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By Roland Hoet, Jim Patilla, Nick Madison

Increasing conveyor capacity and reliability is a common goal for many underground mines. This task is especially challenging when you must work with existing structure, belt, etc. Meeting this challenge, The Pittsburgh & Midway Coal Mining Co. North River Mine switched from constant fill to actively controlled fluid couplings, realizing a capacity increase from 2,100 tons per hour (2,300 stph) to 2,550 tons per hour (2,800 stph), with improved reliability. This paper will present a case study of The Pittsburgh & Midway Coal Mining Co.'s North River Mine underground conveyor haulage system. These conveyors included the main line conveyors as well as a tension controlled tripper booster panel conveyor. Characteristics and performance of the coupling and control system will be illustrated, demonstrating the systems controllability, simplicity, and dependability.

Jan 1, 2002

By Sung Wng Kim

The binary antimonide compounds with the skutterudite structure have a potential for thermoelectric applications because of the high carrier mobility, high thermoelectric power, and relatively low thermal conductivity due to the complex crystal structure. However, the room temperature thermal conductivity of these skutterudite materials is as high as about IOW/mK with an estimated 80-90% contribution from the lattice thermal conductivity. Because the lattice thermal conductivity of related ternary skutterudite compounds can be substantially reduced due to the additional phonon scattering, a study of thermoelectric properties of these compounds is of interest. The binary IrSb3, ternary Ir1.xRuxSb3 and Ir(MxSb1.x)3(M=Ge, Sn) compounds were prepared by hot pressing of pre-reacted powders. We have measured the electrical resistivity, thermoelectric power, and thermal conductivity, in a temperature range from room temperature to 973K. The binary IrSb3 compound is found to have P-type electrical properties exhibiting a good Seebeck coefficient (up to 225µV/K around 773K), electrical resistivity(5x10-5Ohm M around 933K), and relatively low thermal conductivity(6W/mK around 950K). The lattice thermal conductivity, K[2] was calculated from the Wiedemann-Franz relationship.

Jan 1, 2002

By Winfried Rosenstock

Following successful trials at Chuquicamata / Chile from February to May 2000 and from February 2001 onwards at Burton Coal Mine, RAG International/Thiess Pty Ltd., Queensland / Australia a significant advancement in blasting technology was achieved using electronic detonators. The mine now uses electronic intiation for the majority of overburden blasting.

Jan 1, 2002

By Salama

In the conventional approach, the separator feed incremental masses are assumed to be concentrated at the midpoints of the density or size intervals and subjected to a model partition function. The resulting separation predictions would change if the locations of the incremental masses were changed. As a result. the predicted results depend on the choice of locations where the feed incremental masses are concentrated in the density or size intervals. A technique that utilizes the cumulative-mass-distribution of the circuit feed and the derivative of the partition (separation) function relative to density or size variables is proposed. The proposed technique eliminates the dependency of the predictions on choice of where the feed incremental masses are concentrated within the density or size intervals. Since the proposed technique is based on the cumulative masses at the upper limits of the density or size intervals, the technique produces a single prediction whereas the existing techniques produce predictions that depend on where the incremental masses are concentrated. In fact, it has been demonstrated that the existing conventional technique, in which the incremental masses are concentrated at the midpoints of the density or size intervals, is a first-order approximation of the technique proposed.

