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By Yotamu Stephen Rainford Hara

"The study focuses on the reduction mechanisms of copper, cobalt and iron during carbothermic reduction of copper-cobalt mineral sulphide concentrates in the presence of lime, in the temperature range of 1073K and 1273K. We have used three types of mineral concentrates which were derived from froth flotation from the Copperbelt region in Zambia. The reduction mechanisms were studied using thermogravimetric analysis in which selected reactions were stopped at different times for characterising the reaction mechanism using optical microscopy, XRD and SEM-EDX analyses. Using SEM-EDX analysis, we have analysed in details the stages of metallic phase formation during reduction process. Metallic cobalt and iron were embedded into copper, thereby permitting magnetic separation of the reduced metals even though copper is diamagnetic. Methods of preferential reduction of metal values were investigated by analysing the metallic phase formation.IntroductionIn conventional smelting or converting of copper sulphide minerals, metallic copper forms by giving off S02 gas on. Although in terms of overall energy balance the selective oxidation for metal production has major advantages, the process suffers from drawbacks in smelting complex concentrates containing copper, cobalt and iron sulphides minerals and these are: (i) cobalt and iron are oxidised, and consequently cobalt is lost into the slag phase. (ii) The volume of S02 gas produced is in low concentrations, which is insufficient for extracting sulphur or manufacturing sulphuric acid. The release of dilute S02 causes serious environmental pollution. The major cause for the loss of cobalt and iron into the slag, is due to that fact that the oxides of these metals are more stable than their sulphides. Since cobalt and copper are more valuable than iron, reducing conditions are required in a separate slag treatment reactor using electric arc melting for recovering the lost metal oxides from slag. This energy-intensive step makes metal making expensive.During chemical beneficiation of mineral sulphides (Cu2S, CoS, FeS) in the presence oflime (CaO), two types of equilibrium conditions may be set up either by forming CaS under reducing conditions, or by stabilizing CaS04 under oxidising conditions [l]. By comparison in the presence of carbon, CaS and metallic phases form, enabling the recovery of metals from sulphide minerals, which have been investigated by a number of authors [2-9]. During reduction of metal sulphide in the presence of lime and with carbon, it has been proven that the overall reaction le proceeds via two main steps: [5, 8, 9] (i) the anion exchange reaction between metal sulphides (MS) and CaO as shown in equation la, followed by (ii) the reduction of metal oxide (MO) via reaction lb."

Jan 1, 2013

By W. C. Hellyer

The papers in this section provide several examples of the application of Process Mineralogy to metallurgical problems. Any experienced metallurgist could cite numerous other examples when process mineralogy has, or could have, provided data of value in his understanding of metallurgical processes. The data developed by mineralogic techniques may supplement conventional chemical analyses, but cannot be replaced by assays. Mineralogic and chemical analyses each provide different types of information. In order for the process mineralogist to interpret his results in the most useful manner, it is desirable that he should have some knowledge of metallurgical processes. Conversely, the metallurgist should have some knowledge of mineralogic techniques to understand the scope and limitations. Mineralogic examinations are time-consuming and expensive. To ensure the effort is not wasted, and indeed does not generate misleading information, the utmost care must be taken at every stage of sampling and sample preparation. The mineralogist may examine microscopically or by x-ray diffraction a one-gram sample representing a flow of possibly thousands of tons per day through a concentrator. Conditions in a concentrator change continually in response to changes in feed rate, feed characteristics, grind, reagent additions, temperature, circulating loads, etc. Lengthy sampling periods are required to ensure the samples examined are representative of average conditions. The sampling program should be drawn up jointly by the metallurgist and mineralogist. Sampling points should be selected with a view to ease of sample cutting. The sampler should be instructed in the method of cutting the samples, the weight or volume of sample to be taken at each cut, the sampling frequency, and sampling period. The sampling period required depends on the scope of the investigation. For example, if a complete survey is to be made of all final and intermediate products of a flotation concentrator, samples should be cut at not more than two-hour intervals, twenty-four hours per day, for not less than one week. For a more limited investigation of one circuit or one section of a concentrator, 'the sampling frequency could be increased to every hour and the sampling period reduced to one or two days.

