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By P. K. Narasimhargahavan

This paper discusses briefly the major reasons associated with the growth and its impact on the energy requirement and Environmental imbalance. A projection based on the present global Alumina and Al requirement indicate a substantial further growth of at least 30% over the next 10 years. It is indicated that the main factors which are likely to influence investments are the environmental factors such as the Climate Change and global response to the growing energy prices and sustainable development. Each of the developed / developing nations must find response to the GHG emissions which will encourage the Al Industry to make an effective contribution to global warming while preserving the international competitiveness of the industry - a challenging task. The efforts shall concentrate on improving energy efficiency in the industry possibly of the order of 25% over the next 10 to 20 years. The developments in this line are discussed.

Jan 1, 2010

By Kurt Svens

"As zinc consumption is gradually increasing all the time in the world, many zinc plants are looking for possible expansions. As the sulphuric acid market as well as the fertilizer market in many areas is saturated, the costs for the roasting-acid plant section of the zinc plant will create problems when making feasibility calculations for possible expansions. For solving the customers' situation, two proven zinc concentrate direct leaching technologies are available. A third one, which is possible, does not have any industrially proven applications in the zinc area.IntroductionTime to time, the zinc plants in the world scrutinize their operations with respect to their cost efficiency, the total zinc recovery and the near-by or far-away consumer markets, especially the for zinc and sulphuric acid. Their preliminary profitability calculations can show that a possible total expansion is not economical, when they are looking to expand the whole roasting/acid plant - leaching - solution purification - electrowinning - casting route, as the possible market price for the sulphuric acid is low or the sulphuric acid market is too far away. Based on these facts, their economical study often indicates that implementing a zinc concentrate direct leaching option could be more favourable. Regarding this situation, several aspects concerning three alternative direct leaching methods will be discussed, of which pressure leaching and the atmospheric leaching processes have several industrial applications in the zinc industry, as the ultrafine grinding - conventional leaching process at present has none. As iron is also dissolved during zinc concentrate direct leaching, iron removal processes generally used in the zinc industry are additionally discussed below."

Jan 1, 2012

By Steven Wright

The reduction of a slag produced 6om the recycling of lead batteries was studied in a kilogram scale laboratory investigation by reacting with graphite at temperatures of 1180 and 1200°C. Simultaneous reduction of PbO, Fe203, Sb203 and As203 occurred with the Sb and As reporting to the metal while the lead content in the slag was above 2 wt%. The Sb and As distributions between metal and slag were strongly affected by temperature and slag oxidation state. The rates of reduction of PbO and Sb203 increased with increasing slag basicity and temperature and decreased as the PbO content in the slag decreased. The reduction rate of PbO from these slags was similar to other industrial lead slags at the same CaO/SiO2 ratio and temperature. The implications of the behavioural similarities of the antimonous slags during reduction with carbonaceous reductants and other lead slags are briefly discussed.

Jan 1, 1994

By R. G. Hilton

This paper deals with application of Super Detox? stabilization technology to the treatment of electric arc furnace dust (US-EPA listed hazardous waste KO61 ). The process has been used on approximately 170,000 tons of electric arc furnace dust. In addition to the nearly four years of commercial experience at Sterling, Illinois, the process is now being permitted for application at two other locations. The process was originally developed by the Bethlehem Steel Corporation and then further improved by Conversion Systems, Inc. (Bethlehem Steel's Licensee). The treatment process offers many unique bases for its selection, including: A) Low cost compared to the treatment alternatives; B) Lowest available TCLP leachate levels for any process treating K061. Many other processes leave some residue that represents a disposal requirement, although often not addressed; C) Produces minimized final waste disposed, including the fact that the total volume of dust generated and less than the volume occupied by the residue slag from HTMR; and, D) Opportunities for the beneficial utilization of part or all of the waste stream through the development of chemical and physical characteristics. Each of these aspects will be specifically discussed in the paper, including that status of the operations now under permit.

Jan 1, 1994

By Akira Kaneda

Mitsubishi continuous process employs an electric furnace for settling matte from slag. Electrodes are immersed into the slag layer in the slag-cleaning furnace and the temperature of the melt is maintained at a predetermined level by Joule's heat. Electrodes are immersed to the depth where the current of each electrode is kept at a set value, and they are raised or lowered automatically to compensate for the deviation from it. Because electric resistance of the bath is varied with the matte level in the furnace and the composition and temperature of the slag, the immersion depth of the electrodes is affected by them. Therefore by monitoring the immersion depth and its change with time, abnormal situations in the furnace, such a~ rise of matte level or local abnormal state of melt, can be detected. In this paper, relations between state of the furnace and electrode behavior are discussed based on the plant data, and then a new and simple monitoring method of the condition of the furnace is proposed.

