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Silver has the highest electrical conductivity of all metals and consequently this property is an attractive feature which makes it a leading candidate for use in electronic devices. The research conducted was focused primarily on the development of a process for obtaining a deposited silver-coating onto alumina, for applications related to electrical-conducting devices and, ancillarily, catalysts. Alumina balls and plane substrates were utilized for the investigation. The coating process employed an aqueous arnmoniacal silver-nitrate electrolytes with a formaldehyde solution as the reductant. Modifying additives - an activator which would be expected to promote good deposition-characteristics onto the (dielectric) substrate and an inhibitor which would obviate homogeneous reduction (precipitation) of silver was observed when the activator-containing silver-electrolyte reductant constituents were combined. However, the silver-electrolyte/reductant system with inhibitor could be employed (at 80°C) to achieve a viable (subject to future research optimization) coating on alumina. The influence of the processing temperature on the deposition process was delineated during the course of the research. The morphology of the deposited-silver on the alumina balls was assessed by SEM imaging. A tape-peel test was employed, with the plane substrates, to semi-quantitatively characterize the adhesion to the alumina.

Jan 1, 1998

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. In this work, thc potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (DW). Seven taxa are of Alyssum genus and one of Bornmuellera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mglkg or 2.5%) and Alyssum markgrafli O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By Elli Nurminen

Sulphate decomposition was studied in the conditions of a typical copper flash smelting heat recovery boiler. The aim was to determine the kinetics of the copper sulphate decomposition reactions and to find out if they are likely to take place in the process conditions prevailing in an industrial HRB. The information is essential in CFD-modelling of the reactions taking place in the boiler and for optimising the process. Thermal decomposition of sulphates was studied by thermogravimetry. The experiments were conducted with a commercial copper sulphate, a partially sulphated copper oxide and an actual process flue dust. The main variables studied were temperature and gas composition of a N2-O2-SO2-mixture. The samples were characterized with SEM, optical microscope and XRD. Temperature affected the decomposition rate strongly but the gas composition had a minor effect on the kinetics. The decomposition was fastest in the partly sulphated oxide and slowest in commercial copper sulphate. Keywords: Sulphate decomposition, flash smelting, heat recovery boiler, flue dust

Jan 1, 2004

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 Gerhard Meyer

A new instrument for the determination of iron., zinc, calcium, and other metals independently directly in the fumes emitted from steelmaking processes is described. Based on the well- accepted method of X-ray fluorescence, the instrument can detect numerous metals simultaneously in the fume as well as report their concentration on a mass per unit time basis real time to a control room computer. The instrument mounts on the wall of the fume duct and can., via a small opening, directly view the hot exhaust plum inside the duct. The concentration of metal in the fume over time has been shown to change dramatically depending on process variables. Variables such as oxygen flow rate, lance height and nozzle configuration., slag condition., and episodic scrap addition can affect the presence of metal particles and fume in the exhaust. An analysis response time of 6 seconds enables better control of the steelmaking process thereby conserving primary resources and reducing environmental impact.

Jan 1, 2001

By Yue Gong, ChuanJie Cai, Jing Chen, Shaobo Zheng, Huigai Li

"MnS-AlN duplex precipitates were successfully extracted from electrical steel slabs by means of non-aqueous solution electrolysis. The three-dimensional duplex morphology became visible using emission scanning electron microscope (SEM) JSM-6700F and energy dispersive spectroscopy (EDS). The precipitation sequence of MnS and AlN in the hot process can be predicted via the three-dimensional duplex morphology. Thermodynamic calculations were carried out on account of the chemical compositions of the steel studied in this paper. The results verified that AlN nucleated on MnS, which precipitated earlier during cooling process of electrical steel. Based on the results, the material compositions and rolling temperature can be adjusted to modify their precipitation timing and morphology. This is conducive to the growth of MnS-AlN duplex precipitates and reducing the obstacles to grain growth. Finally the magnetic property of electrical steel would be improved.IntroductionElectrical steel is a kind of ferrosilicon soft magnetic alloys with extremely low carbon content. It is mainly used in the manufacture of motors, generators, transformers and varieties of teleco=unications equipment. Non-oriented electrical steel requires isotropic high magnetic induction and low iron loss [l, 2]. Precipitates in steel have a great influence on its performance [3]. On the one hand, the indirect effect of precipitates on magnetic properties is to restrict grain growth in high temperature annealing process. On the other hand, the direct effect is pinning of domain wall motion, which leads to increased hysteresis loss."

