Search Documents

By I. Benning

Since the dismal performance of the Rand Mines management was called to account by its shareholders in 1994, the waves of change have continued to ripple across the South African mining industry .The number of listings on the gold board of the Johannesburg Stock Exchange, that once numbered 40 or 50-odd, have now dwindled to no more than a handful as unprecedented restructuring has taken place. The redefining of the industry has not been limited to the gold sector, but across the base metal, coal, diamond, platinum and industrial mineral sectors as well. At the same time the Mining Houses began to reconsider their funding strategies. Originally established in the early part of the century to ensure the long-term sustainability of their group mining operations by providing substantial financial muscle and technical support, the Mining Houses were faced with a rapidly changing political environment, which proved to be a critical catalyst in giving momentum to the change. Furthermore, the significant development costs and increasing risk profile for new projects, coupled with pressure from shareholders demanding respectable returns, opened the door to opportunities for banks to begin providing external debt by the way of project finance. However, the provision of long-term debt to the South African mining industry had generally not been common since mining companies had financed new projects with equity, or with the cash flows from existing operations. Those banks that had the appetite for exposure to the perceived high risks of the mining sector rapidly built up specialist resource banking divisions capable of addressing the increasing demands of the industry. The application of project finance, the principles of which were developed in the 1970s specifically for infrastructure projects and privatization, is now commonly applied in the financing of greenfield and brownfield mining projects. This paper outlines the approach that lending banks would typically adopt when arranging or providing mining project finance, their usual areas of concern and the way in which the finance is structured to mitigate the many inherent risks.

Jan 1, 2000

By Alaina B. Hanlon

Keywords: Undercooling, Convection, Dendrites, Stainless Steel, Levitation Certain Fe-Cr-Ni stainless steel alloys solidify from an undercooled melt by a two-step process in which the metastable ferrite phase forms first followed by the stable austenite phase. Recent experiments have shown that the lifetime of the metastable phase is strongly influenced by flow within the molten sample. The current research will provide insight to why flow affects the metastable phase. This new understanding will lead to the use of convection to control microstructural evolution in spray-forming of stainless steels. Simulations using a commercial computational fluid dynamics package, FIDAP, yield a range of convective flow velocities that cause mechanical damage to the dendrites which is compared to experimental results. If the convective velocities are great enough that the dendrites bend, then low angle boundaries form at the points of collision. These result in high energy sites that could serve as nuclei for the stable phase.

Jan 1, 2005

By George S. Rice

In response to numerous requests for information as to the status of internal-combustion mine locomotives of the Diesel type that use heavy or nonvolatile oil for fuel, with special reference to their safe use in coal mines, the United States Bureau of Mines is issuing this t port. Data were obtained on application of such locomotives to coal mining only in Belgium, France, Germany, and Great Britain. The locomotives are used in coal mining in other countries, as well as in potash, iron, and other kinds of mining, but their chief development has been in coal mining in Germany, France, and Belgium. Recently popular interest in the Diesel type of engine for motive purposes was aroused in this country by the successful application of Diesel engines to railroad locomotives hauling fast transcontinental trains, and, according to published statements, at a low cost of fuel per mile of run.

Jan 1, 1936

By K Pery, J Leahy

Established metallurgical plants operate in a complex environment of interdependent drivers including technology change, operating and maintenance practice, evolving markets, HSEC requirements, statutory and plant requirements, personnel turnover, ore supply, and financial conditions, to name a few. A successful optimisation program should comprehend these factors and drive towards not only lower operating costs, but also higher rates of return for a given level of investment. Optimisation programs have the potential for very high rates of return on capital that Greenfield projects rarely have. This paper presents a robust strategy and methodology for plant optimisation initiatives as well as a case study of how it was implemented at the QNI Yabulu refinery in Queensland, Australia by an integrated team of researchers, engineers and operators. The methodology is premised on the fact that nobody knows the production asset as well as the current operating team. It covers the optimisation process from ideas generation, various stages of selection against the agreed criteria, development, including testwork, funding approval and implementation. It highlights the benefits in the use of integrated teams, the establishment of a sound project basis, and a diligent, phased approach.

