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By Masayuki Kudoh, Kiyotaka Matsuura

"Molten aluminum and nickel cast onto a steel block exothermically react and produce molten nickel monoaluminide, NiAI, which is simultaneously joined to the steel. The heat of the exothermic reaction is transferred to the steel block, and steel near the surface of the block is melted. The depth of the melted steel increases with both the initial temperature of the steel block and the thickness of the produced NiAI. Iron from the melted steel dissolves in the molten NiAI, and an intermetallic compound of NiAI-Fe pseudo-binary system is produced. During solidification of the intermetallic compound, it is strongly joined to the steel. The Ni.Al-Fe intermetallic compound has an excellent resistance to oxidation and corrosion.IntroductionAn intermetallic compound of nickel monoaluminide, NiAl, offers many advantages over conventional superalloys, such as higher melting temperature, lower density, greater specific modulus and higher thermal conductivity [1]. NiAl also exhibits excellent high-temperature oxidation resistance when doped with zirconium or hafnium, and excellent high-temperature corrosion resistance when doped with chromium or yttrium, that are superior to existing high temperature alloys or coating materials [1-4]. On the other hand, NiAI is significantly brittle at temperatures below 600 K [5-7], which is the most sigriificant disadvantage of NiAI. A possible way to overcome the disadvantage and to utilize NiAl as an environmental-resisting high-temperature structural material may be joining of NiAl to a ductile material."

Jan 1, 2000

By Pan Gu, Zhen Zhang, Jiang Diao, Bing Xie, Hongyi Li

Viscosities of FeO-SiO2-V2O3-CaO-P2O5 slags have been measured at the temperature range of 1673 K to 1773 K (1400°C to 1500°C). This investigated system represents the major components of basic vanadium slag that is an important intermediate product of a novel vanadium extracting process, in which removal of phosphorus and extraction of vanadium can be achieved from the vanadium-containing hot metal simultaneously. It was found that higher CaO/SiO2 ratio resulted in lower viscosity in the composition range of interest. Also, the viscosities increase with the increasing P2O5 concentration. The varying viscosities can be attributed to the modification in complexity and polymerization of the slag network. The variation of apparent activation energies are in tune with the viscosity measurements. The results of this work revealed the effect of CaO/SiO2 and P2O5 on the viscous properties of FeO-SiO2- V2O3-CaO-P2O5 slags and therefore provide the theoretical foundation for the control of the coupling de-P and V-extraction process.

Jan 1, 2016

By Fathi Habashi

Solid gas reactions of metallurgical importance can be classified into three groups: Physical processes, e.g., drying and sublimation Chemical processes which may be an addition or a thermal decomposition reaction Electrochemical processes which may be addition, oxidation-reduction, or displacement reactions. Examples are given and the role of the boundary layer is emphasized.

Jan 1, 1996

By Patrick R. Taylor

Iron phosphate glasses are promising host matrices for vitrifying actinide rich nuclear wastes materials because of their high solubility of actinide oxides, high chemical durability, and relatively low melting temperatures. An iron phosphate waste form was developed at the University of Missouri-Rolla. The structure and property of the waste form were well characterized by materials techniques. However, to scale the process and advance it to commercial viability, it is necessary to understand the processing parameters, such as the partitioning of waste elements and the viscosity as a function of temperature. Viscosity of 40 Fe203 - 60 P205 mole % iron phosphate melts (prepared with phosphorous pentoxide and ferric oxide) at 1000-1200 C was measured by the rotating-spindle method. It was discovered that this fluid has non-Newtonian behavior. Experiments were performed to study flow properties following the Standard Test methods for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield) Viscometer (ASTM D 2196-86). Samples prepared using ammonium phosphate and ferric oxide showed Newtonian behavior and the temperature dependence of the viscosity was studied over the range of 1000 to 1200 degrees C. The difference in flow behavior between the two fluids was analyzed in terms of preparation conditions and variation in the final composition and phases. The partitioning behavior of waste elements in the iron phosphate glass was studied by melting in a high temperature furnace and JCP analysis. The experimental results show that the solubility of Ce and Sr in phosphate glasses is significantly higher than the solubility associated with borosilicate glasses. This strengthens the conclusion that iron phosphate may be a viable alternative to borosilicate glass for immobilization of high heavy-metal-content wastes and actinide rich wastes.

