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By Linfeng Zhou, Rong Sun, Guanghui Li, Zhiwei Peng, Tao Jiang

Dust, or airborne particulate matter, from metal smelting can be either mechanically or thermally generated and it negatively affects the indoor air quality as well as the fugitive emissions from the plant. The thermally generated dust is often referred to as fume and it is typically generated whenever liquid metal comes into contact with air. For practical reasons, such as vehicle access, etc. it is often difficult to collect 100% of the fume. It is therefore highly desirable to develop processes and optimize operational procedures so that fuming can be kept to a minimum. In this series of experiments, the mechanism of active oxidation and fume formation from liquid silicomanganese under an impinging air jet in the temperature range 1400-1600°C has been explored. Characteristic properties of the fume have been established; particle diameter, shape, size distribution, and elemental composition are reported. The oxidation process is described in terms of vaporization, oxidation and agglomeration. In the boundary layer, two competing mechanisms seem to be operative in parallel: a direct oxidation of Mn vapor, and a two-step oxidation of silicon. The thermodynamic and kinetic conditions governing the two mechanisms are discussed.

Jan 1, 2016

By Robert D. Boiler, Bill Wilkie

"There is a wide choice of different types of woven filter media for hundreds of different filtration applications. Factors such as type of fiber, synthetic polymers used, weave style, fabric finishes and fabrication techniques all play an important part in selecting the best choice for a specific type of filter and process application. The purpose of this paper is to offer some basic knowledge of these factors and how they can impact the performance of a filter, the life of the media and the overall cost of operation through case studies of actual plant filtration applications.IntroductionThe use of woven filter cloth in liquid/solid separation applications is generally well known. Woven filter cloth, by the nature of the weaving process, offers unique consistency and repeatability when compared to some other filter media such as needled felts, papers, sintered structures and knitted cloth. This unique consistency and repeatability is particularly applicable to woven filter cloth produced using monofilament fibers. These fibers are consistent in shape and form the basis for a woven cloth with predictable pore size and throughput characteristics. Woven filter cloth can be used in most wet filtration applications. Typical examples are the separation of chemical and pharmaceutical solids from process liquors, waste stream solids capture, liquid foods clarification, mining separations, and polymer filtration.EnvironmentOne of the first considerations is the environmental demand of the given process. Though it is tempting to look immediately at the particles in a filtration process, it is often better to consider some of the more basic needs of the system. There are numerous materials available, both synthetic and wire cloth. Each has its own unique set of properties."

Jan 1, 2012

By Petre Stelian Nita

In small steelmaking shops, in foundries and forging plants, there are not too many option to recycle the basic slags, which are not suitable for many purposes of recycling, because of their low chemical and structural stability. A solution of an adequate recycling is a direct recycling in EAF. Several quality requirements, physico-chemical properties and proportions of slags must be analysed. The progress in this fields permites to establish an adequate proportion of recycled slag, based on enough exact computation of the related property. For oxydizing slag, obtained during melting and in the first part of decarburization operation, the problem of phosphoms contents can be analysed using the phosphate capacity (C PO34-). For reducing periods, during deoxidization operation, desulphurization also occurs and the problem of the sulphur contents can be analysed using the sulphur and sulphide capacities ( Cs / Cs) Between this two complex thermodynamic indicators of the slags. a direct relation is established, using thermodynamic aspects, resulting from the equilibrium constants for dephosphorization and desulphurization process and also, using the optical basicity of slags, computable from the chemical analysis of the slags. On this basis starting from the steel quality requirements. adequate strategies can be established in order to obtain high rates of recycling (between 50-80%) of steelmaking slags. Important cost savings are obtained through this procedure, based on the correct amounts of the fresh lime, iron ore and fluidizers. Keywords: Slag, Properties, Recycling

