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By Vahid Tajdar

The behavior similarity between pile and cone penetration test, has guided the researchers to use the CPT results in prediction of piles bearing capacity. In this article, artificial neural networks have been used to study about relation between cone tip and sleeve friction strength obtained from cone penetration test and ultimate pile bearing capacity, obtained from static pile load test. Artificial neural networks "ANNS" is a form of artificial intelligence. ANN tries to dramatize the human nerves & brain system biology structure in self-structure. In this article, the results of relevant studies about the prediction of ultimate pile bearing capacity in especial area of soils are presented by use of back - propagation neural networks. The results of static pile load test up to failure on 63 piles with closed end and CPT test results in the place of construction these piles use in order to confirm and creation ANN model. Comparing predicted ultimate pile bearing capacity by utilizing ANN with the numbers which are predicted by 5 common traditional methods shows that using of artificial neural networks is a suitable method for predicted ultimate pile bearing capacity in identified area of texture of soil moreover it has a better operation in comparison with common traditional methods.

Jan 1, 2006

By Derek Fray

Molten salts have been used for the extraction of metals since the 19th century but, recently, many interesting processes have been investigated using mixtures of molten salts and different cathodic materials. In several existing processes, the cation is simply discharged from melt but, in some cases, complications arise when the electrode potentials of the cations are relatively close. For example, the co-deposition of sodium with aluminium in the Hall-Heroult process is discussed in terms of electrode potentials of the components in the molten electrolyte. Similar considerations will also be given to the anodic reactions with respect to chlorine, oxygen, carbon dioxide or monoxide evolution from chloride-oxide melts. In some cases, the cathodic product interacts with the cathode to produce new and exciting products such as nanotubes from carbon or titanates and reduced titanium oxides from titanium dioxide. Depending on the electrode potentials, it is also possible to completely change the cathodic reaction from discharge of the cation in the salt to ionisation of the anions in the cathode. Examples are given of the reduction of metal oxides to produce metals, high technology alloys and nanomaterials and the cathodic refining of liquid metals.

Jan 1, 2006

By H. Y. Cho

LS-Nikko Copper Inc, has been operating its Onsan copper smelter since 1979. The smelter began its operation with a designed capacity of 80,000 tpa of copper from concentrates and its smelting capacity was increased to 140,000 tpa of copper by modifying the existing line in 1988. The Mitsubishi Continuous Smelting and Converting Process has been operating since 1998 at the initial capacity of 160,000 tpa of copper. In 2002, the smelting capacity of the Onsan smelter has been increased to 426,000 tpa of copper from concentrate. Now the Onsan smelter has plans to increase its smelting capacity to 500,000 tpa of copper from concentrates by 2010. During the expansion work, the modernization of facilities will be accompanied by an increase in smelting capacity, via the Outokumpu process. This paper reviews the brief history of smelting capacity increase in Onsan smelter and its Outokumpu process modernization plans.

Jan 1, 2006

By Wang Yun-yan

In order to examine the adaptability and the kinetics of leaching different gold ores in alkaline thiourea system, six kinds of gold concentrate and/or calcine with different physical and chemical properties were chosen as objects. The leaching behaviors in alkaline thiourea system with high stability, acidic thiourea system and alkaline cyanide system were compared. Changes of phase, surface appearance, particle distribution and specific surface area of six kinds of gold ores before and after leaching were studied in virtue of modern analytic techniques, e.g., XRD, SEM, and so on. The results indicate that alkaline thiourea solution can be used to leach gold ore, for oxidized gold concentrate removed arsenic by microbe pretreatment(4#) the leaching rate of gold is up to 82.68%, such conclusion overthrows the parlance reported that pH value must be less than 1.78, or gold can not dissolve in thiourea solution. Chemical components and phase are related to gold leaching rate, different gold ores are fit for different leaching system, and alkaline thiourea solution is suitable for the pretreated oxidized gold ores with low content of sulfur and in which the main phase was SiO2, phase almost does not change after leaching basically. Generally speaking, when leaching in alkaline thiourea solution, surfaces of gold ores with glaze change greatly to ones with coarseness, distinct trace and holes of corrosion. Particle size decrease and specific surface area increase of gold ores after leaching in alkaline thiourea solution with high stability except gold concentrate of Zhongyuan gold smelter(5#).

