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By Nan Hua

As a high production and high efficient mining method, top coal caving method is now widely used in China. However, as more extra-thick coal seams are mined, it becomes more and more difficult to make the top coal fully broken up, resulting in more and more top coals flowing into the gob, rather than onto the rear AFC at the working face as designed. This research is aimed to investigate the failure mechanisms of the extra-thick top coal caving mining method.

Jan 1, 2009

By Hamid Maleki

Mine seismicity is influenced by the mechanical properties of both near-seam rocks and overburden and the prudent selection of mining methods and mine layout designs. Using finite-difference modeling, experience in many U.S. mines and measurements of the pressure arch width, the author has reviewed the engineering design factors that control seismicity in room-and-pillar retreat operations for stiff stratigraphic conditions in deep western U.S. mines. By back analyzing the overburden response in now understood to have been inadequately designed historic room-and-pillar mine, the overburden collapse mechanism is addressed as well as the need for improvements in designs including panel and barrier pillar widths, and sequence of retreat.

Jan 1, 2009

By Kourosh Shahriar

The occurrence of rock falls in underground coal mines entails detrimental effects as fatal or non-fatal injuries on workers, stoppages in mining operations and breakdown of equipment. In this paper, a risk assessment approach on the basis of a decision analysis trend is employed in order to assess the possibility of and manage roof falls. Risk is then assessed by determination of likelihood of occurrence and the cost of consequences (outcomes). In this regard, collected real roof fall data from Tabas and Kerman coal regions comprising of several underground coal mines are used. It is concluded that the annual accidents due to the roof falls occurrence in the all investigated mines are so high that it is economically feasible to improve the support systems and to implement a suitable educational program as well as an accurate supervision and other elements of safety management.

Jan 1, 2009

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jason Navoyski, Jennica L. Bellanca

The paper describes the process of collecting detailed accounts of near-miss incidents and turning them into impactful visual stories using graphic simulation. The aim is to create high-quality training materials to reduce haul-truck-related accidents and fatalities in mining.

Sep 1, 2023

By T. R. Ellis

Regulation of mineral property valuation methodology by governments and others is due to frauds, condemnation and takings, banking industry problems, and litigation. Definitions of "reserves," "resources," and "qualified person" continue to evolve, along with guidelines to the data and disclosure required to support valuations. A less recognized but vital issue relates to the regulatory acceptability of alternatives to the comparable sales method. Comparable sales generally work well for surface real estate, and sometimes for precious metal deposits, but not at all for most industrial mineral properties. Alternative methods, such as net present value, or a geoscience rating system, often provide better valuations. Yet US regulations dictate comparable sales as the preferred method. The task of convincing regulators of the inapplicability of comparable sales to mineral properties, particularly those lacking reserves, may be as important as the valuation itself.

Jan 1, 1999

By G. Bourque

Early in the design stage of their new concentrator for the Mount Wright Plant, Quebec Cartier Mining decided to use a process computer for total control of crushing, grinding and concentrating. A map of the area is given in figure 1 and a view of the plant in figure 2. Although the use of process computers is not a new idea in petrochemical and chemical industries, their use in the mining industry is very limited. We innovated in using the computer, not only for data logging, as we have seen in some other plants, but a sole operator located in the administration building, starts and stops mill lines, crushers, load-out system, tailings, thickeners, etc ... by means of a CRT console. Our process is fairly simple as can be seen on the schematic process flow diagram (figure 3). .The ore, carried by 136t diesel electric trucks, is dumped through ore pockets onto two primary pan feeders. The feeders supply two 1,52mx2,79m gyratory crushers which reduce the ore to minus 20,32 cm. Each crushing line have a capacity of 5600t per hour and feed a shuttle conveyor distributing the crude ore into six silos.