Jan 1, 2002

By T. Stuczynski

In the past ten years about 3000 wastewater treatment plants have been built in Poland. The result of this development has been a massive increase in overall sludge production. According to data supplied by the Ministry of Environmental Protection, 400,000 dry tons of sludge are generated every year in Poland (Koblak-Kalinska 1996). Still it is difficult to estimate the amount of sludge, which is used in agriculture or for reclamation purposes. However, it can be assumed that this comes to no more than 10 percent of all sludge produced in Poland on a yearly basis. Thus it became obvious that an urgent solution to this problem was needed. Local authorities in Silesia realized in the early 90?s that a demonstration was necessary to encourage the proper utilization of sludge. This was the basis for establishing the Biosolids Subpart of the Silesia Project, which addressed the use of biosolids in the reclamation of mining and smelting dumps (Stuczynski et al. 1996). Metal waste sites themselves are known to contain more than 87 million tons of waste (Pistelok et al. 1995). Each year this amount increases by approximately 400,000 tons. We realized that a simple solution for stabilizing these sites would be to cover them with vegetation in order to reduce leaching of toxic elements, as well as to keep metallic fugitive dust from entering the environment. The reclamation of smelter waste sites, which was carried out within the framework of the Silesia Project was a joint effort of local government, industry and international research institutions/agencies, including the US Environmental Protection Agency (EPA), the Center for Research and Control of the Environment (OBIKS), Virginia Polytechnic Institute and IUNG. One of the goals was to evaluate the possibility of adapting the rules of sludge management currently used in the United States to conditions commonly found here in industrial regions of Poland. However, the main objective of the Silesia Project was the development of guidelines concerning all aspects of sludge use for the reclamation of degraded lands and waste sites. Biological aspects related to reclamation of metal waste with the use of biosolids will be discussed in this paper.

Jan 1, 2002

By D. P. Nicholson

The current phase of office development at Canary Wharf in the London Docklands includes twelve multi-storey buildings varying from eighteen to forty stories in height. The area of Canary Wharf South comprises five multi-storey buildings with low level in fill podium and garden areas. Three of these multi-storey buildings have "pile-cap" designs where the entire building load is applied to the piles. The remaining two buildings have "piled-raft" designs where allowance is made in the design for part of the building load to be transferred to the raft formation. Using a piled-raft design approach has enabled savings to be made on the number of piles used below the raft. This paper describes the calibration analysis undertaken to validate the design method. The ground conditions at the Canary Wharf site are typically fill and recent gravel deposits over the overconsolidated clay and sand of the Lambeth Group. Below these strata is the Thanet Sand. The Lambeth Group provided the founding layer for the raft and contributed to the pile shaft resistance. The Thanet Sand stratum provided the bearing layer for the 1.5m diameter base grouted bored piles. The piled-raft design required an assessment of the building load transfer through the raft to the formation layer. This load transfer led to significant increases in effective stress in the soil below the raft and thence a corresponding increased the capacity of the piles. This interaction of the raft with the prepared formation contributed to between 27% and 45% increase in total vertical load carrying capacity of the piled-raft substructure compared with the pile-cap design method. The development of the piled-raft design was carried out in three main phases: ? Development of the approach and validation analyses. ? Design work on various schemes resulting in detailed design packages. ? Validation analyses using full 3D finite element analysis (presented herein). The validation of the piled-raft design approach was initially carried out against published case histories for piled-raft interaction. To improve on the validation work a full 3D finite element analysis of a simplified pile raft and superstructure (which contributes stiffness to the raft) was undertaken; the analysis included only a quarter of the structure due to assumed symmetry of the structure and vertical loading. This 3D validation analysis is presented herein. The analysis was carried out using the Oasys LS-DYNA finite element program. Prior to carrying out the analysis of the piled-raft an initial finite element analysis was carried out to back analyse a fully instrumented field pile test providing accurate modelling of a single pile performance. This back analysis allowed confidence in the soil parameters used in the 3D model; comparisons of shaft and base resistances between the pile test and the FE model calculations for the single pile are presented. The parameters provided in this work were then carried into the full 3D model of the piled-raft. The 3D model of the piled-raft structure included 18 piles (12 full piles and 6 half piles on an axis of symmetry of the model).

