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By Alice Blount, F. Patrick Carr

The quantitative evaluation,of quartz and other minerals in acid-insoluble residues from carbonate rocks and other industrial mineral products derived from sedimentary and low-grade metamorphic rocks is difficult. Commonly there are a dozen or more minerals present, and the suites vary from sample to sample. Because of these factors, either the absorption coefficient must be determined on a sample to sample basis or an internal standard must be used. Internal standards in general use are unsatisfactory. For example, [A1203] is often present in product samples because of ceramic grinding elements used in their production; CaF and LiF have peaks which overlap or nearly overlap mineral peaks in the samples. A careful evaluation has shown that magnesium aluminate (synthetic spinel) works particularly well as an internal standard for these types of samples. Not only does it have few, strong diffraction peaks which do not overlap, the peaks are in the same 28 region as the minerals, usually quartz and silicates, for which quantification is desired. Spinel also consists of equidimensional particles without prominent cleavages; this promotes a random orientation of the minerals in X-ray diffraction mounts. In addition, spinel can be used to correct for loss of diffracted-beam intensity due to thin sample preparations which are often unavoidable.

Jan 1, 1991

By Roshan B. Bhappu, Sukhendu L. Barua

The economics of developing and operating small precious metal mines are unique and require much more scrutiny than larger mines since a limited tonnage must carry a heavy burden of capital investment as well as operating cost per unit ton to be mined and processed. Moreover, potential operators of small mines do not have the required expertise available to critically evaluate the technical and economic aspects of their projects. In this paper, the authors have attempted to provide technical and economic guidelines for developing and operating small precious metal mines. Capital and operating cost estimates as well as return on investment are provided for various scenarios utilizing different mining and processing techniques.

Jan 1, 1987

By Jan M. Mutmansky

While production scheduling for both surface and underground mining operations is similar in nature, a rather large array of techniques is applied in solving such planning problems. The techniques consist of both rigid operations research (OR) methods and practical procedures which are not mathematically based. In the following sections, a short summary of some of the techniques that are applicable to production scheduling problems in mineral operations is presented. The techniques discussed are: linear programming, integer programming, dynamic programming, graph and network theory, simulation, and heuristic methods. For an in-depth comprehension of these techniques, the reader is referred to any of the available textbooks on these subjects. One or more references will be listed for each topic to provide a starting point.

Jan 1, 1979

By V. G. Papangelakis, G. P. Demopoulos

The high temperature (180-200 OC ) pressure oxidation (02 - HzSO4) process for the recovery of gold from refractory concentrates (FeS2/FeA8S) is simulated with the aid of a computer model. The model centers on the continuous operation of a multi-stage horizontal autoclave. In particular the effects of key process parameters controlling the autogenous operation of the autoclave are critically examined. The building elements of the model are (i) the continuous particle size distribution function of the concentrate, (ii) the residence time distribution function of the slurry and (iii) the shrinking core kinetics. Conversion is calculated on the basis of the segregated flow model. For the calculation of the particle size distribution at the exit of each compartment the population balance model is employed. The effects of feed rate, feed preheating, cooling, autoclave configuration and rate limiting regime (chemical reaction vs. gas-liquid mass transfer) on the autogenous steady state operation are discussed. Finally optimum reactor design and operation criteria are indicated.

Jan 1, 1990

By I. Shah, L. G. Austin

A method for quantitative investigation of the phenomena involved in fine grinding of materials that follows the changes in the breakage rates of fine particles has been presented. For relatively hard, brittle, non-coating material like quartz, the slowing down effect of breakage rates starts to be significant at relatively coarse sizes, which goes often undetected in closed circuit grinding systems, producing relatively coarse product, say P80=75µm However, for fine grinding systems, as the -10µm fractions begin to build-up, and classification becomes more difficult, the build-up of fine sizes causes a slowing down effect Compounding this problem is the difficulty of obtaining accurate cumulative weight size distributions in the fine size region.

