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By C. W. Hunt

I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 1, 1988

By D. H. Carlson, J. H. Johnson, C. F. Renders

Introduction Diesel-powered vehicles are used extensively in underground mines throughout North America. The bulk of the diesel vehicles found in underground mining operations are used for loading and ore haulage, as well as for transportation of personnel and supplies. Along with the advantages of using diesels underground is the disadvantage associated with diesel-tailpipe particulate-matter emissions (DPM). The concentration of DPM in the ambient air of US underground metal mines is not now regulated by the Federal Mine Safety and Health Administration (MSHA). However, recent studies have shown DPM to be mutagenic (National Institute of Occupational Safety and Health, 1988), and the American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that the exposures of per¬sonnel to DPM be limited to an 8-hr time-weighted average concentration (threshold limit value or TLV) of 0.15 mg/m3 (Anon., 1995). The authors, while making measurements in a number of US underground mines that use diesel haulage equipment, found mine air DPM concentrations ranging from 0.2 to 2.36 Mg/M3 (McCawley and Cocalis, 1986; Watts et al., 1989; Cantrell et al., 1991; Haney, 1992; US Bureau of Mines, 1992; Watts, 1992; Watts et al., 1995). If the proposed DPM TLV were to be adopted as a permissible exposure limit (PEL) for US underground mines, the proposed limit of 0.15 mg/m3 PEL would be lower than any of the concentrations measured in the earlier studies and would represent more than a 15-fold reduction from the maximum 2.36 mg/m3 concentration. A 0.15 mg/m3 PEL would also represent a 4.5-fold reduction from the average 0.68 mg/m3 measured mine ambient air DPM concentration reported in this paper. Other diesel tailpipe emissions that are now regulated underground include carbon monoxide (CO), with a PEL of 50 ppm; nitrogen dioxide (NO,), with a PEL of 5 ppm; nitric oxide (NO), with a PEL of 25 ppm; and sulfur dioxide (SO,) with a PEL of 5 ppm. Because the concentrations of these gaseous pollutants and DPM are affected by the state-of-maintenance (Waytulonis,1992), it is important that a means be developed to measure emissions from engines that are now in service to determine when maintenance is needed. The current study was the result of an inquiry by mine¬maintenance personnel who had been receiving complaints about high concentrations of diesel soot (DPM) in mine headings from load-haul-dump (LHD) vehicle operators. Mine-maintenance personnel were searching for an objective test to determine if the diesel tailpipe particulate emitted was excessive. The mine was also evaluating electronically controlled, two-cycle, naturally aspirated, direct-injection diesel engines on some of their JCI (John-Clark Inc.) load-haul-dump (LHD) vehicles. These LHD vehicles were used to haul freshly blasted ore from mine headings to a feeder breaker. The feeder breaker breaks down the larger chunks and feeds the broken ore onto a conveyor. Michigan Technological University, in past studies, developed an emissions-measurement apparatus (EMA) ca¬pable of measuring diesel vehicle tailpipe pollutant concentrations (Chan et al., 1992; Chan et al., 1993; Carlson et al., 1994). At the time of the study reported here, most of the mine's LHD vehicles used a 12-cylinder, four-cycle, naturally aspirated prechamber diesel engine. The study was undertaken in cooperation with mine maintenance supervisors from late 1992 through July 1993. The objectives were to compare diesel exhaust emissions between the 6-cylinder, two-cycle, electronically controlled, direct-injected diesel engine and the 12-cylinder, four-cycle, prechamber diesel engine and to, then, use the data collected, in conjunction with mine ambient air measurements, to demonstrate the application of the "deterioration factor" (Chan et al., 1992), which is a measure of the state-of-maintenance of mine-vehicle engines that are now in service. The information would be used to identify vehicles that need maintenance to reduce emissions. The data reported here are unique in the sense that they combine underground diesel vehicle ambient and tailpipe

Jan 1, 1999

By Volkan Arslan

This study aimed to remove the contaminants in quartz sand by using an eco-friendly method and to obtain high-purity quartz. For this purpose, ultrasound-assisted acid leaching was applied. Equal amounts of a mixture of diluted hydrochloric and oxalic acids were used as the solvent. Response surface methodology (RSM) was used for optimizing, modeling, and predicting the experimental parameters. The correlation coefficient ( R2) of the proposed quadratic model for the relationship between iron removal yield and test parameters was calculated as 0.9731 and it was determined that the predicted and actual values were compatible. Finally, optimization experiments were made and optimum experiment conditions were revised and determined as 83.38 °C of leaching temperature, 196.35 min of leaching time, 2.86 M of acid concentration, and 202.24 W of ultrasound power. Under the optimum conditions determined after optimization, the highest yield of iron removal was determined as 95.08%. Under the optimal parameters, the SiO2 content of the concentrates increased from 97.841 to 99.907% and the Fe2O3 content reduced from 0.225 to 0.011%.

