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The Pilbara region, located in the north-west of Western Australia, is significant as the second-largest source of iron ore on the planet. Iron ore mines owned and operated by Pilbara Iron are located within the Hamersley Basin. This paper refers to the Greater Paraburdoo mines, the 4WEST and 4EAST pits, located on the southern margin of the Hamersley Basin. The groundwater model refers to ephemeral watercourses: Seven Mile and Pirraburdoo creeks, which are adjacent to the two pits, and Ratty Springs, located upstream from 4WEST and within Pirraburdoo creek. The spring and creeks hold cultural heritage significance for local Aboriginal communities. Two of these, the Gobawarrah Minduarra Yinhawanga (GMY) and Innawonga native title claim groups, initiated hydrological work on the two creeks and Ratty Springs, with the aim of determining the affects of dewatering on the natural water flows of these systems. The numerical model used to simulate drawdown in the Pirraburdoo and Seven Mile Creeks was derived from PMWIN Pro software and covered an area of 77 km2. The modelling period was from January 1998 to December 2004, and the prediction period was from January 2005 to December 2015. The model has four layers and incorporated effects caused by mining voids, 4WEST and 4EAST pits, creek bed material, weathered bedrock below creeks and surrounding banded iron formations (BIF). The model has been calibrated using the trial-and-error method set down by Middelmis et al (2001). The current dewatering schedule (12 ML/day) in the 4WEST and 4EAST mining areas does not affect the water table levels in the adjacent creeks significantly or for any considerable periods of time. However, changes to mine plans may occur, for example, in response to changed commodity price and may lead to significant increase in rates of vertical advancement. This, in turn, affects dewatering schedules, as greater vertical advancement requires increased dewatering effort. When an accelerated mine plan is applied to the model and dewatering rates increased to 18 ML/day, drawdowns in the creeks are more noticeable. The model has therefore helped to indicate the extent to which increased dewatering rates may be acceptable, especially in terms of immediate and longer-term damage to riparian species, ie Melaleuca and Eucalypt. Predictions from the model may also allow mine planners to schedule decreased rates of vertical advancement, where these are required to meet environmental constraints.

Jan 1, 2006

By K. U. Kainer

Magnesium and its alloys as the lightest available construction metal offer a wide range of opportunities for the usage in transportation industries, especially Magnesium wrought alloys with their improved mechanical properties show a high potential for structural applications, While magnesium cast components have found their application the interest is now spreading to wrought alloys due to the possibility to get even more homogeneous and better properties compared to cast parts, Therefore alloy and process development especially for extruded and sheet material is a main concern to enhance the application of Magnesium wrought alloys, Castings are still form the majority of applications of magnesium alloys, although efforts to develop adequate wrought alloys have increased, In the presentation, the alloy requirements for processing of cast and wrought alloys will be discussed, The various processing routes and alloy compositions result in specific microstructures and properties which determine the potential use of these alloys, Today, the spectrum of available alloys covers standard alloys as well as alloys for use at elevated temperatures, The trend will be to further diversify the alloy compositions and to improve the alloy properties, Areas of concern still remain the wrought processing and the high temperature (creep) and corrosion properties of magnesium alloys, Examples of recent developments in these sectors will be given, The presentation will also provide an overview of the historical and current use of magnesium and an outlook on future applications.

Jan 1, 2006

As part of the response to the increased demand for products such as iron ore, coal and gold many resource companies have identified the need to develop strategies focused on attracting high demand professionals and retaining current employees in the business. Recent graduates are entering a time where they can expect high starting salaries, attractive benefits and lifestyle options. At the same time high work expectations and large demands on both personal and professional development will also be the norm. Some of the challenges faced may include high demands on performance, working with limited resources, long hours, and tackling unfamiliar areas of work with little guidance. However, managing your career and these challenges effectively can give you valuable experience in a short amount of time. By offering situations from my relatively short, yet active, career in the mining industry during these boom times I will raise some key points on how to best leverage your commodity and make the most of a bullish market.

