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By J. Gebhardt, D. McBride, C. R. Bennett, Croft. N., M. Cross

A comprehensive model of solution flow through heap leach systems requires a numerical solution with the ability to predict variably saturated-unsaturated flow through porous media domains that contain materials with spatially variable properties. The types of flow associated with stockpile leach processes lead to flow problems, such as infiltration into dry soil, drainage, perched water tables and flow through heterogeneous materials. Computational methods for modelling this class of flow behaviour are conventionally based on the classical Richards' equation. However, the governing equations are highly non-linear, difficult to solve, and require iterative numerical solution methods. The pressure-based form of the Richards' equation suffers from poor mass balance, while the mixed form can possess convergence difficulties. An adaptive transformed mixed algorithm is described, which reduces the non-linearity of the problem, optimizes the time step size, and provides a fast, numerically robust scheme that significantly reduces computation (or CPU) time. This method is shown to give fast, accurate solutions on a number of complex flow problems. The utility of this algorithm is illustrated through its implementation within the PHYSICA computational modelling software, which incidentally, provides a framework for a comprehensive heap leach model.

Jan 1, 2005

We all live in professional silos û comfort zones, where we talk to like-minded people with the same training, experience and view of the world. We note in passing the existence of other disciplines, but they are tolerated rather than embraced. To the geologist, the metallurgist is a mad scientist conjuring gold out of some foul solution about which the less said the better. To the metallurgist, the geologist is a bearded, self-appointed sage who guesses what is under our feet by sniffing the air, and drives a Land Rover badly. As to the view of mining engineers held by both geologists and metallurgists, this is best left to the imagination. And of course we are all confused by the term æmetallurgistÆ. I am called a metallurgist though my skills are in mineral processing not metal processing, but I canÆt be called a mineralogist because that definition is already taken. *Please note that this is available as an extended abstract only*

Jan 1, 2005

By P. Sauriol

This work addresses the design challenges and demonstrates the capabilities of a novel water transfer factor measurement apparatus. Several measurement concepts were screened on the basis of their water transfer factor accuracy using Monte-Carlo generated virtual experiments. The most promising measurement concept was assembled and tested to assess its actual measurement accuracy. For these concept validation experiments, the polymer electrolyte membrane fuel cell was simulated by adjusting the water injection rate to corresponding levels. Combining the anode and cathode measurements, the water transfer factor accuracy was typically better than 0.01. Real-time measurements of the water transfer factor on both anode and cathode sides of a polymer electrolyte membrane fuel cell were achieved. The anode and cathode side measurements were in good agreement with each other; however the anode side measurements were generally more reproducible. A parametric study showed that stream humidification plays an important part in the water transfer across the membrane electrode assembly. Finally the water transfer factor along the channel of a 300cm2 co-current fuel cell was obtained by using a series of six 50cm2 sub cells. The results were in good agreement with predictions from a recently proposed model.

Jan 1, 2005

CSIRO Minerals, in association with the AJ Parker CRC for Hydrometallurgy, has an active program of hydrometallurgical research in which physical and computational modelling are used to better understand and improve a range of different unit operations. The modelling is based on flow simulation (Computational Fluid Dynamics or CFD), but incorporates other physical and chemical phenomena of importance, such as droplet break-up and coalescence, species transport and reaction. This paper reviews some of the major projects that have been undertaken at CSIRO Minerals and will illustrate the critical importance of hydrodynamics to the performance of unit operations and the improvements that can be made to performance using such modelling techniques. Unit operations that are discussed include solvent-extraction, gravity thickeners, flotation cells, bio-heap leaching and stirred tanks.

