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By C. Brown, N. Rayyan, T. H. Dubaniewicz

Lithium-Ion batteries (LIBs) have the potential to go into thermal runaway which introduces a new ignition source in hazardous environments such as gassy underground mines that may contain methane in the surrounding air. Researchers from the National Institute for Occupational Safety and Health (NIOSH) used an accelerating rate calorimeter (ARC) to induce thermal runaway in individual lithium-titanium-oxide (LTO) and lithium-nickel-cobalt-aluminum-oxide (NCA) LIB cells within a sealed enclosure with either no methane, a lean, a stoichiometric, or a rich methane-air mixture in the surrounding canister to determine if these LIB types would ignite the methane, causing an additive effect on overpressures. Canister pressures and maximum temperatures reached by the cells, surrounding air, and exhausted gases were measured in this study and remained consistent with varying methane concentrations.

Feb 1, 2023

By R. Bissonette, C. Sunderman, R. Jacksha

The ability of wireless systems—e.g., voice communication, proximity detection, tele-remote operation, telemetry, etc.—to function satisfactorily (coexist) in the presence of other wireless systems is critical to the safety and health of mine workers. The failure of wireless systems to coexist could result in the delay, corruption, or outright loss, of critical data, voice, or video information. However, no mining-sector-specific regulations, standards, or guidelines exist to ensure the safe coexistence of wireless systems. This paper introduces the concept of wireless coexistence, implications in the mining industry, and the National Institute for Occupational Safety and Health’s (NIOSH’s) research approach to develop guidelines and recommendations to ensure safe wireless coexistence.

Feb 1, 2023

By M. Ribeiro, P. So, P. Wong

Electrowinning is a process by which metals, such as copper or nickel, are recovered from aqueous electrolyte solutions resulting from the extraction of the metal ion from an acidic or basic leach solution. The electrolyte or “pregnant” solution is customarily forwarded to an electrowinning "tankhouse." In the tankhouse, the metal ions are deposited on cathode plates by electrodeposition and then recovered from the cathode plates. Other processes may be employed with other metals, such as nickel, zinc, among others, to produce an electrolyte from which their respective metals are obtained. During the electrowinning (electrodeposition) stage, elemental metal is plated out at the electrowinning cathode and oxygen evolves at an insoluble anode. The evolution of oxygen gas forms bubbles which entrain strong acid electrolyte, carrying it into the air above the electrowinning tank in the form of a fine mist or spray when the bubbles break. An acidic mist is generated above the electrolyte. This mist or spray then spreads throughout the electrowinning tankhouse. The acidic mist is corrosive and a health hazard and can cause extreme discomfort to the skin, eyes, and respiratory systems of tankhouse workers, especially during hot weather conditions. Polyfluoroalkyl based products (PFAS) have been widely applied as anti-misting agents in the electrowinning of metals in an acidic electrolyte. Functionalized PFAS compounds, however, have come under increased scrutiny by the EPA due to their impact on human health and the environment. There remains need for improved acid mist suppression agents for electrolysis and electrodeposition, particularly for products free of fluoroalkyl components.

Feb 1, 2023

By M. Jessop, V. O. Kofoed, R. Blanchard, A. Hughes

Willowstick has successfully employed a new Seismic Acoustic Resonance (SAR) method to improve seepage characterization through, beneath, and around dams. SAR is a passive seismic method that detects zones of higher permeability in the foundation and fill materials of a dam. Just as the ocean has tides, the earth’s crust experiences daily “Earth Tides” and is constantly in motion. Continual motion produces resonance signals that can be measured, interpreted, and modeled to identify zones of higher permeability within a dam and its foundation. The SAR results are analyzed in conjunction with the traditional Willowstick Method to better characterize seepage flow paths and patterns trough, beneath, or around a dam in three dimensions. When both methodologies, which use entirely different scientific principles, identify the same anomalous feature, a higher degree of confidence is gained in the results of the investigation. Willowstick has effectively utilized the SAR method on many successful dam seepage investigations. The two geophysical techniques when used in parallel have yielded complimentary results, with both methods providing beneficial information about seepage locations. This paper will detail seepage flow paths identified using both Willowstick and SAR methods for two case study tailings dams in Canada and the United States.

