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By E. J. Peuraniemi

Recently commissioned Kennecott-Outokumpu flash converting was developed to replace the approved but environmentally outdated Peirce-Smith -converting to satisfy the globally tightening emission regulations. In the present study, dust formation and reaction mechanisms of two copper mattes with different experimental parameters were studied in lean suspension conditions. Both mattes had very high copper content of approximately 75 wt% and low iron content of 4.5 wt% and 1.2 wt% Fe. A laboratory scale, vertical laminar-flow furnace with a low feeding rate was used to simulate the phenomena taking place in the reaction shaft of a flash converter. Experimental conditions included temperature of 1300 °C with reaction gas oxygen contents of 20 vol%, 50 vol%, and 75 vol%. In the experiments, sieved particle fractions were fed to the furnace and sampled after short reaction time intervals by quenching them into a water film. Collected particles were analysed chemically for their main elements to define their removal rates. Also, optical and scanning electron microscopy with EDS-analyser were applied to determine phenomena occurring during reactions. Kinetics of oxidation as well as ignition of particles are discussed. Changes in particle morphology, size, and composition are reviewed to describe dust formation and reaction mechanisms.

Jan 1, 1999

By C. D. Seybert, J. W. Evans

"The elimination of convection is essential in experimental investigations of diffusive transport (of heat and matter) during solidification. This paper describes an investigation of an approach whereby a magnetic field gradient is applied to a electrically non-conducting diamagnetic liquid. A magnetic body force then arises which is dependent on the volume susceptibility of the liquid and thereby on the density. With the field gradient aligned vertically and of correct magnitude, the variation of gravitational body forces due to density variations (arising from temperature variations, for example) can be counterbalanced by a variation in magnetic body force.Preparatory to a study of convection control in diamagnetic liquids, PN measurements have been made of the convection occurring during the solidification of water. A peculiar flow arises because of the density maximum at 4°C. Modeling of the flow the steady-state solidification of water in an extremely high field magnet at the NHMFL indicates that flow can be significantly reduced, but it is suggested that, due to field gradient variations within the cell, flow cannot be completely halted. INTRODUCTIONNatural convection is inherently a part of terrestrial solidification. Density-based convection during solidification, due to gradients of temperature and/or concentration, has a significant effect on a material's properties. The design of products with specific material characteristics has required the development of many processes to control convection (such as in the growth of semiconductor crystals, and electromagnetic stirring in steel casting). The expansion of fundamental knowledge about the process of solidification requires collecting data in the absence of density-based convection, while most of science's solidification data (and thus the equations that science has fitted to those data) have been obtained under the influence of gravity. Only relatively recently, through clever experimental design (e.g., drop towers, high altitude parabolic flights, and space laboratories), have investigators been able to study solidification in an environment with ""micro-gravity""."

Jan 1, 2001

By Clodualdo C. Conde

In order for Philippines Associated Smelting and Refining Corporation (PASAR) Corporation to remain a leader in the copper smelting and refining industry, continuous improvements in plant technology are required. Reliable performance of plant equipment is essential for a competitive smelting operation. PASAR is constantly searching for the best equipment and technology to allow us to manufacture products more efficiently. When the Smelter was commissioned in 1993, the Flash Furnace off-gas treatment system was a constant source of problems. There were frequent shut-downs of the electrostatic precipitator due to material buildups on the discharge electrodes and collecting plates. In 1998, the precipitator was successfully upgraded to eliminate the buildup problems and to increase the collection efficiency. The upgrade greatly reduced down time and maintenance, and the enhanced collection efficiency also eliminated pluggage problems and material losses in the Acid Plant. This extensive precipitator upgrade was accomplished during a 30-day Smelter turnaround.

Jan 1, 1999

By S. F. Cheng

Among the many extraordinary features of the rare earths are their magnetic and magnetoelastic properties. The rare earths, e.g. Tb, Dy, Nd, Sm, are known worldwide for their large magnetocrystalline anisotropy and magnetization, which has led to the importance of magnetic rare earths as vital ingredients of modem permanent magnets. In this paper, we focus on the strain dependence of these giant effects which gives rise to huge magnetostrictions, magnetomechanical couplings, and ?E effects. Magnetostrictions greater than 10-3 have been measured at temperatures as high as 500 K. At low temperatures magnetostrictions reaches -1%. ?E effects - 10. No other solid state material has matched these values. A proper balance of magnetic anisotropy and magnetostriction, plus a proper choice of crystal axes lead to alloys which can switch large quantities of energy between the internal (magnetic) and external (mechanical) states with the application of small triggering magnetic fields. In addition to the traditional use of these materials in transduction, they are particularly valuable for smart systems where reliability and robustness are needed such as active structure stiffening and active vibration control.

