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By Congling Shi, Marek Borowski, Yue Wang, Jianwei Cheng, Xixi Zhang, Xuan Xu

As the first barrier to prevent accidents caused by explosions in underground coal mines, the integrity and stability of mine seals have great effects on mine workers’ lives and underground production safety. In this paper, the mechanical responding performance of typical mine seals under the impact load are studied by using numerical simulation method. By such simulation studies, the safety of different seals subjected to the explosion load is evaluated. Seals’stability are also investigated under effects caused by various influence factors including thickness of mine seal, cutting depth into surrounding rocks, rock type, and the roof-tofloor convergence under given the explosion load. The research results can provide theoretical basis and reasonable improvements for mine seal’s construction practices for improving its anti-explosion performance.

By James Carroll, Lance Heyer

This paper describes the shaft design and construction for a 72-inch microtunnel under 14 active railroad tracks in Avondale, Louisiana. Initial shaft design for a deeper tunnel alignment considered secant piles with a jet grout plug. Final design for a shallower tunnel alignment included contractor input with support consisting of braced sheet piles with a jet grout plug. The authors further elaborate on jet grout implementation in very soft organic clay soils and the practical limitations of jet grouting. This paper emphasizes how all project participants worked together to utilize value engineering and alternative delivery on a unique tunneling project with a focus on temporary shaft support.

Jun 23, 2024

By Kamran Esmaeili, MINGLIANG TANG

An understanding of the spatial and temporal variations of surface moisture content over a heap leach pad is essential for leaching production and to achieve a high ore recovery. The current leach-pad monitoring and data-collection practice remains highly labor intensive and exposes technical staff to cyanide solution, a hazardous material. To address these challenges, we propose using unmanned aerial vehicles (UAVs) equipped with thermal imaging sensors to remotely obtain image data with high temporal and spatial resolution for monitoring the surface moisture distribution over heap leach pads. A field study was conducted over a sprinkler-irrigated heap leach pad at El Gallo gold mine in Sinaloa, Mexico, and the acquired data were used to generate moisture distribution maps of the heap leach pad’s surface. The created moisture maps provide direct visualizations of surface moisture variation over the surveyed area. Such graphical results are effective tools for inspecting heap-leaching operations.

By Todd Burchett

Mining engineers spend countless hours and resources when designing a new underground coal mine. Their primary objective is to design the safest and most efficient operating mine with regards to coal production. A key variable often overlooked in this design stage is the slope conveyor. Typically, a slope conveyor is expected to operate with a 98-percent or higher availability. However, too often little effort is put forth by the mining engineer to optimize its design. Coal companies will rely on engineering, procurement, construction and management (EPCM) companies for the preliminary design, because the slope conveyor will be considered part of the surface material handling processes. This preliminary design will be used when soliciting quotations for the slope conveyor. Unfortunately, EPCMs may not have enough expertise with conveyors to optimize the design. This expertise is available with an original equipment manufacture (OEM) of conveyors, which ultimately may be responsible for supplying the slope conveyor. Each OEM will provide a bid package that represents what it considers to be the optimal design.

Jan 1, 2013

By Weijie Wei, Jinwang Zhang, Jiachen Wang, Yang Li

"Longwall top-coal caving (LTCC) mining technique is one of the important methods for underground thick seam extraction in China. The coal seam in LTCC panel is divided into two parts: bottom-coal and top-coal. The bottom-coal is mined by conventional longwall method while the top-coal is mined by caving method. The top-coal caving process in LTCC and block caving process in metal mine are both gravity flow of loose ore/coal blocks. However, the presence of caving shield in LTCC makes the characteristics of drawing body shape in the two caving processes differ a lot. This paper discusses the influence of caving shields on the characteristics of drawing body shapes in light of recent studies of the top-coal drawing process. The theoretical model for describing the drawing body shape in LTCC is proposed both along the seam strike and seam inclination. Then, the experimental data are used to validate the correctness of the theoretical model. Furthermore, two examples of how the theoretical findings assist LTCC mining are given and discussed.INTRODUCTIONLongwall top-coal caving (LTCC) mining technique and large-cutting-height mining technique have been widely used for extracting thick coal seams in China. About 0.6–0.7 billion metric tons of coal come from longwall top-coal caving panels every year. The maximum annual production is 15 million metric tons per panel _The mining method employed in such panel is a combination of top-coal caving mining technique and large-cutting-height mining technique, which is suitable for seam height between 12–20 m, as shown in Figure 1. Apart from China, LTCC has also been employed in some coal mines in Australia and Vietnam (Le et al., 2017).The coal seam in a LTCC panel is divided into two parts: bottom coal and top coal. The bottom-coal is mined by the conventional longwall method, while the top coal is mined by the caving method. The top-coal caving process in LTCC and block caving process in metal mines are both gravity flows of loose coal/ore blocks, as shown in Figure 2. However, the presence of caving shields in LTCC causes the characteristics of the drawing body shapes in the two caving processes to differ significantly.There are two main differences between the blocking method and the top-coal caving method:"