Jan 1, 2006

By Manuel Pérez-Tello

An experimental study on the oxidation of chalcopyrite (CuFeS2), pyrite (FeS2), covellite (CuS) and chalcocite (Cu2S) particles was conducted by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Oxygen concentration in the process gas was set to 40 and 70% by vol. and a heating rate of 40 °C/min was used. Response variables included: the temperature of incipient reaction, the total exothermic heat of reaction, particle mass, morphology, and mineralogy of the reacted particles. Based on the experimental data and phase stability calculations, reaction mechanisms were proposed to represent the behavior of the particles during oxidation. The reaction mechanisms were verified by X-ray diffraction (XRD) analyses of the oxidized particles, and by thermochemical and mass balance calculations to reproduce the DSC and TGA thermograms. Overall kinetic models were developed to represent the evolution of the exothermic heat of reaction for each mineral as a function of time. Experiments conducted with copper concentrate particles containing the minerals studied suggest that the reaction mechanisms for the individual minerals can be used to represent the oxidation behavior of the copper concentrate particles.

Jan 1, 2006

By J G. Petrie, H von Blottnitz

The selection and design of process options to deliver outcomes consistent with sustainable development requires simultaneous consideration of multiple objectives, within a climate of uncertainty û including the environmental and social aspects of technology management in addition to the technical and economic aspects of such. An issue of particular relevance in primary metal production is the deportment of minor and trace components within orebodies, products and wastes and the implications of such deportment for eco-efficiency û in particular, the long-term environmental impact of solid waste management practices. The identification of opportunities to enhance recovery of valuable by-products and simultaneously improve the environmental acceptability of final waste output requires a clear understanding of the distribution of the relevant ore components, which results from the choice of processing route and unit operation efficiency. This is challenging, given that process streams generated during primary metal production are generally poorly characterised and the behaviour and deportment of trace to minor and trace components is not well understood. This paper demonstrates how current data gaps and inconsistencies can be systematically addressed through the meaningful reconciliation of empirical plant data with a fundamental understanding of the mechanisms and parameters influencing element behaviour and deportment during the formation and subsequent beneficiation of mineral ore deposits. On this basis, quantitative distribution data and a comprehensive and comprehensible inventory of unit process inputs and outputs as a function of ore compositions and processing technology options can be generated, which is consistent with early design stage information requirements, both in terms of detail and accuracy, ie is æfirst-orderÆ in nature. This predictive approach to element distribution during primary metal production provides decision-makers with key information in the early design stages of a project (in terms of developing processes within the context of sustainability), whilst simultaneously guiding further data collection and environmental impact prediction studies.

Jan 1, 2006

By Emma Arakelova

?2?2 (98 %) vapour passed through a reactor at 25Pa where a Zn? target was placed at 273K- 373?. Experiments were carried out on a flow- type vacuum device. ?2?2 decomposition on Zn? surface accompanied by formation of a Zn-containing volatile complex which transferred to the gas phase, and Zn? deposited on a substrate at condensation. As the substrate, five sequentially located quartz cylinders were used at 293K- 423 K (?n). Decomposition of the Zn-containing complex on quartz substrates carried out as a first- order reaction. ?The complex decomposition constant (??) increased with the substrate temperature (?n=293 K, ??=7.05 sec-1;?n = 373 K, ?? = 87 sec-1;?n = 423 K, ?? =158 sec-1). ?The complex decomposition constant did not practically vary when the target temperature increased; the complex formation rate increased slightly.

Jan 1, 2006

By M. Fafard, D. Picard, J. -F. Bilodeau, G. Soucy

To simulate adequately the behaviour of a Hall-Heroult electrolysis cell, a finite element model must take into account the properties of each material. However, it has some lacking knowledge on the mechanical behaviour of materials, like the long-term visco-elastic (creep/relaxation) behaviour of cathode. A three-dimensional model is then proposed in this paper and will be ready to be implemented in the finite element code FESh++. The model was developed using the three-dimensional model based on thermodynamic of irreversible processes where the choice of the internal variables is based on a phenomenological approach. All parameters of the model are represented by constant constitutive tensors and the temperature and chemical dependencies are taking into account through scalar functions multiplying the constant constitutive tensor. The goal of the first part of this project was to determine the parameters of the threedimensional visco-elastic model at the reference state (virgin material at ambient temperature) of three different cathode materials. This paper presents the theoretical model and the results of creep tests at ambient temperature for the semi-graphitic carbon cathode.

Jan 1, 2006

By G. De Gregoriis, G. E. da Mota, H. P. Dias, J. E. M. Blasques

In recent years, like many other smelters around the world, Albras has been increasing line current. The necessary adjustments to the work practices and process variables need to be made on all potlines, which in this case means on 960 cells at the same time. It was a challenging task to adjust the process parameters to the new amperage. In July 2003 potlines 2, 3 and 4 were running at 1 73 kA and the goal at that time was to reach 180 kA. Preliminary trials with 180 kA were performed on a group of 10 boosted cells on potline 3 in order to investigate possible operational problems. It was decided to increase the amperage in three steps accompanied by continual evaluation of the state of the process. In July 2004 the target of 180 kA was achieved with good operational results. This paper presents the overall results, the parameter adjustments made during the amperage increase in the booster group and how the increase was implemented on the other potlines.