Jan 1, 1997

By Leonard J. Friedman

The contact process for the production of sulfuric acid has been used commercially since before the turn of the century (1880?s), and rapidly replaced the chamber process after the development of vanadium catalysts in the early 1900's (1910's - 1920's). Plant size has increased from a few tons per week to single train units in excess of 4,000 tons per day. Much of the history of the contact process is in the minds of the few remaining early process pioneers that started in the industry in the 1920's and 1930?s, and in sulfuric acid industry books published in 1921, 1925, 1936, and the last Deucker and West in 1959. Since those not familiar with history are doomed to repeat the failures and mistakes of the past, this paper includes a brief history of the contact process along with the history and development of equipment and materials in each equipment area of the process. The main focus of the paper is to present the development and analysis of equipment and materials in the contact section of the sulfuric acid plant - from the dry tower to stack.

Jan 1, 1999

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 J. A. S. Tenorio, A. B. Botelho Junior, I. A. Anes, D. C. R. Espinosa, M. A. Caralho

Recovery of metals from reserves with low grade and from waste with high presence of contamination is a challenge to be overcome. Metals like nickel, cobalt and copper could be recovery from nickel laterite leach waste by many different processes. Among recovery processes that could be applied are ion exchange, solvent extraction and precipitation. The aim of this work was recover copper from liquor of nickel laterite by precipitation using chemical reduction. Copper concentration in liquor was 146 mg L −1 and reducing agent used was sodium dithionite 1 mol L −1. Influence of stirring speed was studied between 0–200 rpm. Results indicated a selective precipitation of copper on solution with others metals at 240 mV. The analyzes were conducted in SEM, energy-dispersive X-ray spectroscopy and XRD, that indicated presence of copper and sulfur.

Mar 1, 2018

By Dachun Liu, Wenlong Jiang, Baoqiang Xu, Yongnian Dai, Bin Yang

"In the traditional method for refining of indium, glycerin-KI and glycerin-NH4Cl are used as electrolytes to remove Cd and Tl by electrolytic refining, which produces In with a purity of 99.995%. Large quantities of polluted industrial waste water are the result. It is calculated that the saturated vapor pressure of Cd and Tl are between 1-200 Pa, which is much larger than the vapor pressure of In. Thus, the study of removing Cd and Tl was carried out over the temperature range between 700-950 °C and pressures between 1-15 Pa. After vacuum distillation the contents of Cd and Tl in crude indium could sharply fall below 1 ppm..IntroductionIndium is a is a pale blue and silver white metal, and has high ductility [1-2]. Pure indium is generally used as a raw material to produce semiconductor compounds, fluorescent material and ITO targets [3]. Sublimation, zone melting and electrolytic refining are major methods to produce pure indium from crude indium. Electrolytic refining is the main method to product pure indium at present. High productive efficiency, simplicity of operation and short cycle of production are major advantages. However, glycerin-KI and glycerin-NH4Cl are used to remove Cd and Tl in electrolysis method. Large quantities of polluted industrial waste water are the result[4]."

Jan 1, 2012

By Michael J. Virnig

The formation of crud is a normal part of operating a solvent extraction circuit for the recovery of copper. It periodically must be removed from the circuit. This results in significant costs in terms of manpower, downtime, and loss of circuit organic. Field studies have been carried out that show that the presence of a thermodynamic modifier in the organic phase contributes to crud formation. In an effort to better understand what factors contribute to crud formation, laboratory studies involving competitive adsorption studies with model solids have been carried out. The results of these laboratory studies will be integrated with the results of the field studies to present a better understanding of crud formation.

Jan 1, 1999

By D. Ducharme, J. Lenz

Operation of the Kidd electrolytic zinc plant commenced in 1972 with a cellhouse capacity of 105,000 tonnes of zinc cathode. The original cellhouse layout consisted of 42 parallel rows for a total of 588 cells. As leaching capacity increased, the cellhouse was expanded to 630 cells. Zinc cathode was manually stripped from plant start-up until the development of a mobile automated stripping system in 1994. Machine development continued until a second unit was placed in production in 1996, from which point, 60 % of the cellhouse was being stripped with the automated system. The final phase of the project was implemented in 1999 with the commissioning of two more automated strippers. This paper describes the implementation of the automated stripping system and its impact on cellhouse productivity.

