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By Robert T. McKnight

Introduction The minerals exploration business, like many businesses, is faced with the problem of valuing future, risky cashflows. These cashflows are derived from those mineral deposits which have been successfully commercialized. Many deposits, however, do not have the quantities or grade of ore to be considered economic at the projected metal prices using the traditional tools of the Capital Asset Pricing Model and discounted cashflow analyses. If one calculates the future revenues, costs and cashflows of one these marginal properties, and discounted it at the appropriate risk-adjusted discount rate, it may have a negative present value. Yet such a property may still have real, positive value in the marketplace. Why would a firm pay money for a property with an (apparent) minus present value? Mining properties such as these are bought and sold in arms- length transactions on a regular basis. Why is this so? Part of the reason relates to the nature of ore reserve information. To generate cashflows, the analyst must t assume that the reserve information is known with certainty when, in fact, reserves are not known with certainty. Mineral reserves are a function of commodity price, extraction costs and the level of (usually drilling) information about the reserves. Stated, or currently known, mineral inventories may vastly understate the true state of nature. Some firms may therefore be buying a property based on a completely

Jan 1, 1988

By Gürkan Bacak

Study area is located on the NorthWestern of Yatagan-Yenikoy and placed in the units of the crystaline Menderes massif of Eagen, Turkey. Stratigraphically gneissic, migmatitic and metagranitic rocks are found at the base. Garnet schists, phyllitic rocks lie unconfirmitelly upon the basement rocks. Permian aged marbles can be observed as diferrent sized lenses within the schists. Triassic, Jurassic and Cretaceous aged gray colored dolomites and pure crystaline calcite bearing marbles lie upon the Permian aged schists. Neogen series, mainly composed of conglomerates, claystones, marl and limestones unconformly cover the other basement series, mentioned above. Pure calcite bearing marble occurances are found at 2 locations in the study area. These are known as Berber Quarry and Kavuk Quarry. Samples numbered as N7, N8, NA from the Berber Quarry, mineralogically composed of Calcite (97-99%)+iron oxide (1-3%) and chemically contain CaCO3 (97,98%), Fe2O3 (0.5-1%), SiO2 (0.025%) N9 and N10, sampled from the Kavuk Quarry-mineralogically composed of Calcite (94,95%)+iron oxide (2-3%)+albite-Quartz (1-2%) and chemically contain CaCO3 (92-93%), SiO2 1.49%, Fe2O3 0.42%. Especially in plastic and paint sector albite and quartz are unwilling minerals due to their hardness. Approximatelly 1/20 of the study area (87.500 km2) contains industrial calcite occurances. Moreover about 100 billion Tons geological, 1.86 billion tons runable (possible) calcite reserve calculated. It can be expected the calcite quality will be increased with depth. During the running stage of the quarries over burden removel and hand sorting processes will positive affect of the quality.

Jan 1, 2005

By David F. Gibson

This paper presents an outline of several models that have been developed to aid surface mine planners evaluate alternative mining methods and dragline sizes. The models presented belong to a larger group of models that are incorporated in the SEAMPLAN computerized mine and reclamation planning system. SEAMPLAN was developed in the College of Engineering at Montana State University. Initial funding for the development was derived from the USDA Forest Ser- vice and EPA. Enhancements to SEAMPLAN are currently being funded by DOE (Contract DE-AC22-80ET-14173). SEAMPLAN is a comprehensive surface mine and reclamation planning tool that contains a number of major modules: Data Entry and Review, Production Analysis, Reclamation Analysis, and Impact Analysis. The Production Analysis Module contains programs that enable the user to evaluate alternative methods of removing overburden in a surface coal mine and then to assess auxiliary activities required to support the overburden removal operation. A set of these programs addresses the use of draglines for removing overburden. Six basic dragline mining techniques have been modeled. For one-pass dragline operations four methods can be analyzed: (i) simple side cast, (ii) side bench, (iii) extended bench, and (iv) extended bench with side bench. Two methods of two-pass operations are modeled: (i) single dragline, and (ii) tandem draglines.