Jan 1, 2019

By MARK J. VANARELLI

Estimating ground-water inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies, including the Chattahoochee and Nancy Creek tunnels, for estimating steady-state ground-water inflows into deep rock tunnels. Statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations, and a semiempirical procedure was used to estimate ground-water inflows. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels that exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semiempirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Modeling using Monte Carlo simulations was observed to be an effective tool for removing data distribution irregularities and incorporating high-end permeability data to derive reasonable ground-water inflow estimates.

By Trevor Riters

Advancements in Emerson’s instrumentation technology have brought value and efficiencies to the mining industry. Some think of instrumentation as basic sensors and valves, but with our solutions, we equip operators with real time, accurate, and reliable data that they can use to operate more effectively. Working with Caltrol, an Emerson Impact Partner, we successfully engineered wireless skids for a leach pad to provide precise measurement and control of raffinate solution to many of the large mine sites in Arizona.

Feb 1, 2025

By Muhammad Kamran, NIAZ MUHAMMAD SHAHANI

This study elucidates a new idea to predict mine fire levels by employing several machine learning techniques. A total of 120 patterns of various mine fire influencing parameters, such as oxygen, nitrogen, carbon monoxide, and temperature, were compiled from the Adularya coal mine in Turkey. Techniques like t-distributed stochastic neighbor embedding (t-SNE) and k-means clustering were used to process the data, and support vector classification (SVC) was executed to predict various levels of the mine fire. The results revealed that the proposed model has higher credibility to predict the various levels of underground mine fires.

Feb 14, 2022

By M. Zaske, E. R. Mortensen

"As mine operators continuously look for ways to improve functionality and increase the capacity of their facilities, existing process equipment is often pushed to and past its designed limitations. As a result, equipment manufacturers are asked for economical solutions to meet redefined processing needs. Newmont Mining in Nevada was faced with such a need in its carbon-in-leach (CIL) train. In a collaborative effort between Newmont and Derrick Corp., tests were conceived to assess the viability of drop-in replacement screens using a three-dimensional screen panel. The synthetic pyramid screen panel was designed to increase flux while maintaining the existing equipment footprint. The test is the end result of an ongoing research and development project that Derrick undertook in an effort to refine and upgrade its urethane screening media. The application of this new screening media is presented for this CIL application along with future plans to implement the technology in trash, safety, carbon dewatering, carbon sizing and other scalping applications.In spring 2014, Process Machinery Associates (PMA), Derrick’s local area representative, met with Newmont to discuss the operation of the in tank screens in the CIL train at Twin Creeks, near Golconda, NV. The process was originally designed for about 12+ kt/d (13,000+ stpd) but the throughput has been steadily rising since the plant was commissioned. Newmont now requires 14.5 kt/d (16,000 stpd) to be processed. The original screens were running at their maximum capacity, and Newmont required additional screening capacity to continue the upward trend in production.Physical separation by use of screening is one of mineral processing’s oldest methods. Screening media can be prone to blinding and pegging, and the necessary support structures required for finer apertures result in smaller open areas. Therefore, more screening area generally requires larger panels and, thus, larger machines, screening media that does not blind or a combination of both.In an effort to avoid larger machines, Derrick had been working on a revolutionary threedimensional panel that would add nonblinding screen area in the same footprint of an existing machine. Alpha testing of the new screen panels began at Newmont Mill 2/5 in July of 2013. It was still occurring when PMA approached Twin Creeks about beta testing a refined machine and pyramid panel. After presenting the initial results, Twin Creeks determined that an upgraded machine and pyramid panels would be a possible solution to meet production needs. The testing of a machine eliminated the risk of capital costs to Newmont and provided Derrick the opportunity to obtain additional data."