Jan 1, 2005

By A. Varma

Successful technology commercialization occurs when a company is focused on creating shareholder value by providing a reliable product at a price point attractive to the market, while at the same time maintaining strict control of its internal cash burn rates. Developing a technology platform and a market platform are equally important in the commercialization of new technologies such as fuel cells. This paper will discuss some of the key barriers that may prevent successful market entry for emerging and disruptive technologies, such as: R&D priorities, supply chain / manufacturing issues, materials, cost reduction strategies, customer needs, developing a market pull strategy, institutional barriers such as existing regulatory/approvals processes and/or current design/purchasing practices, product reliability and resilience, and finding the right path to market. SDTC is an arms length foundation that aims to financially support the successful market entry of emerging and disruptive technologies that can provide significant environmental benefits to Canada. The fuel cell industry, which represents one such technology, is at a critical point in its evolution where market receptivity and the technology platform are converging to potentially create significant customer advantages for fuel cell products being developed today. Since its inception in 2001, SDTC has received over 850 business cases from which it has identified successful strategies to overcome the noted barriers to commercialization. While maintaining commercial confidentiality, the SDTC database will be mined to: Identify specific success stories that have overcome various barriers and discuss their strategy; Identify specific fuel cell related industry experiences that hinder successful market uptake. The general attributes and trends of successful technology developments identified in this paper will hopefully provide guidance to technology developers and prepare them to successfully tackle the next set of hurdles on the path to commercializing their technology, once they have proven their technology works in the laboratory.

Jan 1, 2005

By Sunil S. Basarkar, Dilip M. Dewaikar, Rajesh H. Gajjar

"A load transfer program AXPILE was developed for simulation of the loadmovement characteristics of socketed piles of the Mumbai reg ion. This program used empirical relationships for ultimate shaft resistance at pile-rock interface recommended by Zhang and Einstein (1998). According to their recommendation, ultimate shaft resistance at pile-rock interface is related to the square-root of uniaxial compressive strength of intact socket material by a parameter C, which ranges from 0.4 for smooth sockets to 0.8 for rough sockets. Results of three instrumented pile load tests were compared with the AXPILE generated results. The comparison of analytical and field estimates of the unit shaft resistance confirm the recommendations of Zhang and Einstein (1998) on the unit side shear parameter c,, which was found to be in the range of 0.35 to 0.67.INTRODUCTIONInstrumented pile load tests were carried out on the test piles at the Bandra-Worli sea link project in Mumbai city of western India. High capacity socketed piles were required to take up loads from the superstructure. Hence, in addition to the available toe resistance, an accurate measurement of the shaft resistance in socket portion was desired. The instrumented load tests incorporated Osterbergcell (0-cell) assisted by strain gauge instrumentation to estimate the shaft resistance mobilization in the socket portion.AXPILE load transfer program was developed for load-movement simulation of socketed piles (Basarkar, 2004). The load transfer algorithm based on Coyle and Reese (1966) was incorporated in this program, which used empirical correlations and functions to account for load transfer in piles through shaft and toe resistance.This paper compares the computed unit shaft resistance from the AXPILE program with the measured values recorded from the instrumented pile load test."

Jan 1, 2005

By Hee-suk Yun, Dae-jin Hwang, Jeong-woo Seok, Myoung-mo Kim

"In this paper, the accuracy of the data measured by a newly developed displacement measuring system, DPRMs (Digital Pile Penetration and Rebound Monitoring system) and its applicability as a quality control tool were verified by field measurements of pile penetration and rebound for pile driving performed at 3 construction sites and 1 test site. The DPRMs data were found to be much better than handwork data. A new dynamic formula for pile capacities is proposed uses the results of a pilot dynamic load test and the final pile penetration. The ratios of pile capacities obtained by the new formula to those by the dynamic load test were 94%±7.4% in the contrast with 123±28.3% by the 5S formula and 68±24.0% by Hiley's formula. This result shows the superiority of the new formula. The ratios of the maximum compressive stresses calculated by using DPRMs to those calculated by using PDA (Pile Driving Analyzer) were about 90-110±10%. This result confirms the applicability of DPRMs as an overdriving monitoring tool. Two sets of DPRMs were used to measure the 3-D displacement behavior of a pile head at the test site. The more the pile head moves laterally, the less the final set values were expected because of the loss of driving energy, but this trend was not obvious within the limited data obtained at the test site.INTRODUCTIONPile construction monitoring consists of two parts. In the first part, enough capacity of the pile is secured to stand the design load. In the other part, pile damage during driving is prevented. Although several methods can be applied to achieve the first part, PDA is nearly the only tool for measuring pile stress.Several methods such as a static load test, a dynamic load test, an Osterberg cell, and numerous driving equations can determine the pile capacity. Among them, the static load test and the dynamic load test are most widely used. The static load test is advantageous because it has the highest reliability. The disadvantages are as follows: it is costly and time-consuming. Also, the capacity of the pile under construction cannot be evaluated. The dynamic load test has lower reliability than the static load test, but it is cheaper than the static load test, is reliable enough to determine the pile capacity, can evaluate the capacity of a pile during construction, and can offer information about construction conditions such as the pile integrity and the pi le stress during driving. The dynamic load test takes a relatively short time and is low cost compared with the static load test. However, it is still costly, time-consuming, and unnecessary to apply to all piles in the field as a construction measurement tool. Therefore, driving resistance (blowcounts) is commonly measured to confirm the pile capacity at construction sites."

