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By H. Sevim

Three transportation and handling alternatives for delivering dry coal combustion residues from power plants to underground coal mines were evaluated technically and economically. The objective was to transport, handle, and inject the residues into the old workings of the mine at a minimum cost. This objective was accomplished in two steps: I) Simulation models were developed and utilized in identifying technically feasible designs in each alternative, 2) Technically feasible designs were economically evaluated to obtain the cost-per-ton of material transported. The designs that provided the minimum cost-per-ton were declared optimal An analysis was conducted for varying distances and tonnages to reveal favorable operating ranges of each alternative.

Jan 1, 1996

By J. Paraszczak

Application of teleoperated and automated (or ?autonomous?) mobile equipment in underground metal mines is a promising avenue for overcoming some of the challenges facing mine operators. These include, but are not limited to, the issues related to safety and health of underground workers, better use of the shift time leading to increased productivity, skilled manpower shortages, and remoteness of some mine sites. Autonomous load-haul-dump machines and trucks offer several benefits over man-operated ones, but their use at their full capacity is a challenging and complex task. This paper makes an overview of commercially available equipment and systems and their applications. It examines factors affecting adversely availability, utilization, and production efficiency of autonomous vehicles and compares them to conventional man-operated machines. Technical and operational aspects are discussed and their criticality is analyzed. Based on that, recommendations concerning means and measures that may help raise operational effectiveness are given. It is stressed that due to a scarcity of publicly available information on the performance and cost of autonomous loading and haulage operations, more field studies and in-depth analysis are needed.

Feb 23, 2014

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. Y. K. Yang, O. Olajide, E. H. Cho

"This study focuses on partial leaching of coal pyrite with sodium sulfite in order to increase its degree of liberation from the coal matrix, which might help to increase the removal of coal pyrite, together with trace elements of arsenic (As), selenium (Se) and mercury (Hg) by froth flotation. The U.S. Bureau of Mines’ two-stage reverse flotation process was applied to further reject coal pyrite in the second stage, where pyrite was floated while coal was depressed. The results show that the leached coal flotation with sodium sulfite produced lower pyritic sulfur content in the clean coal by approximately 25% compared to the flotation of unleached coal. The synergism mechanism between the leaching and the two-stage flotation is delineated. The rejection of trace elements (As, Hg and Se) after the two-stage flotation process with unleached coal followed approximately that of pyritic sulfur (64.6%). However, after the two-stage flotation with leached coal, the rejection of Se was as high as that of pyritic sulfur (77.9%), while the rejections of As and Hg were 20% lower than that of pyritic sulfur, or followed approximately the same rejections obtained through the two-stage flotation with unleached coal.IntroductionSO2 is a reducing reagent, but when it is combined with oxygen in an acidic solution, it will become a strong oxidizing reagent for leaching coal pyrite. Sundaram et al. (2001) found that the reagent could leach coal pyrite to produce ferric iron, which, in turn, catalyzed the oxidation of SO2. Similarly, Cho et al. (2009) found that the reagent could leach pyrite as well as mercury from coal. In the present study, coal was preconditioned by partially leaching coal pyrite in water-coal slurry with sodium sulfite at 48° C. The partial leaching of coal pyrite may enhance its degree of liberation from the coal matrix and give a chance to be rejected more effectively during the flotation.The two-stage U.S. Bureau of Mines’ reverse flotation process (Miller, 1975) was used in this study. The first stage is conventional flotation, in which coal is floated while material with higher ash and pyrite content remains in the cell. Kerosene is used as a promoter to float the coal and MIBC (methyl isobutyl carbinol) is used as a frother. In the second stage, the floated coal from the first stage is depressed using a starch-based reagent, while coal pyrite is floated using potassium amyl xanthate. In this second stage, the liberation of coal pyrite from the coal matrix seems to be an important factor for successful rejection of coal pyrite."