Jul 12, 2021

By J. Noll, E. Cauda, T. Barone, S. Vanderslice

Measuring diesel particulate matter (DPM) for underground metal/nonmetal mine compliance samples is done by collecting DPM onto quartz fiber filters and analyzing the samples via NIOSH method 5040 for elemental carbon (EC) and total carbon (TC). As part of the sampling train, two quartz fiber filters in tandem are housed inside an SKC DPM cassette that includes an impactor. The impactor segregates DPM and mine dust, and the second filter is used to correct for adsorption of vapor phase organic carbon (OC). Since the value of the second filter is subtracted from the first, the pre-existing carbon on the filter media for both filters needs to be comparable. In addition, the pre-existing carbon on the media should be low for accurate and sensitive results. However, there have been some reports of elevated OC on the filter media of the SKC DPM cassettes, which would cause the limit of detection (LOD) to be higher than reported at times. In this study, blank SKC DPM cassettes from different batches and with different expiration dates were analyzed to quantify the amount of carbon on the filter media and to determine the LOD and limit of quantification (LOQ) associated with these samplers. It was found that the organic carbon and total carbon on the media was about five times higher than quartz media used in samplers from other studies. The average TC on the blanks was 2.57 μg/cm2 with a standard deviation of 0.70, resulting in a LOD of 21 μg/m3 TC, 8-hr Time Weighted Average (TWA), and LOQ of 69 μg/m3 TC, 8-hr TWA, when using these samplers for collecting DPM. The LOD and LOQ may be improved through some sample preparation techniques. INTRODUCTION Exposure to diesel exhaust (DE) is associated with an increased risk for lung cancer and other adverse health effects (Attfield et al. 2012, Silverman et al. 2012, Ping and Guang 2017, IARC 2012). Pronk et al. 2009 reported that the highest exposed groups to elemental carbon (EC) from DE worked in underground sites in mining and construction and they were exposed to concentrations between 27–658 μg/m3. At concentrations (1–25 μg/m3 EC) well below those observed in mining, diesel particulate matter (DPM) exposures were estimated to increase the risk of cancer by levels exceeding those typically acceptable for occupational risk in the United States and Europe (Vermeulen et al. 2014). This suggests that underground miners are especially at risk because of their more substantial exposures in confined working spaces. As a protective measure, in 2001, the Mine Safety and Health Administration (MSHA) promulgated a rule to limit exposures of metal/nonmetal underground miners to DPM to an 8-hr time-weighted average (TWA) of 160 μg/m3 total carbon (TC) (MSHA 2001, 2006).

Jan 1, 2019

By B. H. Gardner, S. Serata, D. Dickie

Since 1958, the Sifto Salt Division of Domtar, Inc., has operated the Goderich (Ontario) salt mine in Michigan basin bedded halite, with shafts located on Lake Huron's eastern bank. Initial mining utilized a conventional room and pi1lar pattern. However, roof deterioration developed. Incidence of progressive upward failure of saltback and over1yings ha1ey-do1omite layers intensified with entry aging. Studies were therefore initiated on new mining patterns utilizing the Serata Stress Control Method. Pursuant thereto, three test areas, indicated in the mine plan of Fig. 1, were designed and excavated. Full conversion to Stress Control mining was effected in January, 1983. This paper focusses on the instrumentation work in the third test area. Test Area 3 was designed to validate the excavation geometry of the new stress-controlled main entry system. The testing of that design was accomplished, in part, by comprehensive in situ stress, property, and deformation measurements on the performance of the model main entry section of Test Area 3. The paper describes: (1) the theoretical background of the SPDR/Stress Control Method; (2) specific problems and objectives addressed by the 1983 program of in situ measurements, (3) measurement results; and (4) conclusions drawn therefrom.