Jan 1, 2005

The effects of corrosion upon the load bearing capacity and ultimate tensile strength of galvanised friction bolts were determined. Corrosion rates were measured by overcoring of the reinforcement elements in situ. Overcoring was achieved at several sites using a specifically designed overcoring drill rig. This rig has the capacity to drill up to 3.0m long 140- diameter core in any orientation and up to a collar height of 7.0m. The recovered core and friction bolt elements were pull tested in the rock mechanics laboratory at the WA School of Mines (WASM) in order to determine their load-displacement characteristics for various embedment lengths. The friction bolt elements were then analysed for rates of corrosion and tested for their ultimate tensile strength. Relationships were formed between these data and the environmental conditions to which the friction bolts were exposed, in order to determine the major factors affecting the corrosion process and how they affect bolt performance.

Jan 1, 2005

By R Moreby

This paper is a demonstration of the techniques developed during an Australian Coal Association Research Program (ACARP) funded research project aimed to develop aids, principally computer based, to assist mine personnel to more efficiently manage significant incidents in coal mines. These aids include software to aid in the location of the incident, electronic information storage and retrieval, online site emergency response manuals and software to aid in decision-making.

Jan 1, 2005

Most of automotive magnesium applications are presently produced by high-pressure die casting processes, For further expansion of the alloy usage in automobiles, novel-manufacturing processes needs to be developed, In this study, squeeze casting of AM50 alloy was carried out using a hydraulic press with an applied pressure of 70 MPa, Tensile properties and fracture behavior of the squeeze-cast AM50 were characterized in comparison with the die cast counterpart, The squeeze-cast AM50 alloy exhibits virtually no porosity in the microstructure evaluated by optical microscopy, The results of tensile testing indicate that the improved tensile properties for the squeeze-cast samples over the conventional high-pressure die-cast parts, The analysis of tensile behavior shows that the strain-hardening rate during the plastic deformation of the squeeze-cast specimens is constantly higher than that of the die-cast specimens. The SEM fractography evidently reveals the ductile fracture features of the squeeze-cast alloy AM50.

Jan 1, 2005

By Antonio Pineda, Roger K. McLimans, Felicity E. Lloyd

lmenite is a primary ore feed to the DuPont chloride process for the manufacture of titanium diox-ide pigment. We seek to determine ilmenite geochemistry as a function of original source and as-certain which ilmenites have chemistry most amenable to upgrading via iron-leaching (leucoxenization) and that have favorable, with respect to pigment manufacture, trace element content. Ilmenite geochemistry is a function of its primary origin and of subsequent alteration. Heavy mineral sand deposits may contain ilmenite from one or several dominant source rock(s). In addition, ilmenite may alter in the weathering environment, changing the major element compo-sition (iron-leaching) and certain of the minor element content. A primary objective is to classify ilmenites in relation to origin in order to fingerprint source rocks in provenance determination. The changes in trace element chemistry during alteration are also investigated. A “decision tree” is developed to classify ilmenite types and source rock origins. Ultimately, with those methods and by amassing a database of ilmenite types from worldwide locations, it should prove possible to determine ilmenites (and their sources) more susceptible to iron leaching in the weathering en-vironment. Such ilmenites, enhanced in their titanium content, are the preferred ore targets. The method used is electron microprobe analyses at elevated conditions of voltage, cur-rent, and counting time to enable higher precision. In-situ ilmenites from igneous, metamorphic, and altered rocks (saprolites) are analyzed. Initial foci for sedimentary ilmenites are restricted provenance (approaching monogenetic, examples from Spain, Portugal) and polygenetic prove-nance (Denmark). Altered ilmenites, including the DuPont Florida ore, are used to characterize the chemistry of leucoxenization. Trace element concentration, detectability, and cost considera-tion, led to focus on Mn, Mg, V, Cr, and Nb to develop a classification scheme validated by dis-criminant analysis and “classification-regression trees”. Results show a high degree of success for restricted provenance study and an acceptable one for polygenetic provenance.

