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By René Bustamante

A GPSS/H simulation is beeing done for a traditional smelter of copper, which envolves a reberberatory furnace, a set of Peirce Smith converters (PSC) and a refining furnace. The objective is to try different plant layouts, being the handling of liquid material at high temperature one the mainly concern, this envolves a study of the ladles and cranes used. Some of the modifications that can be evaluated through the model is the role of oxygen potential when tonnage oxygen is used, number of cranes, PSCs in operation, etc.

Jan 1, 1992

By M. E. Karabin, R. J. O'Malley

"A mathematical model of the roll casting process has been developed which predicts macro-variables, such as roll separating force, roll torque, and strip exit speed for a range of roll speeds. Continuum variables, such as interface pressure, interface shear stress, freeze-front shape, and internal temperature distribution are also predicted.The model consists of two independent segments: solidification and rolling. The solidification model is two-dimensional (thickness and rolling direction) and is capable of handling alloy solidification. The solidification model is employed until solidification through the thickness is complete, then the rolling solution is activated.The rolling model is a one-dimensional (rolling direction) mechanical solution based on the von Karman approach, coupled with a two-dimensional thermal solution. The flow stress is expressed as a function of the average through-thickness temperature of the strip.Experiments were performed using a laboratory roll caster to test and refine the model. Experimental strip exit temperatures were used as input to the model. Experimental and predicted roll torque and strip exit speea were forced into agreement at a single reference roll speed to obtain values for the coefficient of friction and the interfacial heat transfer coefficient. Using these values, good agreement was obtained between predicted and experimental torque and strip exit speed over the entire range of roll speeds examined."

Jan 1, 1986

By Alexander I. Raitchenko

"An electroconductive viscous liquid may flow in laminar or turbulent regime under Lorentz-force generated by the intercrossed electric current and magnetic field. When there is a starting flat layer between hard and free boundaries with surface tension the spatial Lorentz-force can create a specific stationary regime of flow: the plane free surface will transform into the wavy one, and the movement in the depth will be not laminar and not turbulent, but this regime will be characterized by organized forms with indications of ""rolling of long cylindrical drops"". Wave-length is determined by the viscosity, the density, the surface tension, the average thickness of layer, and Lorentz-force. ·The limit of wavy regime is determined by most long of wave which is directly proportional to the critical value of specific flow and inversely proportional to the kinetic viscosity. The proper critical value of Reynolds number is determined by the dimensionless combination containing surface tension, density, viscosity, and Lorentz-force. The mentioned dimensio.nless combination in our case is some criterion substituting the known Kapitsa number for case of the thin viscous liquid layers under gravity. Spreading of admixture by mechanism of wavy regime is more rapid than by common diffusion or by laminar flow. The suggested conception can be a contribution into the theoretical basis for elaboration of some specific liquid metals technologies."

Jan 1, 1999

By Ian Masters, A. R. Khoei, D. T. Gethin

This paper describes an experimental investigation into the effects of process parameters on product quality during an aluminum recycling process. In order to build a model relating recovery to the process parameter variables and then use the model for prediction, process optimisation, or process control, a historical data analysis is employed by observing patterns in the datalogged information at IMCO Recycling Ltd. In previous work, we emphasised the importance of expressing the results of an experiment quantitatively, by implementation of a Taguchi approach, to facilitate understanding, interpretation and implementation. This research presents the technical tools that are needed to achieve quality improvement in recycling of aluminum. In this study we apply the use of historical data matching through a Taguchi orthogonal analysis, in order to control and improve the quality characteristic. For this purpose, a numerical model is developed to characterise the inputs and outputs of the process. A response surface methodology (RSM) is employed to find a suitable approximation for the true functional relationship between response and the process parameter variables. The method of least squares is used to estimate the approximating polynomials. Subsequently, Taguchi's method is used to determine the relative significance of each of the parameters. Finally, process management software (written in Visual Basic) is described, and its interface with the process modelling and optimisation routines is discussed.