Jan 1, 1982

By Sidney L. Hansen

This report was written because of concerns of the possible error involved when stopping leakage is incorrectly assumed to be turbulent. It is common practice to use turbulent flow to characterize each airway branch for computer models of mine ventilation circuits. This report addresses computer methods to accurately model air-leakage paths. A graphical method is described for deriving the equations of leakage through stoppings. The significance of modeling leakage according to the proper flow regime (turbulent or laminar) is demonstrated by the following method. A hypothetical mine was developed to represent present-day conditions. The stoppings of the mine were chosen to leak according to laminar flow properties. The mine was represented by constructing two base models. One base model used turbulent leakage equations for each stopping, while allowing the corresponding resistances to vary. The other base model used the correct laminar leakage equations and held corresponding resistances constant. The mine circuit was then expanded to demonstrate future development. The expanded portion was designed with stoppings that were identical to those in the base mine. The mine in the future state was represented by two projection models. Each projection model was an extended version of its associated base model; one used turbulent leakage equations and one used laminar leakage equations for stoppings. The laminar projection was theoretically correct and is used as a basis for comparison of differences in airflow quantities. Rather than modeling every leakage path for stoppings, a more practical approach is also discussed. A good level of accuracy is maintained by combining leakage paths if the proper flow equations are used. This method was used on the hypothetical mine projection and the flows were very similar to the theoretical values.

Jan 1, 1989

By John W. Kelse

What happens when the skull and crossbones goes on a product? In the case of cancer warnings, the consequences can be severe. If the label contains the term "lung carcinogen", you might expect to compensate a lot of smokers, meet a lot of expensive lawyers, be counseled by equally expensive consultants and pay sharply elevated insurance premiums, if you are able to obtain coverage at all. At the extreme, you may face plant shutdowns, job losses or even Chapter 11 bankruptcy. Regardless of how you fare, you are likely to learn some very disconcerting things about the risk evaluation and regulatory system which required you to label in the first place. If a particular material or product does pose a health risk, you are obliged both legally and morally to warn those potentially exposed. Once that warning appears on the label, however, the consequences are often beyond your control. You and your embattled product become part of a legal/regulatory system which has a life of its own. Therefore, the issue of health labeling is not so much whether one warns but rather whether the warning itself is justified and the reasonableness of what happens afterwards. It is this matter of justification and reasonableness, particularly of cancer warnings, which this paper addresses. Until, as they say, your ox has been gored, we tend to believe that risk is determined by the best available technology and expertise We expect that risk evaluators appreciate the ramifications of their work and place things in proper perspective; that risk has been appropriately demonstrated before it is publicized and regulated; that the time-honored concept of prudence, to err on the side of safety, has not been excessively stretched. Unfortunately, the risk evaluation process is rarely, if ever, this

Jan 1, 1991

By G. Falalakis

The Perama Hill gold project is an environmentally friendly project designed with the principle of zero discharge to the environment. The main issues of the proposed mine that are addressed in this paper are the water management, the dam and tailings management facility parameters as well as the mine closure plan, which demonstrate the sustainable design of the project. The water plant circuit will operate using 87% of recycled water and rainfalls, while the pumped aquifer is completely unsuitable for any other use. The proposed water management plan is based on different meteorological conditions for every month and optimizes the external water needs. The tailings pond area that is sited on intensely argilized rocks, will be composite-lined resulting in a permeability value of less than 10-10 m/s, and will exceed the safety parameters for maximum earthquake intensity, flood conditions and seepage. Tailings will contain less than 1 ppm cyanides (almost potable water ranges) and will be free of heavy metals (oxide ore material). The proposed rehabilitation plan comprises of decommissioning and demolition of the plant and auxiliary facilities, open pit partial back-filling and recontouring, appropriate capping of the tailings impoundment, revegetation, maintenance of area drainage system and monitoring for 5 years after rehabilitation. The plan is fullycosted, will be prepaid and through the agreed final land uses with the local community and the proposed actions of the corporate responsibility will attribute to the sustainable development of the area. The design of the Perama Hill project according to new EU and UN legislation and practices ensures that it will be the best example of gold mining operations in Greece.

