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By Fengmei Chen, Na Liu, Bingrui Li

A quantitative analysis method based on the airflow influence factors is proposed to evaluate airflow stability and discriminate airflow directions in complex ventilation networks. The law governing the changes in airflow caused by changes in branch resistance is revealed based on simulations of the airflow state in a ventilation network and a statistical analysis of the results. Then, three evaluation indices (airflow sensitivity, airflow influence factor, and critical airflow) are determined, matrices of the airflow influence factors and critical airflows are constructed, and a quantitative evaluation method for ventilation system stability and an airflow directional discriminant are proposed. The results show that the stability of a ventilation system can be reliably evaluated based on the airflow influence factors. The sensitive branches and dominant branches in the ventilation network can be determined based on the matrix of airflow influence factors, and the reversed branches, the trigger branches, and the reversal conditions can be determined based on the critical airflow matrix and the matrix of airflow influence factors. The proposed airflow directional discriminant is suitable for evaluating arbitrarily complex networks.

Nov 15, 2023

By S. C. Sethi

The WIPP (Waste Isolation Pilot Plant) Project near Carlsbad, New Mexico, is a research and development project sponsored by U.S. Department of Energy, designed to demonstrate the safe containment for disposal of radioactive waste. A mine (repository) is currently being developed 2150 feet below the surface, in a thick salt bed which will serve as the disposal medium. Provision of a proper ventilation system at the WIPP Project is a major priority of those responsible for its design, management, and operations. As an ongoing effort towards this goal, it was decided to simulate the mine's ventilation system using Dravo's MINEVENT computer program. Specifically, the work included the development of the following simulation models: 1. Simulation of the current ventilation system 2. Simulation of the designed ventilation system for the following modes: o Mine Construction mode/shift o Waste storage mode/shift o Fire or exhaust filtration mode These computer models are useful in solving complex ventilation problems likely to be encountered in an R&D project, like WIPP. They are particularly helpful for the development of contingency plans to incorporate during emergency situations, such as fires, fan stop- pages, radiation leaks, etc. Also, they can be utilized when considering expanding certain underground areas to ensure the availability of adequate ventilation.

Jan 1, 1986

By Haydn H. Murray

The area from Ohio on the east, Tennessee on the south, and Minnesota on the west: contains some very unique and useful clay deposits. Included are fireclays and plastic clays in Ohio, Kentucky, Indiana, Illinois, and Missouri; flint clays in Kentucky and Missouri; ball clays in Kentuckv and Tennessee; adsorbent clays (fuller's earth) in Missouri, southern Illinois, and Tennessee; and alluvial clays and shales for structural clay products from every state. Unique kaolin clays are known in Minnesota, Missouri, and southern Illinois and halloy-site localities are known in southern Indiana. The geology, physical properties, and uses or potential uses of these midwestern clays are described.

Jan 1, 1980

By S. W. Cavender

The analysis of the results of metallurgical experiments is often complicated by experimental errors and uncertainty, the complexity of the system being studied, and the confusion of correlation with causation. Consequently, comparative statistics are used to determine if a difference exists between the outcomes of tests, an estimate of this difference, and the precision of the estimate. This paper reviews the use of significance tests and confidence intervals for the comparison of results from two tests, the use of reference distributions, and blocking and randomization techniques to reduce unavoidable sources of variability. These techniques are demonstrated using plant and laboratory data.

Jan 1, 1993

By E. C. Watkins

The fiber glass industry is an industry that. hopefully is still in its infancy and far from a mature business. Fiber glass, as will be discussed in this paper, deals with continuous strand glass as used in the textile laminate and reinforced plastics industries. More specifically, we are speaking of glass used for printed circuit boards, tapes, paper, cloth, pipes, tanks, boats, recreational equipment, roofing shingles, and automotive applications. Compared to the flat, container and decorative glass industries, we are very young. The early patents on fiber glass applications were issued in the 1930's. The type of glass most commonly used in the world and that discussed in this paper is designated as "E" glass. This is a boro-silicate type glass having specific chemical and electrical resistance and low thermal expansion properties.

