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By M. J. McPherson, P. Mousset-Jones, G. Danko, I. M. Konduri, F. Calizaya

The flow of air through a bare rock, underground airway is affected by the size and frequency of the micro- and macro-asperities of the rough surface. The focus of this study is to characterize this roughness using the coefficient of friction, the friction factor and the fractal dimension. The rough surfaces were identified by two sets of 177 and 78 transverse profiles measured by a laser profiler along the length of an underground airway at the Sunshine Mine, Idaho. Based on the measurements, the friction factor was estimated from Atkinson's equation and the coefficient of friction from the Moody diagram, and power series and variography were used for computing a fractal dimension for the airway surface. Significant conclusions are reached relating the effect of error in the measurement of cross-sectional and rubbing surface areas of a drift, on the estimated friction factor for the airway. The potential role of the fractal dimension as an alternative to the friction factor for characterizing the roughness of a mine airway is discussed.

Jan 1, 1993

By K. Terhaar, K. Prisbrey

The objective was to determine operating protocols for a lead and silver column flotation cleaner being considered for installation at Sunshine Precious Metals Inc. 's Kellogg mill in Northern Idaho. In this column, tetrahedrite and galena were floated, and pyrite and other gangue minerals, including siderite and silica, were depressed. The procedure was to develop a dynamic simulation using a linear transfer function approach. The transfer function related cause-and-effect variables such as the influence of collector and depressant dosages on recovery and grades. Bench-scale flotation tests followed by pilot column testing provided the data used to develop a linear transfer function. The transfer function was derived using a spreadsheet. This model was applied to simulate how the flotation column could be made to respond to disturbances in feed grade. The results were that xanthate, zinc sulfate and sodium cyanide were found to be suitable controls for grade and recovery. Simulations showed the best sequence of manipulations of these reagents, and these sequences are useful for future operator training. The conclusion was that linear transfer functions were able to simulate lead and silver recovery, develop scenarios for operator training and provide a foundation for future on-line control.

Jan 1, 2002

By R. V. Ramani, S. Tan

A computer-oriented systems simulator (CMHS) has been developed for analysis of continuous materials handling systems. Special emphasis has been placed in the model on several features that are unique to these systems. These features include periodic pattern of material arrival from several sources, several types of material to he transferred, material dispatch processes, intermediate storage capacities, and multiple material destinations. Both the deterministic factors of the continuous material handling system, such as the physical decomposition of the system and the scheme and schedule of its operation, and the stochastic factors, such as variations of material arrival, material pattern on the conveyor, and availabilities of the system elements, are considered in the simulator. The application, of the model is demonstrated through a study of an underground conveyor belt network serving long- wall and continuous miner sections.

Jan 1, 1990

By Ruoming Gong, Arindam Samanta, Ragula Bhaskar

Three studies conducted at the University of Utah relating to the effect of scrubbers on face airflow patterns, the resulting dust exposure of operators and the development of a throat scrubber for continuous miners are summarized in this paper. The first study involved full-scale laboratory tests to determine the potential dispersion patterns and transport of dust at a continuous miner face, using different ventilation configurations and a scrubber. Concentration maps were developed and potential exposures at operator positions were examined. The second study involved the development of a 3-D numerical model to predict airflow patterns generated by a scrubber at a continuous miner face. The model was designed to evaluate the role of various face parameters on airflow patterns at a miner face and to complement the full-scale testing. The third study involved the design and fabrication of a low profile hydraulically powered continuous miner throat scrubber. The scrubber uses three hydraulic motors and small diameter fans to draw about 3000 cfm (1.42 m3/s) of air and uses a flooded bed scrubber to filter dust particles.

Jan 1, 1993

By Sol Ribakoff

In 1973, the Subcommittee on Contracting Practices, U. S. National Committee on Tunneling Technology, National Academy of Sciences, under the able chairmanship of A. A. Mathews, Engineering Consultant, now residing at Kaunakokai, Hawaii, undertook the task of developing recommendations for improving the performance of underground construction work, reducing the costs of such work and minimizing the adverse atmosphere in which owners and contractors were performing their respective functions. The author of this paper and C. F. Palmetier, a highly qualified engineer, were thereupon appointed as staff assistants to the Subcommittee, to conduct a study of existing practices and relationships in Western Europe and in the United States, to formulate recommendations, for consideration by the Subcommittee and the participants in a future workshop, as to desirable improvements in United States contracting practices and relationships. The study, conducted during 1973 and 1974, involved personal interviews of a total of 162 owners, engineers, contractors, lawyers, and educators throughout the United States and in 7 European countries, the analysis of 178 replies to questionnaires sent to individuals and firms involved directly or indirectly in construction, and a workshop, near Napa, California, attended by 53 representatives of all segments of the construction community. The resulting report, entitled "Better Contracting for Underground Construction", was submitted by the Subcommittee to the National Academy of Sciences, which approved its publication in 1974 by the National Technical Information Service. It may be obtained from that Service at Springfield, Virginia, 22161, as Accession No. PB-236 973. It was recognized-during the course of the study that while contracting practices and owner-contractor relationships were the

