also became very wealthy. Douglas was an accomplished mining and metallurgical engineer. He was the first President of Phelps Dodge and helped transform the small trading company of Anson Phelps and William Dodge into a mining giant.

Jan 1, 1999

By W. G. Davenport

A flash furnace can be run many different ways. It can, for example, be operated with: (a) highly 02"enriched, ambient temperature blast and no fossil fuel (b) considerable fossil fuel and hot, slightly Or enriched blast. It can also produce different grades of matte. With all these possibilities, the flash furnace operator can benefit from any technique that will indicate the 'best' way to operate his furnace. One such technique is Excel's 'Solver'optimizationroutine#. This chapter shows how our matrices and Excers optimization.abllity can be used to optimize a flash furnace operation. The chapter sets three optimization goals: (a) minimum industrial oxygen + oil cost, $ per tonne of concentrate (b) maximum smelting rate, tonnes of concentrate per hour (c) maximum profit, $ per hour.

Jan 1, 2001

By M. B. Sizgoric

Quantitative mineralogy is used in a study done on an Inco Metals Company nickel sulfide occurrence from 'the Thompson area in Northern Manitoba. The study included: a) determination of the variations in chemical composition of the ore minerals; b) determination of the liberation of the ore minerals for the various types of ore and for different feed grinds; c) assessment of the preliminary mill test results by comparing the mineral distribution in the different tailings. Preliminary mill test results had outlined three main problem areas: 1) unacceptabiy low grade concentrate with, 2) very high weight recovery and, 3) low pyrrhotite rejection resulting in a high sulfur concentrate. The mineralogical study readily explained these results by showing that: 1) between 20 and 40% of the nickel in the feeds and 55 and 75% of the nickel lost in the tailings is associated with pyrrhotite. This accounts in part for the low grade of the concentrates obtained at high recoveries: 2) hexagonal nonmagnetic pyrrhotite constitutes over 90 percent of pyrrhotite. Since hexagonal pyrrhotite floats more readily than monoclinic pyrrhotite, this could be part of the reason for the undesirable high pyrrhotite recoveries into the concentrates. Further test work to establish both the optimal grind and the best conditions for pyrrhotite rejection is therefore mandatory.

Jan 1, 1981

By Wei Luo, Yuanbo Zhang, Zhixiong You, Zijian Su, Guanghui Li, Tao Jiang

"In this study, the appropriate sintering process parameters for low-grade ferromanganese ores were investigated. The results showed that, under the condition of natural basicity (R=0.03), the optimal parameters were obtained as follows: moisture of mixture 9 .1 %, coke powder 9 .9% and sintering negative pressure 7 KPa. And the corresponding yield, ISO tumbling index and utilization coefficient reached at 80.18%, 61.27% and 1.515t·m-2·h-1, respectively. Under the optimal parameters, the emission of harmful gases, such as S02 and NOx, were reduced evidently with 30% of coke powder replaced by biomass charcoal. Moreover, it was found that the basicity had obvious effects on the quality of the sinters when it changed between 0.03 and 2.4. The ISO tumbling index gradually decreased from 61.27% to 55.47% with the basicity increasing from 0.03 to 1.2, then, it began to increase after the basicity further increased to 2.4.IntroductionManganese is mainly consumed by steel and battery industries, particularly in the steel plants and ferroalloy units. The consumption of metal manganese in the ferroalloy industry accounts for 85%-90% of the total Mn [1-2]. Therefore, ensuring sufficient manganese alloys is essential to meet the rapid development of steel industry. Recently, rich-manganese slag containing high grade Mn (>40%), low Fe (1%) and P (<0.03%) is considered as superior raw materials for manganese alloys. While the sinters made from manganese ores are major raw materials for producing rich-manganese slag with the increasing exhaustion of natural rich manganese lump ores [3-5]."

Jan 1, 2013

By Frederico Muylaert Margem, Jarbas Bravo Neto, Sergio Neves Monteiro

"The mechanical behavior and the fracture characteristics of composites with DGEBA/TETA epoxy matrix reinforced with up to 40% in volume of continuous and thinner ramie fibers were evaluated by tensile tests. Specimens with selected thin fibers aligned along the tensile axis were room temperature tested to rupture. The fracture surface was analyzed by scanning electron microscopy. The results showed significant increase in both the ultimate tensile strength and the elastic modulus. The fracture analysis indicated the possible mechanism for the fiber/matrix interaction, which could be responsible for the composite performance.IntroductionThe fiber reinforced polymer composite emerged in the middle of last century as a versatile engineering material for applications requiring mechanical resistance in association with lightness. Its most commonly used example is ""fiberglass'', i.e., a thermoset polymer matrix composite reinforced with glass fiber. Indeed, ""fiberglass"" has a specific strength of the order of 500 MPa.cm3/g, which is the double of the strongest steels like the maraging. This motivated, at earlier times, ""fiberglass"" to replace many conventional materials including wood and natural fiber composites. Today, ""fiberglass"" has a wide range of uses from aerospace systems and appliances to sport and leisure components. However, its fabrication as well as those of any synthetic fiber such as carbon and aramid composites, requires a relatively large amount of energy. Presently, a growing concern exists regarding the consequences to the environmental by gases like C02 associated with both the energy consumption and the processing of synthetic fibers and their composites. These gases are well known responsible for global warming [1]."

