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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 Gudrun A. Saevarsdotti

For decades tile aluminium industry has been practicing gas treatment of aluminium melts. This treatment is of great importance because of its influence on 'impurity" and inclusion removal from the melt. The gas-melt interaction is greatly influenced by the gas composition, melt temperature etc. This paper gives an overview of the interaction between argon-chlorine gas mixtures and the aluminium melt. It covers the thermodynamics of the reaction between the chlorine and a number of different elements commonly found in liquid aluminium, and discusses the behaviour of reaction products in the melt. The paper reports an experimental study of the behaviour of the chlorine-molten aluminium interface, using sodium contaminated aluminium melt with and without the addition of grain refiner.

Jan 1, 1996

By P. J. Uggowitzer, H. Kaufmann

"New Rheocasting is a novel route of semi-solid casting, in which the globular semi-solid precursor material is produced by controlled cooling of only slightly superheated melts in conventional steel crucibles. The resulting semi-solid slugs are placed into the sleeve of a vertical Squeeze Casting Machine and then filled into steel dies. Solidification occurs under hydraulic pressures up to 100 MPa Due to the reduced cost of precursor material, reduced investment cost and easier recycling, the New Rheocasting process offers cost reductions of up to 25% over conventional semi-solid casting · routes. The New Rheocast products are pore free, pressure tight, weldable and heat treatable castings.In the present work the New Rheocasting Process is introduced and the influence of heat treatment on mechanical properties of the New Rheocast alloy A356 is discussed.The alloy A356 is cast under ideal New Rheocasting conditions into a step die on an UBE HVSC 350 Squeeze Casting machine. As-east, TS and T6 heat treatment conditions with variations in solutionizing and aging time/temperature parameters are applied and the samples are tested by tensile testing. Alternatively, the same heat treatment conditions are applied to conventional Squeeze Casting parts and compared with New Rheocasting.Questions of potential cost savings due to modified heat treatment conditions are also addressed in this paper."

Jan 1, 2000

By W. G. Davenport

This chapter shows how flash furnace industrial oxygen and oil requirements are affected by different: (a) product temperatures (b) conductive, convective and radiative heat losses (c) electrical energy inputs (d) hydrocarbon fuels. The calculations of the chapter are all for production of 65% Cu matte from pure CuFeS2 concentrate. Blast temperature is? 298 K throughout.

Jan 1, 2001

By Garry W. Warren

The brass foundry industry produces a significant amount of waste sand containing Cu, Zn and Pb which is often classified as a hazardous waste due to Pb content. The potential application of a hydrometallurgical process to treat the sand by extracting metal values and thus detoxifying the material has been investigated. The process involves leaching of metal values followed by cementation. The emphasis of this investigation was on the leaching step, although some preliminary cementation experiments have been performed. In order for any alternative treatment scheme to be successful, the smaller size fractions of the sand must be addressed. Experiments have been performed on five individual size fractions using various lixiviants HCI, acetic acid and HCI/NaCI. Cu extraction was found to be slower than either Zn or Pb. Results obtained in this investigation indicate that copper is present in two forms, an oxide form which dissolves rapidly and is insensitive to the level of oxygen, and a less soluble form, probably metallic which dissolves more slowly and requires an oxidizing agent. The presence or absence of oxygen had no influence on the rate of Zn dissolution indicating that zinc is present mostly in oxide form. Toxicity Characteristic Leaching Procedure (TCLP) tests showed that residues could be produced which meet the toxicity limit for lead. Preliminary cementation experiments have also demonstrated the feasibility of Cu and Pb recovery.

