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By Timothy M. Dyhr, Marie Garrett

The Cannon Mine gold project has been perceived as unique for being developed in an area characterized by orchards and suburban residences. The Cannon Mine was permitted and developed successfully in this setting. However, the ability of companies to permit, develop and operate mines in mated areas is becoming more difficult as a result of opposition by residents and increasingly stringent regulation. The challenge to the mining operator in the future on otherwise economically attractive mineral deposits will be the ability to explore and develop these types of projects successfully and cost- effectively

Jan 1, 1987

By M. K. Pathak, A. K. Mukhopadhyay, D. C. Panigrahi

Changes in machinery operating and design parameters often result in unexpected vibrations or changes in the vibration patterns. Vibration in a system is an undesirable element that can cause machinery distress. Potential damage can be prevented by identifying the vibration level that is due to the changed operational parameters. This is necessary for the safe and reliable operation of plant equipment. This paper presents a documented study on vibration events that resulted from alterations in operating and design parameters in a mine ventilation fan and analyzes the causes by defining the sequence of events that led to its performance deficiency. This paper is based on experimental effort to study the vibration behavior of a ventilation fan under varying operating conditions.

Jan 1, 1999

By B. Cavender

The operating lifetime, or production rate, selected for a mining project is among the most important factors influencing the project's design and ultimate economic success. Incorrectly-determined lifetimes can lead to the erroneous rejection of projects as uneconomic as well as the suboptimal exploitation of producing properties. This paper examines the optimal lifetime calculation using traditional discounted cash flow and recently-proposed option pricing techniques. Using each method, the production rate is determined as that rate at which the project's net present value is maximized.

Jan 1, 1993

By R. L. Grayson, Y. J. Wang

An integrated approach to the management of underground coal mine production and cost is presented. A conceptual model for objectively analyzing an underground mine to obtain lower cost and higher productivity from operations is outlined. The model is designed to provide mine managers with a quantitative, decision-assisting methodology that can be used in formulating timely responses to fluctuations in operations. It consists of a productivity fore- cast component, routine use of current resource consumption factors, a linear programming scheduling component, a manpower loading analysis, and an inventory control component. The model is applied to an underground coal mine.

Jan 1, 1990

By R. Hogg, E. Kaya

The presence of agglomerated particles in airborne dust in coal mines has been confirmed by SEM examination of static samples collected on substrates. In addition, the effect of agglomerated particles on the performance of cascade impactors and cyclone- type personal samplers has been studied. Simple procedures have been developed for evaluating the extent of agglomeration in air-borne dust by comparing the observed size- selectivity of the sampling devices with that expected under idealized conditions. Applications of these techniques in the laboratory and in underground mines are discussed.

Jan 1, 1992

By Hardy J. Smith

The rock mass parameters which need be evaluated to estimate the rippability of rock are briefly outlined and their significance is discussed. Several methods used for estimating rippability are compared, and the advantages of taking into account a wide spectrum of rock mass parameters are emphasized. A systematic means of numerically weighing six rock mass parameters to produce a Rippability Rating (RR) is recommended, and a method of correlating this rating with the refraction seismograph method and with tractor horsepower is shown. Although the overall method demonstrated is systematic and yields specific numerical results, an integrated approach is recommended to its application, taking into account: the Rippability Rating; seismic velocity and geologic material; and other engineering judgment factors.

Jan 1, 1986

By G. Kazonich, S. L. McGill, J. W. Walkiewicz

Naturally occurring minerals and reagent-grade compounds were tested to determine their receptivity to microwave heating. The maximum temperature achieved for the samples and the time required to reach temperature are reported. A description of the microwave oven and a thermocouple technique that accurately measures and continuously records the temperature of samples during irradiation are reported. Extractive applications using the generated microwave data were investigated. Stress fracturing at mineral grain boundaries in a gangue matrix was shown. This should significantly affect grinding energy requirements and liberation properties. A method to produce a magnetic phase on pyrite surfaces, a method of using microwave heating to retort cinnabar concentrate, and a roast-leaching microwave treatment of chalcopyrite ore are described.

