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By G. Springer

The identification of lost mineral values in mill tailings frequently requires the inspection of hundreds of thousands to millions of particles. The search of these particles can be made automatic by using an electron microprobe. A standard instrument (Cambridge Mark V) was modified by the addition of stepping motors to advance the specimen stage in a controlled manner. The X-ray Signal is monitored continuously by a computer interfaced to the instrument with an analog-to-digital converter. 400,000 particles of a tailings sample can be scanned in about 3 hours. Particles as small as 2 um and containing as little as 3% of a particular element can be detected.

Jan 1, 1982

By Keith Cramer

As a leader in the development of metal extraction technology, Avecia continues to pioneer advancements for the processing of copper through leach, solvent extraction, and electrowinning of copper. From the initial patent of the second generation of oxime 5- nonylsalicylaldoxime in the 1970's; to the effective use of modifier technology; and development of computer assisted modeling programs, Avecia is driving SX technology to maximize extraction productivity. Keys to consider when advancing productivity are: 1) high quality, high performance products; 2) a responsive, partnering approach to technical service; and 3) tools to aid in the education of industry wide technical personnel with a view on continuous improvement. The focus of this paper is on the advancement of tools to aid in the education for optimization of processing copper through solvent extraction. One such tool is Avecia's own customized solvent extraction modeling program called MEUM. MEUM is currently used world wide to analyze plant operations, test ideas for improving operations, assist engineering companies in design, and to teach basic solvent extraction concepts. Recently MEUM has also been incorporated into a University setting. In the spring of 2000 Avecia worked with the University of Melbourne to integrate MEUM into their Mass Transport tutorial class. Students completed exercises to evaluate how operational changes affected a solvent extraction plant's performance. This paper introduces the basic functions of the program and discusses the successful implementation of MEUM into the University of Melbourne curriculum.

Jan 1, 2002

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 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 Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Kurt Westerlund

Cooling of hot sticky gases with solids in a circulating fluidized bed called FLUXFLOW is described. Fluxflow is used for gas streams from metallurgical reactors, e.g., Isasmelt copper in Australia and TBRC for lead in Sweden. The features and potential of this technology in metallurgy and waste treatment ie described. The FluxfLow la a new, cost efficient high availability solution to treat hot sticky gases that has made new gas handling and heat recovery flow sheets available to the process industry.

Jan 1, 1994

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 Jong-Shin Chang

The Onsan smelter has tried to do various activities to decrease operation costs. With several expansion projects, the Onsan smelter has aimed at not only a quantitative growth but also qualitative growth through efforts improving operations equipment and processes. Activities to reduce operation costs have been one of those efforts. In particular, the energy cost of operation has been a main target for reduction. The activities to save energy have been carried out in two ways. One is to recover and utilize waste heat as much as possible and another is to replace existing equipment and processes with more energy-efficient ones. This paper reviews recent improvements and future plans for energy saving activities at the Onsan smelter.

Jan 1, 2006

By Takahiko Okura

Sulphur, with its multiple oxidation states, play critical roles in many processes, ranging from regulating enzymes in plants, to acidifying aquatic systems, and to affecting the global climate. Most of non-ferrous smelters have been contributing to reduce atmospheric emissions of sulfur dioxide to acceptable levels, converting it to sulphuric acid and/or gypsum. However, some amount of SO2 gas is still emitted from isolated smelters. Furthermore, sulphuric acid is competing with involuntary elemental sulphur in the market. This situation puts the non-ferrous metallurgical industries to develop a new sulphur fixation process. This paper briefly describes the new technologies for fixation, followed by the novel proposal to convert SO2 gas to elemental sulphur using organic materials. Finally, the feasibility will be presented technologically and economically.