Jan 1, 1983

By Gary S. Brierley, Ronald E. Romley, Alan L. Howard

The Price Road Drain Tunnel in Tempe, Arizona is part of the drainage system constructed in conjunction with the Outer Loop Highway in metropolitan Phoenix. The Outer Loop Project is a part of a much larger expressway system that includes other large drainage tunnels such as the Papago Freeway Drain Tunnels. Large diameter downhole inspection borings were utilized to obtain subsurface data for the design of these tunnels. Subsurface data obtained from the large diameter borings resulted in the development of empirical parameters that were successfully incorporated into the Geotechnical Design Summary Report and which satisfactorily predicted ground behavior, formed the basis for improved geotechnical design criteria, and facilitated the cost effective assessment of third party risk. The purpose of this paper is to describe the subsurface exploration program performed for this project and to explain the methods used to evaluate underground construction procedures.

Jan 1, 1991

By M. S. Prasad, K. J. Reid, M. P. Katsoulis

The State of Minnesota is interested in stimulating the development of clay resources and recently supported a two-year project to collect data on geological, mineralogical, processing, economic and environmental aspects of such potential developments. This paper presents the various process options adopted on bulk samples collected from the Minnesota River Valley area, which is a primary deposit and contains a major silica fraction. A standard test flowsheet involving degritting, dispersion. HGMS and cycloning was developed and for some samples yielded an acceptable filler grade product. Secondary streams containing relatively high grade kaolin but of coarse size were also obtained. Improvement in particle size distribution and in physical properties related to paper product specifications (brightness, viscosity) were obtained by size-reduction processes. Market and economic considerations for kaolin consumption in the upper Midwest are analyzed. Current markets for paper grade kaolin in Minnesota are briefly discussed.

Jan 1, 1992

By Arafat Ghosheh, Yousuf Abu-Rish, Darwish Amara, Mohammed Baderkhan

The Jordan Phosphate Mines Company is one of the world's major phosphate rock and phosphatic fertilizers producers (the second largest phosphate rock exporter), with ore reserves exceeding 2 billion tonnes, mainly located in the Eshidiya area. The Eshidiya phosphate deposits, 120 km north-east of Aqaba, are of sedimentary origin (as are all phosphate ore in Jordan). Three exploitable beds (Al, A2, and A3) with variable content of P205, CaO, SiO2, etc., are processed in order to produce 68-70,73-75, and 75-77% TCP grades. The A3 bed, which is characterized as the most siliceous containing 40-48% TCP, requires physical beneficiation using wet scrubbing, screening, and desliming by hydrocylone, followed by anionic conventional flotation to achieve 75- 77% TCP grade. For the last 15 years extensive laboratory and pilot tests (including physical, chemical, and mineralogical studies) were carried out. After operating the industrial plant, certain modifications were deemed necessary to adjust the operational parameters and the final flowsheet, which was followed to obtain the targeted quantity and quality of concentrate.