Jan 1, 2000

By Peng Fan

Nitride capacity is usually employed as the measure of slag?s ability to remove nitrogen from liquid metal, since nitrogen distribution ratio between slag and metal can be calculated from nitride capacity provided that the value of oxygen activity in liquid metal is available. However, during liquid metal refining processes, oxygen activity in liquid metal is usually unknown and thus it is impossible to get nitrogen distribution ratio from nitride capacity under this usual condition. In this paper, thermodynamic analysis indicates that the activity coefficient of nitride in slag can be used to measure slag?s ability to remove nitrogen from liquid metal, because nitrogen distribution ratio between slag and metal can be calculated from the activity coefficient of nitride in slag provided that the content of oxygen potential controlling element like Al in liquid metal is available. Review of reported nitrogen removal studies and our recent study has verified that for a given Al content in metal, the lower the AlN activity coefficient in slag is, the higher the nitrogen distribution ratio. Titanium monoxide based slag has been found to be much more effective to remove nitrogen than other slags. Since Al content in liquid metal is usually available during liquid metal refining processes, AlN seems to be a better measure of slag?s ability to remove nitrogen from liquid metal.

Jan 1, 2006

By Biserka Lucheva, Tzonio Tzonev

"Recycling of aluminum scrap and dross is significant in the economic and energy saving, as well as in the environmental protection. Recovery of metal aluminum depends on many factors. The aim of this work is to investigate experimentally the metal recovery under different conditions. The processing of aluminum dross was carried out in DC electric arc rotary furnace. The optimal technological parameters are determined. It is turned out that the presence of crushing refractory bodies during the processing of the aluminum dross in the rotary furnace increases the degree of aluminum recovery with about 10 %.IntroductionCompact and granular aluminum dross are used for the fulfillment of the experiments, which were obtained by salt free melting of aluminum scrap. The only preliminary preparation of the compact dross is crushing them into proper size, in compliance with the size of the opening for furnace charging and removing of fraction – 1 mm. The granular dross is subjected to sieving also with the purpose to remove the fraction – 1 mm. In these conditions the content of the metal phase in the compact dross is 72 %, and in the granular – 77 %. The processing of aluminum dross was carried out in DC electric arc rotary furnace (Figure 1).The purpose of this research is to investigate experimentally the metal recovery under different conditions and to establish the dominant factors, which need to be controlled."

Jan 1, 2008

By Józef Czernecki

The Polish copper concentrates are characterised by low content of sulphur and iron. At KGHM Polska Miedz S.A. two copper production technologies are in use. The shaft furnace process is used at the Legnica Copper Smelter and the Glogów I Copper Smelter. A single-stage direct to blister Outokumpu flash smelting process is used at the- Glogów II Copper Smelter. Melting copper concentrates in the shaft furnaces is carried out in a reducing atmosphere and the product obtained is a matte. Instead, a result of melting copper concentrates by an oxidising flash process blister copper of a quality similar to that of converter copper is obtained. The annual copper production at KGHM Polska Miedz S.A. exceeds 450,000 tons. Another important metal is silver produced from slimes from copper electrolysis (about 1000 t/y). Moreover, such metals as Pb, Ni, Se, As, Au and other precious metals, including Pt and Pd, are recovered from various semiproducts. This paper presents technological flow sheet of the copper production in plants using the shaft furnaces and in another plant in which a single-state flash process is applied. Characteristics of products, methods of their utilisation, main parameters of particular technological operations, and advantages and shortcomings of the solution applied are presented. There are also discussed: the natural environment protection as well as directions of the KGHM Polska Miedz S.A. plants modernisation.

Jan 1, 1999

By Hye-Sung Kim, Dong-Wha Kum, Gyeungho Kim

"Mechanical alloying is an effective way to finely distribute inert dispersoids in AI-TM (TM is a transition metal element) systems. It is considered that high melting point aluminides are formed by precipitation from the supersaturated aluminum matrix. The analysis is based on the fact that much higher content of TM than the solubility limit can be dissolved in alpha aluminum during the high energy ball milling. Nonetheless, the role of undissolved TM particles affecting the formation of aluminides is not suitably considered. In this paper, authors present experimental observation on the formation of Ab3Ti particles from mechanically alloyed AI-Ti alloys in the hyper-peritectic region. This study showed that, in the mechanically alloyed AI-20wt%Ti specimen, intermediate phase of cubic Ab3Ti and tetragonal AIz4Tis formed at 300 - 400°C and 400 - 500°C, respectively, before the MA-state reaches to the global equilibrium at higher temperatures. The formation behavior of Lh- Ab3Ti is interpreted by interdiffusion of Al and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiating the formation of Ab3Ti phase during annealing.IntroductionInterest in the hyper-peritectic AI-Ti alloys is based on industrial demand for high-modulus and high-temperature aluminum alloys. Earlier works on hyper-peritectic AI-Ti alloys with 4 to 12wt%Ti show that these alloys are strong at ambient temperature and maintain high strength above 300°C when titanium-trialuminide (e.g., Ab3Ti) is finely distributed in the aluminum matrix [1,2]. High melting point and high stiffness with low density of AbTi make the AI-Ti alloys strong with greater thermal stability while keeping weight savings as much as possible. Titanium in aluminum shares other merits of transition metal additions because Ti solubility in Al is low (i.e., 1.l5wt%Ti at 665°C and virtually zero below 400°C), and fine dispersion of Ab3Ti particles is readily accomplished and resists grain coarsening effectively."