Jan 1, 1981

The US Geological Survey (USGS) held a one-day workshop at its Denver, CO facility to inform the public of the status of its National Mapping Program. In addition, the agency wanted to obtain information from topographic map users on what their needs are. The agency wants to know what the topographic map user wants. The USGS faces the challenge of keeping up with the changing needs of the nation. In the last few years, the agency has changed dramatically to meet these needs. For example, the "new" USGS incorporates mineral-information specialists from the former US Bureau of Mines and also uses the expertise of former National Biological Service employees. These areas complement the agency's traditional strengths in mapping, geology and water re- sources. The stated mission of the USGS's National Mapping Division is to "meet the nation's need for basic geospatial data, ensuring access to and advancing the application of these data and other related ears science information f& users worldwide." To accomplish this goal, the USGS publishes topographic maps, including shaded-relief editions of areas of special interest (state maps and national parks); photo image maps; satellite image maps; geologic maps and hydrologic maps. The geologic maps include geologic quadrangle maps, oil and gas investigation maps and charts, and coal investigations maps. The familiar 7.5-minute series topographic maps are the most widely used. The 7.5-minute- (1:24,000-scale-) format mapping was begun in 1935.

Jan 1, 1998

By Reid Trent, Jon C. Volkwein

The U.S. Bureau of Mines is investigating a novel technique to control methane in underground mines by using methane oxidizing microorganisms termed methanotrophs. Coalbed methane has been responsible for many mine disasters and will continue to be a safety obstacle to mining deeper coal seams. Deeper seams of coal contain more methane gas, and better strategies for removing the methane will need to be developed. Methanotrophic microorganisms offer a novel alternative since they physically remove the methane, are commonly found in soils, and already have been found to exist in many foreign coal mines. Proposed applications of this concept include the inertization of buffer zones separating active mining areas from sealed gobs, reducing ventilation from ventilated gobs and reducing methane content from longwall gobs. Current work includes an assessment of the abundance of naturally occurring methanotrophs in U.S. mines, testing the amount of methane that various types of microorganisms can consume, studying the effects or use of the byproduct gases, and finally developing practical appl ications of this biotechnology to coal mining. This paper reports on the initial laboratory testing that measured the quantity of methane consumed by two types of methanotrophic microorganisms. Average rates of methane consumption were between 1 and 4 ml/hour in column flow tests. A possible gob application may require that 750 cfm of methane be consumed during periods of maximum outgassing. It is premature at this time to accurately scale from laboratory to mine application.

Jan 1, 1991

By Michel Grenier, Gopal Kunchur, Stephen Hardcastle

This paper presents the findings of a dust study in a typical fluorspar processing plant. The primary purpose of this study was to identify employees and occupational groups exposed to high dust levels and determine compliance with personnel regulations for regular and extended work shifts. The range of airborne concentration of respirable silica and fluoride compounds in specific areas and on personnel was determined. State of the art dust monitoring equipment and tracer gas techniques were used to measure dust concentration, pinpoint dust sources and map major airflow trends in the mill. Results of the survey indicated silica dust concentrations in excess of permissible limits being produced mainly by crushers at the south end of the building. Tracer gas releases and gas chromatographic analysis further showed that prevailing south to north air currents tended to carry and spread dust produced by the crushing operations throughout the process plant. Airborne concentrations of fluoride compounds measured during the study were always well below the prescribed threshold limit value (TLV) for the contaminant. Recommendations, including a mechanical exhaust ventilation system on crushers and transfer points, scheduled preventive maintenance on existing bar sprays and wearing of personal protective equipment were made which significantly improved the work environment. Further testing conducted after Installation of the dust extraction system revealed significant improvements in most areas of the mill.