Jan 1, 1999

By J. E. Oberholtzer, M. G. Fernald

INTRODUCTION Approximately six years ago the U.S. Bureau of Mines (USBM) developed a data acquisition system (DAS) specifically designed for measuring radon levels and other environmental parameters during studies of means to control radiation hazards in underground uranium mines. The DAS system records data in machine readable form using a paper tape punch, which represented the state-of-the-art at that time for a moderate cost output device. However, the use of paper tape as a recording medium for field studies is somewhat unwieldy. Reducing the raw data required either that the tape be shipped to a computer center equipped with a high-speed paper tape reader or that the tape be transmitted at low speed over the telephone lines to a remote computer. Transmitting, at ten characters per second, the data from a 10-channel DAS taking Four readings per hour would require about 30 minutes For each 24-hour day's data. Telephone lines from remote mine sites are often of marginal quality and data errors can be introduced during transmission. Paper tape punches are also prone to occasional punching errors. Both problems make it necessary to carefully check for and correct data errors, a process which is possible because each DAS produces an independent printed data record, but the error checking and correction process can be quite laborious. Aware of recent advances in microcomputer technology which have brought the price of a personal computer down to about the cost of a paper tape punch 5-10 years ago, the Bureau decided to explore the feasibility of using a low-cost personal computer in the field to process DAS data in real time. On behalf of the Bureau, Arthur D. Little, Inc., developed a simple interface circuit which permits an Apple II computer to accept data from one or two DAS units as it is being transmitted to the paper tape punches. Computer software converts each measurement to appropriate engineering units, e.g., radon concentration, Working Levels, air velocity, temperature, or barometric pressure. The computer also calculates 1-hour and 8-hour running averages of all converted data and prints those results as soon as they are obtained on a line printer located at the test site for immediate inspection. After development, the system was used continuously and successfully for a 5-month period at a Utah uranium mine. DAS DESIGN AND MODIFICATION Each of the two USBM data acquisition systems used in this work consists of two separate modules. A multiplexer module located below ground near the measurement transducers acquires signals from each of nine tranducers. Six input channels were devoted to measurements of radon or Working Level. The outputs of those transducers, photomultiplier tubes or G-M tubes, respectively, are digital pulse trains which are accepted directly by the mutliplexer. Three channels were used for environmental parameters--air velocity, temperature, and/or barometric pressure. Each of the environmental tranducers is fitted with dedicated linearizing and voltage-to-frequency conversion circuitry so that the outputs to the multiplexer are also pulse trains having frequencies of one tenth of the value of the measured parameter expressed in the appropriate engineering units. A 100-Hz reference signal was input into the tenth channel for use in monitoring system integrity and performance. All ten pulse trains are then timeseries multiplexed into a signal line for transmission to the above-ground data acquisition module. Above ground, the composite signal is de-multiplexed into ten separate lines, each of which is connected to a digital counter which converts the pulse train to a numerical value. The acquisition of each set of readings is initiated by an adjustable "scan cycle comparator" timer. The acquisition process proceeds in three phases. First, radon and Working Level channels are counted for an extended period of time, typically 5-10 minutes depending on activity, because of the low pulse rates involved. Then the other four channels are counted for ten seconds, and finally, all ten readings, along with the Julian day and time of day are output serially onto paper tape and printed on a strip printer. When the scan cycle comparator reaches its preset time (15-minute cycle times were used in this work), it resets itself, initiates another readout cycle, and begins timing again. The only modification made to the data acquisition systems used in this work was to disconnect the scan cycle comparator in one unit, which became the "slave" and bring in the scan cycle comparator signal from the other unit, the "master", to initiate data acquisition cycles in the slave. Synchronizing the two data acquisitions in this fashion and using two slightly different radon counting times insured that the two systems never attempted to output data to the Apple II at the same time. THE APPLE II COMPUTER The Apple II computer used in this work was equipped with 48 KBytes of semiconductor random access memory (RAM), two floppy diskette drives, a Centronics Model 730 impact matrix printer and a modulator for driving an ordinary color television as a video display device. A single California Computer Systems Model 7720A dual 8-bit bidirectional parallel input/output (I/O) card was installed in the Apple to accept the digital data from both data acquisition systems. This card is

Jan 1, 1981

By A. C. C. Pacheco, L. C. Bertolino, M. L. Torem

On account of geological characteristics, Brazil is a country of large deposits of high quality kaolin, with the larger ones being located in its northern region. In the last years, kaolin beneficiation and production area is receiving great investments, aiming at a high quality kaolin production to be used in the paper industry, mainly intended for the foreign market. After the conclusion of expan- sion programs and with the advent of new production areas, Brazil is very soon expected to come in second place in the kaolin world production ranking.

Jan 1, 1998

By A. D. Wunderlich

Providing a safe & secure environment for your employees and other company assets is absolutely necessary in our litigeous society. Security hardware is no different than computers or other technical equipment, in that new equipment is developed each year that makes older equipment obsolete. This presentation will help to explain how your existing security system and security procedures can be updated to meet industry standards without the expenditure of a great deal of money. If you are concerned about potential security problems and how to address these problems, this presentation is a must.

Jan 1, 1995

By Clay Haynes, Tim Pearia, Robert Robinson, Judy Cochran

A 1.89 km-long, 4.5 m-I.D. tunnel was successfully constructed through saturated hard clay, and highly abrasive dense sand and gravel, with groundwater heads ranging from 10 to 20 m. In order to address these conditions, a Lovat earth pressure balance TBM was used, with soil conditioning by foam, water and various polymers. Support was provided by a single-pass segmented concrete lining. Groundwater inflows of 400to 1,600 lpm at times created challenges for changing cutting tools. Surface settlements were generally less than measurement thresholds, except under very low cover at startup. This project provides a pivotal case study of the successful application of EPBM technology in saturated, abrasive glacial soils and the successful application of soil conditioners.

