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By Gerson de Araújo Filho

This paper shows the use of tires as fuel to be employed into blast furnaces. The tires can substitute coal or even charcoal in the blast furnaces tuyeres. The injection into tuyeres, besides the contribution for energy generation, can also produce gas for iron oxide reduction. The tires, as powder to be injected into blast furnaces, contributes for an environmental use of this waste, which helps to obtain a high value product as well. So, the advantage of using such material is that it is waste and has lower cost for preparation. The obtained results showed that the tires have good combustibility. This one was obtained in a model that simulates the same conditions occurring in the blast furnaces tuyeres; these used raw materiais include tires and mixtures of tires with coal or even with charcoal.

Jan 1, 2006

By F. T. Principe

In order for solvent extraction technology to be acceptable as an alternative to existing jarosite precipitation circuits, iron must be cleanly separated and concentrated into a feed stream suitable for downstream iron by-product recovery which meets market specifications and economics. Ten years ago, significant progress was made in a joint McCill University/CANMET project that involved iron extraction with mono(2-ethylhexyl) phosphoric acid and stripping with HCI. Our iron solvent extraction research was reactivated recently by looking into this and other members of the organophosphorus extractant family. Our research focuses on the mechanisms and control of anion (SO42/CI) transport across the various phases (Rafinate/Organic/Strip), iron build-up in the strip liquor, and extractant stability/selectivity. In this paper, these issues along with some other performance parameters are discussed using data derived from an extensive search of the two commercially available and best known members of the organophosphorus family, di-2-ethylhexyl (D2EHPA) and mono-2-ethylhexyl (M2EHPA) phosphoric acid. Further in this discussion, the challenges lying ahead in the development of sx systems that overcome the deficiencies of D2EHPA and M2EHPA are outlined. In particular, the necessity of considering secondary separation technologies that can further concentrate iron values in the chloride strip liquor to levels economically attractive for the production of saleable iron oxide by pyrohydrolysis is addressed.

Jan 1, 1998

By Xiang (Frank) Chen, Mikhail A. Sokolov, Randy K. Nanstad

"Nickel-base Alloy 617 is being considered as a structural material for application in the secondary heat exchanger of the New Generation Nuclear Plant, a very high temperature gascooled reactor. Thermal aging of Alloy 617 plate and welds is being performed with tensile, Charpy impact, and fracture toughness tests conducted at temperatures to 950°C. Results of testing for thermal aging to 5,300 h have been obtained and are presented; varying effects of thermal aging temperature and time on fracture toughness are observed. The 9Cr-1MoV (Grade 91) ferritic steel is a candidate for structural applications in the sodium fast reactor. Fracture toughness testing of unaged Grade 91 steel has been performed to evaluate specimen size effects in preparation for future testing of the material in the thermally aged condition. Results for material in the mill-annealed and heat treated conditions are presented and show that this heat of Grade 91 steel does not indicate a small specimen bias on the fracture toughness Master Curve reference temperature.IntroductionThe behavior of advanced engineering materials will be a critical factor in the performance of Generation IV reactors. In the case of materials utilized for reactor internals and pressure vessels, the effects of irradiation and long time thermal aging are major issues. The environmental conditions for some of the Gen IV reactors are generally beyond present day reactor technology, requiring new experimental data as well as analytical predictions of expected behavior of candidate materials at conditions for which there are only sparse or no experimental data. The radiation environments and several key materials issues for some Gen IV systems are summarized in Section 5 of [l] as a starting point for modeling and microstructural analysis of Generation IV materials. More detailed descriptions of materials research and development needs and recommended activities for the SCWR, VHTR, and GFR are provided in references [2, 3, 4], respectively. Mansur, et. al. provide an interesting comparison of materials needs for Generation IV reactors to corresponding needs for fusion reactors and spallation neutron sources in [5]. The two primary candidate reactor systems currently undergoing significant research and development by the U.S. Department of Energy (DOE) are the New Generation Nuclear Plant"

Jan 1, 2012

By J. W. Ahlrichs

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.