Jan 1, 2004

By Albert W. Deurbrouck

The performance characteristics of five hydrocyclone coal washers were evaluated to determine the sharpness and efficiency of separation that might be anticipated in commercial operation. The hydrocyclone overflows contained generally good clean coal products that would require little re-treating to remove misplaced high-gravity material. The underflows, however, contained from 63.6 to 36.7 percent of misplaced low-gravity material, which would require secondary cleaning to provide acceptable clean coal yields.

Jan 1, 1974

By Serge Moalli

The Ashlu Creek Hydro-electric project, located north of Squamish, BC, at the confluence of Ashlu Creek and the Squamish River, comprises a 49 MW run-of-river project and features a 4.08 m diameter, 4.4 km power tunnel and a 128 m deep drop shaft. The Ashlu Creek Hydro-electric project is being developed by Innergex under Ashlu Creek Investments Limited. Site civil works are being completed by Ledcor CMI of Vancouver with tunnel construction by Frontier Kemper Constructors ULC under a lump sum design-build contract. Site works got underway in September 2006 with the construction of the tunnel portal and laydown area. These site works required rock slope stabilization over a 50 m rock slope to secure the laydown area as well as the construction of a tail track muck tipping station and structural wall to facilitate TBM excavation and spoil removal. Starter tunnel construction commenced in early 2007 and TBM tunneling started in the late spring of 2007 and is planned to continue until early 2009. The power tunnel is being excavated using a 1,200 kW Wirth open-type hard rock TBM dressed with 31?17' cutters. The TBM featured two fixed mounted rock bolt drills behind the finger shield: these were removed and replaced with jacklegs to improve access. A probe drill at the end of the main beam is also present. The geology along the 4.4 km power tunnel comprises very strong and generally massive granitic bedrock with rock strength greater than 225 MPa. A unique feature of the project is that no subsurface investigations have been completed for the tunnel however extensive bedrock outcrops are present along the Ashlu Creek valley. A historical quarry exists approximately mid-way along the tunnel alignment that has exposed good quality granitic bedrock. TBM tunneling to date has achieved advance rates of 10?20 m/day with a maximum of 23 m and has encountered all of the anticipated six major fault zones where the installation of various standard high capacity tunnel support was successful to facilitate TBM advance through these sections.

By Donald A. Bruce

"Abstract The Deep Mixing Methods (DMM), in their current forms, have been employed in the United States since 1986, although an earlier version had seen service from 1954. The earlier developments were strongly influenced by practices in the Nordic countries and Japan, while by the late 1980’s several DMM systems had been developed in the U.S. itself. Since then, DMM has continued its evolution, principally via the challenges of a series of large, landmark projects, but also via distinct, significant technological advances. This paper highlights the key points in the history of DMM in the U.S., and provides an overview of the different methods currently in use.In the BeginningIt is a common misconception that the history of applications of the Deep Mixing Methods (DMM) in the United States dates from 1986 when SMW Seiko Inc. — a subsidiary of Japan’s Seiko Kogyo Company — was established in the Bay Area. However, the author believes that Intrusion Prepakt Co.’s patented MIP (Mixed in Place) system had been used, albeit sporadically (about 30 projects are recorded), since 1954 (FHWA 2000, 2001). Ironically, by 1961 this single auger method had been extensively used under license in Japan for excavation support and groundwater control — by the Seiko Kogyo Company. By 1972, the original MIP technique had been succeeded by more advanced Japanese methods, involving multiple augers. Intrusion Prepakt have long since become defunct.The first systematic studies of contemporary Deep Mixing Methods in Japan began in 1967 when the Port and Harbor Research Institute of the Ministry of Transportation began laboratory testing using granular and powdered lime for treating soft marine soils. Fundamental studies continued through the early 1970’s, by which time the development of industrial scale equipment was well advanced, having its first application on a marine trial near Haneda Airport. Coincidentally, laboratory and field research also began in 1967 in Sweden (“Swedish Lime Column Method”) for treating soft clays using unslaked lime. Reportedly the progenitor was a Norwegian, Kjeld Paus, who had made observations on fluid lime columns in the U.S. It would seem that developments in Japan and the Nordic countries proceeded independently until 1975 when the technology leaders from each group (Broms and Boman; and Okumura and Terashi, respectively) presented their — very similar — findings at a conference in Bangalore, India. Limited technical exchanges ensued thereafter.Whereas the Nordic developments continued to focus on the use of dry reagents (cement and lime) and relatively light equipment compatible with operating on and in very soft clays and organics, the Japanese progressed into the use of fluid reagents (cement-based grouts) and heavier equipment for both marine and land-based projects. Thus, by 1986, there were a large number of proprietary (wet and dry) DMM systems in Japan, and a rapidly growing market already by then accounting for over 12,000,000 m3 of ground treatment."