Jan 1, 2000

By Paulo von Krüger

This paper deals with the cell design and operation of a tin electrorefining 1:5 pilot plant. The purpose of the work was the fitting of the basic parameters to be used in a full-scale tankhouse from a major Brazilian tin producer. The main specific difference was the use of permanent stainless steel cathodes instead of conventional tin starting sheets. The results of both product quality and operating parameters are discussed.

Jan 1, 2003

By June-Yong Eom, Jong-Jin Pak, Jung-Mock Jang, Min-Kyu Paek

The nitrogen solubility in liquid Mn-Si, Mn-Si-Fe, Mn-Si-C and Mn-Si-Fe-C alloys has been measured by the gas-liquid metal equilibration technique in the temperature range of 1673-1773 K. The additions of silicon, iron and carbon significantly decreased the nitrogen solubility in liquid manganese alloys. The experimental results were thermodynamically analyzed by the Wagner’s formalism to determine the first- and second-order interaction parameters of silicon, iron and carbon on nitrogen in liquid manganese. The thermodynamic parameters can be used to predict the nitrogen solubility in ferromanganese and silicomanganese alloy melts as functions of the melt composition and temperature at given nitrogen partial pressures.

Jan 1, 2014

By Donald O. Voit

A BASIC language program has been written that simulates the performance of an integrated solvent extraction circuit consisting of an extractor, a reflux fed scrubber, and a stripper. The program is designed to simulate the performance of a circuit having an aqueous feed containing each of the lanthanides as well as yttrium. The Kremser equation is used to determine the separation occuring in each section of the circuit. The required input variables are the feed composition, the separation factors, the light key extraction factors and extractor feed zone distribution coefficient, the number of stages, and the reflux ratios. The program calculates the composition of the streams at each node in the circuit, the total loading, and the remaining distribution coefficients. User interaction with the program is essential. The program has no capability to determine if the calculated values are consistent with various real restraints. Knowledge of the physical, chemical, and equilibrium behavior is essential to successfully utilize the program. The number of iterations required to achieve steady-state provides insight to the circuit response times. With suitable supervision the program can be used as a simulator for operator training.

Jan 1, 1989

By Abhishek Asthana

The incineration of Municipal Solid Wastes (MSW) is an attractive process for reducing the volume of the wastes and recovering their energetic value, which, however, requires to be strictly controlled in order to limit its impact on the environment. In this context, we have undertaken the mathematical modeling of the different sections of a typical incineration plant. The combustion of the waste bed, usually carried out on a moving grate, is at the core of the process. This paper presents the 2-dimensional, steady-state model that we have developed for simulating the MSW combustion. The model describes gas flow through the porous waste particle bed, the gas-solid reactions, conductive and radiative heat transfers, drying of the feed, its pyrolysis and the emission of volatile species, combustion of the pyrolysis gases, the formation of char and its gasification by water vapor and carbon dioxide, and the consequent reduction of the bed volume. Pyrolysis kinetics distinguish between cellulosic and non-cellulosic materials and are experimentally derived from our laboratory measurements. The calculated results give a deep insight into the various involved phenomena, an example being the complete consumption of oxygen in a large zone of the bed and the related appearance of a char gasification zone. The influence of various operating parameters, like the temperature and flow rate of primary air, is presented and explained. Finally, the effect of stirring the waste bed on the moving grate is also analyzed.

