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By Rajesh S. Ransing

An intelligent tool has been developed to analyse the quality of diecast components. The influence of both design and process parameters has been studied in great detail. The tool, based on expert systems related technologies, can identify the causes for the defective castings manufactured. Design related causes such as gate position; gate area, runner design etc. as well as process related causes such as cycle time, cavity filling time and melt temperature are suggested by analysing the data on defective castings for a manufacturing campaign. This intelligent analysis is useful for both design as well as production engineers in the decision making process. All the causes for the occurrence of defects are classified into two categories. The firs category is the 'rootcauses' i.e. the causes which are related to the actual process, material and design parameters and which can be directly monitored. The second category is more abstract in nature and is classified as `metacauses'. These capture the scientific rationale implicit in the cause and defect relationships. This knowledge on causes and defects is represented in the form of a structured graph rather than by a set of rules, which, coupled with forward reasoning and heuristic search techniques results in an elegant and efficient approach. Uncertainties and the degree of relationship among causes and defects are represented by a fuzzy probabilistic model.

Jan 1, 1994

By Susumu Okabe

Top blow injection has been applied to continuous copper smelting and converting by Mitsubishi Materials Corporation since 1974. In this process, injected feeds are captured by and dispersed in the molten bath immediately and effectively, and the reaction is enhanced by the agitation of the bath. The continuous motion of the molten bath, however, may cause severe damage of furnace lining materials, if the injection is not controlled and the furnace is not designed properly. In order to suppress refractory wear, especially at the bath line, surface wave of the molten bath should be moderated. A cold model study was carried out with water bath in a cylindrical vessel and the physical model was derived which correlates the oscillation of gas jet impingement on the bath surface and the surface wave. It was found that a half of the proper frequency of the gas jet impingement coincides the proper frequency of the surface wave.

Jan 1, 1998

By Bo Björkman

Four different arsenic containing dusts from the Boliden plant, Boliden mineral AB, Sweden have been examined. A kinetic study of the As elimination was performed in a laboratory scale roasting furnace for roasting furnace ESP dust and smelting furnace ESP dust. Characterisation and thermodynamic calculations were carried out to determine the mineralogy, and the stability of compounds in the dusts studied. The characterisation methods used were chemical analysis, X-ray diffraction analysis and microprobe analysis. It was found in the experiments that a high degree of As elimination was obtained for roasting fumace ESP dust and a low degree for smelting fumace ESP dust. Derived kinetic models are given. A prediction of the As-elimation for settling furnace dust and converter ventilation dust is presented.

Jan 1, 1994

By Sergey Komarov, Manuela Diaz, Sano. Masamichi

"Mixing time, bubble behavior and absorption rate of gas injected into a liquid bath through rotary L-shaped lances have been studied by cold models with an effort to improve refining characteristics of metallurgical processes. Two kinds of the rotary lances were tested, namely the single-hole lance and the multi-hole lance. The effects of gas flow rate, bath depth and rotation speed were examined.It is found that when gas is injected through the rotary lances, the mixing intensity and the gas absorption rate are larger than that for the gas injection through stationary lances. The effect of rotation speed decreases as the bath depth and the gas flow rate increase.The multi-hole lance produces much smaller bubbles, which lead to an increase in the volumetric mass transfer coefficient by 3-4 times as compared with the single-hole lance. However, the effect of rotation speed is smaller for the multi-hole lance. The obtained results are explained in terms of the bubble coalescence and fragmentation, the rate of which depends on the departure bubble size and the power supplied to the liquid bath.IntroductionIn recent years, there has been a growing interest in the development of gas injector for metallurgical processes. The majority of the previous work was focused on modification to the injector design to improve mixing and to increase the of chemical reaction rate. These two goals can not be necessarily achieved by the same way. Bottom nozzles and stationary immersed top lances, which have been widely applied to steelmaking processes, are effective for the bath mixing, but have a limit to decrease in the bubble size. This results from a vigorous coalescence occurring between the bubbles when they rise in the molten bath as a bubble swarm.One of the ways to ensure the small bubble size and the effective bath stirring is the gas purging through rotary injectors. A number of studies have been undertaken to improve the refining characteristics by using rotary injectors. All of them are related to aluminum refining. The SNIF equipment (The Spinning Nozzle Inert Flotation) has significantly improved the quality of aluminum products at National Luxemburg Aluminum [1]. Rotary injectors made in the form of a disc have been applied to the Alcoa 622 [2] and the GBF processes [3]. A study of the gas injection by a rotary impeller has been carried out by C. Leroy and G. Pignacelt [4]. All researchers note the significant improvement in removal of sodium, calcium, hydrogen and non-metallic inclusion."