Jan 1, 2006

Accurate geometric models of orebodies establish the framework for reliable mineral resource estimates that provide a basis for further exploration and mine planning, as well as for financial models that ultimately determine the economic viability of a deposit. Traditional, explicit geometric modelling techniques that are utilised for resource modelling by the general mining software packages, such as MineSight«, involve manually digitising interpreted ore outlines that must be carefully linked to create valid geometric solid models. An alternative, implicit modelling method, employed by LeapfrogTM software relies on a fast method of global interpolation, which offers several advantages over traditional modelling techniques. Although previous case studies have documented the relative efficiencies of the two approaches, the accuracy of the two methods has not been previously quantified and compared. This study quantifies the accuracy of solid models created using explicit and implicit methods, and compares the differences between the models. Solid models of the Doris Hinge vein gold deposit (located in the Hope Bay district, Nunavut, Canada) are constructed from preliminary and follow-up drilling data using both modelling techniques. The accuracies of the solid models generated using preliminary drilling data are determined by measuring the 3D distance between the surface of the models and the actual contact location defined by the follow-up drilling data. Additional comparisons based on volume, cross-sectional area and surface differences were made between both phase 1 solid models and solid models constructed from phase 2 drilling information. The overall results of this study find that the MineSight« and LeapfrogTM solid model accuracies are virtually the same, and that their volume, cross-sectional area, and surface differences are comparable. This study concludes that the implicit modelling technique generates accurate solid models that can be used in place of explicit models as ore shells for resource estimation in certain circumstances.

Jan 1, 2006

By V. C. Pandolfelli, L. Paulino, C. E. Zangiacomi

The continuous improvement in aluminum industry over the last years has increased metal output at lower cost. The potlining plays an important role in this regard due to high cost involved and more recently in its environmental aspects. In order to increase potlife and thus minimize the aluminum cash cost, a systemic approach is needed, through investigating the main cathode failure mechanisms by using a pot autopsy as a powerful tool, and then making the necessary chances to achieve extended potlife. In addition, preheating and pot start-up may also damage the cathode if not performed with an appropriate technique or even if the lining materials are not specified correctly, among other factors. All these aspects will be presented and discussed in this paper. Increased potlife, especially now that the current is reaching values up to 300kA, will allow aluminum plants to match their goals more efficiently at lower costs.

Jan 1, 2006

By A. Noël, R. Lapierre, M. Provencher

"Modem aluminum smelters are facing significant operating cost pressure. Key methods used by smelters to manage this pressure are automation and production-information systems to optimize processes, manage quality, anticipate problems and reduce operating costs. In 2002, Aluminerie Alouette Inc. began its Phase II Expansion project, and retained the joint venture of SNC-Lavalin and Hatch (SLH) as its engineering, procurement and construction management (EPCM) team. Alouette had the distinction of being one of the most efficient aluminum smelters in the world. Alouette already understood the importance of systems integration in project delivery. For Phase II, key objectives were identified to ensure ""a state of the art"" integrated architecture that would support Alouette's production goals to integrate the existing facilities with the expansion, to form a single efficient facility and meet project schedule and budget targets. Achieving those objectives within the context of a large project often creates major challenges due to the nature of the traditional EPCM delivery model, which relies on several vendors and third-party-systems integrators. In this case, an integrated Alouette-SLH team was made responsible for all aspects of the systems integration, taking over the task from most suppliers. The integrated team was responsible for delivering an automation system and plant-wide-production IT system for the new facilities while accommodating migration for the existing systems. Through the use of rigorous methodology and advanced state of the art technology, the IT and automation strategy led to significant value creation and is recognized today as one of the key factors of the project's success. The primary results were: fast and efficient start-up of facilities, due to quality programming and implementation; a plant able to operate as a single entity; automation and IT systems delivered before time and under budget; standard programming methods implemented throughout the plant; and reduced and simplified maintenance."