Jan 1, 2001

By C. A. Pickles

At the present time, pyrometallurgical processes are employed for the recovery of lead from battery scrap. These processes have serious pollution problems, primarily due to the emfssion of sulphur dioxide and airborne lead in the form of dust and fume. In addition it is necessary to dispose of solid wastes and liquid effluents which contain lead and in some cases sodium sulfide-containing compounds. In this work an improved process was investigated for the recovery of lead from battery residue. This involved pelletization of the residue with sodium carbonate and moisture. Then, the pellets were melted without carbon and the .sodium sulphate salt was removed. Subsequently, the molten lead oxide was reduced with carbon. This process minimizes the sulphur dioxide emissions and leads to very low sulfide contents of the sodium sulfate salt

Jan 1, 1992

By V. Montenegro

Smelting of copper concentrates in Teniente Converter produces highly oxidized slag, containing from 4 to 10 % Cu and from 15 to 25 % of Fe304. Copper recovery requires magnetite reduction at a level of 5%, determining the degree of cuprous oxide co-reduction and the liberation of copper matte inclusions. The rate of slag reduction is controlled by the mass transfer to the reaction interface. Slag stirring affects the rate of reduction and enhances coalescence of mechanically entrained copper matte inclusions. Slag reduction and sedimentation in the AC electric furnace is a commonly used method of slag cleaning. Utilization of DC electric furnace creates beneficial conditions introducing slag electrolysis additionally to chemical reductions with carbon of coke and electrodes. Application of external magnetic field, interacting with a direct current in an electric furnace, induces magnetohydrodynamic phenomena, such as intensive stirring and electromagnetic buoyancy force acting on inclusions. Laboratory scale research in simulated DC electric furnace with a superimposed magnetic field showed a significant acceleration of the rate of slag reduction and copper removal. Continuous measurement of gas flow and composition allowed for determination of the reduction rate along the time. Application of external magnetic field in the reduction of the industrial slag in a crucible simulated DC electric furnace results such as the increase of the reduction rate from 2 to 3 times, compared with the identical conditions in the AC electric furnace. Interaction of non- homogeneous electric field with crossed permanent magnetic field induces vigorous slag stirring, enhance mass transfer and accelerate the rate of the slag reduction. Additional participations of the slag electrolysis in the magnetite and cuprous oxide reduction as well as the acceleration of the settling of the inclusions by the electromagnetic buoyancy force affect the slag cleaning intensification.

Jan 1, 2003

By Luiz A. Teixeira

This paper reports the results of kinetic studies involving the precipitation of arsenic from aqueous solutions as FeAs041 Fe(OH)3' using FeS04 as source of Fe ions, and Air or H202 as oxidizing agents. Both systems lead to an efficient removal of arsenic. The differences in oxidants performances are in the precipitation reaction rate -much faster using hydrogen peroxide. Mechanisms of reactions were suggested based on the following main steps:

Jan 1, 1996

By Michael E. Stout

The recovery of the constituent components of spent lead acid batteries was pioneered in the early 1970's by M.A. Industries, Inc. MA's main reason for research and development in this area was to recover the polypropylene casings for use as feed stock in their injection molding plants. At that time spent and reject casings were either disposed of or being fed with the lead 'bearing materials into the ,smelting process. M.A. has since developed, built and operated plant for the conversion of scrap casing into reusable copolymer resins. The system is composed, of washing, .sizing, extrusion and pelletizing the polymer into a form which is ready to be injection molded into new products.

Jan 1, 1995

By E. Legault-Seguin

The current industrial practice in the processing of nickeliferous laterites involves the precipitation and releaching of Ni and Co to allow separation from the major impurities of Mn, Mg and Ca. A direct solvent extraction process has significant advantages over this practice, which suffers from difficult and costly precipitation steps, lower recovery and inherently complex flowsheets. The present investigation involves the examination of Cyanex 272, Cyanex 301 and Cyanex 302 as extractants for the direct extraction of Ni and Co from major impurities associated with laterite leaching, i.e. Mn, Mg and Ca. For Co extraction, Cyanex 301 and Cyanex 302 are superior to Cyanex 272, because they are able to selectively separate Co from Mn, Mg and Ca. Cyanex 272 offers complete extraction of Co from Ni and Ca, but Mn and Mg pose difficulty. Ni can only be extracted selectively with Cyanex 301, thus another extractant selective for Ni, such as Versatic 10 or Cyanex 301, is needed to recover Ni if Cyanex 302 or Cyanex 272 is used for the initial extraction.

