Search Documents

By M. Giunti, R. Hampson, S. Gray, P. Kapoulitsas, J. Clark

In 1997 Pasminco's Port Pirie Lead Smelter began a modernisation of its lead and precious metals refinery operations. Driven by the anticipated closure of its Broken Hill mine, the new refining process replaced the locally developed continuous process, which had been in operation since the 1950's. Commissioning of the new plant was staged, beginning in late 1997, and finishing early in 1999. The new plant provides for batch refining of lead, and the use of vacuum induction retorting and bottom blown oxygen cupel technology in the silver refining area. The project has resulted in an increase of lead production capacity of 11% and allows the treatment of a wider range of concentrates than was formerly possible. The most significant change has been to double the smelter's silver capacity to over 400 tonnes per annum. This paper describes the successful implementation and optimisation of the new refinery, which is now consistently meeting design capacity.

Jan 1, 2000

By Tom Marttila

During the last few years, when a new tankhouse or a major modernization has been planned, automatic or semiautomatic crane and grab systems have at least been considered. It seems that in the future tankhouse managers for new, modernized and even old tankhouses will be looking for a proven and reliable system for automatically moving and positioning electrode loads in the tankhouse and in storage areas. In this paper, we will describe the Wenmec solution for automatic electrode handling. The advantages of automatic handling and very accurate electrode positioning will be discussed, and the way Wenmec has solved the problems in mechanical construction and in automatic, accurate and reliable positioning will be presented.

Jan 1, 1990

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Jae-Woo Ahn

Waste acids containing phosphoric, acetic, nitric and hydrofluoric acid were produced during the etching process of liquid crystal display and semiconductor manufacture. In recent years, the attention on the treatment of industrial waste acids has been increased considerably according to the reinforcement of the environmental regulations as well as the implementation of the economic considerations about the waste acids. Fundamental studies on the separation and regeneration of the mixed waste acids were conducted using Cyanex 923, Tri-octyle phosphate and 2-Ethylhexyl alcohol as an extractant by solvent extraction. It is considered that the extraction of liquid crystal display waste acids with Cyanex 923 and Tri-octyle phosphate, semiconductor waste acids with 2-Ethylhexylalcohol is applicable for the separation and recovery of acid. Finally, the acceptable recycling process from the multi-component waste etching acids was proposed.

Jan 1, 2006

By Hazoor Singh Sidhu

Materials degradation due to corrosion is the major problem in power generation equipment, gas turbine, fluidized bed combustion, industrial waste incinerators etc. Some super alloys have been developed, but they are unable to have different properties to meet the demand of today?s industry. Therefore, a composite system of a base material providing the necessary mechanical strength with a protective surface layer different in structure and/or chemical composition can be an optimum choice in combining material properties. Thermal spray coating of the components before they put into service by suitable surfacing alloy and with suitable coating method can increase the life of these components several fold. Choice of right coating method and alloy for a particular application is extremely important to get the desired service life. The corrosion of some materials and the role of HVOF thermal spray coatings to counteract the same have been reviewed, with an aim to understand the phenomena along with various applications.

Jan 1, 2006

By L. Trincado

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 ton of copper per year and 5.4 million ton of ore per year. Copper production has steadily been increased to 57,290 ton in 2002. Forecast copper production for 2003 is 60,000 ton for an ore treatment rate of 8.5 million ton. Several improvements in the heap leach process have been implemented. The main process improvements are related to the optimization of heap height, particle size, irrigation rate and leach cycle, in addition to a better heap drainage design and a solution management system. A first dump leach operation was started in 1999 at a production rate of 1,922 ton of copper. A second dump leach operation was started in early 2002 at a production rate of 2,805 ton of copper. Dump leach production will be increased over time to as much as 24,000 ton of copper. The main heap leach process improvements, as compared to the original plant design, as well as the main dump leach operating parameters are discussed in this paper.