Jan 1, 1991

By Y. C. Kim, M Nataraja, J. T. Buckley, D. H. Tiktinsk

The Nuclear Waste Policy Act of 1982 (NWPA) assigns the U.S. Department of Energy (DOE) the responsibi1it.y of locating, constructing. operating, closing and decommissioning a nuclear waste repository. Prior to submittal of a licensee application to the U. S. Nuclear Regulatory Commission, the DOE is required by 10 CFR part 60 to conduct a program of site characterization for the site to be described in such application. Site characterization includes an exploration and research program in the field and laboratory to determine the geologic conditions and ranges of those parameters which are necessary for determining the suitabi1it.y of the site as a geologic repository. The information thus collected should be able to establish with reasonable assurance that the public and environment will be adequately protected from the hazards associated with a repository at the site. This paper demonstrates by example a geostatistical approach which, on the basis of the existing limited data base, can be used to evaluate (1) whether existing information on a certain parameter is adequate to be considered representative. (2) if additional information is required, where should the additional sampling or testing be performed, and (3) whether the new1.y acquired data along with the existing information constitute representative data.

Jan 1, 1986

By A. de Ferran

Is the Brazilian gold rush over? Judging from the situation in Brazil over the past few decades, the answer is almost certainly yes. The picture of swarms of Brazilian prospectors or "Garimpeiros" crowding or, more correctly, overcrowding the gold regions of the Amazon jungle using the time-aged empirical approach to gold exploration has finally run its course. There are two fallacies that have lead to a reduction in the discovery of new gold fields in Brazil. The first fallacy is that "Brazil's geology is largely unknown." The extreme depth of weathering and the general lack of understanding of the shield deposits are at the origin of this misconception. The second fallacy is that "Brazilian prospectors ("garimpeiros") are very naive, have very little technical knowledge and can only produce gold at very low recovery rates." This is more of a result of wishful thinking for the purpose of justifying limiting exploration programs than it is a real consideration. In this paper, the author takes a methodical heuristic approach to gold exploration in Brazil and offers this as an alternative to the empirical approach of the garimpeiros.

Jan 1, 1998

By G. Mbuyi Kamba

Literature is rather abundant on the topic of steady-state network analysis programs. Many versions exist, some of them have real extended facilities such as full graphical manipulation, fire simulation in motion, etc. These programs are certainly of great help to any ventilation planning and often assist the ventilation engineer in his operational decision making. However, what ever the efficiency of the calculation algorithms might be, their weak point still is the overall validity of the model. This numerical model, apart from maybe the questionable application of some physical laws, depends directly on the quality of the data used to identify its most influencing parameters such as the passive (resistance) or active (fan) characteristic of each of the branches in the network. Considering the non-linear character of the problem and the great number of variables involved, finding the closest numerical model of a real mine ventilation network is without any doubt a very difficult problem. This problem, often referred to as the parameter adjustment problem, is in almost every practical case solved on an experimental and "feeling" basis. Only a few papers put forward a mathematical solution based on a least square approach as the best fit criterion. The aim of this paper is to examine the possibility to apply the well-known simplex method to this problem. The performance of this method and its capability to reach the global optimum which corresponds to the best fit is discussed and compared to that of other methods.

Jan 1, 1995

By Peter H. Grimley

It is important to realize that lending institutions have a very different risk-profile from that of an equity investor. For bank financing, a feasibility study must address the concerns of the lender and these can be summarized under the four 'PI Is: Project, Performance, Product and People. Generally, feasibility studies focus on the measurable project risks associated with a new venture, but frequently insufficient emphasis is placed on key risk areas such as ore grade and metallurgical recovery. Before accepting full or even partial non-recourse risk, financial institutions will demand evidence that the project was constructed according to specifications and within budget and that its Performance within agreed limits has been demonstrated. Product risk should be discussed in detail in any feasibility study. For industrial minerals, penetration of the market can be critical to success and for commodities with volatile prices, the sensitivity of the cash flow to a range of prices should be carried out. Methods of reducing price risk such as long term contracts or, in the case of gold, forward selling should be carefully evaluated. The People risk is rarely discussed in feasibility studies, but can be a key element. Few projects turn out to be faithful copies of the study and the ability of the operator to identify