Jan 1, 2004

By Katsutoshi Inoue, Shafiq Alam

Several novel types of chemically modified chitosan were prepared by immobilizing functional groups of EDTA and DTPA onto polymer matrices of chitosan in order to investigate their potential for mutual adsorptive separation among rare earths. Following the batch wise adsorption tests to elucidate their basic adsorption characteristics for rare earths, mutual separation was carried out using a column packed with the chemically modified chitosan. The separation between Sm(III) and Y(III) was tested using a column packed with EDTA-type chitosan while mutual separation among 4 light rare earths, La(III), Ce(III), Pr(III) and Nd(III) was tested using a column packed with DTPA-type chitosan. In both cases, satisfactory mutual separation was achieved by the chromatographic operation using these chemically modified chitosan.

Jan 1, 2014

By Eric J. Grimsey

Steady state Excel models for a copper flash smelter and an iron blast furnace are used to enhance the teaching of pyrometallurgical smelting principles within a fourth year level process engineering unit delivered at the Western Australian School of Mines. A lecture/workshop approach has been adopted in which student teams undertake process simulation assignments that illustrate the multifaceted responses of process outputs to variation of inputs, the objectives being to reinforce their understanding of smelting principles. The approach has proven to be popular with students, as evidenced by the consistently high ratings the unit has received through student feedback. This paper provides an overview of the teaching approach and process models used.

Jan 1, 2014

By G. Taylor, S. Bounds, G. Moran, M. Cross, K. Pericleous

"A variety of interacting complex phenomena takes place during the casting of metallic components. Here molten metal is poured into a mould cavity where it flows, cools, solidifies and then deforms in its solid state. As the metal cools, thermal gradients will promote thermal convection which will redistribute the heat around the component (usually from feeders or risers) towards the solidification front and mushy zone. Also, as the evolving solid regions of the cast component deform they will form gap at the cast-mould interface. This gap may change the rate of solidification in certain parts the casting, hence affecting the manner in which the cast component solidifies. Interaction between a cast component and its surrounding mould will also govern stress magnitudes in both the cast and mould - these may lead to defects such as cracks.This paper presents a multiphysics modelling approach to this complex process. Emphasis will be placed on the interacting phenomena taking place during the process and the modelling strategy used. Comparisons with plant data are also be given."

Jan 1, 1999

By S. Malinov, J. J. McKeown, W. Sha, S. McShane

"A model is developed for prediction of fatigue stress life S-N diagrams for Ti-6Al-4V alloy at different conditions, using Artificial Neural Network (ANN). Different factors which have influence on the S-N diagram are involved as input parameters of the NN, namely microstructure, environment, texture, test/work temperature, surface treatment and stress amplitude. As the output the S-N fatigue diagram is simulated and plotted.The model is based on standard multilayer feedforward neural network. The NN is trained with a comprehensive data set collected from the literature, using Levenberg-Marquardt training algorithm in combination with Bayesian regularisation. A very good performance of the trained Neural Network is achieved. Good correspondence between ANN"" prediction and experimental S-N diagrams is observed. Using the model S-N diagrams for different conditions are predicted and analysed. Graphical User Interface is developed for use of the model. We believe that the model will be important for practical applications in solving various problems on fatigue behaviour of the titanium alloy.IntroductionTitanium and its alloys have an increasing range of applications due to their very good combination of mechanical properties, corrosion and erosion resistance. They are currently finding widespread applications in many industries due to their desirable and versatile properties. Most important among the alloys is Ti-6AI-4Y. Jet aircraft manufacturers are the principal 'consumers of Ti-6Al-4V and it is often specified for critical parts, the failure of which could result in the loss of an entire system. A generic class of Ti-6AI-4V has been developed over the past years and it has become the best understood of all the titanium alloys. The advantages of titanium alloys include: (i) low densities, giving very attractive strength to weight ratios allowing lighter and stronger structures; (ii) superior corrosion and erosion resistance in many environments; (iii) high temperature capability. Although the titanium materials are still considered as expensive materials, for many applications the cost of titanium alloys can be justified on the basis of their desirable properties."

Jan 1, 2001

By Vince Newberry

Alcan Rolled Products at Oswego, New York, commissioned Recycle II during May of 1995. Recycle II is an advanced technology UBC recycling facility designed to meet the most stringent environmental standards enforced to date in the United States, particularly with respect to NO, and particulate emissions. This paper addresses the exacting requirements and strategies of Alcan's Recycle II project andThorpe Technologies' design considerations and solutions for the supply of environmentally favorable melting furnace and delacquering systems. The furnaces are equipped with low NOx regenerative burners and furnace pressure and hearth gas flow controls designed specifically for processing the hearth gases through baghouses. The delacquering system is a new generation Apros concurrent flow unit designed for low NOx emissions.