Jan 1, 2002

By I. Gaballah

High and low grade concentrates of tantalum and niobium oxides were obtained by leaching a medium grade tin slag. Chlorination and carbochlorinalion of these concentrates were studied between 200 and 1000 "C. Chlorination or carbochlorination of the low grade concentrate led, at 1000 OC, to the extraction of about 95 % of the tantalum and niobium oxides. However, the tantalum and niobium chlorinated compounds were contaminated by iron and manganese chlorides. Complete extraction of the niobium and tantalum pentoxide was achieved during the carbochlorination of the high grade concentrate at 300 and 500 "C, respectively. While chlorination of this concentrate at 1000 "C, allowed to the volatilization of about 60 and 80 % of Ta205 and Nb205. In both cases, condensates were composed of almost pure tantalum and niobium chlorinated compounds. The results demonstrate the advantages of the lixivialion based on the "pseudo- structure" of the raw tin slag to obtain the high grade concentrate. The conclusions of this work suggest that the carbochlorination of the high grade concentrate is an efficient process for the extraction of refractory elements from tin slag.

Jan 1, 1993

By O. Ryosuke Suzuki

A new metallurgical process via sulfide is proposed: a sulfide is produced at a high temperature from its metallic oxide using gaseous CS2, and this sulfide is electrochemically reduced to its metallic state using molten salt. This combined process via sulfide is effective to obtain high purity of metallic powder, even if the metal in its oxide is strongly combined with oxygen. For example, it is not easy to reduce stable oxide TiO2, and only Ca can remove oxygen to form α-Ti. However, a fairly large amount of oxygen remains as Ti–O solid solution. Because the solubility of S in Ti is very small, this proposal was examined experimentally both on the conversion of TiO2 to TiS2 and on the successive reduction of TiS2 to Ti. TiO2 powder was exposed to CS2 gas flow at 1073 K, and the conversion to TiS2 was confirmed. TiS2 could be reduced to Ti powder either by calciothermic reduction or electrolysis in a CaCl2 melt. By Ca reduction at 1133 K in CaCl2 melt, sulfur concentration decreased to 0.03 mass%S when the amount greater than twice the stoichiometric calcium amount is added. By electrochemical reduction at 1173 K in CaCl2–CaS melt, S concentration significantly decreased to 0.01 mass% S when four times larger amount of electric charge was supplied.

By Jianhua Xin, Min Chen, Jin Xu, Hui Li, Nan Wang, Ming Chen

The kinetics study of blast furnace dust (BFD) recycling with flash reduction process at high temperature has been carried out using a high temperature drop tube furnace in laboratory scale. A combination characterization methods of chemical titration and SEM-EDS were used to track the reduction kinetics. The experiments using CO and CO2 mixtures with range of CO/CO2 (1:0, 1:1) at different temperature (1623–1723 K) and at different reduction time (1560– 2340 ms) were conducted. It was found that the reduction degree increases with the increase of temperature and reduction time as well as CO concentration. The carbon contained in the original BFD has weak in fluence on the reduction potential in the form of gasification. The unreacted core model was adopted based on the observation of the cross section and the measurement of iron element content, the effective diffusion coef ficient and reaction rate constant were determined and the rate controlling step was also analyzed.

