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By K. Yamaguchi, Y. Takeda

"Partial pressure - temperature - composition correlation diagrams of the Ga-As, In-As, Ga-P and In-P systems were contracted based on the obtained experimental data of the phase diagram and thermodynamic properties for the III-V systems. The total vapor pressures of arsenic or phosphorus at melting point of GaAs, InAs, GaP and InP were determined as 101, 10.1, 1510 and 253 kPa, respectively, at the corresponding melting points of 1509, 1211, 1739 and. 1336K , These diagrams are applied to the analysis of the horizontal Bridgman method and the liquid phase epitaxial growth technique. On the other hand, the analysis of the equilibrium state of the. chloride-CVD process was carried out using the data of the Gibbs energy of the compounds obtained by· authors.IntroductionThe group III-V compound semiconductors ate important materials used in optoelectronic liquid high speed electronic device. The crystal growth of the III-V compounds can involve processes that require contact between the solid, liquid and vapour phases at near equilibrium condition. Examples of processes that involve contact between the solid, liquid and vapour phases include bulk crystal growth such as the horizontal Bridgman and the liquid encapsulated Czochralski method and liquid epitaxy, and between the solid and vapor include chemical vapour deposition and molecular beam epitaxy. Therefore, the knowledge of the phase diagram and thermodynamic properties for the III-V binary alloys is essential for the analyses of crystal growth techniques of III-V compounds.For these reasons, a series of different · types calorimetric measurements had been carried out: (1) The heat contents of alloys for the Ga-As, In-As, Ga-P and In-P systems by a drop calorimeter [1;2,3]; (2) the heats of formation of the GaAs, InAs, GaP and InP compounds by a twin solution calorimeter [4]; and (3) the standard entropy of these compounds by an adiabatic calorimeter [5]. Based on the third law method, the Gibbs energies of these compounds were derived from the heat capacity, standard heat of formation and standard entropy data obtained by authors. Integral molar thermodynamic quantities of the liquid III-V .alloys were also determined from combining the heat contents of alloys with standard heat of formation and standard entropy data of the compounds· by applying the thermodynamic analysis method developed by Oelsen [6]. In the present study, the thermodynamic calculations for the crystal growth processes of the III-V compound were carried out using newly experimental data of the phase diagram and thermodynamic .properties measured by authors"

Jan 1, 2000

By Harrison Hodge

In the Bayer process for alumina production, between 2–35% Al2O3 is lost with bauxite residue due primarily to incomplete dissolution of aluminiumbearing minerals during caustic leaching or the precipitation of sodium alumino-silicate solids. The recovery of sodium and aluminium from the residue, and particularly from the contained sodium alumino-silicates, is becoming an increasingly critical issue from both an environmental and economic standpoint. Lime-soda residue sintering followed by selective leaching has been proposed as a method to recover sodium and alumina. The factors influencing the sintering mechanisms and kinetics, and the subsequent leaching have not been well described to date. In this study, the physical and chemical changes taking place during isothermal sintering of bauxite residue in air, particularly at short reaction times are investigated using scanning electron microscope (SEM) and X-ray diffraction (XRD). The impacts of these changes on the recovery of valuable materials are reported.

By M. Barkhudarov

The results are presented of research aimed at validation and development of a general purpose CFD code FLOW-3D. FLOW-3D is a commercial code developed by FLOW SCIENCE, INC. A number of physical modeling experiments involving the filling of cavities of different geometries with coloured water have been performed in order to compare the measurements with the results of computer simulations. Other numerical calculations were also done to be compared with the known analytical solutions.

Jan 1, 1992

By Andreas Siegmund

During the decade of the nineties the conventional method of primary lead smelting (sinter machine/blast furnace) was successfully challenged by the introduction of novel direct and continuous smelting processes. In combination with a significant shift in market structure, as well as more stringent government regulations these modem technological innovations like the QSL, Kivcet, and Isa/Ausmelt processes became more than major competitors. They have proven to be economically and environmentally viable. The intensification of the metallurgical reaction by applying oxygen enriched or pure oxygen bath or flash smelting principles resulted in cost savings and a higher flexibility with respect to raw materials and additives usage. By synchronizing individual auxiliary plant sections with the smelting process a virtually waste- free production and low-emission mode of operation with nearly optimum energy exploitation is achieved. The primary lead industry will gradually substitute the sinter -blast furnace operation with novel high-energy efficient technologies in the new millennium.

