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By Yuhsuke Mizukami

Crude high Cr containing steel such as tool steel, heat-resistant steel or stainless steel is produced by dissolution of high carbon ferro-chromium into molten crude steel. In the refining process, decarburization is performed at the first stage, and deoxidation is followed in the next stage. Therefore, the equilibrium relation between dissolved Cr and 0 in molten Fe-Cr alloy after decarburization is very important when yield of deoxidizer is considered for the ovemll control and optimization of the process. It is well known that the yield of deoxidizer does strongly depend on the kinds of refractories of furnace in the secondary refining process. In the present work, the equilibrium relation between dissolved Cr and O in molten Fe-Cr alloy has been measured in a Cr2O3, MgO or Al2O3 crucible at steelmaking temperature. O contents at given Fe-Cr components have been lower in order of Cr2O3, Al2O3 and MgO crucible. The present results have been discussed based on the activities of the constituents in pure solid Cr2O3, and FeO-Cr2O3, MgO Cr2O3 and (AI,Cr)2O3 solid solutions.

Jan 1, 2003

By D. N. Wilson

The potential risks of working with lead have been recognised for centuries, but it is only with the development of sensitive measuring techniques in relatively recent years that it has been possible to establish effective approaches for the monitoring and control of lead exposure. This paper examines the principal control measures employed today - lead in air and lead in blood - and reviews the evolution of numerical standards, with particular reference to the latest understanding of health effects. In addition to lead, a large number of other metals are commonly encountered when producing lead and zinc - both primary and secondary - and the health effects of many of these are discussed. Modern hygiene practices and technologies, which have proved successful in reducing worker exposures, are reviewed. The paper concludes with a look at how exposure standards are likely to change in the near to medium future

Jan 1, 2000

By B. J. Jody

Each year, about 11 million tons of metals (ferrous and nonferrous) are recovered in the U.S. from about 10 million discarded automobiles. The recovered metals account for about 75% of the total weight of the discarded vehicles. The balance of the material or shredder residue, which amounts to about 3 million tons annually, is currently landfilled. The residue contains a diversity of potentially recyclable materials, including polyurethane foams, iron oxides, and certain thermoplastics. This paper discusses a process under development at Argonne National Laboratory to separate and recover the recyclable materials from this waste stream. The process consists essentially of two- stages. First, a physical separation is used to recover the foams and the metal oxides, followed by a chemical process to extract certain thermoplastics. The status of the technology is discussed, and the process economics are reviewed.

Jan 1, 1994

By Herbert H. Kellogg

A model of the ISF is described. which reproduces with accuracy the "normal" operation of three industrial furnaces. The model, written in Fortran, is based on detailed heat and material balances, and the concept that the ascending gases reach equilibrium with zinc oxide and with the water-gas shift reaction. "Solution loss" of carbon in the lower shaft, and partial reoxidation of zinc vapor in the upper shaft are also essential features. For prediction of furnace behavior under altered operating conditions (blast rate, temperature, moisture content, oxygen enrichment, or injection of oil or coal through the tuyeres) the model modifies the heat loss, temperature of slag and bullion, amount of reoxidation in the upper shaft and the condenser efficiency to reflect the altered operating parameters. Model predictions for such operating conditions are in reasonable agreement with plant experience.

Jan 1, 1990

By B. Abedian, L. M. Racz, S. R. Berry, R. W. Hyers

"The presented work represents an effort to improve understanding and prediction of turbulent flow inside electromagnetically-levitated droplets. We show that the flow field in a test case, a nickel droplet levitated under microgravity conditions, is a low Reynolds number turbulent flow, i.e. in the transitional regime between laminar and turbulent. Past research efforts have used laminar, enhanced viscosity, and k - E turbulence models to describe these flows. In our study, we compare the RNG algorithm to laminar and k - E turbulence model results. We show that accurate description of the turbulent eddy viscosity µr is critical in order to obtain realistic velocity fields, and that µr cannot be uniform in levitated droplets. In the RNG method there are no characteristic length or time scales associated with the flow, thus allowing such anisotropic features to be captured. We perform calculations and analyses for two cases (1) a small, non-deforming, spherical nickel droplet and (2) a deforming, oscillating droplet. In addition to flow field calculations, we compare numerically-obtained surface tension and viscosity values to those obtained experimentally by the oscillating drop technique.IntroductionElectromagnetic levitation (EML) is a containerless processing technique for conductive materials. Its advantages are the avoidance of contamination or chemical reaction at container walls and the ability to perform long-term experiments in a metastable state. Because of its current limitation to small sample sizes, its primary use is in the laboratory. One application of interest is the measurement of thermophysical properties of undercooled liquid metals [1, 2, 3, 4]. In EML, a sample weighing approximately 1 gram is positioned inside an electromagnetic field generated by alternating currents flowing through an axisymmetric water-cooled copper coil. The coil must be designed appropriately so that thesample levitates in a stable manner.Traditionally, mathematical modeling has been performed in tandem with both earth-and spacebound electromagnetic levitation experiments, in order to determine the effect of the magnetic field on material and flow characteristics [5, 6, 7, 8]. These calculations are important because they allow design, planning, and correct interpretation of experiments. In addition, the calculations are of fundamental scientific interest, as they can be applied to other electromagnetic materials processing applications [9]."