Jan 1, 2014

By P. R. Jones

A computer program was written for the design of a shell and tube type heat exchanger on a price optimum basis. The program was designed to meet the following requirements: (1) Triangular pitch; (2) single or multiple pass; (3) heating or cooling; and (4) no change in phase. Price optimum design was obtained for four standard tube sizes and standard pitch. Pressure drop both inside and outside were computed and the nearest standard shells having at least the required area were listed. With this information, the estimator can select the heat exchanger best suited for the need. The program was made adaptable to various fluids and to various tube sizes and spacing by reading in much of the required data such as physical properties of the fluids, tube data, and standard shell data in tabular form.

Jan 1, 1967

By A D. Campbell, G R. Power

The objective of the draw strategy in a caving mine is to maximise economic return by minimising waste dilution3 and maximising ore recovery4. The draw strategy must also include suitable controls for air blast and mud rush hazards and is highly constrained until continuous cave propagation has been achieved. This paper details a three-year project at the Ernest Henry Mine (EHM), which used cave flow simulation software to develop a draw strategy that increased the mine value by 32 per cent.Dilution and ore loss can be significant in sublevel cave (SLC) operations and result in poor recovery and considerable economic losses. To minimise dilution and ore loss, cellular automata software was used to simulate cave flow over the mine life. The optimisation project required mining footprints for various cut-off grades to be developed. Draw strategies for each mine footprint were then generated using a range of shut-off grades. Economic assessment of each scenario was then conducted to determine the mine footprint and corresponding draw strategy that generated the highest NPV (net present value). The iterative simulation process was improved by developing automated software functions in the flow modelling software to reduce time taken to generate and assess life-of-mine (LOM) draw strategy scenarios.In addition to improving the NPV of the mine, the optimisation project also enabled a decrease in the mine cut-off grade which increased the ore reserve and extended the mine life. Overall, an iterative process of mine planning, cave simulation, economic evaluation and geotechnical analysis was used to significantly increase the economic return of the SLC whilst ensuring caving risks were controlled to an acceptable level.CITATION:Campbell, A D and Power, G R, 2016. Increasing net present value by a third at an operating sublevel cave mine using draw strategy optimisation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 167–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Gregory Poole

With access to the World Wide Web, many resources are readily available for improving claim reports. With a little time spent on line, a more thorough report can be created. Claimants will accept the conclusions of a report more readily when they can view support information on their own computer, particularly when the support information is not just from blasting related web sites. Some suggested resources are discussed including aerial pictures, local tax maps, topographical maps and home repair web sites. This paper provides suggestions for tracking down support information on the web and information on how to properly reference this information. Case studies of several claim investigations are presented. These are some examples of how a little time spent online provided clear and convincing evidence to support the conclusions of the investigation.