Jan 1, 2015

By Oluwasegun Samuel Odebiyi, Shaona Wang, Feng Gao, Biao Liu, Hao Du

Recovering vanadium from vanadium titanium-magnetite (VTM) ore using ( NH4)2C2O4 is a clean hydrometallurgical process, but the drawback is the low recovery and slow kinetics due to the formation of inhibitor. A novel energy-efficient mathematical model was derived for green leaching of VTM in which the mechanical activation (MA) removed the inhibitor “δ” (formation of impermeable product layer of CaC2O4) covering the reacting core of the CaV2O6 leaching process in ( NH4)2C2O4 solution. Before the MA processing, the formation of the CaC2O4 layer affects the kinetics (slow) and NH4VO3 leachability (low recovery). The dissolution rate enhancement and economic importance (in terms of leaching kinetic/recovery) of mechanical activation (MA) pretreatment in hydrometallurgical processing cannot be overemphasized. It is shown from the experimental and developed mathematical model results that the rotating speed of the ball mill (ωb) has a significant effect on the NH4VO3 recovery. At 360 rpm, the experimental result gave an 82% optimum recovery rate and a reaction rate constant of 0.01889s−1 with close correlation with the present models at 82.8% and 81% for liquid-to-solid layer diffusion and chemical reaction controls, respectively, with a reaction rate constant of 0.018883s−1. The close correlation between the experimental recovery rate results and the diffusion recovery rate model result justifies that the leaching process is diffusion control shrinking core kinetic with experimentally measured activation energy (Ea) value of 19.502 kJ/mol . This present model proved that MA enhances the dissolution rate regardless of the formation of a passivation layer on the material and best describes the kinetics of the MA hydrometallurgical processes compared to the shrinking core model.

Nov 3, 2023

By A. B. Cecala

Video technology coupled with datalogging exposure monitors have been used to evaluate worker exposure to different types of contaminants. However, previous application of this technology used a stationary video camera to record the worker?s activity while the worker wore some type of contaminant monitor. these techniques are not applicable to mobile workers in the mining industry because of their need to move around the operation while performing their duties. the Helmet-Cam is a recently developed exposure assessment tool that integrates a person-wearable video recorder with a datalogging dust monitor. these are worn by the miner in a backpack, safety belt or safety vest to identify areas or job tasks of elevated exposure. After a miner performs his or her job while wearing the unit, the video and dust exposure data filesare downloaded to a computer and then merged together through a NIOSH-developed computer software program called enhanced Video Analysis of Dust exposure (eVADe). by providing synchronized playback of the merged video footage and dust exposure data, the eVADe software allows for the assessment and identificationof key work areas and processes, as well as work tasks that significantlyimpact a worker?s personal respirable dust exposure. the Helmet-Cam technology has been tested at a number of metal/nonmetal mining operations and has proven to be a valuable assessment tool. mining companies wishing to use this technique can purchase a commercially available video camera and an instantaneous dust monitor to obtain the necessary data, and the NIOSH-developed eVADe software will be available for download at no cost on the NIOSH website.

Sep 1, 2013

By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By Jacob Bouke, Jason Janisch, Erik Vlot

The use of conventional tailings deposition methods has been the standard for decades. With the need to reduce the impact of mining, alternative methods are considered when expanding or upgrading tailings handling systems. Converting an existing tailings management system to a more sustainable deposition method during the operation of a mine may incur considerable operational and financial risk, and when assessed more traditionally, does not provide significant advantages. As a result, most mines choose to continue their current technology and add an additional pumping stage or pumpstation to their tailings line in case of a pipeline extension or Tailings Storage Facility (TSF) expansion. This also often involves raising embankments. Changing pumping technology is traditionally assessed by comparing the energy efficiency of current and prospective pumping technology. Despite a reduction in absorbed power, this traditional assessment does not include possible savings in water and the carbon footprint. With the consideration of all these three aspects, alternative pump technologies, such as Positive Displacement (PD) technology, become more economically feasible, providing increased sustainability and enable a site to future-proof their operations. Project feasibility may be affected by the high capital investment required for PD pumps. The benefit of applying PD pumping technology could be enhanced by reducing the volumetric throughput of the pipeline by dewatering the tailings to 65% solids concentration by weight. It was found that despite increasing capital expenditure, the improved reclamation of water will have a positive effect on the direct and indirect cost of fresh water intake to mine operations. This paper seeks to illustrate that in many applications the long-term benefits of investing in sustainable tailings management are optimized when more efficient PD pumping technology is combined with tailings dewatering when upgrading or expanding the tailings handling system.