Jan 1, 1986

By Xinming Chen, Huazhe Jiao, Qi Zhang, Yunfei Wang, Liuhua Yang

The effect of initial damage generated by weakly cemented interlayer surfaces on the physico-mechanical properties of layered cemented tailings backfill (LCTB) is considered for the interlayer inclination structure generated by multiple layered backfills in large-scale mining voids. Utilizing the theory of damage mechanics, the damage evolution and constitutive model of LCTB with interlayer inclination is constructed by considering the coupling of interlayer inclination effect and loading. Based on Mitchell’s mechanical model, we analyze the damage mechanism of the inclined cementation surface of LCTB, and derive the expression for the strength of LCTB considering interlayer inclination. The mechanical properties test of LCTB with different inclinations was carried out, and the results showed that the damage model of LCTB established was highly consistent with the experimental curves, which verified the correctness of the model. The initial inclination damage leads to the decrease of adhesive cohesion of cemented surface, and with the increase of inclination, the separation of layered surface, aggravation of misalignment, layered cemented surface is more prone to shear damage, and the mechanical properties of cemented tailings backfill in the lower part of layered surface are not effectively played, which reduces the overall performance of the material.

Nov 23, 2023

By W. D. Hausel

The Wyoming craton in the western United States is a favorable terrane for diamond deposits. The craton hosts a variety of ultramafic, ultrabasic, and ultrapotassic rocks. Additionally, a few hundred 'kimberlitic' heavy mineral anomalies and some geophysical and remote sensing anomalies indicate the presence of undiscovered, mantle-derived, pipes in the craton. The Wyoming craton is separated into a Wyoming 'archon' known as the Wyoming Province, and the Colorado 'proton' known as the Colorado Province. The 'archon' underlies much of Montana and Wyoming and continues north into Alberta and Saskatchewan; the Colorado 'proton' underlies much of Colorado and a small portion of Wyoming. Although most exploration geologists would consider the 'archon' the most favorable terrane for commercial diamond deposits, the 'proton' has produced more than 120,000 diamonds, while the 'archon' has not been very productive.

Jan 1, 1996

By Sunfangze Liu, Xumeng Chen, Yongjun Peng

Efficient separation of naturally hydrophobic gangue, such as talc and carbonaceous materials, from sulphide minerals in flotation is becoming a significant challenge in many processing plants due to the need to process lower grade and more complex ores. Considering the hydrophobic nature of these gangue minerals, prefloating them at the beginning of the flotation circuit in the absence of collectors and rejecting the concentrate is a common practice to remove these gangue minerals. However, sulphide minerals, such as chalcopyrite, can become naturally floatable due to surface oxidation and therefore may float together with naturally hydrophobic gangue. In this study, a new approach was developed to maximize the prefloat of hydrophobic gangue while minimizing the loss of sulphide minerals. The new approach introduced a prefloat cleaner stage where sulphide minerals recovered to the prefloat concentrate was depressed and separated from other hydrophobic gangue minerals at a low pulp potential with the prefloat cleaner tailing fed back to the main sulphide flotation circuit. Flotation tests were conducted using chalcopyrite and organic carbon. The results show that the proposed approach can significantly reduce the loss of valuable minerals in the prefloat flotation without affecting the reject of naturally hydrophobic gangue. Applying pulp potential control at the prefloat cleaner flotation stage also reduces the consumption of reducing agents while minimizing the effect of reducing agents on downstream rougher flotation.

Nov 23, 2020

By Thomas B. Dellinger

Since 1950, rotary-drilled, large-diameter holes, "big holes", with depths to over 300 feet and diameters of over 30 inches have become numerous and widespread. Fifty such holes have been drilled for access shafts to LPG mined caverns, Over 70 holes have been drilled for various other commercial activities. Over 150 holes have been drilled by the AEC for atomic testing purposes. These holes have ranged up to 300-inch diameters with 1600-foot depths, 120-inch diameters with 570-foot depths, and 72-inch diameters with 4800-foot depths. Equipment is now available to drill a wide range of ?big holes? for varied requirements. At least a dozen drilling contractors are participating or have participated in the drilling of "big holes". The accompanying tables show pertinent historical, technical and economic data on over 250 holes. The illustrations to be presented concurrently with this paper show the various equipment and accessories now in use. (See Appendix I for captions of illustrations.)

