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By Takashi Nakamura, Kenji Oosumi, Kazuhisa Fujisawa, Takayuki Kogishi

"Recycling of used aluminum beverage cans(UBCs) is one of the important issues for aluminum manufacturer presently. The direct re-melting of UBCs shows two problems. One is a reduction in molten aluminum recovery and the other is a contamination of other metals such as Ti and Fe from paints. Both problems are caused by paints coated on the surfaces of aluminum cans. Removal technique of the paints, therefore, has been required. Although roasting and shot blast techniques have been developed, both were not successful in removing the paints effectively. A swell-peeling method has been applied to remove them using a methylene chloride solution with acids and it works very well. Small laboratory scale tests have been carried out to develop the commercial process and clarify the mechanism of the swell-peeling method in the present study.When the surface area of UBC is more than 10 cm2, peeling time is independent of the surface area, about 60 seconds, because swelling phenomenon is controlled by the penetration of the liquid through the fine pits on the surface of the paint. This is good for a commercial process. Peeling takes place when the swelling force generated by methylene chloride exceeds the adhesion force between the film and the surface of aluminum, that is weakened by the coexisting acid, especially halogenated acetic acid."

Jan 1, 2000

By T. V. Jayaraman, D. Das, B. Mallesham, A. R. James

The PNN-PZT xPb(Ni0.3Nb0.67)03-(1-x)Pb(Zr0.31 Ti0 69)03 (0.2=x=0.6) based relaxor-ferroelectric material was synthesized by colurnbite precursor (NiNb206) method via conventional solid state reaction. Homogeneous mixture of required oxides and precursor was calcined at 850°C for 4 hrs to obtain phase pure perovskite. Pellets of PNN-PZT ceramics were sintered at 1100oC for 4 hrs. Phase pure perovskite structure was confirmed by the X-ray diffraction analysis. From the X-ray diffraction analysis it is also confirmed that there is a structural transformation from the rhombohedral to tetragonal with increase in PZT content and existence of morphotrophic phase boundary (MPB) at x = 0.5 composition. The morphology and microstructure of the sintered pellets were observed using the scanning electron microscope. P-E loop measurement shows the high remnant polarization (19.12 µC/cm2) and low coercive field (6.89 kV/cm) at MPB compared to all other compositions. The electromechanical planar coupling coefficient (kp) was measured through the resonance and anti-resonance method using the LCR meter. The piezoelectric strain coefficient (d33) measured directly using the d33-meter. At x = 0.5 composition the highest value of d33 = 398 pC/N is obtained.

Jan 1, 2012

By Jakub Kaczorowski

In the production of Mn-alloys, the Boudouard reaction significantly influences the mass and energy balance. The endothermic nature of this reaction requires more energy for the process, while the direct consumption of carbon is reflected in the greater demand for carbonaceous raw materials. Therefore, it is desirable to eliminate or suppress the reaction. The kinetics of the Boudouard reaction are a function of many factors, of which coke properties and the conditions around the particles (i.e. temperature, gas composition) seem to be the most important. In the present study properties of selected single source and commercial metallurgical cokes are compared with reactivity results. The single source cokes represent a single coal that has been carbonized in a laboratory scale furnace. The commercial cokes are products of carbonization of coal blends under industrial conditions. The coke properties include proximate, ultimate and ash analysis. Also, coke petrography with carbon forms is included. The reactivity tests were performed on different particle sizes at various temperatures, gas compositions and gas flow rates. The experimental parameters were chosen to simulate the conditions in an industrial furnace. The results show that highly graphitized structure of cokes, minimal surface area and a low concentration of ash retard the reactivity. Of the other factors, the temperature and the gas composition have the greatest impact on the reactivity.