Jan 1, 2013

By Chikabumi Yamauchi, Mitsuru Tanahashi, Tsuyoshi Taniguchi, Nobuo Furuta, Toshiharu Fujisawa

"It is essential to clarify the equilibrium relations among nonmetallic inclusions of the Mn0-SiO2-CrOx system and molten stainless steel in order to control non-metallic inclusions formed by the deoxidation of stainless steel with silicon. In the present study, the phase equilibria of the MnO-SiO2-CrOx system were measured by conducting the following experiments under controlled oxygen partial pressure, Po2, at 1873 K:1) Phase equilibria of the MnO-Cr20 3 binary system were measured for Po2 = 2 x 10-6 ~2 x 102 Pa.2) Phase equilibria of the MnO-SiO2-CrOx ternary system were measured for Po2 = 2 X 10-6 Pa.Based on the results, the phase diagram of this ternary system was established under the condition of the Si-deoxidation process of stainless steel (Po2 = 2 x 10-6 Pa and T = 1873 K).IntroductionAt the deoxidation stage in steelmaking process, generally multiple deoxidizers participate in deoxidation reactions, and the composition of deoxidation products ""non-metallic inclusions"" greatly varies depending on deoxidizing efoments and their contents. In order to control non-metallic inclusions formed by the refining process of steel, it is essential to clarify the equilibrium relations among non-metallic inclusions and molten steel.Especially, during the refining process of stainless steel, nonmetallic inclusions in molten steel seem to- change as follows. After the oxidation refining, Mn-chromite is formed in molten steel as non-metallic inclusion. By the deoxidation with silicon addition (mainly less than 1 mass%), Mn-chromite inclusions are changed their compositions to Mn-silicate. Segawa et al.[l] have reported the effect of amount of silicon addition on composition and mass ratio· of non-metallic inclusions during the Sideoxidation process of 18Cr-8Ni stainless steel at 1873 K, as shown in Figuri; L At higher silicon content than 0.5 mass%, only Mn-silicate was identified as non-metallic inclusion. On the other hand, at lower silicon content, both of Mn-chromite (MnO Cr2O 3) and Mn-silicate were identified. However, the thermodynamic and the kinetic analyses of the above-mentioned Sicdeoxidation process have not been made due to lack in the thermodynamic data for the non-metallic inclusions· of the MnO-SiO2-CrOx system, such as the phase diagrams, the activities of the components, and the free energy of intermediate compounds. In relation to the phase diagram of this system, those of the MnO-SiO2 [2] and the SiO2-Cr2O 3 [3] binary systems have been only reported"

Jan 1, 2000

By Milton Syamujulu

In 2004, KCM Nkana Smelter commissioned a 1200 tonne per day flash dryer and associated dry concentrate transport and injection system on the existing Teniente Modified converter (CT) unit. The aim was to upgrade the existing smelting unit, increase copper output and improve energy efficiency. This paper reviews the design, installation and commissioning phases of the introduction of this new technology and also discusses the initial two years of operating results for both the flash dryer and injection system at Nkana.

Jan 1, 2006

By Adegbenjo Adewale Oladapo, Ibitoye Simeon Ademola, Ladiipo Olufemi Akinbiyi, Adegbola Adekunle Amos, Adeboje Taiwo Bode, Raji Fatai Olasunkanmi

The combined effects of the addition of Silicon (Si) as alloying element and low temperature annealing on the tensile properties of 70/30 brass with Nickel (Ni) and Iron (Fe) contaminants is investigated in this paper. Melts of cartridge brass were made to which 0, 0.5, 1, 2, 3 and 4 wt % of Si was added. These were sand cast into rods of 600 mm by 10 mm diameter and were thereafter machined into standard tensile test samples. Some of these samples were annealed in a muffle furnace at temperatures of 250, 300, 350, 400 and 450 oC respectively and the others were used as control. Subsequently, all the heat treated and non heat treated samples were subjected to tensile tests on a Hounsfield Extensometer and the load – extension plots retrieved were analyzed. Microstructural characterizations of the samples were carried out using Accu-Scope Optical Microscope. The results showed that cartridge brasses subjected to alloying and annealing treatments had improved tensile and yield strengths. However, the tensile properties were increased and maintained within acceptable limits at stress relieve annealing temperatures.

