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By D. Zaharaki

The optimisation of geopolymer synthesis was studied bymixing low Ca electric arc ferronickel slag with kaolinite, sodium silicate solution, sodium hydroxide pellets and water. The pulp was heated at low temperatures and left for curing at room temperature. Through statistical analysis it was shown that the factors with the most statistically significant effects on the compressive strength of the produced geopolymers are slag particle size and aging period. XRD and FTIR studies provide useful information regarding the progress of geopolymerisation mechanisms. Finally, studies regarding the durability and structural integrity of the produced geopolymers were also carried out.

Jan 1, 2006

By William Porter

Hand scaling is a physically demanding job and is responsible for numerous overexertion injuries in mining. This experiment studied rib scaling from an elevated bucket to examine force generation capabilities and electromyographic responses to a prying subtask. Subjects exerted force using two bars (steel and fiberglass) at five target heights. Work height significantly affected peak prying force during scaling activities with highest force capacity at the lowest level (p = 0.0188). Bar type did not affect force generation (p = 0.7843): However, use of the fiberglass bar required significantly more muscle activity to achieve the same force (p < 0.05). It was concluded that miners should scale points on the rock face that are below their knees, and reposition the bucket as often as necessary to do so. Additional research is needed to fully understand the impact of bar type on the physical demands of an entire scaling task.

Jan 1, 2006

By C J. de Beer

The Kwaggashoek East pit is one of the four production areas of Thabazimbi Iron Ore Mine. The Kwaggashoek East Open pit mines through the abandoned sublevel caving operations of the Kwaggashoek East underground workings. A risk assessment indicated that the primary risk is the occurrence of surface subsidence. Based on local knowledge, a hypothesis, that most of the cavities were filled with broken rock as a result of roof collapse and bulking of failed material was formulated. To test the hypothesis a number of geophysical methods as well as probe drilling was utilized. The results of the resistivity, gravity and ground penetrating radar surveys were inconclusive in determining the position of voids. Either there were no voids present or the resolution of the surveys was not high enough to pick it up. It is accepted that only small voids remained, and that the supported roof hypothesis is valid. As a precautionary measure all the production blast holes within the caving area were over-drilled by forty percent. This would collapse the roof of any small voids or tunnels immediately below the block. This operation proved to be successful as two of the three underground levels have been mined out with no subsidence occurring in the pit floor.

Jan 1, 2006

By Renaud Metz

The DOPA process (Direct Oxidation of a Precursor Alloy) was used to prepare ceramic powders based on doped SnO2 and ZnO. The DOPA process consists essentially in the direct oxidation of a homogeneous precursor alloy. A unique advantage of this process is its rather benign environmental impact since no dangerous reactants are used and no harmful by-products are generated. Only oxygen and the alloy metals participate on the chemical reaction to produce the multi-component oxide. Homogeneous alloys of niobium, cobalt and chromium doped tin have been prepared. The molten metal alloy is atomised in air using a double fluid nozzle to produce metallic powders. A subsequent thermal treatment is carried out to fully oxidise the sprayed metal alloy powders. These raw powders are used to prepare a ceramic powder through a mill homogenisation and atomisation process. The ceramic powder is then uniaxially compacted in disc shape and sintered in an oxidising atmosphere. The resulting sintered bodies are metallised on their flat faces and the cylindrical surface is passivated using lead free glass enamel. These ceramics present excellent semiconducting properties with non-linear (non-ohmic) characteristics. The DOPA process is found to be an attractive procedure to obtain ceramic powders for the preparation of SnO2 varistors.

Jan 1, 2006

By William R. Yernberg

SME’s Arizona Conference was held at the Doubletree Hotel at Reid Park in Tucson on Dec. 4 and 5, 2005. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together once each year to discuss the status of the industry. Important topics discussed among the attendees included the price of copper, community relations and education.

Jan 1, 2006

By V Kveldsvik, N Ragvin, T Eiken, G Grøneng, G V. Ganerød

Catastrophic rock slope failures have caused destructive tsunamis in Norwegian fjords. At the Åknes rock slope the tsunami generating potential is large due to the potential large volume involved in a possible catastrophic failure. Widening of the upper crack has been recorded since 1986, and in recent years, a quite extensive investigation and monitorin campaign has been conducted. Data from some of these investigations are presented and analysed with respect to a preliminary evaluation of the stability of the slope.

