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By Shaohua Ju

Siderite ore is abundant around the world, due to its inert properties of low grade, mudding when milling and low magnetic, and it is very hard to be beneficiated. Nowadays, decomposition by roasting becomes the main process for utilization of the siderite ore. The methods of energy input for roasting are normally electrical heating, coal or gas combustion. Because traditional roasting methods owns some disadvantiges, such as low energy utilization, high cost and/or large exhaust pollution, only about 10% of the siderite ores in China were used as iron concentrate. In this work, the possibility of roasting siderite ore with microwave energy is studied by both laboratory and pilot experiments. The result of laboratory experiments showed that the optimized condition is roasting for 20 min with a power density of 3 W/g, and the Fe content of the final sample obtained is about 59.12%. The pilot experiments result showed that the decomposition is thoroughly, and the main phases of the roasted material are magnetite and wustite, and the energy consumption of the roasting process is 695.8 KWh/t.

Jan 1, 2014

By Dai Yongnian

The methods of treating zinc crust and its development in the last hundred years are compared and reviewed. There are better effects from normal pressure metallurgy turned into vacuum metallurgy. The traditional methods dezinc only. But we must consider that delead on further step. From lab tests to industrial scale experiment are researched. The first step-dezinc, second-delead, crude ,metal of, zinc, lead and silver are produced, The flowsheet of treating zinc crust are simplified, material consumption reduced, work condition improved, environment protect mended. This method is pointed out that its application can be expanded.

Jan 1, 1992

By Don Ibana

Supported by the Minerals Council of Australia (MCA) through the Minerals Tertiary Education Council (MTEC), three Australian universities–Curtin University, Murdoch University and the University of Queensland–have formed the Metallurgical Education Partnership (MEP) to jointly develop and deliver an engineering design capstone unit–Metallurgical Process and Plant Design–in their respective undergraduate programs in extractive metallurgy, in order to enhance the students’ educational experience. A unique feature of the program is the close interaction of the students in all three universities and a significant involvement of industry professionals. Now in its sixth year, it is clear that this unit is achieving its objectives

Jan 1, 2014

By Youngkook Lee

The precipitation kinetics of NbC in ferrite matrix of the Nb microalloyed steel was investigated experimentally and numerically. The mole fractions of NbC precipitates formed at different isothermal temperatures were measured as a function of holding time by electrical resistivity test and were compared with both a mathematical model based on time-dependent nucleation and growth rates and the hardness. There is a good match among the calculated and measured precipitation kinetics of NbC and the hardness. The isothermal precipitation-temperature-time diagram of NbC in ferrite matrix of the Nb microalloyed steel was newly generated. Keywords: Precipitation, Carbide, Ferrite, Nucleation, Growth, etc

Jan 1, 2003

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

By A. K. Kyllo, N. B. Gray, B. N. McCurry

"Dynamic control of the formation of a solidified layer between a pipe wall and a flowing melt enables the flow rate to be adjusted in real time. This solidified layer can be generated by using a coolant on the outside of the pipe wall to remove the required heat. The coolant, and hence the solidified layer, can be controlled remotely. The dynamic behaviour of the solidified layer was investigated by both physical experiments and mathematical modelling. The mathematical model has been developed using a finite difference technique to describe conduction through the pipe wall and solidified layer. Results from the model were consistent with previous steadystate experimental results using molten lead. Experiments are currently being carried out using molten tin in a recirculating circuit with a cooling system that is instrumented for accurate computer control to validate the model. The circuit is designed for flowrates of up to 24 kg/s (86 tph) of molten tin. Steady-state and dynamic predictions were made for the current rig.Industrial SignificanceThe current method of choice for tapping slags, metals and mattes from many metallurgical furnaces is using an oxygen lance to open the taphole and using a clay plug to close it. There are, however, some significant drawbacks in this method. The heat generated by the oxygen lance erodes the refractory lining of the taphole, as well as the clay plug, and the furnace products themselves corrode the taphole. Using an oxygen lance is also a significant safety hazard to the operators as they must work in close proximity to the furnace and be subjected to a shower of sparks while opening the taphole. Also, the flowrate of material through the taphole cannot be controlled online as the diameter of the opening cannot be varied easily. This feature means that the level of product in a furnace cannot be kept constant."