Jan 1, 1991

By J. N. Hartley

Samples of ash from the May 18, 1980, eruption of Mt. St. Helens Were collected from several locations in eastern Washington and Montana. The optical microscope and the combined scanning electron microscope with energy dispersive x-ray microprobe were used to determine the composition and mineralogical characteristics of the samples. In addition, a quantitative image analyzer was used to examine the particle size distribution, and x-ray diffraction was used to identify major minerals. Both polished sections and ultra thin sections (less than 5 ~m in thickness) were prepared to study the mineralogical characteristics. The use of ultra thin sections provided access to microstructural detail. Mineralogically, the samples ranged from almost totally glassy to almost totally crystalline. Crystal-line samples were dominated by plagioclase feldspar (andesine) and ortho-pyroxene (hypersthene) with smaller amounts of titaniferous magnetite and hornblende. Nearly all the samples contained from less than 1 to 3 wt% free crystalline silica (quartz, trydimite, or cristobalite).

Jan 1, 1981

By Yuanbo Zhang, Zhixiong You, Daoxian Duan, Guanghui Li, Tao Jiang, Xiaohui Fan

"Presently, high-grade manganese oxide ores are usually utilized by a coal-based reduction roasting process. However, there were some obvious drawbacks, including serious environmental pollution, high energy consumption, etc. The reduction temperature is relatively high (850-900 °C). In this study, a kind of biomass, pine black charcoal, was used as a reductant to reduce low-grade manganese oxide ores. Under the optimal conditions of reduction temperature of 600~650 °C, roasting time of 30~45 min and ratio of ore to reductant 5:1, the leaching efficiency of manganese reached more than 98%. Compared with the traditional coal-based reduction process, the reduction temperature is reduced by 250-300 °C.IntroductionManganese plays a very important strategic role in the national economy, and it is widely used not only in the metallurgical industry, but also in the light industry, chemical industry, medicine, agriculture, etc [1]. The average grade of manganese ores in China is evenly about 21%, which belongs to typical low-grade manganese ores [2]. Therefore, large quantity of high-grade manganese ores is required to import in order to meet the rapid development of Chinese manganese industry. As reported, the conventional treatment of reduction roasting has been widely applied for processing manganese oxide ores, in which coals or reducing gases (CO, H2 or CHi) were usually used as reducers [3]. However, there were some insuperable problems, such as high energy consumption, poor operating conditions, serious environmental pollution, etc [ 4-9]."

Jan 1, 2013

By R. J. Chesher, J. C. Anzalone, T. F. Krusmark

The BHP Copper Refinery at San Manuel, AZ employs conventional electro-refining technology, plating at a current density of 335 A/m2 on six kilogram copper starter sheets. In 1995, a combination of variable anode chemistries and increasing current density in the tankhouse created periods of increased bismuth in cathode. Bismuth in electrolyte was minimized by bleeding electrolyte to the nearby BHP leaching facility. However, the expected drop in cathode bismuth was not achieved. Investigations indicated that starter sheets contained a significant concentration of bismuth. The bismuth was found to occur in combination with antimony on the surface of the sheet adjacent to the mother blank. Studies were conducted to determine the mechanism by which Group VB elements are incorporated into the starte sheets. Operational practices were introduced to minimize bismuth in starter sheets and improve cathode quality.

Jan 1, 1997

By J. D. Ecuyer, L&apos

he microstructure of galvanneal coatings formed on extra low carbon and interstitial free steel substrates has been characterized using electron microscopy (TEM and SEM) and x-ray diffraction. The coatings are found to consist of a mixture of gamma, delta and zeta phases, of which delta is the main constituent. The amounts of each phase influences the powdering resistance of the coating which was evaluated using reverse Olsen testing and 60" bending. For the three heat input conditions considered, IF coatings were always found to contain a significant amount of gamma and only those which retained zeta phase on the surface exhibited a satisfactory powdering resistance. In much the same way, ELC coatings with relatively thick gamma layers performed satisfactorily only when some zeta was retained. It was also found, however, that coatings with minimal zeta and gamma had an excellent powdering resistance. The latter coatings were produced under galvannealing conditions of lower relative heat input. These results indicate that in addition to the zinc bath composition, coating weight and galvanneal thermal cycle, the base steel chemistry also has an effect on the coating microstructure. Knowledge and control of all aspects of galvannealing is therefore essential to consistently produce acceptable coatings.