Jan 1, 2003

By W. F. Ranson, R. C. Progelhof

"I. THE PROBLEM: MANUFACTURING PRODUCTIVITYThe 1985 President's Commission [I] on Industrial Competitiveness found compelling evidence of the declining economic position of the United States in world markets. The annual rate of increase in the United States productivity is approximately one-seventh that of our major trading partners over the last decade: profit levels in manufacturing investments are below those of the mid-1960's; an increasingly negative trade balance since 1971; and a sharp decline in the United States share of world trade in manufactured goods for more than two decades. A particularly dramatic example of the shifting economic balance is the fact that Japanese productivity growth has been five times greater than that of this country since 1960. In face, Japan's productivity now exceeds that of the United States in such critical industries as steel, transportation equipment, electronics and electrical machinery.American employees have experienced the competitive consequences of this nation's lagging industrial performance. Between 1980 and 1984 alone, the population of non-farm employees engaged in manufacturing dropped from 22.4% to 20.6%. This reduction in manufacturing must be arrested.Commissions RecommendationsThe comprehensive set of recommendations offered by the President's Commission recognized the nation's ""key competitive advantages"", technology and human resources, and calls for their strengthening. Particular emphasis is placed on manufacturing technology and the fact that this country does not translate research into new technologies rapidly and fully.""Perhaps the most glaring deficiency in America's technological capabilities has been our failure to devote enough attention to manufacturing or 'process' technology. It does us little good to design state-of-the-art products if within a short time our foreign competitors can manufacture them more cheaply. The United States has failed to apply its own technologies to manufacturing. Robotics automation and statistical quality control were all first developed in the United States but in recent years they have been more effectively applied elsewhere""."

Jan 1, 1988

By Christoph Czettl, Christian Storf, Gregor Kücher, Stefan Luidold

The purpose of this investigation is to provide a basis for the semidirect recycling of hard metals. The present investigation focuses on revealing the fundamental chemical kinetic aspects during cemented carbide leaching in hydrochloric acid media. The kinetic relations of cobalt binder leaching from WC-Co cemented carbide are studied using a central composite face-centered design of experiments with temperature, acid concentration, and hydrogen peroxide as variables.

Mar 1, 2017

By S. P. Mathew

The ISASMELT Lead Process is a continuous two stage process for the production of crude lead from concentrate. It is based on the use of a top entry submerged Sirosmelt lance to produce turbulent baths in which high intensity smelting or reduction reactions can occur. The process involves oxidizing the concentrates in the first stage to produce a high lead slag. This slag is tapped continuously and transferred down a launder to a second furnace where it is reduced with coal. Crude lead and discard slag are tapped continuously from this furnace through a single taphole and separated in a conventional forehearth. Process and engineering design work for a commercial scale Lead ISASKELT plant designed to produce 60000 tpa crude lead has been completed. This plant is planned to be operational in 1991.

Jan 1, 1990

By Carl C. Nesbitt

A study was conducted to examine the treatment of metal-bearing effluents by precipitating the metals as sulfides and simultaneously collecting the particles by flotation. The precipitant was hydrogen sulfide gas which was introduced into a bench-scale column cell with air. The study included experiments of various flotation reagents and column configurations in treating solutions containing dissolved copper, lead, mercury, iron, zinc and cadmium. An acidic laboratory waste from a local copper operation was used to test the column with a solution containing several metals and arsenic. Precipitates were observed to form at the gas/liquid interface when the gas mixtures were rich in H2S. Copper, mercury, lead, and cadmium were precipitated from solution as sulfides to concentrations near detection limits. The flotation of these precipitates was enhanced with small amounts of S-7151 promoter from American Cyanamide Company and Dowfroth 1263 mixed with the feed. The recovery of the precipitates in this manner produced a smaller volume slurry which was easier to dewatering than a slurry produced by conventional precipitation techniques. The low pH and high oxidation-reduction potential in the cell from H2S addition was not conducive to form precipitates of iron, zinc or arsenic. However, these ions were precipitated as sulfides by raising the pH of the column discharge.

Jan 1, 1994

By Jason Ganley, Yingjia Liu, Adam Dekich, William Tilson, Jeffrey Fergus, Dileep Kumar CJ