Jan 1, 1988

By A. E. Hall

INTRODUCTION Underground gold mining operations are found in South Africa, U.S.S.R., Canada, the United States, Zimbabwe, Ghana , Brazil. Australia, China and many other countries. The methods used for extraction differ from highly mechanized trackless mining in the developed countries to the labour intensive systems of the third world nations. The climatic conditions in which mines are situated vary from equatorial to arctic. The rock temperatures and the depth of workings also vary significantly from shallow to extreme depth. The Western Deep Levels mine in South Africa is the deepest and exceeds 4.000 metres in depth with strata temperatures above 55°C. These major differences between mining fields result in significantly different ventilation problems in underground gold mines. The ore types also vary and some deposits have high silica contents while other mines extract sulphide ores. Methane may also be encountered in underground gold mines and can have a large influence on the ventilation practice. Several topics are currently of concern to operating mines and are reviewed here:- a) Air circulation and fans b) Mine cooling c) Permafrost operations d) Mine heating e) Control of diesel exhaust f) Gases, fires and explosions

Jan 1, 1988

By Pentti Kallio

From the aspect of economic feasibility of mining, ineffective use of expensive mechanization investments is becoming a problem. In many cases, the machinery is in operation only 50 - 60 % of the total working time. The lost time when the machines are idle means a considerable over-investment in machines. The lost time, with LHD equipment in particular, accumulates from the following constituents: - the needs of the person operating the machine trips to the work site, lunch, coffee and other breaks, want for comfort, etc. - deficiencies in the monitoring and control systems for machine operation waiting periods at loading and unloading stations, unnecessary and erroneous actions, inefficient work, etc. - deficiencies in the machine condition monitoring system , and inefficient service and maintenance work The data transfer and computer technology of today provides means for resolving problems in several areas - including the area of underground loading operations. In the paper those areas of automation and data handling are considered which make possible an improvement in the usage and monitoring of LHD equipment. These fields are: remote control of equipment, use of TV cameras and monitors in remote control, locating equipment and data transfer down the mine, measurement of the load and the data storing system, systems for following the condition of the equipment, unmanned operation of equipment.

Jan 1, 1989

By Firoze E. Katrak, John R. H. Black, Paul R. Ammann, Michael J. Loreth, Servi. Italo S.

Germanium is produced primarily as a by product from zinc concentrates. The important sources of gallium are alumina ores (bauxites) and zinc concentrates and residues from zinc processing. In addition, gallium as well as germanium may soon be recovered from a depleted copper mine near St. George, Utah. The major uses for germanium are in semiconductors, lenses in infrared optical systems, catalysts, and gamma radiation detectors. The major markets for gallium are in light-emitting diodes, solar cells, laser diodes, integrated circuits, microwave devices, and magnetic bubble memories. CRA projects a healthy growth in the demand for both metals. However, the role of scrap metal will continue to be important over the next decade, thus decreasing the overall demand for primary gallium and primary germanium. This paper summarizes the key elements and the economics of the markets for germanium and gallium. Much of the information, such as plant-by-plant costs of production and estimates of consumption by end use for various countries is from proprietary databases of Charles River Associates.

Jan 1, 1986

By Michael Gauna, William J. Gray, Joseph C. Zelanko

Mechanized mining in the underground coal industry has continued to evolve since the introduction of the remote control mining machine. Remote control continuous mining machines without an onboard operator’s compartment are now the norm in the industry. Extended cuts in excess of 30 ft (9.1 m) are commonplace. Unfortunately, machine operator positioning has become an often unrecognized safety concern, particularly when remote control continuous mining machines excavate a turn (turn a crosscut). From January 2001 through July 2004, remote control continuous mining machine operators or helpers have been involved in ten roof fall fatalities and eight machinery crushing fatalities. The machinery crushing incidents occurred when machines were being repositioned or moved to another place. Of the ten roof fall fatalities, three occurred while a crosscut was being turned and a fourth fatality occurred while mining was being conducted adjacent to the crosscut. The operating time associated with turning crosscuts is a relatively small part of the mining cycle. In recent years, however, a disproportionate number of fatal incidents appear to have been associated with this activity. Procedures for reducing the incidence of operator fatalities while turning crosscuts are discussed. These techniques include: minimizing the number of turn cuts, limiting turn cut depth, establishing no work zones and using visual warning devices to designate them, installing more roof/rib support in the vicinity of the turn cut, using notch cuts prior to initiating a full turn cut, and positioning the remote control miner operator in nontraditional locations.