Jan 1, 2003

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company - Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide and a very low content of lead oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching followed by electrowinning. Recovery of zinc in the form of zinc powder was over 90%. This powder can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1993

By F. Leclerc, V. Rebeyrolle, M. Revil-Baudard, A. Jardy, M. Založnik, H. Combeau

"Since the quality of Vacuum Arc Remelted ingots is linked to their chemical homogeneity and metallurgical structure, a modeling study of the solidification during VAR has been undertaken. It is based on the solution of the coupled transient heat, momentum and solute transport equations during the remelting of a cylindrical ingot. Solidification mechanisms implemented in the model include a full coupling between energy and solute transport in the mushy zone, and accounting for nucleation and finite diffusion of solutes at the microscopic scale, in both solid and liquid phases. This modeling can be applied to actual multi-component alloys. In this paper, the macrosegregation in Zircaloy 4 ingots is investigated. To validate the model, one single melt of a homogeneous electrode has been specifically performed. The comparison between the predicted macrosegregation and the experimental results shows the importance of accounting for solutal convection to forecast properly the macrosegregation in remelted ingots.IntroductionVacuum Arc Remelting of zirconium alloy ingots is a key step in the manufacturing process of fuel assembly components in nuclear reactors. The control of the chemical homogeneity is indeed fundamental to ensure the quality and the in-reactor performance of the final products. Despite the use of electromagnetic stirring to homogenize the liquid melt composition, chemical heterogeneities develop in the mushy zone during the solidification stage. One of the main challenges for zirconium producers, as well as titanium producers, is to master the VAR process in order to control the macrosegregation in remelted ingots. Macrosegregation results from the association of microsegregation and transport phenomena. The latter are primarily due to the flow in the liquid and mushy parts. It is now well established [1-4] that the hydrodynamics of the melt pool in a VAR ingot depends on the combined action of the followings: thermal and solutal buoyancy, self-induced electromagnetic force and the periodic centrifugal force caused by the angular movement generated by the stirring. However, for zirconium alloy ingots, the effects of thermal and solutal buoyancy forces on macrosegregation through their influence on the flow in the mushy zone have not been clearly identified."

Jan 1, 2012

By V. Bhagavathy

This paper describes a method for the determination of traces of rare earths using energy dispersive x-ray fluorescence spectrometry (EDXRF) after preconcentration of their oxine complexes onto activated carbon. Various parameters that influence adsorptive preconcentration of rare earths onto activated carbon viz. pH, amounts of activated carbon and oxine, time of stirring and aqueous phase volume were systematically studied. A numerical method based on simple least square procedure using fifth order polynomial with 25 consecutive values was developed for smoothing and differentiation of EDXRF data which was previously digitized and averaged. First order derivative EDXRF in conjunction with adsorptive preconcentration on activated carbon enables to determine as low as 10 ppb of each of individual rare earth elements.

Jan 1, 1989

By Varadajan Seshadri

The increase in production of continuous casting machines requires long ladle sequences without interruption. Very often the production schedule has to accommodate a variety of steel grades. In such cases downgrading may be inevitable. Models must be made available to study the alternatives that would make possible mixing of steels in the tundish but minimizing the losses due to downgrading the slabs. Physical modeling was used to evaluate the influence of variables such as internal geometry of the tundish, presence of turbulence inhibitors, depth of ladle long nozzle, weight of steel in the tundish, steel throughput upon the tundish transition curve. Expressions for minimum residence time and transition period have been determined. Mixing-transition is allowed to continue inside the liquid pool in the mold and the final solute distribution in a given cross section is captured by a solidification model. The result is a map of the transition in the final product.