Jan 1, 1995

By Ignacy A. Lipiec

The advantage of microorganisms used in bioleach systems to conventional chemical reaction systems is that these apply the available energy more precisely where it is needed, either directly onto the mineral of interest or by efficiently catalyzing the production of a reactant. The literature cover the range from empirical models used in describing macro heat balance in heaps to detailed studies relating the micro heat effects of bacteria adhesion energy to the surface of minerals. In this paper, the heat effects are reviewed in a general way describing bioleaching in two macro systems, heap leaching and slurry bioreactors. The micro scale heat effects is the reactions and conditions at the microorganism scale, including the mechanism of leaching and bacterial behavior.

Jan 1, 1998

By Richard D. Hagni

Reflected light microscopy is routinely applied to the study of ore minerals and textures in polished sections prepared from a wide variety of ore specimens. With the increasing interest in environmental problems, the important role of the reflected light microscope in the precise phase identifications and the determination of the textural relationships between those phases needs to be recognized. Among other environmental applications, the microscope has been applied to the recognition of lead smelter particles from remote collect sites in Missouri and those particles have been compared to dust particles from specific localities at the nearby lead sinter plant and lead blast furnace. Dust from a secondary copper refinery has been studied for its mineralogy. Soils in the vicinity of a Missouri lead smelter have been studied for their mineralogy in preparation to the clean up of those soils. Electric arc furnace (EAF) dusts, recently classified as hazardous waste by the EPA, have been examined for their mineralogy and textural intergrowth in order to better evaluate proposed metallurgical treatment procedures to render the dust non-hazardous. The initial products from experimental metallurgical treatment of EAF dusts also have been studied to aid in determining the effectiveness of those treatment procedures. Refractory gold sulfides that have been roasted in the presence of lime to retain environmental objectionable sulfur and arsenic while recovering the gold have been studied by RLM to determine their mineralogy, porosity, and permeability for cyanide leach solutions. These case histories illustrate the applicability of ore microscopy to the study of problems related to environmental concerns.

Jan 1, 1995

By R. Boom, C. F. Balentina, J. H. L. Voncken

During vitrification of bottom ash generated from the combustion of municipal solid waste (MSW), a Fe-Cu based alloy phase with great value was formed. In order to find proper commercial use in metallurgical industry, it is necessary to separate Cu and Fe. The present study focuses on the sulfide treatment at temperatures of 1400 – 1500oC, in particular with FeS containing minerals. Various sulfide compounds such as Na2S, Al2S3 and Ni3S2 were added to promote the copper removal. Pyrite and zinc sludge (containing ZnS) as waste streams were studied with specific interests. The results showed that both zinc sludge and pyrite are effective for copper removal with the highest removal efficiency of 95% by using pyrite. The copper content drops from 12 wt% to about 2 wt%. However, it is still difficult to remove copper completely from the alloy in one step, and a multi-step operation is needed.

Jan 1, 2008

By Chi-Ming Chang

Alloy powders are commonly used in the purification of zinc sulfate solutions for use in standard electrowinning practice. The primary goal of this research was to study the use of zinc-lead alloys for similar reactions in the galvanic stripping of impurities from organic solutions. The effects of various parameters on the electrochemical behavior of commercially produced zinc-lead alloy powders were determined. A qualitative evaluation and summary of the influence of the more pertinent parameters on iron removal from di-(2-ethylhexyl) phosphoric acid (D2EHPA) by galvanic stripping is given. Water concentration, oxygen content and reaction temperature were the principal factors affecting the reaction rate and process efficiency. Activation energies were also calculated and indicated that the reaction changes from chemical to diffusion control .with increasing temperature in the range of 35" to 45°C. The results showed that zinc-lead alloy gave faster reaction rates with less sensitivity to process variables than SHG zinc as a reducing agent for galvanic stripping. The role of lead could be as cathodic sites for the reaction which enhances the zinc dissolution or anodic half reaction. The morphology of the zinc-lead alloy surfaces, before and after the reactions, supports this assumption.

Jan 1, 1998

By Lisa E. Helberg

"Titanium tetrachloride is produced through the chlorination of a variety of titanium bearing ores, some occurring in nature, and others enriched in titanium content by a variety of ""beneficiation"" processes. The chlorination step can produce a variety of metal chloride impurities, such as iron chlorides and vanadium chlorides, which must be removed from the TiC14 before it can be used to produce pigmentary TiO2, titanium metal or for any other commercial use. The requisite manipulations involve both physical and chemical separations in a multi-step process. The history of various purification strategies will be discussed.TextThere are a wide range of titanium-based products available, all of which start with titanoferrous ore of some type. Two main routes are used to convert ores into products, known as the sulfate and chloride processes. The sulfate process uses sulfuric acid to digest the ore, separate the impurities, and then precipitate titanium dioxide from the resulting titanyl sulfate (TiOSO4) via metatitanic acid. This process can also supply TiOS04 for other applications."

Jan 1, 2011