Jan 1, 1999

By Kuniaki Murase, Tetsuji Hirato, Yasuhiro Awakura

"Electrodeposition of CdTe was studied using aqueous ammonia-alkaline electrolytic baths in which Cd11-and Te1V-ions are dissolving as Cd11(NH3)/+ and Te1vol-ions, respectively. Ca-thodic polarization curves of the baths suggest the presence of strong interaction between the Cd11-and Te1V-ions; electrodeposition of tellurium is inhibited by the presence of Cd(NH3)/+ ions. The interaction makes it possible to electrodeposit CdTe films with stoichiometric composition. Polycrystalline CdTe thin film of about 1 µm thickness was electrodeposited at 343 K from ammonia-alkaline solutions (pH= 10.7) containing TeO32-(<20 mmol dm-3) and Cd(NH3)/+ ( < 60 mmol dm-3) ions. Increasing Cd(NH3)/42+/TeO32- mole ratio or decreasing total concentration of ammonia/ammonium-ion gave flat and smooth crystalline CdTe deposits at constant cathode potential-0.70 to -0.30 V vs SHE at 343 K.IntroductionCadmium telluride (CdTe) is well-known as a compound semiconductor whose band gap, i.e. 1.44 eV, is suitable for solar energy conversion with a photovoltaic cell. Various methods, such as CVD (chemical vapor deposition) and electrodeposition, of preparing CdTe thin films for solar cells have been investigated.Acidic sulfate solutions with a pH of 1-2 are usually employed for CdTe processing by electrodeposition.1-3) The electrodeposition of compound semiconductors is usually achieved (i) at a higher cathode potential than the redox potential of less-noble species, can in this case, and (ii) under the condition of diffusion-limiting current of a more noble species, Te1Y.4) There-fore, a suitable CdII/TeIV concentration ratio in the acidic electrolytic baths, resulting in the deposition of stoichiometric CdTe, is determined by the diffusion-limiting current density of TeIV- reduction, i.e. the concentration of HTeIVO2+ · Since the solubility ofTe1v species HTeIVO2+ in the acidic solutions is quite low, the rate at which CdTe is deposited from the acidic solutions is extremely slow."

Jan 1, 1998

By Kaixi Jiang, Lan Li, Bang Wei, Haibei Wang, Yaping Feng

"China is currently the world's largest copper producer. In the last five years, 950 kt/y of smelting capacity was commissioned. Currently, about 1200 kt/y smelting capacity is under construction and about 2000 kt/y smelting capacity is under feasibility study. Ausmelt/ISA smelting and flash smelting technologies were commonly adopted in China. After the double-flash-smelter was first adopted in 2004, three new double-flash-smelters are scheduled. Recently, two new copper smelting technologies were developed in China. One is an improved bath side-blown smelting process, and another is the SK.S bottom blowing process. Both technologies have been in practice for over three years and have achieved good technical performance. Approximately 500 kt/y new smelting capacity in China and India will adopt these technologies. Both technologies have the advantages of low investment cost, low energy consumption and high flexibility for complex raw materials. This paper reviews ""green"" copper smelting projects in China and introduces the practices of the two new Chinese smelting technologies.IntroductionPresently, China is the largest copper producer in the world. As far as the smelting of copper is concerned, there are many smelting processes applied in industrial production, such as flash smelting, Noranda smelting, Ausmelt smelting, Isa smelting, the Mitsubishi process, Vanukov smelting, silver copper-smelting, SKS smelting, both side-blown smelting, traditional blast furnace smelting, electric furnace smelting, reverberatery smelting and so on . Except the last three traditional processes that are eliminated because of their failure to meet the requirements for environmental protection, all of the other above-mentioned methods are advanced smelting processes adopted nowadays."