Jan 1, 1981

By Adam Powell, David Dussault

"Electric Field-Enhanced Smelting and Refining is a process for driving the reaction between carbon in hot metal and iron oxide in slag, for example, in a steelmaking reactor. This process involves inserting electrodes into the slag and metal phases, such that the overall reaction FeO + C -> Fe + CO is separated into two half-cell reactions: Fe2+ + 2e· -> Fe at the cathode in the slag, and C + O 2 • -> CO + 2e· at the anodic slag-metal interface. Without the electrodes, the reaction is very slow, but with electrodes, the additional surface area available to the ferrous ions for reduction accelerates the reaction even without any applied bias. When a bias is applied to the electrodes, the electric field across the slag further accelerates the overall reaction.With or without applied bias, the process is first-order in the ferrous ion concentration, and limited by ferrous ion transport to the cathode. To complicate matters, as the liquid iron is reduced at the cathode, the Mullins-Sekerka instability leads to formation of dendrite-like liquid iron fingers which grow into the slag. Because of this, the design of the cathode can have a significant effect on the overall process kinetics, and understanding of the dynamics of these fingers and of their effect on mass transfer is necessary for the intelligent design of the overall process and the cathode in particular.Toward this end, a detailed mesoscopic two-phase slag-metal model is presented here which describes multi component diffusion in the slag and fluid flow in both phases in the vicinity of the cathode. Diffusion in the slag is driven by chemical and electrical potentials. The phase boundary is modeled as a diffuse interface using a phase field approach. Because this electrochemical reaction occurs at high-temperature, the kinetics of charge transfer and adsorption through the double layer are fast relative to transport, permitting the use of simple linear reaction kinetics. This also eliminates the need to discretize the double layer, with the result that charge neutrality may be assumed everywhere in the domain. Introducing electric field dependence of the gradient potential and well height coefficients in the free energy function allows the model to capture electrocapillarity at the interface."

Jan 1, 2001

By C. I. A. John

The slag dump at ZCCM's Nkana Division contains some 16 million tomes of slag, deposited since the mid-1930's. The average cobalt grade of the slag is 0.65% with some areas as high as 3%. Current arisings of slag from Nkana Smelter also contain significant tonnages of cobalt. Intensive investigations were conducted in the past into methods of recovering cobalt from these slags, although none of the processes was developed to a commercial scale. The company is now working to develop a long-term strategy for ensuring the continuing production of cobalt at optimum levels, and the resource represented by the Nkana slags will be a major component in such a strategy. The present paper reviews the various processes which have been considered for recovering cobalt, both from the dump slag and from the current slags.

Jan 1, 1993

By Michael Meyer

In the past shredder fluff was discarded in landfills, but shrinking landfill space and the partly hazardous content of the fluff as well as its caloric value, all resulted in efforts to turn this waste problem into a an energy resource. In order to produce a fuel, the inorganic compounds have to be removed. Extensive analyses and particle size measurements were made on fluff from various shredder. For optimal separation all particles are reduced to a uniform, relatively small size. In a subsequent combined - screening and air classification - process, successful separation into organic and inorganic fractions is achieved. The inorganic fraction is treated in a heavy media or an eddy-current separator to recover the valuable metals, while the organic fraction is now suitable for thermal processing, such as fluidized bed gasification and using the resulting carbon as a chemical reagent.

Jan 1, 1995

By Shichao Zhao, Ke Xie, Qijie Zhai, Wenbin Xia, Yuanyi Guo, Changjiang Song

"This paper investigated the structure evolution and phase formation ofFe-(11,13,15wt.%)Mn alloy under near-rapid solidification conditions. It is found that the area ratio of equiaxed zone in the Fe-13Mn alloy is the largest. And the primary dendrite arm spacing of Fe-(11,13,15wt.%)Mn alloy increased clearly with increasing distance from the surface. The volume percentage of HCP phase increased with increasing manganese content in the range from 11 pct to 15pct.IntroductionThe developing trend of automobile is the energy conservation, enviromnent protection, light weight, and high security. So the material would be required to the higher strength, higher plasticity and more likely to processing of automotive steel. Fe-Mn based alloys is considered as a potential material to the third generation automobile steel for its high damping performance [1], good mechanical properties [2-3], and high young's modulus [4]. And it is important that metastable HCP phases of Fe-Mn based alloys, which attracts technological interest for theoretical and experimental research [5-6].Metastable materials have been extensively used in the area of iron steels. Among various fabrication methods for high performance materials, rapid solidification is one of most popular ways to produce advanced materials by obtaining metastable phases. The solidification of metals in metastable phases provides access to an extended range of materials properties with novel properties [7]. Thus, in this work, Fe-Mn alloy metastable materials prepared by near rapid solidification is studied."