Jan 1, 2015

By Samir Kumar Pal, Rajasekar Rathanasamy, Gobinath Velu Kaliyannan, Moganapriya Chinnasamy, Sathish Kumar Palaniappan

The research examines the performance of uncoated and coated tungsten carbide-cobalt rock cutting bits. It aims to optimize process variables (cutting speed, depth, coating material) considering multiple output responses (cutting forces, specific energy, wear rate, material removed, angle of reaction forces). The study uses a hybrid optimization technique combining Taguchi design, grey relational analysis, and fuzzy logic. The optimal parameter combination was found to be cutting speed: 200 mm/s, cutting depth: 6 mm, and titanium aluminum silicon nitride coating.

Apr 24, 2022

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 E. Baliktsis

We have searched and analyzed several modern technologies aiming at the best applications of environmental management, the studying of quarrying ? mining as well as the excavation sites ? utilization ? rehabilitation. We have used long-range reflectorless laser surveying systems, so as to achieve the fastest and most accurate surveying of the extractive work sites. We also used them, in order to collect field data, measure distances, surveying monitoring stations and environmental parameters ? data. Furthermore these systems can make the field work quite faster, more reliable and credible and have low cost in collecting data even in dangerous and non-approachable areas. We have used and processed on the field data in G.I.S. applications, in order to create 2-D and 3-D digital ground models. These G.I.S. applications present the existing relief and the management of the final stage of the area. The suggested techniques and works needed, for reclamation and utilization of the areas, could be tried, evaluated and well presented. The evolution and utilization of these ?smart? modern tools for the effective environmental management of quarrying ? mining ? extractive activity sites, will be presented by using case histories from the Hellenic territory.

Jan 1, 2002

By HASAN SERKAN GOKCEN, SERKAN CAYIRLI

The purpose of this study was to investigate the dry grindability of calcite powders in a vertically and horizontally orientable laboratory batch type stirred mill. The experimental results were evaluated using stress intensity analysis. The performance was also compared in terms of mill orientation. The results showed that the d50 values decreased with increasing stress energy down to a certain point and then increased for both milling orientations. Even though the optimum stress energies for both vertical and horizontal orientations were in the range of 1*10−3 to 5*10−3 Nm at 750 and 1500 kJ/kg energy consumption, the product size was finer for the horizontal orientation at the same stress energy value. Additionally, to the best of the authors’ knowledge, this is the first study to compare mill orientation (vertical vs. horizontal) for the same mill and under the same test conditions.

Apr 21, 2021

By Douglas R. Shaw

Normal dodecyl mercaptan was evaluated as a collector for flotation of sulfide minerals and precious metals. The reagent is from the class of normal mercaptoalkanes (n-alkyl thiols), and is commercially available in the form of a mixture of n-dodecyl mercaptan and a dispersant, under the trade name Pennfloat(TM)3. Reported are results of bench-scale flotation experiments on many commercially treated base metal and precious metal sulfide ores. Dosages, points of addition, and flotation pH were among the uariables studied. Most notable results were increased copper, molybdenum, and precious metals recoveries. Dosages of dodecyl mercaptan on some ores were considerably lower than required for conventional collectors.

Jan 1, 1979

By David B. McWhorter

Conventional analyses of seepage through saturated media do not apply when tailings impoundments are located above a partially saturated zone. Three stages of seepage are identified and methods for estimating the seepage rates and duration of each stage, based upon flow in partially saturated and saturated porous media, are demonstrated. The effectiveness of earthen liners is discussed and procedures for estimating the required properties of the porous media are provided.

Jan 1, 1978

By Todd Minoski, KRISTIN FLOYD, Michael Murphy, VASU GANGRADE, Gamal Rashed, DYKE MARK VAN, Brent Slaker

Underground stone mines frequently operate on multiple mining horizons or are required to undermine or overmine old workings. In these situations, the effects of pillar columnization and interburden thickness on the stresses surrounding mine workings are poorly understood. Many old workings were not designed to consider the effect on future undermining or overmining and, as a result, are laid out on irregular patterns and with pillar sizes that are difficult or impossible to replicate on adjacent levels. Additionally, as depth increases, even a consistent gridded mine layout may result in poor columnization due to the need to increase pillar sizes. Rules of thumb and past practice for designing multiple levels may often be effective. This paper explores the effect that multiple-level stone mining has on stress redistribution through the discussion of two case-study mines and associated numerical modeling to provide additional insight into situations which may cause concern.