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 John B. Dale

A primary objective of copper mining, smelting and refining operations is the cost- effective, efficient, and environmentally-acceptable control of the level of various metal ions throughout the processing and effluent treatment flowsheets. Effective ionic control maximizes product and by-product quality, allows for broad flexibility in sourcing impurity laden ores, minimizes capital and operating costs, and can achieve zero discharge operations. In order to meet increasingly stringent cost, environmental and product quality requirements, separation technologies are needed that can selectively remove and recover deleterious or valuable ions. Ideally, the subsequently obtained salts or metals can be recycled in the process, disposed of in an environmentally acceptable manner, or sold as valuable by-products. The use of MRT, a highly selective separations technology, has been demonstrated to be a cost effective, efficient, and environmentally- sound treatment for a wide range of cations and anions that are commonly found in copper electrorefining and electrowinning circuits, as well as in environmental treatment operations. These include heavy and transition metals, precious metals, halides and alkali/alkaline earths. This paper will review a number of areas of interest including: recovery and refining of platinum group metals from copper anode slimes, recovery of copper from acid mine drainage streams, extraction of Bi, Sb and C1 from copper electrorefining and electrowinning circuits.

Jan 1, 1999

By Jitka Jandová

In this study, hydrometallurgical processing of waste ZnO flue dust arising during zinc removal from galvanized low-alloy steel sheets was investigated on a laboratory-scale to obtain electrolytic zinc. The flue dust was separated from flue gases, generated during heating waste galvanized steel sheets in an electric furnace under air atmosphere at temperatures of about 1000oC. The dust, comprising tetragonal ZnO and insignificant amounts of SiO2, was contaminated by Fe, Mn, Pb, Al, Mg, Pb, Cu and Ca. The dust was leached in 0.5 and 1.0M H2SO4 and/or in 20 and 30% NaOH at different temperatures and different liquid-to-solid ratios to determine the optimum conditions leading to the highest possible selectivity of leaching and efficiency of Zn extraction in minimum time. The subsequent electrowinning process was performed with refined zinc sulphate leach liquors and/or with untreated zinc caustic solutions. Zinc sulphate leach liquors were purified using a combination of a hydrolytic pH-controlled precipitation, cementation and carbon refining. Effects of operational variables on Zn electrowinning have been studied for both sulphate and caustic electrolytes. The conventional plate-plate electrowinning cell has been explored in this study. Comparison of results obtained for both zinc electrowinning from acid sulphate and alkaline solutions is presented contribution.

Jan 1, 2003

By C. O. Bounds

The magnetic properties of (NdDy)15Fe78B6 sintered magnets have been evaluated using powder prepared by Inert gas atomization. The atomized powder had a particle size distribution from 1 to approximate 1000 microns. The as atomized powders have been sieved into, coarse, intermediate, and fine fractions; magnetic properties were evaluated for the as produced powder and each fraction. A B, of 11.7 kG, a Hci of 11.0 kOe and a BHmax of 32.5 MGOe was -obtained on a sintered magnet made from the as-atomized powder. The magnet made from coarse powder exhibited a slightly higher B, of 12.1 kG, while that from fine powder showed a decrease in B, to 11.2 kG. Hydrogen decrepitation has been utilized to study its effect on the magnetic properties. Finally, cast ingots with a definite columnar structure have also been used to compare the magnetic properties of magnets of the same nominal, composition but of different alloy preparation process. Hydrogen decrepitation does not appear to improve the magnetic properties of magnets made from thin cast ingots. However, it does show a significant improvement in the Hci of magnets made from the atomized powders. Possible causes for the differences in the magnetic properties on magnets made from each process have been discussed in the paper.

Jan 1, 1992

By Fernando Guevara

Many smelting and slag-cleaning furnaces operate with cooling systems designed to freeze a slag layer over the refractory to protect it. The fluid flow and heat transfer conditions associated with the freeze layer and mushy zones are poorly understood. These phenomena were simulated with a small-scale room temperature, 2-dimensional model, using an aqueous solution of calcium chloride to simulate the slag. Reasonable similarity with conditions encountered with copper and nickel smelting systems was achieved (Pr 50 and Ra 108, in the laminar-turbulent transition). Measurements of the freeze layer development and velocities were made with the Particle Image Velocimetry (PIV) technique. Direct Numerical Simulations (DNS) were also made of the unsteady fluid flow and heat transfer problem. It was found that the solidification process is well described using an improved model for high molecular viscosity in the mushy zone. Solid front growth, isothermal profiles, velocity profiles and heat transfer through the walls showed good agreement between the PIV and DNS results. Experimental and numerical velocity profiles close to the freeze layer show a parabolic behaviour in the vertical velocity profile which is completely different from the calculation of heat transfer using a sharp interface model. The reason for this is attributed to the effects of the mushy zone with a high viscosity and high shear stresses acting on that area.