Jan 1, 2013

By T. V. Jayaraman, Kranti Kumar, Paul Praveen J., Dibakar Das, A. R. James

"Lead free piezoelectric ceramics with high piezoelectric coefficients are in great demand for sensor and actuator applications. Synthesis and characterization study of one such lead free system, barium zirconate titanate - barium calcium titanate [xBZT-(1-x)BCT] (x = 0.5), via solgel method have been carried out. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of single phase BZT-BCT nanoparticles (<50 nm). The as-synthesized powders were calcined at 1000°C and the powders were pressed into cylindrical pellets. Solid-state sintering of the green pellets at 1550°C for 2 hrs resulted in single phase perovskite structure. Hysteresis loops were obtained which indicates the ferroelectric nature ofBZT-BCT. The bulk ceramic samples with the highest sintered density (~93%) were subjected to electrical poling and the piezoelectric properties ( d33, kp, & i:,) were measured. The structure and piezoelectric properties were investigated and correlated for the given composition of the BZT-BCT system.IntroductionPiezoelectric ceramics are widely used in various sensors and actuators and most of the piezoelectric ceramics, which are presently used, are lead based, which contains at least 60% lead (Pb) by weight. The critical disadvantage of these lead based piezoelectric ceramics is their hazardous effect related to the toxicity of lead, which poses a serious environmental concern starting from their processing to the disposal stage[l]. It is well known that a material to be a good piezoelectric it requires a morphotropic phase boundary (MPB) i.e. the composition induced phase transition between any two ferroelectric phases."

Jan 1, 2013

By Snehanshu Pal

"Concrete understanding of fluid dynamics properties inside basic oxygen furnace (LD converter) and hot-metal surface deformation due to impinging oxygen jet is important for optimization of reaction kinetics and maximization of productivity and refractory lining life. In this study various k-å turbulence models and volume of fluid (VOF) method have been used to model fluid flow and interaction of impinging oxygen jet with hot metal for an industrial scale top blown LD converter.RNG, standard and realizable k-å turbulence models are used to study velocity magnitude, stream function, turbulence intensity profiles. Turbulence kinetic energy, turbulence eddy dissipation, velocity magnitude and probable mixing time have been calculated in three locations inside the converter.The average rate of oxygen jet penetration, location of vortex formation, centre line and superficial velocity of impinging oxygen jet, probability of emulsifícation are studied by VOF method.These simulation studies provide better understanding of phenomena inside LD converterIntroductionComputational fluid dynamics (CFD) modeling in the field of basic oxygen steelmaking can improve substantially the understanding of existing processes where investigation of liquid steel flow measurement is hardly possible due to the rough ambient circumstances. In order to reasonably predict gas stirring operations and emulsifícation, mass, momentum, energy transfer and dynamic interaction among ions, atoms, molecules in the bath, detailed information on flow patterns, fluid velocities, and turbulent properties is essential. Concrete understanding of bath fluid dynamics inside basic oxygen furnace is also important for optimization of reaction kinetics inside the bath and maximization of LD converter lining life."

Jan 1, 2012

By Keith E. Forrester

This paper presents results of bench scale laboratory evaluation of a processes developed by FESI and Brookhaven National Laboratories for the extraction and recovery of Pb and other heavy metals from incinerator ash which was subsequently modified by FESI for the extraction and recovery of Pb from soils excavated from a FESI client scrap yard and battery breaking operation facility. The specific waste matrix presented within the paper is a battery acid contaminated surficial soil at 0" to 12" depth. The extraction method was found to be highly successful on the bench scale in generating a final post-extracted soil matrix which passed TCLP Pb regulatory limits and retained minimal Pb after aggressive extraction application. The paper findings at this time are brief, as a majority of the research results are currently being compiled and additional efforts are underway based upon initial screening findings.