Jan 1, 2005

By I. Kirman, B. Waters

World wide applications for nickel use will be summarized and examples of those uses given. Nickel products are critical to many important aspects of modern society. These products are just as important for modern China as they are in other parts of the world. It is argued that future pattern of nickel use in China should be expected to be very similar to that in the rest of the developed world. Total use of nickel in products in China is already very large. In 2004, it was the largest market for stainless steel (nickel containing) in the world. A survey of Chinese stainless steel applications will be presented. Current high nickel prices have revived speculation about substitution, particularly for nickel containing stainless steels. The presentation will discuss some of the complicating factors that need to be taken into account when considering substitution. These factors are as valid in modern China as they are in other developed economies. Recent substitution efforts and the reaction to them will be examined. The Nickel Institute position regarding appropriate application of the various grades of stainless steel will be discussed. Price-motivated substitution in China, and elsewhere, will occur but it is argued that the extent will probably be limited.

Jan 1, 2005

Declines for both access and rock haulage are replacing shafts for mining relatively shallow deposits of down to 1000 m below surface. Where the orebody does not outcrop and where surface access may be restricted, it is often necessary to drive long dead end headings before a connection can be made back to surface and a ventilation circuit created. In hot tropical areas and where large diesel powered equipment is used for mining, heat may also be a problem at these relatively shallow depths. The normal design criteria based on statutory limits and good practice used to evaluate ventilation and cooling requirements in terms of air velocity, dust, gases, diesel exhaust dilution, re-entry after blasting and heat stress are described in this paper. These are then used to design and cost alternative auxiliary ventilation systems that include leakage based on general fan performance curves and typical duct systems. The implications of the current European Community recommendations regarding nitrous fumes are also briefly considered. The actual problem relates to a 2100 m long decline that may have to be extended to 3000 m long without a connection to surface or through ventilation and is located in a hot tropical area where the surface wet bulb temperatures may exceed 25¦C for more than a third of the summer period. Once the preliminary ventilation design is completed, the auxiliary ventilation system can be modelled and simulations undertaken that incorporate heat and moisture transfer routines with the objective of determining the cooling load and amount of refrigeration required. Cognisance is taken of cyclic diesel operations and the thermal flywheel effect of the surrounding rock on the wet and dry bulb temperatures resulting from these operations.A suitable modular cooling system located at the portal is described and optimised with capital and operating costs of both the ventilation and cooling systems provided.

Jan 1, 2005

By Charles G. Weakly, Alan M. Lander, Pamela B. Zohar, Robert W. Leonardson

The cluster of gold deposits at the Goldstrike property is located in the Northern Carlin Trend in northeastern Nevada (Fig. 1). At many mature mining camps like Goldstrike, exploration innovation and success may wane with time. In this regard, sufficient exploration drilling was conducted in the area immediately north of the ultimate pit crest and under the final planned pit wall to test for a major deposit. No indications of large deposits were found, however, the majority of drill holes did intercept mineralization. Mining along the northern pit wall exposed significant structurally controlled ore-grade mineralization that had been missed by exploration drilling. In 2002 and early 2003, the mine geology group added reserves to the pit and improved the definition of underground resources by targeting specific ore-controlling structures within favorable stratigraphic units by utilizing relatively inexpensive horizontal RC drilling from the pit wall. The widespread occurrence of mineralization to the north of the pit was re-interpreted to be an indication of continuity of these mineralized zones. In January 2003, 70 feet of 0.332 opt Au at a depth of 710 to 780 feet was intercepted in a dewatering well. This intercept was significantly thicker and higher-grade than average for the area, which confirmed the existence of high-grade structural continuity, and helped secure management support for additional exploration. A timely and cost effective solution was needed to confirm the potential of the area. Immediate follow-up drilling on tighter grid spacing was rejected in favor of improving the geology model. Exploration across the property would benefit from an improved geology model, but to provide results in a timely manner, the area to the north of the Betze pit was chosen as a starting point (Fig. 2).