Jan 1, 2008

By Kim A. Lapakko, William W. III White

The ASTM standard method D 5744-96 was developed to provide a well-defined kinetic test protocol, conducted under controlled reaction conditions, with the intent of generating reproducible results. A preliminary indication of the repeatability of a simplified alternative method (MN DNR method) was assessed and results from the MN DNR method were compared to those from the ASTM method. To provide an indication of repeatability, six samples from three different rock types were subjected to dissolution testing for periods of 20 to 68 weeks. Drainage pH values at the end of the tests were within 0.5 units in all cases and within 0.05 units in four cases. The percent difference from the mean for overall sulfate rates from paired cells ranged from 0.04 to 1756, with a median of 6.3%. Nine samples from four rock types were subjected to both MN DNR and ASTM tests for periods of 20 to 132 weeks. The difference in final drainage pH values forsix of the samples was less than 0.1 unit, and these values were less than pH 3.65 or greater than pH 8.0. The final drainage pH difference for the last three samples ranged from 0.15 to 0.4, and these values were ill the pH range of 6.2 to 7.2. The sulfate release rates for the periods of record for the MN DNR method were 70 to 150% of those for the ASTM method, with a median value of 110%. Sulfate and calcium release from the two methods was not substantially different. The MN DNR method typically produced higher magnesium release.

Jan 1, 2000

By Mark A. Anderson

INTRODUCTION The accomplishment of a well engineered design, and the realization of efficient plant operation cannot be achieved without weaving a web of safety consciousness from the beginning of the project. When the plant becomes operational, and throughout its life, responsibility safety will rest with the client or operator. Recognition of this understanding does not reduce the importance of the engineering and construction contractor's role, but merely puts the responsibility where it belongs. A project which has had little or no operator input during the early stages of design is almost certain to have serious work place safety, health, and environmental problems in spite of the fact that all MSHA and OSHA design requirements were met and the engineering was performed using accepted practices. DEFINITIONS The author has a personal preference in safety definitions that begins and ends with simplicity. If the safety criteria, program, and rules are confusing or complex, the results will soon become obvious. Confusing and complex are the key elements in the avoidance of responsibility and if punitive is added to the list, a brew exists which breeds accidents, illness, and poor performance. A safely designed and operated plant is one that a worker can journey to each day; leaving that person and his or her family with the above average expectation that the person will return healthy, emotionally intact, and hopefully a little wealthier. If the objective or results of a planned or existing safety program don't fit the definition. then the reader is probably contemplating a very sophisticated

Jan 1, 1986

By Judith A. Marks, Deane K. Smith, Jan M. Mutmansky, Maria Klimkiewicz

The mechanical mining of coal seams where roof, partings, and floor rock are extracted along with the coal often introduces large numbers of quartz particles into the mine atmosphere. This study concentrates on the quartz properties in situ and in the airborne dust to determine how they are released from the source rock and whether they are fractured by the mining machinery. Three mines using drum-type continuous miners from different geographic areas were sampled to provide a data base. The roof and floor rocks were primarily siltstones containing 5% to 25% quartz measured by the X-ray powder diffraction (XRPD) method. Much of the work presented here is based on the morphologies of the mineral grains determined by the scanning electron microscope (SEM). The study concentrated on particles of 0.2 to 10.0 µm and on particles containing > 75% Si. Mechanically-crushed quartz particles were also examined for comparison purposes. Particle shapes from the airborne samples suggested that fractured quartz particles were rare. Particle statistics also show that the average size of quartz particles in the airborne samples were similar to the average size of all particles. The conclusion is that very few quartz particles from the source rocks are fractured during mining due to their small initial size and the protection of the associated clays.

Jan 1, 1991

By R. A. Jankowski

Although the number of operating longwall mining systems has remained relatively constant, longwall production levels during the last five years have increased significantly. In the United States, longwall mining now accounts for approximately 50% of all underground coal production. While longwalls are highly productive and offer other advantages, operations employing this method of mining continue to experience dust-compliance problems. This increased longwall productivity has meant that far more dust is being produced. An improved understanding of the longwall face-ventilation system and the advancement of face-ventilation technologies are necessary to ensure all face personnel are allowed to work in an environment that is free of excessive levels of airborne respirable coal mine dust. The Dust and Toxic Substances Control Branch, National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, examined several basic principles of the long wall face-ventilation system and has evaluated the effectiveness of numerous improved face-ventilation techniques for longwall mining systems. These include identifying improved techniques for measuring face-ventilation parameters on longwall mining sections and investigating the fundamental relationship between face airflow and the entrainment and dilution of respirable coal mine dust. Studies have been completed to determine the impact on face dust levels of using belt entry air to ventilate the longwall. Novel methods have been identified to increase the face air¬flow and to manage face airflow to effectively minimize dust exposure to face workers. Unique systems of auxiliary face ventilation have been developed and evaluated at full-scale, simulated longwall test facilities. The theoretical and applied aspects of each of these principles and technologies are discussed. Application of these results throughout the longwall mining industry, as documented from surveys conducted in the early 1980s and 1990s, have reduced the health hazard associated with excessive exposure to respirable coal mine dust.

