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By Eleanor Sonley

In October 2000, temporary seismographic stations were installed above the Trail Mountain Mine, Emery County, Utah, USA to supplement a regional network. Over seven months, 1826 mining-induced seismic events were recorded with a magnitude range of M 0 to M 2.2 (Arabasz et al., 2002, 2005). Routine event locations for this dataset cluster around the longwall mining activity during the recording interval. However, applying a double difference relocation technique to the routine locations significantly improves the correlation between mining activity and event location. The resulting relocations depend greatly on station distribution and the number of arrival time picks. We use this dense temporary array to assess station distribution requirements for applying the double difference technique at other mines by systematically removing data from available stations, thus simulating sparser networks. The insight gained using the Trail Mountain dataset is used to develop a metric for assessing the usefulness of above-mine networks and to develop a tool for expanding seismic network coverage. To verify the appropriateness of these tools for wider application, we examine data from two additional mines located in the western United States. Improving the relative locations of mining-induced seismic events highlights the association of these events with active portions of the mine. Clusters, regions of quiescence and relative timing of events can be used by mine operators to assess hazard, optimize production, and evaluate performance of mine plans. The lessons learned from this study may be used in future network design to improve accuracy of event locations at other mines.

Jan 1, 2009

By J. R. Arnold

The problem of recovering gold from a cyanide solution has been plaguing metallurgists since the cyanidation process was discovered in Glasgow, Scotland.1 The "perfect" method has never been found and this paper will not purport to fill that gap. But we, at Gold Fields, feel that we have developed a workable, cheap and efficient method of producing a refinery - ready product that has several distinct advantages over conventional electroplating techniques. The Gold Fields replating system is presently being used at their Ortiz and Mesquite operations. In short, the system electroplates the gold out on stainless steel wool, instead of mild steel wool as is usually done, then replates the gold by reversing the current onto stainless steel plates. By doing this the steel wool can be reused many times, the gold can be scraped off the plates cleanly and quickly, the operating costs are reduced and the slag production is greatly reduced.

Jan 1, 1986

By Renee Royer, Allan Punkkinen

As mines progress to ever increasing depth, new challenges are encountered with serious concerns for rock excavations in highly stressed conditions. New procedures have been undertaken or are under way to remove workers from the workface, mitigating risk and exposure to hazardous conditions. Rockbolting crews are at particular risk as they are the first line of defense in the installation of the ground support systems. One such initiative for removal of workers from danger has been with remote bolting. Equipment manufacturers have had the ability to remotely inject resin pneumatically into boreholes for several years, but it has not been recognized as a very effective method due to a variety of complications. This makes the installation of dynamic support system components such as the D-Bolt® increasingly difficult. More recently, hollow-core bolts have become popular providing far more effective installation when installed with pumpable, two component urea-silicate injection resins. Normet has developed high energy dissipation self-drilling dynamic bolts (SDDB®) to meet these challenges. Following several inquiries as to the effectiveness of pumpable resins for use with dynamic support components, Normet Canada performed comprehensive testing of the bolt and resin system at CanmetMINING in Ottawa to dispel or substantiate any preconceived beliefs. Several dynamic and static tests in direct and indirect loading were carried out. Results include tests in shear and early strength UCS of the resin to measure the performance of the SDDB compared with the established D Bolt as an effective dynamic ground support component. Underground field observations, installation methodology and in-situ testing are investigated.

Apr 26, 2022

By Andre C. Zingano

It is a very difficult task to estimate the immediate roof and support behavior in a room-and-pillar mining section in the initial phase of the mining project. There is little information available at this phase, and it is restricted to geomechanic characterization of the rock layers from cores samples, and the in-situ instrumentation of experimental entries and intersections. Even being a pilot excavation for roof support test a good indicator for the behavior of the immediate roof, its behavior for a full excavation mining section is different from a single intersection of two entries, mainly because the stress redistribution caused by the multiple entries excavation and face advance for a full excavation section. The objective of this paper was to calibrate a 3-D numerical model of an experimental intersection, based on the in-situ instrumentation of an experimental intersection excavation, and the geomechanic description of the rock layers. The numerical model was built with the same specifications as the excavation test, including the entry geometry and roof support. The numerical model calibration was based on wire extensometers that were installed at different positions in the roof of the pilot excavation, and on the geomechanic characterization of the rock layers that form the roof, coal seam, and floor. Therefore, it is possible to estimate whether the roof support specification adopted in the test phase will be good enough for the development of the entire mining section.