Jan 1, 2012

By Ma Lijuan, Zhang Yubing, Wang Bo, Sun Huilan

The effect of lime ratio on phase composition and alumina leaching property of MgO-contained calcium aluminate clinker were investigated by analytical reagent, the XRD analysis of its mechanism was discussed. The results showed that: when the sintering temperature was 1350 ℃, C/A was 1.4, A/S was 1.3 and the content of MgO was 4%, the increase of the C/A promoted the formation of C12A7 and restrained the formation of Q-phase. The alumina-leaching ratio of the clinker (A/S was 1.3) was increased from 74.33% to 91.34% when the content of CaO was 5.21%.

Jan 1, 2015

By Raymond M. Coveney

Bedded sulfide ores in Cambrian Chinese black shales typically contains at least 2% Ni, 4.5% Mo, 1% As and 0.2% Se. Thin laminae and replaced on colites from the ore contain intimate mixtures of fine-grained Ni-rich sulfides and jordisite complicating ore treatment. The ores contain abundant jordisite, vaesite, nickelian pyrite, and barite and lesser amounts of sphalerite, gersdorffite, millerite, tennantite, fluorite, chalcopyrite, and HgSe (probably tiemannite). At present only ores that are sufficiently rich (>4.5% Mo) for direct roasting are mined and treated to produce, ammonium molybdate. The ores contain Pt, Pd, and Au in amounts totaling up to -2.5 ppm, but these are not recovered.

Jan 1, 1993

By M. Sakamoto, S. Karaswa, Y. Yoneoka, Y. Ohmizo

"The Annaka Refinery has been processing leach residue by Waelz process for 17 years. Recently, the quantity of the leach residue has increased due to a decline in the quality ~f zinc concentrate. Meanwhile, negative factors (e.g. deterioration of water balance due to improved electrolytic power consumption rate) have increased· in the processing of the leach residue.We have implemented various measures in responses to this situation, while striving to increase ·processing capacity and achieve stable operation. AS we have largely completed our assessment of the efficacy of these measures, we report on our recent process improvements.IntroductionWe have been treating leach residue by the Waelz kiln process since 1981. At that time, treatment of only 50,000 tons of leach residue per year was anticipated. However, subsequent process improvements have revised this figure up to 75,000 to 80,000 tons per year.However, today's increased Fe zinc concentrate grade has resulted in increased amounts of leach residue. In addition, improvements have reduced electrolytic power consumption rate of zinc electrolysis, limiting the amount of water that can be used in ·the zinc refining processes and for deaning leach residue. Consequently, we encounter an increasing number of problems and factors adversely affecting leach residue treatment, including increases in water-soluble Zn (WsZn) and. S (S04) in leach residue.To solve these problems, we have taken several measures to ensure long-term continuous operation and treatment of this increased · amount of leach residue. This paper discusses these measures."

Jan 1, 2000

By Hiroshi Tabuchi, Akihiko Takahashi

"High strength aluminum matrix composites were prepared and studied using as reinforcement newly developed nearly mono-dispersed a-alumina single crystal particles each of which has a regular polyhedral shape. The composites were formed by centrifugal casting using aluminum casting alloys (Al-Si and Al-Cu-Mg) as the matrices, followed by heat treatment. The volume fraction of the alumina particles was as high as 60%. The same matrix composites reinforced by conventional crushed fused alumina particles were similarly prepared as the reference. The bending strength and tensile strength of the Al-Cu-Mg matrix composites reinforced by the novel alumina particles of 10 µm in average diameter are as high as 1020 MPa and 560 MPa, respectively, which are higher than those of the conventional alumina composites. Furthermore, the bending strength of the novel alumina composites degraded less than that of the conventional alumina composites after thermal fatigue tests. The number of cracks in the matrix seemed to influence the thermal fatigue property because many cracks were observed in the conventional alumina composites, whereas only a few cracks were observed in the novel alumina composites. This was confirmed by SEM observation of the sample composites before and after the thermal fatigue tests.IntroductionAluminum matrix composites strengthened by dispersed reinforcements are of interest for various applications due to their improved properties, such as high specific strength and stiffness, wear resistance, etc .. A large number of investigations have been made concerning fabrication processes and properties of these composites. With regard to the fabrication processes, powder metallurgy has been well-known as a solid phase process, and recently many liquid phase processes such as a compocasting, a squeeze casting, the Lanxide process, and the Osprey process have been studied and developed.(1)"

