Search Documents

By S. Pirzada, P. R. Taylor

A reactor was designed and constructed to perform experiments on the generation of value added products using a plasma heat source. The engineering drawings were developed to include multiple sample ports for temperature and velocity measurements and view ports were designed to allow the Physics group to make optical measurements. Two methods for feeding solids into the system were developed and installed. Preliminary experiments were performed to characterize the system at various flow rates and power settings. Experiments were performed using zinc metal and oxygen to form zinc oxide. The particles that were generated were characterized chemically using atomic absorption and x-ray diffraction; and physically using scanning electron microscopy. The particles appear to be of value added size; but there is a tendency for the fine particles to adhere to one another forming agglomerates. Additional experimental work will continue the evaluation of the major parameters.

Jan 1, 1988

By Boris Arlyuk

The system of short term forecast of metal prices at LME is based on correlation between prices within the quarter forward and at the first place by economic parameters at the West, determining the consumption of metals. Such economic parameters are presented by data of indexes of Western World industrial production (WW IP), official data of IP and Dow Jones indexes at USA. For price forecast within the quarter forward (one day ahead, 3 day -65 days MA forward prices) are significant the changes of actual prices (official and close) at the past and the parameters of daily trade at LME at the past (futures turnover, open interest, LME stocks). It is developed subsystem of price forecast within the quarter forward based on analytical approach determining the relations between the participants of the market. It gives the opportunity to reduce the number of empirical coefficients at the model and receive good accuracy of forecast the MA prices and its direction at the future. Very important part of short term forecast is subsystem determining analytically the probability that the price forecasted for the next trading day will be the maximum or minimum daily price within the quarter forward. The thresholds probabilities are defined by identification the model at the past by maximal commercial efficiency. Such system was tested at the past at period since 2000 till 2005 and gives very high commercial results at operations on 1M forwards and hedging the sales of nonferrous metals traded at LME (primary aluminium, light alloys, nickel, copper, zinc, lead and tin).

Jan 1, 2006

By Joseph C. Milbourne

The selection of a suitable nitrate removal process depends on a variety of site-specific chemical and environmental issues. The dominant technologies for nitrate removal include biological denitrification and continuous countercurrent ion exchange. The decision to apply either of these technologies, or both together, depends on the nature of the waste water to be treated. Factors that affect the selection of the biological system include the feed composition and feed temperature. Ion exchange nitrate removal systems are less sensitive to the feed composition but require disposal or destruction of the concentrated pregnant eluate. The paper discusses Tetra's continuous countercurrent ion exchange technology (CCIXTM) and fixed film biological reactor, Denite°. The treatment of the ion exchange pregnant eluant is also discussed.

Jan 1, 1994

By Joo Hyun Park, Kyu Yeol Ko

The viscosity of the CaO-SiO2-xMnO-yCaF2 slags (C/S=1.0; x=10, 40%; y=0 to 15%) was measured to clarify the effect of CaF2 on the viscous flow of molten slags at high temperatures. Furthermore, the Raman spectra of the quenched glass samples were quantitatively analyzed to investigate the structural role of CaF2 in a depolymerization of silicate networks. The critical temperature of the slags abruptly increased at 15%CaF2, which was confirmed to originate from a crystallization of cuspidine using XRD analysis. The viscosity of the slags continuously decreased by CaF2 addition in the 10%MnO system, whereas the viscosity of the 40%MnO system was not significantly affected by CaF2 addition. The effect of CaF2 on the viscosity of the slags was quantitatively analyzed using micro-Raman spectra of quenched glass samples accompanying with a concept of silicate polymerization index, Q3/Q2 ratio. A polymerization index continuously decreased with increasing content of CaF2 in the 10%MnO system, whereas it was not affected by CaF2 in the 40%MnO system. Consequently, the bulk thermophysical property of the CaO-SiO2-MnO-CaF2 slags was quantitatively correlated to the structural information.