Jan 1, 1995

By Cam T. Nhan

The potential use of coal fly ash as a construction material has been recognized for many years,. In this work, an admixture of the ash residue is investigated for use as a landfill liner. In particular, its performance as a chemical barrier to the leachate from the municipal solid waste (MSW,) is determined. The test specimens are a water compacted admixture of class F fly ash, low in calcium content, which is blended with lime dust and calcium bentonite. MSW is passed through the compacted fly ash specimens under a gravitational head. The. diffusion of elements in the leachate through this material is monitored as a function of time. The distribution profiles of the retained elements in the compacted admixture provide prediction of the long term performance of the compacted admixture directly affect the leachate diffusion rate, hence, the mobilities of the retained elements.

Jan 1, 1992

By T. C. Tseng

Austenitization is a critical stage in heat treatment of steels. The available kinetic data in reference to various initial microstructures are very limited, particularly at high heating rates. In this study, integrated experimental and computational approaches have been conducted to quantify the progress of austenitization and the attained microstructure. In particular, the study is concentrated on cementite and carbide dissolution in two steel grades. Various computational methods are developed to facilitate the study: (l) an algorithm for direct determination of kinetics data as well as progress of transformation from high-rate dilatometer tests; and (2) a suite of mesoscale computational models for particle dissolution, elements diffusion, mechanics, thermodynamic and the resulting kinetics of transfonnation. Critical exprimentation is carried out using advanced techniques in microstructure characterization, chemical analysis, and Gleeble thermal-mechanical simulator on specimens of well-controlled initial microstructures. Keynotes: Cementite, Carbite, Dissolution, Steels, Austenitization

Jan 1, 2003

By J. Michael Canty

Over 25 years of US research in Mineral Recovery from Geothermal Solutions have lead to few commercial applications. With the World Bank program in Kamchatka, Russia in September 2005 a step was taken to vitalize and coordinate the many efforts to advance economic mineral recovery systems worldwide. The US Department of Energy is helping to spur on the interest and research needed to realize the many benefits of extracting minerals from geothermal solutions. The excitement of recovery of minerals from geothermal brines has many positive angles. The economics of certain geothermal site is improved if a revenue is arrived from a sellable commodity with the geothermal power. The use of cleaner geothermal brines also improves the capable use of the brine before reinjection. We will review the history of Geothermal in the USA and the opportunities for recovery of different minerals and the markets for them.

Jan 1, 2006

By Heikki Jalkanen

Oxygen converting of hot metal (LD/BOF) is contemplated as an object of simulation. Oxygen converting is a highly complex thermo-chemical process comprising a series of matter and energy transformation and transportation steps that makes the simulation very challenging. The basic principles of CONSIM 5 oxygen converter simulator are presented. Simulator is a comprehensive combination of a physical model with several empirical submodels describing all properties and processes that affect the final result of a converter blow, final mass and composition of steel, slag, dust and converter gas as well as the end temperature of steel. CONSIM simulator is used for simulation of series of high and low carbon steel blows. Simulated steel temperatures, oxygen consumption, blow time and iron oxide content of slag are compared with measured values. Problems of simulation and requirements for quantitative simulation of oxygen converter process are discussed.