Jan 1, 1999

By Olusegun J. Ilegbusi

"A two-fluid model is used to calculate flow and heat transfer characteristics of a plasma jet. This model accounts for both gradient-diffusion mixing and unmixing that may result from pressure-gradient-body-force imbalance in the system. The unmixedness is considered to be essentially a Rayleigh-Taylor kind instability. Separate transport equations are solved for the plasma and ambient gas velocities, temperatures and volume fractions. The two fluids allowed to exchange mass, momentum and energy through empirical interaction parameters. The empirical coefficients are first established by comparison of predictions with available experimental data for shear flows. The model is then applied to an Argon plasma jet ejecting into stagnant air. The predicted results show the significant build-up of unmixed air within the plasma gas, even relatively far downstream of the plasma torch. By adjusting the inlet condition, the model adequately reproduces the available experimental data on the temperature profile.IntroductionPlasma jets have important applications in materials processing, some of which include spray deposition, melting and refining, heat treatment and materials synthesis. In a typical reactor, the hot plasma stream entrains a surrounding gas and the resulting heat and mass transfer and the condition of operation of the torch, determines to a large extent, the performance of the unit. The entrainment may prevent uniform mixing and produce regions of unmixed hot/cold gases and non-uniform deposits as a result of insufficient melting of deposit in cold regions. This phenomenon may also affect chemical reaction rate in plasma systems for NOx reduction in exhaust gases.The study of plasma phenomena is often conveniently divided into three parts namely, the plasma torch, the plasma jet and analysis of the particles carried in the jet. The present work concerns processes occuring in the near-field of the plasma jet i.e. just downstream of the torch."

Jan 1, 1994

By A. Perillo

The process, realized in. the Kivcet furnace, can convert continuously lead concentrates, residues and secondary lead bearing materials into a lead bullion free of sulphur and a discardable slag. The lead recovery can be up to 99%. The long experience of about three years at Portovesme demonstrates the capability of the furnace to smelt a very. high range of lead raws without interruption of the operation. The operating costs are very competitive in comparison to the traditional technology. The work place and environment are clean and new tight regulations for the? hygiene control are met. The Kivcet furnace can be considered as consisting of three parts (reaction shaft, waste gas shaft and electro-furnace) connected with a common hearth. The technical basis of the furnace construction is the application of a number of design elements .which have mostly been used before in designs of industrial furnaces, such as open hearth furnace, refining furnace and other furnaces dealing with liquid meta1s. Refractory wear in the reaction shaft with typical pattern from watercooling soon has been stabilized and since maintained. No deformation of the furnace shell and no leakage of metal or s:l:ag through the bottom is? appeared after three years' operations.

Jan 1, 1990

By Dao Su, Ganghua Fu, Xuling Chen, Yufeng Guo, Min Gan, Tao Jiang, Xiaohui Fan

"The sinter quantity and quality of limonite in the magnetite and hematite sintering models were studied and compared. For the sintering of magnetite, the results showed that the increase of limonite improved the permeability of sinter mixture, increased the sinter quantity and quality. The sinter strength and productivity were decreased when the proportion of limonite exceeded 50%. The appropriate proportion of limonite was 40%-50%. For the sintering of hematite, the sinter quantity and quality were first maintained at the same level thereafter declined, more obviously when the proportion of limonite exceeded 40%. The amount of calcium ferrite increased whose shape changed from acicular to leaflike and block gradually with the proportion of limonite increased from 0% to 80%.IntroductionWith the fierce competition of domestic and overseas iron markets in the twenty-first century, cheap ores such as limonite are used to be sintering raw materials to cut the costs of sinter and pig iron for steel making, and boosts the competitiveness of steel companies [1, 2]. In addition, as the reserve volume of hematite of high grade is reducing year by year, the usage amount of limonite in sintering are expanding in major domestic and international sintering plant [3, 4]. Sintering can be divided into two types, majoring in concentrates and fine ores, according to the different types of raw materials. The sintering characteristics of limonite in the two types above have been studied and compared in this paper, which makes a significant sense for the research of limonite sintering properties and guidance of ore proportioning in sintering plants."