Jan 1, 2006

By R. L. Whiting, H. J. Ramey

The basic study from which this paper was prepared was started as the result of the growing need throughout the world for increasing quantities of energy in all forms. Quite obviously, natural forms of energy that are readily available at low development cost are those in greatest demand. The underdeveloped countries — and particularly those having little or no petroleum resources — are the countries in which the most interest is being shown in the newer energy sources. One of the least expensive energy sources is natural geothermal steam.'-* Although this form of energy has been recognized for centuries, it has been only during the past 20 years that serious efforts have been made to harness it. Natural geothermal steam energy in Italy, New Zealand, Mexico, Japan, and California is now being produced through wells to drive turbines and generate electricity. Further, active exploration for natural geothermal steam is being conducted in Hawaii, Fiji, Taiwan, Chile, Russia, Greece, and Katanga. It is surprising to find that most geothermal steam exploration is in the "steam seep" stage. That is, surface studies are made and exploratory wells are drilled in the general area of steam seeps. However, in the larger geothermal steam areas, there have been efforts to apply the most modern geological and reservoir engineering principles in order to define the reservoir parameters, particularly those relating to estimates of reserves and future productivity. This paper is concerned with the development of appropriate equations and techniques to facilitate these estimates. Production of natural steam or hot water presents problems different from those experienced in the production of oil and gas. For example, steam or hot water systems may be essentially single-component systems, while hydrocarbon systems are most frequently multicomponent fluid systems. Heat effects are much larger for water than for hydrocarbon systems; and the natural steam production may or may not be isothermal, while production of petroleum reservoirs is considered normally to be isothermal. Petroleum reservoir engineering principles may be applied to natural steam or hot water reservoirs if the inherent differences in the systems are considered. The basic considerations involved in geothermal steam reservoir engineering are: thermodynamics, physical and thermal properties of water, materials and energy balances, fluid influx, and performance matching and predicting. Thermodynamics Fig. 1 is a pressure-temperature diagram for the liquid-vapor region for pure water, showing the critical point and five other points representing possible initial conditions for a geothermal steam reservoir. To generate a physical appreciation for the mechanics of natural steam production, it is helpful to consider

Jan 1, 1970

By Loren R. Anderson

Traditionally, an evaluation of the safety of slopes has been based on computing a safety factor against failure. In computing the safety factor, the geometry of the slope, the soil parameters and the pore pressures are treated as deterministic quantities even though they are known to be random variables. A pseudo-three-dimensional probabilistic slope stability model has been developed that treats shear strength as a random variable. The model uses the probability of a slope failure as an assessment of slope reliability. The model can accommodate zoned embankments of soil in which the strength is described by the Mohr-Coulomb strength envelope. Autocorrelation functions are used to describe the spatial correlation of the strength parameters, c and tan ø. Model error can also be included in the analysis. The model has been applied to an existing tailings dam and to several hypothetical examples. These examples are presented to illustrate the influence of the choice of the soil strength variability parameters on the probability of failure. The results show that the critical failure surface based on the minimum safety factor is not necessarily the failure surface that will yield the maximum probability of failure. The analysis of the tailings dam shows that variance reduction can be large and that the model error is the dominant source of uncertainty for the embankment analyzed.

Jan 1, 1982

By Bjarne Ekberg

"The most economical way of dewatering mineral concentrates is to reduce the moisture content in the material mechanically using thickeners and filtration avoiding thermal drying whenever possible. In addition to this, the dewatering process should produce low moisture cake, high quality liquid, consume little energy. As a part of the dewatering process The CERAMEC® capillary filter has been proven to meet these requirements in over 150 installations. The filtration is done by using ceramic filter plates with small pore size. The capillary action in the filter medium secures gas free filtration at good vacuum, and due to the small pore size, filtrate is crystal clean and particle free. The energy consumption is minimal. This paper will discuss results from filters installed at Pyhäsalmi Mine Oy in Finland where the technology was has been used since the late eighties. Results from more recent installations like Los Pelambres in Chile and LKAB in Sweden will also be discussed.INTRODUCTIONThe idea of using capillary action to make dewatering more efficient was invented two decades ago. Ten years later whole filter plants utilizing the new method were delivered to mine concentrators for dewatering of mineral concentrates. Further development of ceramic membrane plates made it possible to meet the requirements in iron ore dewatering. In addition to low cake moisture, high capacity and low energy consumption, there are a lot of environmental advantages in using capillary filtration. One of them is clear filtrate.CAPILLARY FILTRATIONA micro-porous filter material behaves like a large number of narrow capillaries forming a network. When a pressure difference ?P is applied over the wetted, hydrophilic pore with the radius r, the force striving to push the water out of the pore will be ?Ppr2. The force striving to hold the water in the pore will be the vector force 2pr? cosa of the surface tension ? and the cosine contact angle a. Equalling those forces and solving the equation for ?P we get"

Jan 1, 2003

By Piyush K. Dutta

This report describes the design, development, manufacture and incorporation of noise control features on a jumbo drill and the results of successful tests of this drill in surface and underground mines. The noise-reducing features developed under this program are applicable to future designs of jumbo mounted drills that can be cost effectively manufactured and have the potential to reduce noise levels at the operator's position from 115-120 dBA to 95 dBA or less without a reduction of currently attainable drilling rates.