Jan 1, 1966

By John B. Gustavson

The mineral deposits found in carbonate facies rocks of sedimentary basins include deposits comprised of the country rock itself such as limestone for chemical uses, dolomite for road aggregate, and a variety of other industrial uses of the sedimentary rock. Exploration for new reserves is generally conducted on basis of outcrop investigation, subsurface drilling, and facies change studies while geophysics and geochemistry are not applied. In contrast, rapid development has taken place in the application of both geophysical and geochemical techniques in exploration for stratiform deposits of zinc, lead, barite, and fluorite deposits. This paper will present case histories and show illustrations from such work in the Mid-Continent region. The Metals Division of International Oil & Gas, Inc. has gathered this experience through work over the last three years along the southern margin of the Eastern Interior platform focusing on the states of Arkansas and Tennessee. The exploration work was conducted partially for the Company's own account, partially in joint exploration ventures with mining companies including International Mogul Mines, Ltd., a Canadian company; Bear Creek Mining Company, a subsidiary of Kennecott Copper Corporation; the Mining Division of W. R. Grace and Company, and Boliden-Preussag Exploration, a Swedish-German partnership. We wish to take this opportunity to thank our venture partners for allowing presentation of the various sections of this paper.

Jan 1, 1976

By J. D. Miller

Many factors -- political, environmental and technological -- will determine the extent to which the United States realizes the potential of its vast coal resources. Not the least of these factors is technogical development including mining, processing and transportation. With regard to processing technology, about 50% of the 800x106 tons of coal mined annually in the U.S. is processed in preparation plants. The purpose of the physical separations accomplished in these preparation plants is to remove ash (present as clays and other oxide minerals) and sulfur 'present mostly as pyrite). Coal flotation circuits for such separations are becoming more important in the processing of minus 28 mesh coal. (1,2,3) For example in the U.S. in 1960, 31 flotation plants processed 26,500 tpd; whereas in 1980, there were 80 flotation plants which processed 78,300 tpd. This corresponds to an annual growth in flotation plant capacity of 10 per year during the past two decades. Coal flotation is based on the natural or induced hydrophobicity of coal particles which are separated from hydrophilic ash and sulfur constituents by attachment to air bubbles. The coal particle/air bubble aggregates are collected in a froth phase which is created by the addition of a suitable frother such as MISC. Without exception, such separations are made in a conventional flotation cell, which, in essence, is a stirred tank reactor with a shrouded rotor to shear the air as it passes through a hollow shaft. The dispersed air bubbles (4.0 mm diameter) are stabilized by addition of the frother. Collision of the air bubbles with, and/or precipitation of the air bubbles on, the coal particles results in the formation of coal particle/air bubble aggregates which rise in the gravitational field and are collected in the froth phase developed at the top of the flotation cell. Restraints on successful separation by this conventional flotation technique are particle size and retention time. Generally it is found that effective flotation is only achieved for particle sizes between 10 and 1000 microns. Further, with respect to retention time, it is found that a nominal retention time of at least 2 minutes is required for successful separations. These facts limit the effectiveness of conventional coal flotation. Coal fines may be lost in the reject stream and disposal is frequently a problem. The retention time required for conventional flotation results in large floor space demands which limit the capacity of the plant.

Jan 1, 1981

By Rodolfo Lagos, Nicos Pfeiffer, Ben Harding, Clayton V. Deutsch

This paper documents a probabilistic resource modeling workflow for the Round Mountain epithermal gold deposit. The set of categorical and continuous variable simulated realizations provides a model of variability and uncertainty given the current orebody knowledge. These realizations can be used to quantify and understand expected deviations in reconciliation during mining and provide a more accurate measure of expected gold than an estimated model. Gold mineralization at Round Mountain is primarily contained within tertiary tuff units, which dip gently to the west and thicken towards the southern part of the orebody. Domain boundaries are modeled as combinations of lithology and alteration; alteration domains are constrained to be within the tuffs. Large-scale geologic uncertainty is strongly influenced by parameter uncertainty, particularly the input histogram. The spatial bootstrap characterizes prior global uncertainty in the input histogram for categorical and continuous variables. Categorical models are generated using hierarchical truncated pluri-Gaussian (HTPG) simulation. Continuous variable simulation is carried out within the simulated domain boundaries using trend models to account for non-stationarity.