Jan 1, 2006

By K Marler

The Water Act 2000 includes provisions to manage the take of overland flow water. Overland flow water is water that runs across the land after rainfall either before it enters a watercourse, after it leaves a watercourse as floodwater, or after it rises to the surface naturally from underground. To ensure adequate environmental flows and long-term security for water users, it is necessary to balance the amount of water taken as overland flow water and the amount left to flow into watercourses. A water resource plan made under the Water Act 2000 establishes the basis for the sustainable management of this type of water. Of the water resource plans that have been prepared for Queensland catchments, six include provisions to manage the take of overland flow water. This paper discusses some of the common features of these plans and the management approaches adopted. The paper identifies and explains key aspects of the Water Act 2000 framework for managing the take of overland flow water by the mining industry. In particular it explains key concepts of this framework, such as the ability to take overland flow water using existing works, uses of overland flow water that a water resource plan permits, situations where a specific entitlement under the Water Act 2000 is required, and the means for controlling works that take overland flow water. Future initiatives for the regulation and management of overland flow water are then identified and particular challenges for the mining industry associated with using overland flow water highlighted.

Jan 1, 2006

By Unknown

Threats to Industry Theft Potential

Jan 1, 2006

By Janet A. Flinn, David G. Fileccia

Machine guidance and control systems have become more pervasive in the mining industry in recent years but not always from mining-experienced providers. Dozers, motor graders, scrapers, excavators, shovels, draglines, drills and haul trucks are just a few examples of the types of heavy machinery now equipped with global positioning system (GPS)-aided guidance systems. While equipment manufacturers are offering their own software, many only supply solutions for the machines they produce. The proliferation of GPS equipment manufacturers entering the machine guidance and control arena has resulted in a multitude of makes and models of GPS receivers. Some of these companies also produce their own guidance software. But they usually just specialize in a narrow range of heavy machinery. So customers are forced to use multiple systems and face new challenges in implementation, training, reporting and inter-system communication.

Jan 1, 2006

By Robert Hopler

The use of electrical fuzes is rapidly superseding the old cap and fuse method of firing blasts. It is therefore desirable that the details of this kind of blasting should be more generally understood

Jan 1, 2006

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By I. Yarita

Magnesium alloys have the lowest density among the metals in practical use, and have properties such high specific strength, electromagnetic interference shielding and good vibration damping. Thus, there are many applications of these materials in automotive and electric parts. However, there is a little use of the products of metal forming of these materials because of poor plastic deformability in the normal temperature range and their high cost of production. To expand the range of application of products manufactured by metal forming, rolling technology for producing thin sheets having good mechanical and surface qualities is required. In this study, hot-rolled Mg-alloy sheets are experimentally rolled with or without lubrication in the temperature range from 293 K to 523 K. Rolling force, plastic deformability and surface quality are investigated, and the grain structures and their uniformity are observed. The effect of friction between the roll and the deforming material on the uniformity of the grain structure is discussed. Moreover, rolled materials are annealed and their mechanical properties are investigated by the tensile test and compared with those of as-rolled materials. The effects of the rolling conditions on the mechanical properties are discussed.

Jan 1, 2006

By D Clarke, R Simpson

The Main lode in the Anwia Gold deposit is difficult to interpret due partly to the fact that three separate grid and drill hole orientations exist over the area and partly due to a lack of understanding of the controls on the high-grade mineralisation. Scattered high gold grades and multiple veining orientations add to the confusion. Sectional interpretations of the lode are often misleading due to the multiple orientations of drilling. Initial attempts to define a high-grade constrained geological model were not successful due to the inability to establish any geological continuity that would hold together in three dimensions. As a consequence the initial geostatistical domaining for the Main lode at Anwia comprised a simple broad mineralised envelope split by the weathering profiles. Subsequently an analysis correlating subjective qualitative logging information with grade plus utilisation of LeapfrogTM software, together with extensive geological re-interpretation resulted in the definition of a coherent high-grade shoot within the Main lode. The resource was re-estimated including this new domain as a high-grade hard boundary. Estimations on both models were carried out using uniform conditioning, which is a recoverable resource estimation methodology that estimates tonnages and metal above a series of cut-offs for SMU (selective mining unit) sized blocks. This paper compares the tonnages and metal contents that are calculated from the two estimation runs, both at a zero cut-off and a series of higher cut-offs. The results confirm that the estimation methodology has been implemented correctly as the tonnage and metal content at zero cut-off is the same for both models. The resource tabulations and grade tonnage curves predicted by the two models highlight the differences that can occur at higher cut-offs when realistic high-grade domaining is implemented. The results also reinforce the point that recoverable resource models are intended to address selectivity issues and are not substitutes for good geological modelling. Recoverable resource techniques, such as uniform conditioning, will not correctly estimate high-grade zones that have not been explicitly modelled.

