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By Brian Lightfoot

Ausmelt Technology uses a furnace/slag/lance system in a way analogous to the way a chemical engineer would use a mixed reactor. The technology is sufficiently versatile to treat materials under a very wide range of temperature and chemical conditions. At one extreme the system has been operated at temperatures high enough and oxygen potentials low enough to make iron. At the other extreme it has been operated of temperatures as low as 800°C and oxygen potentials high enough to cupel lead from silver. This versatility permits the treatment of a great variety of wastes including asbestos, mixed organic\heavy metal wastes, incinerator ash smelter residues, waste water treatment sludges, organochlorine compounds and many others.

Jan 1, 1994

By Robert F. Jenkins

This document addresses the use of practical and basic engineering principles to develop a computer model for the analysis of the various issues which affect heat transfer in aluminum sidewell furnaces. These issues include furnace charge conditions, furnace operating conditions, furnace general arrangement, furnace combustion conditions, and furnace ambient heat loss. The engineering principles applied to this model were first put to test over 20 years ago. A prototype computer model developed 12 years ago has been in continuous use by Thorpe Technologies to determine the performance of sidewell furnaces for the aluminum industry. A new computer model has enhanced capabilities for more detailed performance analysis including regenerative and oxygen enriched combustion.

Jan 1, 2000

By Varadajan Seshadri

Keywords: torpedo car, kinetics, physical modeling A 1:6 torpedo car physical model was built to assess the optimum refining conditions for pig iron desulfurization in the torpedo car considering the industrial parameters used in the steel plant CSBM (Companhia Siderurgica Belgo-Mineira, João Monlevade, MG, Brazil). The refining practice in this plant is through injection of a CaO-CaF2-Mg powder in the pig iron melt. Similarity between the model and prototype were established through Froude and turbulent Reynolds criteria. Mixing times were evaluated by pulse tracer addition and the kinetics of metal/slag interactions were assessed from experiments investigating iodine transfer from kerosene to water. The influence of parameters such as level of metal, gas flow rate, lance penetration, lance orientation were also evaluated.

Jan 1, 2005

By Iris Filzwieser

The secondary copper producer, Montanwerke Brixlegg AG (Austria), produces 73 000 tonnes of cathodic copper per year using ISA tankhouse technology. METTOP GmbH (Austria) evaluated the different anode qualities from the plant with relation to the current efficiency and specific energy consumption. Parameters including the chemical and physical anode quality, current and current density distribution at each cathode, voltage, and distance between each cathode and anode were examined. In addition, the temperature, chemical analysis, and conductivity of the electrolyte was determined for each investigated cell, as well as the anode weight, anode scrap, cathode sheet, and short circuits. Metallographic analysis was also performed on selected dendrites. The investigations resulted in specific improvements in the tankhouse process including the level of anode impurities, and future projects are planned for further tankhouse optimization.

Jan 1, 2006

By Alwin Frei, Aldo Steinfeld, Peter G. Loutzenhiser, Enrico Guglielmini

"Using concentrated solar radiation as the energy source of high-temperature process heat, the carbothermal reductions of Al2O3 to Al and SiO2 to Si were examined thermodynamically and demonstrated experimentally at vacuum pressures. Reducing the system pressure favors Al(g) and Si(g) formation, enabling their vacuum distillation and avoiding contamination by carbides and/or oxycarbides. Exploratory experimentation in a solar reactor was performed with mixtures of charcoal with alumina and silica in the ranges of 1300-2000 K and 1997–2263 K, respectively, at 10-3 bar by direct exposure to concentrated thermal radiation. Distilled samples contained up to 19 wt% of Al in Al-Al2O3 mixtures and 79 wt% of Si in Si-SiO2 mixtures. When the reducing agent is derived from a biomass source, the solar-driven carbothermal processes are CO2 neutral.IntroductionMetallurgical extractive processes for producing Al1-2 from Al2O3 and Si3-6 from SiO2 are characterized by their high specific energy consumption and concomitant emissions. Alternatively, concentrated solar energy can be used as a high-temperature heat source to drive the carbothermal reductions and, thus, avoid greenhouse gas emissions and other pollutants derived from fossil-fuel-based processes7-12. When the reducing agent is biomass charcoal, the solar-driven carbothermal reduction is CO2 neutral. The carbothermal reductions of Al2O3 and SiO2 are represented by the simplified overall stoichiometric reactions:"