Jan 1, 1979

By William S. Fyfe

The world's biomass with its species-specific ability to concentrate metallic elements must provide one of the dominant concentration and transport systems for such elements. Given that about thirty elements are now considered bio-essential, for all these biomass may control their environmental behavior. Life appears to be present in almost all places where liquid water is present at temperatures near 100°C or below. In the surface environment a very large array of simple minerals are produced in living cells and such processes can lead to economic concentrations. Because of the specific nature of bioconcentration of elements, in all environments where biomaterials accumulate, interesting metal concentrations may occur or the molecular fragments from bio-degradation may allow specific metal transport and concentration. The scale of biological-inorganic interactions on our planetary surface is still inadequately appreciated.

Jan 1, 2013

By A. Cecala, J. Noll, J. Hummer

The National Institute for Occupational Safety and Health has observed that many control rooms and operator compartments in the U.S. mining industry do not have filtration systems capable of maintaining low dust concentrations in these areas. In this study at a mineral processing plant, to reduce respirable dust concentrations in a control room that had no cleaning system for intake air, a filtration and pressurization system originally designed for enclosed cabs was modified and installed. This system was composed of two filtering units: one to filter outside air and one to filter and recirculate the air inside the control room. Eighty-seven percent of submicrometer particles were reduced by the system under static conditions. This means that greater than 87 percent of respirable dust particles should be reduced as the particle-size distribution of respirable dust particles is greater than that of submicrometer particles, and filtration systems usually are more efficient in capturing the larger particles. A positive pressure near 0.02 inches of water gauge was produced, which is an important component of an effective system and minimizes the entry of particles, such as dust, into the room. The intake airflow was around 118 cfm, greater than the airflow suggested by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) for acceptable indoor air quality. After one year, the loading of the filter caused the airflow to decrease to 80 cfm, which still produces acceptable indoor air quality. Due to the loading of the filters, the reduction efficiency for submicrometer particles under static conditions increased to 94 percent from 87 percent.

Jan 1, 2015

By M. E. Breitrick

Newmont Gold Company began full production in early 1995 at the Carlin East underground mine. The mine is currently producing at the rate of 900 tpd (1.000 stpd). for an annual production of 150.000 ounces. Approximately one hundred twenty five hourly and salary personnel are employed at the project for the estimated six-year mine life. Two mining methods are currently utilized at the mine. Longhole stoping with cemented backfill accounts for 70% of the total mine production. Conventional underhand drift and cemented fill accounts for the balance of the daily tonnage. In December 1996. Newmont purchased a new AC-Eickhoff ET-210 Roadheader. The machine went into service in mid-June of 1997 and is used in both longhole stope topcut development and cut and fill production at a rate of 225 tpd (250 stpd). The Carlin East mine is operated by Newmont Gold Company. The mine is one of four underground gold mines in production in northeastern Nevada owned by Newmont Gold.

Jan 1, 1998

By Rongjie Kong, Shiwei Wang, Guomin Wei

Owing to the selective oxidation and uneven combustion that occur on the surface of carbon anode, some carbon particles detach and form carbon residue, which is defined as spent anode slag (SAS). The highly graphitized and toxic impurities such as fluorite ( CaF2), corundum (α-Al2O3), and cryolite ( NaAl11O17) are crucial components of SAS resource but are difficult to separate from graphite. This study developed a method of using water-soluble (emulsified) kerosene to separate the carbon particles from the toxic impurities in the SAS resource. The flotation purification approach of utilizing conventional kerosene was experimentally investigated and compared with that of using water-soluble kerosene. The results showed that with the use of emulsified kerosene, the maximum combustible matter recovery of the carbon particles was 89.86% while that of using traditional kerosene was 80.30%. The emulsified kerosene was comprehensively examined by various instruments to clarify its adsorption mechanism on the carbon particle surfaces. Because of the superior dispersibility of emulsified kerosene, it effectively envelops carbon particles with a smooth surface, oxygen-containing functional groups, and hydrophilic C–F bonds, thereby increasing the surface hydrophobicity and flotation responses of targeted carbon particles.