Jan 1, 2006

By K. E. Barnes

"The “Jameson Cell” flotation cell was developed at Mount Isa Mines in the late 1980’s to address deficiencies in our flotation column installations. Early base metal installations had a variable record. The test work and trials showed they made an improvement metallurgically when operated correctly, but performance of the early installations was hindered by a range of operational and maintenance issues. The installations needed to be more robust, and we needed a better understanding of how to successfully integrate the cells into the plant flow sheet.During the 1990’s, Jameson Cells had great success in coal fines flotation and organic removal in SXEW applications, and became the standard in these applications in Australia. These installations improved the cell design and materials of construction and the cell flow sheet design, to make it low wear with self-regulating control, producing good performance with little operator input.These improvements have enabled a fresh look at the use of Jameson Cells in base metals. Recent new installations have shown significant benefits in “hybrid” circuits, that combine the best features of both Jameson Cells and conventional flotation cells, achieving better overall circuit performance in a smaller footprint than either technology could do by itself.Case studies of successful base metal applications are discussed, using size-by-size mineralogical performance to explain the improved circuit performance. The new methods of flow sheet test work design are also described."

Jan 1, 2006

By Jeffrey R. Hill

To extend the life of the Merchants Railroad Bridge crossing the Mississippi River in St. Louis, MO, the owner implemented a rehabilitation and reconstruction project. The Merchants Bridge provides a key link in the transcontinental railroad system. The bridge is of local importance to the Terminal Railroad Association ? providing a link between St Louis and a rail switching yard in Venice, IL. The intent of the bridge rehabilitation is to keep the Merchants Bridge in service, even though the bridge was originally constructed in the 1890?s. The project involved replacing the East and West approach deck truss spans with new deck girder spans. The rehabilitation program required construction of new concrete piers to support the new spans. In order to reduce the track down time to two, ten day single track shutdowns, the specifications required that all foundation and substructure work be completed while leaving the existing spans in place. The preliminary bridge design specified rock-socketed drilled shaft foundations. Drilled shafts proved to be challenging due to working from beneath the existing bridge, a high water table, utilities, a flood wall, and existing rail way lines. The micropile alternative was technically appropriate given the access limitations, shortened the foundation rehabilitation schedule by several weeks, and realized a significant cost savings to the Owner.

Jan 1, 2006

By C. Kuehmann, B. Tufts

QuesTek Innovations has applied its Materials by Design® methodology to computationally design a new ultra high-strength corrosion resistant steel. Ferriurn® S53 eliminates the need for toxic cadmium coatings currently used on conventional steels in landing gear systems. S53 has the strength of 300M steel, and corrosion resistance similar to 15-5PH stainless steel. S53's corrosion resistance improves stress corrosion cracking resistance and reduces susceptibility to hydrogen embrittlement, improving component reliability and providing an opportunity for extended overhaul and repair intervals. Ultimate tensile stress is 1965 to 2000MPa. S53 was designed to be mechanically equivalent to 300M, with the key addition of intrinsic corrosion resistance. Alloy design, microstructural characterization, and mechanical properties are discussed herein.

Jan 1, 2006

By W. G. Pariseau

Introduction Caverns of 50 m in linear dimension at depths below 2300 m with a life of more than 25 years are proposed for the next generation of water-filled neutrino detectors. Little precedent exists for excavations in such an extreme environment, although some guidance is available from mining experience at great depths, for example, in South Africa, in Canada and at the former Homestake Mine in the U.S.A. Unlike mining for ore, there are choices available in the construction of such caverns that may mean the difference between success and failure. These choices should be informed by rock engineering principles. Recently proposed guidelines for orientation of brick-shaped caverns where the long dimension is a small multiple of the short dimension indicate that the most favorable orientation is with the long and short dimensions parallel to major and minor preexcavation principal stresses (Pariseau, 2005). Numerical analyses at reduced strength indicate some yielding at cavern walls should be expected but that an equilibrium state is quite possible and is aided by arching the back into a spherical dome when the cavern is an empty cylinder (Tesarik and others, 2002). The same indications of stability occur with brick-shaped caverns. However, the most dangerous situation occurs during the excavation sequence to final cavern dimensions. There are any number of excavation sequences that lead to the same final cavern shape, so there is an opportunity to partially optimize the sequence with construction guidelines that minimize peak stress concentrations during construction. This contribution discusses three practical excavation sequences that lead to the same brick-shaped cavern in the strong, massive Yates formation at the Homestake Mine where considerable rock mechanics data has accumulated through the years(e.g., Pariseau, 1985, Pariseau and others, 1995) and where actual mining on the 8000 Level indicates a strong possibility of successful investment in the next generation of large, deep neutrino detectors. The main results are: (1) a favorable brick-shape is one with dimensions in the same proportion as the preexcavation principal stresses (compressionpositive), and (2) favorable orientation of the most extreme but temporary shape of excavation is also best for the construction sequence. Analysis results from a mix of Homestake Mine data and possible excavation geometry illustrate the advantages of these guidelines.