Jan 1, 2011

By Hanlu Xie, Liang Yu, Ping Wang, Yuanchi Dong

"The leaching process is the first step when recycling BF slag as raw material for some other products. While studying the kinetics of the BF slag leaching process, a fractal phenomenon was found, which indicated some interesting mechanism in the process. The result suggested a new understanding of the leaching process in detail which useful for the industrial applicationIntroductionTypical composition (wt. %) of blast furnace slag varied in a pretty wide range: SiO2 30–40, Al2O3 10–20, CaO 30–40, MgO 5–10.The ground granulated slag is commonly used as base of roadway (mixed with natural inert for paving, soil stabilization, etc.) or one of the resources of Portland cements because of its good hydraulic activity [1]. To recycle the slag economically, the selective recovery of some components of the slag may be considered. As main components exist in the slag, silica [2, 3 and 4] and alumina [4] recovery was first considered.While recovering of silica from the slag, silica gels are recovered selectively from the leaching solution deriving from the treatment of the slag with waste sulfuric acid. After separation of the exhausted solid of leaching, the silica gel is precipitated from the solution at pH 3.2. Although the silica gels obtained by this procedure contain many impurities and need some more work afterward, it is the first and important step for the process.In the prior work [5], silica extraction using blast furnace slag had been investigated, focused on the pH value of selectively silica extraction. In the present work, kinetics of the leaching process was focused. It is important to design an economical process.ExperimentalThe composition of the slag and the calcined gels has been determined by a LINK860 (Oxford Instruments, Oak Ridge, TN) energy dispersive spectrometer (EDS) in conjunction with a CAMBRIDGE S250-M2 (Cambridge Instrument Ltd., Cambridge, U.K.) scanning electron microscope(SEM). The leaching of slag and the precipitation of silica gels have been conducted at atmospheric pressure in a stirred reactor placed at temperature controlled by a heated water bath."

Jan 1, 2008

By Toyohisa Fujita

The effect of variables on the gold extraction with ammonium thiosulfate was investigated on sponge gold and ore samples. The Effects of CUS04, (NH4hS203, NH40H, (N~hS04' pH, stirring speed and retention on gold leaching rate and thiosulfate oxidation (consumption) have been studied. Almost 100% of gold was leached from sponge gold and over 96% from ore sample at optimum conditions. Trioctylmethyl ammonium chloride was used to recover gold from thiosulfate pregnant solution. It was found that more than 99% of gold was recovered by the extractant diluted with n-octane at 01 A ratio of 1: 1 without the re-adjustment of pH or others. Also, the gold cementation was conducted without de-aeration by using zinc, copper and aluminum powders. The result indicated that the gold was effectively recovered from a solution of low ammonia and copper concentrations and higher thiosulfate concentration. The gold recovery process by using ammonium thiosulfate is an environmental friendly method comparing to conventional cyanidation process.

Jan 1, 2003

By J. Rajek

The novel multi-component, multi-particle, multi-phase precipitation model developed recently is used to predict the precipitation kinetics in complex 9-12% Cr steels investigated within the European COST 522 project. These steels are used for tubes, pipes, casings and rotors in USC (ultra super critical) steam power plants for the 21st century. In the computer simulations, the evolution of the precipitate microstructure is monitored over the entire production heat treatment starting with the casting process, including austenizing, several annealing treatments and in-service conditions. The main interest lies on the concurrent growth and coarsening interaction of different types of precipitates. Keywords: Precipitation kinetics, heat treatment, power plant steels, simulation