Jan 1, 2003

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Guangxin Wu, Shunli Zhao

"Nucleation and growth model based on a 3D CAFE model, which was incorporated with macro heat transfer calculation within ProCAST software was used to predict the solidification microstructure of austenitic stainless steel in twin-roll strip casting. The simulation results of solidification microstructure agreed well with experimental results of austenitic stainless steel. The effect of different casting process parameters on the solidification microstructure was simulated. The predicted results show that solidification microstructure is obviously sensitive to superheat and convection heat transfer coefficient. With the increase of superheat, the grain density decrease and the proportion of columnar crystal increase. In addition, the proportion of columnar grains increases when convection heat transfer coefficient increases. Thus, it was demonstrated that the solidification microstructure evolution of twin-roll strip casting could be predicted reasonably by using this model.IntroductionNear-net-shape casting technology is an important research area in the iron and steel industry today. Twin-roll strip casting represents a major area of concentration of near-net-shape casting technology. It has been widely used for its outstanding advantages, such as extended solubility of alloying elements, refined solidification microstructure and reduced microsegregation [1]. Furthermore, it is the most environmentally friendly, energy saving, and C02-sensitive way to produce steel strips [2]. Therefore, much attention remains to be paid to this aspect. A lot of published works indicated that the solidification microstructure of twin-roll thin strip has obvious effect on the thin strip properties [3, 4]. For the accurate control of parameters of the process are made difficult due to the complicated process and the multi-fold factors, great attentions have been paid to numerical simulations to provide insight into the solidification behaviors of the thin strip formed by twin-roll strip casting [5, 6].Simulations of casting solidification can provide a method to predict microstructure and to improving strip quality by controlling the process parameters."

Jan 1, 2014

By S. Castro, P. Alfaro, C. Moctezuma

IMMSA operates a conventional roasting-leaching-purification-electrolysis plant for the production of zinc from concentrates in San Luis Potosi, Mexico. The leaching circuit was designed to take into consideration a feed mixture to the roaster with a maximum iron content of 7%. Since the start-up of the plant in 1982, the zinc recovery increased to 94.5%. However, an increase in the iron content in 1997 caused an important decrease in the global zinc recovery. Two new steps were added to the leaching circuit and modifications were made to the other steps in order to increase zinc extraction. Two new automated press filters were installed to replace the original vacuum drum filters and to minimize soluble zinc losses. Additionally, the residue treatment steps in purification were modified and a calcium removal circuit is just starting operation. These actions, besides improving the operations, have as the main objective to increase the global zinc recovery to levels above 94.5%.

Jan 1, 2000

By C. E. Dodson

Conventionally hydrometallurgical recovery processes from sulphide concentrates include roasting, leaching, precipitation, impurity removal and zinc electrowinning. The use of the novel (yet commercially proven in other mineral and metallurgical industries) TORBED process reactor for the flash roasting of sulphides will be proposed. The potential advantages in its application will be discussed including very fine particle processing capability, lower cost smaller roasters, waste minimization, improved leaching efficiency and overall process simplification.

Jan 1, 1999

By K. Noda

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. is carrying out a low cost production using a Tamano Type Flash Smelting Furnace (T-FSF), which is an improved version of Outokumpu Type Flash Smelting Furnace but without slag cleaning furnace and also by developing its own coke combustion technology. Coke combustion technology that is the basis of the system has been improved several times and, at present, it has evolved to a stage where it can be reproduced on the Computer guided system for Coke Combustion in the T-FSF (CCCT) using a general- purpose computer. This CCCT is featured by 'its trend control and predicting function, and an operator can freely control the operation parameters so as to control the operation flexibly. We have recently developed an overall energy reduction system covering the Smelting Plant to Sulfuric Acid Plant, which we call an Optimum Low Cost Operation System (OLCO) to reconsider the energy costs including coke, heavy fuel oil, and electric power. In this report, we would like to present the recent operation of T-FSF based on CCCT as well as the optimum energy operation utilizing OLCO system.

Jan 1, 2002

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

Linz-Donawitz converter gas (LDG) or basic oxygen steelmaking gas (BOSG) is one of the most important secondary energy sources in iron and steel industry, whose effective use plays a vital role in energy saving and emission reduction. However, the generation of LDG suffers from great fluctuation with respect to the production status of steel making. Therefore, a long term prediction model of LDG generation would be essential in gas system balancing and optimization. In this paper, a long term prediction model for the generation volume of LDG was proposed based on the steelmaking production estimation from Gantt chart and k-means clustering algorithm. Compared with the previous model, this model considered the influence of different steel type on LDG generation. The experimental results of a steel plant demonstrate that the proposed model exhibits high accuracy and can provide an effective guidance for balancing and scheduling of byproduct gases.

Jan 1, 2016

By B. Sereda

As it is known the creation and development of new titanic alloys has been problematic up to now. They can be used in aircraft and vehicle construction, shipbuilding and as materials for keeping static loadings in high-temperature environments. In this work the synthesis of various titan aluminides is investigated. Mathematical model of structurization process was done. On the base of retrieved model the mechanisms of structurization in systems Ti + Al and Ti + 3Al was determined. Experimental researches were done at two different modes: burning and thermal spontaneous ignition. The method of retrieving compacted products combusted in SHS conditions (SHS-compacting) was used to gain these intermetallic compounds. The physical and thermal characteristics of technological process and their influence on structurization, homogeneity of structure and porosity of titan aluminides have been simulated and researched. It is established that the SHS-compactizing technology is fully capable of supervising the process of structurizations with the whole complex of advantages and can be applied for receiving qualitative titan aluminides with the set of chemical-physical properties.

