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By Xuewei Lv

An intelligent recognition and quantification system for the micrographs iron ore sinter was developed in the current paper. The average distribution parameters in a gray histogram of minerals by a Gaussian gray distribution model were obtained. The feature curves of the gray histogram of two minerals were achieved by combining the two density functions. The feature indexes, such as the number and position of the peaks and the valleys of two minerals in different ratios, were quantified by differentiating the distribution functions. This algorithm is able to extract the feature of the minerals adequately and accurately for recognizing the composition and phases of the minerals intelligently.

Jan 1, 2009

By K. Yarnaguchi

In the Mitsubishi Continuous Copper Converting Furnace, calcium femte slag is used. Due to its extremely high basicity, the improvement of corrosion resistance of the refractory lining is in need. In order to clarify the corrosion mechanism and to search for a new corrosion resistant material, first, the surface snuctures of bricks corroded in molten slags were observed by EPMA. Second, the dissolution behaviors of sintered MgO-based pellets containing various oxide additives were examined. It was found that the formation and the dissolution of magnesiofemte at the surface of the bricks play an important role in their corrosion and an addition of NiO, Mn02, or Ti02 to MgO is effective in stabilizing the magnesio-femte and improving the corrosion resistance of MgO.

Jan 1, 1994

By Preben Ingerslev

Control of the reheating of ingots is based either on surface temperature measurements using optical pyrometers or on furnace set points and reheat time determined empirically. This paper presents a real-time mathematical heat flow model, named BESTT, which calculates the temperature distribution in an ingot cross section when reheated or cooled. The model runs on a 486 PC in less than one minute for a variety of ingot cross sectional shapes such as circular, square and with some considerations octagonal and heavy-cornered square. Initial temperatures can either be uniform or nonuniform while accounting for temperature dependent thermophysical properties. The model was developed and verified using 718 alloy ingots in box type furnaces. When integrated with on-line pyrometric measurements, BESTT can provide for improved feed back in the reheating control loop. The use of BESlT will assist in reducing energy costs, and improving product quality and consistency. EPD Congress 1994 Edited by C. Warren The Minerals, Metals k Materials Sodety, 1993

Jan 1, 1994

By Dany Racine, Daniel Marceau, Denis Laroche, Dmitry Lukovnikov

Carbon base materials play a critical role in the performance of Hall-Héroult cell. The determination of their thermo-physical properties is of primary importance for modeling and designing complete cell systems. However, overcoming the associated experimental hurdles is complex and often underestimated. Of them are the Poisson’s ratio measurements and the continuous oxidation/burning of the materials at temperatures above 200°C. The novel procedure developed in this research is based on the Gleeble® 3800 system. Its vacuum chamber allows test with a chosen atmosphere at temperature of more than 1000°C. Young’s modulus, Poisson’s ratio and the coefficient of thermal expansion values can all be adequately measured using a single test. Cylindrical carbon samples (: 50mm, L: 100mm) were tested in the modified system at temperatures ranging from room to 950°C without any trace of oxidation. The resulting values were also in good agreement with literature data for a specific graphite material.

Jan 1, 2015

By W. Murray Small

Nickel plays an important role in determining the properties of many stainless steels and superalloys. Cobalt also contributes significantly to the performance of certain grades of superalloys. A major technical aspect, in which both of these metallic elements are involved, concerns the solubility of nitrogen in these classes of alloys. Beyond certain content limits, dissolved nitrogen may contribute to the deleterious mechanical behavior by these alloys. It is therefore essential to control the level of this element during alloy processing. In this paper, results from several experimental studies have been assembled and are analyzed to describe phenomena related to the individual effects of nickel and cobalt on the solution of nitrogen in several groups of alloys. Both solid and liquid alloy systems are considered. This information may be used as a guide to limit or control the presence of this interstitial element in alloys.

Jan 1, 1993

By Edilson Marques Magalhães, Danielly Da Silva Quaresma, José Antônio da Silva Souza, João Nazareno Nonato Quaresma, Emanuel Negrão Macêdo