Jan 1, 2006

For Australian mining projects, sustainable groundwater use is typically defined as a groundwater extraction regime, measured over a specified planning time frame, which allows acceptable levels of stress and protects dependent economic, social and environmental values (DEH, 2004). This principle is compatible with most stakeholdersÆ understanding of our national environmental objectives, yet the application of this policy on a project-specific scale is not always straightforward. Three examples of sustainability issues in the management of groundwater in mining are presented. These examples highlight each of the three dependent values: environmental, economic and social.

Jan 1, 2006

By K. Östcrdahl

We are developing a cost-saving and environmentally friendly process with low energy consumption to recover the metal content and recycle the acid from spent pickle baths. The metals are precipitated as metal fluorides, which can be turned into metal oxides and hydrofluoric acid by thermal hydrolysis. In the proposed process the solution is concentrated by nanofiltration and the metals are precipitated in a subsequent crystallization step. Different nanofiltration membranes have been evaluated in experimental batch tests. The membrane MPF-34 from Koch Membrane Systems offered both good flux and acceptable metal retention even after long periods of acid storage. The solubility of B-FeF3.3H20 has been measured at varying acid concentrations and at different temperatures. The solubility decreases with increasing hydrofluoric acid and nitric acid concentrations. This suggests that the crystallization process should be operated at high acid concentrations. The crystal growth rate of B-FeF3.3H2O is found to be quite low but increases significantly with temperature. This suggests that the crystallization process should be operated at higher temperatures (40 - 60°C). Within the project a pilot plant has been constructed where the spent pickle bath solution is concentrated by nanofiltration to the desired metal fluoride supersaturation, and B-FeF3.3H2O is crystallized in a 10 L continuous crystallizer.

Jan 1, 2006

By S. Minamiguchi

Grain refinement is effective to enhance strength and ductility of metallic materials. However this advantage has not been utilized fully for magnesium alloys in industry because microstructure control through thermomechanical treatment is difficult owing to their poor deformability. The authors proposed a high-speed heavy-reduction rolling for production of Mg alloy sheets. It was found that the deformability is significantly improved at high speed and that the thickness can be reduced 60% by one-pass operation even at room temperature without fracture at the rolling speed higher than 1000 m/min. In this study, commercial AZ31B sheets were rolled at 2000 m/min between room temperature and 350°C, and quenched immediately after the rolling. The sheets rolled at 200°C show the finest recrystallized microstructure with the mean grain size of 2.2 Rm. They show outstanding mechanical properties with the tensile strength of 293 MPa, and the elongation of 25%. It is concluded that high-speed rolling is very advantageous for grain refinement and improvement in mechanical properties as well as deformability and productivity.

Jan 1, 2006

By H. J. Ni, M. Y. Huang, S. W. Chen

The effects of several fluxes on purification, microstructures and properties of A00 aluminium have been studied. The experimental results and analyses indicate that many cracks and large porosities exist in the surface film above the melt purified by C2Cl6 and that the film is floe and mostly composed of AhO3 and pure aluminum, which carries many carbon particles and AlCh not fully volatilized. And then over 50% of the all-melting residue is pure aluminum, which is one of the major reasons for high melting loss. Moreover, because of a mass of gas bubbles and a state of seethe, there exist many inclusions which size is under l0µm in the microstructure of A00 aluminum purified with C2Cl6 or fluxes containing C2Cl6- With this purifying method, the aluminum crystal grains are extended along the radius that was observed firstly and the average crystal size of A00 aluminum are about 100µm~150µm. In addition, small size inclusions have little affected on tensile strength and micro inclusions under l0µm have little affected on elongation.