Jan 1, 1996

By David E. Hardt

"One of the critical variables to be controlled during arc welding is the size or geometry of the weld pool. The measurement of pool geometry has become an increasingly important problem with the advance of welding automation and control, and this paper addresses that problem. The basic concept of pool size estimation via measurement of pool dynamics is presented. The theory underlying this concept is discussed and is followed by a review of the current work in this area. It is concluded that pool dynamics can be characterized by natural frequencies of oscillation, for stationary welds, and that these can be measured by appropriate signal processing performed on the arc voltage. However, it appears that only full penetration welds show a strong correlation between weld size and natural frequency. Also, the extension of these results to the realistic case of moving welds has yet to be considered in detail. Nonetheless, this method of in-process measurement for real-time weld process control is still quite attractive where applicable since it can be accomplished simply by modifying the arc current schedule and by signal processing of the arc voltage.INTRODUCTUIONThe study of welding process control has been dominated by research into methods of in processing sensing of the weld pool geometry. While it has been shown feasible to measure the topside pool geometry using video methods [1,2], the penetration or backside bead width have remained elusive quantities. This is particularly true if a topside sensor location is required.The concept of using weld pool motion as a pool geometry sensing method was proposed by Hardt et al. [3] and later demonstrated by Hardt and Zacksenhouse [5] and Richardson and Renwick [6]. The concept is based on the fluid dynamics of a pool constrained by a solid container and by significant surface tension forces (i.e. a small shallow pool, not a ""pond"" or ""lake""). Such a pool, if subjected to external forces, will exhibit a surface motion is a function of that force, the properties of the fluid, the surface tension, and the shape of the container. Thus, if this motion can be excited and measured, and the relationship to the pool geometry determined, a means of sensing pool shape will exist."

Jan 1, 1986

By E. A. Werner, A. Pichler, A. Spalek, G. Reisner, P. Stiaszny

"Interstitial free (IF) sheet steels are used for complex shaped parts because of their excellent formability. If a deep drawn part is subjected· to a impact deformation at low temperature brittle fracture of the part may occur. This phenomenon\ is called secondary work embrittlement (SWE). One possibility to characterize this material/structural behavior is the drop-weight test. The result of .this .test is a temperature at and below which a crack can initiated in a deep drawn part under the investigated set of parameters. This paper addresses the influence of the preforming process on the sus- . . ceptibili.ty of IF steels to SWE.IntroductionInterstiiial:free (IF-) steels are frequently used in the automotive industry for complex· shaped p·arts because of their excellent deep drawability. The microstructure of the steel consists of a highly ductile ferritic matrix with embedded precipitates of nitrides and/or carbides. Brittle fracture can occur in deep drawn parts, if they are subjected to a high speed deformation at lo""w temperature. This phenomenon is called ~econdary Work gmbrittlement (SWE) [1-11]. Up to now there are no standardized testing procedures available to quantify the sensibility of IF-sheet steel to SWE. Neveitheless, a reasonable testing procedure which allows to quantify the tendency of a predeformed part to SWE is necessary for further material development. A commonly used test method is the drop-weight test performed at low temperatures. In such ·tests a cone-like drop weight expands a deep drawn cylindrical cup [l-3, 6, 8, 9, 11]. From this expansion experiment the temperature is determined at and below which a brittle crack can be initiated in the deep drawn cup under the investigated impact test parameters. The highest measured temperature at which a deep drawn cup fails by brittle fracture is called frack appearances !emperature (CAPT). The lower the value of the CAPT the lower is the sensibility of a deep drawn part of IF-sheet steel to SWE. This paper aims to clarify the role of the preforming process on the impact behavior of an IF steel. For this purpose a numerical analysis of the deep drawing process and cup expansion tests are conducted."