Jan 1, 2010

By E. N. Mounsey

Ausmelt Technology was selected by Bindura Nickel Corporation (BNC) as the basis for a new copper circuit to process nickel plant copper leach residue to blister, anode and finally cathode copper and recover PGM values at the Bindura Smelter Refinery (BSR). The process selected, based on Ausmelt Technology to smelt and convert the residue to matte and blister copper and produce a discard slag, is novel incorporating smelting, converting and slag reduction process steps in a single Ausmelt vessel. The process demands a high quality blister copper product with low levels of arsenic and nickel. This paper reviews the project and the initial operational results to the end of 1997 of the Ausmelt Top Submerged Lancing (TSL) smelter and discusses the implications for the wider TSL converter market.

Jan 1, 1998

By Aurelian Buzaianu, Cristian-Aurelian Popescu, Gabriela Popescu, Petru Moldovan

"A lot of scraps result in processing of composite materials which contain metallic phases that can be recovered and used again in different field. Considering this point of view the aim of the paper was to separate and recover aluminum from aluminum matrix/graphite composites. The separation and recovery of aluminum alloy from aluminum alloy/graphite composites was done by treatment with halide molten salts. As halide salts were used flux tablets that collect the ceramic particles in dross. After dross separation, was used filtration in order to separate the aluminum matrix from the other impurities.Samples from the recovered alloy were analyzed using chemical analysis, optical and electron microscopy, as well as X-ray diffraction. The desired composition of the aluminum alloy obtained from scraps could be reached by some addition of metals to the metallic phase. From optical microscopy it was obvious that the structure of the aluminum alloy obtained after composite reclamation consists large particle of silicon, eutectic, a-Al solid solution and other phases like Fe, Si, Mg and Ni, or some compounds like CuAl2. 1. IntroductionThe research on the recycling and reclamation of metal-matrix composites (MMCs) becomes active to preserve the natural environment, as environmental requirements become stricter, to save energy, and to reduce garbage. In case of recycled aluminum alloy ingot the production energy is about 3 pct of that of the new ingot. This evidence strongly supports the necessity to recycling of aluminum alloys. Among aluminum alloys, metal matrix composites have high strength and elastic modulus, and also good were resistance. These materials have been developed to meet the demand properties which exceeds that of the ordinary materials, and to save energy."

Jan 1, 2008

By Janene Barter

Telfer Gold Mine treats both gold/copper oxide and sulfide ores in a remote location in the Great Sandy Desert, Western Australia. Currently, the oxide gold ore is treated in a conventional CIL circuit by blending the low and high grade copper ores to minimise cyanide consumption and allow smooth operation. The sulfide ore is treated through a flotation circuit to produce pyrite and copper concentrates. The pyrite concentrate is treated in the CIL. Copper concentrate is stockpiled and sold to a smelter for further processing. In recent times, as the depth of the pit has increased the copper head grade has also increased, to the point where the ore was becoming uneconomical to treat. In addition, it was desirable to reduce the amount of cyanide reporting to the tails dam both from an environmental and economical viewpoint. Newcrest Mining Limited engaged GRD Minproc Limited to evaluated a process to reduce the amount of cyanide entering the tail dam with consideration given to copper recovery. From this investigation, the Sulfidisation, Acidification, Recycle and Thickening (SART) process was selected. A detailed testwork program for SART was undertaken with the objective to design and construct a SART plant at Telfer. This paper outlines how the SART process was chosen and summarises the testwork that led to the design of the SART plant. It also touches on some of the important issues for designing this type of process.