Jan 1, 2006

By Jr. Santafé, Lucas L. da Costa, Felipe P. D. Lopes, Sergio N. Monteiro

"Residual vegetable fibers as leftovers from crops, industrial activities and consumable items are realistic options to be incorporated into low cost polymeric composites with the aim of replacing other commonly used materials. The present work assesses the technical properties of epoxy composites reinforced with residual fibers from the coconut fruit, also known as coir fibers. Based on these properties, an evaluation was carried out on these coir fiber/epoxy matrix composites to be used as building panels and furniture in comparison with conventional materials.IntroductionThe utilization of waste from industrial activities is presently recognized as important way in preventing environmental pollution as well as developing new products. This utilization would also generate employment and contribute to environmental improvement in global scale. Among such wastes, those from lignocellulosic materials represent a considerable potential for practical application. In fact, about 2.5 billion tons of these materials are currently available [1], and their fiber content is an important option for composites fabrication. Actually, lignocellulosic fibers are now replacing synthetic fibers as reinforcement in resin matrix composites owing to specific advantages such as low cost, biodegradability and renewable characteristics [2,3]. Moreover, as abundant waste, some of these lingocellulosic fibers could help reducing the use of traditional materials like wood and plastics in many industrials applications. This would prevent further stress on the environment caused by depletion of dwindling resources associated with forests and petroleum."

Jan 1, 2008

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 G. Roderick Eggert

Material criticality reflects the degree to which a raw material is both necessary and subject to supply-chain risks. This study compares the criticality of selected raw materials from the differing perspectives of the manufacturing sectors of China, the European Union, Japan and the United States.

By Tom McCullough

The purpose of this paper is to discuss the implementation and results derived from installing oxy-fuel burners in a l80 ton copper reverbatory melting furnace. Specific results will be discussed in the areas of melt chemistry, furnace modifications, productivity, process enhancements, and the combustion system capabilities.

Jan 1, 1996

By A. V. Tarasov

A flow-sheet for waste-less processing of spent lead batteries comprises mechanized separation of batteries, smelting of the metallic fraction in a kettle, electrothermal smelting of oxysulfate fraction, refining of crude lead and processing of reverts to produce commercial products. Smelting of lead-containing fraction is performed in an electrothermal furnace using a processing technology developed in the Gintsvetmet Institute and differing from conventional processes by the fact that it does not require any fluxing agent (soda); no matte is formed in the process and the amount of slag produced is minimal, because its formation depends only on the ash content of coke and the quality of battery scrap separation. The process has been patented. It has been introduced on a commercial scale in 1.8 MVA furnaces at the plant of A0 "RyazTsvetmet" (Ryazan, Russia). The process has the following main advantages as compared with conventional shaft-furnace smelting and smelting in a short-drum furnace: the process does not require technical-grade oxygen, the amount of process gas generated is minimized ensuring a decrease in lead-containing dust and sulfur dioxide emissions by 3 to 5 times per unit of lead recovered; a decrease in dust entrainment resulting in lower amounts of recycled dust; lower slag yield (a decrease from 20-25% to 3-5%); lower coke requirement (a decrease from 10-14% to 3-4%). Refining of crude lead is performed using conventional technology but there are several unique features for which know-how is available. Processing of by-products of electrothermal smelting and secondary lead refining (slag, drosses, skimmings) and ebonite fraction (crushed battery casings) is performed in a slag-fuming furnace.

Jan 1, 2002

By Darrin Wikoff

"The data, compiled by the Department of Energy (DOE), indicates that the average industrial plant could reduce its total energy cost by 14.8% by implementing effective Life Cycle Asset Management processes. The actual savings varies by industrial classification, but in all cases the potential is substantial and could have a marked impact on the operating profit of the company.Improvements geared towards improving equipment reliability have distinctive linkages to environmental performance, such as reducing the amount of product and raw material waste through routine monitoring of system parameters through predictive technologies, and preventing interruptions to production cycles with a focus on Overall Equipment Effectiveness (OEE).Alcoa successfully reduced solvent disposal costs by more than 40% and GE reduced greenhouse gas emissions by more than 250,000 metric tons. This presentation will show you how companies have successfully reduced energy and disposal costs through a focused effort on manufacturing process reliability.IntroductionSmelter in the ParkThe quaint town of Portland, Victoria protrudes outward towards Antarctica from Australia’s southeastern coastline. Portland is a quiet rural community surrounded by agriculture that draws tourists by the thousands to the southernmost edge of Victoria by way of breathtaking cliff top views of the majestic Southern Ocean, the intrigue of shipwreck coves along the Great Ocean Road, and what most will call the eighth wonder of the modern world, the “Smelter in the Park”. Integrated within Portland’s beautiful landscape is a 356,000 ton/year aluminum smelter that stands as a symbol of collaboration between nature and industry. Nestled atop a ridge which faces “Sail Rock”, a popular destination of local and visiting fisherman, the smelter is engulfed in a mix of brush and wetland preserves that are home to many of Australia’s feathered and fourlegged natives. Also within its interior you’ll find parks and natural landscapes abundant where man and machines coexist with the native inhabitants."