Jan 1, 1981

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. In this work, thc potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (DW). Seven taxa are of Alyssum genus and one of Bornmuellera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mglkg or 2.5%) and Alyssum markgrafli O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By Donald R. Fosnacht

An investigation was initiated to obtain the scope of the problems associated with recycling various waste oxide materials generated at Inland Steel and to identify and? test techniques that could possibly aid in increasing the amount of waste oxide materials recycled to primary. operations. Based on the results of this work, several new techniques were developed ?and tested on ?a plant or laboratory scale. These include the use of cold-bond agglomeration methods for producing waste oxide agglomerates for use as a cooling agent or scrap substitute in steelmaking operations, and the use of various techniques for beneficiating blast furnace flue dust and soaking pit rubble so that the upgraded materials can be utilized in sinter plant or ironmaking operations. The physical and chemical characteristics of the waste oxide materials and the results of the laboratory and plant testing are discussed in this paper.

Jan 1, 1985

By Zuhair A. Munir

"The use of self-propagating combustion reactions to synthesize metallic, ceramic, and composite materials is described. The limitation of this process because of the porous nature of its products is discussed. The formation of dense bodies through the simultaneous application of pressure is shown for a metal-matrix composite. The effect of an external electric field on the synthesis of ceramic and composites is described. The nature of the effect of the field on the mechanism of synthesis is analyzed theoretically and experimentally. The use of the self-propagating combustion to synthesize intermetallic thin films is presented for the Ni-Al and Ti-Al cases. The formation of functionally gradient materials (FGM) by centrifugally-assisted self-propagating high-temperature synthesis is described.IntroductionThe use of self-propagating combustion reactions for the synthesis of a large number of simple and complex materials has been described in numerous publications. These have been amply discussed in several review articles [1-4]. The many benefits of this method of materials synthesis are commonly examined in light of its most significant limitation: the porous nature of its products. The porosity in the products of self-propagating high-temperature synthesis (SHS) is an intrinsic characteristic of the process and its elimination has been the focus of numerous attempts. Various experimental methods have been used to accomplish this goal."

Jan 1, 1994

By Luciano B. Oliveira, Luis G. C. Marques, Sergio N. Monteiro, Marcos V. M. Fagundes

"Biodiesel production is normally associated with large plantations of oily vegetables such as soybean and colza, in large rural areas. However, in the municipal limits of the city of Rio de Janeiro, southeast of Brazil, biodiesel is being produced from wastes commonly generated by typical urban activities such as sewage sludge, discarded fat from meat markets and post-used cooking oils. In the present work, the experience of producing biodiesel from urban wastes in Rio de Janeiro is assessed. The type of precursor materials, equipments and logistics are presented. The environmental and economical advantages as well as the drawbacks are discussed.IntroductionThe interest for a liquid fuel that could substitute those obtained from petroleum started more than one hundred years ago when Rudolph Diesel tested his no-spark internal combustion engine, impelled by compression, with peanut oil. By that time, petroleum was beginning to be extracted in large scale and no one was concerned with the future environmental problems and its eventual depletion. In the last century, the successful association of petroleum based fuels with the automotive industry was an almost insurmountable obstacle to any attempt to use nonmineral oils [1]. In addition to the greater efficiency and, by then, lower price of the diesel from petroleum, the use of plain vegetable oils introduced undesirable carbon deposits and reduced the engine lifetime. Today, the situation is reverse. The continuous increase in the price of petroleum and, above all, its contribution to climate changes are strongly motivating the use of biofuels to replace those obtained from fossil fuels such as petroleum, natural gas and coal [2].In the case of the common petroleum derived diesel, many countries are now engaged in large scale substitution programs. The USA should produce more than 700 million litters of biodiesel, while the European Community is expected too produce around 6.5 billion litters in 2008. In Brazil, the federal biodiesel program imposed a minimum of 2% addition to the common diesel. This would demand a production of 800 million litters in 2008 [3]. The Brazilian biodiesel is made from a diversified source of vegetables mainly castor bean, African palm and soybean. The main producers are agrobusiness firms located in large rural areas of the Brazilian hinterland [4]."

Jan 1, 2008

By K. Suseelan Nair

Magnesium alloys containing rare earths are finding increasing applications in space programmes. A number of alloys have been developed and e good data base an the mechanical properties of these alloys is available. However details on metallurgical aspects are found to be sparse in, literature. This paper, at first, briefly reviews the available data on these alloys and subsequently presents the microstructural investigations conducted on quatenary fig-4.9% Zn-1% Rare earth-0.5% Zr cast alley, using optical metallic-graphy, electron probe micro-analysis and X-ray diffraction techniques.