Jan 1, 2015

By Jafar Safarian

A new kinetic modelling technique has been applied to study the rate of MnO reduction from slags by dissolved carbon in liquid iron. Based on a consideration of the fundamental reaction kinetics, a general differential equation for the slag reduction process has been formulated, which then is solved analytically for certain special cases. By re-writing the solutions in a dimensionless form the poorly known kinetic constants are eliminated, which makes the model both flexible and applicable to a wide range of experimental conditions. For example, changes in process parameters such as temperature, metal composition, slag composition, gas composition can readily be captured along with variations in the crucible geometry. Based on a comparison with a series of experimental reduction curves being reported in the literature, it is concluded that the predictive power of the model is surprisingly good, yielding outputs that are both reliable and physically reasonable. An attractive feature of the model is that it provides an alternative way of calculating the activation energies from experimental reductions curves. For example, it suggests that the activation energy for the reduction of MnO by dissolved carbon in liquid iron is about 90 kJ/mol, which is different from the previously reported activation energies. The model also suggests that the crucible geometry, which affects both slag the volume and the resulting slag/metal interfacial area, has a significant influence on the overall reduction kinetics. This design parameter is a key to further optimisation of the process on an industrial scale.

Jan 1, 2006

By Bradford C. Wesstrom, Omar Araujo

"Impurities from an electrolytic refinery are typically extracted from the electrolyte utilizing conventional electrowinning cells. These cells are arranged in series with cascading solution flow and are commonly referred to as liberator cells. The Freeport McMoRan Copper & Gold El Paso Refinery has optimized the removal of arsenic in cascading liberator cells by utilizing two separate feed solutions. The primary feed solution is recycled liberator electrolyte and the secondary feed solution is ""neat"" tank house electrolyte. The secondary feed solution is added based on the voltage response across the individual cells utilizing independent variable frequency drive (VFD) pumps. When the voltage across a cell changes, a signal is sent to the VFD pump to maintain a cell voltage of 1.98 volts. By maintaining this voltage the copper content in each cell exits at 2-4 grams per liter. This safely optimizes the arsenic removal as copper arsenides on the liberator cathodes.IntroductionDuring the electrolytic refining of copper, impurities from the copper anode report both to the bottom of the electrolytic refining cell as slimes and to the electrolyte. The impurities which enter the electrolyte are arsenic, antimony, bismuth and nickel. The impurities that report to the electrolyte during the electrolysis process gradually increase. As these impurities increase, they are incorporated into the refined copper cathode. There are many processes that have been used to remove these impurities from refinery electrolytes. Some of them are listed as follows: solvent extraction, ion exchange, hydrogen sulfide reduction, bioreactor, adsorption onto a low - solubility metal-oxide hydrate, adsorption onto activated carbon and EMEW cells. The conventional process used by the copper refining industry for controlling the level of impurities in electrolyte involves multistage electrolytic cascading liberator cells. In these cascading liberator cells copper, arsenic, antimony and bismuth are removed as various mixed deposits from the electrolyte. Removal of these impurities is achieved through an increase in voltage resulting from the depletion of copper in the electrolyte through electrowinning. With this higher voltage, the Group Vb elements, arsenic, antimony and bismuth are deposited on the copper cathode and report as slimes to the bottom of the cells. Nickel is removed in a subsequent process."

Jan 1, 2012

By Yahui Feng, Zhiwen Wu, Chen Chen, Xin Hong

Large amounts of copper slag containing about 40 wt% iron is generated during the process of producing copper. Recovery of iron from the copper slag is very essential not only for recycling the valuable metals and mineral resources but also for protecting the environment. The purpose of this study was to investigate the possibility of separating fayalite by oxidation-reduction process into Magnetite and silicate phases in intermediate temperature condition. Experimental results show that when the oxidation reaction at 1000℃ for 120min and the oxygen flow is 0.1L/min, most fayalite decompose to hematite, less part of magnetite and silica. And then, the mixture of carbon and oxidation product is pressed into blocks and reduced to magnetite and silica at 900℃ for 90min. A magnetic product containing about 57.9wt% iron was obtained from the magnetic separation under a magnetic field strength of 100 mT.