Aug 19, 2023

At long last, mining is on the rebound in Minnesota?s Iron Range and the excitement is starting to show. The SME Minnesota Section?s annual meeting was once again held in the heart of Iron Range country, at the Duluth Entertainment and Conference Center on the Duluth waterfront. The conference boasted a record attendance of 475 people and its largest-ever trade show. Appearances by Governor Mark Dayton?s new Iron Range Resources & Rehabilitation Board (IRRRB) appointee, Tony Sertich, as well as a local Fox news crew (see clip on SME website [link: http://fox21online.com/news/duluth-mining-conference-breeds-optimism-tech-innovation]) made clear that a lot of eyes [ ] are on the industry as it dusts itself off from the 2008-2009 recession. While the early years of the 21st century were very good to the Iron Range, the global drop in commodities prices and production left many companies reeling and brought back bad memories of the collapse of the industry in the 1980s. However, two years of solid growth and a rebound to above pre-2008 production levels have let the Minnesota mining industry to relax a little and talk seriously about long-term growth and stability.

Jan 1, 2011

By Miguel Reyes, Chenming Zhou, MATTHEW GIRMAN

Electromagnetic energy emitted from electronic devices has been known to interfere with other electronic systems, hindering their ability to function properly. Mines have many electronic devices critical to the health and safety of mine workers that could be negatively affected by electromagnetic interference (EMI). To ensure that devices are electromagnetically compatible, tests must first be conducted to measure emissions and check for immunity. There are many standards available across multiple industries that prescribe emission limits and test methods for electronic devices. Due to the unique environment of an underground mine, it may not be enough to simply adopt a standard from another industry to mining. A literature review has been conducted, and an overview of EMI standards in other industries will be provided in this paper. Also, an example of how a standard can be applied to mining equipment is presented. Finally, recommendations on standards which could potentially be applied to mining will also be included. This work will inform the mining industry of EMI standards in other industries so that mine workers and technology manufacturers have guidance of the steps that can be taken to investigate and reduce the impact of electromagnetic interference and potentially work toward electromagnetic compatibility. The findings and research involved in this effort can also be used to explore the need to develop mining-specific EMI recommendations and standards.

Nov 25, 2021

By Ali Nazem, Rennie Kaunda, Zoheir Khademian, Fei Wang, Raymond Henn, Alex Peretiatkol

"The field demonstration portion of the Underground Grouting and Ground Improvement (UG&GI) short course offered by the Colorado School of Mines was held on May 18, 2016 at Baski Inc.’s Yard in Denver, CO.Numerous full field scale demonstrations of grouting methods and equipment were conducted under various field conditions. As part of these field tests, permeation grouting testing and demonstrations were also conducted. Various cement grout mixes were injected into 1.5-m (60-in.) tall transparent sand columns under controlled conditions (Fig. 1). The objective of the sand column permeation grouting demonstrations in the study was to show students the effects of ordinary Portland cement versus ultrafine cement on the engineering properties of the grout, and the permeation height through various types of soil stratigraphic layers in the sand columns. Similar previous demonstrations have had a specific focus on various brands of Type I-II Portland cements and ultrafine cements with a range of water cement ratios and injection pressures. More detailed information about these previous studies can be found in published proceedings (e.g. Henn et al., 2009 -2011).Equipment and material usedThe five clear plastic sand columns were 191 mm (7.5 in.) inside diameter and 1,524 mm (60 in.) tall. Each sand column had a 19 mm (0.75 in.) diameter hole drilled at the base (bottom) of the blind flange for injection of the grout. A perforated plate and/or screen at the base of the sand columns helped to prevent sand from plugging injection port. A ChemGrout grout plant was used for the demonstration consisting of 0.36 m3 (97 gal) high shear (colloidal) tank mixer, a 0.36 m3 (97 gal) agitator tank and a progressive helical cavity pump with maximum output capacity of 77 L/min (20 gpm) at a maximum discharge pressure of 265 psi (18 bar) (Fig. 2). A simple grout header arrangement consisting of control valves, pressure gauges, flow meter, grout delivery and return line, and a short injection line was also custom built. Also used were infra-red thermometers to measure the temperatures of the grout mix batches, CRD and marsh funnels to measure viscosity, baroid mud balance to measure specific gravity, and a digital scale to measure weights. The grout materials used were Holkim Portand cement (Type I-II), Nippon Steel Sumikin superfine cement and U.S. grout ultrafine cement."