Jan 1, 2000

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 Antonio de Lucas, Juan Francisco Rodríguez, Ignacio Gracia, Mª Teresa García

"The amount of waste of Polystyrene (PS) foams is increasing in last years due to their use in insulation, protecting and, storing many different food products. Conventional methods of recycling such as crushing and shrinking by heated air or frictional heat have the disadvantages of molecular degradation, resulting in a reduction of the quality of the recycled polymer. Dissolution and shrinking with suitable solvents is one of the cheapest and more efficient ways of polystyrene recycling but in the process of the solvent recovery by distillation a certain degree of molecular degradation is produced. In this way, CO2 supercritical technology appears as an interesting alternative for the elimination of solvent. This work proposes a global process to polystyrene recycling in two steps: a polystyrene dissolution with a suitable “green” solvent followed by its elimination by supercritical tecnologhy. In order to develop a “green process” the constituents of essential oils, limonene, terpinene, cymene, and phellandrene, are selected as the most appropriated solvents. Introduction In the last years, disposal of the non-biodegradable plastic wastes has been recognized as a serious environmental problem. Recycling these wastes has great interest in order to prevent the environmental pollution and to preserve natural sources (1, 2, 3). Since the Polystyrene foams (PS) is one of the most used foam in isolation, protecting and food storage most of recycling work is concerned with this polyolefin (4). The two main alternatives for treating polymer wastes are energy recycling, where wastes are incinerated, and mechanical recycling (5). Environmental argumentations such as toxic emissions are building up a public resistance against incineration process (6). Mechanical recycling is a popular recovery path for manufacturers and is carried out on single-polymer waste streams. Any way, the market for recycled products can only be found if the quality is close to that of the original. Unfortunately the process of classification and further recovery of these wastes makes them often more expensive than virgin plastic (7, 8). Solvent extraction is one of the cheapest and more efficient ways for PS recycling. If it is done in house of waste producers the separation between plastics could be easy and effective and the transport costs would be eliminated."

Jan 1, 2008

By Xiangjun Zuo, Lifeng Zhang

"Printed Wiring Board (PWB) is a platform upon which microelectronic components such as semiconductor chips and capacitors are mounted. It is also called printed circuit board (PCB). In the PWBs, the organic substances are approximately 72%. The main composition of organic substances in PWBs is ethoxyline resin bromide or ethoxyline resin chlorinate. Depending on the different application and design of the PWB, various metals may be used in the manufacturing process, including precious metals such as copper, lead, silver, gold, platinum, and toxic metals such as mercury, cadmium, barium, gallium, cadmium, lead, bismuth. The current paper reviewed the recycling process for waste PWB materials, including mechanical recycling, combustion for energy recovery and different pyrolysis processes, such as vacuum pyrolysis, atmospheric inert pyrolysi and flux pyrolysis process, and hydrometallurgical recycling process.Backgrounds of Electronic ScrapsProduction and use of electrical and electronic equipment (EEE), such as TV sets, computers, mobile phones and many other daily-life items, have dramatically increased over past decades, while the lifespan of many products becomes shorter"". The rapid innovation in technology in past decades has resulted in availability of cheaper and better electronic products in the market. Thus the production of waste electrical and electronic equipment (WEEE) is also increasing, with estimates of 20-50 million tons per year being generated worldwide2), and it is a problem that governments and policy makers have to handle W). WEEE is also called ""E-wastes"" or ""E-scraps"". From the points of view of recycling and the valuable materials in the used EEE, ""E-scrap"" is more appropriate than ""E-waste"" since the used EEE are not real wastes to be dumped but had much benefit to recycle. In the US, it was estimated that over 315 million computers between 1997 and 2004 and 185 million computers between 2004 and 2007 would become obsolete 5). E-scrap is the fastest-growing part of the U.S. garbage stream 6). It is estimated that only 20% of the E-scrap generated within the US is currently collected and treated, with as much as 80% being unaccounted for7)."