Jan 1, 2006

By Hai-Xing Fang, Chao Liu, Tao Zhang, Bing Xie, Hong-Yi Li, Cui Li

"Hongge Ore, a kind of vanadium-titanium magnetite ore containing high content of chromium, is valuable resource for extracting Fe, V and Cr in China. During present processing of the ore, vanadium and chromium were both concentrated in slag, leading to higher content of chromium in the vanadium slag than that of common one in Pan-Steel. Mineral phases and characteristics of spine! crystals, which influenced greatly subsequent roasting process, in the vanadium slag under different cooling conditions were investigated by using XRD and SEM/EDS. Results showed that vanadium slags containing various contents of chromium were composed of spine!, in which V and Cr were both concentrated, olivine and pyroxene. Growth rate of spine ls decreased sharply below 1350°C. The non-isothermal crystallization process could be described by modified Avrami equation and Ozawa equation. Avrami exponent and Ozawa index were calculated and growth mechanism of spine! crystals was discussed.IntroductionVanadium (V) as well as chromium (Cr) is important non-ferrous metal widely used in materials and chemical industries [1, 2]. Especially, both of them are important alloying elements for the production of high alloyed steels to achieve desired physical-chemical and mechanical properties. Vanadium-titanium magnetite ore in Panzhihua-Xichang area (China) is an important raw material for extracting vanadium. During the extracting process, vanadium is firstly reduced into hot metal and then concentrated in slag phase by blowing oxygen into the hot metal in converter [3]. This kind of slag containing 5~20 wt% V20 3 are usually roasted with sodium or calcium salts and then leached to obtain vanadium containing solution and final products. Current vanadium slag obtained from normal vanadium-titanium magnetite ore contains low content of Cr20 3 and chromium extraction is thus ignored. However, chromium content in the vanadium slag would be increased intensively when the Hongge Ore used, which is also important vanadium titanium magnetite in Panzhihua-Xichang area containing 0.2~0.8 wt% Cr203. Therefore, this kind of vanadium slag with high content of chromium would also be important sources for vanadium and chromium extraction. According to previous work [4], both vanadium and chromium could be extracted from vanadium slag with high content of chromium by salt roasting and leaching, which is illustrated in Fig.1."

Jan 1, 2013

By Tzu-Chien Lin, Jack Tsai, Ming-Yu Lin, Der-Ray Huang, Jiin-Sen Chen, Jing-Xuan Lin

"In this paper, some DVD-R discs have been selected for long time light exposure test and high temperature and humidity test. Generally, recordable media under long time light exposure maybe be defected seriously. If we use Jitter value 8% as a reference to determine the life time of DVD-R samples, some discs defect after 5 hours of light exposure while some discs can endure over 25 hours. Also if we use reflectivity 45% to determine the life time, some discs defect after 30 hours light exposure while some discs can endure over 40 hours. From our results, the good samples show good characteristics of PI error. The absorption spectrum of recordable media is a good reference to justify the quality of dye media. These results can be used to estimate the life time of recordable discs.IntroductionIn general, the life time of DVD-R with a layer of organic dye recording layer is required for preservation in decades. In addition to optical characteristics and thermal properties, we still need to consider the stability of the dye in recording media. The presentation of the color on organic dye is not only related to the material's property but also related to the light exposure. In this study, we focus on the absorption characteristics and reflectivity of organic dye in optical recording layer after light exposure. The optical properties of discs depend on the functional groups and molecular structure [1]. According to ""DVD Specifications for Recordable Disc (DVD- R)"", the reflectivity should higher than 40%. From measured reflectivity, we can confirm that the important issue is whether dye be affected by light exposure or not. Because each specific functional group absorbs the specific spectrum, we can check the characteristics of functional groups from their UV/Visible Spectra. We also use High-performance liquid chromatography (HPLC) to detect the different components of dye on the recording layer [2]. The jitter value test is to test the error cause by digital signal of recording media. If we use jitter value 8% as a reference to determine the life time of DVD-R samples, the purpose of this study is to investigate the jitter values of recording media after high light exposure and high temperature/humidity test. The results of these test will be helpful for the development of long-life optical storage media."