Jan 1, 2006

By W. F. Riggs

1 Flotation Analogy To explain flotation in simpler terms the following analogy will be used. A factory (the flotation cell) manufactures a product (collector coated mineral). The product (collector coated mineral) is transported to market (the launder). A truck (the frother) is used to transport the product (collector coated mineral) to the market (the launder). The truck (the frother) transports the product over a road (the froth bed). The truck (the frother) and product (collector coated mineral) are supported by tires (the air). 2 Assumptions This operating philosophy assumes that the correct collector dosage is present along with the correct particle size distribution, pH conditions, etc. and that the minimum required frother dosage is correct. 3 Collector Addition The collector addition as used at a flotation plant is based on dosage rate as determined by the amount of mineral value entering the concentrator. Collector is normally added at two points in the concentrator: The primary flotation circuit and staged addition in the rougher scavenger circuit. Surveys have shown that the staged collector addition provides an increase in the kinetics and increases the recovery of the valued mineral in the rougher scavenger circuit. 4 Frother 4.1 Frother Dosage As explained in the above analogy, frother can be likened to the truck that transports the product (collector coated mineral) to market (the launder). Just as you would not use a truck rated at 15 tonnes to transport a 20 tonne load, you cannot expect to transport coarse minerals to the launder when there is insufficient frother present. Frother dosage must always be at, or above the minimum target. If less frother than the required minimum is used, then coarse mineral particles will not be supported and transported to launder where the mineral is recovered. To the naked eye the froth characteristics, even when insufficient frother is used, will appear to be correct. You cannot see the coarse particles that are not being recovered in the froth. (See Section 4.2 below for an explanation of why this occurs.)

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 H. Westengen

The AE alloy family exhibits remarkable combinations of properties when utilized as high pressure die castings. This performance relies on the fact that the rapid cooling rate resulting from the direct contact between the molten alloy and the steel die walls effectively refines the structure through rapid solidification. Furthermore, the rare earth additions modify the solidification pattern, dramatically reducing the solidification interval. A solid shell forms at temperatures exceeding 500C, reducing the tendency for die sticking and inverse segregation. As a result, the die castability is excellent, giving parts with a smooth and shiny surface. Unlike other magnesium die casting alloys developed to improve elevated temperature creep properties, AE alloys do not suffer from the commonly observed tendency to introduce brittleness. This feature is attributed to the fact that the massive magnesium- aluminium intermetallic phase is substituted by a finely dispersed lamellar structure of Al-RE intermetallics. The resulting combination of excellent elevated temperature properties and good ductility, as well as excellent corrosion resistance, means superiority of these alloys for demanding automotive engine and chassis applications.

Jan 1, 2006

By Gabriella Tranell

In the manganese ferroalloys industry, there is increasing focus on the performance of different carbonaceous materials within the smelting processes. With a developing scarcity of traditional raw materials, new carbon sources are being identified for potential use in the processes. For this purpose, it is important to be able to predict the suitability of different materials in the process. Hence, the effects of both the physical and chemical properties of the carbon material on the reduction kinetics of manganese and silicon from slag to metal, have been investigated using an advanced sessile drop technique. Using this technique, the reaction patterns of SiO2-MnO containing slag droplets in contact with various solid carbon materials (graphites with different properties as well as cokes and charcoals) at 1400 to 1600\\176;C were studied in-situ. In addition, slag and metal reaction products from kinetic experimental series were analysed. From these results, differences in reactivity between various carbon materials and slags were demonstrated and explained. Mechanisms for both manganese and silicon reduction were proposed.

Jan 1, 2006

By Org de Wet

This paper summarises the strategy for selection between a two module coal plant incorporating large, but less equipment, and a three module coal plant with more but smaller equipment. The two options were evaluated in terms of three main categories: ? Size ? size of the equipment and the effect on the process efficiency as well as the difference in physical dimensions of the plant to accommodate the larger equipment; ? Cost ? capital savings between a two and a three module plant, processing the same ROM (run-of-mine) tons per hour (t/hr); and ? Practicality ? in terms of constructability of the plant, safety of using larger equipment and maintainability of the equipment. Decisions that were taken to reduce the risk associated with size, cost and practicality on the chosen option of a two module plant will be highlighted.