Jan 1, 2011

By S. -H. Jeon, Y. -S. Choi

"The three dimensional current distribution on the rectangular cathode is predicted using a boundary element method with a linear element of trigonal type. The effect of cell geometry and anode shape on current distribution is simulated. Calculated results compare well with experimental results. The proper combination of anode size and distance between electrodes increase the current uniformity.The importance of electrodeposition as a fabrication technology in the electronics industry is large and growing. The main advantages of this wet processing method, in comparison to other dry processing methods, lie in its high yield, rapid processing and low cost. In nearly every application of electrodeposition the pursuit of deposit uniformity, especially thickness uniformity, has been technically imperative. The thickness uniformity of the deposit depends largely on the current distribution over the cathode. The current distribution is primarily determined by the geometrical characteristics of the electrodes and the cell. Also the polarization at the electrode surface and the mass transfer affect the current distribution.The current distribution is an important consideration for those involved in designing electrochemical systems and electroplating systems in particular. Although it is important, the common practice in industry is to use trial and error method to design the cell that optimize the uniformity of current distributions in electroplating. The purpose of this paper is to illustrate the useof boundary element method to predict three-dimensional current distribution in rectangular cell.The calculation of the current distribution is possible by various numerical techniques, which include the finite difference method (FDM)1, the finite element method (FEM)2, and the boundary element method (BEM)3,4. These methods of the numerical calculation have various problems, respectively, but the BEM is considered to be the most efficient. This is due to the fact that the BEM has the advantage of solving field equations only on the surface of a calculation domain. A good comparison between the BEM and the FEM for the secondary current distribution in a Hull cell was made by Matlosz et al.5The fundamentals on the theory of current distribution in electroplating are well-established in the literature by a number of authors.6, 7, 8 However, a small fraction of these works have been specially addressed to three-dimensional analysis, and, mostly thel·10 have focused on the problem qualitatively rather than quantitatively.Extending the previous work to three-dimension, we developed the program for the quantitative calculation of 3-dimensional current distribution using a boundary element method with a linear element of trigonal type. Integrals with singularity from the fundamental solution have been analytically computed and it is shown in detail in the Iiterature11. This paper deals with the three dimensional current distribution for the electrode position of copper in a cubic type cell and the effect of anode shape, size and the distance between electrodes on current distribution is studied."

Jan 1, 1997

By Min Chen, Zhen Tian, Hongxu Cui

"The effects of adjusting technology on the phosphorous enrichment in converter slag were investigated. The results showed that the grain size of 2CaO·SiO2 with high phosphorus containing content increased slightly with the decreasing of cooling rate, and the proper cooling rate was confirmed to be about l.0°C.min-1. Moreover, the morphology of the phosphorus-rich phase of 2CaO·SiO2-3CaO·P2O 5 was changed from granular for the higher basicity of converter slag to the coexistence of granular shape and rod-like for the lower basicity of adjusted slag. With the addition of adjusting agent such as SiO2 to lower the basicity of converter slag, the phosphorus in converter slag could be transferred into 2CaO·Si02 phase effectively, and P2O 5 content in high phosphorus containing phase reached to above 30%.IntroductionThe yield of converter slag is very large in China, but most of the slag is stacked usually after the separation of iron, which not only takes up a lot of land, but also affects the ecological environment seriously. Therefore, improving the comprehensive utilization and value-added products of converter slag is of great significance to recycle the steelmaking slag[l-3]. On the other hand, the refining of hot metal with high phosphorous content is an unavoidable problem with the decreasing of high grade iron ore, and as a result, more amounts of high phosphorus containing steelmaking slag are produced. However, the current recycle of converter slag is more focused on the emission reduction and reuse of steelmaking slag inside the iron and steelmaking process without considering the recycle of phosphorous resources[4-6]. At the same time, the development and utilization of phosphate ore as a strategic resource is drawing more and more attention, but the phosphate ore in China is mostly low grade and significant amounts of tailings are produced which is harmful to the environment. Therefore, it is important to separate phosphorous resources in steelmaking slag which can be used as phosphate ore for fertilizer material[7-9].Literature studies showed that most of the phosphorus in steelmaking slag existing as 2CaO·SiO2-3CaO·P2O 5 solid solution phase in 2CaO·SiO2 particle. The P2O 5 content in the phosphorus containing phase is very low due to the fact that the basicity of converter slag is usually high and the precipitated amounts of 2CaO·SiO2 particles during cooling are very large, resulting in the fact that the P2O 5 contents in 2CaO·SiO2-3CaO·P2O 5 solid solution phase are much lower which is impossible to be used as phosphorous resources instead of phosphate ore. Thus, the enrichment of phosphorus in steelmaking slag is need[ 10-14]."