Feb 1, 2023

By B. Eiter, M. Barham, T. Bauerle

Fatigue-related risk is a persistent safety concern for the mining industry. However, fatigue and sleepiness are often treated interchangeably, which can lead to confusion and potentially less effective reduction of safety risk. To provide clarity, we present an overview of similarities and differences between work-related fatigue risk and sleepiness including definitions, theories, measurements, and mitigation strategies. As a supplement, a summative visual model which highlights these similarities and differences is presented. Expanding industry knowledge in this area will assist safety professionals in crafting more targeted risk management practices appropriate for work-related fatigue risk, sleepiness, or both.

Feb 1, 2023

By D. McElhinney, K. Mohamed, T. Batchler, T. Matthews

Steel props are a type of standing support utilized in coal mines to support mine roof. In addition to the vertical roof loading, sometimes the steel props are subjected to lateral loading of spalled ribs. To enhance the safety of mine workers, the performance characteristics of the steel prop was studied under different scenarios of vertical and lateral loadings. Quik Stik props were used for use in this study. A uniaxial compression loading test was conducted for the Quik Stik prop assembly (inner and outer tubes, ball bearings, collar) to investigate the loading mechanism of the prop. Rupture tests were conducted for the inner and outer steel tubes of the Quik Stik props to estimate the yielding strength of the steel tubes. Nine Quik Stik props of 8-ft high were tested using the Mine Roof Simulator (MRS) at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh research facility. Three props were tested under vertical loading to measure the vertical loading capacity of the props. Six props were tested under lateral loadings with low and high roof-to-floor convergences to measure the lateral loading capacity and the retained vertical loading capacity of the props during lateral loading. Vertical loading tests showed that the tested props could be classified as yieldable supports with a stable load capacity of about 110 kips to 140 kips. Lateral loading tests showed that the vertical load capacities of the tested props were diminished because of applying lateral loads, and the props behaved as nonyielding supports with a maximum lateral load capacity of about 8.5 kips to 9.5 kips at stable lateral displacement up to 3 inches.

Feb 1, 2023

By P. Lopez, E. Wellman, N. Risso, A. Anani

Current machine learning models used for roof fall hazard prediction are mounted on expensive sensors, computationally expensive, or lack the robustness for accurate prediction in the underground mining environment. This research aims to provide a design methodology for a robust, low-cost, deep learning-based algorithm for underground mine roof fall hazard prediction. A data sampling plan is developed to ensure the replicability and robustness of the developed model. In addition, feature engineering and transformation methods are described to identify relevant features for hazard identification. The methodology described here will be used in model development, tested, and implemented as a real-time mobile device application. The new tool will be expected to detect roof fall hazards in real-time and contribute to a crowdsourcing approach for underground hazard detection.

Feb 1, 2023

By Arif Emre Dursun

The aim of this study is to present hazard classifications of location, type, and causes of accidents in Turkish coal-extracting industries using Analytic Hierarchy Process (AHP). In this study, fatal mine accidents were analyzed by pairwise comparison and weighting, and the most important hazards were identified by determining the effective main and sub-criteria among location, type, and causes of accidents. For this purpose, 1st, 2nd, and 3rd level hazards consisting of location, type, and causes of accident were determined by using the data of fatal mine accidents in underground and open-pit coal mining in Turkey between the years of 2010 and 2020. And then the data were categorized, and each category was prioritized using the AHP technique. According to the weights calculated by AHP, the most dangerous main criteria at 1st level hazards in underground coal mining is ventilation operations (0.363), while the most dangerous sub-criterion at 2nd level hazards is firedamp explosions and other gas accidents (0.409). On the other hand, in open-pit coal mining, the most dangerous main criteria at 1st level hazards are slopes and benches (0.575), while the most dangerous sub-criterion at 2nd level hazards are landslides (0.429).

Dec 30, 2023

By VIVEK KUMAR HIMANSHU, Murari Prasad Roy, Kaushik Dey, Rakesh Kumar Singh, Ashish Kumar Vishwakarma

Sublevel stoping is the most popular and practiced mining method in underground hard rock mines. Proper planning and its execution is the key requirement for stope extraction using this method. The stope extraction has been a challenging task since decades. The major reason is the unavailability of free faces as compared to opencast bench blasting. The geological and geotechnical parameters change gradually even within the stope itself. So, the blast design parameters should be planned according to the scenario of the upcoming ring. The blast design parameters like burden, toe spacing, inclination of blastholes, diameter of blastholes, charge density of explosive, etc., play an immense role in the rock damage. For the proper breakage of rock, the movement of burden is the prime objective. To study this, an explicit dynamic based modeler of M/s Ansys was used. The burden values were varied from 20 to 65 times of blasthole diameter to assess the optimum burden value during the study. The models were simulated for the rock having uniaxial compressive strength as 35 MPa and 102 mm blasthole diameter. Three holes were simulated having depth around 14–14.5 m. Different blast design parameters and respective blast-induced ground vibration have also been measured at the experimental site. The core samples of the rock present at the experimental site have been used for the evaluation of geotechnical parameters. These geotechnical parameters were used in the simulation models. The volume of rock excavated along the free face has been calculated in each model by varying the burden. It has been found that the burden value can varies from 35 to 40 times blasthole diameter (3.6–4.1 m) to achieve a greater volume of rock along the free face for 102 mm blasthole diameter and rock of 35 MPa uniaxial compressive strength.