Jan 1, 2009

By R. W. Waytulonis

New exhaust control techniques and devices may be necessary to meet future diesel particulate matter emission standards in underground coal mines. This paper reviews conventional work practices and devices used to control diesel exhaust emissions, and new techniques being tested by the Bureau of Mines. Discussions will center on important work practices and on the function and efficiency of exhaust after-treatment devices. An industry/government cooperative research project to develop and test an exhaust after-treatment system for part 36 equipment is also discussed.

Jan 1, 1990

By James L. Hendrix

This paper is intended to give the reader an update on the work being done at the Mackay School of Mines about the fate of cyanide on precious metals mill tailings waste. During the last two years several tailings impoundments have been sampled and analyzed for total and free cyanides. From our sampling program we are beginning to learn valuable information concerning the fate of cyanides in precious metals mill wastes. Included in this paper is a detailed description of our sampling and analytical techniques. Also, some of the data obtained from five sites are given.

Jan 1, 1986

By Fulvio V. Fonseca

The Trombetas bauxite deposits were discovered by ALLAN, as from the original work of the geologists Drs. E. E. GREIG and 3.A. STAARGAARD on the axis of the Amazon river, between Manaus and Santarem - (see fig. 1). With research licences obtained in 1965 by the SANTA RITA BAUXITA - a subsidiary of ALAN a group of Brazilian geologists, under the supervision of IGOR MOUSASTICOUSHVILLY, begins researches on the areas of Parintins, Juruti and Mathias with unsatisfactory results. In 1966, photographs obtained from the US Air Force and the Brazilian Oil Company PETROBRAS -, covering an Amazon region between Parintins, Santarem and north of Trombetas river, permitted the identification of a great number of plateaux between the Nhamunda and the Trombetas rivers. Based on this information, a research group has worked intensively from 1966 to 1967 allowing the discovery of the trihydrated bauxite in a quite large area. After five years of intense work and analysis of approximately 56.000 samples, near 500 million of tonnes of bauxite are evaluated on the several plateaux of the, area, thus insuring the commercial exploration of these deposits. Such discovery places Brazil among the detainers of the main bauxite stocks of the world and as a potential exporter.

Jan 1, 1980

By Morgan M. Sears, Gamal Rashed, Michael M. Murphy, Brent Slaker

A parametric study was conducted using FLAC3D numerical models to examine the impact of oblique loading on the strength and yield pattern of a stone pillar using two simplified geometry types. In type-1 the side walls of the pillars were assumed to be perpendicular to the roof and the floor, while in type-2 the side walls were assumed to be vertical. These two geometries are frequently used to simplify/model the creation of pillars in dipping mines. Results from the numerical modeling indicate that dipping pillars have reduced strength compared to horizontal pillars, and they are at an elevated risk of failure. Also, an asymmetric failure propagation pattern could be obtained depending on the interaction between the pillar width/height (W/H) ratio, seam dip, in situ stresses and pillar geometry.

By Rodney R. Krause

In attempting to tell the general public about the coal industry's land reclamation efforts, we have often said, "We're not doing things by the book, because we're still writing it." Like any good catchphrase, the statement is not only striking but true. It is particularly true in the mountains of Appalachia, where the problems of mining; and of reclamation are made more intense by the nature of the terrain. Mining and reclaiming the land "by the book' --which is to say by the methods of contour mining traditionally used in hill country--hasn't worked too well. So a lot of conscientious coal operators and associations are trying new methods--new ways of mining, new machines for seeding and planting, and new species to seed. Not all their experience can be transplanted to other areas, and of course I don't believe that Appalachia is the only place where new methods are being developed. Nevertheless, there's enough action in Appalachia to make a detailed examination rewarding, so let's focus on the hills to see what's new.

Jan 1, 1970

By German Zambrana

The solution of the problem of beneficiation of cassiterite from its primary ore deposits is of fundamental importance to Bolivia. The process today involves a gravimetric treatment of the ore followed by sulphide flotation. During the last year, a cassiterite flotation stage has been added in several plants to treat the slime tailings. Although cassiterite flotation is already economical for the slime tailings and the mechanism of the process are understood, it is felt that further research could improve the results. In the past, considerable amount of research and test ark has been performed to select appropriate collectors to improve recovery, to increa¬se the grade of tin in the concentrate, to minimize the effect of metallic ions like Ca+2, Fe+2 and Fe+3 which prevent flotation, and to increase the pH of the pulp which now it can not be higher than 3.0. It has been reported that the halogen salts (1) like NaCl exhibit special surface affinity for cassiterite but none for quartz. These effect seems to be favourable for the selective flotation of cassiterite from silica minerals. In view of these preliminary results it was decided to follow the research accordingly: OBJECTIVES The objectives of the present investigation are: 1. 0 evaluate the influence of NaCl salts in quartz and cassiterite flotation.