"Manganese cobalt spinel oxide coatings have been shown to be effective for preventing chromium volatilization from interconnect alloys, and the associated cathode poisoning, in solid oxide fuel cells. During high temperature exposure a reaction layer consisting of chromium containing spine! forms due to reaction with the chromia scale formed on the alloy. The electrical conductivity of this reaction layer is much lower than that of the coating material and thus can increase the overall area specific resistance (ASR) of the system. The approaches to reducing the ASR are to reduce the thickness and/or increase the electrical conductivity of the reaction layer, which includes both the high-chromium spinel phase and the chromia scale. In this paper the effects of transition metal dopants on the amount and properties of reaction products formed during the reaction of spine! oxide coating materials with chromia are presented.IntroductionThe high cost and difficulties involved with the processing of chromia based ceramic interconnect materials for SOFCs are driving the search for metallic interconnects [1, 2]. The reduction in the operating temperature of SOFC has allowed for the use of high chromium alloy steels for this application [3]. However, the volatilization of chromium from the chromia scale, and the associated poisoning of the cathode, remains a problem which needs to be addressed [ 4]. Though the application of manganese cobalt oxide spine! coatings on the alloy surface substantially reduces chromium poisoning of the cathode [5], the low electrical conductivity of the reaction layer formed between the chromia scale and coating affects the performance of interconnect. Incorporating transition metal ions in the reaction layer could alter the electrical characteristics and improve the performance. Copper and nickel doped manganese oxide spinels are widely used as thermistors due to their high electrical conductivity and negative temperature co-efficient of resistance characteristics [ 6, 7]. Hence doping of copper and nickel in manganese-cobalt spine! oxide composition may improve the electrical characteristics of interaction layer as well and is attempted here."

Jan 1, 2012

By James W. Evans, Dong Xu, Jr. Jones

A physical (water) model based on particle image velocimetry (PIV) has been constructed at UC Berkeley. The PIV technique enables the use of water modeling to quantitatively characterize the fluid flow behavior in the mold during the continuous casting of steel, in a whole field sense, i.e., section by section. A method to obtain e\e time-averagevelocity (TA V) vector maps was developed by averaging 40 instant aneous vectc -r plots revealing the time average features of the flow. Another benefit of TAV vector maps is the ability to compare with present mathematical models, which are mostly based on the time-average technique. Bifurcated submerged entry nozzles (SEN) with ports inclined at various angles to the horizontal were used in the modeling to study their effects on the flow inside the caster. Argon was also introduced into the model to simulate the influence of argon injection on the metal delivery from the tundish into the caster. The bubble sizes and distribution (in specific sections) of argon were characterized, at the same time, by the imaging system of the PIV. This will allow for validation of current mathematical models that were developed to simulate argon injection in casters. Comparison with results calculated by the commercial finite element package FIDAP is also presented.

Jan 1, 1998

By D. B. Dreisinger

The zinc pressure leach process developed by Sherritt Gordon, Ltd. permits the direct leaching of sulphide concentrates according to the overall reaction, ZnS +H,zS04 +402.+ZnS04+H20 +S0 The kinetics of the leach are affected by three rate controlling steps; ( l) oxygen mass transfer from the gas to the leach solution, (2) homogeneous oxidation of ferric ion to ferric ion by dissolved 011.ygen and (3) ferric ion leaching of zinc sulphide in the presence of a sulphur dispersing detergent (lignin sulphonic acid). Fundamental studies have been conducted to identify the factors that influence the kinetics of each individual rate controlling step. Oxygen mass transfer studies have been directed toward optimization of the agitator configuration for solids mixing and gas pumping from the atmosphere above the leach slurry. The rate of ferrous oxidation by molecular oxygen and the rate of zinc sulphide leaching by ferric ion have been studied over a wide range of temperature and solution compositions. The study of zinc sulphide leaching by ferric ion was supplemented by a series of interfacial tension measurements in the liquid sulphur - zinc sulphate solution system. The various kinetic studies have been summarized in terms of the importance of each rate to the performance of the process.

Jan 1, 1990

By Tao Jiang

Germanium is widely used in many fields, and the production of germanium is very important. The effects of initial sulfuric acid concentration, liquid to solid ratio and other parameters on the leaching rate of germanium and zinc from germanium-bearing zinc oxide has been studied. The occurrence and form of germanium and other elements in the leach feed and the leach residue were studied by EPMA, XRD and chemical analyses. The experiments showed that the leaching rate of germanium and zinc was 91% and 88%, respectively under optimal conditions. Wurtzite was the main limiting factor for the leaching rate of zinc while the leaching rate of germanium was limited by insoluble germanium compounds. Furthermore, it was found that some germanium was bound up in galena in the leach residue. These results may be helpful for further improving the leaching rate of germanium in germanium-bearing zinc oxide.

By Jorge Gibson, P. Chris Pistorius, Megha Jampani

Increased utilization of natural gas in blast furnace ironmaking can decrease both the cost and the carbon intensity of ironmaking, given current US natural gas prices. In this paper, three ways to utilize natural gas are compared: tuyère injection, prereduction of iron ore, and shaft injection. The basis for comparison includes coke replacement ratios, carbon intensity and furnace productivity. These were calculated using relevant mass and energy balances, a blast furnace productivity correlation based on the bosh gas flow rate, and measured and modeled prereduction kinetics. Of the natural gas utilization methods, prereduction has the highest effective coke replacement ratio (and hence the largest advantage in raw material cost), but is likely to have the highest capital requirement.