Jan 1, 1986

By Jodi Banta

Thanks to strong industry support and longstanding partnerships, the University of Arizona has provided extensive pre-college mining education and outreach for more than a decade. These efforts to promote mining-related degree programs and the wide variety of indemand career opportunities reach thousands of middle and high school students and hundreds of teachers every year. The School of Mining Engineering & Mineral Resources is constantly looking at ways to help students overcome barriers into degree programs. But competition among degree programs for talent is fierce, and outreach has not made a big enough difference in the number of students pursuing mining engineering degrees. With workforce shortages threatening to undermine the industry, more is needed. The Bureau of Labor Statistics estimates 500 new mining engineering jobs each year, and according to a study by Deloitte (2023) nearly 50 percent of skilled engineers will reach retirement age in the next decade. At the same time, the 14 accredited mining or mineral engineering degree programs in the United States are producing fewer than 200 graduates annually (Society of Mining Professors and Society for Mining, Metallurgy & Exploration, 2021). To better understand mining’s competitive position, the School of Mining Engineering & Mineral Resources conducted a comprehensive study to determine (1) how prospective college students, parents and educators perceive the industry, related careers and the mining engineering degree, (2) factors affecting students’ choices of degrees and career plans and (3) the roles parents and educators play and how they influence students. This article is the first of two installments to discuss the results. This installment focuses on what students, parents and educators think about mining and where they get those impressions, as well as the role parents and educators play in influencing students’ choices of careers and degrees. The second installment, scheduled for publication in a later issue of Mining Engineering, looks at what students are seeking in their degrees and careers, and how mining compares with other degrees and industries.

Sep 1, 2025

By C. E. Seaman, H. Jiang, S. Klima, T. W. Beck, Y. Zheng

Respirable coal dust has been long recognized as a leading cause of multiple lung diseases. Efforts aimed at reducing dust concentration in underground mines have been made, but increases in coal workers’ pneumoconiosis incidence rates over the last 20 years among U.S. miners are concerning. Dust deposition and water spray suppression are two types of dust removal mechanisms in underground mining activities. In this study, laboratory tests were conducted to investigate the respirable dust decay characteristics during deposition and suppression processes in a confined dust chamber. Dust concentration and size distribution were monitored continuously throughout each 60-minute test. A number-basis particle size distribution was used for analysis to capture the changes of smaller size fractions within the investigated dust sample. This study found that around 62.1% of respirable dust particles were deposited at the end of the deposition test. In addition, the final deposition rate for very fine particles can be less than 20%. The results from the suppression test indicate that larger particles were removed quickly; however, sub-micron particles remain suspended through the 60- minute water spray, and particles under 0.5 µm can be considered irremovable dust under single-spray operation conditions. This study also observed the resuspension of a significant amount of sub-micron particles by the water spray. The results of this study provide basic information for improving dust control strategies and can be utilized to improve the water spray performance for reducing airborne dust levels.

Mar 2, 2022

By Matthew E. Fowler, Jean Habimana, Roy F. Cook

The West Side CSO Tunnel, Pump Station & Pipeline Project is currently beginning construction along the downtown waterfront of Portland, Oregon. This4.3 meter diameter, 5,500 meter-long soft ground tunnel will be driven along the westbank of the Willamette River adjacent to buildings and utilities and several major pile-supported bridges. High groundwater pressure, extended lengths of gravel to cobble-size alluvium, and the need to control ground loss and surface settlements were key considerations in the selection of slurry tunnel boring machines for the project This paper presents an overview of the numerical modeling that was performed during design to estimate the strains and additional loads in the pile-supported structures and to assess the efficiency of proposed mitigation measures.

Jan 1, 2003

By A. M. El Shafey, Ahmed W. Hussein, Ibrahim M. Gaafar, Mona M. Fawzy, Mohamed Diab, Mohamed S. Abu El Ghar

The Quaternary stream sediments of the Diit area, southern Red Sea coast, Egypt, were mineralogically studied for their content of economic heavy minerals. The study area covered approximately 450 km2 and included three main parts: Wadi and Delta Diit, as well as Diit lens. The mineralogical investigation revealed that these sediments contain considerable amounts of placer ilmenite, magnetite, zircon, sphene, apatite, garnet, and rutile. Also present, in minor or trace amounts, are uranothorite, monazite, xenotime, fergusonite, khatyrkite, and gold. The magnetic fractionation tests, supplemented with the XRD and SEM mineral analyses, indicated the presence of Fe-oxide minerals as wuestite, hematite, and maghemite accompanied with magnetite as products for hand magnet separation. Ilmenite separation was carried out using a high intensity magnetic separator at a current of 1 A, while the paramagnetic minerals (e.g., garnet, pyroxene, amphibole, epidote, monazite, xenotime, and fergusonite) were separated as magnetic fraction at a current of 3 A. The non-magnetic minerals (e.g., zircon, apatite and rutile, uranophane, uranothorite, gold, and khatyrkite) were obtained at 3 A current. On a mineralogical and geochemical basis, the present work suggests that Diit stream sediments should be considered as a potential source for Ti, Fe, Zr, Zn, and Cu after the physical upgrading processes for concentrating the minerals carrying the aforementioned economic elements.