By Yi Yang, Xiuzhu Su, Wei Sung Ng, Shuiping Zhong, Miao Chen

With over 260 tons of gold reserves, the Shuiyindong gold mine is one of the largest Carlin-type gold deposits in China. A particular challenge in the processing of the ore is the presence of carbonaceous compounds, which can cause substantial losses in recoveries via the preg-robbing and adsorption of gold. To investigate the structural properties of the native carbon and to compare between different characterization techniques for such compounds, pre- and post-flotation mineral samples containing 0.9–4.8% non-carbonate carbon from the Shuiyindong mine have been examined via mineralogical and thermogravimetric approaches, as well as spectroscopic techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine edge structure spectroscopy (NEXAFS), solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, Raman spectroscopy and preg-robbing measurements. NEXAFS and DRIFT yielded the most reliable results, indicating that 60–75% of the organic carbon in all samples consist of aliphatic alkenes with substantial unsaturated content, highly similar to activated carbon, with the remainder being graphitic and humic. Speciation by XPS was sub-optimal due to spectral overlaps between graphitic and aliphatic carbon, and between carboxylic and carbonate functionalities, while NMR spectroscopy could not provide reliable speciation of the carbon groups. The preg-robbing strength was strongly correlated to the aliphatic content and structural disorder in the carbon, while no such relationship was found with the graphitic and humic content.

Nov 29, 2021

By Nick Hasenack

In the pelletizing plant of Hoogovens, Estel BV, a varying mixture of hematites and magnetites is used for the production of acid and (occasionally) fluxed pellets. Optimum results regarding productivity, quality and process control are obtained with mixtures containing 30-40 % magnetites. A decrease of the magnetite ratio or an increase of the basicity has a great influence on both productivity and heat and power consumption. Tests have been carried out to find the extent to which magnetite can be replaced by b.f. dust, mill-scale and coke breeze. Pilot plant tests show that about 80-100 % of the production loss due to a decrease in magnetite content or to the increase in basicity can be regained without damage to the quality by adding coke breeze. The amount of coke breeze should be limited tot 1,5 %; if this percen¬tage is chosen higher, the quality of the pellets deteriorates rapidly. The amount of coke breeze to be added should be about 30 % above the theoretical value, based on heat balance considerations. The results achieved by incorporating b.f. dust and mill-scale into the pelletmix were also encouraging, but as some types of mill-scale are very difficult to grind and the supply of b.f. dust is limited, the research has not been carried out extensively in this field. The pilot plant tests on replacement of magnetite by coke breeze have been followed by industrial tests, during which the breeze was added to the ore feed before the dry-grinding system.

Jan 1, 1977

By M. L. Harris, J. Organiscak, S. Klima, I. E. Perera

"The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH’s Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners’ exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device IntroductionTwo recent regulations have modified operators’ rock dusting schedules in order to meet compliance standards. First, the 80 percent incombustible requirement in intake entries has increased both on-section and out by the- section rock dusting. Secondly, the recent change to the respirable dust regulation has increased the number of respirable dust samples taken per sampling cycle. Previously, when only five samples were needed bimonthly, rock dusting could be scheduled to not interfere with the respirable dust sampling schedule.The significant number of samples now required under new regulations, combined with the need to maintain 80 percent total incombustible content in active mining areas, require the schedules for respirable dust sampling and rock dusting to overlap. Although rock dust is considered a nuisance dust in relation to U.S. Mine Safety and Health Administration (MSHA) sampling, these overlapping schedules raise concerns about the amount of rock dust that potentially is included in the sample. Additionally, the respirable dust maximum was lowered from 2.0 mg/m3 to 1.5 mg/m3 effective Aug. 1, 2016, increasing concern that rock dust contamination may be an issue (MSHA, 2016). Currently, the acceptable practice is to apply administrative controls such as keeping the miners upwind during rock dust application, or to schedule rock dusting during a maintenance shift when the number of miners present is lower."