Jan 1, 1996

By Xiancong Zhao, Hao Bai, Qi Shi, Zhancheng Guo

Reducing electricity cost is important for energy intensive industries such as the iron and steel industry. With the implementation of time-of-use (TOU) electricity price, plenty of attention has been paid to the optimal management of byproduct gases. The time-of-use (TOU) electricity price is the practice of implementing different prices for different times of use. It is possible to reduce electricity cost by adjusting the amount of product gases stored or used for power generation throughout the day. In this paper, a novel mixed integer linear programming (MILP) model concerning the TOU electricity price is proposed to optimize byproduct gas use. Compared with previous models, this model considers the optimal load shift between gasholders and boilers under TOU electricity price. The case study of a steel plant demonstrates that the electricity purchase cost can be reduced by more than 30% after optimization.

Jan 1, 2016

By Veneta Groudeva

A pyritic ore containing zinc, lead and copper as? the relevant primary sulfide minerals, .as well as gold and silver finely disseminated in the sulfide matrix, was? leached in percolation columns. Each column contained 30 kg of ore crushed to minus 10 mm. Firstly, zinc and copper were efficiently leached by means of chemolithothrophic bacteria? in acidic sulfate bearing medium. Zinc was leached more rapidly than copper but the final extractions of these metals were similar (about 75% in 300 days). A part of the galena was oxidized to the. insoluble lead sulfate during the leaching. The pyr:ite was, however, relatively slightly attacked. The ore was then leached by means of FeC11 - HCl solutions both in the presence and in the absence of bacteria to solubilize the lead. The chemolithotrophic bacteria grew in media containing both chloride and sulfat~ ions and maintained a high ferric to ferrous ion ratio in the percoiating solutions. The chemical leaching was, however, more efficient since ft was possible to carry it out at higher chloride ion concentrations. About 10% of the lead was leached in this way in 90 days. Finally, the ore was leached by thiourea in the presence of a gold-oxidant (oxone) to extract the gold and silver. Over 60% of the gold and over 55% of the silver were extracted from the ore in 150 days, while. the extractions of these precious metals from an untreated ore sample were lower than 25%.

Jan 1, 1991

By Oszkar Bíró, Peter Mittag, Bernhard Aigner, Stefan Pirkeri, Philipp Glttleri

"This paper considers CFD modeling of processing and melting of small metallic particles by means of electrical heating. The particles fall continuously onto a liquid metal bath which is heated by an electric arc. After melting of the particles liquid metal is tapped.The charging behavior of the particles in the supply unit as well as in the reactor freeboard is studied by means of Euler-Euler granular simulations. The flow situation in the metal bath due to gas injection and magnetic fields is calculated by combining Navier-Stokes and Maxwell solvers. The macroscopic melting process occurring during the continuous charging of the particles is studied by kinetic laws for melting reactions. The temperature field is evaluated by balancing heat sources due to Joule's heating and heat losses due to latent heat of melting as well as convection and radiation.As a result of these simulations the fully three-dimensional flow fields of particles and gas in the atmosphere is obtained. Furthermore the flow field as well as the magnetic field in the metal bath can be studied. As a main result the three-dimensional concentration field of the still unsolved particles in the liquid metal can be evaluated.IntroductionIn this paper a metallurgical process for melting small iron particles is investigated by means of CFD-simulations. In a first process step the preheated and already mostly reduced iron particles fall continuously into the reactor through a vertical tube mounted at the lid of the furnace. In a second step the particles are melted in the liquid metal bath. Meanwhile the melt is heated by electric arcs to provide the heat needed for melting the incoming particles.In Figure I a sketch of the geometry setup considered in this paper is provided. The particles fall from a height of approximately 12 meters onto the bath surface in the center of the furnace. The melt is heated by electric arcs that are placed symmetrically around the center axis."