Mar 1, 2017

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Kellie Provazi

"The purpose of this paper is to study metal separation and recovery from a sample composed of a mixture of the spent household batteries main types, using liquid-liquid extraction and metals electroplating. The electrolytes preparation consisted: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution were studied the liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] with tributyl phosphate as extracting agent. After study of solvent extraction and stripping has been recover and separate the metallic ions and with electroplating was recovered the manganese, copper, nickel and cobalt in their metallic forms.IntroductionCurrently has increased the consumption of electronics devices such as mobile phones, laptops, wireless phones, comcorders, etc., especially portable devices that use batteries as a power source, and consequently has increased the disposal of such material.Increased consumption of this devices is caused by several factors including increased popularity of consumer electronics devices, has become essential of modem life. Therefore, recycling of batteries is important because its reduces the waste of raw materias and nonrenewable resouces used in manufacturing these materias and help prevent potential environmental risks associated with improper disposal of these products together with household garbage.The batteries have a very diverse composition, containing metals such as zinc, lithium, nickel, lead, mercury, cobalt, cadmium, iron, copper, manganese and rare earths. Some components may contain hazardous materials such as cadmium, mercury and lead, and can contain acids or bases.This research line is a pioneer in dealing with a single process for recycling a mixture with all batteries types, for only processes that exist in the world are based on the recycling a mixture with all types of batteries, for only processes that exist in the world are based on the recycling of one or two types of batteries [1-4]. This process necessitates the previous separation of the batteries by type."

Jan 1, 2012

By Songsong Wang

Recently, replacing Pierce-Smith converting process with the oxygen bottom-blowing continuous converting technology has become a new research focus. Based on the principle of Gibbs free energy minimization, the thermodynamic model of oxygen bottom-blowing continuous converting multiphase equilibrium system has been established. The elements distribution behavior is calculated at the same burden composition and operation parameters as the industrial production. The results show that the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in crude copper are 0.06, 0.0030, 0.070, 0.38, 0.39, 0.020, 0.017, 0.034, 0.010, respectively, and the absolute errors of the mass fraction (wt%) of Cu, Fe, S, Pb, Zn, As, Sb, Bi in slag are 0.53, 0.81, 0.020, 0.23, 2.5, 0.0048, 0.0010, 0.0030, 1.49, respectively. The calculated results agree well with the actual industrial production data, indicating that the model can be well applied in the oxygen bottom-blowing continuous converting practice.

By R. Hurman Eric

The dew-point technique of activity measurements take advantage of the volatility of a component in solution. The pressure of the volatile component over a sample is determined from observations of the temperature at which condensation of the vapor occurs. The method is applicable best when the vapor pressure of the components would differ by about two to three orders of magnitude. Experimentally, this is a closed system involving the use of evacuated and sealed transparent quartz sample probes. Furthermore reliable vapor pressure data of the volatile component is essential along with a specialized high temperature furnace capable of giving reproducible results. In this context, the vertical Dew-Point Furnace (DPF) was designed and built after elaborate trails until enough proficiency was gained for reprodueible results. Over the years the DPF was modified and improved. The DPF developed was versatile and could easily be used for activity measurements in the isopiestic mode (another method of measuring activities of a volatile component in a solution). The necessary ancillary systems; namely evacuation-flushing-evacuation followed by sealing of quartz sample probes under vacuum were also perfected over the years. As and when necessary the dew-point technique was supplemented by classical equilibration-quenching method employed on the sealed quartz sample probes to reveal necessary phase equilibrium information. The following were studied utilizing the above technique: (i) Activities in CuzS-PbS and FeS-PbS binaries and CU2S-FeS- PbS ternary at 1200°C; (ii) Activities in CuzS-SnS and FeS-SnS binaries and Cu2S-FeS-SnS ternary at 1200°C; (iii) Phase equilibria and thennodynamic in Cu-Pb-S, Fe-Pb-S, Fe-Sn-S, Cu-Sn-S and Ag-Sn-S systems. Most recently the following systems have been tackled: (i) Phase equilibria and thennodynamics in the Ag-Pb-S and Sn-Pb-S systems; and (ii) Activities in Ag2S-FeS-CuzS-PbS quaternary at 1200°C.