Jan 1, 2006

By Heinz Böni, Christian Ludwig, Bernhard Steubing, Uca Silva

"Chile will soon have to find solutions for dealing with rapidly growing quantities of Waste Electrical and Electronic Equipment (WEEE) due to its strong economy and fast increase of internet and communications technology usage. To support this process, the state of the Chilean recycling infrastructure as well as government, industry and consumer efforts to deal with ewaste were analyzed. Current e-waste quantities were assessed and future flows were predicted using a material flow analysis model. In this model computer hardware was used as tracer equipment for WEEE. Best available numbers indicate that today’s formal recycling infrastructure receives less than 3% of the annual quantities of computer waste. This study represents the most comprehensive analysis regarding e-waste in Chile, identifying relevant streams of e-waste and providing a basis for authorities and producers of electronic goods in order to take the necessary actions to establish an adequate recycling system.IntroductionSince 1991, Chile has experienced a period of strong economic growth. It is amongst the countries with the fastest development in the sector of Information and Communication Technologies (ICT) in Latin America and the number of people with access to ICT has been growing rapidly. The high growth rates of the computer market over the last years are representative for the ICT sector with the consequence that the generated quantities of electronic waste are increasing rapidly [1, 2].Waste Electrical and Electronic Equipment (WEEE) or e-waste is “any appliance using an electric power supply that has reached its end-of-life” as defined by the OECD [3]. Even though the overall waste management in Chile has improved much over the last decade, the issue of ewaste was hardly addressed. Due to the value of the materials contained in computer waste - such as precious metals, basic metals as copper or plastics - it may be assumed that an important quantity is already being recovered. This usually takes place on the informal market under questionable conditions for human health and the environment [1, 2, 4]."

Jan 1, 2008

By G. P. Swayn

Recycling of dusts produced in a flash furnace by direct injection provides the opportunity to reduce recycle loads to the reaction shaft, lower fuel requirements and possibly increase metal recovery to products. Ausmelt has provided an Ausmelt lance system for injecting dusts collected from the waste heat boiler and electrostatic precipitator units, directly into the slag melt. This has been installed and operated in the Kalgoorlie Nickel Smelter with systems for feeding dust, for firing with oil and air, and for raising and lowering the lance. Modelling and testwork development of dust injection, results of commercial trials and design considerations for further opportunities of the Ausmelt lance system, are discussed.

Jan 1, 1994

By Matthew Jeffrey

Leaching, cementation, electroplating and flotation are all electrochemical phenomenon. They are also key processes in the hydrometallurgical treatment of metals. Unfortunately electrochemical methods tend to be under-utilized when studying these processes and one possible reason for this is the confusion surrounding the large number of electrochemical techniques available. In this paper four former PhD students of Professor Ian Ritchie present an insight into how one electrochemical technique can be used to compliment rate/kinetic studies. The paper details how to perform the experiments, interpret data, and recognize complications with the results. Examples where this approach has been highly successful are presented, and include: cementation of zinc by aluminium, cementation of copper by nickel, cyanide leaching of gold and the cementation of gold thiourea by mild steel. The examples illustrate that this universal approach adopted by Ian Ritchie provides the key to understanding the mechanism of many hydrometallurgical reactions.

Jan 1, 2003

By Akihide Nagao

The behavior of impurity hydrogen that is contained in starting material or picked up during processing has been little investigated up to now. The hydrogen microprint technique is applied to determine the microscopic location of impurity hydrogen during deformation in aluminum without hydrogen charging. Three kinds of pure aluminum of 99.99% are prepared, in which hydrogen content is varied by changing the atmosphere when they are melted and heat-treated. After rolling, tensile specimens with a gage size of 4 x 4 rnm and 0.5 mm in thickness are stamped out from these three kinds of aluminum sheets. These specimens are covered with a liquid nuclear emulsion of silver bromide crystals, stretched by 5,10 and 15 percent plastic strain or fractured, developed and fixed. SEM micrographs reveal a number of silver particles on the slip lines and on the grain boundaries. Also shown is that the more hydrogen present in the specimen, the more silver grains appear on the slip limes and on the grain boundaries. Consequently, it is concluded that impurity hydrogen is transported to the surface with gliding dislocations during deformation.

Jan 1, 1998

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003

By Shunhong Huang

To improve understanding the effect of heavy metal chromium on soil biota, laboratory incubation experiment was carried out in the soils contaminated artificially with five concentrations of chromate (50, 250, 500, 1000 and 2000 mg kg_1 soil) over time (35 days). The population and diversity of bacteria, fungi and actinomycetes in soils were measured as indicators of soil microbial processes in the disturbances mentioned above. Incubation experiment results elucidated that the population and diversity of microorganisms decreased with increasing Cr (VI) concentration. Furthermore, various microorganisms showed different sensitivity to total Cr contamination. The sensitivity of microbial population to chromium contamination was in the order: actinomycetes >bacteria>fungi. The resulted implied that the microorganism can be used as an indicator of chromium contamination.

Jan 1, 2008