"The production of alumina from bauxite using the Bayer process generates the residue known by red mud. This material can be used as a source for concentration and recovery of valuable metals such as titanium. The greatest difficulty of concentrating titanium compounds is the large amount of iron oxide present in red mud > 30% by weight. This paper shows the extraction of the iron oxide, increasing the concentration of the titanium compounds. The red mud is leached with H2SO4 at 30% concentration and temperature range of 60°C, 80°C and 90°C. Analysis of the leached and concentrated was made to verify the effectiveness of the iron oxide extracting process and the titanium compounds concentration viability.2- IntroductionIn the state of Para is located the Industrial Unit Alumina of North of the Brazil S/A (Alunorte), created to produce and commercialize alumina, aluminum oxide, Al2O3. The ALUNORTE with Aluminum Brasileiro S/A (Albras) and Mining Rio do Norte S/A (MRN) complete the production cycle of aluminum in the state. Although the production of alumina has a importance great for the socio-economic status, as in any area other, generates a amount large of waste, thus causing environmental impacts. Pará State has produced 25 million tons of bauxite (Pinto, 2010), of which 60% were transformed into alumina plant in Pará and Maranhão by ALUNORTE by ALCOA, generating approximately 9,000,000 tons of waste known as Red Mud (RM). Due to the high reactivity this material is considered dangerous, and currently there is no operating process capable of reuse all the material produced at any refinery. The search for industrial processes in order to reuse these wastes can contribute to reducing the overall impact of the production process of alumina. In this context, this paper estudied, within the research line of Solid Waste valorization the mining industry and metallurgy, a process that makes possible the red mud as a source of raw material, in other words, seeks to maximize the use of red mud as raw material for concentration and or recovery of titanium compounds in both the crystalline form of anatase, rutile and ilmenite, avoiding the predatory extraction of natural resources of these materials. Applying definitely the concept of self-sustainability of the mining industry and metallurgy."

Jan 1, 2012

By Hua-qing Li

Electromagnetic stirring process effectively improves the casting quality of metals. In this paper, the physical simulation experiment, in which the molten copper is displaced by mercury, was designed. The factory test parameters were determined according the simulated data. The flow behavior of the mercury to be stirred as well as the relations between the microstructure of plate blanks and the current parameters were analyzed. With an appropriate electromagnetic stirring, the inverse segregation of tin for C51900 alloy plant blank reduces from 15 % ~ 30 % to about 5 %, and the proportion of equiaxed grain rises to larger than 30%.

Jan 1, 2009

By Marco Pasetto

The possibility to re-use marginal materials (by-products) deriving from industrial activities in the construction of road infrastructures, as total or partial substitution of natural aggregates, successfully combines demands for economy and environmental sustainability. The paper presents the results of a laboratory study, conducted at the Experimental Road Laboratory of the University of Padova, to verify the suitability of a particular type of electric arc furnace slag to be recycled in the lithic skeleton of high-performance asphalt mixes (porous asphalt, high modulus mixes, stone mastic asphalt, nonskid surfacings) for road and airport flexible pavements. the process of transformation of iron and steel slag into a product that can be used in road building is described, along with the characterisation of the mixtures, plus an analysis of the results of a wide battery of mechanical-performance tests. This study forms part of wider theoretical ? experimental research being done at the University of Padova in order to improve knowledge of the characteristics of succedaneum materials and check their possible applications in road and airport construction.

Jan 1, 2006

By Xiang Sun

Microwave processing has been under continuous development as an advanced heating method in modern industries. However, problems with uneven heating still remain. Although heating uniformity is highly dependant on the properties of the materials being heated, proper furnace design to prevent uneven field distribution is another important factor. As an alternative to experimental measurements and adjustments to find appropriate furnace parameters, computer simulation is a convenient method for modeling, understanding, and improving the uniformity of microwave heating. This paper discusses current modeling technologies as well as applicable techniques for improving microwave heating uniformity. The purpose is to give a basic understanding on how to find, analyze, and minimize the problems associated with uneven heating in microwave processing.

Jan 1, 2006

By Lucas Lopes da Costa, Sergio Neves Monteiro, Rômulo Leite Loiola

"Composites with DGEBA/TETA epoxy matrix reinforced with thinner and continuous bamboo fibers stripped from culms were mechanically characterized by tensile tests. Specimens with up to 30% in volume fraction of aligned fibers were tensile ruptured at room temperature. The results showed a steady increase in both the ultimate strength and the elastic modulus of the composites with the amount of incorporated bamboo fibers. The fractographic analysis by scanning electron microscopy showed evidence of moderate adhesion between the bamboo fiber and the epoxy matrix. This fiber/matrix adhesion by interaction mechanism apparently justifies the improved tensile properties of the composites.IntroductionIn recent years polymer composites reinforced with natural fibers, mainly those lignocellulosic obtained from plants, have been subject to extensive research works [1-5]. Environmental, economical, societal and technical advantages of these composites are motivating their substitution for similar polymer composites reinforced with synthetic fibers. In particular, R & D efforts have been conducted aiming to replace glass fibers composites that are comparatively more abrasive to equipments, non-recyclable, more expensive, heavier and toxic [6]. Among the many lignocellulosic fiber composites being investigated, those fabricated with bamboo stripped fibers, i.e., fibers longitudinally cut from the culm, still need information to support possible industrial applications. Several works, however, have been dedicated to bamboo stripped fibers as possible reinforcement of polymer composites [7-17]. These works reported mechanical properties that could markedly vary with the type of polymer matrix, the fiber disposition (if continuous, aligned, short-cut, mat interlayered, etc) and the test condition."