Jan 1, 1985

By Xiong Houjin

In the excavation works of some deep foundation pits within the boundaries of Guang­dong Province of China, though some measures, such as steel sheet piles, diaphragm walls, etc. were taken to protect the walls, the construction of the excavation works was often accompanied by damage of buildings and public facilities, surface settelment. sand boil and collapse of piles. When these happened, only chemical grouting could be used as the most efficient measure for rushing to deal with or rescue the emergencies. Besides, the application of chemical grouting protection wall technique also palys a very important role under the geologic conditions of the coastal areas of Guangdong Province, when applied in the mucky oystershell layer wealthy in water and the deep mud layer, it can not only achieve good results, but also reduce the cost significantly. In this paper, we discuss the water-tight and earth retaining functions of chemical grouting protection wall in weak formation, and introduce the applicable ranges of chemical grouting protection wall in the excavation of deep foundation pits. Some technological principles and design considerations of the construction of chemical grouting protection wall are presented. Different types of protection wall are also introduced.

Jan 1, 1991

By T. M. Barczak

A primary objective of the Bureau of Mines geomechanics research program is to develop a better understanding of support behavior and interaction of supports with the strata so that supports can be more closely engineered to the geological conditions in which they are employed. Four longwall shield supports were instrumented with an eight-transducer instrumentation array to measure leg, canopy capsule, and compression lemniscate link forces from which resultant shield loading was determined. The instrumented supports were monitored over a 4-month period, producing over 75 shield cycles of resultant shield loading. Resultant loading is the true measure of support resistance, providing both roof-to-floor and face-to-waste support reactions as well as the location of the reaction on the shield canopy. Observed roof support reactions were analyzed, with particular emphasis on horizontal shield loading, since it is the least understood design parameter. Average, peak, and change in shield loading during the mining cycle are discussed. Correlations among data parameters are examined, as is the distribution of support loading at the headgate and midface. Conclusions are drawn as to the effectiveness of the shield support at this installation. Recommendations are made for further research needs.

Jan 1, 1987

Multilevel-multiseam hardcoal mines on the European continent usually consist of a huge network of underground openings, sometimes more than 200 km long in total, with some longwalls operating down to a depth of 1,500 m. While operating several longwalls simultaneously, these mines are making use of a number of stationary and mobile measurement- and analysis units in their main ventilation passes combined with atmospheric measurements on the surface. This paper provides an overview over the systems and technology used and describes the typical set-up of a measuring net. To detect and monitor underground fires through fire gases measurement and -analysis, a mobile underground testing laboratory collects data locally in the area of the fire. These laboratories have proven to be extremely useful not only during the actual fire fighting but also for the long-term gas measurements in critical mine areas. They have repeatedly detected starting fires and have thus given the mine the opportunity to react early and to avoid larger damage. Therefore several mobile laboratory units have now been installed for long-term testing in a number of German mines and similar units are being used in the Czech Republic and Poland.

Jan 1, 2012

By Donald W. Gentry

This section deals with one of the most fascinating aspects of mining the evaluation of mine investment opportunities. Be-fore proceeding further, it is important to clarify the meaning of some fundamental terms used frequently in the text. 6.0.1.1 Mine Valuation vs. Evaluation The words "valuation" and "evaluation" in a mining context are often used interchangeably. However, for the purposes of this section, a distinction is made between the two terms in accordance with commonly accepted practice. The word valuation in a mining project context has the rather narrow meaning of placing a dollar or other currency value on the worth of the project as a whole. In other words, the value of a mining project refers to a measure of the desirability of ownership of that property. As such, the major item of interest is, "what is the mine worth?," or `what is the value of the mine?" The value of a mining project may actually be determined in the marketplace at any specific point in time, or it may be estimated by one of several methods. The topic of mine valuation is discussed in more detail in Chapter 6.1. The word evaluation in a mining project context connotes the broader meaning of determining the numerical values of all