Jan 1, 1971

By Robert L. Grayson

An application of goal programming (GP) in evaluation of proposed purchases of major mining machinery is presented. It incorporates historical operating data compiled on mechanical delays to production time. The goal programming technique, which is an extension of integer programming, is used to maximize an objective function. The objective function combines the capital budgeting evaluation methods of net present value, payback period, profitability index, and total net earnings as goals weighted according to a management preference. The GP method gives an optimal solution to a multiple-goal problem. A sensitivity analysis is performed to determine the effect of an increased production forecast or a tightened budget on proposal selection.

Jan 1, 1982

By James M. Prudden, E. P. Jucevic

The Divide mining district occupies the center of a Tertiary caldera hosting the famous Divide silver lode and the crosscutting Gold Mountain mines. The northwest-southeast trending silver lode hosted ore with typically a 100:1 silver:gold ratio, high molybdenum content and argillic alteration dated at 16.5 m.y. within the Fraction Tuff. The east-west trending Oddie Rhyolite flow dome at Gold Mountain experienced possibly several periods of resurgence with repetitive silicification, brecciation and attendant precious metal deposition forming stockwork type mineralization. Silver-gold ratios average 10:1 for the mineralization phase of this 16.4 m.y. intrusive event. Similar chalcedonic mineralization registering a 3:1 silver:gold ratio cements conformable breccias within the Oddie Rhyolite basal flows unconformably overlying the Siebert Tuff on the northern flanks of Gold Mountain. Gray and red chalcedonic breccia matrix in the King Tonopah member of the Fraction Tuff contains a 50:1 silver :gold ratio.

Jan 1, 1990

By S. J. Ristorcelli

Historically, geologic data has not been adequately considered in resource estimation. More recently, with the use of computers and sophisticated estimation algorithms and geostatistical justifications, geology has been downplayed further. Many reasons are given for not using geology including cost, time and irrelevance. None are valid. Boundaries defining mineral domains should be used in computer-generated resource estimates. Selected case histories show how the failure to honor geology has caused discrepancies in resource estimates of actual in-place resources. After-the-fact differences have included decreases in tonnage of up to 50% and increases up to 300%; partial to complete recategorization of material; and 50% decreases in grade. The costs of gathering and using geology are trivial compared to the potential consequences.

Jan 1, 1994

By Eric R. Braun

Ore reserves in the Republic mining district were nearly exhausted in 1984 when hole D-54 intersected a vein twenty- eight feet in drill width averaging 1.57 opt gold and 11.95 opt silver below post-mineral lake beds. The discovery area, termed "Golden Promise", has announced proven and probable ore reserves of approximately 372,000 tons averaging 1.0 opt gold and 4.5 opt silver, and drilling indicates another 756,000 tons of mineralized material containing 0.37 opt gold and 1.4 opt silver (Hecla fourth quarter 1986 report). This paper describes new geological interpretations made as part of a district research study sponsored by Hecla Mining Co., which led to the D-54 discovery. Important new geological concepts include: 1) re-interpretation of the volcanic stratigraphy of the district and recognition of a suite of pyroclastic rocks that are unique to the Republic graben, 2) identification of disseminated subaerial mineralization at a paleosurface that corresponds to the newly described upper contact of the Sanpoil Volcanics, 3) recognition that epithermal veins have a maximum productive vertical range of 0-500 meters, measured from the paleosurface, and 4) veins exhibit visual and geochemical vertical zoning within the productive zone with highest gold occurring at an optimal depth, which is interpreted as the average depth of hydrothermal boiling.

Jan 1, 1987

By Peter G. Zambas

In planning an underground room and pillar mine, the selection of the shaft or portal location and the orientation of the main haulage arteries is of paramount importance, particularly in view of the high dependence of the cost of truck haulage on the proper definition of these parameters. In an effort to facilitate this selection a computer program was written which, by relating the truck characteristics to the areal configuration of the property or ore-body, derives the volume-weighted total fuel and time requirements for hauling ore from every panel within the property to a specified portal or shaft location through a predetermined gridwork of haulage drifts. By varying the size and orientation of the gridwork and the location of the portal or shaft access, an infinite number of configurations can be investigated. The results of this analysis can be plotted to indicate the optimum conditions.