Jan 1, 2003

By A. V. Tarasov

In order to improve technical, economic and environmental performance of hydrometallurgical processing of intermediate products containing copper and nickel, the Gintsvetmet Institute and the IMET Institute of the Russian Academy of Sciences have conducted studies into the efficiency of the use of alternating current of industrial frequency on processes applied for hydrochemical leaching of various copper- and nickel-containing materials. It has been found that: 1.Imposition of alternating current over the process of leaching of softly reduced nickel oxide with recycled copper sulfate solutions resulted in an increase by 20 to 30% of the rate of the copper cementation process and reduced by 20% its activation energy. At the same time, the recoveries of nickel, cobalt and iron to the leach solution increased up to 82.2%, 78.5% and 57.1%, respectively, and that of copper to the cement precipitate up to 74%. Optimal process conditions have been identified with respect to the current density, electrode material, copper concentration in solutions and the process temperature. 2.In the process of hydroelectrochemical sulfuric acid leaching of nickel and copper sulfides, the grain size, the phase form of sulfides, the solution composition (H2SO4, Cl?, Cu2+, Fe3+)and the current amperage had an effect on the nickel recovery to the solution, which reached 90%, while the degree of copper transfer to solution did not exceed 20%. The process of hydroelectrochemical sulfuric acid leaching of nickel and copper sulfides with an addition of Cl? made it possible to selectively recover nickel into the leach solution along with concentrating copper in the leach residue. 3.When subjecting samples of commercial-grade magnetic fractions of converter matte to sulfuric acid leaching, the imposition of electric current, the concentrations of sulfuric acid and chloride ion in the solution and the duration of the reaction process had an effect on the process. The nickel recovery was 85% and that of cobalt and iron was 95% and the recoveries reached 97.5%, 98.3% and 99.8% as a result of repeated treatment of the primary residue under similar process conditions. Up to 75% of copper, 75% of sulfur and 99.0-99.5% of palladium was concentrated in the solid reach residues. The experimental data obtained indicates that the use of AC for hydroelectrochemical sulfuric acid leaching for separation of copper- and nickel-containing intermediate products has favorable prospects.

Jan 1, 2003

By Farzaneh Sadri

After water leaching of an acid baked REE concentrate, impurities such as Fe, Al, Th, and Cu are removed by neutralization with different reagents such as NaOH, Mg(OH)2, MgCO3, CaO, and CaCO3. Among these chemicals, lime (CaO) and limestone (CaCO3) are the preferred reagents due to their low costs. However, because of calcium sulfate dihydrate (gypsum) precipitation, they are not so common in industry. One of the disadvantages of gypsum precipitation is the adsorption of REE to the precipitates, losing a fraction of REE to gypsum which is hard to recover. In this paper, batch and continuous conditions in the impurity removal process using limestone are investigated and the differences between these two processes are examined. Based on the experiments, REE uptake by gypsum significantly increases in continuous processes, and different gypsum morphologies are observed.

By A. D. Neuman, C. C. Davis, M. R. Lopez, A. C. Martinez, T. A. Nothwang, S. L. Voit