Jan 5, 2017

By Feng Junfa, Du Feng, Li Huamin, Syd S. Peng

"The Ordos coal field is located in the northern midwestern part of China (Fig. 1). Since the mid- 1980s, it has been developed into one of the major coal fields in the world, producing approximately 833 Mt (918 million st) of raw coal in 2013. There were once more than 400 coal mines operating in the region. However, due to the combination of market conditions and implementation of government consolidation policies, the number of coal mines operating in recent years has been reduced considerably, with increasing output.The surface of the Ordos coal field is covered with loess and alluvium layers of varying thicknesses. In many areas, their combined thickness may amount to as much as 100 m (328 ft) underlain by thin bedrock. Many loess and alluvium are aquifers receiving water from rainfalls. There are also gullies of varying depths crossing the coal field. Figure 2 is a typical stratigraphic column highlighting the coal seams and roof and floor rocks of interest.In conjunction with the development of highproductivity coal mines, numerous ground control instrumentation tests have been conducted in the operating longwall panels. Analyses of the results of those tests offer the opportunity to understand the effect of wide-ranging mining and geological factors on the overburden movement. For this reason, trips were made to coal mines of interest to interview mine management and collect their unpublished internal research reports on ground control instrumentation. In addition, literature searches on published thesis/dissertations and papers in the professional journals were performed. Finally, data from a total of 95 fully mechanized longwall panels were collected. The instrumentation involved primarily the monitoring of hydraulic pressures of longwall shields, from which the first roof weighting and first roof caving interval and periodic roof weighting and periodic roof weighting interval were identified and determined. Some panels also included measurements of roofto- floor convergence at the face, roof strata bed separation, longwall face sloughage and the height of caving and fractured zones in the overburden. Those 95 panels were located in 20 coal mines (Fig. 1) congregated along both sides of the Wulunmulun River with the following mining and geological conditions. All together those 20 mines produced more than 224 Mt (246 million st) in 2013, accounting for approximately 27 percent of the total coal production in the Ordos coal field:1. Period of mining: 1991-2013.2. Mining methods: All panels employed the one slice, full-seam natural-caving longwall mining method like those practiced in the United States. All panels were developed with a twoentry system with a single-row of chain pillars measuring 20- x 20-m (65.6- x 98.4-ft) wide.3. Coal seams (Fig. 3): Coal in Ordos coal field is high-quality steam coal, that is very low in sulfur, potassium and ash, but high in Btu. Data were collected in panels mined in a total of 10 seams with 82 panels in four seams and the remaining 13 panels in six seams. The first six seams (1-2, 2-2, 3-1, 3-2, 4-2, 5-2) were mined by the Shenhua Coal Group (the world’s largest coal company) and the #4-2, 5-2, 6R, 62, and 62R seams were mined by both the Shenhua and Yitai Coal groups. In each coal group, the sequence of mining was in descending order. For example, in Shenhua Group, the top seam 1-2 was mined first, followed by the 2-2, 3-1, 3-2, and 4-2 seam in that descending order. In Fig. 3, the top-down sequence of coal seams is listed from left to right in each coal mine group. All seams were near horizontal with dip angles less than 3°."

Jan 1, 2014

By P. Conrad, S. Rosenthal

"Engineers remain in demand. Job opportunities in the United States still exceed the number of students graduating from college with degrees in Mining Engineering. Although enrollment is up for freshman studying Mining Engineering, many of those students will either change majors or not complete their degree, maintaining that deficit of available Mining Engineers. What can be done to ensure that enough Mining Engineers will graduate to fill the needs of the mining industry over the next ten to 20 years? The authors believe that this need can be met by recruiting students to Mining Engineering programs who are genuinely interested in working in the mining industry. With this in mind, Montana Tech conducted its first Mining Engineering camp in July 2014 to get junior and senior high school students interested in careers in the mining industry by showing them that Mining Engineering is both an exciting and rewarding career. This paper discusses What a Blast! The 2014 Montana Tech Mining Camp. INTRODUCTION The concept of summer camps for high school students is not new. For example, Missouri University of Science and Technology has offered their “Explosives Camp” for several years. A large percentage of attendees to these camps discover or confirm an interest in Mining Engineering and enroll in the school’s program. The Dean of the Montana Tech School of Mines and Engineering challenged department heads to develop and offer summer camps for prospective high school students to get a taste of engineering with the goal being to improve recruitment for each discipline. Mining Engineering embarked on the concept of a summer camp in 2013 with a concept to provide a week’s experience in Mining Engineering during the summer of 2014. What it takes to progress from concept to reality, with some of the learnings to be shared, follows."