Jan 1, 1998

By Nils Eivind Kamfjord, Roar Jensen, Ingeborg Solheim

"SINTEF has carried out several pilot scale silicon process experiments in the past, but always with an open off gas system. In order to test the possibilities in running a semi closed furnace operation, a new off gas hood has been designed and tested. The off gas hood is designed to collect all off gases to gain insight into the phase compositions in the off gas and at the same time have the opportunity to monitor and maintain the charging/stoking of the furnace. The furnace hood has regulation and control of the air inlet into the combustion zone in two different heights. The off gas temperature and composition was continuously monitored and analyzed during the experiment. In order to expand the knowledge on NOx- formation in silicon metal production, such information is vital.IntroductionBecause of the negative environmental impact, the attention towards all kinds of NOX emissions increases in Norway. The authorities’ demand towards better surveillance and control of emissions increases as well.Earlier and new industrial measurements in FeSi- and Si-metal furnaces reveal quite high NOX-emission. The measurements also show that the NOX formation (mainly as thermal NOX) is distinct connected to the formation of dust (SiO?SiO2) in the combustion chamber above the furnace surface, when the temperature is high and the access to N2/O2 is good. This means that stoking, charging and temperature straight above the furnace surface is important factors for the NOX formation."

Jan 1, 2012

By Michael Sheedy

Recoflo® ion exchange technology utilizes fine mesh resin beads, a fully packed resin bed, and counter-current regeneration. These unique features help to improve exchange kinetics, reduce regenerant consumption, and increase the concentration of strip solutions. Commercially, Recoflo technology has been extensively used in the following areas: the separation of strong mineral acids from dissolved metal salts, the purification, removal and recycle of dissolved metals in the surface finishing industries, and the production of high purity water. In the mining and metallurgical industries Recoflo ion exchange systems have been installed to treat a copper refinery bleed stream at Falconbridge&apos;s Kidd Creek plant and to treat a nickel and cobalt bearing ammonium sulfate effluent stream at another primary metal producer&apos;s facility. In the first application an APU® Recoflo system is used to separate the sulfuric acid at 200g/L from the dissolved copper and nickel sulfate salts at 80 g/L. The absorbed sulfuric acid is recovered from the resin by elution with water and is then returned to the refinery electrolyte circuit. In the second application a chelating ion exchange resin is used to remove nickel and cobalt at 0.01 - 3.0 g/L from process streams containing 120 - 240 g/L ammonium sulfate. This Recoflo system has been designed to reduce the nickel and cobalt levels to 0.001 - 0.002 g/L while recovering cobalt and nickel at concentrations up to 30 g/L and 15 g/L respectively. Case studies for both these metallurgical applications and other Recoflo processes are presented in this paper.

Jan 1, 1998

By A. R. Udupa

The reduction roasting behavior of chalcopyrite has been investigated using various combinations of a desulfurizing agent, i.e., CaO or Na2CO3, and a reductant, i.e., CO, H2 or C. Using these, combinations the sulfur is removed from the mineral as CaS or Na2S rather than SO2 as is the case with conventional copper smelting and converting. The laboratory reduction ex¬periments were conducted using thermogravimetric analysis (TGA) and boat tests of mixed combinations of fine particulate reactants subjected to a continuous gas stream. The degrees of metallization were determined by both weight loss and chemical analysis methods and the products examined using optical and scanning electron microscopy and electron probe microanalysis. The percent reduction after one hour at 900°C ranged from 60% to 94%. From these data It was possible to provide postulations as to the controlling reduction mechanisms.

Jan 1, 1983

By M. S. Moats

Galvanic stripping, in conjunction with solvent extraction, has been proposed as a technical option to the challenging problem of iron removal in certain hydrometallurgical processes. The galvanic stripping process is based on the ability of a solid metal to directly reduce ferric ion to the ferrous state in an organic media. Stripping the iron into the aqueous phase is then easily accomplished. Previous work has shown the reaction kinetics and efficiency are affected by such operating parameters as water and oxygen contents, temperature, time and metal reductant. In this study, the optimum operating range for some of these variables was determined. Both zinc and iron metal were used in the separate stripping of iron from D2EHP A. Reasons for the differences in the extent of the reaction obtained using the various conditions are discussed.