Jan 1, 2003

By John T. McDonough

The Climax Mine of AMAX's Climax Molybdenum Division is currently producing approximately 34,000 tons of molybdenum ore per day from two underground levels (see Figure I), and initial design is underway for the next deeper (1200) level. The aim of this report is to present the methods of site evaluation used at Climax for cavability determinations and underground support design. Climax succeeds with its panel caving system of mining (Julin, 1973) (Figure 2) largely because of the presence of pervasive geologic structural discontinuities. The stockwork ore body at Climax was formed by the multiple intrusion of mid-Tertiary rhyolitic magmas into Precambrian granite, schist and gneiss, and the hydrothermal emplacement of molybdenite into the network of fractures that were generated during the forceful upward intrusion of magma. Subsequently, intrusive events that were more deeply seated refractured the overlying, ore- bearing stock and propagated a complex system of axial and radial fractures. Post-ore movement along the Mosquito Fault (Wallace, 1968) and its associated stranded shear zones further fractured the ore body and disordered the existent geologic structure. The result of these structural events is a brittle, crystalline ore body that is transected by a complex pattern of faults, shear zones, and joints that augment cave initiation and enhance comminution of the ore blocks. Generalizations can be made about the structural trends within the ore deposit (King, 1946; Kendorski, 1973), however, the intensity and orientation of geologic structure is by no means uniform throughout the ore body. The relative intensities of silicic and argillic alteration are also highly variable (Vanderwilt and King, 1955). As a consequence, no single rock-mass model suffices as a standard for mine design, and site characterization for cavability and support design is a continuous process.

Jan 1, 1977

By D. Koch

Bentonites and bentonite containing sealing materials are used since many years for sealing purposes in foundation, dike construction, hydraulic engineering and landfill construction, especially for encapsulation of old waste deposits In the near future compacted bentonites will be important components of multi-barrier systems for dry charge of old mines, for underground disposal of hazardous or radioactive wastes. Because of their exceptional physical, structural and chemical properties, bentonites are offering manifold possibilities to protect the environment against the negative effects of dumping grounds. Often the compliance with legal regulations for waste dumping or the isolation of contaminated areas is possible only by using bentonite containing sealing systems. The essential properties of bentonite, bentonite containing building materials and the different techniques of making horizontal technical base liners and vertical cut-off walls are explained. For horizontal technical base liners the adsorption ability, the ion exchange capacity and the swelling behavior of bentonites are important. For cut-off walls bentonite controls the rheological behavior of the slurry and is responsible for the low permeability of the hardened bentonite-cement-wall. In the multi-barrier systems of repositories for chemical or radioactive wastes compacted bentonites are considered to be favourable sealing and backfilling materials because of their high swelling capacity, their adsorption and ion-exchange ability and their plasticity in water saturated state.

Jan 1, 2005

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 M. C. Roberts

The success of any industrial mineral project requires an accurate forecast of the demand for the material. This paper develops a general method of evaluating these needs and applies it to the case of graphite. The basic method is to explain graphite consumption in each of its major uses by the output and manufacturing technology of the using industry. Once these underlying factors are determined, they can be projected to establish future requirements. This demand forecast is critical to the evaluation of a new source of supply, such as the graphite resources of upper Michigan.

Jan 1, 1989

By Sizhe Tan

An open pit mining operation can be considered as a production system with at least two products: ore and overburden (waste). A primary mine planning task is to schedule the production of ore and waste over its life span subject to several technical and economic constraints to maximize some objective such as the overall profit from the operation. Two major constraints are (i) the feasible combinations of ore and waste productions and (ii) the limiting function for ore production as a function of mine life. The task in scheduling production and stripping ratio (ratio of waste to ore production) is to find an ore production curve below the upper bound function of ore production, and a stripping ratio curve within the feasible domain of ore production and overburden removal while maximizing the defined objective. Zn this paper, feasibility of developing computerized optimization models to perform such a scheduling process is explored. Two optimization models are proposed for the task. In the first approach, a linear programming (LP) model is employed and in the second, a dynamic programming procedure (DP) is outlined. In these models, in addition to the consideration of the two major constraints mentioned earlier, various other contributing factors such as interest rate, equipment purchase cost and installation schedule, operating cost, and equipment idle cost are incorporated. An example is provided to illustrate the LP model application.