Jan 1, 2002

By Barun Gorain, Andy Stradling

"The traditional metallurgical scale-up techniques for flotation plants are based on lumped flotation rate constants, dimensionless hydrodynamic numbers and the use of safety factors. Once the plant has been designed, the flotation principles that govern scale-up play almost no role in the optimisation of the circuit to meet its metallurgical targets. This deficiency can potentially lead to a plant design incapable of meeting its targets, especially when circuits incorporate large flotation cells. This paper demonstrates the application of the k = PSbRf model in providing a suitable framework for flotation modelling, scale-up and circuit optimisation, thus presenting an integrated approach to the problem. Studies were conducted at Teck Cominco’s Red Dog concentrator to characterise cell hydrodynamics, gas dispersion properties, fioth flow behaviour, entrainment and ore floatability to obtain the key data necessary to develop a model for the flotation circuit. The findings of these studies are presented in this paper, which provide valuable insights into the modelling and optimisation of the Red Dog flotation circuit.INTRODUCTIONThe traditional methodology for flotation scale-up and plant design is based on the rule-of-thumb with safety factors, dimensionless hydrodynamic group similitude considerations, etc. With the recent trend towards larger flotation cells with volumes of 150 m3 and greater in concentrators, the problem of scale-up has become even more acute. The scale-up factors that may have been tolerated on smaller cells are not applicable to larger cells. The transportation of froth in these large cells adds further complexity to the problem. Arbiter et al. (1980) foresaw this problem and pointed out that if scale-up were attempted by rule-of-thumb and trial-and-error, then the probability of failure would increase with scale. This problem is confounded by the fact that the design and scale-up considerations used for a new flotation circuit play almost no role in optimisation of the circuit to meet its metallurgical target. This results in a plant design incapable of meeting its metallurgical targets. There have been several instances where new concentrators have required significant circuit modifications and additional capacity to achieve design targets."

Jan 1, 2002

By P J. Hawke

Within the Mesa J pisolitic iron ore mine, clay is distributed unevenly throughout the deposit and often forms as pods and channels less than 10 m in width. The mine resource model, based on 50 m + 50 m spaced drilling, has been unable to accurately delineate the clay for scheduling and mining purposes. Therefore, alternative methods for mapping the clay-contaminated ore were sought. Predictive clay mapping will significantly reduce production costs at Mesa J through improved selective mining practices, more accurate scheduling, reduced wear on mining equipment and minimising the need for maintenance of haul roads and ramps. High lateral resolution electromagnetic (EM) surveying using a Geonics EM31 instrument can quickly and inexpensively delineate the extent and orientation of the clays. Preliminary results indicate that a block model based on the interpretation of the EM data can accurately predict the distribution, volume and tonnage of ore and waste material. While rip-line mapping, infill drilling, ground penetrating radar and gravity can delineate clay with various degrees of success, none were as efficient as EM31.

Jan 1, 2002

By Charles Vaught, Kathleen M. Kowalski

Safety and health professionals from all sectors of industry recognize that training is a critical element of an effective safety and health program. A major concern in the mining industry is how to train both an aging workforce and the expected influx of new miners and mine managers as older workers retire. Thus, a review of some of the basic principles of adult learning may be helpful to mine trainers. This paper discusses the principles of adult learning based on research in education and psychology. It stresses the importance of taking a systems approach to training, focusing on the relationship between the environment and technology, and understanding how workers interact with both. The authors argue that the principles of adult learning and a systems approach are fundamental to the delivery of effective training in the mining industry. Examples of training programs developed by the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health are presented within two broad performance domains: routine and nonroutine skills. Basics of curriculum development are also briefly presented to provide the mine trainer with a template for program development.