Jan 1, 2012

By Robert Fritzsch, Ragnhild E. Aune, Mark William Kennedy, Behzad Mirzaei

"The quantitative particle concentration can give important information about the cleanliness of melts for quality control in primary and secondary production of aluminum. Manual quantification of the particle concentration is normally a time consuming process and human control can bias the acquired images and particle count.The present paper explains the automated image-processing steps for the quantification of SiC-particles, with equivalent diameters from 2 to 25 µm, in solidified A356. A total of 700 micrographs, acquired with a standard white light microscope with 10 x magnification, were analyzed. The applied software (Image Pro-Plus 7.0 from MediaCybemetics®) allows for programming of macros which in tum provides the user with a higher degree of control. The automated results are compared with the results obtained by manually counting the particles in the same micrographs. The impact of the automated results on the estimated filtration efficiency was established to be only -3%.IntroductionInclusions are both indigenous and exogenous particulates that are present in commercial metals such as aluminum. If large individual or large numbers of inclusions are present, they can have a significant negative impact on the appearance, mechanical and chemical behavior of products produced from the metal. Aluminum is known to contain large numbers of inclusions: =50 µm in size, e.g. typically <l ppm by volume or <100,000 inclusions of>20 µm per kg of metal as detectable using a Liquid Metal Cleanliness Analyzer, LiMCA [1]. Depending on the final application of the aluminum, inclusions can render the metal 'not fit for purpose', and result in serious economic consequences to metal producers.It is not surprising that the aluminum industry has developed a number of treatment processes to improve metal cleanliness, given the large number of high value products whose quality can be adversely affected by inclusions. CFFs are the most commonly applied filtration process and have been used to filter >50% of the world production of aluminum since the 1990's [2].Inclusions in aluminum may be particles, bifilms [3] or clusters of: oxides (Al2O3 , SiO2), spinels (MgO· Al2O3), carbides (SiC, Al4C3), nitrides (AlN), borides (TiB2), sulfides, phosphides and intermetallics [ 4]."

Jan 1, 2013

By D. F. Liub, Z. Y. Liu, W. Y. Xue, Y. F. Shenb, Y. D. Wang

"The microstructure characteristics and deformation behavior of ultrafme grained (UFO) 304SS fabricated by accumulative rolling and armealing have been investigated by means of tensile tests, electron-backscatter-diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The volume fraction of martensite phase decreases with increasing armealing temperature. In the grain sizes ranging from 300 nm to 10 µm, the strength held Hall-Petch relationship. The sample with an average grain size of 300 nm exhibited extra high yield strength of 1700 MPa and a tensile strength of 1780 MPa, while the elongation retains 12%. The limited uniform elongation in the UFO materials could be explained in terms of plastic instability. Very interestingly, for the bulk material with an average grain size of 1.200 µm, the high yield strength and uniform elongation were simultaneously achieved to be as 1000 MPa and 18%, respectively.IntroductionUltra-high strengths have been achieved in elemental metals by employing heavy plastic deformation, or by creating ultra-fine-grained (UFO) structure. Here UFO materials are defined as polycrystalline solids with property-controlling microstructural features below the 1 µm level. Typical processing routes include severe plastic deformation (SPD) [1, 2], which decomposes the grains through dislocation accumulation and reorganization (polygonization). Several different kinds of SPD process for bulk materials are typically as equal-charmel angular pressing (ECAP) [3], high-pressure torsion (HPT) [4] and accumulative roll-bonding (ARB) [5]. One of the main motivations for such a push for the very small grain sizes stems from the expectation of unprecedented mechanical strength, as predicted by the well-known Hall-Petch relationship that projects a continuous rise of strength with decreasing grain size [6]. However, these ultra-high strength metals no longer have the high ductility typical of their conventional coarse-grained counterparts, because the undesirable inhomogeneous deformation on the microstructure level can lead to the early onset of failure, severely limiting the useful ductility [2]. Recently, the interesting strategies have been performed to increasing simultaneously the ductility and strength ofUFG pure copper and nanostructured alloys by Zhao et al [7, 8]. In a pure copper, a high ductility has been achieved without sacrificing strength by introducing a high density of pre-existing twins and a large fraction of high-angle grain boundaries. Their encouraging results trigger our motivation to obtain high strength and ductility from the commercially bulk material."