Jan 1, 2014

By B. J. Beaudry

The preparation of alloys containing one to two percent of the volatile lanthanide metals Sm, Eu, Tm and Yb in the high melting point (HMP) rare earth metals Sc, Y and Lu was accomplished by a vapor deposition, diffusion method without crucible contamination. The method avoids the melting of the HMP metals which would introduce impurities from the crucible, generally Ta or W. Plates of the HMP metals were hung from the lid in the upper part of the Ta crucible. The volatile metals were placed on the bottom and the lid welded in place under an atmosphere of helium. By proper selection of thee alloying temperature, the effusion of the metal vapors, through the helium atmosphere was slow enough to permit diffusion to occur and prevent refluxing of the newly formed alloy. Very volatile metals such as Mg required a Knudsen cell with a suitably sized hole to prevent too rapid transfer of the low melting metal. Electron microprobe analysis of a cross-section of the HMP metals showed a homogeneous distribution of the volatile metals. The time and temperature required to obtain a homogeneous rare earth alloy without contamination are given. The use of a Knudsen cell to form magnesium-rare earth alloys is reviewed.

Jan 1, 1992

By Alessandra Bonoli, Garfìm Marianna

"Construction and demolition waste (CDW) is no dangerous material resulting from construction, and demolition of houses, large building structures, roads, bridges, piers, and dams. It is possible to recycle these materials, to reduce environmental impacts, and to reuse them in construction sector. To evaluate in a correct way the possibility to reuse this material it is important to lead laboratory tests to assess the proprieties and quality characteristics. European, Italian and British ad hoc Committees had elaborated specific Standards, to evaluate Geometrical, Physical, and Chemical requirements of recycled materials. A research was carried on to define the guidelines for laboratory tests, their suggested values and quality standards. The Construction and Demolition Waste Construction and demolition waste (CDW) is no dangerous, uncontaminated material resulting from construction, renovation, repair, and demolition of houses, large building structures, roads, bridges, piers, and dams. CDW waste is made up of wood, steel, concrete, gypsum, masonry, railway ties, roofing materials, carpeting, insulation, plaster, metal, and asphalt, and all waste included in CER Code 17. In particular Demolition wastes are defined as materials resulting from the demolition, instead Construction wastes are defined as waste materials resulting during construction process or in pre-manufacturing construction industry. Environmental problems In a lot of cases Construction and Demolition Waste materials were discharged in landfills, these are filling up with CDW and others, and some of them will close in the near future. In addition, illegal dumping of CDW debris can result in future health risks, decreased property values, cleanup costs and enviromental problems. The typical environmental impacts generated by CDW dumps are: 1- Dust problem, which causes air pollution, as will as forming dirty areas. 2- Uncontrolled locations, that will encourage the disposal of other waste types with the usual construction wastes leading to an environmental disaster. 3- The degradation and deterioration of the coastal lands and the natural protectorates. 4- The loss of aesthetic features. 5- Occupation of large areas, causing extra hauling costs. Therefore, it is wise to find other alternatives, like reuse or recycling, other than landfilling CDW debris or illegal dumps, because a proper management and the reduction of CDW amount can save money, conserve resources, and preserve the environment."

Jan 1, 2008

By Yasuhiro Konishi, Kazunari Mizoe

"This paper describes a new processing of ultrafine, magnetic ferrites from sulfuric acid pickling solution in steel industry. In the ferrite processing, the iron (II) in the pickling solution was first oxidized to iron (III) by using the acidophilic thennophile Acidianus brierleyi. The bio-oxidized pickling solution was treated with solvent extraction to separate the iron (III) into the organic solution of tertiary aliphatic monocarboxylic acid. After that, the carboxylate solutions of iron (III) and other metal (cobalt) were hydrolyzed and precipitated ultrafine particles of crystalline ferrites at l90°C and l. 3 MPa for 20 min.IntroductionHot-rolled steel sheet has always a layer of oxides on its surface. The oxide layer arises as scale in hot rolling processes in steel industry, and the scale consists of the three iron oxides such as hematite Fez03, magnetite Fep4, and wustite FeO. Pickling removes chemically the scale layer that adheres to the steel surface. For normal steels, pickling is carried out in 15-20% hydrochloric acid at 60-70°C or in 20-25% sulfuric acid at 95-100°C. When steel is pickled with sulfuric acid, the scale oxides dissolve to give iron (II) sulfate.Spent pickling solutions are hazardous wastes containing a large amount of dissolved iron (II) and sulfuric acid, e.g., about 40 kg/m3 of dissolved iron (II) at pH 0. In typical commercial processes, spent pickling solution is usually cooled evaporatively to 5°C, and then to 0°C to crystallize iron (II) sulfate as its heptahydrate. After the crystallization operation, the sulfuric acid can be reused in the pickling operation.In this paper we describes a new processing of ultrafine, magnetic ferrite from sulfuric acid pickling solution, in order to recover dissolved iron (II) in the form of a valuable product. In the ferrite processing, the iron (III) was first supplied by the microbial oxidation of iron (II) in the pickling solution, and then the biooxidized pickling solution was treated with solvent extraction to separate the iron (III) into the organic carboxylate solution. After that, the carboxylate solutions of iron (III) and other metal (cobalt) were precipitated crystalline ferrites under hydrothermal conditions."

