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By Robert C. Jones

The Henderson Mine, a new large scale underground development, is being developed by AMAX. The mine site is located about 50 miles west of Denver, Colorado, adjacent to the east side of the Continental Divide. The mine's three access shafts are in a narrow alpine canyon at an elevation of 10,400 feet. The ore body of molybdenite is to the south of the shafts, 3,000 feet below the surface of nearby Red Mountain. The ore extends over 800 feet vertically and is about 1,700 feet by 2,200 feet horizontally. The eastern and southeastern boundaries of the deposit are still to be defined at the present time. Development mining is advancing at the mine site on a three shift, seven-day basis at the rate of about 2,000 feet per month. About twelve miles of heading have been driven at the present time, and work to sink No. 3 Shaft has started. Development mining was begun in 1967 with the sinking of No. 1 Shaft. This shaft is fully concreted, 23 feet in diameter and 2,441 feet in depth. It is the mine ventilation exhaust conduit. It is also used for development muck hoisting, stand-by mine water pumping and secondary access to the 8,035 foot level. This level is the mine exhaust ventilation level and was mined principally by conventional rail mining methods. From this one station at the 8,035 foot elevation a 5% ramp was driven to the initial production horizon at 8,100 feet with diesel rubber tired mining equipment. Subsequent mining has been entirely by mobile diesel equipment at the mine site.

Jan 1, 1974

By E. Finch

Beneficiation tests were conducted on samples from three ore zones in the Los Monos, Navay orebody in Táchira State, Venezuela as part of an overall feasibility study. The scope of work included ore sample characterization, flowsheet development, and optimization of beneficiation variables on a bench scale followed by confirmation on a pilot plant scale. Phosphate in the ore samples occurred primarily as francolite and was associated with quartz, kaolinite, and feldspar. Liberation of the phosphate began at 589 microns (28 mesh) for the main ore zone sample and at 295 microns (48 mesh) for the lower-grade ore zone samples. Development tests on simulated mining composites demonstrated that the samples responded well to 589 micron (28 mesh) grinding, two stages of high intensity scrubbing, conditioning at high % solids with caustic and equal amounts of tall oil and fuel oil, and separate coarse and fine flotation circuits with one stage of roughing and two stages of cleaning (reflotation). Concentrates in the range of 31.5-34% P205 with recoveries from 64-70% were obtained from the mining composites. Product quality for all concentrates in the range of 31.5 % P205 was good; 1.40 CaO/P205 and 0.04-0.05 minor element ratios. Confirmation testing in a continuous pilot plant produced results similar to those achieved in the laboratory.

Jan 1, 1993

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 Henry R. Tiedemann, Eugene H. Skinner, George E. Wickham

Improving the state-of-the-art of tunneling is a continuing challenge to those involved in underground construction. New methods and procedures are usually evolved over a relatively long period of time as compared to advancements in other types of construction. To a large extent this is probably due to the fact that tunneling deals with a material or medium - the rock structure - whose physical properties are not only extremely varied, but in many instances virtually unknown until time of penetration. This hovering of the unknown tends to make "non believers" of many and at best leads to a general reluctancy of accepting new ideas or procedures. The situation is further complicated by: 1) discrepancies in terminology and respective meanings as used by different disciplines to describe, define or evaluate pertinent factors and their relative effect on the tunneling process and 2) the fact that no two tunneling situations are identical with respect to either geological conditions or construction and contractual requirements. In spite of the above there have been many successfully completed tunnels which make it apparent that both the technical and practical expertise needed to develop or project improvements is available within the industry. It is with this in mind that the RSR concept was developed. BACKGROUND This paper presents the findings and results obtained from contin-

Jan 1, 1974

By Hu Wenjun, Li Maonan

Mine ventilation systems mostly are ventilation networks with fixed-quantity branches. The solution to the problem of ventilation networks with fixed-quantity branches is obtained by choosing the fixed quantity branches as chords and using Hardy Cross iteration method. The solution usually is feasible but may be not economical. This paper takes minimal annual ventilation electricity cost as an object, considering the power of main fans and boosters, natural ventilation pressures and resistances of regulators, and builds up a nonlinear programming model. A set of initial values of the nonlinear programming can be obtained by using Hardy Cross method, The MAP technique then used to find a set of local optimal solution The running procedure with a simple example is dicussed. Mine ventilation systems mostly are ventilation networks with fixed quantity branches. In the networks, air quantity of branches are generaly regulated by increasing branch resistance or air pressure. A comon approch to the of the networks with fixed quantity branches is to formulate it based on Kirchhoff's current and voltage laws and the solution is obtained by Hardy Cross iterative technique. The solution usualy is feasible but may be not economical. The optimal plan of air quntities regulation of mine ventilation network should be to make the solution satisfy both required quantity of work places and minimal ventilation operating cost. It is the purpose of this paper to introduce a new approch and computational experience of nonlinear programming of the optimal problem.