Jan 1, 2006

This paper describes basic parameters, such as surface forces and film elasticity, affecting the stability of foams (two-phase froths). We used the thin film pressure balance (TFPB) technique to measure the surface forces in foam films stabilized with various frothers such as pentanol, octanol, methyl isobutyl carbinol (MIBC), and polypropylene glycol (PPG). The results were compared with the foam stabilities measured experimentally and the film elasticities calculated using a new model developed by Wang and Yoon (2006). It was found that at low electrolyte (NaCI) concentrations foam stability is controlled by both film elasticity and surface forces (or disjoining pressure), the relative contributions from each changing with frother type and concentration. Further, the kinetics of film thinning was studied at a high electrolyte concentration. The results obtained in the present work showed that the major role of a frother is to decrease the hydrophobic force rather than to increase the film elasticity. This conclusion is drawn from the observation that at the typical frother (MIBC) concentrations employed in flotation, frother additions cause sharp decreases in hydrophobic force while causing relatively little changes in film elasticity.

Jan 1, 2006

Exploring long-term future possibilities for your business and methods for achieving them are critical functions of leadership. More than ever, strategic initiatives today have to be planned and delivered in an environment of disruptive change û driven by shifting business or regulatory imperatives, new technologies and global economic change, and diverse stakeholder interests. The notion of The Future as a single inevitable outcome is obsolete. There are many possible futures. This paper explains an innovative process û known as scenario planning û to help executives in the construction and testing of longer-term strategies to deal with uncertainty.

Jan 1, 2006

Classification within the Inferred Resource category is based on geological judgement and the balance of extrapolation versus interpolation that the Competent Person is prepared to accept. These resources are typically drilled at spacings well in excess of the geostatistical range and at a density that is non-uniform. In many cases, a substantial proportion of the available data will be historical, and should be considered with more recent data sources. The provision of a robust geological model will increase the confidence in any resource estimate, and should be viewed as a critical component. The definition of Inferred Resources is of great importance to vein gold projects, since Indicated and Measured Resources generally require costly underground development for delineation. Indeed, many gold vein operations possess substantial quantities of Inferred Resources (>75 per cent) in their resource inventory both at project start-up and during production. This contribution explores a number of the key issues when using the Inferred Resource category and presents four recent case studies.

Jan 1, 2006

By C. J. Brown

Regeneration of hydrochloric acid steel pickle liquors has traditionally been accomplished by pyrohydrolysis. However, a number of factors have recently conspired to reduce the attractiveness of this approach. Moreover, the process is not amenable to small-scale operations. On the other hand, the standard technique for regeneration of sulfuric acid pickle liquors, which is the low-temperature crystallization of ferrous sulfate is applicable to any size operation. A similar technique has recently been developed to regenerate hydrochloric acid. Sulfuric acid is added to the ferrous chloride-bearing spent HCl pickle liquor. The temperature is then reduced to below 0°C, resulting in the crystallization of ferrous sulfate heptahydrate and liberation of free hydrochloric acid. Depending upon the crystallization temperature, variable concentrations of sulfate are left in the regenerated acid. Although this residual sulfate has an impact on the pickling characteristics of the regenerated acid, tests have shown that by adjusting the conditions, pickling rates will be at least equal to those using pure HCI, and an acceptable surface finish will be produced.

Jan 1, 2006

By Satish Kate

Indian limestone mines which are highly mechanized in operation and supply limestone to the cement plants have been quite successful in devising ways and means to optimize blasting parameters, so as to have best fragmentation, powder factor, and cost of excavation. In primary blasting mechanized or manually mixed ammonium nitrate Fuel Oil is quite popular in dry holes, and in case of watery holes conventional packaged slurry/emulsions are being used. In order to avail the low density characteristics of the ANFO, some limestone mines have also used Saw Dust and Rice Husk along with ANFO. A number of field trials have been undertaken to explore the suitability of mixing rice-husk and saw dust with ANFO. Presently, about 10% of rice husk/saw dust is being used only to expand the explosive column. The main technical consideration for the use of saw dust/rice husk, has been to reduce the final density and increase the occupancy of explosive in the blast-hole. This not only lowers the detonation pressure in the blast holes, but also reduces cost of explosive without compromising on the fragmentation quality. Besides, with sleeping of the charge there is no substantial fall in the blast quality.

Jan 1, 2006

By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006