Jan 1, 2012

By I. A. Ibrahim, A. K. Ismail, A. A. I. Afifi

"Synthetic rutile for paints industry is conventionally produced by a combined smelting and leaching process. Smelting process is an energy intensive step and represents economic burden in view of the increasing energy costs. Egyptian ilmenite ore containing 40% TiO2 and 38% total Fe was thus directly leached with sulphuric acid to produce eventually synthetic rutile. The process-involves digestion of the ore with sulphuric acid whereby both TiO2 and Fe are dissolved. The solution was then treated with iron powder to convert Fe3+ to Fe2+ to avoid co-precipitation of iron during the hydrolysis step. After solid/liquid separation and clarification, Fe was crystallized as ferrous sulphate hydrate by chilling. The titanium pregnant liquor was concentrated by evaporation and then hydrolyzed to precipitate hydrated titanium dioxide which was then calcined to produce synthetic rutile containing 98.6 TiO2 and 0.58% Fe2O 3. The optimum conditions of all the processing stages were determined.IntroductionSynthetic rutile for paints, welding rods and other industries could be produced from ilmenite ore by sulfuric acid leaching process. This process is a batch process and nearly 80% of all TiO2 produced in the world is made by this process [1]. Figure l shows simple block flowsheet of the process. The process involves the following stages.Digestion: In this stage, ilmenite ore is treated with concentrated sulfuric acid where both iron and titanium are converted to their respective sulfates according to the following equations:"

Jan 1, 2000

By V. Gornitz

The Orphan mine uranium deposit, Grand Canyon, Arizona, is a cylindrical collapse-breccia pipe, 70 to 150 m in diameter and 500 m deep. Pipe fill was derived from the Supai Group, Hermit Shale, and the Coconino Sandstone. Uraninite, with Cu, Fe, Pb, Zn and Ni-Co sulfides is concentrated along the pipe boundary ring fracture (annular ring) and within the central porous sandstone matrix. There is some suggestion of vertical and lateral zonation of U with respect to Cu. Reduction of ferric oxide cement from red beds and recrystallization of carbonate, with formation of kaolinite preceded major ore deposition. Early Ni sulfides, arsenides and disseminated pyrite were followed by massive pyrite, and botryoidal uraninite, which in turn was suc-ceeded by Cu, Zn and Pb sulfides. A second, later generation of uraninite was closely intergrown with hematite and base metal sulfides. Oxidation of primary minerals may have been associated with Tertiary regional uplift. The paragenetic sequence closely resembles that of other Grand Canyon breccia pipes, except for the extensive development of the distinctive uraninite-hematite association. Mineral assemblages at the Orphan suggest possible mixing of the metal-bearing solution(s) with a more oxidized fluid, containing soluble uranyl complexes. Homogenization temperatures of fluid inclusions in calcite (GO-lIO?C) at the Orphan fall within the lower end of the range observed at other breccia pipes.

Jan 1, 1987

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 D. R. Kreuzer

The sulfide smelting industry is striving for up-scaling their operations by increasing the throughput and efficiencies of the furnaces. The physical phenomena related to refractory materials prevailing in smelters and furnaces are highly complex. The refractory materials are exposed to fairly high temperatures, thermo-mechanical stresses, penetration of pores, erosion and chemical corrosion. The application of numerical simulation tools is needed for the refractory engineering task to consider those phenomena and to evaluate the impact of operational regimes on the refractory design and finally on the integrity of the furnaces. The work discusses case studies of simulations addressing problems and questions related to the refractory design process. Practical simulation approaches which employ simplified models are introduced as the engineering process demands results in a reasonable time.