Jan 21, 2022

By Zengwu Zhao, Peng Xu, Jieliang Wang, Qingwei Bai, Xinyang Liu, Xiao Lei

The paper investigates the capture and recovery of rare earth minerals from Bayan Obo ore using superconducting magnetic separation. A finite element model (FEM) was established to study the influence of various factors on the capture of rare earth minerals under a high-gradient superconducting magnetic field. The study aims to improve the efficiency of rare earth mineral separation and recovery.

Oct 1, 2023

By Steven J. Schatzel, Mark M. Mazzella, Robert A. Kimutis, VASU GANGRADE, James D. Addis, Marcia L. Harris, Mayley Guitard

Researchers from the National Institute for Occupational Safety and Health (NIOSH) evaluated the impact of potential shale gas well breaches and subsequent gas inflow on selected mine ventilation systems of operating longwall panels using a 1:30 scaled Longwall Instrumented Aerodynamic Model (LIAM) and Sulfur hexafluoride (SF6) as a tracer gas. A series of tests were performed at 340, 400, and 500 cfm inflow levels utilizing different mine ventilation scenarios. Results suggest that the breached gas can be diluted to meet statutory levels when the longwall panel is adequately ventilated. The results enhance the understanding of the gas inflow and mine ventilation system interaction and provide critical information to the industry and regulatory agencies for improving miners’ safety.

Feb 1, 2024

By Alfredo Valencia-Toledo

This study delves into the satisfaction levels of indigenous communities in Apurimac-Cusco, Peru, concerning mining activities in their region. Our primary objective is to elucidate the interrelationships among observable variables, which are conceived as linear combinations of multiple factors. Employing the statistical methodology of exploratory factor analysis, we aim to pinpoint the pivotal factors influencing the progress of mining activities in Apurimac-Cusco. Through our analysis, we have identified eight key factors that exert a significant impact on mining’s sustainable development in the area. These factors encompass diverse facets, ranging from the support offered by mining company to communities, environmental considerations, education, economic factors, provision of basic services, transportation and communication, support for social organizations, and social-health-related aspects. This research endeavors to provide a comprehensive understanding of the complex dynamics surrounding mining activity satisfaction among the indigenous population, offering a basis for further exploration and policy development.

Feb 17, 2024

By Rex C. Bryan

An accurate and dependable ore reserve estimate is important to any mining company. It is also essential for development drilling and production planning to know about the distribution of the ore within the area to be mined. This paper will show that in the case of more variable deposits such as uranium, the use of geostatistics is superior to conventional techniques. Unlike conventional methods, geostatistics includes the importance of spatial orientation of measured variables. With the use of variograms in conjunction with kriging, a point or a block may be estimated along with its error of estimation. The existence of disequilibrium can create a severe problem in uranium 'ore reserve estimation, and mine and production planning. Disequilibrium can be simply defined as the ratio of chemical or assay values to gamma equivalent values calculated from the downhole geophysical gamma-ray logs. Various methods for adjusting for disequilibrium have been proposed. Most, however, have side stepped the consideration of disequilibrium itself being a regionalized phenomena; or its, relation to surrounding geology. This paper presents methods of incorporating both aspects. The East Dilts Pit at the Bear Creek Uranium Mine in Wyoming, has been used as a case study. Polygonal, triangular, and lognormal kriging and various disequilibrium adjusted methods, including multi-factor cokriging have been com- pared with the mining experience.