Jan 1, 1992

By Jiang Fan, Wang Haigang

"The three-dimensional complex multiphase turbulent flow in U-beam separators was simulated using the Reynolds stress equation models (RSM). To account for the effect of the stochastic characteristic of the instantaneous gas velocity on the particles, the improved Lagrangian stochastic model based on the Reynolds stress model for gas phase was adopted, which attributed to the successful prediction of the turbulence anisotropy and particle crossing trajectories effects. The interaction between the particles was also considered using the HardSphere model. To treat the particle-wall collision, the influence of the roughness of the wall on the motion of the solid particles was taken into consideration by imposing random collision angles. The result from this study not only shows the dynamic characteristics of the multiphase flow- in the separators, but also gives the relationship among the efficiency, structure and pressure losses of the separator.IntroductionCirculating fluidized bed (CFB) combustion is one of the most promising clean coal techniques. A main feature of CFB boilers is the un-delayed recycle of solid, coal and sorbant particulate, in an external loop. Separator, which is required to separate the solid particle from the flue-gas leaving the reactor of CFB, plays an importance role in the external solids recycle loop. It affects the combustion of CFB system greatly. Presently cyclone is the most commonly used as separators for CFB system and other chemical industrial processes. It provides high level of separation for CFB system for fine particles. However it suffers from some inherent disadvantages. It's volume and size is huge. Moreover, it is difficult to design and install when the CFB workload rises. The application of U-beam separators instead of hot cyclone separators in CFB boilers has many advantages. Publications indicate proposals or successful use of Ubeam separators in Swedenr11, USA 21, Russia r3land China [4]• But it is not possible to find results in the literature of detailed investigations of this new. type of separators or recommendations on the choice and calculation of an optimal design. For this reason, numerical simulation for the three-dimensional gas-particle two-phase flows with several rows of vertical U-beam elements, local in the chess order and blocking a way of outgoing from a CFB boilers dusted gases was carried out in this study."

Jan 1, 2004

By Jacques J. Eksteen

Any effort to improve the metallurgical control of industrial furnaces employed in the primary extraction of high carbon ferroalloys are bound to fail unless the variability of the melt is not fully accounted for. A number of sampling campaigns were performed on both 3phase AC submerged arc and single phase DC open arc furnaces at different smelter sites in South Africa where High Carbon Ferrochrome is produced. It was found that the heterogeneity between multiple samples during a single taps were much higher that for heterogeneity found within a sample. Moreover, this heterogeneity (as quantified by the relative standard deviation per tap) varied with the operating conditions of the furnace, the element monitored and the type of furnace. A relationship was found between the relative standard deviation of certain elements and the degree of subcooling of the melt.

Jan 1, 2006

By Jan Pan, Deqing Zhu, Xianlin Zhou, Yanhong Luo, Zixing Xue

"Magnetic roasting process, aiming at obtaining magnetite concentrate, is the principle method of exploiting siderite as a raw material in iron and steel industry. Study on preparing DRI from siderite through coal based reduction technology is sporadic. To make the process of how siderite is reduced to iron clear, roasted ore reduced from siderite by lignite under different time periods were analyzed. The results indicated that: at the temperature of 1050°C, siderite was rapidly decomposed into magnetite, and further reduced as Fe30r?FeO?Fe, the later step was slower than the previous one. A fracture of particles was found during the process of thermal decomposition and the reduction of newly formed magnetite. As the reduction proceeded, metallization rate of products increased, and the iron grain grew along with time.IntroductionWith the rapid development of economy, China demands more and more iron ores for the iron and steel industry. China has rich iron ore resources, but 97% of them are below 30% in iron grade, many are refractory and unutilized [1], therefore large quantities of imported iron ores are in a desperate need. China imported 686 million tons of iron ore in 2011 (data from the China Customs), accounting for nearly 60% of the total consumption. To guarantee the healthy development of iron and steel industry, domestic refractory iron ores have to be utilized both economically and environmentally."