Jan 1, 2011

By Ze-Qiang Xie, Bai-hui Wang, Feng Chen, Ling-zhi Yang, Yu-feng Guo

In this paper, based on the big data in steelmaking process, equation about the relationship between steel composition (especially the oxygen content) and the element yield is established by using mathematical analysis method to analyze the factors influencing yield. Meanwhile, combining the alloy yield data-base that were established based on self-learning of historical data and computer technology in steelmaking process, a method of yield prediction of alloy elements is studied. To provide support for this method, alloying elements yield prediction software is developed to realize the rapid and intuitive site operation guidance, and to realize the precise control of dosage of alloy material.

Mar 1, 2017

By Omid Marzoughi

Chromium has a wide range of applications, including as an alloy addition in various steels and also as a corrosion resistance coating. Carbothermal reduction of chromite ore (FeCr2O4) in a submerged arc furnace is an important industrial process for extracting chromium, but the energy consumption is excessive. It is suggested that one area for future research is the low temperature carbothermic solid state reduction of chromite to produce an intermediate product, which can subsequently be upgraded to ferrochromium. In this regard, a thermodynamic model has been developed to investigate this process and the effects of temperature, carbon additions and ore composition on the recovery of chromium and the grade of the ferrochromium, have been studied. Further development of the model may allow it to be applied to the simulation of other processes for the recovery of chromium from chromite ores.

By Wilhelm Wendt

About five years ago we showed that it is possible to use the spectral in- formation in the light emitted by the off-gas flame of a PS converter for on-line production control. Very recently measurements have been performed using improved optical equipment and data evaluation software, resulting in both improved accuracy and the establishment of new optical process parameters. Using the optical signals the slag heats could be stopped at a predetermined Cu content of the white metal with an accuracy of +0.2% Cu m the range 74-78% Cu. A good correlation was found between the slag composition and optical data, providing a possibility for on-line monitoring of the SiO2 content of the slag. The measurements indicate the possibility of predicting the optimum end-point of the copper-making stage and having real time information on the impurity removal. Factors influencing the optical parameters, such as blowrate, Pb content, temperature etc. will be discussed.

Jan 1, 1993

By Jun Li, Lingling Zhang, Daqiang Cang, Guizhou Zhao

Pilot trial of direct modification of molten blast furnace slag and production of high acidity coefficient slag wool fibers were investigated nearby a blast furnace. Molten blast furnace slag discharged from blast furnace and then directly flow into specialized modification furnace and quartz was simultaneously added into the molten slag as modification agent. The modified molten slag was electric heated to 1500–1550 °C and then the melt was produced into slag wool fibers through high-speed centrifugation method. Melt with acidity coefficient of 1.2, 1.4, 1.6 and 1.8 were investigated and fibers with corresponding acidity coefficient were produced. Slag wool fibers with shot content of 5.5, 5.8, 6.2, 6.8% and average diameter of 4.5, 4.9, 5.6, 6.4 lm for four samples were successfully produced, respectively. Total energy consumption and production costs decreased by 50–70% compared to traditional cupola furnace method. This method provides an energy-saving and emission-reduction technology for the direct utilization of molten blast furnace slag.

Mar 1, 2018

By Dieter Neuschiitz, Pengfu Tan

"In order to understand the sintering phenomena during iron ore sintering process, a CFD model of iron ore sintering has been developed, combining with the kinetics of 15 relevant chemical reactions with the aim of describing the temperature fields and the gas flow patterns in the sintering bed. This CFD model can be used to simulate the concentrations of the gaseous and solid species, temperatures of the gas and solid, melting and molten fractions of the mixture, gas velocities, temperature zones and residence times of the gas in each temperature zone. IntroductionThe off-gas analyses clearly revealed that the off-gas of a sinter strand does not have a composition corresponding to thermodynamic equilibrium, for example, the CO, CO2 and O2 concentrations are not the mutually consistent equilibrium values. Apparently the chemical reactions in the sinter bed are controlled kinetically. Therefore kinetic modeling of sintering reactions combined with CFD modeling is necessary to understand the sintering phenomena during iron ore sintering process.Several models of iron ore sintering have been developed since 1970 [l-l 4l, each being more refined than its predecessor. The models were formulated as a series of differential equations to describe chemical and physical changes occurring at a point in the bed. These equations were solved numerically in a vertical plane along the strand. The present CFD model, based on the Nath's model [14], has been published in the reference [15]. In this work, some new chemical kinetic models of gas-solid reactions are incorporated in the present CFD model. The concentrations of gaseous and solid species, temperatures of gas and solid, melting and molten fractions of solid, velocity of gas, and residence time of gas in each combustion zone can be calculated by this model."

Jan 1, 2004