Jan 1, 2001

By Alex Luyima, Jaan Kers, Lifeng Zhang

"The pyrolysis of PWBs was investigated by a TG-DTA-MS furnace at 300–1173 K. The kinetics and the control of emitted gas during the pyrolysis of PWBs with and without chemical additives were studied. Moreover, the possibility of controlling the amount of toxic exhaust gases like HBr, C6H6, Br2, Cl2, HCl gas and recovering beneficial gaseous fuels like CH4 and H2 from pyrolysis process is discussed. The MS data for each PWB sample were examined as a function of temperature and particular m/z values could be associated with the mass loss steps in the TG data. The degradation of the organic material was characterized by m/z = 2, 16, 18, 28, 36, 44, 71, 78, 81, and 160. Fe2O3 was the best inhibitor of toxic HBr and C6H6 when compared to Al2O3, CaO Y-zeolite and ZSM-5. Moreover, it had no significant effect on the valuable H2 and CH4 gas evolution. This selective inhibition of toxic gases while maintaining the valuable ones make Fe2O3 the best candidate among the investigated additives in controlling gas emissions from PWB pyrolysis process.IntroductionThe electronic and electric industry is one of the world’s largest and fastest growing manufacturing sectors. As a consequence of this growth, electrical and electronic waste (e-waste), such as computers, washing machines, printers, mobile phones, television sets, stereos, radios, etc., is generated in large quantities around the world. Printed wiring boards (PWBs) are a common component of many electronic and electric systems.[1]. The rapid development and expansion of the electronics industry over the past several decades have led to a dramatic increase in the production of PWBs and a corresponding increase in the amount of waste generated from both production and disposal. The environmental impacts of the treatment and recycling of PWBs waste have become a major concern [1-2]. PWBs are particularly problematic to recycle because of the heterogeneous mix of organic material, metals, and glass fiber [1]."

Jan 1, 2012

By S. P. Jupp

A 2-D coupled thermo-mechanical model was developed to simulate hot tandem rolling of AA5056 aluminum alloy using the commercial finite element software package, ABAQUS The model was used to predict the temperature, strain rate and strain distribution in the strip at any position in the roll bite and was verified through comparisons with literature results in terms of both temperature and strain predictions at the roll bite exit. A sensitivity analysis indicated that model predictions of temperature and strain at the roll bite exit were sensitive to the friction coefficient and moderately sensitive to the heat transfer coefficient for the conditions studied. Microstructure equations taken from the literature were used to make predictions at various positions in the strip. The temperature, strain rate and strain vary dramatically through the thickness of the strip in the roll bite. The sensitivity of the microstructure predictions to these parameters was assessed and it was found that using average values of temperature and strain rate in the roll bite versus exit values significantly influenced the resulting microstructure predictions.

Jan 1, 2001

By Mark Cross, Hadi Abou-Chakra, Nicholas Christakis, Mayur K. Patel, John Baxter, Ugur Tiizful

"In recent years significant effort has been put into using continuum mechanics for the description of granular flows. Although these models are partially successful in capturing some flow characteristics, they lack essential information on material properties, which are needed to account for the interactions between different particles. Thus, they are incomplete and can not be used to describe processes such as hopper filling/emptying and pneumatic conveying, where particle-particle interactions can lead to phenomena such as segregation, degradation and agglomeration. In this paper, a 3-D unstructured finite-volume framework is presented, which employs interface tracking techniques to solve for the individual material components of the granular mixture in the bulk and thus, determine the material-air interface. Various transport processes, arising from the micro-mechanical properties of the different particle species in the granular mixture, can be obtained through kinetic theory. The transport coefficients of each of the individual species can be determined and analysed in a micro-mechanical framework and the transport process parametrised in the form of constitutive models. These models provide the continuum theory with information on the micro-mechanics.This work describes the continuum framework and the micro-mechanical parametrisations, which are used to describe the processes and interactions at the microscopic level. Numerical simulations and comparisons with experimental data are then presented for the case of binary granular mixtures and conclusions are drawn on the capability of the model to realistically predict and quantify the main characteristics of granular flows."