Jan 1, 1987

This section is addressed to the computing needs of corporate (top) management which are less specialized than the computing needs of operating or divisional management described in the previous sections. It is essential that the computer be used as a tool to serve corporate management and that information and results are presented in a succinct form. A key responsibility of the manager of computer applications is to communicate well with corporate management. A common trap for computer management is to allow the development and implementation of sophisticated and academically interesting computer applications which do not enlighten corporate management in its decision-making task. Thus it is essential to devote sufficient time and effort to designing and specifying a computer system before developing and implementing the system.

Jan 1, 1979

By Martin L. Smith

Mine waste characterization and risk assessment currently focesses on water quality and largely ignores boththe charteristics of the wastes themselves and how wastes interact with the environment. Characterization of the parameters that control contamination of pore waters and their migration can quantitatively assess risk and remediation strategies in terms of cost effectiveness and risk reduction. Since mine waste characteristics are spatial, geostatistical methods should be used for characterization and assessment. A number of geostatistical methods are reviewed in terms of their application to mine waste sampling, modeling and risk assessment and management.

Jan 1, 1995

By Tad S. Golosinsk

Use of computers for hoist evaluation and design dates back to the early 1960's. Mine hoist production calculations, repetitive in nature, were computerized first. More elaborate modeling of hoist operations followed soon. Typical for this, early period are the models described by Touwen (1973), and by Albert and McIvor (1984). Apart from the simple hoist production calculations, the models were very complex, typically written in Fortran, and often required advanced computing facilities and expertise to run the simulation. The early models were strictly deterministic, with no consideration given to the random nature of hoisting operations. The effects of randomness of the hoisting process on hoist performance were often accounted for by introduction of the deterministic factors, most notably of an "utilization factor" related to the hoist production. The value of the latter was based on observations of actual hoist performance, and could vary in a wide range. For example Harvey (1973) reports values of the "utilization factor" to be between 0.7 and 0.92.

Jan 1, 1989

By E. D. Goddard, D. S. Murphy

Acid resistance, zeta potential and ESCA (electron spectroscopy. for chemical analysis) experiments were performed on emperador marble and four calcium carbonate samples (onyx calcite, travertine calcite, Iceland spar calcite and aragonite). Six fluorine-containing reagents were used to treat the surfaces of these materials: magnesium hexafluorosilicate, zinc hexafluorosilicate, sodium fluoride, zinc fluoride, strontium fluoride and stannous fluoride. The acid resistance of treated samples proved to be much higher than that of their untreated equivalents. The isoelectric point of treated samples approaches the isoelectric point of fluorite. Also, the fluorine content, as measured by ESCA, of a marble surface treated with magnesium hexafluorosilicate is much higher than that of an untreated sample. The binding energy off of fluorine and calcium the treated marble is consistent with the formation of calcium fluoride.

Jan 1, 1994

By I. Iwasaki, K. A. Smith, X. Cheng

A cathodic decomposition model was examined for both pyrrhotite and chalcopyrite in an attempt to analyze the formation of surface coatings in deoxygenated solutions at natural, near neutral pH. Combination potentials established between the mineral-grinding media pair were simulated by applying a potential of -0.455 V (vs. a standard hydrogen electrode) either to a pyrrhotite or to a chalcopyrite electrode. Chronoamperometry was used to study the polarization behaviors and alteration of mineral surfaces through cathodic processes. The kinetic parameters of cathodic decomposition of pyrrhotite and chalcopyrite were determined and compared. It was concluded that pyrrhotite decomposed faster than chalcopyrite in near-neutral pH solutions. Both minerals were then covered by a film consist¬ing mainly of iron hydroxides, which adversely affected their flotation.

Jan 1, 1999

By M. Abdel-latif, R. W. Bartlett, P. R. Taylor

A cyclone reactor system for the partial reduction and melting of taconite concentrate fines was designed and operated. A nontransferred arc plasma torch was employed as a heat source. Taconite fines, carbon monoxide and carbon dioxide were fed axially into the reactor, while the plasma gas was introduced tangentially into the cyclone. The average reactor temperature was maintained above 1673 OK (1400°C), and reduction experiments were performed under various conditions. The influence of the following parameters on the reduction of taconite was investigated: carbonmonoxide to carbon dioxide inlet feed ratio, carbon monoxide inlet partial pres- sure and average reactor temperature. The interaction of the graphite lining with carbon dioxide and taconite were also studied.

