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By J. Noll, A. Miller, J. Volkwein, C. Pritchard

Hecla Limited, Magee Scientific and the U.S. National Institute for Occupational Safety and Health (NIOSH) combined efforts to evaluate an in situ air filtration system for use in an underground mine environment. The purpose of the collaboration was to determine the efficacy of such a technology for reducing the concentration of airborne diesel particulate matter (DPM), with the aim of improving air quality in underground hardrock mines. A secondary goal was to evaluate the use of an aethalometer as a means of real-time measurement of black carbon as a surrogate for DPM. The evaluation included measuring the DPM-capture efficiency of the filter when it was preloaded with dust. Toward this end, rock dust was introduced at the filter inlet to create a dust layer on the filter surface, with the intent of providing improved capture of the much smaller DPM particles. The filtration efficiency for DPM was assessed by comparing measurements of DPM taken at the inlet and outlet of the system, using both realtime and time-weighted-average approaches. The real-time measurements were performed with a Model AE33 aethalometer, and filter samples analyzed by the NIOSH 5040 method were used to assess the effects of the system on time-weighted-average concentrations of total carbon. Results showed a reduction in DPM concentrations in the range of 82 to 89 percent. While the calculated efficiencies based on the two different measurement methods were similar, the DPM levels reported by the aethalometer were higher, possibly due to differences in the performance of the size selectors used for the two methods: impactors versus cyclones. More research is required to develop a robust correlation between the two methods to support the use of the aethalometer in future mining applications. The advantages of the aethalometer are that it can measure and record DPM levels for weeks at a time and can be directly connected to a mine monitoring system, potentially at multiple locations. Ideally, such data can be used to initiate the startup of the filtration system should DPM concentrations reach an action level. This work demonstrated that in situ filtration systems, modified to collect DPM and coupled with real-time monitoring, show promise in reducing DPM concentrations in the mine environment.

Mar 1, 2017

By Joseph F. Peters

The paper will begin with the physical parameters of design in a wire saw. These will include such things as the type of wire used, abrasives, horsepower of operation, and drive components. It will then go into the many uses of wire sawing in the quarrying and finishing of granite. This will include a step by step program of the removal of a block unit of granite from the quarry site through the finished slabbing and jointing in the plant. After this, there will be a small insertion of possibilities of wire sawing techniques in underground excavation work. This would be speculative only. I will use the example of powerhouse type of excavation work given to me by Dr. John Reed, and try to explain how I would attack this type of work using wire saws. Several slides of both design criteria and actual installations were shown.

Jan 1, 1997

By Bob Munz, Ry Stone

To facilitate the installation of the longwall equipment for each extraction panel, West Elk mine develops set-up room roadways that are between 26.5 and 30.5 feet wide. Historically at the mine, the set-up room roadways have been driven in a single 20-foot-wide pass, then incrementally widened to the required width during installation of the longwall shields. The first pass roof is supported with a generic roof support plan consisting of partially encapsulated roof bolts and point-anchored cables. This ground support plan was utilized regardless of the geotechnical conditions encountered in the roadways or consideration of the required stand-up time of the roadway before the longwall shields were installed. This "blanket" approach tends to result in over-conservative or inappropriate roof support designs, particularly in changing geotechnical environments. Guided by the desire to optimize the ground support plans and increase mining efficiency for future set-up rooms, the West Elk mine and Agapito Associates, Inc. have developed and implemented a strata management program. Strata management, as a formal and structured process, allows ground support and mining methods to be tailored to the anticipated and encountered geotechnical environment in a con- trolled manner (Thomas 2007). To arrive at adequate site-specific ground support plans for the set-up rooms at the mine, several struc- tured processes were utilized. Firstly, the geotechnical environment was characterized by examining the roof lithology and geomechanical properties from nearby rock core obtained from exploration boreholes. To increase both mining efficiency and continuity, and to achieve longer stand-up times before the longwall shields are installed, a multi-pass approach was implemented into the design. During mining, the geotechnical conditions of the roadway are mapped, and the roof is strategically surveyed with a borescope. This process was used to ensure that the encountered ground behavior was in alignment with the design standards used for the roof support design. To support this process with measured data, roof extensometers were strategically installed throughout the roadway. This data was used to monitor the magnitude of roof displacement at various horizons and record displacement rates up until the longwall shields were installed. Lastly, a Trigger Action Response Plan (TARP) was used during mining to cater for any unforeseen changes in ground conditions that would warrant additional con- trols such as increased monitoring or the installation of additional ground support. This paper presents two case histories at the mine where the above strata management approach was implemented to arrive at a site-specific ground support plan. The main changes to the mine's ground control plan included a multi-pass mining approach, the utilization of fully encapsulated roof bolts, and the transition to a stiffer roof support system. The geotechnical mapping, the roof borescope results, and the roof extensometer data will be presented to demonstrate the effectiveness of the ground support system up until the longwall shields were installed in both presented cases.