Jan 1, 2001

By Haydar Güneş

In this study, a hydrometallurgical process was evaluated for the recovery of Nd from a Nd-Fe-B magnet. Each leaching test was performed at the solid (weight) to liquid (volume) ratio of 1:50 and was mixed at 400 rpm at ambient temperature. The effects of 3 different acids (HCl, HNO3, and H2SO4) on the extraction of Nd were investigated and H2SO4 was found to be more effective than other acid solutions. Under the optimal conditions, pregnant leach solution was produced with H2SO4 for subsequent Nd precipitation testing. Each precipitation test was carried out using 100 mL of feed solution mixed at 600 rpm at 25°C. NaOH and H2C2O4 were used for Nd precipitation. The highest Nd was precipitated as Nd2(C2O4)3, 10H2O with C2H2O4 at 20 min.

By Rush Kramer

A bulk compositional chemical analysis often provides incomplete information to help the mineral processor when faced with the problem of removing troublesome contaminants in low concentrations. Michigan Tech has developed a unique approach for addressing this problem. A combination of Scanning Electron Microscopy (SEM). Energy Dispersive Spectroscopy (EDS). and image analysis was successfully used to characterize the species responsible for phosphorus contamination of less than .05 weight percent in iron ore. An automated routine acquired the chemical signature of each particle on a backscattered electron image. The few particles containing phosphorus were identified from the hundreds of particles examined. and the phosphate phases present were easily characterized.

Jan 1, 1991

By John L. Watson

Many metals-based industrial processes experience limitations in their operations due to an inability to effectively separate solids and liquids where partidesizes are less than 25 microns. Steel plant sludges ,generated, from the cleaning of furnace off-gases represent a typical example of processing difficulties attributable to material characteristics, and recycling or even efficient disposal of these materials is often a major problem. The use of a magnetic field to augment the traditional mechanisms of vacuum dewatering has, been demonstrated in previous work to have significant value in separating solids and 'liquids, where the solids exhibit some magnetic character. Magnetic vacuum dewatering has been used with magnetite ores and with blast furnace sludges and magnetic fields have been incorporated successfully in drum and disk vacuum filters. The research described in this paper investigates the use of magnetic seed material and flocculants to extend the application of magnetic, vacuum filtration to non-magnetic pulps. It is shown that the addition of a flocculant can enhance the capacity of drum and disk magnetic fIlters when treating materials, such as steelmaking sludges, which are only partially magnetic. In addition, the use of seed magnetite with a flocculant is shown to improve the dewatering of fine hematite pulps in a drum magnetic filter. However the use of a flocculant and seed magnetite had only limited success in improving filtration in a disk magnetic filter with a fine quartz pulp. A disadvantage of magnetic vacuum filtration with seeding appears to bean increase in cake moisture due to water entrapment in the floes resulting from agglomeration and magnetic attraction.

Jan 1, 1999

By T. Alboussiere, O. Paireau

"We have designed an experiment to simulate natural convection in a direct-chill aluminium ingot. In this experiment we induce natural convection within a hemisphere filled with liquid-metal (mercury). The device consists of a copper hemispherical bowl closed by a copper plate. The top is maintained at superheat temperature while the boundary is cooled. While the temperature measurements were found using thermocouples, the velocities were obtained using an original technical procedure that relies on MHD properties. By applying a steady local magnetic field, we measure the velocity. The distribution of temperature and velocity can be separated into a thermally stratified core bounded by thermal wall jets. These wall jets greatly influence the degree of macrosegregation in ingots.1. Natural Convection in Aluminium CastingIt is well known that the quality of the final product in aluminium casting depends on the movements within the liquid metal such as forced or thermogravitational convection. Strong buoyancy-driven flows are known to occur in the liquid metal pool of an aluminium ingot caster. These flows have a significant influence on the metallurgical structure of the ingot through the redistribution of heat, fragmented dendrites and segregated material within the pool. Macrosegregation mechanisms depend on favourable temperature and flow distributions in the sump, and these factors will determine the pattern and degree of macrosegregation. Moreover, for many years, the importance of thermally-driven natural convection in casting has been underlined (Cole & Bolling, 1965). In this way, a precise determination of the velocity and temperature fields is required in order to improve understanding of the macrosegregation mechanisms. That is precisely the aim of this paper, which provides experimental data of the flow and the temperature distributions in a natural convection experiment. We intend, with this laboratory experiment, to determine accurately the velocity field, particularly within the thermal boundary layer where the effects of the flows may have an important role in the transport of crystals."