Jan 1, 2013

By J. T. I. Poijärvi

The smelter off-gas cleaning and the weak acid treatment at Outokumpu Harjavalta Metals Oy are presented and described in this paper. The smelter consists of the copper and nickel smelters and the acid plant of three separate acid plants two of which are double contact and one single plant and of one liquid sulphur dioxide plant. The preliminary cooling and flue dust separation of the smelter off-gases from the copper and nickel flash smelting furnaces and converters in the waste heat boilers and in the hot electrostatic precipitators are described. The final cooling and cleaning of the gases in the scrubbers at the sulphuric acid plant and the treatment of the weak acid in the vacuum and in the submerged combustion evaporators for the removal of impurities are pre¬sented as well as the treatment of the condensates from the evaporators. The attention is paid to the generation of sulphur trioxide in the smelter off-gas and to the treatment of that in the weak acid bleed-off and to the utilization of the treated acid.

Jan 1, 1992

By R. Craig McClung

Contrary to other sulfide minerals, where recovery is principally liberation controlled, the recovery of molybdenite is more complex. It is this complexity that initiated a geometallurgical investigation of molybdenites from Bingham Canyon. The aim of this investigation was to determine the effect mineralogy and/or mineralogical attributes have on recovery. All samples were analyzed using normal mineralogical techniques. The results reveal the presence of two distinctly different types of molybdenite. These have been identified as the two polytypes of molybdenite: i.e. hexagonal (2H); and rhombohedral (3R). The 2H-polytype occurs as textbook-shaped particles in quartz-molybdenite veins that are located in the current pit bottom. The 3R-polytype occurs as disseminated, “ball”-shaped particles with a dull or frosted appearance and are concentrated along the margins of the current pit. Concerning their metallurgical behavior, each type exhibits unique metallurgical properties that are consistent with those reported in the published literature. The 2H-polytype is easily ground and kinetically “faster” floating with surface attributes that are amenable to higher rates of recovery. This results in the production of a high quality concentrate under normal operating conditions. The 3R-polytype, by comparison, is difficult to grind and kinetically “slower” floating with surface attributes that are less amenable to recovery. Therefore, in deposits with higher concentrations of the 3R-polytype, modifications to the normal operating parameters may be necessary to improve recovery. This investigation highlights the necessity for understanding the mineralogical characteristics of any economic mineral(s), as these will have a direct impact on recovery.

By Cynthia K. Belt

Improved energy efficiency has grown in importance within industry as energy costs have escalated. The analysis of trends and changes to a process is critical in making the best business decision in energy management. Frequently, energy use per day (Kilowatt-Hour or British Thermal Units) is used to track energy efficiency. Sometimes, the somewhat more complex method of energy per processed weight (Kilowatt-Hour per Metric Ton or BTU per Pound) is used to make this evaluation. Yet both methods ignore the effects due to throughput and weather. In this paper, different thermal processes and systems will be evaluated using statistical methods to highlight alternative methods to evaluate energy efficiency. Examples and potential problems will be discussed for both a single process and a collection of processes within a plant or corporation.