Jan 1, 2005

By Victor F. Hollister

This section includes examples of discoveries of Kuroko- and Anyoz-type massive sulfides, and shale-hosted, zinc-lead deposits, and describes exploration models for each group of case histories. Exploration or empirical models can differ from genetic models, because ore guides and controls are emphasized in exploration models. Genetic models may form the scientific basis for exploration or prospecting models, although factors that are important to the localization of ore are stressed in exploration models. The paper by Sato (abstracted herein) on Kuroko deposits can be used as a general exploration guide for that type of deposit. It is clear, however, that no unambiguous stratigraphic control for Kuroko-type ore is given in the Sato paper. The paper by MacIntyre (an excerpt herein) describing Gataga, Midway, and Windy Craggy includes most of the elements of the shale-hosted and Anyox models. Although more recent work by the Geological Survey of Canada has modified the Windy Craggy stratigraphy, the Anyox model as applied to Windy Craggy is well described in the MacIntyre (1983) paper. Discoveries of ophiolite-, Ducktown-, volcanic-associated Ni- Cu-, and Besshi-type deposits are not included in this section. Conformable massive sulfide deposits are generally assumed to be syngenetic. Sulfides in the crosscutting feeder zones, however, are classed as epigenetic. Therefore, volcanogenic massive sulfides can contain both a syngenetic and an epigenetic component. Vital to the development of the epigenetic component is a heat source that propels the convection cycle that forms both components. In all massive sulfide discoveries described in this section, it is assumed that a volcanic magma fueled the hydrothermal fluids.

Jan 1, 1991

By John W. Ahlrichs, E. Daniel Baker, Erich U. Petersen, William J. Tafuri, Douglas N. Halbe

The combined Bootstrap and Capstone deposits, located in the Bootstrap subdistrict (Section 10, T36N, R49E, M.D.B.M., Elko County, Nevada), are approximately 27 miles northwest of Ca-1I: Nevada. The contiguous Bootstrap Capstone deposits are located along the northeastern and northern flanks of Round Mountain, a horst block separated by grabens from the sheep Creek Mountains to the north-northwest and the Tuscarora Mountains to the east. Open-pit-minable gold reserves as of December, 1989, were 13.27 million short tons with an average grade of .057 troy ounces gold per ton and an overall waste-to-ore strip ratio of 2.5:1. Ore zones in Bootstrap are concentrated along north striking high-angle dikes localized along faults, while ore zones at Capstone are strata form and structural, occurring at the Devonian limestone/siliceous sediment interface and in high-angle fault-filling dikes. Pre-ore faulting produced a complex structural setting for Capstone, dominated by strong northwest fault sets cross-cut by northeasterly structures. Alteration associated with both deposits is silicification with a-strong argillic overprint. Dike emplacement, which post-dates silicification, marked the onset of mainstage gold deposition and argillic overprinting of silicified lithologies. Gold displays an affinity for moderately argillized sedimentary and igneous lithologies. Mineralogic and geochemical analyses of rotary percussion drill samples show good correlation between gold, silica, antimony, and arsenic.

Jan 1, 1990

By M. Misra, I. Anazia

The dispersion of oily collector has a significant effect on the flotation recovery of ultrafine coal. Generally, reagent dispersion is accomplished by mechanical mixing and/or ultrasonic agitation, followed by direct addition of dispersed collector into the flotation cell. Such dispersion and reagent addition techniques are invariably inadequate and nonselective. A new collector addition technique involving gas phase transport of atomized collector has shown improved results when compared to conventional reagent addition techniques. This technique involves atomization of the collector into the air stream. Under these circumstances, an aerosol is introduced into the flotation cell. Initially, the oil is dispersed within the air phase (continuous with respect to oil), and the air phase is dispersed within the pulp (continuous with respect to aerosol). In the flotation cell, the atomized oil droplets coalesce on the bubble's surface and create a de facto oil-encapsulated bubble. This approach provides excellent dispersion, increases selectivity, and, most significantly, increases the flotation rate of ultrafine coal. Atomization of collector/frother combinations yielded improved flotation recovery and maintained near uniform froth levels, which is a desirable feature in coal flotation. Microscopic examinations of the attachment of oil- coated bubbles at a coal surface were conducted by attachment time and contact angle measurements. Oil-coated bubbles attach at significantly faster rates and with a higher contact angle than oil-free bubbles.

Jan 1, 1988

By P. C. Cochrane, I. S. Clelland, S. H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, NM, area. The first four shafts sunk at International Minerals and Chemical Corp. (IMC) property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 shaft there has been extensive erosion and salt dissolution in the Rustler Formation, leading to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows. It was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be modified to reflect any new or additional information obtained during the progress of the grouting.

Jan 1, 1987