Jan 1, 2006

By S. Suda

Hydrogen storage materials have been investigated for more than 30 years, particularly on metal hydrides. These materials are, however, considered today impractical because of their poor hydrogen capacity measured by mass density and their poor surface properties and characteristics against impurities. Recent R&D activities have been located in new categories of materials such as complex hydrides and chemical hydrides. Among these materials, NaAlH4 (one of alanates), Li-based complex hydride, and NaBH4 (SBH: sodium borohydride) are 3 major candidates as hydrogen storage materials. In the presentation, SBH as a non-reversible on-site but recyclable off-site is described in view of its practical availability as the source of H- (protide) applied for a new type of fuel cell named Direct Borohydride Fuel Cell (DBFC) and H2 (hydrogen) for Proton Exchange Membrane Fuel Cell (PEMFC).

Jan 1, 2006

By Henry Salomon-De-Friedberg

Quebrada Blanca has had to overcome numerous challenges in achieving design throughput. The paper reviews how actual practice has evolved from the original design. The major challenges that were encountered from heap leaching to solvent extraction, the tankfarm and through to electro winning are discussed. The eventual solutions to some of the key issues are presented.

Jan 1, 1999

By Matti Hämäläinen

Outokumpu has developed a new chloride leaching process, HydroCopper?, for copper concentrates. The process utilizes the cupric ion as oxidant, which is able to dissolve chalcopyrite. After solution purification monovalent copper is precipitated as cuprous oxide, Cu2O, using sodium hydroxide. Copper product is produced from Cu2O by reduction, melting and casting. An essential part of the new process is chlor-alkali electrolysis, which regenerates the reagents used. All impurity metals are removed before Cu2O precipitation, because otherwise they would report to the copper product, impairing its quality. A multistage solution purification scheme has been developed consisting of firstly, chemical precipitation of impurity metals by pH increase, secondly, cementation of silver and thirdly, removal of trace multivalent ions using ion exchange. This paper describes the characteristics of solution purification in the HydroCopper? process based on the laboratory tests and pilot runs made by Outokumpu Research Oy.

Jan 1, 2003

By L. Dornelles, M. H. Prediger, R. de C. de S. Schneider, D. A. R. Lopez

In this work it was evaluated the environmental impact of sunflower plantation for biodiesel production. It was considered, for life cycle analysis (LCA) of sunflower in familiar agriculture in the South of Brazil, data collected in 23 experimental farmings with sowing in the period from August to November (2006 -2007). The LCA has considered the plantation conditions, energetic efficiency, man power, diesel volume, type of machines, fertilizers and pesticides used. From the analysis carried through it was evidenced that the sunflower produced in small scale does not need the use of tractors to have an excellent productivity and low impact. Therefore, the sunflower can be cultivated, with the necessary cares, in periods that do not compromise the man power for other cultures and the sunflower is an alternative so that the familiar property can produce biodiesel.

Jan 1, 2008

By R. M. Luna-Sánchez

Electrochemical studies, particularly Evans? diagrams, have been employed in hydrometallurgy to simulate and explain the redox phenomena that take place at mineral and metal surfaces during operations such as leaching and cementation. However, despite their utility, in some cases, the combination of the cathodic and anodic branches, determined separately, does not reproduce the chemical environment present when both processes occur simultaneously on a specific surface. In the present paper, limitations of Evans? diagrams are analyzed through two examples: silver sulfide cyanidation and gold cementation on zinc. In both cases, the surface kinetics are sensitive to the local pH and cyanide levels. When the electrochemical oxidation of silver sulfide or the reduction of gold are performed in the absence of its corresponding redox reaction, the local pH obtained does not simulate the real situation and the combined reaction kinetics may be very different from those determined from the Evans? diagrams.