Mar 1, 2017

By Tedd B. Bodimer

Why complicate an already complex machine such as a continuous miner by adding roof drills? Immediate permanent roof support is an immediate thought of the mining engineer just as elimination of frequent time-consuming places changes is a thought of the methods engineer. The realization of those two objectives has the potential for improved safety with increased production is the thought of the general manager. Miner-Bolters Used a Generation Ago These are not new thoughts as the 1CM continous miner equipped with two integral roof drills was introduced twenty-five years ago. Approximately two hundred of these machines were sold in the next five years for use in medium and high seam operations. The 1CM miner chassis that remained stationary in the center of an entry or room while the ripper bar was swung and sumped hydraulically provided an ideal platform for mounting two roof drills that could be operated during the continuous miner's production cycle. Two roof bolts could normally be installed in less time than required for the mining cycle. A typical roof drill unit is shown in Figure I.

Jan 1, 1981

By Maurice L. Madden

An investigation was undertaken for a ground water discharge plan for the Chino mining complex near Hurley, New Mexico. Operations which impact ground water include dump leaching, storage reservoirs, and tailings seepage. The investigation included both hydrogeological data collection and laboratory analysis. A conceptual understanding of surface water and ground water was then developed. Surface water and ground water models were used to match existing conditions and predict the impact of operational modifications. The study concluded that runoff and resulting leach reservoir overflows were primarily responsible for the ground water degradation. Tailings seepage represents a smaller part of the impact.

Jan 1, 1984

By J. Alatalo

Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore itself as the grinding media. It is a process that is difficult to control and there is a lack of knowledge of the events occurring inside the mill. To find out more about how the mill behaves under different processing conditions, a full factorial test was performed with iron ore in a pilot-scale pebble mill at the LKAB R&D facility in Malmberget. To complement this work, a strain gauge detector was embedded in one of the mill?s rubber lifters, the Metso Minerals continuous charge measurement (CCM) system, and was used to get more information about the charge dynamics. The data from the experiments has been analyzed. For production purposes, an increase in the number of particles smaller than 45 µm can be regarded as a probable increase in the production rate. The analysis shows that there will be an increase in fines at 65% of critical speed, especially when the mill is 45% full. This setting will also increase the power consumption, but improves the grindability of the ore even more. The deflection of the lifters is smaller for lower critical speeds. A higher degree of filling also gives a smaller toe angle and a higher shoulder angle as expected.

Jan 1, 2011

By J. Alatalo

Autogenous grinding is a process of reducing the particle size distribution of an extracted ore by using the ore itself as the grinding media. It is a process that is difficult to control and there is a lack of knowledge of the events occurring inside the mill. To find out more about how the mill behaves under different processing conditions, a full factorial test was performed with iron ore in a pilot-scale pebble mill at the LKAB R&D facility in Malmberget. To complement this work, a strain gauge detector was embedded in one of the mill?s rubber lifters, the Metso Minerals continuous charge measurement (CCM) system, and was used to get more information about the charge dynamics. The data from the experiments has been analyzed. For production purposes, an increase in the number of particles smaller than 45 µm can be regarded as a probable increase in the production rate. The analysis shows that there will be an increase in fines at 65% of critical speed, especially when the mill is 45% full. This setting will also increase the power consumption, but improves the grindability of the ore even more. The deflection of the lifters is smaller for lower critical speeds. A higher degree of filling also gives a smaller toe angle and a higher shoulder angle as expected.

Nov 1, 2011

By J. D. Miller

The recent non-equilibrium electro-phoretic mobility measurements by laser-Doppler electrophoresis coupled with the stability and prevalence of collector colloids in soluble salt flotation systems suggest that the selective flotation of alkali halides is due to the adsorption of oppositely charged collector colloids by hetero-coagulation. Previously reported flotation results confirm this surface charge/collector colloid adsorption model. However, the nature of the inter-particle forces responsible for hetero-coagulation of such oppositely charged particles at high ionic strengths remains to be determined. In this regard, atomic force microscopy was used for inter-particle force measurements at high ionic strengths. Model systems such as polystyrene/quartz and silica/sapphire were studied to measure the particle interaction forces prevalent at high ionic strengths. Results from this study indicate that while repulsive hydration forces exist between similarly charged hydrophilic particles, attractive forces exist between oppositely charged hydrophilic particles in high ionic strength solutions. The repulsive forces between similarly charged hydrophilic surfaces at high ionic strengths (2-4 M) are described by a double exponential function with decay lengths of 0.17 and 1.4 nm depending upon the surfaces involved. On the other hand, attractive forces were observed between oppositely charged hydrophilic surfaces at high ionic strengths (2-4M) and were described by a single exponential function with decay lengths of up to 9 nm depending upon the surfaces involved.

Jan 1, 1996