Jan 1, 2000

By H. S. Kibler, A. E. J. Gallagher, J. J. Sebesta

A review will be made of the nature, value, costs, and factors associated with industrial minerals production in general. Comparisons will also be made between some of these data and similar criteria for metallic mineral production.

Jan 1, 1987

By Charles Schmidt

Phalabonva (Figure 1) is situated in the northern province of South Africa adjacent to Kruger National Park, about 500 km from Johannesburg. The nearest South African port to Phalaborwa is Richards Bay about 700 km distant by rail.

Jan 1, 1999

By A. Filyk, R. Woods

The current plant practice at Molycorp, Inc., Questa Division, a molybdenum producer in northern New Mexico, is described. An outline of crushing, grinding, flotation, drying, and tailings disposal is included, with emphasis on metallurgy.

Jan 1, 1976

By N. I. Jayaraman

Dust scrubbers on continuous miners are steadily gaining in popularity. Recent US Bureau of Mines research on scrubbers is reviewed, with emphasis on development of a new type of water-powered scrubber that can he retrofitted to existing miners; comparison of scrubber effectiveness with blowing and exhaust line ventilation; and improving the quartz dust collection of flooded-bed panels.

Jan 1, 1990

By Q. X. Yun, S. H. Liu

This paper provides a new approach to determine the opening layout in underground mining methods by means of genetic programming. Based on a set of random combination of openings, the layout of openings will gradually improve with the help of genetic operations, including reproduction, crossover, mutation and fitness calculation. The optimal solution will finally emerge according to Darwinian principle: "the survival of the fittest ".

Jan 1, 2002

By Paul G. Greenhill

The Australian Mineral Industries Research Association (AMIRA) was established by the Australian mineral industry in 1959 to develop and manage collaboratively funded research projects. Owned and managed by industry, it coordinates research that answers questions defined by the sponsoring companies of the projects. Now over 35 years old, the Association is an excellent example of what can be achieved through collaborative research and an industry - backed research organisation.

Jan 1, 2000

By Dennis Ofiara, Paul Zick

Two 8.2 m diameter flood control tunnels are being constructed in the Taylor Shale Formation beneath San Antonio, Texas. These tunnels use precast concrete segments as final lining. This paper describes the features of the segments chosen for this project. The tunnels are being excavated with a hybrid Tunnel Boring Machine. This paper also describes the features of the TBM which make the machine compatible to the type of segments chosen.

Jan 1, 1989

By Richard R. Klimpel

This paper summarizes the author's laboratory and industrial experiences in designing and evaluating frothers for optimal coal flotation circuit performance. The key variables discussed are particle size distribution hydrocarbon addition rate, frother chemical structure, and frother dosage. A number of detailed examples will be used to illustrate the important rare/recovery/selectivity interactions that can occur.

Jan 1, 1995

By J. A. Herbst, L. B. Hales, R. A. Ynchausti

Industrial application, theoretical discussion and technical research programs continue to stimulate acceptance of column flotation. Numerous authors have published model, parameter and application studies discussing advantages and problems which are associated with this minerals processing technique. This paper dispells the myth of the self-controlling column while focusing on the problems and opportunities which are inherent in the computer control of a column flotation cell.

Jan 1, 1988

By John K. Kellis, Fazley Azhar

Advancements in AC drive technology offer conveyor designers a viable drive alternative for conveyor systems which require accurate load sharing as well as multiple drive systems. Recently developed AC drives have the ability to accurately control the output torque of AC motor. These AC drives, compared to current DC drives, offer superior performance characteristics while enjoying the benefits of an AC motor. Conveyor applications and case studies incorporating this AC drive technology are presented for review.

Jan 1, 1998