Mar 1, 2018

By D. T. Smith, L. M. Hsiung, J. J. Schmitt, J. W. Golz, R. L. Lankey, H. N. G. Wadley, J. Z. Zhang, B. L. Halpern

"The microstructure and mechanical properties of Al/AI2O 3 metal-oxide nanolaminates fabricated by' a novel Jet Vapor Deposition (JVD) process at substrate temperatures of ~25° and -250°C have been investigated using transmission electron microscopy (TEM) and nanoindentation methods. The thickness of the oxide layer was held constant between 2 and 5 nm, whilst the Al layer thickness was systematically varied from -3 to -50 nm. Continuity of the Al layers was significantly improved when the nanolaminates were deposited at an elevated substrate temperature (-250°C). The yield strength of the nanolamintes with Al layers greater than -25 nm follows a Hall-Petch type relationship, whereas that of the nanolaminates with Al layers less than -25 nm is better predicted by a Koehler-Lehoczky strengthening model. IntroductionAluminum-aluminum oxide (presumably A12O3) nanolaminates have been recently fabricated using a novel Jet Vapor Deposition (ND) process developed and patented by Jet Process Corporation [1-4]. ND uses sonic, high purity helium (He) gas jets to entrain atomically dispersed vapor and deposit films. It is of interest here because it can deposit multilayered structures (laminates) inexpensively at high rates. Materials with a thin, multilayer structure are of interest because they potentially offer novel mechanical and physical properties [5]. Koehler in 1970 used an image force model to investigate the strength of laminated materials and proposed the use of alternating layers of high and low shear modulus metals to produce high strength composite materials [6]. He predicted that dislocations would have to overcome a large repulsive image force in order to move from metal layer B of lower shear modulus (uB) into metal layer A of higher shear modulus (uA)' The image force (F) is given by the relation:"

Jan 1, 1994

By Shujian Jia, Mingming Song, Gaoyang Song, Bo Song, Yuhou Yang

An innovative method is investigated to separate inclusion particles from liquid metal by super gravity. To make clear the characteristics of the inclusion separation, Al melt containing MgAl2O4 particles with diameters less than 150 μm has been treated under various super-gravity fields. The thickness of particle-accumulated layer formed at the bottom of the sample and the area fraction, number density and size of inclusions were measured. It is found that the thickness of the particle-accumulated layer decreases and the area fraction of particles at this location increases with the increase of super-gravity field. With the gravity coefficient G=500, time t=2 min, and temperature T=1023 K, it is hardly to find any solid particles in the upper and middle areas of the sample and the separation efficiency is up to 90%.

Jan 1, 2015

By Animesh Jha, Catherine Davey

"Carbothermic reduction and nitridation reactions using synthetic kaolinite mineral were investigated for the formation of silicon based nitrogen ceramics. The temperature dependence of the reaction rate and its effect on phases formed are reported. The effect of the reactivity of carbon on the kinetics of formation of AIN and ShN4 is discussed. Using the standard Gibbs free energy values for the formation of nitrides and oxides of aluminium and silicon, a log po2 verses I/T diagram is constructed. The experimental data results are discussed and compared with the predicted phase equilibria. We also report the influence of sub-oxide gaseous species on the microstructure of the ceramic phases produced.IntroductionSynthetic kaolinite is a clay containing alumina, silica and water of crystallisation, and has a chemical formula 3(Al2O 3.2SiO2.2H2O). This mineral is relatively inexpensive and, is therefore an ideal candidate for use in the production of ceramic powder mixtures for example silicon nitride and aluminium nitride for composite material formation, When the mineral is heated, the water of crystallisation from the crystal lattice is lost via the 3(Al2O 3.2SiO2.2H2O) = 3(Al2O3.2SiO2) + 6H2O reaction. It has been shown [1·2j that on further heating to 1673K, the anhydrous kaolinite decomposes to a mixture of mulllte and silica, 3(Al2O3.2SiO2) = 3Al2O 3.2SiO2 + 4SiO2 which is consistent with the alumina-silica phase diagram, shown in figure 1.The binary alumina-silica phase diagram has a well-defined sub-eutectic immiscibility dome and this characteristic dernixing behaviour is reflected in the thermal decomposition of anhydrous kaolinite consequently the microstructural features resemble the spinodal decomposition process. It is well established that the spinodal decomposition process raises the nucleation frequency due to their low free energy barrier, (?G). The small magnitude of this barrier consequently promotes the evolution of a very fine microstructure. The process of spinodal decomposition is therefore expected to be influential during the reduction-nitridation of kaolinite minerals."