Feb 6, 2024

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

As the surface reserves are being depleted, more and more stone operators are seeking underground mining options. Stability of underground openings is a major concern for the safety and productivity. This paper relates to a field study conducted at a large underground limestone mine in Central Pennsylvania. Identification of hazards leading to ground failures and assessment of roof fall risks are important in mitigating injuries. Field observations at this mine were integrated with Roof Fall Risk Index (RFRI) mapping software recently developed by West Virginia University. The system is designed to combine field study data related to geologic factors, mining-induced damages, roof profile, and ground water influx to generate RFRI maps. The mine has adopted a proactive ground control program consisting of comprehensive examination of drilling and bolting logs; precision surveying of roof and rib; accurate mapping of cutters, falls, and geologic structures; and installation of extensometers and microseismic monitoring systems. Investment of time and resources has eliminated fatalities and lost-time injuries due to ground fall. This paper presents the geologic settings, mining conditions, ground control issues along with risk management and control techniques adopted at the study mine.

Jan 1, 2009

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 Jeffrey K. Whyatt

The Crandall Canyon accident investigation included an interesting and unexplained observation by rescuers that the ?barrier rib had shifted northward as a unit, as much as 10 feet.? This is not the first mention of such a movement, although such reports are rare. Historical accounts describe unusual movement and displacement of intact coal, cribs and timbers. Two movements of particular interest are the creation of gaps above coal pillars and falling of standing support elements without apparent damage. A dynamic boundary element program was used to explore movements induced by slip on geologic features removed from the affected panel. While the resulting models are much too simple to fully replicate these observations, they do show that the types of phenomena observed are possible. They can also provide insight into the types of motions that ground support elements are subjected to during large bump events. This was demonstrated for the case of a large bump in a Book Cliffs coal mine. Seismic information suggested the source mechanism to be normal slip on a fault. A model of that source showed initial dilation of the panel followed by dynamic compression and rebound ? consistent with underground observations. The initial dilation is important as it may allow slender standing support to shift or fall.

Jan 1, 2009

By T. Shumka, M. J. Druckenmiller

"INTRODUCTION As we push further into the 21st century and closer to a more efficient mine, safety and operational enhancements are the two major keys towards attaining success. The Crusher Vision Automation System (CVAS) is a technological advance that will allow an operator to achieve higher safety and higher operational goals in the same piece of equipment. The CVAS is a patent pending system and method for measuring and maintaining the closed side setting (CSS) on gyratory crushers. In the same equipment and technology package, the CVAS will also allow safer placement of main shaft pieces for maintenance and replacement. This technology yields multiple uses and allows a site to significantly enhance safety and operational efficiencies. This measurement technique is used to provide more accurate data and faster data collection times than current techniques used today. It will give crusher operators accurate and reliable measurement for the CSS in a live, operating environment. Measurement data can be collected in five minutes allowing for fast adjustment of the mantle position and subsequent enhancement and streamlining of a crusher and downstream flowsheet. The advantage of this system is that it is permanently mounted at the crusher location, where the operator can turn the system on and off as many times as they like throughout the day with a goal of maintaining a constant CSS gap based on production and maintenance criteria to help streamline operations and enhance safety efficiencies.Regarding its other main functional area, mainshaft maintenance, it allows this work to be performed remotely while keeping personnel safer and out of harm’s way. SAFETY ENHANCEMENT The safety factor enhancement with this system is extreme. It does not require the use of overhead cranes, cleaning out the crusher, lowering people into the crusher or having the operator lower paint cans or lead balls into the crusher pocket while the crusher is in operation for measuring the setting. In order to perform the CSS measurements, the operator only needs to operate the laser through manipulation of a joystick while watching the video feed. Danger of a person falling into the crusher while trying to take measures is eliminated, as are the effects of handling lead balls and tracer dyes."

Jan 1, 2015

By Vivas

Goldcorp is one of the largest gold producers in the world with projects in South, Central and North America. Goldcorp?s flagship operation is Peñasquito, a world class, polymetallic deposit that started production in 2010 and is one of the largest mines in Mexico. Since the early stages of the project, Goldcorp has used the most advanced technologies available to maximize its value. However, the implementation of optimum mine plans has been challenging to put into practice. This is due to the fact that the mine operation involves more complexity than the plans usually reflect. This challenge is an industry-wide issue that presents opportunities for improvement. This article discusses the mine planning methodologies and procedures used to connect long-, medium- and short-term planning strategies in order to bridge the gap and produce optimum mine plans that can be practically implemented in the field.