Jan 1, 2006

By I. Barin, G. Eriksson, F. Sauert

Computer-aided calculations using data bases and program systems are more and more needed for the rational development and optirnization of high-temperature processes. The calculation of mass and energy fluxes between different process steps as well as the determination of the chemical equilibria will be discussed, giving examples from nonferrous metallurgy. The simulation of a waste-material treatment process including high-temperature combustion and gas-cleaning systems will also be demonstrated.

Jan 1, 1988

By Richard Krentz

Two separate on-line analyzers are operated at the Corefco metals refinery. The first application is an on-line refractometer which measures the ammonium sulphate concentration in the primary feed slurry tank. The second application is a multi-stream X-Ray fluorescence analyzer which measures the metals and sulphur concentrations in eight key refinery streams. Specific applications of the on-line analyzers with advanced control systems for improved process control will be discussed.

Jan 1, 2003

By Olga A. Gomon, Alexey N. Lozhko

The technology of heat treatment for metal frequently includes multiple fast heating and cooling of the products surface. If the product is heavy-weight or long-size, its moving from a zone of cooling to a zone of heating and return require a long time. Other important condition of ensuring qualitative surface at heat treatment is intensification of cooling phase. It is known that turbulization of a flow activates heat exchange and increases efficacy of cooling without increasing volume flow rate of water. Additional difficulty is to ensure the regularity of heating and cooling on length of a product. The technology of cyclic heat treatment of rolling products, at which mobile zone of turbulent heat exchange is formed on the surface of a product, was developed and realized. The submission of water occurs through to face spray systems. Each of the systems has six long-range atomizers, which are located circularly. Two flows of water move towards one another along a surface of a product. When they collide, the right zone of turbulent heat exchange creates heat transfer in this zone of 10-15 time more intensive than on other surface of a product. The effect of moving turbulent zone on length of a product is reached by changing the proportion of volume flow rate of water, which is created by face sprays. The speed of movement for turbulent zone along a surface of a product is chosen so, that the cooling takes place on a small depth only. Then after passing the turbulent zone over a determined site of a surface, its temperature recovers fast owing to hot internal layers. The parameters of process were determined by mathematical simulation of cooling in an installation. The equations for dynamics of movement of collision point of flows, which were received this way, are interesting supplementary products of research. The experiments show that frequency of movement of turbulent zone is an important technological parameter. It defines mechanical properties of a surface and should be chosen depending on a profile of product and metal grade. The results of comparison of mechanical properties of a surface of various rolling products, which were received by developed and conventional technologies, are described in this report. Dependence of regularity of mechanical properties on frequency of movement of turbulent zone is adduced.