Jan 1, 1991

By Arthur E. Lord, W. Martin McCabe, Robert M. Koerner

Following the driving of each new section of tunnel, a prompt decision is required regarding the type and extent of primary support to control convergence and prevent ground failure. Sometime thereafter, the effectiveness of the in-place support must be evaluated over the entire length of excavation. It is therefore extremely desirable to have available a lightweight, portable, easy to install and interpret, cost effective monitoring system to assist with these ground control functions. Such a system can be assembled based on the acoustic emission (or microseismic) technique. This monitoring technique uses a piezoelectric transducer to detect subaudible noises associated with deformation of and/or crack propagation in the soil or rock being monitored. After detection, the signals are then amplified, filtered and electronically counted to provide a quantified assessment of the stability of the structure. In the simplest sense, the absence of emission, or counts, signifies no deformation and thus stability. Conversely, the occurrance of counts signifies instability to varying degrees. The higher the count rate, the greater the instability and the need for immediate or additional support. Described in this paper is an overview of the acoustic emission (microseismic) method, details of its use in a laboratory study measuring convergence and stand-up time in soil, and the behavior of rock samples under similar stress conditions. Field use of the method is recommended for ground control monitoring in tunnels, and some suggestions regarding monitoring procedure are presented.

Jan 1, 1979

By Don U. Deere, Edward J. Cording

INTRODUCTION Observations during construction form an integral part of the design and construction of major underground works. Observations as used herein include visual inspection, detailed geologic mapping, and correlation of geology with support conditions, as well as instrumentation to provide more precise information regarding rock movements and support load. This paper describes the application of an observational program to one of the more difficult design and construction problems underground -- the excavation and support of large chambers at shallow depth in rock of variable quality. Emphasis on underground construction for subways and utilities in urban areas is bringing this problem to increased prominence. It is our intent to focus on the design and construction problems associated with such excavations and to describe observational methods which can be employed to aid in their construction. Observational programs may serve two purposes. One is to monitor the rock and support conditions in order to provide early warning of potential construction problems. Such a program should be routinely used in critical locations on major underground excavations of the type described in this paper. The program should be closely coordinated with the inspection effort and construction control. The other purpose is to provide detailed information regarding the interaction of support conditions and rock displacements to aid in development of more efficient design and construction procedures on later projects. For this purpose, instrumentation might be concentrated in special test sections where specific and typical

Jan 1, 1997

By Philip A. Mattson

INTRODUCTION Engineers involved with rock mechanics know the importance of discontinuities within a rock mass and their effect on its behavior when subjected to loads from structures or construction excavation activities. Various geophysical tools have been developed to provide comparative information on subsurface conditions, such as electrical resistivity, assorted seismic test methods, acoustic tests, etc. While these investigative means have proved invaluable in numerous situations, especially those where site alternatives are being evaluated, they shed little light on the difficult problem of quantifying the rock strength. For that purpose, a laboratory test program of samples obtained in the field is usually undertaken, often in conjunction with a variety of in-situ tests. While standard samples provide sufficient information on the rock properties, questions on the macro-structure of joints, faults, fissures, and their infillings often go unanswered. Presently, attempts are being made to incorporate into rock sampling technology new techniques which are directed towards providing better information on the incidense and orientation of discontinuities. One such device incorporates a scribe knife within the core barrel which scores the sample lengthwise as it is cored. The orientation of the scribe is known, thereby relating the bedding, planes, fractures, etc. to a spatial framework. A second approach, called the Integral Sampling Method, is the subject of this paper. Stated briefly, this method utilizes a grout injection to bond fractured rock to a steel reinforcing bar at the center of the coring. The bar is intended to act as a

Jan 1, 1979

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 R. Addison, P. V. Avotins, D. W. Kestner, M. F. Dibble, L. A. Haas, M. D. Flavel, D. Halbe, D. J. Barratt, G. V. Jergenaen

Mineral processing in 1980 can be described by several key words, familiar to the industry throughout the past decade: complex, low grade, environmental, energy, high tonnage, and economics. Flowsheets have become more complex in order to treat lower-grade, finer-grained, more complex ores and still meet environmental and economic constraints. Operators and researchers have had to cope with these problems, which have resulted in marked trends in mineral processing. The use of advanced instrumentation in process monitoring, control, and modeling has been increasing to deal with fluctuating ore grades, higher plant capacities, rapidly rising operating costs, and process complexities. The industry has been presented with new generations of equipment that reportedly do the job more efficiently and at a reduced cost. The need to meet stricter air and water environmental standards has resulted in a concerted effort by the mineral industries to obtain an appropriate balance between the needs of mining and mineral processing and the requirements for proper environmental, safety, and health protection. Energy and economic considerations have led to increased equipment size, particularly in grinding, flotation, and conveying. Throughout all phases of mineral processing there has been an effort to reduce energy consumption. One avenue followed by researchers and operators was the testing and use of chemicals to reduce energy requirements.