Jan 1, 2006

By John P. Davis

The use of conventional, circulatory air rotary and fluid rotary, cased and uncased drilling methods in the vicinity of sensitive infrastructure can have deleterious effects on the ground conditions surrounding and supporting structures and the structure itself. Furthermore, the use of these conventional methods offers the engineer or contractor little information about the condition of the subsurface during geotechnical applications. Conversely, sonic drilling measurements and samples can be used to evaluate actual conditions during the progress of exploration and construction across a given site. This paper will discuss the history and properties of sonic drilling and explore case histories of geotechnical applications for the advancement of boreholes within vulnerable structures and on sensitive sites for several recent infrastructure projects ? a tunnel and railroad project, a dam grout curtain project, a bridge micropile exploration project and a tunnel instrumentation project. Project summaries will discuss the advantages realized when the application of sonic drilling techniques demonstrated superior accuracy, quality control, efficiency, productivity, penetrability, waste minimization and adaptability when drilling adjacent to or within existing infrastructure. Finally, the discussion will address the current testing and application of sonic drilling to the installation of micropiles, earth retention anchors, grout injection and instrumentation installation where the quality control benefits provided by the inherent soil cores, measurement while drilling systems, accuracy and non-destructive production drilling features will be advantageous.

Jan 1, 2006

By S. Kamado

Development of new SF6 alternative cover gas with low global warming potential is strongly desired for melting and casting of magnesium alloys. We have tried to apply several kinds of HFC and HFE gases with low potential from 30 to 950 as protection gases to AZ91D alloy melt in the temperature range of 650 to 800°C. As a result, protective film consisted of MgF2 and MgO is formed on the melt surface and ignition-proof effect is sufficiently obtained at all the temperature ranges even when flow rates of mixed gases containing CO2 as a carrier gas are almost the same as those using SF6 gas. Reduction of global warming potential exceeds 98% at 650°C and 89% at 800°C in comparison with a mixed gas of CO2 and SF6.

Jan 1, 2006

By L. A. Cornish, S. N. Prins, R. Süss

The work is being done using the Thermo-CalcTM software, and the database is being built up by obtaining good thermodynamic descriptions of all of the possible phases in the system. The database supplied did not cover all of the phases, and these had to be gleaned from literature, or modelled using experimental data. Similarly, not all of the experimental data were known, and where there were gaps or inconsistencies, experiments had to be undertaken. A preliminary version of the database was constructed from assessed thermodynamic data-sets for the binary systems only. The binary descriptions were combined allowing extrapolation into the ternary systems, and experimental phase equilibrium data were compared with calculated results. Very good agreement was obtained for the Pt-Al-Ru and Pt-Cr-Ru systems, which was encouraging and confirmed that the higher-order systems could be calculated from the binary systems with confidence. Since some of the phase models in databases were different, these phases had to be remodelled. However, more work is ongoing for information concerning the ternary phases present in the Al-Cr-Ru, Pt-Al-Ru (two ternary compounds in each) and Pt-Al-Cr (possibly more than three ternary compounds) systems. At later stage of the work, problems with the thermodynamic descriptions of the Cr-Ru and Pt-Cr binary systems were found. A programme of experimental work to overcome these has been devised, and is being undertaken. Keywords: Pt-based alloys, phase diagram calculations.

Jan 1, 2006

By R. M. Lamya

The leaching behaviour of nickel?copper matte in an acidic?copper sulphate solution during the repulping stage at Impala Platinum Refineries has been studied. The base metal recovery process consists of a matte repulping stage prior to a series of pressure leach stages. Therefore, the repulping stage is basically an atmospheric leach stage in which the matte containing mostly Niand Cu is leached in copper-spent electrolyte from the tank house, resulting in dissolution of nickel and precipitation of almost all the copper. To understand the nature of the leaching process during this stage of the operation, the effects of temperature stirring rate and matte particle size on the rate and extent of base metal dissolution and copper rejection from the solution have been investigated. The leaching mechanism of the matte in the investigated system is alsoproposed.