Jan 1, 1996

By M. Misra, J. Nanor

The precipitation and removal of arsenic from process waters can be accomplished with addition of lanthanum chloride alone or in conjunction with ferric sulfate. The long term stability of these corresponding precipitated compounds is critical from the disposal stand-point. In this paper the characterization of ferric, lanthanum and lanthanum-ferric arsenate compounds formed at room temperature in acidic and alkaline pH is presented. The characterization techniques used included zeta potential, XRD and SEM. Zeta potential measurements of ferric and lanthanum hydroxides in the presence of arsenate indicate that oxyanions of arsenate are chemically adsorbed onto the positively charged surfaces of these hydroxides. In alkaline pH there is desorption of arsenate species from the ferric hydroxide surface, hence the product is thought to be unstable. On the contrary, lanthanum arsenate is stable in alkaline pH. XRD patterns show that the ferric arsenate formed in acidic and alkaline pH is amorphous, whereas lanthanum arsenate and lanthanum-ferric arsenate formed in acidic and alkaline pH are crystalline.

Jan 1, 1999

By Caisa Samuelsson

Experimental studies in laboratory-scale equipment have been carried out to study the vaporisation from dust generated during the copper converting process. In the present work the vaporisation of Zn, Pb, As, Sb, and Bi from a dust collected in the electrostatic precipitator after the copper converter were studied. The results show that Pb, Bi and As were vaporised to a high degree from the dust at a temperature above 900°C in a gas containing N2, SO2 and a small amount of H2. The vaporisation was high for these elements also in a gas containing N2, SO2 and 02 at temperatures above 1120°C. In an earlier study, thermodynamic calculations showed that it is possible to selectively condense metals at high temperature&apos; in a gas atmosphere generated during a copper converting process. The present study was carried out to verify the thermodynamic model. The results indicate that it should be possible for a selective condensation of Zn at high temperature. The temperature required for a selective condensation of Zn is dependent upon the gas atmosphere, e.g., the oxygen potential.

Jan 1, 1998

By Chuan-fu Zhang

Li(Nil/3Col/3- xMnl/3)MxO2(M=Ti, Mg) cathode materials were prepared from LiOH?H2O and oxalate precursor. The physical and electrochemical properties were studied by XRD, SEM, cyclic volt-ampere (CV), AC impedance and constant current charge-discharge. The results show that crystal volume of Ti4+ or Mg2+ doped sample is increasing and the electrochemical reaction resistant Rct is decreased at high rate, improving the cyclic performance and rate capability. The effect of Ti4+ doped is better than Mg2+. The sample is well crystallized and simple pure phase with a-NaFeO2 layered structure when doping quantity x=0.025. The second specific discharge capacity of Li(Nil/3Col/3- 0.025Mnl/3)Ti0.025O2 is 143.2mAh/g at 1C,128.0mAh/g at 2C in the voltage of 2.75-4.3V,and still has 140.7mAh/g and 121.7mAh/g after 20 cycles, respectively, keeping 98.25%, 95.07% capacity.

Jan 1, 2009

By John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

By Dale W. Collins

The disposal of arsenic from copper operations possess various health, environmental and processing problems. There are basically two areas of concern. The first being the disposal or treatment of smelter flue dusts and the second the removal of arsenic from refinery electrolytes. A number of treatment options have been proposed including the addition of soluble arsenic wastes to copper heap and dump leaching solutions. This approach will allow arsenic to be reintroduced to the ore via Solvent Extraction (SX) raffinate associated with hydrometallurgical operations. Knowledge of the attenuation behavior and mechanism during leaching is important in determining the long term stability of arsenic and the success of this approach. Parameters, such as uptake capacity, pH, particle size and solution chemistry have been investigated. Arsenic attenuation has been examined using column leaching with experiments employing both continuous flow and pulsed additions of As(V). In the initial stages of leaching, the attenuation of arsenic appears to depend on the pH and iron concentration in the effluent. Arsenic stability in the copper oxide ore has been examined with rinses of progressively lower pH.

Jan 1, 1994