Jun 25, 2024

By G. M. Wali Ullah, MEHMET KIZIL, ` Micah Nehring, PETER KNIGHTS

In operations that use the sublevel stoping mining method, production scheduling takes into account factors, including ore reserve envelopes, ore grade averages, equipment capacity, feed controls to the mill, and geotechnical restrictions, across the scheduling horizon. Mathematical programming is one of the most effective methods for enhancing the decision-making process in regard to the most viable production schedule in light of a given set of limitations. The majority of research on sublevel stope mining focuses primarily on a single objective of optimisation, which is to maximise the net present value (NPV). Environmental, social, and governance (ESG) considerations are becoming more prevalent in the mining industry. This includes aspects relating to deforestation, land disturbances, gas emissions, community relations, and water usage, among many others. Institutional and other kinds of investors are becoming more interested in the work that resource companies do regarding their ESG obligations. This review article identifies the gap in the existing literature and proposes to simultaneously optimise the production schedule around three objectives. Two of these relate directly to ESG aspects.

Nov 6, 2023

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-yd3) transit mixer and a shotcrete spray boom carrier, is used bya 2-man crew to transport and place up to 25 m3 (32 yd3) of steel-fiber reinforced, dry, silica fume shotcrete per II-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control is performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1991

By Swades Kumar Chaulya, Vikash Kumar, Sushma Kumari, Naresh Kumar, Girendra Mohan Prasad, Monika Choudhary

During harsh weather conditions, the presence of fog, dust in the environment degrades the image’s quality, which affects the visibility of drivers of heavy earth-moving machinery in opencast mines. Due to low visibility, mining operations cannot be carried out as drivers are easily prone to accidents. This paper proposes a technique that includes developing a vision enhancement system called perceptive driving assistant system for increasing visibility of real-time video of the road in front of the vehicle for operators of heavy earth-moving machinery at opencast mines during harsh weather conditions to overcome the problem. The system consists of high-quality Internet Protocol cameras and thermal cameras for real-time image processing and other well-defined devices, which is quite capable of enhancing the visibility of the image, outlining edges of the road, and detecting obstacles present on the path of operators for smooth driving and reducing threat of accidents. A high-speed graphical processing unit has been used for quality-performance parallel computing, which is well suited for real-time operations to empower fast real-time operations. The calculated frame per second (fps) of image enhancement, object detection, and edge detection is 17.91, 15.91, and 25.09 fps, respectively. The actual frame rate is 26.07 fps, and after applying the algorithm, the final frame rate is 19.65 fps. The calculated accuracy of the object detection model is 81.23%. Field trials indicate that the developed system has performed adequately during foggy weather.

Sep 21, 2022

By Yongsik Jeong, Kwangmin Kim

Most tailings storage facility (TSF) failures occur in active, upstream-type TSFs, often due to extreme and unexpected weather conditions—specifically, heavy rainfall and strong winds. This case study of a TSF in southern Arizona examines the use of the optimum safe beach distance (Doptimal, the optimum distance between the crest and decant pond) as a tool for monitoring geotechnical stability and reducing catastrophic failures. A digital model of the TSF was used to determine the critical beach distance (Dcritical) under normal weather conditions, and Doptimal was then determined by adding incremental distances to account for the effects of heavy rainfall (Drainfall) and strong winds (Dwind). To overcome accessibility issues, a drone was used to map the TSF geometry and create a digital model. This model served as the basis for conducting a coupled stress-seepage, finite-element (FEM) analysis with a safety factor of 2.0 to assess geotechnical stability (Dcritical). The safe beach distance increments were determined using the PMP (probable maximum precipitation) and possible maximum wind speed. Based on this analysis, the optimal safe beach distance at the study site was identified as 202.2 m. Since the current beach distance (371 m) exceeds this value, the TSF was considered to be stable and satisfied the design safety factor of 2.0. However, this distance should be reassessed periodically to account for changes in the TSF geometry and other conditions. Furthermore, it applies only TSFs that are well-managed and feature a smooth, non-undulating beach surface with a consistent slope.