Jan 1, 1996

By Frank Mucciardi, Hujun Zhao, Pietro Navarra

"A heat pipe is a device having a very high effective thermal conductivity in which two-phase flow and heat transfer takes place. Recent research at McGill University has led to a new type of heat pipe that contains a flow modifier. This improvement has enabled the device to operate at the high heat fluxes encountered in the metallurgical industry.This paper summarizes the progress made to describe the fluid flow in the evaporator section of a McGill heat pipe with the goal of understanding how the flow modifier configuration is linked to the film boiling and dry-out limitations. A separated flow model, an instability analysis, a lift-off model and an energy balance model are used to calculate the theoretical CHF with varying flow modifier configurations and operation conditions. A summary of the current work to relate the flow modifier to the dry-out limitation is also given.Determining how the flow modifier affects both the film boiling and dry-out limitation will give insight into improving the flow modifier design so as to extend the operational range of McGill heat pipes in terms of maximum heat flux and heat load capabilities.IntroductionThe McGill heat pipe is a specialized two-phase heat exchanger developed for several metallurgical applications where temperatures and heat fluxes are typically close to or beyond the maximum safe range of conventional cooling technology.Over the last few years, several breakthroughs have brought this device beyond the proof-of concept stage and a series of industrial trials have been performed with success. These trials include two oxygen injection applications for the ferrous and non-ferrous industry [l], and two light metals permanent-mould casting applications [2,3]. Current projects include a blast furnace copper taphole cooling application [4], a copper smelting application and a thermal analysis probe application."

Jan 1, 2004

By Dietmar Eifler, Benjamin Jost, Marcus Klein

This paper focuses on the ductile cast iron EN-GJS-600 which is often used for components of combustion engines. Under service conditions, those components are mechanically loaded at different temperatures. Therefore, this investigation targets at the fatigue behavior of EN-GJS-600 at ambient and elevated temperatures. Light and scanning electron microscopic investigations were done to characterize the sphericity of the graphite as well as the ferrite, pearlite and graphite fraction. At elevated temperatures, the consideration of dynamic strain ageing effects is of major importance. In total strain increase, temperature increase and constant total strain amplitude tests, the plastic strain amplitude, the stress amplitude, the change in temperature and the change in electrical resistance were measured. The measured values depend on plastic deformation processes in the bulk of the specimens and at the interfaces between matrix and graphite. The fatigue behavior of EN-GJS-600 is dominated by cyclic hardening processes. The physically based fatigue life calculation “PHYBALSIT” (SIT = strain increase test) was developed for total strain controlled fatigue tests. Only one temperature increase test is necessary to determine the temperature interval of pronounced dynamic strain ageing effects

Jan 1, 2015

By Alex Meystel, Diran Apelian

"In this paper, an outline is given for a theory of intelligent control (IC) of manufacturing processes (MP) based upon what all of them have in common: all MP's can be represented as distributed networks of sequential/parallel elementary ""lumped"" models; all elementary models are organized by definite input-output conditions, and by the set of constraints; all elementary models incorporate not only well defined physical knowledge, but also assumed physical knowledge, expert knowledge, expected knowledge to be obtained during the process from sensors, etc. This creates a hierarchy of elementary controllers coordinated by local coordinators of different levels up to a global coordinator. The latter verifies the adequacy of MP by using a holistic image of the process: depictogram. The structure of knowledge based controller is introduced, and the analytical/linguistic tools of control are presented. The concept entails a number of perspectives which are discussed in the conclusions.1. IntroductionIt is becoming increasingly clear to those of us in Engineering and Technology oriented fields that the so called ""service industries"" do not create wealth. Moreover, it is now accepted that manufacturing is the key to the creation of wealth from a socio-economic point of view. This appreciation of the importance of manufacturing is reflected by the transformations we are seeing in our factories, as well as the changes in both curricula and research activities of our universities. Though we find these changes to be in the right direction, there is yet much more to be done to advance the frontiers of manufacturing and materials processing as we approach the third rnillenium."