Dec 22, 2023

By Pei‑liang Xu, Jun Wang, Xi Zhang, Deng‑pan Qiao, Tian‑yu Yang

The surface backfill, serving as the operational platform for continuing mining in upward slicing and filling stopes, is required to possess sufficient strength and thickness. Currently, there are limited model methods for determining the strength and thickness of the surface fill body. By analyzing the mechanical actions on the surface backfill, it is determined that its stability is mainly influenced by the combined effects of normal and tangential uniform loads under full-load conditions of trackless equipment. Assuming a circular contact surface between the tire of the trackless equipment and the surface backfill, and utilizing solutions from elastic mechanics theories such as the Boussinesq and Cerruti solution, the stress and displacement distribution of the surface fill body were obtained. Based on the maximum vertical stress condition, where the surface backfill body undergoes maximum deformation while still in an elastic state, and considering the stress–strain relationship, a model for the strength and thickness of the surface backfill has been established. According to the research findings, the design for the strength and structural parameters of the surface backfill has been developed to meet the full-load operation of the Atlas ST7 scooptram, with a compressive strength of 1.32 MPa and a thickness of 0.5 m. Numerical simulation analysis results indicate that the stress and displacement of the surface backfill align with theoretical analysis results. Practical results from industrial application in the western section of the Dahongshan Copper Mine demonstrate that the designed strength and thickness of the surface backfill meet the operational requirements for trackless equipment, resulting in significant engineering application effects and economic benefits. The research findings hold significant importance for advancing the theory of backfill mining and have high applicability and promotional value for similar mines.

Mar 24, 2024

By Martin Langenderfer, Catherine Johnson, Alexander Douglas

Mine haul roads degrade rapidly due to extreme loads on sub-optimal construction materials. Unmanned aerial vehicles (UAV) are suited to quantify large-area road-network conditions, such as surface roughness, defects, and grade to optimize remediation of poor conditions and reduce overall costs. Mine haul roads present unique challenges, such as material type and edge characteristics, to automatic road detection that often fail, requiring manual road input. This research proposes a new method for analysis using the road center determined by principal curve analysis of a haul truck’s Global Navigation Satellite System (GNSS) traces; analysis grids were created from this center line. A dense point cloud from UAV photogrammetry was generated, and multiple linear regression analysis was conducted on each individual grid. The root mean square error in each grid indicates the surface roughness, and the change of slope between grids indicates the road grade inconsistencies. This method was applied to 26 road sections, and the results were validated by images taken from the truck operator’s vantage point. Critical defects were identified including excessive pothole formation, corrugation, depressions retaining water, and narrowing of travel lane. The results demonstrate this is a valid method of road identification and quantification of road defects at a mine site.

Dec 19, 2023

By Christopher Mark

Six decades ago, the most dangerous job in the USA was mining coal underground. Roof falls were responsible for half of the deaths, killing about 100 miners every year. Fast forward to 2016 and zero roof fall fatalities. Just three miners were killed by roof falls during the following 6 years. How did the mining community achieve this historic goal? This paper starts by analyzing the roof fall fatalities in 1968, categorizing them by their fundamental cause. Then, it shows how each type of roof fall was reduced over time, using snapshots of the fatalities occurring in subsequent decades. Along the way, it evaluates the influence of the regulatory environment, changing mining methods, and better ground control technology. The study found that in 1968 more than half of roof fall fatalities at large mines were attributable to an inadequate safety culture. The immediate effect of the 1969 Coal Mine Health and Safety Act was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof Control Plans, which the US Bureau of Mines had been advocating since the 1920s, played a significant role throughout the process.