"One of the thrust areas for the Global Nuclear Energy Partnership (GNEP) program is the development of actinide bearing fuels for transmutation in a fast reactor. Mixed Oxide (MOX) fuel has an extensive fast reactor irradiation history and thus is being considered for use as a baseline composition from which minor actinides (MA) can be incorporated for use as a transmutation fuel. This study involves characterization of precursor powders and pellets to be inserted into the Advanced Test Reactor in Idaho. These pellets will have three compositions: one standard MOX composition, (U80Pu20)O1.98, and two compositions of MA-MOX with oxygen to metal ratios (O/M) of (U75Pu20Am3Np2)O1.98 and (U75Pu20Am3Np2)O1.95. The precursor powders, which consisted of, highly enriched uranium oxide, HEUO2, depleted uranium oxide, DUO2, neptunium oxide, NpO2, americium oxide, AmO2, and plutonium oxide, PuO2, were characterized using a field emission gun scanning electron microscope (FEG-SEM) for particle morphology, size, and size distribution prior to pellet production.IntroductionThe Global Nuclear Energy Partnership (GNEP) was created in order for “fuel-cycle supplier” nations to provide assured supplies of nuclear fuel to “fuel-cycle customer” nations. The customer nations would utilize the fuel for electricity generation and subsequently return it to the supplier nation after it is spent. This spent fuel would then be reprocessed by the supplier nation in order to recycle the actinide constituents, mainly uranium and plutonium, in advanced nuclear power reactors, and thus reducing waste volumes [1, 2]. Nuclear materials would also be strictly controlled through the International Atomic Energy Agency. One of the thrust areas for the GNEP program is the development of these actinide bearing fuels for transmutation in a fast reactor under the U.S. Advanced Fuel Cycle Initiative (AFCI) in order to transmute long-lived transuranic actinide isotopes into shorter-lived fission products [3]."

Jan 1, 2008

By M. J. Adam

As part of its research program, the U.S. Bureau of Mines is investigating the partitioning of complex minerals to simpler phases using sulfidation reactions for selective extraction of mineral constituents of value from extraneous elements early in processing schemes. This report describes research in which thermal processing of the complex Ti -bearing mineral ilmenite (FeTiO, ) resulted in partitioning of the valuable Ti metal to the simpler compound rutile (Ti0 ). Samples of ilmenite were blended with elemental S for thermal treatment a2 various temperatures under controlled atmospheres in an effort to dissociate the Fe from the ilmenite complex. Product characterization revealed that the Fe was partitioned from the ilmenite, forming a rim of pyrrhotite/pyri te (FeS/FeS,) on a rutile core. The products were agate milled and then subjected to cursory magnetic and flotation techniques in an attempt to physically separate the partitioned phases. Partitioning results and phase concentration data are reported relative to thermal treatment variables and physical separation techniques.

Jan 1, 1993

By G. Springer

The identification of lost mineral values in mill tailings frequently requires the inspection of hundreds of thousands to millions of particles. The search of these particles can be made automatic by using an electron microprobe. A standard instrument (Cambridge Mark V) was modified by the addition of stepping motors to advance the specimen stage in a controlled manner. The X-ray Signal is monitored continuously by a computer interfaced to the instrument with an analog-to-digital converter. 400,000 particles of a tailings sample can be scanned in about 3 hours. Particles as small as 2 um and containing as little as 3% of a particular element can be detected.

Jan 1, 1982

By Kanchan Mondal

"Methanol, lower hydrocarbons, CO, and HCOOH formation have been by the reduction of CO2 with H2. Un-catalyzed electro-reduction requires a significant overvoltage. An alternate route has been conceptualized. Production of hydrogen from water can be achieved by chemical oxidation of a metal in water followed by oxidation of the hydronium ion by the released electrons to form hydrogen radical. It is hypothesized that circumventing the problem of the formation of hydrogen molecule is essential while having the hydrogen radical to react with CO2 forming methanol, etc. This may be possible by a bimetallic catalyst acting as a galvanic couple, wherein one metal acts as the electron donor for the production of hydrogen radical while the other acts as a catalyst for the reduction of CO2. This may enhance the reaction rates. The current concept circumvents the need for an external electric field unlike the electrochemical process.IntroductionUtilization of carbon dioxide as a raw material, not only as carbon sources but also as useful chemical feedstock is a more holistic approach to reduce air pollution by flue gases (1-3). Several methods have been proposed to maintain the concentration of atmospheric CO2 or to reduce and recycle it. One of these is the chemical fixations using catalysts. The conversion of CO2 to methanol by hydrogenation over copper containing catalysts is one of the most widely studied subjects in this area. The limitation in this reaction is the low conversion of CO2."