Jan 1, 2000

By Masayasu Kawahara, Toshiyuki Kozuka

"Lorentz force, which has the functions of wave suppression and mixing control, is very useful for many metallurgical processes. In this paper, it is found that vertical Lorentz force which can change 'the gravitational force is able to modify the dispersion relation of the surface wave generated by gravity and also modify the instability phenomena on the interface so that the lower layer can be scattered into upper layers to realize the strongly mixed region.IntroductionIn metallurgical industries, recently, a new direction of process developments is required backed not only by severer operating conditions, e.g. small amount production, rapid refining, etc. but also by environment and energy problem. Because almost technologies in conventional processes have saturated, an innovative process, which can break the limits in the conventional processes, is now strongly required. Especially, controlling of mixing phenomena between two liquid phases is considered to be one of the most important technologies for the promotion of slagrnetal reaction, wave suppression, etc. On the other hand, electromagnetic forces which have various functions have been applied to many processes. And Lorentz force is able not only to suppress the wave motion of molten _metal surface but also to promote the mixing or separation of two liquids. In this paper, new controlling methods of mixing phenomena between two liquids are proposed, where a direct electric current and a stationary magnetic field are utilized. Vertical Lorentz force due to the interaction between the electric current and the magnetic field can modify the gravity force so that the dispersion relation of surface wave and the instability on the interface can be change to improve or develop the innovative processes(l,2).In case that a direct electric current is imposed on two liquid layers with a stationary magnetic field, Lorentz force of each layer becomes different due to the difference of electrical conductivity. If Lorentz force acting on the lower layer is stronger than that on the upper layer, resonance frequency of the wave motion on the interface due to the gravity can be shifted from the frequency of a outer disturbance to suppress the wave motion. And also, the lower layer can be scattered into the upper layer as liquid particles by an instability phenomenon."

Jan 1, 2000

By Mark L. Dietz

The unique physicochemical properties of room-temperature ionic liquids (RTILs) have led to intense interest in these materials as alternatives to conventional organic solvents in a range of synthetic, catalytic, and electrochemical applications. Recently, there has been growing interest in their potential use in various separation processes, among them the liquid-liquid extraction of metal ions. Although certain RTIL-extractant combinations (e.g., crown ethers in 1-alkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl] imides) have been shown to provide extraction efficiencies far exceeding those observed with conventional solvents, recent work suggests that the utility of RTILs may be limited by solubilization losses and difficulties in recovering extracted metal ions. In this work, we demonstrate that these limitations arise, in part, from differences in the mechanism of metal ion partitioning in RTIL systems versus conventional organic diluents and consider approaches by which they might be overcome.

Jan 1, 2003

By P. G. West-Sells

Recovery of gold from thiosulfate leachates can be accomplished by adsorption of the gold thiosulfate complex by a strong base resin. Two of the most significant impurities that can decrease this gold adsorption are tetrathionate and trithionate, which are produced as oxidation products of thiosulfate during gold leaching. This paper investigates gold adsorption on a strong base resin (Purolite A500C) as a function of the concentration of these impurities. It is shown that concentrations of tetrathionate and trithionate as low as 150 mg/L can decrease gold loading by an order of magnitude, and that of the two ions, tetrathionate has a stronger detrimental effect. The resin and solution gold concentration profiles were successfully fit using a Freundlich isotherm, which further shows the strong effect of tetrathionate. To counteract the decrease in gold adsorption by tetrathionate, a novel process was proposed. Sulfite was added to the solution to oxidize tetrathionate to trithionate, and a nitrogen blanket was added to ensure that no further oxidation of thiosulfate could take place. It is shown that by incorporating this process, gold adsorption was doubled from both synthetic and real gold thiosulfate leachates.