Jan 1, 2002

By Joseph Bloch

The hydriding of bulk metals and alloys is a gas-solid reaction in which a hydride product layer is initially nucleated adjacent to the gas-solid interface and continues to grow until a complete transformation of the parent (a) phase into the hydride phase. The combination of measurements of the overall hydriding kinetics of samples having defined shapes and dimensions, together with examinations of partially hydrided samples, enables the presentation of the reaction rate in terms of an appropriate reaction model. A common and important type of topochemical development of the hydride in bulk metals and alloys involves a hydride layer formed on the metallic surface. The continuity of the layer can affect the reaction rate. The rate of hydrogen absorption in a sample, in the presence of a hydride layer, is usually analyzed using a model combining several sequential steps in which the hydrogen is transferred from the gas phase into the reaction site. Coupling the flux equations across the layer under proper steady state conditions, results in a complex rate equation in which the steady state rate of hydrogen absorption (proportional to the hydride layer velocity) is expressed in terms of the pressure, temperature, the rate constants of the sequential steps and the critical concentrations of hydrogen in the hydride. Generally, the rate constants of the individual microscopic processes are comparable in magnitude, so that the overall rate is not controlled by any of the specific sequential steps. However, there are two limit cases related to the first stage, the adsorption, for which the general rate equation is much simpler, namely, the fast and the slow adsorption approximations. Using this limit cases, equations are derived for the steady state hydriding rate of a given system. These equations provide means to anticipate the pressure dependence of the steady state absorption rate under low pressures, close to Peq and under very high pressures. At the low pressure regime both the fast and slow absorption cases yield linear pressure dependence. For the very high pressure range, it is found that the rate become independent of the applied pressure. The rate is given then by a combination of the individual rate constants of the system and the critical hydrogen concentrations. The model is shown to apply in several real cases, such as ZrCo, LaNi5 and titanium.

Jan 1, 2002

By Miie Shields, Ed Billington

Trail blasters for the National Park Service (NPS) live and work in remote mountain terrain throughout the western states, where any support or resupply may be sporadic and ditlicult and mountain weather affects every activity. Mechanical “aids” are the pick, shovel, rock-bar, wheelbarrow, and a Pionjar or Cobra dritl. The blaster is usually faced with an extraordinary range of work, t?om delay blasts in weathered rock using driiole depths of 18” (46cm) to as little as 4” (1 Ocm), through reducing boulders and talus fields to useable tread, blasting stumps, snags and log-jams, to the explosive disintegration and casting of animal czcasses. One day he/she might provide a 500cf (14 cu meter) anchor excavation for a suspension bridge, the next day directionally fall 60” (1.5m) diameter snags in a camp area, and the following day blast a 3-foot-wide (1 meter) tread bench across a steep bedrock slope. To be effective, the blaster must design each and every blast around desired end result, crew and public safety, maximizing effective use of limited quantities of explosive, and the minimnation of environmental effects. Since almost all drillhole blasting occurs in the weathered zone of the rock, blasting is more the art than the science of judging rock density, hardness, cohesion and prefracturing, and selecting explosives, drill and delay patterns, and loading techniques responsive to those conditions. For these reasons the NPS issues its own Blaster’s License, with a basic requirement of at least 40 hours of NPS blaster training and 3 years of supervised Blaster in-Training experience. The focus of this pre-license requirement is on safety and using explosives as a precision tool, versus just “blowing things up”.

Jan 1, 2002

By Cameron Rees

The University of New South Wales Mining Research Centre (UMRC) has a longstanding research reputation in mining research, with particular expertise in mining systems, mining geomechanics and excavation engineering. The UMRC is now focusing this expertise on the potential of mining Seafloor Massive Sulphides (SMS). The UMRC has initiated a three-year research project that will identify and examine the requirements to effectively and efficiently mine SMS deposits. The major aims of this project are: ? To develop an understanding of the geomechanical characteristics and local physical environmental conditions associated with a ?typical? SMS deposit. ? To develop and evaluate a range of both conventional and innovative excavation processes for mining SMS deposits, and define the engineering parameters required for each extraction option, and ? To identify the materials handling and lifting requirements of the ?mined? SMS material, and the possible integration of the lifting system with the excavation processes considered.