Jan 1, 2011

By Sue Ritz

Gold extraction has relied on coconut carbon in adsorption circuits for several decades. IXOS®, invented by 6th Wave Innovations of Salt Lake City, Utah, is a new type of adsorbent that exceeds the selectivity of carbon and improves on the mechanical properties of other available resins. IXOS selectivity against copper cyanide complexes allows it to be used in circuits that currently struggle with copper contamination. IXOS potential to eliminate or reduce the application of SART technology will expand the opportunities to exploit more complex precious metals deposits. This paper will describe the technology behind IXOS molecular imprint, its comparison to carbon adsorption in the field, and the effect of efficiency on long-term recovery from heap leach METSIM simulation software.

By Roberto Parra

The selective reduction smelting of Cu2O in Cu2O-FeOx-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260°C to 1350°C. The reduction rate by CO was found to be 10-2 to 10-1 mole Cu2O m-2s-1. The graphite reduction macrokinetics for FeO and. Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 104 to 10-3 s-1. The reduction rate was not sensitive to temperature nor to stirring, in the range studied. The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.

Jan 1, 1999

By Jan Petter Maehlen

Solid H-absorbing materials are in focus of ongoing R&D to offer viable solutions for the hydrogen storage and supply systems aimed on use of hydrogen as energy carrier for automotive transportation. Low operating pressures, combined with high gravimetric and volumetric efficiencies, together with fast kinetics of hydrogen release at ambient temperatures (providing conditions for a low energy loss due to decomposition), are the most important features of the ?ideal? H storage material. Hydrides of the light elements are the only possible candidates to build systems with an overall efficiency similar to those accommodating liquid or compressed (700 bar) hydrogen. One promising material from this point of view is aluminium trihydride, alane AlH3 with a gravimetric storage capacity of 10 wt.% H. This work was focused on studies of the crystal structure and thermal decomposition of alane by application of powder synchrotron X-Ray diffraction.

Jan 1, 2006

By David R. Sadedin

The highly negative Gibbs free energies of hydrogen atom reactions suggest that refractory oxides such as titanium dioxide should be easily reduced by hydrogen atoms. These reactions appear to be most favourable at low temperatures; oxides should be reducible even at room temperature. Since hydrogen atoms are produced in plasmas containing hydrogen a number of investigators have used hydrogen plasmas of various sorts to test these possibilities for reducing refractory oxides, in particular TiO2. None of these attempts has succeeded, a small degree of reduction being achieved in only a thin layer near the surface. A deeper consideration shows that several factors complicate the reactions expected on the basis of the negative Gibbs free energy. One factor is that the back reaction by water molecules produces molecular hydrogen, not hydrogen atoms, and the metal atoms that have been reduced may be immediately re-oxidised. In plasmas there are complications due to diffusion, thermal and charge boundary layers and charged particle reactions. Interpreting the results of hydrogen atom reactions is difficult. Hydrogen is not detectable by electron dispersive spectroscopy and amorphous products are not determinable by x-ray diffraction. Another consideration is economics. The cost of producing hydrogen atoms has a large bearing on the metals for which hydrogen atom reduction may be competitive. In this paper these factors are discussed, some necessary basic studies are highlighted and the general principles of a laboratory reactor are given, together with the results of tests using ZnFe2O4, ZnO and TiO2 as test oxides.

Jan 1, 2006

By Mick O'Meara

Metal Organic Chemical Vapour Deposition (MOCVD) is used in the production of computer circuit boards and metal shapes in nickel, gold, copper, cobalt, etc. All varieties of .MOCVD use the decomposition of a vapour of organometallic compounds to produce different forms of ultra-pure metals, or alloys. CVD Manufacturing's proprietary MOCVD process has been adapted and developed to produce commercially ultra-pure metal shapes, metal powders, and metal foams. Therefore, it is a purification process. The typical process has three steps. First, a volatile metal organic compound is produced from volumetrically contaminated metals, metal oxides, etc. Typical feed materials are metal powders, ores, concentrates, or a slurry of metals and contaminants. Secondly, the volatile. metal organic compound is purified by fractional distillation. Thirdly, the purified metal organic compound is decomposed into different forms of ultra-pure metals, such as net shapes, powders, or metal foams. A mixture of metals can be purified either by the selective production of volatile materials, or a separation can be achieved during the second step, in the fractional distillation stage. The purification and recycling of metals by the MOCVD process will be discussed, particularly with regard to nickel, aluminum, gold, the platinum group and other metals.