Jan 1, 2003

By A. V. Tarasov

Emission of sulfur-containing gases causes most adverse impact on the natural environment in the process of nonferrous metals production. Under the conditions of Arctic regions, in particular in the region of the Norilsk Mining and Metallurgical Complex (Russia), this problem requires a special approach taking into account potential economic and socioeconomic consequences. By reducing the iron sulfide content of flotation concentrates by using new flotation reagents inhibiting pyrrhotite flotation and by applying advanced process flowsheets for flotation it is possible to increase the nonferrous metals content of flotation concentrates by 5% or more along with a corresponding reduction in SO2 formation during their subsequent pyrometallurgical processing. The ways used to resolve the environmental problems in the Norilsk region in the process of nickel and copper production, are based on the improvement of methods for elemental sulfur recovery from metallurgical off-gas by non-conventional techniques, the sulfur recovery from metallurgical gases by production of liquid sulfur dioxide and the technology for pyrometallurgical treatment of sulfide concentrates without SO2 formation. Another opportunity is the development and commercial introduction of hydrometallurgical technologies for treating copper-nickel sulfide ores.

Jan 1, 2006

By Michael A. Krstich

A soil washing pilot plant to treat soils at the U.S. Department of Energy (DOE) owned Fernald Environmental Management Project (FEMP), was designed based on extensive bench-scale testing. The system's design incorporated a combination of physical separation and' chemical extraction processes and was tested on two soils. The textural composition of the two soils was approximately 20 percent sand, 60 percent silt, and 20 percent clay. Since this grain size distribution was not considered optimum for physical separation techniques, thesoil washing pilot plant had to be designed with selected equipment to provide specific soil size fractions during processing operations. A trommel, vibrating screen deck, centrifuge, and attrition scrubber were used in the system to selectively separate specific soil size fractions at 4.75, 2, 0.3, and 0.02 millimeters (mm). The trammel used high pressure water [1000 pounds per square inch (psi)] during the initial step of the process to reduce soil aggregates to single grain composition, separate out greater than 4.75 mm gravel, and dislodge chemical contaminants from the individual soil particles. The vibrating double-screen deck provided 2 - 4.75 and 0.3 - 2 mm soil fractions that, when combined, averaged greater than 75 percent solids for both soils. The centrifuge was designed to take the less than 0.3 mm soil slurry from the screen deck and produce a particle size of 0.02 mm. The centrifuge produced a high solids stream that averaged greater than 70 percent solids for both soils. These 0.02 to 0.3 mm soil solids from the centrifuge were combined with the 0.3 to 4.75 mm soil solids from the screen deck and processed through the attrition scrubber. The data collected from the pilot-plant operation was used to aid in the design of a full-scale system and was instrumental in formulating full-scale process operations and the selection of equipment.

Jan 1, 1995

By I. H. Bonekamp

Norddeutsche Affinerie has operated an Outokurnpu type flash smelter for more than 25 years. In recent years, the concentrate smelting capacity was increased to 750,000 tpy, double of the initial design capacity. Maintaining this high performance level requires very good metallurgical process control. It is not enough to base this control on thermodynamics and kinetics since the furnace is highly dynamic. Understanding these dynamics and being able to quantify them can have significant financial benefits. A mass and energy balance model was developed and is discussed based on measured data. At this time the model is based on the major elements copper, iron, sulfur and silica. With it is possible to quantify the differences of the various material streams such as matte, slag, flue dust, matte carry-over to settling furnace, etc. Comparing the reconciled energy balance model with the fundamental thermodynamic model makes it possible to quantify the dynamics. These dynamics are related to input parameters using methods such as statistics and neural nets. In the future this database will be used to improve the understanding of the dynamic process as well as the dynamic process control.

Jan 1, 1999

By Wan Entong, Xie Junlin, Jiann YangHwang, Yang Chengwei, Chen Junfu, Zhang Jianjun, Cao Tongyou, He Feng, Peng Zhugang, Fang De

During the solidification process of peritectic steel (PS), the peritectic reaction often causes volume contraction which associated with surface longitudinal cracks, and using mould flux with low heat flux density help for alleviating surface longitudinal cracks. New peritectic steel mold flux with Co2O3 doping reduced the heat flux density, and the optimal content was found to be 2.0 wt %. Furthermore, basicity and Na2O addition were designed, and the minimum heat flux density required basicity of 1.4 and 10.0 wt %. Na2O content. As a result, the optimal peritectic composition was CaO(35.67wt% ), SiO2(25.48 wt %)，Al2O3(3.7 wt %)， MgO(2.53 wt %)，Na2O(10 wt %)，CaF2(14 wt %)，Co2O3(2 wt %).