Jan 1, 1995

By R. L. Kloberdanz

Compania Minera Disputada de las Condes S.A. (Disputada) is proactively implementing closure and reclamation planning activities at its mining and beneficiation facilities (mining facilities) in Chile where regulations governing mine reclamation are not yet fully in place. These activities are being implemented to improve currently employed measures to protect human health and the environment and to enhance reclamation and facilitate future closure with regard to these areas when mining is completed. As part of this process, Disputada, with the assistance of Shepherd Miller, Inc., developed recommendations and guidelines for future closure and reclamation of the Disputada sites. These recommendations and guidance incorporate planning and operational and post-operational design considerations and practices, and standards used by the mining industry and regulatory agencies around the world. The criteria presented in the guidance are based on achieving conditions that will be suitable for the anticipated post-mining land use. This paper discusses the process and approach taken, and the results.

Jan 1, 1999

By Ch. Apostolaki

Eighty samples from Roman wall paintings from ancient Corinth were studied by means of optical and scanning electron microscopy coupled to an energy dispersive analyzer, X-ray diffraction and image analysis techniques. The goals of the study were the identification of the exact nature of the pigments and the technical features of paint application (binding medium, adherence to plaster, thickness of the pigment layer), which would provide evidence about the painting technique (fresco or secco). The main plaster is calcitic with secondary calcite as a cement binder to the primary calcite grains. All pigments, except Egyptian Blue, were naturally occurring ochres or pigment minerals, such as limonite, goethite, hematite for yellow, brown and red hues, cinnabar for red hues and celadonite for green color. The presence of specific elements such as Ni and Cr or minerals such as olivine, in the yellow, brown and red pigments, gave an indication about the provenance of the original pigments, which seems to be from Cyprus. The black color was represented using charcoal. It seems, finally, that for the pigment application the fresco technique was used, while secco is also apparent.

Jan 1, 2006

By W. Petruk

Mineral liberations that would be obtained by grinding an ore to a specific size can be predicted by analyzing unbroken ore pieces, and mineral liberations in ground ores and mill products can be determined directly by image analysis. Predictions of mineral liberations are made by measuring size distributions and textures of mineral grains by image analysis and using liberation models. Ground ores and mill products are analyzed to determine the proportion of mineral that is liberated, and the data are used to evaluate mineral behavior during mineral beneficiation. The liberation data for minerals in a suite of mill products from a circuit are processed by a materials balancing technique to calculate recoveries of minerals in different types of particles throughout the circuit. The liberation-materials balance data define mineral recoveries; define the behavior of an ore in a concentrator, pilot plant or bench test: and indicate whether recovery improvements are possible and/or feasible.

Jan 1, 1992

By Kenneth N. Han, Xinghui Meng, A. J. Monhemius, G. W. Warren, E. Peters

The leaching of gold in ammoniacal solutions containing various oxidants in an autoclave has been investigated. Also studied are thermodynamic and kinetic aspects of the ammonia leaching of gold and silver. The variables studied included stirring speed, temperature, concentration of ammonia, ammonium, and various anions. Arrhenius activation energy values were found to be between 47.1 kJ/mol and 86.2 kJ/mol depending upon the kinds of oxidants used. An electrochemical reaction controlling mechanism has been proposed for the dissolution reaction. The leaching behavior of gold and silver from various ores in ammoniacal solutions containing various oxidants has also been investigated. The samples tested included sulfidic as well as carbonaceous refractory ores. The recoveries of gold and silver from these refractory ores were better than 96% within 2-3 hours of leaching time.