Jan 1, 1971

By W. R. VanSlyke

Scrubbing is gaining increasing recognition as a valuable tool in the treatment of Mesabi Range intermediate iron ores. In general, the earliest washing plants included log-washers in their various flowsheets. While log-washers certainly did impart a degree of scrubbing to the crude ore, such treatment bears little resemblance to the type of scrubbing being practiced today. At the time that these early plants were erected, only the true wash-ores were being processd. ("Wash-ores" are defined as crude ores in which relatively coarse chunks of almost completely liberated iron are found in a matrix of loosely-consolidated fine sand.) To treat ores of this type, sizing at approximately 65 to 100 mesh was sufficient to produce a merchantable concentrate. As crudes were being treated in which there was little "locking" of iron and silica, log-washers tended to disappear and large screens and classifiers took their place in Mesabi range flowsheets. The "screening and classification" type of flowsheet 'had its greatest usage in the 1945-55 period, generally speaking. During this same period, many operators found it necessary to supplement the "wash-ore" type flowsheet with heavy-media treatment.

Jan 1, 1959

By Yiming Sun, David Tsztoo, Rick Nolting, Adam M. Wirthlin, Rebecca Fusee

"Excavation and initial support of the New Irvington Tunnel presented significant challenges, including rapidly changing ground conditions, heavy ground loads, and squeezing. Such behaviors were anticipated from historic tunneling records of the adjacent Existing Irvington Tunnel, and extensive site investigation, but clearer understanding of their actual extent and causes has resulted from convergence measurements, observations of ground behavior, initial support monitoring and detailed geologic mapping. Time-dependent movements, documented hours to months after excavation in clay-rich rock and in moderately to intensely fractured rock, identified squeezing areas, allowed classification by currently-used predictive methods and added to the list of lessons learned in tunneling such ground. INTRODUCTION In March 2003 the San Francisco Public Utilities Commission (SFPUC) authorized funding for the $4.6 billion Water System Improvement Program (WSIP) to repair, replace, and seismically upgrade its water system. The program consists of 35 local projects located within San Francisco and 48 regional projects located in several counties from the Sierra foothills to the San Francisco Bay Area. The New Irvington Tunnel (NIT), a key component of the WSIP, is located east of Fremont in Alameda County, on the east side of San Francisco Bay. The NIT is a new 18,660 foot (5,689 m), redundant tunnel, 190 to 670 feet (58–204 m) offset from, and subparallel to the Existing Irvington Tunnel (EIT). Built between 1928 and 1932, the EIT was constructed with an unreinforced cast-in-place concrete lining and is vulnerable to damage in the event of a major earthquake along the two closest active faults. The Hayward Fault is located less than a mile west of the tunnel, and the Calaveras Fault is located half a mile east of the tunnel. Although the alignment does not intersect these faults, the shaking and sympathetic displacement along secondary faults that cross the tunnel alignment are potential hazards. The NIT provides a seismically reliable water transmission facility capable of withstanding earthquake damage and maintaining continuous water service after a major earthquake. The NIT also adds system redundancy and provides for operation flexibility of running water through both tunnels, or through one tunnel while the other is out of service for inspections and maintenance."

Jan 1, 2016

By Mark J. Schultz, William J. Francart, Michael P. Snyder

The Pittsburgh Safety and Health Technology Center surveyed MSHA Coal Mine Safety and Health Districts to monitor the implementation of computer based atmospheric monitoring systems (AMS) in underground coal mines. This survey was first completed in 1984, and has been periodically updated with the latest update completed in 1995. The utilization of computer based monitoring systems has steadily increased over the past 12 years, with over 16 percent of all producing underground coal mines using this technology in 1995. This paper discusses the results of the MSHA 1995 AMS Survey.

Jan 1, 1997

By Paul Grisley

Air-supported belt conveyors-conveying systems that replace troughing idlers with a film of air-were a revolutionary concept when introduced in the 1970s. But high installation and operating costs limited their application. Now, system refinements have led to successful applications, even under the challenging conditions of mines and process plants. In this presentation the author will discuss the latest developments in the engineering of these systems, including the ability to retrofit existing transfer points with modular air conveyor components. Air conveyor applications and limitations in mineral-handling operations will also be examined.

Jan 1, 2002

By J. Philip Bromberg

The 1977 Clean Air Act Amendments will have a large effect on the coal-fired segment of the electric utility industry. Since electric power generation constitutes by far the largest single use for coal, this legislation has the potential to greatly affect future patterns of coal utilization in the U.S.A. The inability to depend exclusively upon low sulfur coal as an exclusive mode of compliance with New Source Performance Standards may greatly lessen projected demands for low sulfur coal by eastern utility boilers. The requirements of the legislation is discussed with particular reference to the needs of the electric generating industry, along with the technologies available for complying with the Act.

Jan 1, 1978