Jan 1, 1999

By C. A. Silva

The kinetics of chlorination of titanium-bearing raw materials has been investigated. For comparison purposes pellets of controlled macro-porosity, made of analytical grade TiO2 and anatase concentrate (Brazil) , have been exposed to different combinations of gas composition - CO, CO2, C12 -, gas flowrate and temperature. A thermogravimetric technique and an adapted grain model have been used in order to assess the influence of the several experimental parameters upon the chlorination behavior.

Jan 1, 1997

By Ligang Zhang, Wen Chen, Xinghua Liu, Jialin Li, Xiaoyin Liu, Zhenhong Liao

A research-scale fluidization and magnetization roasting device was developed to evaluate a processing option that might offset the complexity and high cost of the conventional magnetization roasting process on siderite. In this study, the operating parameters of the fluidization and magnetization roasting device for siderite were evaluated through cold-flow tests and magnetization roasting tests. The reaction mechanism functions of the fluidized roasting process are revealed with kinetic studies.

Jan 1, 2015

By Takamitsu Nakasuga, Haiping Sun, Kyushu University, Katsumi Mori

"The kinetic behavior of reduction of chromite ore by liquid iron containing carbon and silicon has been investigated under various experimental conditions to clarify the reduction mechanism. It was found that the reduction rate of chromium ore by liquid Fe-C alloy was very slow. In addition, when carbon and silicon coexisted in the iron melt, silicon was found to preferentially oxidized to form silica, which favored for the fonnation of liquid slag and the rate of reduction was considerably accelerated. The similar effect was obtained by the addition of some fluxes, such as SiO2, Na2B407, CaO-SiO2, which also promoted the formation of a liquid slag and thus the reduction rate in the early stage also increased.IntroductionThe reduction of Cr2O3 is a basic reaction for production of ferro-chromium from chromite ore and for chromium recovery from the slag fonned during the decarburization period of a stainless steel-making process. The reduction of chromite ore consumes much energy and its reaction rate is not so high. Thus, in order to increase the reduction efficiency, it is strongly desired to clarify its reduction mechanism from the practical and the theoretical points of view."

Jan 1, 2000

By Mike Adams

A comprehensive pre-feasibility study has been conducted by Companhia Vale do Rio Doce CVRD) for Niquel do Vermelho nickel laterite deposit. Within this study, five integrated flowsheet options were evaluated via batch and pilot campaigns at Lakefield Oretest, over an intensive six-month period from receipt of ore to final reporting. Key technical objectives set by the client included demonstrating the technical viability of the beneficiation of several ore types, processing through integrated pressure acid leach/mixed hydroxide precipitation (PALIMI-IP) and mixed sulfide precipitation (PALIMSP) circuits, and the treatment of barren liquors to meet stringent environmental requirements. Refining of the MHP was by ammonia re-leach and solvent extraction (SX) to produce LME-grade nickel cathodes, NiCO3, NiO and CoS. LME grade nickel and cobalt was also produced by oxidation of the MSP and hydrogen reduction on the leachate. The database and data acquisition system, along with web-based reporting, enabled rapid turnaround on both daily and more comprehensive run reports, making it possible for speedy and confident decisions on operating conditions of the complex flowsheets. The high value of developing such data is emphasized and discussed as pivotal in the successful progression of laterite projects through to sustainable commercial viability. Keywords: Flowsheet, CVRD, Nickel, Piloting, Pressure, Leach, Refining.

Jan 1, 2004

Novel techniques were developed to obtain samples from and make measurements in the shaft of the flash furnace at the Kalgoorlie Nickel Smelter. The data obtained was used to validate mathematical models of the burners and the reaction shaft. Particle, gas and wall temperatures were measured along with the oxygen potential of the molten particles. Collected particles were characterised by sizing, chemical analysis and optical microscopy. The region of the shaft immediately beneath the burner where the rate of change was most rapid received special attention.

Jan 1, 1993

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.