By Gong-yi Guo, Yu-li Chen

"A partially-stabilized zirconia powder was prepared by metalorganic precipitation process from technical-grade zirconium oxychloride and the effluent of an acrylic acid plant. The effluent contained low molecular weight carboxylic acids, i. e., acrylic acid and acetic acid. The· developed process is based on the selective precipitation of acrylic acid at suitable pH values by the addition of zirconium oxychloride to the effluent. The resulting precipitate is a precursor that can yield a pure, ultrafine, and partially-stabilized zirconia powder. The evolution of formation of the partially-stabilized zirconia in the present process was investigated using thermal analysis, infrared spectroscopy, and X-ray diffraction technique. Environmental, technological and cost advantages will make the present process feasible for manufacturing advanced zirconia ceramics.IntroductionIn recent years the superior mechanical, thermal, electrical and chemical properties of stabilized zirconia have become the focus of growing scientific and technological interest, and hence resulted in various structural and functional applications. The great potential of the material has given rise to numerous preparation approaches to obtain the material with the excellent properties; nevertheless, an extensive number of programmes are underway worldwide aimed at understanding and improving both the preparation and behavior of stabilized zirconia ultrafine powders. (1 – 8)."

Jan 1, 2000

By Jiayan Li, Yi Tan, Yao Liu, Yaqiong Li, Shenrui Wu

"A metallurgical grade silicon (MG-Si) refining concept process was presented. Under vacuum conditions, silicon was selectively oxidized by high purity silicon dioxide to form gaseous silicon monoxide while impurities with low vapor pressure in MG-Si were rejected in residue; Then high purity silicon was obtained from the disproportionation of condensed silicon monoxide; and by-produced silicon dioxide was recycled for the oxidation step. Thermodynamics on boron rejection during the oxidation were studied in this work. In the temperature range of 1200-1800K, the saturated vapor pressure of boron, and the Gibbs free energy changes, the equilibrium partial pressures of silicon monoxide and boron oxides of potential reactions were calculated. And the effect of boron activity in MG-Si was also discussed. The results indicated that boron in MG-Si can be rejected during the oxidation and it showed the potential for the further development of the new refining process.IntroductionAs global energy consumption growing dramatically, higher prices of energy and global warming problem have attracted more and more attention [1]. As a clean and renewable energy industry, the photovoltaic (PV) industry converts solar energy to electricity using solar cell device and has a growth rate of about 30% in recent years. It has caused a shortage of silicon feedstock due to that about 90% of solar cells are made of crystalline silicon. And high energy consumption during the production of silicon material, i.e. solar grade silicon (SoG-Si), is main obstacle for its mass production."

Jan 1, 2012

By Yasuo Kudo, Wu, Hayato Sato, Hiroshi Nakazawa, Shouming

"In order to recover copper from a waste nickel condenser powder, bioleaching experiments were carried out using Thiobacillus ferrooxidans in a shaking flask. The content of nickel and copper in the waste nickel condenser powder in this study were 8.0% and 3.5%. X ray analysis showed the peak of barium titanate. In the preliminary study using metal nickel and copper powders , the dissolutions of nickel and especially copper were accelerated with the addition of ferric iron in the bioleaching of nickel and copper powders while not in the absence of ferric iron. Ferric iron oxidizes both metals, and Thiobacillusferrooxidans oxidizes ferrous iron resulting from the oxidation of metals, whereby the dissolutions of metals proceeds. The dissolution rates of nickel and copper increased with increase in the concentration of ferric iron in the bioleaching of the waste nickel condenser powder.1. IntroductionNickel condensers rejected from manufacturing plants are crushed and landfilled. Waste nickel condensers contain nickel and copper and could be considered as nickel and copper ores. Since the capacity of landfills is diminishing, it is required to recycle metals of waste nickel condensers in order to reduce the amount of wastes landfilled. Conventionally, metals in the waste were recovered by dry metallurgy after the incineration.Nickel has been refined by solvent extraction - electrowinning method (SX-EW method). Recently the amount of copper refined by SX-EW method has increased (Takahashi, et al. 1994). This method is cleaner and consumes less energy than conventional methods. Nickel dissolved well in acid solutions, but copper is not. If copper is leached efficiently from a waste nickel condenser powder, SX-EW method will be applied to recover copper from them"