By S. G. Malghan

This paper describes uses of sodium sulfide in the flotation of oxide and sulfide minerals of copper, lead, and zinc. The activation and depression effects of sodium sulfide are of particular importance because of their applications with oxidized lead and copper ores. In spite of its industrial importance; however, the nature of the heterogenious reactions between sulfide ions in solution and the surface of oxidized minerals has not been fully understood. Hence, proposed mechanisms of the sulfide action in flotation, methods of measuring and monitoring of sodium sulfide in flotation pulps, and variables influencing the sulfide addition are analyzed. A review of recent studies shows that sodium sulfide addition to flotation pulps can be monitored and hence the optimum dosage controlled using the platinum and/or sulfide specific ion electrodes. The use of these electrodes for improved reproducibility of bench-scale experimental data and plant implementation of laboratory results is described.

Jan 1, 1985

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES

Lithium-ion battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12 V, 24 V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicated that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

May 4, 2023

By Aimee A. Woolsey

Enterprise Unmanned Traffic Management is a holistic system concept evolving from technological developments in radio frequency where dynamic tracking can be added into current and emerging platforms. This is done through inexpensive RF sensors capable of real-time and cooperative, non-GPS tracking enabling digital visualization of assets, including unmanned aerial systems (UAS). The RF sensors are low size, weight, and power (SWaP), creating efficiencies in energy and material consumption while transmitting positions in real-time and at long ranges. Multiple UAS and other unmanned vehicles can be visualized for risk mitigation in operations,

Oct 17, 2022

By R. W. Kobler

The pelletizing process for low grade iron ores has undergone continual changes since its inception over twenty years ago. These changes have necessitated filtration equipment changes in order to produce a product suitable for balling. With modern techniques it is now possible to produce pellets of 68% Fe from ores containing as low as 26% Fe. Low grade ores require fine grinding to liberate impurities This shift to finer grinds over the years has necessitated major changes in the filtration steps. Techniques are now available for producing suitable product from ores with Blaines as high as 3600 cm2/gram. This has been made possible by the development of high performance filters. Recent developments have reduced maintenance costs and produced higher production reliability. The paper discusses iron concentrate filtration from its beginning to present day design. It will be shown that the dewatering step prior to balling has gone through four generations of filters. Particular emphasis is placed upon hydraulic studies which have allowed today's optimum designs.

Jan 1, 1978

By R. Guardia, J. Hoskins, E. Claros, Y. Kamiya, R. Ramirez, J. Dalenz, P. Fernandez, E. Ilgren

Crocidolite is a well known causative agent for mesothelioma. Studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width. Epidemiological studies have shown that ‘thin’ fibers from mining areas of Western Australia and the Cape Province, in South Africa are associated with a high mesothelioma risk while exposure to ‘thick’ asbestiform amphibole fiber of the same fiber type are associated with little or no mesothelioma risk. This study is concerned with ‘thick’ Bolivian crocidolite but similar findings also probably explain the paucity of mesotheliomas in the Finnish anthophyllite, South African amosite and African Transvaal crocidolite mines. The findings from the present study suggest the incidence of mesothelioma in the three major cities of Bolivia is not significantly elevated above background even though Bolivian crocidolite has been used for the past 60 years commercially and residentially in all three cities. Although some cases of mesothelioma may have been missed due to a failure to reach hospital or a shortened natural lifespan, mesothelioma generally occurs after the age of 50, we cannot tell precisely the extent to which these were confounding. We suggest the most likely explanation for the lack of mesotheliomas despite the large populations at risk from the long and extensive residential and commercial use of crocidolite containing products, is related to an increased fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By E. J. Karges

The use of pulverized coal for generating power and performing industrial processes has made an important contribution to our industrial economy during the past half century. Actually, the burning of coal in powdered form is a subject that has held the attention of engineers for a century or longer. Its widespread use, however, is comparatively recent, As early as 1866 patents were granted to Messrs. Whelpley and Storer for a method of feeding pulverized coal into a furnace as an auxiliary to the grate fuel. In the many tests made during the subsequent years with various kinds of apparatus, the experimenters were handicapped in not getting the coal fine enough to obtain complete combustion and to prevent excessive formation of slag.