Mar 12, 2024

By Han Zhao, FENGLIANG WU, Tong Wang

Calibrating an entire mine ventilation network model from survey data has long been considered a challenging and sometimes impractical task. This paper proposes a solution to this issue with the development of a quadratic programming optimization model. The optimization model takes the minimum modification of input resistances as the objective function, uses the mesh pressure equations as equality constraints, and incorporates the lower limits of airway resistances as inequality constraints. A two-step method is developed to solve the model, which includes finding an initial feasible solution and iteratively solving the final solution using the active set method. A computer program has been developed to implement the optimization model. To demonstrate its practicality, a study case using a 35-branch ventilation network is presented, which indicates that the solution process converges after only 57 iterations, a significant improvement over the times of trial and error, which could reach 3.4 × 1010 for the worst-case scenario. Additionally, it is shown that considering only the equality constraints results in negative resistances, while incorporating the lower limits of resistance ensures that the corrected resistances are within a reasonable range. Using the resistance corrected by the optimal model to simulate the ventilation system via traditional methods generates quantities and fan pressures that perfectly match the measured values, eliminating the tedious process of manually adjusting airway resistances repeatedly.

Jan 13, 2024

By Jian Zhou, Shuai Huang, Wenqin Xi, Kun Du

The deep oceans harbor a wide variety of mineral resources that are characterized by their abundance and high quality. Nations worldwide are actively pursuing the exploration and extraction of these resources. This paper provides a concise overview of the mineral resources found in the deep sea, highlighting the challenges associated with their exploitation. Furthermore, it presents a comprehensive analysis of the historical development of deep-sea mining technology and equipment, offering valuable insights into this field. By examining the current issues and obstacles faced in deep-sea mineral extraction, this study concludes that the future of deep-sea mining lies in the direction of automation, intelligence, and standardization. Additionally, it identifies the key technological advancements that need to be achieved in order to overcome the challenges associated with deep-sea mining.

Jan 5, 2024

By Adabala Raja Venkata Sai Naresh, Radhakanta Koner

Particle size distribution (PSD) is an essential parameter in assessing the overall efficiency of blasting operations in mines and the subsequent mine-to-mill process in the mining industry. Despite some drawbacks of 2D image analysis techniques in accurately estimating particle sizes in PSD, the mining industry has relied on them for the last three decades. This study proposes the 3D rock fragmentation measurement (3DFM) technique for deducting the accurate dimensions of 3D rock particles for the PSD. 3DFM has utilized different processing algorithms. Images of different views of the non-touching rock particles of varying sizes have been acquired as a data acquisition step of structure from motion technology for generating sparse point cloud. Dense point cloud reconstruction is used to avail finer details of the point cloud using clustering views for the multi-view stereo algorithm. Random sample consensus (RANSAC) algorithm coupled with an unsupervised classification using the density-based spatial clustering of applications with noise (DBSCAN) classifier is employed to extract the rock clusters from the 3D point cloud. Finally, the accurate rock sizes are derived using the hybrid bounding box rotation identification (HYBBRID) algorithm with a root mean square error (RMSE) of 0.10 cm for length, 0.10 cm for breadth, and 0.32 cm for depth. The PSD of rock fragments obtained from the proposed 3DFM technique is found to be matching with the results of mechanical sieving and manual gauging with an R2 values of 0.98 and 0.99, respectively. The 3DFM method can be considered cheaper, more accurate, and computationally faster in determining the rock dimensions for the PSD determination method to enhance the productivity of the mining industry.

Dec 29, 2023

By N. Duru, C. Nesbitt

During the cyanide leaching process, gold and silver ores that come from the transition zones, which typically contains low levels of sulfide, may produce one or more of the following reduced sulfur species: sulfide ( HS−), polysulfides ( Sn 2−), thiocyanate ( SCN−), thiosulfate ( S2O3 2−), trithionate ( S3O6 2−), tetrathionate ( S4O6 2−), pentathionate ( S5O6 2−), hexathionate ( S6O6 2−). The actual speciation of the reduced sulfur species in the circuits will primarily depend on the redox potential, pH, cyanide levels, and existing sulfur species in recycled process water, as well as the presence of other reactive metal species. The development of an accurate analytical method for sulfur species in cyanide leaching units of gold ores where sulfur speciation occurs has an important role in explaining the metal recovery deviations. This study presents the speciation of sulfur species and the development of ion chromatography method to analyze reduced sulfur species thiocyanate ( SCN−), thiosulfate ( S2O3 2−), trithionate ( S3O6 2−), tetrathionate ( S4O6 2−) in cyanide leaching circuits for gold ores. The method developed has resulted in precise quantification of target sulfur species in leach solutions. Method development and validation results were illustrated on analytical graphs containing each species’ peak number, retention time (min), type, width (min), area (mAU*s), height (mAU), and area distribution (%) of the peak.