By Jamal Rostami, Tala Tahernia

TBM utilization rate is a component of machine performance prediction and critical for developing a reliable estimate of the construction completion time and cost of the tunnel. Estimation of the utilization rate involves identifying and quantifying the time dedicated to each activity in a tunneling jobsite. Ring building is a common activity in TBM tunneling and takes a large amount of tunnel excavation time when using shielded TBMs. This paper concentrates on the effect of tunnel diameter on the duration of downtimes related to ring building and examines the impact of machine diameter on downtimes. For this purpose, the dependency of segment installation time to segment configuration, and also the diameter of the tunnel was investigated. Furthermore, the ring building time for four tunnels with different sizes of diameters and a variety of ring arrangement were analyzed and the relationship between TBM diameter and segment installation time and consequently TBM utilization was evaluated.

Jun 13, 2021

By C. Zhou, R. Jacksha

This paper reports measurement results for radio frequency (RF) propagation around 90° corners in tunnels and underground mines, for vertically, horizontally and longitudinally polarized signals. Measurements of signal power attenuation from a main entry into a crosscut were performed at four frequencies — 455, 915, 2450 and 5800 MHz — that are common to underground radio communication systems. From the measurement data, signal power loss was determined as a function of signal coupling from the main entry into the crosscut. The resultant power loss data show there are many factors that contribute to power attenuation from a main entry into a crosscut, including frequency, antenna polarization and crosssectional entry dimensions.

Jan 1, 2016

By Rollin A. Slater

The bulk materials handling industry has served silently for years as the skeleton structure and often the central system of nerves and nourishment for the body of basic production industries. During the past two decades, this body has undergone substantial growth and mutation to meet the surging demands of our national economy for more and better products. The steel industry has been prominent in this phenomena and plants of the sixties are as unlike the second war vintage as our current crop of basketball players differ from their fathers. Steel has kept pace with spiralling demand by innovation which has resulted in new processes and improved designs which generally yield greater production from fewer units. The supporting industry of materials handling has likewise improved its techniques and currently has a new stronger generation of equipment to perform its necessary supporting function. It has been my fortunate experience to have been instrumental in the creative stages of several new steel mills which are currently in conceptual design or actual construction. Drawing upon exerpts from this experience, this paper will describe a basic approach to the selection and application of modern bulk materials handling systems to an entirely new steel plant. Specific details of past work are not available for publication, therefore, the plant described herein is a composite of ideas and will be the new plant of the Hypothetical Steel Corporation which will be located on the lower shores of the Great Lakes.

Jan 1, 1967

By Sean Harvey

One of the manifestations of the dynamically induced failures in deep coal mines is the violent ejection of coal from the ribs. A possible protection against such failures is the use of a specifically designed dynamic support system with reinforcement units having the sufficient capacity to absorb the kinetic energy of the dynamic failure and a skin support that can adequately contain the disintegrated coal. With this method of mitigation in mind, a recently introduced yielding rock bolt, trade name Roofex, has been identified (Harvey and Ozbay, 2009) as a possible energy absorbing component of a dynamic support system. According to the manufacturer?s specification, the Roofex bolts can yield 300 mm (or more) displacement while holding 80 kN pull load. In order to assess the performance of this support unit in coal ribs, a series of in situ pull tests performed in two coal mines in Colorado. The results show that, under conventional pull test loading conditions, Roofex yielding bolts perform very close to their claimed specifications, thus showing a potential for their use as the main energy absorbing component of a dynamic support system. Further studies are required to confirm the in situ performance of these bolts under dynamic loading conditions and also to develop a containment component for a dynamic support system for the mitigation of dynamic coal rib failures.

Jan 1, 2009