Jan 1, 1965

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Mar 12, 2021

By Dafydd Chandler, Milissa Hirst, Charles Hurst, Gary Snyder, Leszek Glodkowski

The Delaware County Regional Water Quality Control Authority (DELCORA) will be adding tunnel infrastructure to its wastewater conveyance system. This program involves the construction of a conveyance/storage tunnel and related facilities. The proposed 12- foot to 14-foot (±) finished diameter, TBM mined deep rock tunnel spans over 8.5 miles and lies approximately 80 ft-120 ft below the surface. The system is connected to the surface by at least five vertical online shafts and one offline shaft with associated 800ft long adit. This paper provides project details including data on the geologic conditions in which the tunnel will be constructed.

Dec 1, 2022

By David A. Heitman

The Buick Concentrator is a highly automated operation which utilizes a process control system for continuous monitoring and control. The process control system development, installation, and application to the concentrator grinding and flotation circuits are presented in this paper. The design and implementation of analog field sensing instrumentation, a continuous on-stream X-ray analyzer, grinding and classfication circuit controls, and a recent digital process control system utilizing a centralized computer are discussed. Emphasis is placed on the project planning and installation of the digital control system including a presentation of future plans for continuing application of computer control.

Jan 1, 1982

By J. Weng

The equations of heat conduction are numerically solved for two kinds of artificial freezing- mechanical freezing and liquid nitrogen freezing. A two dimensional finite difference model simulating the freezing field is developed. The procedure introduces a way to simulate the effect of latent heat released when water transforms from liquid to solid. The procedure also produces a way to calculate the harmonic mean of heat conductivity used when dealing with heterogeneous material. The theoretically derived temperature distributions in frozen soil are given and compared with measured data. An analysis is made on the thermal design in shaft freezing. The average temperature of frozen soil is calculated by using numerical integration. The regularity of development of frozen soil radius is revealed and given in an appropriate mathematical model.

Jan 2, 1984

By L. F. Ruppert, R. C. Milici

Coalbed methane (CBM) is currently being produced from a relatively small area in the Dunkard and Pocahontas basins, in the northern and central parts of the Appalachian Basin, respectively. In general, much of the production occurs where the coal beds are beneath 500 feet or more of overburden, where the rank of the coal is high-volatile B or greater (%Ro >0.8), and where the natural fracture system is enhanced by structural deformation. It is anticipated that near-term CBM development will continue within these areas and will expand in the Appalachian basin as technology improves and as the price of gas rises.

Jan 1, 2003

By Shaoyang Yan, Xinming Chen, Huazhe Jiao, Huaibao Chu, Chang Wang

In terms of the technical problems of rib spalling in large mining height coal face, a long-distance advanced pre-grouting layer flexible reinforcement technology is proposed in this paper. Based on the mechanism and failure mode of rib spalling in the coal face, the mechanical properties of the aluminum plastic composite pipe were analyzed by using the tensile and compression experiment. The deformation and strength characteristics of “flexible pipe + grouting” specimens were studied by uniaxial compression test, splitting test, and shear test. The UDEC numerical simulation software was used to simulate the reinforcement effect of “flexible pipe + grouting” at different positions. Combined with the field application, the feasibility of long-distance advanced pre-grouting layer flexible reinforcement technology was verified. The test results show the following: The coal face has the characteristics of brittle and large deformation. The aluminum plastic composite pipe has the characteristics of good elongation and tensile strength, which can endure the large deformation of the coal face. The “flexible pipe + grouting” can improve the tensile and shear strength of coal. The UDEC numerical simulation analysis indicated that the grouting hole layout of “flexible pipe + grouting” has a significant difference in the reinforcement effect of the coal face. Compared with single row grouting reinforcement, the reinforcement effect of double row grouting holes 1.5 m and 3.0 m away from the roof is better. According to the field application, it is feasible to use aluminum plastic composite pipe as a flexible grouting pipe to reinforce coal seam with 80–100 m long-distance pre-grouting. Long-distance advanced pre-grouting layer flexible reinforcement technology can improve the daily production of coal and reduce the support cost of the coal face. As a new method of reinforcement, long-distance layered flexible reinforcement has a significant effect on the prevention and treatment of rib spalling in large mining height coal face.

Sep 27, 2022

By D. Potter

Freeport Exploration initiated regional reconnaissance exploration programs in Irian Jaya, the easternmost province of the Republic of Indonesia in 1990 (see figure 1). Irian Jaya occupies the western half of the island of New Guinea. Freeport was awarded an initial contract of work which totaled 2.6 million hectares (6.4 million acres) and was subsequently awarded additional?concessions which added 1 million hectares (2.5 million acres). The concessions require work commitments and periodic relinquishments. Due to these relinquishments Freeport?s current land position totals l. 9 million hectares (4.7 million acres).

Jan 1, 1998