Jan 1, 1988

By J. Boltano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Codelco-Chile. A discussion on design conditions for a future Sulphuric Acid Plant using Teniente Converter gases is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited gas handling capacity for operation under future process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente Converters Installed in 1987-1989 improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By Donald J. Hallbom

Limonitic nickel laterites slurries exhibit complex rheological properties including time dependency that varies from thixotropy to rheopexy. Chronic problems may occur if plant designers and operators fail to take time dependency into account. Stress decay tests indicate that laterite slurry takes roughly two minutes to approach steady state after a step change in the shear rate. As a result, most rheometer measurements are taken at a non-equilibrium state, making evaluation difficult. Two minutes is also long relative to the time that a unit of slurry in a processing plant is at any given shear state, so the slurry may never reach equilibrium. This paper presents a method to describe the rheology of laterite slurry using a Flow Array, which describes the rheology using an array of instantaneous flow curves crossed by an equilibrium flow curve. A rate equation for structural change in non-equilibrium conditions allows time dependence to be efficiently modeled. This flow array allows the flow behavior of time- dependent slurry to be predicted in non-equilibrium conditions using a simple time-step methodology. Keywords: Rheology. nickel laterite, hydraulic transport, pressure acid leach, flow array

Jan 1, 2004

By Ronald L. Pariani

To date, significant advances have been made regarding the development and commercial implementation of full deposit stripping in the copper industry such as practiced at Copper Refineries, LTD in Townsville, Australia. The paper describes the history and current practice of Electrowinning (EW) plants which may be coupled with solvent extraction. The modular nature and degree of automation are described in relation to the various sizes of operations. Reference is made to the expansion capability of commercial equipment plus associated economics of the mechanical processes for producing full cathode deposits. It is recognized that the technology described may be adaptable to other nonferrous refining areas where feasible. The paper highlights the state of the art in mechanized stripping equipment as applied to current and planned SX-EW plants.

Jan 1, 1987

By Richard Elliott

Current methods for producing low-carbon manganese alloying materials for the steel industry are energy intensive and costly. To enable wider implementation of high Mn steel alloys, a novel solid-state Mn ore reduction strategy is therefore being investigated. This solid-state process, modelled on existing Direct Reduced Iron technology, employs a methane-containing atmosphere to reduce Mn ore pellets to a metal carbide. These pellets may then be smelted, yielding a Mn-rich master alloy. It is well established that CH4 is a suitable reductant for Mn ore powders; however, the reduction behaviour of industrially relevant Mn ore pellets by CH4 is poorly understood. The present work reports the results of an investigation undertaken to address this knowledge gap. The results of this study highlight the significantly different reduction behaviour exhibited by the Mn ore pellets relative to the ore powder under similar conditions and suggest that the diffusion of CH4 into the pellet interior is the limiting factor in achieving complete reduction.

By N. A. Vatolin, L. I. Leontjev, S. V. Shavrin

The ever growing interest to the complex iron ores may be attributed to possible production of the naturally alloyed metals and the efficient recovery of the associated elements. However, the conventional technique for complex ore processing is complicated and in some cases even impossible. A pyrometallurgical benefiation of such ores without melted slag formation has been advanced. A version of the technique assumes pellet production with metal coagulated within a slag shell on grinding the pellets, the metal phase is mechanically separated from the slag shell. The technique has been run up with ferro chromo nickel, high-titanium, high-magnesia, alumina phosphorus ores and concentrates. Another version of the pyrometallurgical benefication without melted slag formation in a rotary kiln has been developed from the schemes for processing red mud of alumina manufacture and high-titanium concentrates. Means have been put up to improve schemes available for lex iron ore processing with primary emphasis on material pretreatment before blast furnace and steelmaking processes. Vanadium-bearing titanomagnetite conentrate oxidized pellets possess low strength at reduction. The technique suggested for pelletizing in the controlled atmosphere improves the afore said pellet metallurgical properties. Prodution of metallized pellets in a conveyor roasting machine holds considerable promise for blast furnace and steelmaking processes. In processing the high-sulphur iron ores still another technique is proposed to roast the fluxed pellets with 95% and more desulphuration.