Jan 1, 2005

By Charles M. Wilk

"Solidification/stabilization (S/S) treatment is used to treat hazardous wastes for disposal and in the remediation/site restoration of contaminated land . SIS is also an increasingly popular technology for Brownfield (industrial property) redevelopment, since treated wastes can often be left on-site and to improve the soil for subsequent construction. This paper discusses the applicability of the technology to various wastes, basic cement chemistry relating to SIS, tests used to design treatability studies and to verify treatment, basics on implementation of the technology in the field , and examples of SIS use at brownfield sites, including a former wood preserving site, former manufactured gas plant sites, a former electric generating station, and a shopping mall development.INTRODUCTIONSolidification/Stabilization (S/S) is a widely used treatment for the management/disposal of a broad range of contaminated media and wastes; particularly those contaminated with substances classified as hazardous in the United States. The treatment involves mixing a binding reagent into the contaminated media or waste. The treatment protects human health and the environment by immobilizing contaminants within the treated material. Immobilization within the treated material prevents migration of the contaminants to human, animal and plant receptors. SIS treatment has been used to treat radioactive wastes since the 1950s and hazardous waste since the 1970's (Conner 1990). SIS continues as a cornerstone treatment technology for the management of radioactive waste, hazardous waste, and site remediation and Brownfield redevelopment."

Jan 1, 2005

By N. Djilali

Many of the transport phenomena encountered in proton exchange membrane fuel cells occur intrinsically at the microscale level. Physically representative models that fully account for the salient physico-chemical and transport processes in PEM fuel cells are necessary to achieve truly predictive models that can be used with confidence to: (i) gain a better understanding of in-situ processes and couplings, (ii) explore new concepts, and (iii) support design and optimization. The development of more general, rationally based macroscale models requires use of knowledge on the microscale level to provide guidance, and to determine the required parameters and coefficients (model "constants"). In this paper we present a new membrane transport model, the binary friction membrane model (BFM2), recently developed to account for coupled protonic and water transport in polymer membranes. This general model is based on rational and physical consideration, removes several of the limitations of the empirical models used to date, and is formulated for all purfluoro-sulfonic acid membranes. The use of the BFM2 in a fuel cell model is illustrated highlighting significant performance predictions compared to existing empirical model. The second part of the paper addresses the fundamentals of two-phase transport in hydrophobic gad diffusion media. Computational and experimental visualizations resolving the microscale dynamics of water transport between the fibres of a GDL are presented, revealing transport mechanisms that are, contrary to assumptions used to date, dominated by fingering and channeling.

Jan 1, 2005

By Andrea Gambi, Giancarlo Olivucci, Maurizio Lenzi

"In the paper a criterion for the evaluation of the sharing of the lateral loads in a piled foundation is presented. It relies on the the compatibility condition between the rotation of the rigid pile cap and the rotations of the pile heads, following in that the criterion suggested by the Eurocode 8 - Part 5. This assumption leads to an analytical solutions which allows to deal with the sharing of the lateral loads and moments by means of two main interaction parameters only. A sharing domain is also derived and it shows the role played by the eccentricity of the lateral load on the values of the axial forces and of the bending moments at the head of the piles.INTRODUCTIONIt is well known that the interaction among soil, piles and foundation is one of the most complex subject to deal with in Geotechnical Engineering. Its rigorous study needs to employ suitable finite element software nowadays available and able to take into account the non linear behavior of the soil as a continuum and the inelastic response of the structure. A deep insight to the topic of the sharing of the loads cannot obviously renounce to this approach.On the other hand it is a daily need of the designers to have at their disposal simple tools that allow to make preliminary evaluations of the basic equilibrium conditions. To this purpose many methods of analysis have been developed in the past to face the sharing of the loads in a simplified version. The present contribution follows this way trying however to introduce some improvements that leads to find a solution that satisfies both the equilibrium of the forces and the compatibility of the movements (Lenzi, Gambi, Olivucci, 2002). The proposed model allows to identify the basic parameters which govern the sharing of the lateral load and it allows to perform also parametric analysis and quick checks that may be useful in the design of the piles."