Jan 1, 1989

By Chengyi Ding, Xuewei Lv, Changyang Ji, Rende Zhang, Xiangwei Zheng

Inexpensive and high-quality sinter has an extraordinary position in iron making, and there are many factors influencing the sintering. This research takes the basicity and coal dosage as research subjects to do the experiments based on cost analysis with sinter pot experiment system. Linear program is taken to make the schemes of ore blending. During the experiments of changing basicity from 1.6 to 2.3, the properties and microstructures of the sinter are studied. It comes to a conclusion that increasing the basicity is beneficial to sinter quality but leads to higher cost. To further ascertain the cost of sinter and the potential of saving coke, the work of improving coal dosage is taken on the basis of experiments of changing basicity. Through analyzing the results, a formula (Y=1849+261.1R-130.6C) is proposed which indicates the relation among the cost, basicity and fixed carbon content. And it works well for actual production.

Jan 1, 2015

By Matthew John M. Krane

"The macrosegregation patterns and convective behavior of a Pb-5wt%Sb-35wt%Sn alloy are studied using new numerical treatments of solid particle motion and of transport phenomena occurring during the solidification of ternary metal systems. At this composition, the solidification which occurs while the local liquid composition is in the (Pb)-(SbSn) binary eutectic trough has a significant effect on these phenomena. The effects of this solidification path on fluid flow and macrosegregation are compared to the more familiar binary alloy patterns and the effect of solid particle transport is evaluated. The final predictions of macrosegregation are compared to measured composition profiles. IntroductionThe macroscopic maldistribution of alloy constituents during solidification, commonly called macrosegregation, is a defect which occurs in real metal processing systems. This nonuniformity of species distribution, especially when it forms a high composition gradient or a poor distribution of secondary phases, can lead to areas of high stress concentration, which contribute to cracking during extrusion or forging of wrought alloys or when an as-cast piece is severely loaded in service [1, 2]. Macrosegregation studies in binary systems have become quite common since the introduction of single-domain numerical models which feature one set of conservation equations and boundary conditions for an entire, fixed computational domain containing solid, liquid and multiphase regions. A complete review up to 1995 has been presented by Prescott and Incropera [3]. However, most commercial alloys generally have more than two species in amounts significant enough to affect the convective flows which lead to macrosegregation and other defects. The formation of secondary solid phases, including eutectic and peritectic reactions, also may occur in commercial metal alloys and should be treated using appropriate thermodynamic models."

Jan 1, 1999

By Pekka Taskinen

The converter-less nickel matte smelting technology (DON) adopted more than 20 years ago in Boliden Harjavalta smelter has been since that applied successfully to the processing of large number of nickel sulphide concentrates of various Ni-to-Cu ratios and MgO contents. The operational point of the technology is far from the conventional primary nickel smelting in the smelting-converting route. Therefore, a careful scouting of distribution equilibria of the base and trace elements in the smelting conditions of DON process has been conducted, in order to obtain quantitative information about the equilibria and thermodynamic properties of the nickel mattes at low iron concentrations, less than 10 wt% [Fe] in matte. The series of investigations has included novel experimental and analytical techniques for increasing the reliability and sensitivity of the phase equilibria as well as the element distribution observations carried out in typical high-grade nickel matte smelting conditions.

By Suchun Zhang

The alkaline oxidation of refractory gold concentrates containing arsenopyrite and pyrite at ambient temperatures and pressures has been found to be accompanied by the simultaneous dissolution of gold without the addition of cyanide. A detailed study has been made of the kinetics of the oxidation of the pure minerals and of several concentrates. The reaction products of the oxidation of arsenic and sulphur have been monitored using chromatographic techniques. In the case of arsenopyrite, thiosulfate, monothioarsenate, arsenate and sulfite are the principal products while thiosulfate has been confirmed to be the dominant product of pyrite oxidation. Gold, either as added powder or as a constituent of the concentrates has been found to dissolve simultaneously during the alkaline oxidation of both arsenopyrite and pyrite, and this appears to be associated with the in-situ formation of thiosulfate as a lixiviant. The effects of temperature, stirring speed, oxygen partial pressure, alkalinity and pulp density on the oxidation of arsenopyrite and the dissolution of gold have also been investigated. Keywords: Gold, dissolution, arsenopyrite, pyrite, alkaline, oxidation, thiosulfate, thioarsenate