Feb 1, 2024

By Yiming Sun, John Stolz, Jakob Walter, Drew Mason

The Courthouse Commons SEM Tunnel was excavated within 6 feet of cover beneath two buildings in downtown San Diego utilizing high-precision geotechnical instrumentation. The excavated dimensions are approximately 25 feet in diameter and 328 feet in length connecting two in-service detentionlevel security buildings. Presupport includes large-diameter grouted canopy pipes and smaller pipe spiles. Initial support consists of fiber-reinforced shotcrete with lattice girders. This paper presents observed ground and structure behavior and lessons learned. During construction an unanticipated brick structure was encountered, and methods were developed to improve adhesion of shotcrete to sandy soil and to reduce rebound

Dec 1, 2022

By José Ricardo Lopes, Alaor Coelho, Marco Gomes, Alfredo Dacio Moraes Filho, Akira Koshima

"Very low strength alluvial peat soil was found under two old drainage galleries with just 4.3m cover above a twin tunnel due to be excavated by a 10.6m diameter EPB Shield for São Paulo Metro’s Line 5. Alignment was required to strengthen soil and drive the TBM through safely without damaging the galleries. The design included six levels of self-drilling forepoling with lengths up to 15m, using 100 mm-diameter SCH160 metal tubing and injection bulbs with estimated 0.20m diameter. Two 6m-diameter circular shafts were excavated along the shield-tunnel axis, one each side of the galleries, and forepoling fanned out under gallery foundations. Given the peculiar soil and confined working space, more data were needed for correct drilling geometry. Ground mass treatment was successfully designed and executed and galleries were fitted with instruments to enable the shield’s advance. DESCRIPTION São Paulo Metro’s Line 5 (aka Lilas or purple line) is adding 11 stations along an 11.5km extension and three EPB TBMs are being used simultaneously (three EPBs on the same job for the first time in Brazil) with one of them excavating a large cross- section twin-track tunnel. Currently the largest work-in-progress for São Paulo Metro, this project has been divided into seven lots and 9km are already operational. This study refers to Lot 6 where the 10.6m - diameter EPB shield excavation is only 4.3m below two galleries running through a 10m layer of very soft peat soil in an old alluvial riverside region ringed by major roads. After recent filling, this area (Parque das Bicicletas) was used for recreation, although temporarily it has become a construction site. This paper will describe the original basic design; precautions in relation to the structural condition of the galleries after inspection; the problem of absence of data for their foundations; subsoil bore tests; evolution of the engineering design for the galleries and conditioning and reinforcing the soft soil below the galleries to ensure safe advance of the EPB shield, and finally the successful outcome of the solution used."

Jan 1, 2016

By A. Jennings, J. Cornet, P. Perrone

Controlling long overland conveyors with multiple drive stations is a complex problem. The methods for controlling these belts in a steady state are well-covered in existing literature, but a discussion of starting and stopping strategies is absent. This paper outlines different control strategies for starting, stopping and running conveyors with multiple drive stations. To illustrate the benefits of applying the methods described in this paper, the authors show how their adoption corrected many of the control system problems at Essroc Cement’s overland conveyor, which features three drive stations separated from each other by long lengths of continuous conveyor belt.