Jan 5, 1981

By J. W. Hawkins

Understanding aquifer properties in surface mine backfill is essential for managing the groundwater flow system as well as controlling the formation and discharge of acid urine drainage. Slug tests (injection and withdrawal) performed on wells in mine spoil may yield two distinctly different response characteristics. One type of response is indicative of a porous media system. The second type of response indicates the presence of a pseudokarst system. The presence of voids or conduits in the backfill is indicated by an almost instantaneous partial recovery of the water level displacement. This rapid recovery is turbulent flow and cannot be analyzed by conventional (Darcian) methods. The turbulent flow may cause the calculated hydraulic conductivity to be less than the actual values. The slug dissipation surface area created by the voids contiguous to the test well add to the known dissipation surface area of the screened interval. This can cause the calculated hydraulic conductivity to be greater than the actual hydraulic conductivity or the aquifer to appear more permeable. Whenever analyzing data from aquifer tests in mine spoil, these potential problems must be kept in mind. In spite of the problems encountered during slug testing of spoil, the aquifer hydraulic parameters derived and the slug responses observed remain useful in the hydrologic characterization of a mine site.

Jan 1, 1994

By Bruce D. Hulman, Robert .. F. Gorman

Introduction Groundwater resource evaluation has historically required extensive field investigative work, usually at great cost. More recently, the advent of the microcomputer has made difficult aquifer and groundwater evaluations comparatively simple and less expensive. A groundwater model is a numeric solution to a set of equations that calculates the water level in an aquifer or other types of water bearing strata. A computer will execute the solution of the set of equations rapidly and thereby permit evaluation of large amounts of hydrogeologic data rapidly. Computer modeling of groundwater resources is very often used to forecast the effects of multiple uses of a single groundwater resource. Modeling of heavily used aquifers has proven to be beneficial for averting problems arising from competitive use of a groundwater resource. This paper describes the work tasks performed in order to evaluate a large alluvial aquifer and thereby predict the hydrologic impact of additional groundwater withdrawal. Purpose and Scope Neyer, Tiseo & Hindo, Ltd. (NTH) was retained to evaluate the groundwater supply potential of the Missouri River alluvium underlying the Fairfax District in Kansas City, Kansas (Figure 1). The proposed groundwater supply is being considered for industrial use as non-contact process water and a heat exchange medium for plant climate control. The anticipated peak groundwater demand is estimated to exceed 30 million gallons per day (MGD) during the summer months, with an average daily demand of nearly 25 MGD. The proposed groundwater supply was to be developed from 15 large-diameter production wells located at positions that would minimize potential interference.

Jan 1, 1987

By Gerhard Sauer, Heimo Gold

The main advantage of the New Austrian Tunneling Method over conventional drill and blast techniques, TBMs and shields is its outstanding flexibility. Many different support concepts help to cope with all but the most adverse conditions. A considerable variety of unique additional support measurements provide a functional tool when dealing with particularly difficult conditions or restricting requirements. The resulting adaptability of NATM with respect to geometric and geologic changes is a cornerstone to providing an economic design and to a safe and unhindered execution of the tunnel work. To take best advantage of this flexibility and to emphasize its cost-saving capacity, NATM explicitly extends the design period into the construction phase. In accordance with corresponding ground classes or other anticipated conditions, a number of basic support categories and an array of additional support measurements are established during the actual design phase. The decision for applying a particular support category at a specific location and for necessary additions to the given support scheme, however, is regularly made on site after each advance, and is determined by the key persons involved in the construction. Contract documents must reflect this approach to facilitate the execution of the work and to curtail construction costs. Biased distributions of risks, however, can adversely effect the envisioned benefits. Consequently, the respective responsibilities of engineer, contractor, and client need to be redefined.

Jan 1, 1989

By Robert A. Haney, Scott G. Vail, Kenneth G. Fields

The Mine Safety and Health Administration, in cooperation with IMC Global Operations, Inc., conducted a joint study to determine the effectiveness of the technology currently in use at the mine to control diesel particulate exposures. IMC Global operates an underground potash mine using diesel-powered equipment to extract minerals. IMC uses a variety of technologies to control worker exposures to diesel particulate. These technologies include: ventilation, low sulfur fuel, oxidation catalytic converters (OCC), maintenance and work practices. The study was conducted over a two-week period, two shifts per day. During the first week (six shifts), baseline data on exposures and diesel particulate emissions were obtained. New OCC's were installed over the weekend on all equipment on the test section. During the second week (six shifts), data were collected to assess the effectiveness of the new OCC devices. In addition to exposure and diesel particulate emissions data, mine ventilation, engine exhaust temperatures and mine operational data were obtained. The primary means of determining diesel particulate concentrations was the respirable combustible dust (RCD) method. Gas concentrations carbon monoxide (CO), carbon dioxide (CO,), and nitrogen dioxide (NO,) were measured using passive dosimeter badges and gas bottles. Results of measurements of diesel particulate, gases, and air- flows were analyzed to determine the effectiveness of airflow and oxidation catalytic converters for controlling diesel particulate exposures. The use of oxidation catalytic converters resulted in reductions of both workers' exposures and diesel emissions.