Jan 1, 2011

By A. F. Usov

"The use of the Electric Pulse Discharge method of materials destruction (EP) for disintegration of materials in an industrial-waste processing are examined. The principles and Experience of the development device of EP-disintegration have been described, the technological efficiency of disintegration of industrial minerals estimated.IntroductionThe Russian scientists have proposed and comprehensively studied the electric pulse (EP) technique which is applied in ores and materials disintegration [1, 2 ]. The different aspects of the problem have been presented by the authors in papers at many international congresses [3-6]. Recently the technique is intensively developed in many countries, and various disintegration installations are exhibited.Crashing and disintegration of ores by EP-method is characterized by high selectiveness of destruction. It provides better disclosure of mineral grains and prevent it from destruction. EPmethod reduces slurry formation. All this provides better mineral extraction at ore beneficiation and improves concentrate quality. It also prevents the product from polluting with equipment metal, inwall and grinding equipment material. The possibility to change the character of dynamic loading allows controlling grain-size composition and getting small-size product in contrast to mechanical method of crashing.The product of EP-crashing is characterized by less toughness and greater specific surface area of grains since the new surface is formed at splitting and chinks extension. The product is of high sorption and reactivity in chemical changes. Open grains of mineral spots correspond to their natural condition and it is of great importance for studying mineral.The principles of the development deviceLong-term studies of the technique carried out by research institutes such as Research Institute of High Voltages (Tomsk), Kola Science Centre of RAS (Apatity), Institute ""Mekhanobr"" (S.Pertersburg), made it possible to substantiate principles of the disintegration installations design, make exploratory stands and technological installations to carry out pilot tests and operations under production conditions. The construction design of disintegrating installations depends on many technological and physical factors. Of all the technological factors, the most significant one is to preserve the liberated product because it is the peculiarity of the EPdisintegration to have high selectivity of disintegration. The preservation of the mono-mineral product liberated from the rock mass means that this product is not overgrinding, which causes the loss of the product with slime in processing, and that the initial natural form of the mineral inclusion is also preserved because it is the size and the integrity of crystals that determines its cost value (precious minerals). On the one hand, it is provided by a stage disintegration technique, with the product classified after each stage, and, on the other hand, by selection of specific conditions of electric breakdown, which ensure high performance of electric breakdown and effective disintegration of material fragments, with the useful mineral inclusions preserved intact, with its size considerably exceeding the discharge gap. These conditions are provided by the appropriate geometry of electrodes, the discharge gap and the screen size due to the material’s nature and grain size."

Jan 1, 2008

By Bernd Kos

The management of waste materials in the aluminum industry is as important as in other basic industries. Due to the high value of the-by products of the melting process and their toxic properties we took the challenge to develop a process technology to reduce the environmental impact and to help industry to get a better yield of their by products/raw materials. In melting operations metal losses due to oxidation are nearly unavoidable, the amount of such losses, however, can be controlled. Aluminum dross actually is a by product and any shop would like to get rid of it in the most economic way. This by product still contains up to 70% valuable metal! In the present work we describe possibilities to separate metal and residues for further processing. Recycling of metal concentrates, selling of dross and dumping of the residues have been the typical solutions up to now. But there are technologies available which are designed to reduce the waste to a minimum or even avoid it altogether. Such alternatives are processing of the dross into materials which can be reused in other industrial processes in order to avoid any dumping. This can be done by separating the metal and the residues by centrifuging and further use of the residues in the chemical or refractory industry. ECOCENT means economical and ecological recovery of aluminum by centrifuging of hot dross. This process, developed by FOCON Austria, is based on the idea of treating the hot dross as quick as possible in a single operation to avoid exothermic losses, intermediate storage and unnecessary handling as well as to save energy. In the ECOCENT process the hot dross is fed without any fluxing salt additions into a converter where the relevant parameters for separation, like temperature and viscosity, will be adjusted. Further big lumps of dross are ground into smaller pieces in order to improve the later separation of the metal. After homogenizing and adjusting the temperature, the hot dross is poured as quickly as possible into a centrifuge. In the ladle or alternatively the mould of the centrifuge the centrifugal forces are used for the separation of aluminum from aluminum oxide, the major constituents of dross. The separated pure metal can either be discharged liquid or as solidified aluminum ring. The design of the device for the production of liquid or solid metal is almost identical. As soon as the centrifuging is finished the liquid aluminum can be poured back into the furnace or can be used for ingot pouring. After the pouring of the metal the "dry" residues are removed just by turning the ladle. Alternatively the aluminum solidifies in the mould and is discharged as a compact ring. The separation of the residues from the aluminum ring is automatic. Due to the batchwise operation the composition of the metal is the same as in the skimmed furnace of origin. The complete treatment cycle needs about 40 minutes. The recovery rate of aluminum is better than 90% of pure metal. This technology is highly flexible by its nature and can easily accomodate various operational requirements. The consumption of energy is more than 50% lower compared to conventional dross processing as the ECOCENT process is using the inherent energy of the hot dross. These extremely good results are not dependent on the aluminum content of the dross even from very dry dross most of the metal can be recovered. The main advantages compared to conventional dross processing are the high recovery rate, the known analysis of the metal and the immediate reuse of the recovered aluminum. The high recovery rate and the pure metal result in a short amortization period. The compact ECOCENT unit needs a minimum of space since extensive handling can be avoided. The electronically controlled process needs no cooling water and is simple, safe and environmentally sound. The residues are free of fluxing salts, their content of metallic aluminum is low and the environmental problems are thus greatly reduced.