Mar 2, 2024

By Abhiram Kumar Verma, Soumya Ranjan Mallick

Generally, waste such as soil and sandstone is used in mines for road construction or haul roads. In many such mines, it is challenging to design haul road pavement to match the dumper capacity. This paper investigates overburden soil to find its utility as a pavement material. It is found that overburden soil is unsuitable pavement material without stabilization; hence, nine composite materials are developed using overburden soil and RBI. Physical, mechanical and microstructural properties of unstabilized and stabilized soil are determined. Statistical analysis is carried out to assess the effect of soil type, RBI and curing period of strength characteristics of unstabilized and stabilized soil. ANOVA tests assess the influence of RBI percentage on soil geotechnical properties, and regression relations are developed. Two-way ANOVA shows the effect of RBI and soil type on soil geotechnical properties, whereas one-way ANOVA shows that the influence of soil type is more than the RBI. The regression relation is developed for CBR, UCS, Poisson’s ratio and modulus of elasticity with a good correlation coefficient. The performance of RBI is more with the finer material and reduces with an increase in the size of soil grains. The performance of the developed composite is better than the earlier developed composite based on overburden with fly ash, lime kiln dust, lime or clinker.

Mar 19, 2024

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"Duluth & Iron Range Railroad. The Duluth & Iron Range Railroad was built from Two Harbors to the Vermilion range at Tower, a distance of 67.6 miles, in 1884, and extended to Ely, twenty-one miles east of Tower, in 1888. It was built into Duluth in 1886, and branches were extended from its main line to the Mesabi mines in 1892 and 1893. The original grades on this road are very steep, going north, and in the thirteen miles from Two Harbors to Highland there is a rise of 1,150 feet. A new line between these points has been built with an increase of three miles in distance and with maximum grades of 1 per cent. Duluth, Missabe & Northern Railway. The Duluth, Mis¬sabe & Northern Railway was constructed from Stony Brook to Mountain Iron, a distance of 48.62 miles, in 1892. The Biwabik branch from Iron Junction to Biwabik, a distance of 15.54 miles, was constructed in 1892. The Superior branch from Wolf to Hibbing, a distance of 16.06 miles, was co11structed in 1893. The Alborn branch from Coleraine Junction to Coleraine, a distance of 53 miles, was constructed in 1906. The total main line mileage is 242 miles, of which 82 miles from Duluth to Hibbing is double tracked"

Jan 1, 1920

By Kwangmin Kim, Junnhyeok Park, Taehee Lee, Minkyu Kim

Mine tailings storage facilities (TSFs) can be a significant source of fine, respirable dust. This dust poses concerns, especially for nearby communities, because of its detrimental impact on respiratory health. To address these concerns, this study examined the effectiveness of commercially available polymers, known for their biocompatible and environmentally friendly features, to prevent dust generation from upstream-type TSFs in active mining operations. It focused on two areas in TSFs: the tailings beach and slope/dike surfaces. Two types of polymers—polyethylene glycol and poloxamer—were selected, and their effectiveness was evaluated in a series of phased laboratory and field tests. The lab tests investigated the moisture-retention capacity of the tailings after treatment with the polymer solutions as well as the ability of these solutions to reduce dust emissions. Polymers were applied to a tailings bed surface in the lab and dust was generated from this surface using a wind tunnel. PM10 and PM2.5 concentrations were measured using laser-diffraction dust sensors, and the polymers were found to have reduced dust emissions up to 95%. Small-scale wind-blowing tests were conducted in the field (specifically, in a controlled environment at a TSF) to evaluate polymer effectiveness on the tailings beach and slope/dike areas. The tests revealed that the AP could efficiently suppress approximately 80% of PM10 and PM2.5 dust emissions at both types of areas. Finally, 1000 gallons of AP solution were discharged at the top of tailings beach and slope/dike areas, respectively, and found to be effective. The results of these tests showed the high potential of the biocompatible polymers to be a feasible solution for reducing the respirable dust emissions from upstream TSFs in arid and semi-arid regions.

By Mark Colwell

As per most other earth science engineering problems, the underground coal geotechnical environment and the way in which roof and rib support interacts with the rock mass are complex issues. While the problem should not be oversimplified (i.e., the dominant failure mechanisms or critical data input parameters should not be ignored), without question judicious simplification is at the heart of all good engineering design. Engineers play a vital role in supplying the world with solutions and products; however it is crucial that engineers make practical and readily useable contributions. One way to ensure this is to employ simplification in the engineering process.