Jan 1, 2002

By Jacques Villeneuve, Stéphane Brochot, Jean-Claude Guillaneau, Marie-Véronique Durance

Since 1986, BRGM has been developing a powerful process simulation software package, USIM PAC. These last years have seen significant developments in mineral processing technologies, particularly in hydrometallurgy, bio-hydrometallurgy and mineral liberation. The new version of the simulator, USIM PAC 3.0, incorporates these modem-processing fields. Its structure and tools allow the user to take into account, at the same time, a wide range of technological, economical and environmental aspects. The improvement of the existing features and the introduction of new unit operation mathematical models and tools such as the supervisor, global optimization, workshop model or chemical reactions contribute to a global approach in mineral processing design.

Jan 1, 2002

By Johann van Wjk

Mandatory Codes of Practice to Combat Rock Fall Accidents came into force on South African Collieries in 1997. These were drawn up in accordance with guidelines issued by the Chief Inspector of Mines, The Codes of Practice (CoP's) are legal documents in terms of the South African Mine Health and Safety Act 1996. One of the main results Of the introduction of the COP'S from a practitioner's point of view is that they formalized much of what would have constituted a typical visit to an underground section previously. Other important requirements were as Billows: Support rules and Strata Control Standard Procedures were to be drawn tip. Identification of Special Areas (areas requiring a higher level of rock engineering input and with, typically, higher order of support and restrictions on mining geometries), Changing conditions underground to he identified timeously. Implementation of the CoP to he monitored. To comply with these requirements on Ingwe Collieries (a division of BHPO Billiton Energy Coal) it was decided to produce too separate forms to be used in conjunction with each other. The first of these, the "Underground Section Physical Risk Rating" measures the physical conditions in each section whereas the second form, the "Section Perfomance Rating" determines how well the section personnel are Coping with the conditions. This form also pleasures compliance with the Support Rules and Strata Control Standards. Both forms are essentially risk matrices but with various scenarios described, each with a certain weighting. The "Risk and Performance Form" system for bord and pillar operations has by now been used for five years in the Ingwe and Eyesizwe Mining Collieries and has achieved a great deal of acceptance. This system has enabled the quantification of previously subjective observations and has improved the strata control awareness and management of underground mining sections. Amongst other initiatives it has assisted ill reducing the severity and frequency of fall of-ground accidents.

Jan 1, 2002

By B. K. Mishra, R. K. Rajamani, A. D. Joshi

The liners are the most important part in the SAG mill operation. Hence, the liners and their design parameters are primarily studied to see its effect on SAG mill operations. Effective liner designs are directed to reduce downtimes, which is needed for the replacement of worn liners. There exists constant chance of improvement in the capacity of mill by studying the effect of liner design on the charge motion inside the mill. This need is satisfied by three-dimensional discrete element code "Millsoft", which uses Discrete Element Method (DEM) to analyze the motion of charge. This simulation of SAG mill keeps track of all the moving bodies like ball and rock and observes its interaction with liners and lifters. The recent work done on this software helps generating mill to more reality by putting conical wall at feed and discharge end, over the earlier flat walls. Millsoft is an effective tool to watch the change in the motion of the charge due to different types of lifter bars and different design parameters. It was concluded that by simply increasing chord length between the lifters and increasing the face angle of the lifters, capacity of the mill could be increased. On the other hand, this software can also be used to get power draft at the respective mill design.

Jan 1, 2002

By Saba Mohan

This study presents results based on the Pile Installation Demonstration Project (PIDP) that was conducted as a part of the East Span San Francisco-Oakland Bay Bridge Seismic Safety Project. For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was estimated and compared with results of other methods currently available in the literature for predicting the soil pile set-up rate.