Jan 1, 2006

By L Chaffey, M Buckland

The minerals industry has enormous potential to positively contribute to sustainable development and many leading companies have concluded that their long-term success is directly linked to their ability to leave a lasting positive legacy. While there are many examples of success, there have been failures as well and much work has been done in recent years to define the role of the minerals industry in sustainable development and identify the key elements for success. In the past, our sector could point to the taxes and royalties it paid, the exports it generated and employment it created and felt confident that its contribution would be recognised and duly acknowledged. This is no longer the case. Critics of the industry have highlighted resource-rich countries that have failed to capitalise on their resource wealth and have arguably lower standards of living than their resource-poor peers û the æresource curseÆ hypothesis. Recent research has done much to clarify the factors that contribute to a countryÆs success or failure and all stakeholders in the industry now need to include these learnings in their approaches going forward. We know that our long-term success relies on embedding a company- wide approach to sustainable development into all aspects of our business operations. In this paper we highlight BHP BillitonÆs experience in the development and implementation of policies and systems designed to enhance our contribution to sustainable development. We detail the business drivers for excellence in this area and the key external codes and initiatives that have shaped our approach. The values-based BHP Billiton Charter, Sustainable Development Policy and associated Health, Safety, Environment and Community (HSEC) Management Standards are central to our approach. Implementation is reviewed through our HSEC audit program. One area in which we have placed particular emphasis is our approach to community development. BHP Billiton has a corporate target to contribute one per cent of its pre-tax profit on a three year rolling average to voluntary community programs. As our profit stream has increased with the minerals boom this is approaching an A$100 million commitment. In our paper we detail how we are working to ensure we maximise the value of this contribution for our communities and our shareholders.

Jan 1, 2006

By K. L. C. Gonçalves, V. K. Alves

"CVRD’s Department of Development and Technology – GETEK has been developing and perfecting a general methodology for scaling up flotation and grinding circuits over several years. This methodology has been applied in several prospective CVRD mining projects. It encompasses a procedure for variability analysis based on bench scale tests, pilot scale grinding and flotation tests and modeling and simulation for scaling up the industrial flowsheet.The bench scale tests include the determination of the Work Index, simplified DWT tests, rougher flotation and locked-cycle tests with samples that are representative of the ore body variability. After completion of these studies, continuous, pilot-scale flotation tests are carried out at a Mini Pilot Plant with drill core samples representative of different stages of the mine life. Finally, studies are carried out with large volume samples using a conventional grinding and flotation pilot plant. This sample is also used for liberation characterization, grinding kinetics, flotation kinetics and industrial circuit scale up. This methodology has been successfully employed in the development of CVRD’s new mining projectINTRODUCTIONCVRD has been developing and perfecting a general methodology for scaling up flotation and grinding circuits over several years. The definition of the processing route and the sizing and scale up of the processing system are some of the products generated during the pre-feasibility of a greenfield project. This paper is focused on the scale up of grinding and flotation circuits, operations known to be of the most importance in a mineral processing plant.The methodology for the definition of the flotation and grinding circuits is divided in the following stages: bench scale ore variability studies, pilot plant operation and modeling followed by simulation. The product of this work is a calibrated simulator that can be utilized for plant operation as well as mine planning, looking to achieve optimal operational conditions.The current models used for scale up of the grinding circuits are aimed at the generating information about the size distribution of the circuit product. However, it is well known that the liberation state of these products may be of critical importance for the performance of the concentration processes downstream. Nevertheless, CVRD has been developing a methodology for liberation kinetics during grinding, aimed at optimizing grinding circuit throughput together with downstream flotation recovery."

Jan 1, 2006

By Fernando Guevara

Many smelting and slag-cleaning furnaces operate with cooling systems designed to freeze a slag layer over the refractory to protect it. The fluid flow and heat transfer conditions associated with the freeze layer and mushy zones are poorly understood. These phenomena were simulated with a small-scale room temperature, 2-dimensional model, using an aqueous solution of calcium chloride to simulate the slag. Reasonable similarity with conditions encountered with copper and nickel smelting systems was achieved (Pr 50 and Ra 108, in the laminar-turbulent transition). Measurements of the freeze layer development and velocities were made with the Particle Image Velocimetry (PIV) technique. Direct Numerical Simulations (DNS) were also made of the unsteady fluid flow and heat transfer problem. It was found that the solidification process is well described using an improved model for high molecular viscosity in the mushy zone. Solid front growth, isothermal profiles, velocity profiles and heat transfer through the walls showed good agreement between the PIV and DNS results. Experimental and numerical velocity profiles close to the freeze layer show a parabolic behaviour in the vertical velocity profile which is completely different from the calculation of heat transfer using a sharp interface model. The reason for this is attributed to the effects of the mushy zone with a high viscosity and high shear stresses acting on that area.

Jan 1, 2006