Jan 1, 2013

By K. KAKLIS, O. SAUBI, Z. Agioutantis, R. JAMISOLA

Three-point bending (TPB) tests were conducted on prismatic Nestos marble (Greece) specimens. The specimens were instrumented with piezoelectric sensors, and comprehensive recordings of acoustic emission (AE) signals were obtained. Machine learning in the form of artificial neural networks (ANNs) was then applied in an effort to investigate whether specimen load evolution can be predicted as a function of AE signals. A number of ANN models were developed, and the optimum model was selected based on the highest coefficient of determination (CoD) value as well as the lowest root mean square error (RMSE) value that was calculated for each model. The best performing ANN model exhibits accuracy above 99% with an RMSE value below 4%. It can be concluded that ANNs can potentially be applied to predict rock behavior under load especially when such loads lead to failure.

Sep 7, 2022

By Nawal Kishore, Nilesh Pratap Singh, Amit Kumar Verma, Vikram Seervi

In India, demand for coal exceeds its countrywide supply, despite its natural abundance, due to failure to achieve high production targets, especially in opencast mines, which are responsible for 94.98% of total raw coal production within the country. Employment of technological solutions, such as surface miners, is key to achieving higher coal production and productivity in an eco-friendly manner, especially in the populated areas adjacent to the mining zone and, hence, require restricted blasting operations. It eliminates blast hole drilling, blasting, and primary crushing units, thus reducing related environmental hazards like ground vibration and fly rocks. This paper encompasses the applicability, advantages, constructional features, and performance assessment models for each working mode of a surface miner. The current paper discusses the correlation between coal production and key productivity indicators, namely, machine shift-time, pick, and diesel consumption of surface miner in three different geo-mining conditions. Furthermore, relationships between machine shift-time, pick, and diesel consumption of surface miner and coal production were evaluated through bivariate regression analyses along with their coefficient of determination. These key productivity indicators of surface miner follow polynomial relationships with coal production on a daily and monthly basis, having Pearson correlation values from 0.774 to 0.907 and coefficient of determination, from 0.664 to 0.909 in opencast coal mines.

Jan 20, 2023

By Staff

GENERAL DESCRIPTION The Lucky Friday mine is located in Mullan, Sho-¬shone County, Idaho. The mining method is horizontal slice cut-and-fill (with timbering for support or un¬timbered) using hydraulic sand. Cemented sand fill at a 1:17 ratio is used in sill pours and at a 1:7 ratio for the final 152 mm (6 in.) capping in successive stope floor pours. Annual production with 100% cut-and-fill mining is 167 829 t (185,000 st). The average depth of mining is 1296 m (4250 ft) and the average travel time to the stope is 45 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size The ore body is 396 to 488 m (1300 to 1600 ft) long on strike, 1421 m (4660 ft) on dip, with an average width of 2.3 m (7.5 ft). Dip varies from vertical to1.2 rad (70°) Ground Conditions, Ore Value, and Production Requirements The ore body contains quite strong argentiferous galena and quartz. The hanging wall and footwall are strongly sheared and fractured. Ore value is $211/t ($192/st).

Jan 1, 1982

By M. Fan, R. Letkiewicz, A. Hobert, J. Milbourne

Ultrafine copper, gold and silver minerals flotation has become increasingly important because of the rising demand for processing finely disseminated ores. This paper investigates the improved flotation of ultrafine ores from a Troilus Gold project. Troilus is primarily an Au-Cu deposit but contains minor amounts of Ag, Zn and Pb, as well as traces of Bi, Te, and Mo. As a result of ultrafine Cu-Au-Ag dissemination and associated grinding requirements, Eriez’ column/StackCell and Denver benchtop cells were utilized to optimize their respective flotation responses. Enhanced flotation results were achieved using column and StackCell technologies. KAX 51 and SPRI 206 collectors, Na2SO3, and ZnSO4 depressants were the primary reagents employed. In column/StackCell flotation of three main mineral deposit ore composites, the rougher-scavenger-cleaner circuit Cu, Au and Ag flotation recoveries were 90.4~95.8% at a copper grade of 13.6-17.4%, 87.5-95.1% at a gold grade of 101-145.9 g/t, and 88.6-91.8% at a silver grade of 62.6-251.4 g/t, respectively. The benefits of Eriez Column/StackCell flotation technologies include high flotation selectivity and increased recovery due to unique hydrodynamic designs. Specifically, the StackCell design facilitates high turbulent kinetic energy dissipation rates to improve fine particle recovery and incorporates countercurrent wash water to significantly reduce hydraulic entrainment of the finest size gangue minerals to the froth product.

Feb 1, 2023