Jan 1, 2009

By Alicia Esther Ares, Alex Iván Kociubczyk, Verónica Liliana Scheiber, Roberto Rozicki

In the present research the horizontal solidification of Sn-Zn eutectic alloys (Sn-8.9wt.%Zn) is performed, with two opposite senses of heat extraction. From the process of solidification, the thermal parameters (local solidification time, cooling rates and interphases velocities) and grain sizes from macrostructures obtained were determined. The presence of defects in the solidified samples was analyzed, observing that they occur largely in the collision zones of solidification fronts advancing in opposite directions in the samples.

Jan 1, 2016

By Jeffrey L. Zelms

Environmental issues and how they are addressed -- or not addressed -- by the lead industry in the 1990s will determine the eventual fate of lead mining in both the U.S. and worldwide. Clearly, governmental regulation throughout the West will become harsher. Equally clearly, the industry has? failed to educate the public regarding lead. Instead of public support for a critical mineral, we face widespread public ignorance and paranoia. If we can demonstrate the public interest benefits of the industry, the 1990s will be a decade of continuing growth -- not dynamic growth, certainly, but growth at least comparable to the world economy. If, however, we fail to demonstrate the industry's public interest benefits, the 1990s could mark the beginning of the end of our business.

Jan 1, 1990

By Juan B. Cabezas

"The favorable characteristics and workability of plastics as a replacement of wood, lead, stainless steel, asphalt and other materials are described. Various types of plastic have proven to be the most favorable choice for handling a variety of acidic, alkaline and organic solutions, as well as pulps, chemical wastes, slurries or tailings for impoundments. The material origin of various plastics, methods of manufacturing and specifications applied to leaching solutions are discussed, including availability and costs. Examples of select plastics are considered for use as alternatives of other materials under severe environmental requirements.IntroductionHydrometallurgical processes applied to gold recovery, as well as other metals, require the use of strong solutions of alkaline, acidic or organic nature, and may also include a variety of materials with extraneous characteristics and complications for handling in storage.The technology of leaching has been in use for more than 100 years, but the applications of leaching processes in metallurgy have become more commonly used in the last 15 years. Suitable materials for the construction of containers, launders, piping, and various accessories, to be used in the handling of leach solutions or slurries, have become a serious problem. Various metals such as brass, lead, stainless steel, etc., and non metallics including wood, clays, glass, rubber, ooncrete, tars or miscellaneous compounds have been tried in the past with serious limitations in workability and resistance to wear and corrosion. For example, the use of metallic, wooden or glass piping systems would require extraordinary shop maintenance to keep such systems in operation"

Jan 1, 1997

By John J. Friel

Digital imaging systems are particularly useful in microscopy, because they make it possible to extract information not readily accessible by manual methods and to display that information clearly. Computer-aided imaging systems analyze, process and compare images, and of these, image analysis is most useful in materials science. Image analysis quantifies the microstructure by making measurements on the entire field or by measuring the size and shape of features individually. Even true surface area can be calculated. Modem image analyzers make thousands of measurements in seconds, leaving the investigator to interpret the data and relate them to process and material properties. Image processing, which may be necessary to prepare an image for analysis, includes everything from simple contrast transforms and kernel filters to complicated processes such as grain boundary reconstruction using artificial intelligence. An example of image comparison is point-by-point screening of X-ray maps of different elements to extract phases. In all of these operations, the computer makes a large number of measurements in seconds and returns information that could not be realistically obtained by manual methods.

Jan 1, 1992