Jan 1, 2015

By L. Cifuentes

Electrodialysis (ED), i.e. a technique based on the effects of electrically charged membranes on ions in solution in an electric field, has been applied to Cu-Fe-As-Sb- H2SO4 electrolytes similar to those used in copper electrorefining and electrowinning operations. The effects of current density, time and species concentration have been studied in a batch ED cell. The technique has shown to be effective in concentrating and separating a range of ions and points to possible new methods of treating copper electrometallurgy effluents.

Jan 1, 1999

By I. D. Reznik

Regularities of cobalt and nickel distribution between slag and matte, slag and metallic alloy on the base of concepts on exchange reaction equilibrium are considered. It is shown that the distribution of cobalt and nickel in industrial processes approaches to equilibrium one. Oxysulphiae influence on the bahaviour of cobalt, nickel and sulphur is shown. The recommendations on conduction of the processes of smelting, converting and slag cleaning based on the analysis of the methods or" non : ferrous metal separation from iron are given.

Jan 1, 1993

By Edgar Blanco

A thermodynamic and experimental investigation to develop a new process for converting molybdenite concentrate to molybdenum dioxide by a water-vapor oxidation process was carried out. In addition, the behavior of rhenium and selenium in molybdenum concentrate during the process was investigated. The kinetics of the reaction were determined by measuring the weight change of a sample with time in water vapor at temperatures between 700-1000°C. The results were analyzed by a Shrinking Unreacted Core model under chemical reaction control, which showed an activation energy value of 102 kJ/mol. To determine the behavior of rhenium and selenium, their concentrations in the molybdenum sulfide and the product molybdenum dioxide were measured by the use of ICP. While most rhenium remained with the molybdenum dioxide after the water vapor oxidation, almost all selenium volatilized. These results agree with thermodynamic analysis.

Jan 1, 2006

By Carole Read

Hydrogen is under consideration by several countries for its potential as an energy carrier for transportation applications. In order to compete with vehicles in use today, hydrogen-powered vehicles will require a driving range of greater than 300-miles in order to meet customer needs and expectations. For the overall vehicular light-duty fleet, this dictates that a range of 5 to 13 kg of hydrogen be stored on-board (assuming a fuel cell power plant) within stringent system weight, volume, and cost constraints. Vehicular hydrogen storage thus constitutes a major scientific and technological challenge. To meet this challenge, the U.S. Department of Energy (DOE) initiated a ?National Hydrogen Storage Project? with roughly 40 universities, 15 companies and 10 federal laboratories, actively engaged in hydrogen storage research. Centers of Excellence in metal hydrides, chemical hydrides, and carbon-based materials have been established, as well as independent university and industry projects in the areas of new concepts/materials, hydrogen storage testing, and storage system analysis. Recent technical progress in each of these areas is discussed, as well as collaborative hydrogen storage activities under the recently established International Partnership for the Hydrogen Economy (IPHE).

Jan 1, 2006

By Moo Eob Choi

A new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and calcium sulfate without generating secondary pollutants was developed at the University of Utah. In this process, sulfur dioxide is reacted with calcium sulfide to produce elemental sulfur and calcium sulfate. The latter is reduced by hydrogen to regenerate calcium sulfide. In the present work, the effects of different pelletization conditions for the initial reactant calcium sulfate on the strength and reactivity of the pellets were determined. These conditions include the type, amount, and impregnation method of catalyst, binder amount, and sintering. Experiments were also performed to determine the effects of temperature in the range of 973-1173 K, pellet size, cycle repetition, and water vapor or carbon dioxide content in sulfur dioxide stream on the reaction rates of the cyclic process. Nickel-catalyzed fired pellets produced by the use of molasses or cement as a binder showed good reactivity as well as high compressive strength during the cyclic tests. The binder amount did not significantly affect the reaction rate.

Jan 1, 2006

By KNona Liddell

Many metal recovery processes Involve heterogeneous reactions In porous media accompanied by fluid flow and mass transfer. Modeling such systems Is difficult because of the number of rate processes Involved and is complicated even further by effects due to the structure of the porous medium. Data on even bulk properties of the medium are often severely limited or unavailable. For many such systems, a cell model may provide, an attractive alternative to models based on transport ,mechanisms in a differential volume. A cell model requires less input data and is computationally efficient. Identical residence time distributions can be obtained with models of both types, and both allow conversion and concentration profiles and histories to be calculated. The formulation and properties of cell models for metals recovery are described in detail.

Jan 1, 1996