Jan 1, 2003

By Wiraseranee. Chompunoot, Kazuki Morita, Toru H. Okabe

"Aiming at the development of more effective recycling processes, dissolution behavior of rhodium into molten slag was investigated. Using a pure rhodium crucible and Na2O-SiO2 slag system, equilibration experiments were carried out for 18 h at 1423-1623 K under various oxygen partial pressures of 0.005-1 atm with varied slag basicity. Rhodium solubility increased with increasing oxygen potential, slag basicity, and temperature. Rhodium dissolved into slag as rhodate ion ([RhO2]-) by the endothermic reaction: Rh(s) + 3/4O2(g) + 1/2O2-(in slag) = [RhO2]-(in slag). In the dissolution reaction, the “rhodate capacity” of slag is newly-defined. The correlation between rhodate capacity and optical basicity is reported.IntroductionDue to its high chemical resistance and outstanding catalytic properties, rhodium (Rh), one of the platinum group metals (PGMs), is utilized in various applications such as catalysts, molten glass vessels and containers, and electronic devices. Owing to the rarity of Rh resources in nature, recycled Rh from scraps such as spent automobile catalytic converters is currently considered as an important source of Rh supply [1]. According to the recycling practices, Rh is currently mainly recovered from scraps along with other PGMs such as platinum (Pt) and palladium (Pd) by a dry process (e.g., smelting), a wet process (e.g., leaching and subsequent separation of PGMs from aqueous solution), or a combination of both processes [2]-[4]. Among these processes, smelting is commonly applied because PGMs can be effectively separated from a relatively large amount of various impurities coexisting in scraps. In the smelting process, Rh and other PGMs are collected in the collector metal (e.g., iron and copper), and impurities in scraps are removed into slag [4]-[6]. The process may be carried out at a temperature range of 1573-1973 K, in either an oxidizing or reducing atmosphere. Due to the high oxidation resistance at high temperatures, Rh is expected to be collected efficiently in the metal collector rather than being oxidized and forming RhOx in a molten slag. However, Rh loss into slag does occur in this process [7]."

Jan 1, 2011

By Duclerc Fernandes Parra, Ademar B. Lugão, Nilton Lincopan, Fernanda Esposito, Vijaya Rangari

Polymeric hydrogels are natural or synthetic systems, which have gained interest due to their high biocompatibility with soft tissues. These types of hydrogels have been used for wound dressing as a drug delivery system. Here in this study the polymeric hydrogels based wound healing systems were prepared using poly (N-vinyl-2-pyrrolidone) (PVP), poly (ethylene glycol) (PEG), agar and neomycin drug followed by gamma irradiation to promote crosslinking and sterilization. The influence of irradiation process with 25 kGy dose was investigated. The gel fraction and maximum swelling were estimated using physicochemical methods and found about 95% gel fraction and 1100% swelling after 8 h of immersion. Neomycin released from hydrogel was carried out by Liquid Chromatography-Mass Spectrometry method and the drug concentration remained constant for 48 h. Hydrogel/neomycin exhibited antibacterial effects against Staphylococcus aureus. With these results, it can be inferred that hydrogel/neomycin is a suitable candidate for wound dressing.

Mar 1, 2018

By Yong Hack Lee

Nonferrous smelting processes have been through a rapid transformation since the beginning of 1980. The copper smelting technology has changed from the conventional Blast Furnace process to the Flash Smelting and MIB process. In the field of lead smelting, the technology has changed from the Blast Furnace Smelting to the Direct Smelting such as QSL and KIVCET. In 1992, Onsan Refinery successfully commissioned Direct Smelting QSL technology for lead. The QSL could produce more than 160,000 ton per year of lead bullion from lead concentrate and various residues. Moreover, since the year 2000, the TSL (Top Submerged Lance) Technology utilizing the same Direct Smelting process has been successfully commissioned to treat lead concentrate as well as lead sulfate residue produced from a hydrometallurgical zinc plant. This paper presents and compares the energy flows of lead smelting processes such as a conventional process and the Direct Smelting Processes plotted on the Pb-O-S phase diagram. The oxygen potential diagram suggests how to control the oxygen potential in the fum ace. Also, it describes the recent operational experience in the TSL plant of Onsan Refinery with necessary mass balance of key elements.

Jan 1, 2003

By Federica Paglietti

In this work is presented SEX (Structural & Elemental X-Ray Instrument), the first spectrometer completely portable which make non-destructive X-ray fluorescence and diffraction analysis, in contemporary and in real time. This instrument has been realized using miniaturized detectors, the same model installed on the mission Pathfinder NASA, and X-ray microtubes. SEX allows the chemical and mineplogical characterization of all kind of solid materials and allows to make chemical stratigraphy and liquids analysis.

Jan 1, 1998