Jan 1, 2006

By Linda Duncan, Trevor Yeomans, Chris Potorieko, Michael Fullam

"NVI Mining’s Myra Falls Operation is a 4,000 mtpd copper/zinc flotation circuit with by product gold of ~28,000 ounces per year. Gold recovery has historically averaged 40-55%, however, a portion of this was recovered in the zinc concentrate and received poor payment. Two Knelson CD-30 Concentrators have been operating in the grinding circuit since 1992, with gravity recovery averaging about 2-5% over that time period.The Myra Falls gravity circuit was one of the very first hard rock mining installations operating in the world with automated Knelsons. The mine has employed a unique and unusual upgrading method for the Knelson concentrate that had never been evaluated as to its efficiency. Recent Gravity Recoverable Gold Testing by McGill University, and mathematical modelling of the Gravity Circuit by Knelson Gravity Solutions indicated the gravity circuit was not living up to its potential. Myra Falls Personnel changed the upgrade system-operating regime, and a complete gravity audit of the grinding circuit was carried out, with the results confirming the initial suspicions. Gravity recovery increased from 5% to 15%, with overall gold recovery improving by 5%.INTRODUCTIONNVI Mining operates a 4000 tpd mine and mill complex on Vancouver Island. The milling circuit consists of open circuit rod milling, closed circuit ball milling, gravity recovery, copper flotation, zinc flotation, and tails disposal. There are two milling circuits, “A” circuit, and “B” circuit."

Jan 1, 2006

By Jelke Dijkstra

This paper presents the results of model pile load tests in a photoelastic material. The soil in this test is represented by an assembly of photoelastically sensitive glass particles, which allows for optical measurements of stresses. In the same test setup, displacements around the pile are measured using digital image correlation (DIC). During the pile installation stresses and strains are recorded. Tests were performed in loose and medium dense particle assemblies. The development of stresses and strains around the pile tip and pile shaft are quantified and presented in this paper. For the loose conditions the results show a small influence on the stress state. For the medium dense conditions a clear stress change is observed.

Jan 1, 2006

By Nikolay Boykov

Subsurface imaging technologies are part of the electromagnetic (EM) geophysical methods. EM technologies such as radio imaging method (RIM), ground penetrating radar (GPR), and drill string radar (DSR) have great application potentials in the mining industry. However, the success for applying the EM methods to subsurface observations is largely dependant on the correct evaluation of the electrical properties (i.e., resistivity and dielectric constant) of the rocks in the domain of interest. The depth of penetration of the EM signal in coal, as well as the electrical contrast between coal and subsurface boundary rocks or anomalies, are critical parameters for any successful radar system. Based on the measured electrical properties of the coal seam, the proper operating frequency of the radar system must be chosen in order to successfully detect features such as the coal-roof rock boundary, dykes, and voids ahead of mining. The electrical properties of the rocks in a coal seam are frequency dependent. Even though there has been a great advancement in the hardware and data processing software in the past twenty years, there have not been many examinations of the high-frequency properties of coal measure rocks. In this paper, the laboratory setups, the testing procedure, and case studies will be presented for a wide spectrum of frequencies for coal measure rock samples collected from various US coal fields. Tests have been conducted to study the different conditions, including moisture content, that affect the EM properties.

Jan 1, 2006

By P Papanastasiou, J Hadjigeorgiou, E Kyriakou

The south west area of Cyprus has a long history of slope instability problems. The location and extent of these landslides has been influenced by ground morphology, geological structure and the presence of weak rocks and cohesive soils. The main triggering mechanisms have been precipitation and/or seismic events. Landslides have contributed to the decision to relocate villages and considerable efforts have been put into maintaining the integrity of the local transportation network. This paper uses a recent case study of road embankment failure near Pentalia in southwest Cyprus to review the available tools for the analysis of slope instability. It further demonstrates how the shear strength reduction technique can be used in a finite element analysis to better visualise the slope instability mechanism of a road embankment and provide a reliable tool in selecting appropriate remedial measures.

Jan 1, 2006

By F. Ajersch, A. R. Hekmat

Apparent viscosities of hypo-eutectic (Al-7% Al) and hyper-eutectic (Al-35% Si) binary alloys were measured in the semi-solid state using a Couette type viscometer at variable shear rates. Analysis of the microstructural evolution demonstrates the differences in the rate and degree of attrition of the primary phase particles which are characteristic of the thixotropic nature of the semi-solid alloy. It was observed that the Si primary phase in the hyper-eutectic alloy is much more difficult to fragment than the dendritic a-Al phase in the hypo-eutectic alloy. For the case of the a-Al, the dendritic structure is broken down by attrition and fracture of the dendrite arms whereas the fracture of the Si hexagonal crystals in the hypereutectic alloy occurs along the {100} and {110} cleavage planes. Results are presented for fixed solid fractions of the primary phase at isotherm condition for each type of alloy.

Jan 1, 2006

By Lifeng Zhang

The transport of fluid, heat and particles (bubbles and solid inclusions) in flowing molten steel is investigated in steel refining ladles, the continuous casting tundish, continuous casting mold and strand, and steel ingot casting processes. Inclusion removal from the molten steel by flow transport and bubble flotation, and inclusion growth by collision and diffusion are discussed. Removal of impurity elements such as [C] and [O] during steel refining are reported.

Jan 1, 2006