Jan 1, 1988

By K. Itagaki, H. Henao

"The experimental study on the phase equilibrium and distribution of minor elements such as chromium and copper between magnesia saturated FeOx-MgO-SiO2 slag and Fe-Ni alloy were carried out under controlled oxygen partial pressure between 10-6-5 and 10-10 using CO and CO2 mixed gas at 1773 and 1873 K.The effect of slag additives such as lime (CaO/SiO2 molar ratio: 1) and alumina (AlO1.5/SiO2 molar ratio: 0.1) on the distribution behavior of the minor elements was also investigated.The value of distribution ratio for chromium, defined by (%Cr in slag)/[%Cr in alloy], is larger than 70 at the pO2 region conducted in the present study for the MgO saturated FeOx-MgO-SiO2 slag at 1773K. These value are almost 4-order higher then that of nickel though the distribution ratio of copper shows similar values with nickel. Analysis of the data indicates that addition of lime in the slag and the increase of temperature reduce the dissolution of chromium into the slag and the addition of aluminum increases the dissolution of chromium into the slag while reduces the dissolution of copper and nickel.IntroductionChromium. is a minor element in a nickel oxide ore but a Japan major component in the secondary material of stainless steel and is also introduced in the Fe-Ni production process due to dissolving bricks of a furnace. Chromium is a concerned matter for the beneficial utilization and disposition of ·slag because Cr6+ is a harmful element. Considering Fe-Ni as an alloy component in steel making, and the demand of high purity nickel, chromium is an -undesirable element that has to be eliminated into slag prior to the steel making, or the production of high temperature refractory alloys. On · the other ·hand chromium is an element of steel alloy for many applications, thus Fe-Ni containing chromium in minor element is desirable in some stainless steel making."

Jan 1, 2000

By H. Hirayama, T. Okura, O. Kato

"Saganoseki Smelter & Refinery, one of the largest copper smelters in the world, has the annual capacity of 300,000 metric tons in copper content with two flash furnaces, six Pierce-Smith type converters, two anode furnaces, four acid plants, three tank houses and perfect pollution control system.Coping with the many severe conditions surrounding the copper industry in the last decade, Saganoseki Smelter has kept performing the stable operation, while enhancing the smelting capacity and developing new technologies such as the hydrometallurgical treating of converter dust recovered at electric precipitators. Especially in the operation of flash furnaces, which are of Nippon Mining's conversion type using hot air in a temperature of l,000ºC some technological improvements and complete operation control factors have approved the concentrate feed rate to reach to 2,200 tons a day for a flash furnace.Reported in this paper are the production control design for copper smelting process, and the operation control scheme of the flash furnace following the brief review of the characteristic of Saganoseki Smelter's process and some improvements. Copper Smelting ProcessDescriptions of major unit operations and general specifications of the copper smelting facilities are summarized in Table 1, and the present flowsheet of the copper smelting is described in Figure 1 (1,2).Outputs and raw materials treated in the last five years are shown in Table 2, in which concentrate includes powder copper scrap which amounts to 3 to 4% of concentrate.A full operation was performed for a period of one month, for both one flash furnace operation and for two flash furnace operation. With one furnace operation, 19,200 tons of copper were produced. With the two furnace operation, 84,000 tons of concentrates were charged and 33,500 tons of anode (net 28,600 tons of copper) were produced.The actual production level, however, has been kept at 80 to 90% of the full capacity because of low copper price, tight market of copper concentrate or fall of net demand in Japan."

Jan 1, 1989