Jan 1, 2008

By William Brinkman, Mark Jolly, Nasim Soleimanian, Karl Dearn, Oliver Brinkman

"Glass manufacturing is a heat intensive process. There is a direct correlation between the batch distribution techniques and the furnace energy consumption, productivity, and quality of the glass manufactured. All four major segments (float, container, fibre, and specialty glasses) would benefit from using an optimised batch distribution technique where possible. Oscillating batch chargers (OBC) have been in use since the early 70s, despite their superior batch shape, coverage, and in turn positive effects on the energy consumption and productivity of the furnace they are almost exclusively used in container glass manufacturing. The OBC’s main difference compared with other charging methods is its ability to directly influence the batch initial velocity. This paper reports on results achieved in CFD models (GFM) used to study effect of the machine on the overall energy consumption in the doghouse and the melt space.IntroductionGlass manufacturing can be divided to four major segments float glass, container glass, fiberglass, and specialty glasses. The financial cost of manufacture, its impact on the environment, lack of standardisation and mounting pressure imposed by the authorities for reduction in emissions means that the industry and its suppliers are utilising CFD modelling in order to tackle these challenges. The need for high temperature to create and maintain the viscous flow, homogenisation of the glass melt, and maintenance of the process to allow continuous output of glass of the right quality are the contributors to the energy intensive activities that are involved in continuous glass manufacturing. This in turn has resulted in design of large container glass furnaces which have high energy consumption, low specific performance, and high CO2 emissions where the most efficient furnaces in the container glass sector have a specific primary energy consumption of 3.8 GJ /tonne of glass at a level of 50% cullet in the batch making even very small improvements in efficiency by operation optimisation a value adding activity [1-14].The theoretical calculated energy required to melt glass is 2 to 3 times less than the energy actually used to melt glass as a result of glass melt passing a zone 5 to 8 times before leaving the tank.[8]. This causes contamination as the result of mixing between the completely molten glass free from bubbles returning to the batch area where there is freshly molten non-homogeneous glass, still containing very large numbers of bubbles and un-molten batch. At high temperature some components are dissolved rather than melted. Given that an un-molten batch is a good thermal insulator, it can be transported a long way into the furnace, increasing the need for homogenization which also increases the glass residence time of glass melt. This is why large unbroken strings of batch should be avoided, as should an overall blanket without gaps."

Jan 1, 2014

By Susanne Pignolet-Brandom

Reflected light microscopy scanning electron microscope energy dispersive spectroscopic analysis and backscatter electron image and electron microprobe chemical analysis have been used to study lead sinter and lead blast furnace slag. These studies provide invaluable information on the phases present their intergrowths, and their chemical composition. Such information increases the understanding of the nature of pyrometallurgical processes and the behavior of minor elements during these metallurgical processes.

Jan 1, 1987

By Dan Wang, Qian Xu, Guangshi Li, Xionggang Lu, Xingli Zou, Zhongfu Zhou, Hongwei Cheng, Changyuan Lu

The preoxidation of the ore has a profound significance to the concentration, separation and purification of nickel and copper from the lean complex ore. In this paper, the natural Ni-Cu sulfide mineral samples under the elevated temperature condition in air were investigated, as well as under isothermal condition at 600 oC in air. The mineralogical characterization was studied using XRF, ICP and the Rietveld method. The oxidation behavior and the element migration of the Ni-Cu sulfide ore were studied by XRD, SEM-EDS and TG. The XRD Rietveld method was successfully developed in the phase identification and quantification of this complex ore powder sample. The oxidative intermediates (Cu/Ni-ferrite) were detected by XRD, and the process of the element migration was obviously revealed by the line scans using SEM-EDS. It is the preoxidation of this mineral that provides guidance for the extraction of valuable metals from low-grade Ni-Cu sulfide ores in the future.

Jan 1, 2015

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By Wilhelm Wendt

About five years ago we showed that it is possible to use the spectral in- formation in the light emitted by the off-gas flame of a PS converter for on-line production control. Very recently measurements have been performed using improved optical equipment and data evaluation software, resulting in both improved accuracy and the establishment of new optical process parameters. Using the optical signals the slag heats could be stopped at a predetermined Cu content of the white metal with an accuracy of +0.2% Cu m the range 74-78% Cu. A good correlation was found between the slag composition and optical data, providing a possibility for on-line monitoring of the SiO2 content of the slag. The measurements indicate the possibility of predicting the optimum end-point of the copper-making stage and having real time information on the impurity removal. Factors influencing the optical parameters, such as blowrate, Pb content, temperature etc. will be discussed.

Jan 1, 1993