Jan 1, 2002

By G C. Kiel, G J. Nicholson

Corporate governance has never been more topical. A glance at any major newspaper or business publication will reveal a litany of corporate failures based upon the governance of the organisations involved (eg Byrne, 2002; Hayes, 2002; The Economist, 2002). The increased compliance requirements and speculative nature of our industry means that corporate governance systems are, if anything, more important than in the general business community (Arthur, 2001). Rather than focus exclusively on the contribution of governance to corporate failure within the mining industry, however, our objective in this paper is to examine how boards can add value to the corporations that they govern. In order to highlight how a board can add value to a company, we commence by outlining the role of the board in the modern corporation in general and the mining industry in particular. We then introduce the concept of shareholder value and identify the steps on which a board needs to focus to enhance shareholder value through value tracking processes. Our discussion pays particular attention to the importance of organisational culture to the companyÆs activities and utilises three case studies from the mining industry. We conclude with an overview of what mining boards can do to enhance their culture and drive performance changes for the benefit of the companies they govern.

Jan 1, 2002

By D. Cronan

Both the S.W. Pacific and Caribbean island arcs are host to submarine hydrothermal mineral deposits, the former more so than the latter. In the S.W. Pacific, the whole gamut of such deposits occurs on the sea floor, sulphides, silicates, Fe and Mn oxides, whereas during the limited studies to date in the Caribbean only hydrothermal Mn oxides have been found to occur on the sea floor there in any abundance. Comparisons between the respective Mn oxides are thus the most fruitful at the present limited stage of our knowledge of Caribbean submarine hydrothermalism. Southwest Pacific hydrothermal ferromanganese oxides and their possible relationships to underlying sulphide mineralisation or bedrock anomalies (the geochemical window concept) has been a fruitful field of research in recent years. Certain element enrichments in crusts may be indicative of underlying mineralisation (Rogers et al. 2001). However, more recent studies on buried hydrothermal crusts in the S.W. Pacific (Cronan et al. 2002) have shown there to have been postdepositional diagenetic uptake of elements in them, and thus these elements cannot be used with any confidence in geochemical exploration for buried sulphide deposits unless sediment involvement can be eliminated.

Jan 1, 2002

By Thomas R. Larson

"Many concentrators use re-circulating “plant” water for dilution in their flotation circuits. However, if crusher dust suppressants, ball mill grinding aids, or even agitator bearing grease are introduced into this water, and the water itself is not subject to cleaning steps, then sufficient quantities of these chemicals may appear in the flotation cells and begin to impact the flotation separation. A bench flotation procedure has been coupled with statistical analysis in order to estimate the impact of small quantities of non-flotation chemicals on flotation performance.INTRODUCTIONCleveland Cliffs produces iron oxide pellets for blast furnace feed, and is developing the capability to produce ferrous metallic products to supply a wider customer base. Cliffs manages five North American iron mines, including the Wabush mine sites in Labrador and Quebec. Based on various characteristics of the ore bodies, the flow sheets of the five mines are diverse. For example, Hibbing Taconite uses magnetic separation alone as their primary upgrading method, but Northshore and Empire use magnetic separation followed by flotation, and Tilden uses flotation alone. Last but not least, the Wabush concentrator upgrades primarily with gravity and electrostatic separation techniques.At Northshore, concentrate from the magnetic separator circuit is fed to a reverse flotation circuit. By design, the magnetic separators operate at the highest possible recovery of magnetite, as the separator tails are discarded, and relatively high silica content was acceptable to Northshore’s customers. As the steel-making industry moved toward lower and lower slag volumes, the silica content in the magnetic separator concentrate became a problem. The flotation step was added in the late 1980s in order to decrease the silica assay of the magnetic separator concentrate to meet the current customer requirements. In this setting, the flotation feed stream contains very little silica that occurs as liberated quartz particles. As the degree of liberation of the flotation feed stream is then a limiting factor for silica removal, the online grind control then was linked to flotation in the overall plant control system so that grind can be adjusted to achieve improved liberation if necessary for the flotation process."

Jan 1, 2002

By Douglas Rudenko

When blasting complaints come, as an industry we often immediately look to the ground vibration as the source of the trouble. Often times we overlook or place less emphasis on the collected air overpressure data. Air blast like ground vibration is an undesirable side effect of blasting and can produce considerable structural response.

Jan 1, 2002