Jan 1, 2005

By Baozhong Zhao

The direct smelting of copper concentrates to copper metal in a single furnace offers environmental and energy advantages over conventional two-stage copper smelting processes. However, the direct copper making results in unacceptably high level impurities (As, Sb and Bi) in the anode copper. Experimental studies have shown that it is possible to remove these impurities from molten copper by injection of sulfur-hexafluoride. This paper discusses the experimental findings on the influence of various factors on the rate of removal of impurities, such as the impurity inter-effects, initial oxygen content in the metal and injection rate of SF6.

Jan 1, 1995

By J. W. Perez

A simple exponential model has been developed (Perez and Aplan. Process Mineralogy, VI, 1986) to describe the fractional yield of a given species out of a locked assemblage: Fractional Yield of Species A = a e X/U where 'X' is particle size and 'a' and 'U' are constants. In the present study, the general validity of this model has been further demonstrated. experimentally, for the liberation of coal and pyrite out of various raw coals and beneficiated fractions using a variety of crushing devices. Using data from the literature, the model is also shown to be applicable to the liberation of sulfide minerals out of ores.

Jan 1, 1987

By Toshio Suzuki, Machiko Ode, Won Tae Kim, Seong Gyoon Kim

"The Ostwald ripening and growth and coarsening of the secondary dendrite arm are studied using a phase-field model. The phase-field parameters are obtained at a thin interface limit proposed by Kim et al. In Ostwald ripening analysis, the difference of the concentration due ·to· the curvature effect is shown. The third power of the average particle radius Rav is proportional to time and the ripening constant shows a good agreement with the value by Deppers et al. The particle radii distribution shows the transition behavior to attain a self-similar stationary shape. The growth and coarsening behavior of the secondary dendrite arm is also analyzed using a phase-field model. The estimated arm spacing and its dependence on time are in good agreements with experimental data.IntroductionThe ripening or coarsening process controls the microstructure during the late stage of solidification. The ripening phenomena are recognized firstly by the Ostwald [1]. The first quantitative analysis for the Ostwald ripening in the limit of vanishing solid fraction was provided by Lifshitz, Slyozov and Wagner (LSW) [2,3]. In their study, that the mean radius grows proportional to the cubic root of time and the size distribution of precipitations shows a ""self-similar"" shape are shown. Most of the studies for the Ostwald ripening confirm or predict these two general rules above. In case of finite solid fraction, the general rules are observed but the ripening constant is larger and the self-similar shape is wider than the LSW prediction respectively [4-6]. To analyze· the high solid fraction system, the theories that consider the solute field correlation are proposed [4,7-8]. In the theory, however, since the particle is treated as the point, the effect of the concentration field deviation from the monopole field should be taken into account. Recently the numerical simulation, in which not only diffusive transportation of solute but also convection effect is considered, has been done using a phase-field model [9]."