Jan 1, 2008

By R. T. Hernández, I. Hilerio, A. Altamirano, M. A. Barrón

"The principal objective for finishing surfaces is to protect and/or to decorate them. This can be achieved by adding or removing material from the work surface. The addition of aggregated material is called coating or recovering. In this work, mecano-chemical techniques are investigated for surface finishing. For these techniques, barreling or polishing by the friction method will be used. These are the cleaning or finishing processes most used for great volumes of small pieces. These methods improve the surface finishing by eliminating burrs, sharp pointed, tool marks and crusts of casting. They are used to clean metallic pieces, ceramics and polymeric materials. The process is based on rubbing or friction by abrasives. The pieces are arranged in the barrel with an abrasive and an additive (water or chemical additive). The machine produces a rotating movement on the pieces. When the abrasive passes against the surfaces of the pieces, it produces an action of rubbing and impact that cleans the surfaces. The rubbing action is developed when the upper layer of the charge slides to the lower extreme when the barrel rotates. The barrel can be hexagonal or octagonal to facilitate the sliding of the charge. The barrels can be between 15 to 120 cm in length and they can have almost any diameter and velocity of rotation. There are several types of barrel: individual, multiples, and multiple compartments. The barrels are rotated using a wheel spindle or rolling pins, that the can ride horizontally or be tilted to produce an additional movement of the charge.IntroductionShot penning is a cold method in which compressive effects are induced on an exposed surface of a metallic piece, by the impact of a rain of shots directly on the surface of the metal, at great speed under controlled conditions. This differs from cleaning with the help of air, because even when shot penning cleans the surface of the metal, this function is incidental. The main purpose of shot penning is to increase the resistance of the piece to fatigue. The process has other applications: raises the tensile strength and decrease corrosion fracture."

Jan 1, 2012

By Kazuyo Yokoyama

New environmental assessment model based on the Waste Input-Output analysis has been developed and applied for the "Landfill mining activity". "Landfill mining" implies the digging up of the landfilled wastes, the recovery of valuable material and energy resources and, thus, the reuse of the saved space as a new landfill site. In this study, the landfilled wastes are assumed to be treated by the gasification/melting processes. Two kinds of reactors, the fluidized bed type (FB) and the shaft furnace type (SF), have been considered in this work as the typical gasification/melting processes adopted in Japan. In FB, the dug-up wastes are heated in the sand fluidized bed zone under reducing atmosphere, Fe and Al are recovered in the metallic form, and then, the gasification/melting of residues is made in the second zone. In SF, the waste is charged in the high temperature coke bed, and the gas is recovered together with molten metal and slag. Both processes generate electric power by the recovered heat and fly ash as waste to landfill. It has been found in this study that the both processes can reduce the total volume of waste and save the available landfill space. SF seems to have higher potential for decreasing volume of wastes because of less emission than FB while FB has great benefit to recover metallic Fe and Al individually. The results of scenario analysis have also indicated that the landfill mining activity is effective for sustainable management of landfill sites.

Jan 1, 2006

By Fumito Tanaka

The Mitsubishi Process is the sole pyrometallurgical process for the continuous production of blister copper from copper concentrates. Continuous converting originates from the application of the proven technology of a lime-ferrite slag (CaO-FeOX-Cu2O) on the Converting Furnace (C-furnace). Recent improvements on the C-furnace operation have included increasing the processing of recycled materials and the investigation of alternative fluxing agents. However, some minor oxides adversely affect C-furnace operation, with respect to magnetite behavior of the slag, with the most significant impact having been observed with the silica content of the slag. This paper will quantify the impact of silica on the lime-based slag, and discusses the controls that have been identified to sustain continuous converting operation.