Jan 1, 1998

By Z. Zhang, Zongshu Zou, Nan Wang

"Thermodynamic calculation is applied to make an investigation on the equilibrium phase relations and liquids of CaO-SiO2-Al2O3-FeOx system for different temperatures. The calculated results with FactSage6.1 show that the effect of temperature on the the equilibrium phase relations and liquidus of CaO-SiO2-Al2O3-FeOx system and its sub-systems is appreciable. The liquid phase regions enlarge with increasing temperature from 1573K to 1873K, while the primary phase fields reduce distinctly.IntroductionThe main oxide components of vitrified bottom ash slag are CaO, Al2O3, SiO2, Fe2O3, MgO, and Na2O, accounting for more than 90% of the bottom ash by weight[1]. During slag processing, the knowledge of thermodynamic properties and liquidus temperature in the related slag systems is highly required [2, 3], which is not yet available. Through literature survey [4-6], it is clear that the systematic information on the concerned complex slag system is scarce. So far the engineers in the field have to make assumptions of the thermodynamic properties of the simplified oxide system, without taking into consideration the interactions of the different oxide components, which hinders the development of the slag valorization and utilization. In order to provide thermodynamic properties for the application of the vitrified bottom ash, the six-component oxide system (CaO-MgO-Al2O3-SiO2-FeOx-Na2O) is highly required. A preliminary phase diagram of the CaO-MgO-Al2O3-SiO2-FeOx-Na2O system can be obtained from extrapolation of the thermodynamic functions of constituent subsystems such as CaO-SiO2-FeOx-MgO, CaO-SiO2-FeOx-Al2O3, CaO-SiO2-Na2O-MgO and CaO-SiO2-Na2O-Al2O3. In this work, the equilibrium phase relation and liquidus of CaO-SiO2-FeOx-Al2O3 system, one subsystem of the concerned complex slag system, are calculated and the effect of temperature is also discussed."

Jan 1, 2012

By Tugba Basargan Çagatay Morall, Gülhayat Nasun-Saygili

"The aim of this study is to prepare the apatitic material using colemanite mineral (2CaO.3B2O3.5H2O) which was obtained from Eastern Anatolia, Turkey. For this purpose, colemanite mineral was reacted with different phosphate sources, namely, dipotassiumhydrogen phosphate, ammoniumhydrogen phosphate and ortophosphoric acid at various temperatures and time periods. Experiments were run in batch system. The apatitic material was prepared by a wet method and followed by heat treatment at various temperatures. Structure of the samples was analyzed by XRD, FTIR, XRF and SEM. The particle size analysis was also made for the result product. The experiments showed that reaction temperature, contact time and heating temperature are important parameters to transform the colemanite into apatitic structure. Reaction of colemanite with dipotassiumhydrogen phosphate and ammoniumhydrogen phosphate results in amorphous, non-stoichiometric hydroxyapatite type structure, while acid based phosphate source gives brushite and monetite type product before and after heat treatment, respectively.IntroductionBoron which has properties intermediate between metals and non-metals is a member of semiconductor group of elements. Its atom is very small and has three valence electrons. Boron exists in Earth's crust (from 5 mg/kg in basalts to 100 mg/kg in shale) and in the oceans (4.5 mg/l) [1]. Turkey has 60% of world's boron reserves which is mostly in the form of colemanite (2Ca0.3B203.5H20). Colemanite is the most important calcium containing commercial borate mineral with 5 mol of crystal water [2].Calcium phosphate cements are very useful for bone repair applications because of its chemical structure. They are injectable, easy to shape and can be maintained locally. Because of those reasons calcium phosphate cements are very effective to fill bone defects with an irregular shape [3]. Hydroxyapatite (Ca10(PO)6(OHh) is the major component of the bone (70 wt%). However, hydroxyapatite stoichiometry, composition and crystallinity differ in human skeleton system [4, 5].The main objective of the present work was to study the transformation of colemanite to apatitic material using different phosphate solutions at several time spans and temperatures. The experiments were run in a batch system, change in pH and also weight loss were measured after the experiments. Several analysis methods were used to investigate the chemical and structural changes."

Jan 1, 2012

By Cheng Gong-jin, Chu Man-sheng, Liu Zheng-gen, Zhang Yong, Liu Jian-xing, Xue Xiang-xin