Jan 1, 1998

By Carlos A. Ferreira, Betina Hansen, Marco A. S. Rodrigues, Marcela P. Proença

"Nowadays, the concern with the reduction of industrial pollution has motivated researchers to found out new technologies for treatment of industrial waste. The clean technologies, as electrodialysis, are capable of treating these residues, minimizing the impacts when they are discarded directly on the environment. Membranes of SPS/HIPS, PAniCSA/SPS/HIPS, SPAN/SPS/HIPS were developed using chemical mixture method. Membranes were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) and Scanning Electronic Microscopy (SEM). Membranes were submitted to electrical polarization and to electrodialysis at NaCl and KCl solutions, in order to determine ionic transport through the membranes. Results were compared with commercial membranes. The average percent extraction for Na+ ions obtained by membrane was beyond 20%.IntroductionThe high environmental impact caused by the galvanoplastic industries represents today a world concern(1). In the galvanoplasty, thin metallic layers are deposited on metallic surfaces(2) through chemical methods or electrochemical process. This industrial process presents some disadvantages that limit its utilization, as the generation of toxic effluents containing concentrations of heavy metals usually above the limits allowed for his release in receiving bodies(1), the production of galvanic sludge which is considered hazardous waste and that is very difficult to treat, beyond the high consumption of water (3).Stimulated by the development of new ion-exchanged membranes with high selectivity, lower electrical resistance, and improved thermal, chemical and mechanical properties, the use of electrodialysis in the wastewater treatment has recently gained a broader interest(5). The electrodialysis (ED) is a mass separation process in which electrically charged membranes and an electrical potential difference are used to separate ionic species from an aqueous solution(5). The technique permits the recovery and the reutilization of the waste products from the industrial process, avoiding the discharge of them on the environmental (acting as clean technology)."

Jan 1, 2008

By Maura Malone, Neil Gao, Daniel Liu

"Corrosion is the primary failure mode for aluminum cathode sheets used in Teck's Trail Operations electrolytic zinc plant. It was observed that the corrosion performance of Al cathodes from different suppliers varied considerably. This suggests that the material properties of Al cathodes have a strong influence on corrosion resistance. In the current study, various types of Al alloys, including 1050, 1060, 1070, HIS and 1090, were characterized through chemical analysis, corrosion testing, mechanical testing and metallography. The results are discussed with a focus on the effects of impurity elements and second phase particles on corrosion resistance. The findings were used to improve the Al cathode sheet specification and to develop a standardized screening procedure which details qualification steps for comprehensive evaluation prior to a plant trial.IntroductionAluminum (Al) cathode replacement is a major operating expense at Teck's Trail Operations zinc electrolytic plant. Currently, approximately 0.5% of daily stripped Al cathodes are removed from service because of failures caused mainly by corrosion. Edge corrosion and acid (solution) line corrosion are the most severe types of corrosion, resulting in more than 50% of cathode failures.Corrosion of Al cathodes has been intensively investigated for over two decades and the origins and mechanisms of Al cathode corrosion are well understood [1-4]. Halide anions contained in the electrolyte are the primary culprits for the corrosion and sticking problems of Al cathodes. Both fluoride (F') and chloride (Cl"") result in localized passivity breakdown on the surface of the Al cathode, causing pitting corrosion. Bouarzaiga investigated the corrosion of Al cathode samples partially immersed in electrolyte and found that the formation of Ch at the electrolyte/air interface was the primary contributor to solution line corrosion [2]. Because of the significant impact of F"" and Cl"" on Al cathode corrosion, it is imperative to maintain these concentrations as low as possible in the electrolyte."

Jan 1, 2012

By Baokuan Li, Fang Wang, Meilong Shan

"As the advantage of uniform bus loading, the electroslag remelting (ESR) furnaces with three - phase installation by delta or star connection are mainly used to produce the large or super large ingot. The electrical efficiency is significantly improved as the short circuiting through the molten slag. However, little is found about fiindamental research on the electromagnetic field of the ESR system with three -phase installation. A three-dimensional (3D) finite element model was developed to simulate the current density, magnetic field, electromagnetic force and Joule heating for a system of electrode, slag and ingot in the ESR system with three -phase installation.IntroductionThe metallurgical performance of the ingot is the fundament and precondition to obtain the large forging of high quality, which has a critical role in the producing of forging. The electroslag process (ESR) to product the metal materials of high homogenization and clarity become more and more popular[1].The electroslag process is a special smelting technology of producing small ingots, which originate in 1950[2].At present the three, four or six electrode is used in large scale electroslag furnace. It has been found that the deeper molten pool and the wider of the two-phase zone with only one large diameter of electrode to product large ingot effect the solidification microstructure of ingot[3]. However, the molten pool becomes shallow relatively with several electrodes producing the large ingot, which is benefit to the solidification microstructure of ingot. Three electrodes electroslag remelting furnace take the three phase equilibrium power supply to making the load and electric power network balance, avoiding the distortion phenomenon induced by single phase power supply and saving electric power. It also can uniformize the distribution of heat source."