Jan 1, 2005

By Ephraim Jeya Kumari

The demand for the titanium dioxide pigments and the shortage of higher-grade titaniferous ores with low radioactivity and zircon sands worldwide has encouraged the development of new techniques for the beneficiation of lesser grade titaniferous ores. The inferior quality ores are invariably richer in radio-active and lanthanide oxides, which severely interfere with the fluidized bed chlorination reaction (FBCR), in which ultra-high purity titanium tetrachloride is distilled off for pigment manufacture. However the present beneficiation techniques require high quality ilmenite ores and are not suitable for upgrading lower grade ilmenite ores which do posses trace metals in the form of lanthanides and actinides as Al-phosphates and zirconium silicates, respectively. The presence of mineral hosts, zircon sand and monazite in ilmenite and anatase also increase in chlorine gas consumption in the FBCR and contribute to a larger volume of hazardous waste production, which must be neutralised at a significant cost before being disposed off safely. In view of the problems described for lanthanide (Ce, Nd etc) and actinide (Th, U) trace impurities in titaniferous ores, an alternative route, which is flexible and more accommodating for processing difficult ores, is discussed. In the new process, which may be used for richer grades of ores too, the ore is roasted in air with sodium carbonate below 950°C to promote the formation of water-soluble sodium ferrite and insoluble sodium titanate phases. In this investigation, the high-temperature roasting process and the ensuing hydrometallurgical leaching steps have been analysed in the context of selective separation of lanthanide and actinide minerals from the main titaniferous mineral structures. Evidences for the selective separation are presented based on the chemical (XRD, XRF, AA) and microstructural analysis (SEM, EDX, EPMA) of roasted mass and the leached product. The efficiency of selective separation is also reported based on the chemicals analysis and the particle size of the materials derived after leaching. The paper highlights the various thermodynamic aspects of reaction equilibrium in the Fe-Ti-O-Na system, and the effect of Eh-pH diagram in the determination of pH required for the better control of the removal of iron and sodium. Two different types of Ti ores, namely ilmenite and anatase, their crystal structure and the phase transformation will also be explained on the basis of wet chemical analysis, XRF, XRD, EPMA and SEM-EDX studies. The method developed examines the technological feasibility of the selective separation process.

Jan 1, 2006

By Chen L. Lin

Scientific visualization is an ideal methodology for investigating complex phenomena that are characterized by large amounts of data. Furthermore, it is invaluable in the study of processes that evolve in time. Scientific visualization relies heavily on computer graphics, image processing and video technologies. Specific applications of scientific visualization in the minerals and materials processing fields that are considered in this paper include: 1) applied CT technology for multiphase materials and minerals, 2) time averaged density profla in air- sparged hydrocyclone (ASH) flotation and 3) dynamic motion analysis of ball mill grinding.

Jan 1, 1993

By Wellington Pereira Inácio, Fernando Wypych, Sergio Neves Monteiro, Artur Camposo Pereira, Rafael Marangoni

"The efficiency by which an applied load is transmitted from the matrix to reinforcing fibers in a composite depends on the fiber/matrix adhesion strength. This is determined as the interfacial shear strength, IFSS, which may be measured by means of pullout tests that measure the force needed to pull a single fiber out of a block of material simulating the composite matrix. Different techniques are used to perform pullout tests. The objective of this work was to characterize the IFSS of sisal fibers embedded in epoxy matrix through the determination of the critical length pullout curves. As the main results, a relatively small critical length was found for the sisal fiber/epoxy pullout specimens, corresponding to a weaker IFSS. This was compared to other results applying different pullout techniques. Scanning electron microscopy observation identified the mechanism responsible for the weak sisal fiber adhesion to the epoxy matrix.IntroductionSynthetic fiber reinforced composites is today one of the most successful class of materials with increasing industrial applications from house appliances to large airplanes like the modem Airbus 380. However, environmental issues are revealing serious drawbacks related to the fabrication, use and post-use discard of these composites. For instance, the thermoset polymer composite reinforced with E-glass fiber, known as ""fiberglass"" has an energy-intensive fabrication associated with a surplus emission of C02, which is responsible for global warming [1]. Moreover, the glass fiber is considered toxic and also causes long term pollution after being discarded."

Jan 1, 2011