Jan 1, 2000

By Patrick R. Taylor

Glass is used for immobilization of radioactive and hazardous wastes due to its durability and ability to accept a variety of waste constituents into its network structure. Alternative high temperature vitrification techniques have the advantage of increased throughput, increased waste loading and being applicable to variable and heterogeneous waste streams. However, the increased processing temperature places further concerns on the increased volatilization of contaminants, and increased corrosion and erosion of me Iter components. A database of melt properties at higher temperatures, such as partitioning, viscosity, density and electrical conductivity, in the temperature range of 1400-20000 K are being developed.

Jan 1, 2000

By Marcio B. Fonseca

Nickel-cobalt laterite deposits have become the focus of attention for hydrometallurgical processing. Following the lessons of the second generation high pressure acid leach (HPAL) projects in Western Australia other Ni-Co laterite projects are now evaluating potential HPAL projects with a rigorous integrated approach that begins with geological modeling, resource estimation and metallurgical studies. The Vermelho nickel-cobalt laterite deposit has been under exploration and study for several years with investigations of various metallurgical processes. Recent HPAL studies have indicated that the nickel and cobalt laterite at this deposit is amenable to upgrading by silica rejection followed by pressure leaching. These studies have required a detailed geological investigation to generate a new resource model. The recent development of a sophisticated geological model integrated with a multi-element resource estimation for this complex tropical nickel laterite deposit in northern Brazil provides an example of the contribution of geology at the critical project stage where process technology decisions are made on relatively small samples of the total resource.\ Keywords: Ni Laterite, Geological Modeling, Resource Estimation

Jan 1, 2004

By Michael K. Rhodes

A 120 tonne per day BacTech bacterial oxidation plant treating refractory gold concentrates for Gold Mines of Australia's Youanmi project in Western Australia commenced operation September 1994. This was the first commercial application of the BacTech process. A pilot plant trial on concentrates produced from Youanmi ore was carried out at BacTech's laboratory in Perth. Results and measurements from this trial were used by Signet Engineering Pty Ltd to design the commercial plant. This paper cover the results obtained from the piloting, their implementation in the plant design and the initial commissioning of the full scale plant.

Jan 1, 1995

By Jaeheon Lee

Gold-copper alloys are shown to form during the cementation of gold on copper in a solution containing 0.25M [S2O32-] at 25oC. The alloy composition is strongly dependent on the initial Cu:Au ratio in solution and ranges from Au3Cu to AuCu3. XPS results for Au, Cu, S, and O are reported as a function of depth through an entire deposited film with an initial solution containing 20 ppm [Au] and 30 ppm [Cu]. The deposit contained about 20 atomic % gold and was predominantly Cu3Au. Underpotential deposition (UPD) theory is discussed as a mechanism for explaining the formation of these alloys. Several other systems that produce alloys during contact reduction/cementation are also discussed.

Jan 1, 2003

By Geir Wedde, Anders Sorhuus

"Vast quantities of energy are released as heat to the environment from industrial operations. Many countries target waste heat recovery to mitigate CO2 emission. Exhaust gases from industries such as primary aluminium smelting, carry a substantial portion of the waste heat generated. For a cost efficient capture of more valuable heat (higher exergy), heat exchangers should operate on the exhaust gases upstream of the gas treatment plants. Heat exchange surface would be exposed to dust laden gases with risk of fouling. Heat exchangers of innovated design and operation have overcome the potential of excessive fouling rates. Heat exchangers of the ""shell and tube"" design have been demonstrated for exhaust gases from ferroalloy as well as primary aluminium smelters. In addition to the heat recovery, gas cooling results in smaller gas treatment plants with lower costs and reduced emission. The aluminium experience is exampled in the paper.IntroductionIndustrial usage of energy continues to grow as a result of increasing volumes of production, a trend that is likely to continue in the coming decades as living standards keep rising globally. World energy consumption (Figure la) is to grow 49 % by 2035 (ref. 2010) as reported by EIA [1]. The industrial sector consumes somewhat more than 50% of the total world energy consumption predominantly the energy increased demand comes from non-OECD countries in Asia. The industrial consumption by production of metals iron and steel accounts for 14 % and for non-ferrous metals 3 % mostly for aluminium production (Figure lb). Aluminium production will be discussed in this paper as an example of an industry with large quantities of waste heat to recover"

Jan 1, 2012