Jan 1, 2015

By I. E. A. Aghachi

During static strain-aging of low carbon steel, when the material is pre-strained, the dislocation density increases. If totally or partially unloaded and aged for a prescribed time, interstitial solute atoms diffuse under the influence of the dislocation stress fields, thus tending to lock dislocations causing an increase in yield stress. If held for long periods at certain aging temperature, a decrease in yield stress (over-aging) is observed following the initial increase. This behaviour has been variously attributed to either recovery of cold worked dislocation structure and/or formation and coarsening of carbide precipitates. The present work demonstrates that, using a "process control" model for the competing processes of hardening and softening, dislocation recovery is responsible for over-aging of mild steel specimens under conditions tested during this investigation. Keywords: Strain-aging, Precipitation, Recovery

Jan 1, 2003

By Klaus-Markus Peters, James G. Hemrick, John Damiano

"Work was performed by Oak Ridge National Laboratory (ORNL), in collaboration with industrial refractory manufacturers, refractory users, and academic institutions, to employ novel refractory systems and techniques to reduce energy consumption of molten material processing vessels found in industries such as aluminum, glass and pulp and paper. The energy savings strategies discussed are achieved through reduction of chemical reactions, elimination of mechanical degradation caused by the service environment, reduction of temperature limitations of materials, and elimination of costly installation and repair needs. Key results of several case studies resulting from US Department of Energy (DOE) funded research programs are discussed with emphasis on applicability of these results to high temperature processing industries.IntroductionRefractory materials are limited in their application by many factors including chemical reactions between the service environment and the refractory material, mechanical degradation of the refractory material by the service environment, temperature limitations on the use of a particular refractory material, and the inability to install or repair the refractory material in a cost effective manner or while the vessel is in service. All of these limitations reduce the energy efficiency of the process as degraded refractory materials lead to loss of process heat (reduced insulation by refractories) and the need for maintenance through repair or replacement of refractory linings.This situation is conceptualized in Figure 1 which shows that when the thickness of the refractory wall is reduced by chemical or mechanical degradation, the heat losses through the wall increase exponentially. The subsequent maintenance to repair such conditions often requires cooling of the furnace or refractory lined vessel which entails loss of energy due to cooling and consumption of energy due to reheating. Additionally, production time and capability are sacrificed.Additionally, in most applications where refractories are used (metal melting furnaces, glass furnaces, steel making furnaces, gasifiers, etc.) wear of the refractory lining is not uniform. Very often, specific areas will wear (become thinner) more rapidly due to exposure to more corrosive or erosive conditions. This concept is illustrated in Figure 2, through the example of excessive metal line corrosion."

Jan 1, 2009

By Khoo Khyou Pin, Yoshiyuki Funaki, Hirotsugu Takeuchi, Ryoichi Urao, Naotatsu Asahi

"Steel is used to be ion carburized with mixing gas of methane and hydrogen. In carburizing, carbon in the methane decomposes and deposits on the steel by plasma, so methane gas flow may influence on ion carburizing of the steel. An apparatus in which works can transfer preheating, ion-carburizing and diffusion treating zones continuously was made for effective carburizing of steel. The gases were flown into above three zones with three different gas inlets. The hardness and microstructure of the works were investigated after ion carburizing and quenching. The steel is carburized deeper near the carburizing gas flow nozzle of the inlet than far from the nozzle. Hard surface layer fom1ed by quenching of ion-carburized steel.IntroductionGas carburizing is used for a surface hardening treatment which decreases fatigue and wear of the industrial parts used in automobile, machines etc. Ion and vacuum carburizing have been developed recently and applied to some industrial parts of restrictive purposes. The ion carburizing treatment which uses hollow cathode discharge (HCD ion-carburizing) is superior in energy saving, resource saving, environmental cleanness to the other carburizing treatment. Specially, carburizing energy can be saved in HCD ion-carburizing, because highly heated zone can be restricted in the range between work and subsidiary cathode where hollow cathode discharge arises, and the work is carburized in shorter tin1e in HCD ion carburizing method than other carburizing methods. Three treatments of preheating, carburizing methods and carbon potential controlling by hollow cathode discharge tried to be carried out in one continuous transferring series to carburize works more effectively, so the HCD ion-carburizing apparatus with continuous transferring system was made and gears of works were HCD ion-carburized in continuous transferring. The works were rotated themselves to get homogeneous carburizing by continuous transferring in glow of hollow cathode discharge."

Jan 1, 2000

By C. F. Ferron

A process has been developed to treat the copper gold ores from the Guelb Moghrein mine in Mauritania. The process consists of pressure leaching the sulphide concentrate, neutralising with the oxide ore, recovery of copper by SX/EW and of gold by cyanidation of the autoclave residue. This paper focuses on the pressure leaching step, and presents data from bench and pilot plant test programs. In particular, attention is drawn to the effects of temperature, grind size, neutralisation, retention time and solution recycle on the kinetics of copper dissolution from various flotation concentrates. Likely leach mechanisms are briefly discussed.