Jan 1, 2013

By Riyad N. Ahmad-Bita, Shadia J. Ikhmayies

"SnO2:F/CdS:In structures were prepared by the spray pyrolysis technique on glass substrates at a substrate temperature Ts = 450°C. NH4F and HF were both tried as the sources of fluorine in the precursor solution of SnO2:F. A comparison between the properties of structures obtained by using the two doping compounds was performed. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmittance measurements were used to characterize the films. The structures prepared by using HF as a fluorine source were found to have more ordered crystal growth, larger grain size and sharper absorption edge. From the inspection of the first derivative of the absorbance it is expected that more interdiffusion on the SnO2:F/CdS:In interface takes place in the structures made by using HF. These results confirm that these films are better as forecontacts for CdS/CdTe solar cells.IntroductionThin film CdS/CdTe solar cells built in the superstrate geometry rely on transparent conducting oxides (TCOs) to make the front contact The investigation of combined CdS-TCO films has recently been developed owing to the great interest of better understanding the effect of these bilayers on the absorbers [1]. Usually SnO2 is utilized as a front contact for these solar cells. Optimizing the properties of the SnO2/CdS structures is an important step on the way to get high performance CdS/CdTe solar cells.There are different methods to prepare SnOz thin films, such as reactive sputtering [2], evaporation [3], chemical vapour deposition [3, 4], dip coating [5] and spray pyrolysis [6-9]. At the same time CdS thin films can be prepared by different techniques such as chemical bath deposition [10], thermal evaporation [11], screen printing [12] and spray pyrolysis [7, 13]. However, the spray pyrolysis technique is a very low cost and simple technique that enables intentional doping and getting large area and uniform thin films [14]. For these reasons it is choused to prepare SnOz and CdS thin films in this work. To improve the properties of these compound semiconductors, SnOz was doped with fluorine and CdS was doped with indium where such doping is well known for these compounds."

Jan 1, 2012

By M. Patel, A. W. Piper, R. A. Forsdick

"Lead bullion is refined in kettles to remove the contained impurities such as copper, antimony, silver and bismuth. These impurities are removed sequentially by the addition of one, or more, reagents to the bath. Impurity elements react selectively with the reagents to form a dross layer on the surface that is subsequently removed for further processing. Mixing the lead bath using specific impeller designs, which form a vortex to ensure that good contact takes place, carries out the reactions. It is important that the mixing is controlled to achieve the optimum bath conditions and hence good dross grades.This paper presents initial modelling work on the kettle refining process using both physical modelling (Water Models) and mathematical modelling (Computational Fluid Dynamics - CFD). Comparisons between measured plant data and simulation results are given.IntroductionThe refining of lead bullion takes place in hemispherical kettles of varying sizes. It is normal practice to remove the impurity elements sequentially, by the addition of reagents, which selectively react with the impurity element. The impurity element forms a dross layer on the surface, which can be removed for subsequent processing at the end of the reaction period.All the refining stages in the production of lead and lead alloys involve mixing the lead bath, although different conditions are required for each stage. At Britannia Refined Metals mixing is achieved using either 3 or 4 angled or flat blade impellers, which generate a vortex in the central region of the kettle. However, throughout the industry a wide range of mixer types are used which are all trying to achieve the same result."

Jan 1, 1999

By Zhang Huaiwei, Shi Xiaoyan, Li Xinlin, Sun Fei, Hong Xin

"The control of the slag properties has become very essential in improving the separation between the slag and the matte in the copper slag cleaning process. The goal of the present work is to characterize the copper converting slag through chemical analysis (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy detection (EDS) and thermal analysis (DSC). The majority of the identified elements were Fe, Cu, Si and 0. The XRD has presented compounds such as Fe2Si04, Si02, CuFe204, Fe304, and Cu. The main existence of copper element was the metallic copper due to the entrainment loss. Slight amounts of copper were existed as the CuFe204 in the slag. The density, viscosity, electric conductivity and the thermodynamic property of the molten copper converting slag were also investigated in the study.IntroductionCopper slag, which is produced during pyrometallurgical production of copper from ores, contains materials like iron, alumina, calcium oxide, silica etc. For every tonne of metal production about 2.2 ton of slag is generated [l]. The slags of copper converting process contain about 5% of copper and about 20% magnetite. The copper are present in the slags either as physically entrapped or in chemically dissolved [2-3]. The traditional slag cleaning method is electric furnace process including two steps, intensive slag reduction and quiet sedimentation. Although the process is suitable for the various copper slags, it is also with the higher energy consumption [ 4-7]. The slag characterization studies are the fundamental step in the definition of an appropriate recycling process for saving the energy consumption."

Jan 1, 2013