Jan 1, 1993

By Andrzej Frycz

The development of the theory of reliability creates more and more possibilities of its application in different domains of technics. The methods evolved to date, both theoretical analysis of the engineering systems and investigations techniques in practice can be put in use a d translated from one science to another one [1,3,7J . It needs to consider the specific of the different sciences. But it is necessary to take account of the specific characteristic of each line of science. The reliability investigations needs, justified in technical and economical viewpoint appear too in mine ventilation technics and systems. The mine ventilation system is a complex of workings and ventilation plants, which serve to supply the networks with a sufficient quantity of fresh air from the atmosphere and then carry off the vitiated air. The condition necessary for a ventilation system to perform definite task is the correctness of all its elements, that is a capability to preserve in a expected range of tolerance, the values of basic parameters. The element of a system which ceases to work correctly is called failed. The basic parameter of all elements of a ventilation system is the characteristic curve, pressure loss - air quantity relation ?p = f(Q) (1) This curve concerning the workings and ventilation stoppings is given by the formula: ?p = R Q2 (2) thus the resistance R (of the workings or stoppings) may be taken as a characteristic parameter. The course of this characteristic f(Q) will be given in a complex form in concern with fans, ejectors, air curtains. The failure of a ventilation plant or working is therefore an event, relying on a change of its characteristic, thus for a definite time the losses of the plant's or working's capability set in for the fulfilment of its function in the ventilation system. The failures are divided in viewpoint of their nature on sudden and progressive. We are in concern with the sudden failures which are characterised by a violent change of the ventilation element parameter for example a fall of roof, or silt up of the working, opening or failure of the ventilation stopping, the stand-off of the fan or ejector etc. We distinguish two kinds of failures on the viewpoint of their action on the air flow: the "opening" failure and "closure" failure. The prevalence of factors, which causes the failures is in connection with the intersection in the mine of roads of haulage, roads of underground transport of materials and lining elements, roads of people motion with airways, as also depends on the rock pressure reaction on the workings lining and plants placed there. Other factors will yet be decisive upon supply decay of fans, ejectors and curtains. The appearance of failure of the ventilation element is therefore of random nature and determines the change of the element, when it is passing from operating state to unoperate. Qualifying the ventilation system element to one of these states is easy, when the characteristic change is clear and occurs suddenly, that was assumed. The investigations conducted by Patrushev and Karnaukh [91 in concern with the ventilation stoppings resistance change in the case of their opening, had shown the possibility of resistance value change in the range of several hundreds higher.

Jan 1, 1980

By Peter J. Huck, Swpan Bhattacharya, Madan M. Singh

This paper reviews the state-of -the-art techniques for estimating the duration of post- mining subsidence arising from different mining techniques and evaluates existing post-mining liability systems in the United States and abroad. For each mining technique (room-and-pillar and longwall) the mechanism of subsidence development is examined and the critical factors influencing the duration of subsidence are evaluated. These are followed by a comprehensive summary of field data on the duration of subsidence movements collected in various parts of the world. Using this information, graphical charts are developed to depict the relationship between the time duration and critical controlling factors. Also included are any mathematical relationships that may exist between the different variables. Finally, a survey of current state, federal and foreign legislation on mine operator liability time spans is provided. These laws are evaluated for their applicability in light of the data on duration of residual subsidence. On the basis of this evaluation, guidelines are suggested for the establishment of the mine operator liability structure for the United States.

Jan 1, 1986

By Jaril B. Lavrencic

The unique and irregulator distribution of working places in a mine always poses the two questions: - which and how much production equipment is to be used, - what production can be expected. Since the development of analytical methods would be impractical for such cases, a lot of computer programs has emerged in recent years trying to simulate the productiom process and thus find the best answer. The usege of a simulator has its dark side well felt by the author(s) of such a program: the credibility and the confidence of the customer. Using the simulator means to respect and to incorporate all the restrictions imposed by the narow underground space, methods of production, safety regulations etc., which can turn out to become a major programming effort. If the program is not properly structured, it will be used for a single special' case only, and never again. In this paper the structure and internal mechanism of the simulator is described for which the author believes that can easily be adapted to conditions of various underground and open pit mines. MINSIM tries to reach the following rather ambitious goals: 1) Estimation of the production before opening the mine, or a part of the mine. 2) Training the personnel to make decisions. 3) Making the daily time schedules for the entire fleet of the equipment units.

Jan 1, 1989