Jan 1, 1995

By V. V. Khristenko, V. I. Dubodelov, V. A. Seredenko, B. A. Kyryyevsky, H. V. Seredenko

"During the last decades investigators of many countries shows an increased interest to alloys which are characterized by miscibility gap in a liquid state. It is connected with essential possibilities of control of structurization in such alloys because of the melt at certain temperature parameters is · emulsion with disperse phase inclusions. These ensure essential influence ·on structurizations.The certain inclusions can play a role of lubrication ensuring ""wearless"" process. The sizes of inclusions of this phase can be rather large proportional to sizes of strengthening phase (up to 1000 nm). Other inclusions ensure process of strengthening of a main material. In this case requests to a dispersibility character of distribution and structure of such inclusions are much higher.The multicomponent alloys of system of copper - (Fe - Cr - C)- alloy concern to the number of advanced compositions. The copper alloys with structure of a type of a ""frozen emulsion"" in which strengthening phase· is a chromium pig-iron are characterized by high thermal stability in the extreme operating conditions. The mechanism of inclusions forming is emulsifying of a melt in miscibility gap at temperatures close to temperature of binodal under superimposition of external effects.The main complexity of producing of ware from such alloys is .a providing in their structure of necessary dispersible inclusions uniformly distributed all over the volume. Thanks to a selective action of electromagnetic fields on liquid phases with various electroconductivity relative velocity of phases is created and is regulated the ratio of their ""apparent"" specific gravity is changed. Excitation of pulsing force effects with the certain frequency on interphase surface allow actively to influence on process of a dispersion of a liquid metal medium."

Jan 1, 2000

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By Zheng Wei, Jian Cheni, Zhenliang Weng, Wei Liang, Hongbo Zhu, Jinhui Peng, Linqing Dai, Qianxu Ye

"By testing the dielectric constant and the dielectric loss factor of concentrated Dahongshan, mill scale, anthracite and light-burned dolomite in different frequency and temperature, and by studying the temperature-rising characteristics of the materials in the microwave field of 2.45GHz in frequency, the research in the paper shows that to reach at 1250°C under the same condition -2KW the microwave power and 30g the mass --the time concentrated Dahongshan takes is 330s, whereas the millscale is 855s and the anthracite is 820s. About the last one, the higher the temperature is, the stronger the absorptivity is. After the temperature has rose to 400°C, the anthracite's absorptivity increases dramatically. The result of the research would serve as the foundation of the further study on making direct reduced iron by microwave heating.1. IntroductionUnder the microwave fields, materials' dissipation of dielectric bodies would generate thermal effect. Therefore, the dielectric constant and the dielectric loss factor are closely related to materials' ability of absorbing microwave energy-the larger the dielectric constant and the dielectric loss factor are, the stronger the material's ability of absorbing microwave energy is, and the better the thermal effect would be[1-2]. In order to research how to make reduced iron from iron ore fines by microwave heating deeply and systematically, the test of raw materials' dielectric constants and dielectric loss factors are of the essence. What's more, because a mineral' conductivity is influenced by its components and crystal structure[3], it is necessary to study different materials' different temperature-rising characteristics; hence such studies would provide theoretical foundation of further research."

Jan 1, 2012