Jan 1, 1982

By Carlo Grandori

Foreword In loose ground and soft rock formations, mechanical tunnel boring is necessarily dependent on the adoption of shield machines and the application of adequate support or lining structures. These structures are erected either within or immediately behind the rear portion of the shield and provide the required reaction to the forward thrust. In competent rock formations where systematic support is not a requirement, hard rock tunnel boring machines generally advance by thrusting from a structure gripped against the tunnel walls. These machines may feature a more or less extended cutterhead shield or roof support, but when in weathered, fractured or otherwise weakened ground, or in fault zones filled with soft gouge, the gripper mechanism often cannot provide enough thrust reaction to advance the cutterhead. Under these conditions, early support of the arch and walls is generally required in the form of rock bolts, steel rings and laggings and some times of a primary concrete lining placed in the short section between cutterhead and grippers. Such tunnel support measures generally fail to produce an adequate increase in thrust reaction capacity, but

Jan 1, 1976

By James A. Curry

Table I identifies the maximum cost of the individual provisions with spoil disposal in Appalachia leading at $3.98 per ton, This was followed by deep mine subsidence control and monitoring at $1.66 per ton. At the request of the U.S. Department of Energy, the Bowser-Morner Testing Laboratories of Dayton, Ohio, evaluated Consol's cost estimates for 14 of the 21 regulatory provisions the company studied. It is interesting to note that Bowser-Morner concluded that Consol's estimates of costs were very conservative and that the actual costs will be substantially higher than what the company reported. In 1978 a joint committee of the National Coal Association and the American Mining Congress made estimates of cost impacts under 11 OSM permanent rules (see Table II). Six rules applied to mid-western strip mining were projected to cost $6.52 to $17.17 per ton. Five rules applied to mid-western strip mines showed costs ranging from $.91 to $6.11 per ton. Three rules applied to deep mines (regardless of region) were seen raising costs from $ .57 to $2.67 per ton. The joint committee reported trouble developing overall figures because member firms used widely different assumptions in calculating their costs. That same statement could no doubt be made when comparing most cost data available today.

Jan 1, 1980

By Raj K. Singhal

This paper is a report on a task force study dealing with many facets of computerization. The primary mandate of the task force was to examine the software and hardware currently available for application relating to reserve estimation, mine planning, economic evaluation, equipment selection, production scheduling and composite mine simulation and to evaluate how adequately the software fulfills the user needs in surface mining of oil sands and coal. To meet its objectives the task force consulted extensively with the users, developers and suppliers of hardware and software. The paper outlines the approach taken by the task force to fulfill its mandate, summarizes its findings and presents some pointers which might be useful to others considering this type of evaluation.

Jan 1, 1986

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

By A. Chamaret

Minerals extraction is related to complex sustainable development issues that are subject to international and local controversies. Debates must be based on objective and comparative elements. Defining strong indicators for assessing impacts and performances of mining sites thus appears necessary to inform and support the decision-making process for stakeholders. Recently, many indicator sets have been developed on an international level based on top-down approaches, but they commonly lack legitimacy for stakeholders and adequacy to specific site issues. They thus need to be complemented by the consultation of local actors concerned by such mining activity, in order to define indicators that are closer to the needs and contexts of the specific sites. The question raised by this kind of top-down/bottom-up approach is how to organize and reveal the plurality of values and concerns associated with mining. Based on the principle of representative diversity, the approach undertaken at the Arlit uranium mines in Niger aimed at defining indicators that are understood and accepted by all actors. The aim was to measure the impacts and performances of mining sites in the four sustainable development dimensions, and at local, regional and national scales.

Jan 1, 2007

By ERIK CHARRIER, HUGH MILLER, JOSEF BOURGEOIS

In this study, a unique excavation system was characterized, utilizing waterjet technology as the primary tool for material removal during rehabilitation of reinforced concrete and shotcrete structural liners. Through empiric testing, this research seeks to validate the hypothesis that waterjet removal of these support systems will result in less unintended damage than conventional removal methods. The intent is to develop a viable technology that will reduce the collateral damage caused to surrounding liners during excavation, improve the adhesion between shotcrete and the substrate for longer lasting ground support, and improve overall safety for workers in underground environments. An analysis on the fracture mechanisms and operating parameters of each method was completed. Instrumented shotcrete panels were physically tested and examined through visual inspection and ground penetrating radar (GPR) to compare substrate damage according to each testing method. After testing was completed, the data strongly indicates that waterjet cutting causes less collateral damage to the surrounding intact liner and substrate when compared to that of conventional impact hammers. This research is intended to provide a scientific basis for additional applied research in the rapid excavation and repair of shotcrete support systems.

Sep 23, 2021

By Juan L. Yarmuch, Gonzalo Sepulveda

Medium- and short-term mine planning holds immense significance in optimizing production and resource utilization. It serves as a vital link between the long-term strategic plans and the day-to-day operational activities of a mine. In this context, a mathematical formulation is proposed to incorporate mining width constraints into the production scheduling process, aiming to maximize the net present value (NPV) of the schedule while ensuring enough room for the operation of mining equipment.

Jul 1, 2024