Jan 1, 1992

By Anthony Harding, Rodolfo D. Aradas, Juan M. Fernandez, Darío Tsingas

"The adoption of tunneled combined sewerage interceptors and outfalls leads to design linings which are often subject to internal pressures that are larger than the external pressures, resulting in significant tension loads. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining. However, improvements in concrete technology and the need to seek efficiency in terms of time and costs, have driven designers to consider single pass segmental linings. The Riachuelo Sanitation project in Buenos Aires is subject to these constraints both upstream and downstream of a sewage treatment plant. This paper describes how the challenges of up to 2 bar pressure differential have been addressed by careful analysis of soil structure interaction to ensure that the full benefit of external ground pressure is realized, resulting in a more optimal design for the constructor both in terms of cost and time. INTRODUCTION The construction of long sewerage interceptors and outfalls is becoming an increasingly common piece of infrastructure for modern urban cities facing a large water front and estuarine conditions, which are under a significant environmental burden imposed by decades of sustained growth. Such works intercept most of the distributed sewage discharges to then divert them to a central treatment point from which it will be finally diffused via an outfall into a water body capable to accept these discharges under acceptable environmental conditions. Depending on the magnitude of the sewage load to be handled, the configuration of the urban environment and the conditions of the receiving water body, both in terms of oceanography forces and seabed conditions, these schemes will vary in length, conveyance capacity and design and construction requirements. When conditions permit, the current trend is the execution of long outfalls using flexible solutions (such as the use of HDPE pipes) which usually require some form of concrete ballasted weights to resist off shore dynamic forces when directly laid over the sea bed. However, this concept faces limitations when the conveyance requirements indicate the need for large diameters (typically above 3000 m) and also when the outfall needs to avoid deep features off shore such as navigation channels. When this occurs, tunneling, particularly segmentally lined tunnel constructed by TBM emerges as the most feasible approach for large diameter, long deep outfalls. The operating conditions often result in internal pressures that are larger than the external pressures, resulting in significant tension loads in the lining. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining."

Jan 1, 2016

By E. Topuz, M. J. McPherson, I. M. Konduri

This paper describes experiments conducted to evaluate the effectiveness of jet fans for ventilating blind headings in under- ground mines. A laboratory model of a mine heading was built by using dynamic similarity criteria, and water as the fluid medium. In order to verify laboratory test results, field experiments were designed and carried out in a full scale mine model and in a coal mine in West Virginia. Using CO, as the tracer gas and in combination with a computerized gas monitoring system, tests were conducted to evaluate jet fan performance. The results highlight the flexibility and versatility of jet fans for ventilating blind headings. Numerical modeling of a jet fan in a typical coal mine heading was carried out to evaluate the potential of computational fluid dynamics.

Jan 1, 1997

By J. G. Groppo, T. L. Robl, C. J. McCormick, W. M. Lewis

The combination of froth flotation and hydraulic classification can facilitate the production of a high-quality pozzolan that meets or exceeds ASTM specifications. This combination has been rigorously evaluated and results of pilot-scale testing are presented. Pilot-scale testing was conducted on fly ash from two active electric utility storage ponds. The tests demonstrated that a high-quality and consistent pozzolan could be produced using Advanced Pozzolan Technologies' Fast Float™ Process. Along with the pozzolan, the additional production of aggregate for masonry mortar and the production of a low sulfur, medium-Btu fuel were also demonstrated. The Fast Float™ Process incorporates several simple unit processes to ensure pozzolan consistency. Classification controls the particle size distribution, which is critical for achieving early strength;flotation controls the grade with respect to L.O.I.; and dewatering controls the moisture content.

Jan 1, 2000