Jan 1, 2000

By H. J. Roorda

With an increasing need to obtain metals by processing complex fine intergrown ores, the use of electron-optical techniques will become more important as a tool for mineralogical studies. Electron images enable a higher spacial resolution than can be obtained by optical microscopy and thus provide a powerful and necessary aid for the examination of small grains and finely locked particles. In this paper the mineralogy of Meggen ore was investigated. Both light-optical and electron-optical techniques were used to evaluate the mill feed and products of the concentrator. Detailed examination by reflected-light microscopy to assess the comportment of galena in the complex pyritic ore was inconclusive in establishing the cause for low lead recovery of only forty percent of the ore's lead content. Electron microprobe analyses indicated that the majority of the lead lost to the tailings was accounted for by extreme fine (often smaller than one micron) and complex intergrowths of galena in pyrite. The remainder was lost as fine free galena grains.

Jan 1, 1987

By S. G. Kumar

Experimental studies on high carbon steelmaking through LD Converter - Vacuum Arc Degassing - Bottom Pouring route to produce low oxygen steels were carried out. The results indicated that it is possible to produce steel with a total oxygen content of less than 15 ppm. Thermodynamic and mass balance calculations are made on low-carbon steels that are treated by a complex deoxidation practice based on primary deoxidation of aluminum, manganese and silicon additions; followed by secondary deoxidation of vacuum degassing with simultaneous additions of aluminum. The results showed that primary deoxidation is mainly due to aluminum and the effect of carbon under reduced pressures on deoxidation of molten steel that is already killed by aluminum is negligible. The effect of process parameters on total oxygen content of steel, like carbon content, slag composition and inert gas purging, are discussed.

Jan 1, 1994

By S. Yuan

Oxygen ion conducting yttria-stabilized zirconia (YSZ) tube was used to remove oxygen from molten Cu at 1373K. Outer surface of the tube was in contact with the melt and the inner surface containing a thin layer of porous Ni-ZrO2 cermet electrode was in contact with a reducing gas. The migration of oxygen species (O2-) from the Cu melt through the YSZ tube is accompanied by an equal and opposite flux of electrons maintaining electroneutrality. Without applying an external EMF, the fluxes are maximized by short circuiting the melt with the cermet electrode. For efficient oxygen removal, the YSZ tube must be thin, contact resistances should be negligible, and the electrodes must be porous and cover the entire electrolyte surface for charge transfer. This refining process is environmentally sound, can use reducing gases such as H2, CH4 and CO without running the risk of increasing H or C content of the melt.

Jan 1, 1993

By Emmanuel N. Zevgolis

In the present work, a reduction roasting experimental study of Greek nickeliferous laterite samples with a gaseous reducing mixture ? CO:N2- is presented. The effect of parameters such as temperature, ore grain size, and composition of the reducing mixture were examined. It is deduced that the reducibility of intermediate type laterite sample, where iron appears mainly in the form of goethite (a-FeOOH), is considerably higher than that of limonitic type laterite samples, where hematite (a-Fe2O3) is the predominant iron mineral phase. The degree of reduction of the limonitic type laterite samples does not exceed 50%, while it reaches 95% in the case of the intermediate-type laterite sample under the same experimental conditions. Increasing the temperature in the range 750-900°C does not considerably favor the reduction of the limonitic type laterites, whereas decrease of ore grain size of the limonitic-type ore samples and more intense reducing conditions increase the reduction. The considerably higher specific surface area values of the intermediate laterite samples, diminishes the effect of the ore grain size and this can be regarded as the critical parameter leading to the higher reducibility of this ore.

Jan 1, 2009