"High chromium vanadium-titanium magnetite is one kind of Fe-V-Ti-Cr composite ore resources, which owes high utilization value. Owing to lacking systematic study on the sintering of this ore home and abroad, effects of carbon addition and basicity on sintering process and sinter metallurgical properties, such as sinter yield, vertical sintering speed, tumbler strength, sinter machine utilization coefficient, and low temperature reduction degradation were investigated systematically under laboratory conditions in the paper. The results shows that, when high chromium vanadium-titanium magnetite proportion is kept unchanged as 13% in sintering feeds, sintering process index and metallurgical properties are the optimum under carbon addition 5.0% and basicity 2.70, which meets the requirements of blast furnace burdens. This research provides technical parameters for practical sintering production of high chromium vanadium-titanium magnetite.IntroductionHigh chromium vanadium-titanium magnetite (hereinafter abbreviated as hi§h-Cr V-Ti magnetite), in which Fe is closely symbiotic with Ti and isomorphous with V and Cr1'- l, is one kind of typical vanadium-titanium magnetite resources with high comprehensive utilization value but the difficulties are extremely high due to complex chemical composition and mineral structure. At present, the feasible and mainstream utilization process of high-Cr V-Ti magnetite should be the route of agglomeration-blast furnace smelting. Thus, sintering production is the foundation for high-Cr V-Ti magnetite utilization. However, till now there are few research documentations on high-Cr V-Ti magnetite sintering home and abroad. Under the above background, this study focused on detailed researches of high-Cr V-Ti magnetite sintering. Sintering process uses the powders or fine iron ores to produce artificial rich ore with good metallurgical properties 4l Solid fuel provides 90% heat requirement during sintering15J. The appropriate amount of fuel and flux should be added during sintering in order to provide necessary heat and maintain the desired basicity16l. That is to say, carbon addition and basicity are two key factors affecting metallurgical properties of sintering products17J. Therefore, the effects of carbon addition and basicity on sintering process and metallurgical properties, including sinter yield, vertical sintering speed, tumbler strength, sinter machine utilization coefficient, and low temperature reduction degradation, are systemically investigated under laboratory conditions in the study, on purpose to achieve the optimization of sintering process for high-Cr V-Ti magnetite."

Jan 1, 2013

By T. J. A. Smith

This paper provides an overview of some of the key issues in design of smelter gas handling systems, with particular reference to sulphide smelting plants. In both primary smelting and converting. gas handling and treatment systems often represent the major capital cost component. There is also ample evidence that poor system design can be a major cause of smelter down time, lost production and unforeseen high maintenance costs. The paper discusses these issues and offers guidance for improved design.

Jan 1, 1992

By Susumu Okabe

Top blowing lances are employed by the Mitsubishi Continuous Copper Converter for the continuous supply Of reaction gases into moken bath. In order to minimize the refractory wear caused by the interaction between the furnace lining and the melt splash. optimum furnace design and blowing condition are? required. An empirical equation obtained by the physical model study enables the estimation of the splashing rate on a vel1ical plane at a certain distance from the lance.

Jan 1, 1996

By T. R. A. Davey

It is often important in the study of a process to determine whether the limitations are governed by equilibrium or kinetic considerations. Sometimes it is possible to devise a design of the process or the equipment so that the apparent. limitations set by equilibrium considerations are overcome. In this paper, detailed consideration is given to the lead refining processes of sulfiir-decoppering and of vacuum dezincing to illustrate this, and possible implications for other refining processes are indicated.

Jan 1, 2000

By KNona C. Liddell

The time and spatial dependence of component and species concentrations during in situ uraninite leaching have been modeled using a reactive transport model based on partial equilibrium between reactive minerals and the solution. The flow field is represented by mixing cells in series. The effects of the H2O2, (NH4)2CO3, and NH4HCO3 component concentrations have been simulated, and results are presented for a one-dimensional flow field.

Jan 1, 1995

By Sergio Demetrio

Over a period of nearly a hundred years throughout this century, the company direction and management of copper smelters in Chile has evolved from one characteristised by a paternalistic, autocratic style to one which empowers the local management team and people for running the smelter as a successful business. This paper discusses the evolution of the present style of management amidst changes in the Chilean Government, the mining industry and society since the beginning of this century.

Jan 1, 1999

By H. Aminian

Copper electrowinning (EW) is an important process in connection with the solvent extraction to produce pure and marketable copper cathodes. A phenomenological model was developed to simulate the copper electrowinning process. The simulator is used to predict the operation of the Mines Gaspe pilot plant electrowinning cells put in operation in 1996. Results confirm the potential of the simulator that would subsequently be used for student training, process optimization and assessing the performances of control strategies.

Jan 1, 1999