Jan 1, 2000

By Ruirui Wei, Yanhui Liu, Fangqing Yin, Meilong Hu

In China, Basic Oxygen Furnace (BOF) slag is traditionally used as an aggregate for civil engineering, for road engineering and fertilizer. In order to make full use of BOF slag, the experiments of BOF slag with high temperature roasting has been carried out and the phase transformation is studied. The BOF slag from Chongqing Iron & Steel is roasted in the electric muffle furnace at three different temperature. The influences of the high temperature roasting on change the phase composition of BOF slag was characterized by XRD. The results revealed that SFCA was produced at the high temperature in air atmosphere and melting temperature of slag was lowered. Therefore, if the BOF slag which treated by roasting was utilized in the sintering process, it is advantageous to improve the sintering strength and the formation of the liquid phase and reduce fuel consumption in the sintering production process.

Jan 1, 2015

By Oleg I. Platonov

Method of high-temperature reduction of oxygen-bearing sulfurous gas has been developed at Copper Plant (CP) of MMC ?Norilsk Nickel? Trans-Polar Division (PD) with the aim of producing elemental sulfur from Vanyukov furnace? off-gas. Non-explosive reduction technology of oxygen-bearing sulfurous gas by methane utilized at Copper Plant has been designed to separate the processes of gas heating and sulfur dioxide reduction based on different kinetic of the reactions oxygen fixing and SO2 reduction. First, natural gas promptly reacts with oxygen contained in the process gas to heat a gas mixture up to the temperature of sulfur dioxide reduction (1200C). Then isothermal reduction takes place within 1 sec. Combustion chamber (pre-chamber) design developed based on the above principles is presented. Practical experience of the two reduction reactors operation at CP since 1996 proves high efficiency of the developed reduction process. The volume efficiency rises dramatically thanks to the fact that both fuel and reducing agent are fed into the reactor volume in the form of high-speed turbulent jets providing an intensive mixing of the reacting gases. On condition of equal internal volume of the reactors, the developed process offers higher efficiency of reagent interaction resulting in sulfur conversion exceeding 90%, as compared to the equilibrium one.

Jan 1, 2006

By M. A. Halim, V. I. Lakshmanan, T. Sheikhzeinoddin, R. Roy

"Chloride metallurgy is emerging as an alternative process for the production of base metals. Process Research ORTECH Inc. (PRO) has been at the forefront of technological development of chloride metallurgy. PRO has developed an innovative technology for the production of high purity titanium dioxide, iron oxide and vanadium pentoxide from ilmenite ores and concentrates. PRO is also developing its proprietary mixed chloride technology for the extraction of vanadium from other sources such as oil shales. In this paper, results from the test work conducted at PRO for the extraction of Ti and V using a mixed chloride lixiviant are presented.IntroductionTitanium and vanadium alloys and compounds have numerous industrial applications. Titanium dioxide is used in paints, plastics, rubber, paper, inks, textiles and a number of other miscellaneous applications. Currently nanosize T1O2 is being investigated for application in the cosmetics industry. Inorganic sunscreens mainly use T1O2 or ZnO particles, which reflect and scatter ultra-violet light. T1O2 nanomaterial is also finding application in smart construction materials and coatings, as a photo-catalytic converter. Nano TiO2 can catalyze the dissociation of NOX gases and other automotive emissions, thereby reducing the smog in urban centers. After the construction material is exposed to sunlight or ultra-violet light, the T1O2 is photo-activated and degrades the pollutants.Titanium metal and titanium dioxide are produced from ilmenite (FeTiOs) or rutile (naturally occurring T1O2) ore. Only about 6% of the titanium resources are used to produce titanium metal and the rest is used to produce T1O2. Many of the titanium ore deposits currently have unacceptable levels of transition metals which limits their processing by conventional routes."

Jan 1, 2012

By Kamal Adham

Hydrochloric acid is used as lixiviant in such hydrometallurgy processes as synthetic rutile production and nickel extraction. The intermediary metal chloride is normally roasted to release gaseous HCl and a solid metal oxide. A large amount of fuel is required for this thermal regeneration, mainly to vaporize the water content of the feed solution. To conserve fuel, some energy recovery from the off-gas is currently achieved, but the fuel costs can further be reduced by process optimization and energy recovery from the gaseous, aqueous and solid products of the regenerator. Here, first the existing limitations to fuel efficiency in the industrial scale HCl regeneration roasters are described. Then, for the case of a dilute feed solution, options for pre-evaporation and fuel minimization are modeled and compared. Finally, energy recovery technologies including heat pumps, acid heat exchangers and solid waste heat boilers are described, and their potentials as the heat source for pre-evaporation of the feed are evaluated.

Jan 1, 2003