Jan 1, 2000

By P. N. Anyalebechi

"The as-cast microstructure of two commercial-size ingots of aluminum alloy 3004 produced by the electromagnetic casting process was quantitatively characterized. This involved the quantitative determination of through-thickness and across-width variations in dendrite cell size, grain size, macrosegregation of alloying elements, interparticle spacing, and the types, volume fractions, and sizes of the constituent or second phase particles. More than ninety-five percent of the constituent phases in the ingots consisted of the A16(Mn,Fe) phase; the desirable a-Al 12(Fe,Mn)3Si phase was not detected in any of the ingots by Guinier X-ray diffraction analyses or electron probe X-ray microanalyses. A significant microstructural heterogeneity through the thickness and across the width of both ingots was observed. For example, macrosegregation, and the sizes of the constituent phase particles, dendrite cells, and grains increased concomitantly from edge to mid-width and from surface to center of the ingots. There was a -20% depletion (negative macrosegregation) of Mg and a +54-87% enrichment (positive macrosegregation) of Ti in the center of the ingots. With the exception of grain size, there was no significant microstructural difference between the two ingots examined. The causes and practical implications of the observed microstructural heterogeneity in the ingots are discussed.IntroductionThe first step in the fabrication of majority of wrought products of aluminum and its alloys is the casting of large ingots or billets of simple shapes (round or rectangular). The sizes of the ingots vary from 10 mm to 450 mm diameter or 25 mm to 780 mm thick. The quality of the finished products is established at the ingot casting stage. This is because the microstructural characteristics, such as secondary dendrite cell size or arm spacing, amount of alloying elements retained in solid solution, macrosegregation, and the characteristics of second phases, produced during casting cannot be reversed by subsequent processing. Up until twenty-five years ago, the effect of as-cast microstructure of large ingots on the structure and behavior of thin sheets (0.34 mm thick) during drawing and ironing processes was incorrectly assumed to be minimal or nonexistent. This was based on the erroneous notion that the thermal treatments and large reduction (>99.94%) and strain that the ingot undergoes during production of the sheets completely destroys the original ingot structure and its inherent heterogeneity. However, the effects of ingot structure can, a priori, be deduced from the observed effects of constituent phase particle size, type and volume fraction on recrystallization, development of texture during annealing and deformation, and earing. In fact, careful examination of the behavior of products produced from different size ingots or castings have shown that the original microstructure of the ingot has a direct impact on the properties and performance of the end products."

Jan 1, 2011

By P. Lussiez

Precipitates consisting of amorphous ferrihydrite and crystalline goethite have been prepared by aging hydrolyzed Fe (III) solutions at room temperature. The precipitates have been characterized by x-ray diffraction and differential thermal analysis. The amorphous ferrihydrite transforms to goethite with time. The ferrihydrite to goethite transformation is affected by the presence of small amounts of copper or nickel coprecipitated with the iron. .The addition of copper decreases the amount of goethite at a given aging time and increases the amount of coprecipitate which is initially dissolved in sulfuric acid, but it does not seem to affect the dissolution of the crystalline part'. It is proposed that adsorption of copper hydroxo species on goethite nuclei delays the ferrihydrite to goethite transformation. The effect of nickel is less dramatic than that of copper. Apparently a portion of the added nickel is adsorbed on the goethite crystallite surface rather than incorporated into the goethite lattice.

Jan 1, 1981

By Xie Zhang, Jiang Diao, Xiaojun Li, Bing Xie

"Vanadium is widely utilized as an important element to improve the quality of alloyed steels in iron and steel industry. Moreover, the crystallization process of V-containing spinels plays a significant role due to the aim of achieving a fairly larger size of spinel crystals in vanadium extraction. Thus, a comprehensive exploration and discussion on the competitive precipitation and growth of vanadium, chromium and titanium spinel crystals in vanadium slag during a cooling process were carried out in the present study on the basis of a crystallization kinetic model. To be more specific, the abilities of forming crystal, precipitation order and suitable temperature range for crystallization of the three kinds of spinels were discussed with both theoretical and experimental methods.IntroductionVanadium is an important element which is used almost exclusively in ferrous and non-ferrous alloys due to its excellent physical properties such as high tensile strength, hardness, and fatigue resistance [1]. Various kinds of processes of vanadium extraction from V-containing hot metal are available at present. However, only four processes which are the Highveld process (South Africa), the Pan-steel process (China), the NTMK duplex process (Russia) and the New Zealand steel process (New Zealand) take the dominant positions [2, 3]. Although the type of reactor and the initial vanadium content in hot metal are different in these techniques, they share the same principle that vanadium is oxidized by oxygen into vanadium slag."

Jan 1, 2012

By K. Robinson

Following the longest Smelter campaign in BCL?s history it was planned to completely rebuild the flash smelting furnace in 1987. This was the fourth major overhaul and the most extensive so far attempted. Detailed planning took place over several year$ preceding the shutdown and implementation was completed in 54 days. The key to minimising shutdown time was the method designed for installation of the new uptake shaft and reaction shaft. Major repair work was also undertaken in the waste heat boiler and electric furnaces. Both of these activities had an impact on the critical path of the flash smelting furnace overhaul.

Jan 1, 1993