Jan 1, 2015

By Menglong Bian, Xiaotong Dong

Thermal damage is an urgent problem faced by deep mining. High-temperature rock mass, hot water and electromechanical equipment are the sources of the thermal damage. The increase in air temperature in mine tunnel is the result of fluid–solid coupling heat transfer from various heat sources. This paper takes a roadway with hot water and a mine car as the research object. Based on the Fluent, Static Structural and Steady-State Thermal modules in ANSYS, the thermal-fluid–structure coupling analysis in the roadway is carried out. It is found that the hot water has a significant effect on the thermal environment of the mine. Under the experimental parameters, the maximum heat flux density and equivalent elastic strain at the interface between the hot water and the rock are 9789.3 W/m2 and 0.00054532 m/m, respectively. The heat flux distribution in the rock area near the mine car does not change much, and the equivalent elastic strain value in this area is high. After the air is heated in the hot water area, the temperature curve changes gradually and then rises steadily. By changing the inlet air temperature parameter, it is found that the lower the inlet air temperature, the better the cooling effect, and the change of the inlet air temperature can change the air temperature field in the roadway as a whole. By changing the parameter of inlet air speed, it is found that higher wind speed brings better cooling effect, but with the increase in wind speed, the cooling effect of roadway thermal environment is very limited. When the wind speed increases from 5 m/s to 10 m/s, the air temperature of most measuring points drops by more than 2℃; when the wind speed increases from 15 m/s to 20 m/s, the air temperature of most measuring points drops below 0.7℃. After the wind speed reaches a certain value, the cooling effect of ventilation is very limited.

May 5, 2022

By W. A. Wilkinson

Mine planners are under pressure to evaluate the impact of changing economic times and newly acquired data on their mine plans. Incorporating changes such as commodity prices, customer sales, fluctuating cost assumptions and newly acquired geologic data requires quick turnaround for model building and planning to keep mine plans on pace with changes as they occur. Because of the length of time required to perform some of the geologic modeling and mine planning tasks, planning frequency may not be keeping pace with the frequency of change. To meet these challenges, one leading North American mining company successfully increased the frequency rate and accuracy of its mine plans to stay current with incoming data, ensuring its mine plans reflect the latest information, thereby minimizing or eliminating production cost variance.

Jan 1, 2010

By James C. Barker

Alaska?s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ?green? energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010). The REE, accompanied by other high field strength metals (such as Nb, Zr, Ti, Th, W), are associated with alkaline complexes of the Hogatza Belt in northwest Alaska; peraluminous tin-granites of the Ruby batholith in central Alaska and the Porcupine plateau in the northeast; and peralkaline intrusive complexes in the southwest Alaska Range west of Anchorage, and on Prince of Wales Island in southeastern Alaska. Limited evidence suggests that the heavy REE are associated with deposits that became more highly evolved by late hydrothermal processes.

Jan 1, 2012

By H. Sevim

Three transportation systems in surface coal mines: 1-Truck Haulage, 2-Belt Conveying, and 3-Coarse-Coal Slurry Transportation are compared from the operations and cost point of Views. Computerized design and cost models were developed and cost data banks were compiled for each system. These models can be used to evaluate transportation systems and layouts that are practiced in most of the U.S. surface coal mines. A typical midwestern area strip mine was considered for illustration purposes. Sensitivity analysis on critical parameters such as production rate, transportation, distance, etc. was conducted and the outcomes are presented.

Jan 1, 1990