Jan 1, 2005

By Nick Rose, Robert Sharon, Mark Rantapaa

Development of the Northeast Layback of Barrick’s Betze-Post open pit commenced in June 2000 and was successfully completed to a height of 400m (1,300 ft) in January 2003. Following a brief exploration drilling campaign at the toe of the final slope, in-pit waste rock backfilling commenced, which will ultimately buttress the final wall. Instability initially occurred in late 2000, above the 5040 Level, as the slope height approached 120m (400 ft). As mining reached the 4680 Level, significant deformation was experienced over a slope height of 230m (760 ft). Slope stability was managed and targeted reserve recovery was achieved by executing complicated modifications of the mine plan, including splitting layback development, well placed offloading cuts, step-outs and mid-slope waste rock buttresses. Decision on timing of these modifying events was often dictated by review of deformation magnitudes and rates determined from continuous slope monitoring records. Design modifications were developed through continuing interpretive refinement of structural geology controls and groundwater distribution, and through stability re-assessments. This document presents an overview of the geological setting and material and strength conditions of the northeast sector of the Betze-Post open pit, followed by development experience leading to design and development of the Northeast Layback. Rock mechanics modeling, design details and geotechnical performance monitoring are then presented. Development experience, stabilizing adjustments to the original design and safety procedures for development and exploration activities are described. The document is finalized with conclusions and acknowledgements.

Jan 1, 2005

By M. Kozlowski, I. Candy, S. Kashani-Nejad

The production of ferronickel and matte from nickel laterite ores is dominated by the Rotary Kiln, Electric Furnace (RKEF) process. Over time, major improvements have been made to kiln operation. In particular, kilns are now required to perform substantial amounts of reduction of the metallic oxides, thereby reducing the load on the electric furnace and substituting less expensive fossil fuel for electrical energy. To the basic refractory lined cylinder have been added: internal features such as dams and lifters, aimed at changing residence times in different sections of the kiln and enhancing gas/solids interaction, on-board fans to introduce tertiary air and on-board scoop mechanisms to allow reductant coal additions to be made at advantageous locations along the kiln. Many of these advances in design have been made on a trial and error basis and by 'borrowing' technology from related kiln processes, supplemented by proprietary modeling to various levels of sophistication. This paper presents a conceptual review of modeling components for the development of a computational model for granular material flow, combustion and heat and mass transfer in a nickel laterite kiln. These components include: granular material flow and segregation models for the simulation of bed motion, heat transfer models that simulate heat transfer by turbulent diffusion and radiation and the distribution of this thermal energy within the bed, and fluid flow models for the prediction of combustion aerodynamics.

Jan 1, 2005

By Leslie Taylor, R. Reed Skagga, William Gault

The ultimate aim of our overall task, of which the effort described in this paper is a part, is to be able to model the impulsive output of buried charges and the response of targets of interest. It is not practical or cost-effective to determine the response of all targets of interest to buried charges of all sizes by testing them. In order to have confidence in our models, however, they must be validated by a modest number of tests. A critical element in modeling the response of a target is the ability to model the loading function. The load a buried charge applies to a target above it when the charge detonates can be characterized in terms of the vertical impulse. The vertical impulse is a function of the size of the charge, its depth of burial, and the properties of the soil in which it is buried. The primary objective of the effort described in this paper is to determine the load a known charge places on a non-responding target so the data can be used to validate our models.

Jan 1, 2005