Jan 1, 1997

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 Luís Tavares Ribeiro

Nowadays there is a greater need for detailed reservoir modelling in the oil industry. It is generally recognized that nearly all reservoirs are heterogeneous and idealization of rock characteristics in flow calculations is unrealistic regarding actual physical and textural conditions encountered in geologic formations. The heterogeneity of oil reservoirs considerably influences the distribution of fluids, as well as their displacement. It would be advantageous if a reservoir petroleum engineer was able to construct a precise mathematical model of the detailed reservoir rock variability characterizing the degree of reservoir heterogeneity in an unambiguous way. This paper presents a geomathematical model describing the spatial behaviour and distribution of the principal reservoir properties. The model is based on the Theory of Regionalised Variables and the Kriging technique. The model is performed by a set of computing programs and is tested on an Abu Dhabi oil reservoir in United Arab Emirates.

Jan 1, 1986

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 Michael J. Sapko, Robert A. Cortese

A flame powered trigger device has been developed to explosively activate suppression barriers to quench gas and coal dust explosions. The important feature of the device is a silicon solar panel, which collects 0.3 p to 1.1 D wavelength radiation from the developing explosion, and generates electrical energy to initiate a detonator, which in turn causes the rapid explosive release of an extinguishing agent into the advancing flame front. Solar panels that are rated to produce 20 w of electrical power when exposed to the sun light are producing about 200 w when exposed to full-scale dust explosion propagating in the U.S. Bureau of Mines' Lake Lynn Experimental Mine. The solar panel is electrically isolated from the detonator by a pressure sensitive switch until the arrival of the precursor pressure pulse, which always precedes a deflagration. This combination of pressure arming and flame powered photo generator prevents false barrier activation and requires no external power supply.

Jan 1, 1991

By S. K. Kawatra, T. C. Eisele

Pyrite depression is of great interest in sulfide mineral flotation, where pyrite is a common gangue mineral. Since the floatability of pyrite is a function of the pH and a variety of other chemical factors, pH control is a critical part of sulfide flotation circuits. A wide variety of pyrite-depressing chemicals have been studied and used in sulfide- mineral processing, with considerable success. However, there are certain applications where there are still no satisfactory pyrite depressants, and even when suitable depressants are available, there is always a need for less-expensive reagents. Microorganisms, such as the bacteria Thiobacillus ferrooxidans, are known to depress pyrite flotation. However, the dependence of the depression on the type of organism or on suspension pH is still being determined. In this study, the relative effectiveness of various microorganisms, and the effect of pH, has been examined. Screening tests using microflotation showed that every microorganism tested was capable of depressing naturally hydrophobic pyrite at acidic pH. Larger-scale experiments with two of the screened organisms and two different pyrites showed that microorganisms are very effective depressants at acid pH, but are largely ineffective at neutral and alkaline pH where the pyrite surface is not naturally hydrophobic.

Jan 1, 1994

By John C. Galloway, Heinz G. Leistner

ACKNOWLEDGEMENTS The investigations described in this paper were supported by contracts with the Defense Nuclear Agency (DNA) under direction of Lt. Col. John Galloway, and by Boeing Company research funds under supervision of James Wooster. Other engineers of The Boeing Company who contributed to the work of this investigation were Don Armitstead, John McAvoy, and Tom Day. INTRODUCTION In this paper, we are describing a current concept for placing intercontinental ballistic missiles (ICBMs) in sites deep underground to be used as a strategic Future Secure Reserve Force (FSRF). The objective of such concepts is to utilize soil and rock cover to protect high value strategic weapons from destruction by nuclear attack. The burial deep underground achieves two purposes. First, it imposes a miss distance upon the attacking weapon equal to the depth of burial minus any penetration capability the weapon might have. This tends to offset increasing accuracy of weapon delivery. The other purpose is to absorb as much of the weapon's energy as possible, thus reducing the effects of powerful weapons. This use of soil or rock cover over military facilities began with the development of man's capability to loft projectiles. Until recently, underground military installations, by their nature, performed defensive functions. Since they are not mobile and their weapons in the past had very limited range, an enemy would have to approach them before an engagement could take place. Thus, they were often used to control "choke points" on sea lanes as in the case of Gibraltar or

Jan 1, 1979