Jan 1, 2008

By W. R. Crane

Mining of the red iron ores of the Birmingham district, Alabama, has _gone on energetically for the past 50 years and has created a large iron and steel manufacturing center, the only important one in the South. The district produces about 10 per cent of all the iron ore mined in the United States and 80 per cent of the Alabama output is red ore ; moreover 43 of the 419 blast furnaces of the country are in the district tributary to Birmingham and produce 7 per cent of the pig-iron output. The rapid growth of the district has been made possible by investigations that have led to radical changes in furnace practice; studies of methods by which the low-grade, highsilica ores may be treated by concentration 1 will give still greater impetus to development. The· mode of occurrence of the ore has made mining practice comparatively simple, but with the rapid extension of the workings underground and the disturbed condition of the ore bed some distance from the outcrop, conditions tend to become more difficult. Stoping, handling, support, drainage, and ventilation are all affected, sometimes favorably and sometimes adversely, by the extended workings and increased depth of cover. Should beneficiatioil make available the high-silica ores of the lower bench of the Big Seam, mining practice must necessarily be adapted to the new conditions and will be rendered more difficult as the weight of cover increases at long distances from the outcrop. The support of workings will require more attention as the weight of cover increases, and the efficient and economical operation of the mines will depend largely upon improvements in mining and handling the ore.

Jan 1, 1927

By W. T. Bell, M. P. Lebourg

The perforating of multiple tubingless completions, in which two or more strings of 27/8-in. OD casing are installed in the same borehole, presents two basic problems. First, good completion practices require an eficient perforator that leaves no debris to interfere with subsequent completion operations. Second, and of more complicated nature, a system is needed for controlling the direction of fire so that adjacent strings are not damaged. Development of of a 2-in. OD, steel retrievable, shnped-charge gun has solved the first problem. The second was resolved through development of three different devices to provide directional perforating for the two types of completion methods being employed today. These include a mechanical orienting device and two self-orienting radiation devices. Conceivably, the latter methods could be adapted to the directional perforating (of .upper zones) of conventional dual and triple completions without removing production tubing and packers. INTRODUCTION The recent trend to multiple tubingless completions,' wherein two or more strings of 27/8-in. OD casing are installed in the same borehole, has presented two basic perforating problems. The first problem to be overcome was the design of a gun that would result in efficient perforations without causing debris to bridge in these small-diameter casings. The second problem was, of course, to devise a system for controlling the direction of fire such that adjacent strings would not be damaged. The problem of gun debris in slim-casing completions has been well defined in the numerous 27/8-in. single tubingless completions which have been effected during recent years with the expendable-type perforators. Failure of expendable-gun debris to settle out properly, even with good gun break-up, has resulted in bridging inside these small-diameter casings. This, in turn, has interfered with completion and re-conditioning operations. The past two years have clearly shown, in fact, that debris problems are not confined to this small range of casing with most designs of expendable-type guns. A high incidence of bridging has even been reported in 4%-in. OD casing. The perforating of multiple tubingless completions has entailed, therefore, the development of a completely debris-free gun of adequate performance, as well as the necessary devices to provide positive directional perforating in the two completion methods presently being employed. THE GUN —DESIGN CONSIDERATIONS The design of a shaped-charge gun for slim-casing perforating has presented a maze of interrelated prob-lems. Since the primary specification has been leveled at efficient charge performance with complete elimination of gun debris, it has been necessary to develop a retrievable steel-carrier gun of tubular construction to house the charges. The carrier must be retrievable through 2.29-in. API pump-seating nipples which are usually installed in 2 7/8-in. strings. To provide for recovery of the gun from the well, swelling of the carrier on firing must be carefully controlled. Control of swelling automatically means control of explosive weight in the shaped charge which, in turn, influences charge performance. Carrier swelling also depends upon the confinement pressure at the level being perforated, which imposes a hydrostatic pressure-depth limitation. Burr interference on the wall of the carrier, resulting from passage of the jet through the carrier wall, must be eliminated by suitable design. Clearly then, a satisfactory shaped-charge gun design for slim-casing operations represents a fine balance between carrier swelling, hydrostatic pressure, explosive weight and charge performance. Additionally, to lend itself to directional perforating, the gun design must provide a positive locking mechanism for individual charges within the gun carrier. This fixes charge orientation within the carrier and prevents