Jan 1, 2012

By Wenying Liu

The effect of aeration on chalcocite heap leaching was studied by analyzing the historical data from two chalcocite heap leach pads located in Chile, one with aeration and the other without aeration. The data showed that the copper leaching kinetics of the aerated heap was greater than that of the unaerated heap within a certain leaching period, after which there was no effect of aeration on the copper leaching kinetics. The total acid consumption per ton of ore processed was higher in the case of aeration, which was supported by the higher pH of the PLS. But the net acid consumption per ton of copper produced was the same in the two cases. Approximately 5% of the total iron added to the unaerated heap was precipitated inside the heap. In contrast, there was no net iron precipitation or generation inside the aerated heap. Bacteria activities were thought to occur even in the unaerated heap, but the extent was much less than in the aerated heap. Given the importance of forced aeration in chalcocite heap bioleaching, mathematical modelling will be applied in the future work to assist the optimization of the aeration system design.

By Patricio Barrios

This paper discusses the revamp and expansion of Atlantic Copper's (formerly Rio Tinto Metal) copper smelter located at Huelva, Spain. The plant was expanded from 150,000 to 270,000 tpy new copper in anodes, and from 133,000 to 215,000 tpy cathodes. Lurgi successfully executed this contract on a lump-sum, turnkey basis in just 19 months. The Lurgi on-site task force performed this work in close cooperation with Atlantic Copper's personnel, with a minimum of disruption in the plant's ongoing operation. The contractual performance parameters were achieved to the client's satisfaction shortly after the mechanical completion of the respective plant sections.

Jan 1, 1998

By C. Lupi

In 1996 the Italian Agency for Environmental Protection (ANPA) has initiated a study of the environmental impact of the industrial sector of steel produced by Electric Arc Furnace (EAF). Within the framework of this study a hydrometallurgical process to treat EAF dusts was considered and developed. The paper describes the zinc and lead recovery from fumes coming from carbon steel production. The zinc extraction consists in acidic leaching followed by SX-EW steps. The leaching sludge containing lead sulfates was treated to obtain pure lead salt and inert solid residue. The whole process, that minimizes effluents by recycling the main liquid streams, has been developed to obtain marketable products. The solid waste, containing spinels, was subjected to elution tests in order to verify its compatibility with environmental regulation. The process, that has been set-up and tested in the laboratories of the University of Rome, will be transferred and studied on a pilot plant in order to assess its industrial and economical feasibility.

Jan 1, 1999

Laboratory trials were performed in an induction furnace to study droplet formation during lance blowing. Compressed air was blown on a molten iron bath consisting of iron alloyed with carbon and silicon. Steel droplets were collected using a specially designed sampler. The average steel droplet composition and the oxide layer thickness were determined using scanning electron microscopy combined with energy dispersed spectroscopy. In addition, the concentration gradient of elements was determined using a microprobe. It should be noted that a special technique had to be developed in order to prepare the droplet sample. The size distribution and composition of the droplets was also determined using the microprobe. It was found that the carbon content in the droplets was lower than the carbon content in the bulk.

Jan 1, 2006

By Jean-Christophe Gebelin, Mark Jolly, Samantha Jones

"The de-waxing process in investment casting is truly a black art which is carried out in a black hole - the autoclave. The process involves exposing wax, coated by a porous ceramic shell, to steam at a pressure of 10 bar and a temperature of about 180°C. The processes which then occur are truly multi-media and multi-physics. Steam condenses in the porous ceramic, wax melts and flows, the shells expand and sometimes crack. Why the shells crack is one of the most difficult questions asked in the industry.Modelling and validating the de-waxing process is not simple. The IRC at the University of Birmingham is attempting to model this process using Physica+ a code developed in the UK. This paper will present the latest results in this attempt to model one of the casting industries most intractable problems.IntroductionThe de-waxing process using an autoclave involves the following physical phenomena:· Flow of the steam in the autoclave;· Heat transfer from the steam to the wax, possibly through the shell;· Melting and flow of the wax.At the same time, other phenomena may occur, such as the flow of the steam through the shell, the condensation of the steam on the shell surface and on the wax pattern surface, the flow of wax the through the shell, etc ...This shows how complex the de-waxing process is from a physical point of view. The main defect that appears during this process is the cracking of the shell. Previous modelling work carried out by Snow [1] has shown that it is possible to predict the stress in the shell, making numerous assumptions. In this paper, the modelling to predict the state of stress in the shell that is currently in development at the University of Birmingham is presented together with the presentation ofthe physical phenomena to model and the assumptions used. The parameters that are needed in such models will also be discussed, and some experimental work undertaken at the moment presented."

Jan 1, 2001