Jan 1, 2003

By Ahmet Geveci

In this work it is aimed to assess the plant analytical data which appeared during efforts to decrease the effect of carry-over slag (basic oxygen furnace slag) that can not be prevented to leak during tapping of steel in the ladles. While the amount changes, carry-over slag that escaped to ladle, consists of appreciable amount of reducible oxides (?FetO? and MnO) which act as oxygen source for steel bath. By using aluminum dross, containing %30-35 metallic aluminum, which is a non-recoverable process outcome (discard) for most of the aluminum factories, slag reduction behavior will be analyzed together with other parameters such as reaction time, initial amount of total Fe+MnO, amount of reducing agent and reducing effect of soluble aluminum in steel bath while obtaining a slag composition which promotes higher desulphurization capacity and inclusion removal for liquid steel.

Jan 1, 2006

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 Miguel Olivas-Martínez

A two-dimensional computational model for the hot filament chemical vapor deposition (HFCVD) process to produce diamond films is presented. The model incorporates the transport of momentum, energy, and mass inside the reaction chamber of a HFCVD reactor. The gas-phase homogeneous reactions were represented by a simplified reaction mechanism. The gas-phase transport equations were coupled to the kinetic expressions representing the catalytic dissociation of the molecular hydrogen at the filament surface and the deposition rate of the diamond film on the substrate. The computational model was solved numerically by means of a commercial software. The model predictions showed good agreement with the experimental data reported in the literature in terms of both temperature and methyl concentration profiles along the filament-substrate center distance. Examples of the potential applications of the present formulation for the design and further optimization of the HFCVD reactor are discussed.

Jan 1, 2006

By Hiroyuki Sano

Elimination of heavy metals from the incineration fly ash by the chlorination volatilization method had been already developed and the effectiveness of this method was confirmed by the present authors. In this study, this method was applied to the elimination of heavy metals, mainly lead, from the incineration bottom ash. Since the fly ash contains a large amount of chloride, heavy metals in the fly ash are easily chlorinated. On the other hand, the addition of the chlorination agent is a key point for applying this method to the bottom ash, because it hardly contains chloride. The effects of various variables such as a kind of chlorination agent, adding quantity of it and temperature on the elimination ratio were investigated and the harmlessness of the residual ash was evaluated. The preferable condition was proposed from the recyclability of the bottom ash.

Jan 1, 2006

By Thomas Frost

In this time of market globalization, many industrial companies are including detailed arbitration clauses in their international contracts, in order to avoid the potential costs, delays, and uncertainties of litigation in foreign courts. Arbitration is less expensive and more flexible, procedurally, than court proceedings, and arbitral awards enjoy much greater international recognition than judgments of national courts. More than 134 countries have signed the 1958 United Nations Convention on the Recognition and Enforcement of Foreign Arbitral Awards, known as the "New York Convention", which facilitates the enforcement of arbitral awards internationally. There are several other similar arbitration conventions that provide for the enforcement of cross-border arbitral awards. Additionally, arbitral awards are not subject to appeal, whereas judgments of national courts are routinely subjected to a lengthy appeals process, and there are very few viable bases to challenge arbitral awards. This discussion will review key considerations in drafting arbitration clauses, including choice of law and choice of forum considerations; issues surrounding the selection of arbitrators; the discovery process; presentation of evidence; and enforcement of arbitral awards.

Jan 1, 2006

By B. Fresz

Before aluminum is utilized in automotive bodies, the longevity of the electrodes employed in the resistance spot welding of aluminum must increase. This paper explores the affects of electrode composition on electrode life. To compare these variables, electrode tests were completed on a Taylor Wield welding machine using, Cu-Cr, Cu- Zr, Cu-Cr-Zr, Cu-Be, and Glidcop electrodes tested to 12.5%, 25%, 50%, 100%, and 150% lifetimes. Electrode diameters were found via a magnification technique using a PULNIM video camera attached to a low magnification Wild Heerbrugg stereo-zoom microscope. From these measurements, graphs of electrode life verses face diameter and weld number verses face diameter were created. Analyses of these graphs suggest that a single failure mechanism is responsible for electrode failure, though the number of welds until failure (100% electrode life) varied with composition (700-2000 welds).

Jan 1, 1999