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By John Thella, Edward McNew, Christina Thella, Mends Emmanuel, Pengbo Chu

Ore sorting is an emerging technology in mineral processing that can produce a significant impact on the total mining and processing economics. The technology is capable of preconcentrating an ore based on differences in the mineralogical characteristics, which can include color, brightness, transparency, size, shape, density or near-infrared response. The current practice of conducting an ore sorting test typically requires large amounts of materials to be sent to a commercial testing facility, which is expensive and time-consuming. Here, we present a novel method to simulate commercial ore sorting on a laboratory scale using a rare earth ore.

Jan 1, 2025

By Alper Kirmaci, Taghi Sherizadeh, Gunnar Wurst, Paul Brooks, Dogukan Guner, Samuel Nowak, Mina Esmaeelpour, Kutay Karadeniz

As mines continue to deepen and become more expansive, active monitoring of larger volumes of rock mass will become more critical to calibrate numerical simulations and to ensure the safety of underground workers. Monitoring larger volumes of rock mass requires low-cost sensors that are simple in construction and installation. In this study, a novel hybrid optical fiber cable (HOFC) designed for use in distributed optical fiber sensing (DOFS) via grouted boreholes was deployed to monitor a bulk mining operation in an underground metal mine. The HOFC was successfully used to monitor approximately 2.7 × 10 m3 of rock mass above excavations surrounding a pillar removal area in which six large pillars were removed simultaneously. A total of six measurement boreholes (maximum depth of 22 m) were used to measure strain along the optical fiber during the pillar removal operation using the HOFC, allowing for 70 individual strain measurement points, which were constructed for under one U.S. dollar each. Monitoring of the excavation area took place over a 44-day period after pillar removal. Extensional strains were noted in the areas closest to the removed pillars, while areas of compression were noted directly above the remaining pillar in the area. The results of the case study demonstrate that a low-cost optical fiber strain sensing network can be rapidly installed in a large excavation area and can provide highly sensitive strain measurements in a manner that would be cost prohibitive using other methods.

Oct 1, 2024

By Brendan Donnelly, Jung-Hoon Sul, Lasitha Piyathilaka, Sanghyun Jeong, Benjamin Probyn

The chains of armored face conveyor (AFCs) are constantly in contact with water and wet coal, which results in a significant proportion of unplanned downtime experienced on longwall equipment due to corrosion. While reverse osmosis (RO) is one of the most prevalent water treatment methods for reducing salinity and dissolved solids in coal mining, its impact on the corrosion of the AFC chains has not been well studied. This work studies the direct effects of RO water on the corrosion of AFC chains. Immersion tests followed by surface micromorphology analysis and corrosion indices indicate that the RO water increased the corrosion rate of the AFC chains due to the reduced tendency of preventive films on the chains.

May 1, 2024

By Elif Emil-Kaya, Bernd Friedrich, Merve Papakci

Samarium (Sm), one of the rare earth elements (REEs), and cobalt (Co) are used in the production of SmCo permanent magnets, which have excellent temperature stability, corrosion resistance and oxidation resistance. Of the two types of SmCo magnets, one contains a high amount of iron, approximately 15.2 percent. This paper focuses on the recycling of iron (Fe)-bearing SmCo. In this study, an oxidative leaching process with nitric acid was developed to eliminate iron through in situ hydrolysis and to dissolve REEs and Co. The influence of experimental conditions on the formation of an amorphous iron compound through the hydrolysis of Fe3+ in a nitric acid environment was thoroughly examined based on a Taguchi orthogonal array. The optimal parameters for oxidative leaching were determined to be an acid concentration of 3 mol/L, a solid-to-liquid ratio of 1/10, and a process temperature of 60 °C.

Jul 1, 2024

By ERIK CHARRIER, ADITYA JUGANDA, Jürgen Brune, Gregory Bogin, Patrick Maier

Confined explosions are a major risk in underground coal mine operations. Depending on confinement, ignition location and obstacles in the flame path, methane explosions can transition to detonations. This research focuses on explosion experiments in a reactor with diameter of 71 cm and length of 30.5 m, along with developing the corresponding computational fluid dynamics (CFD) model that captures the observed flame behavior. The results show that the 2D and 3D CFD models are able predict the experimental flame front propagation velocity, but the 3D model shows more explicit conformity than the 2D model.

May 1, 2024

By Jaeheon Lee, Junmo Ahn, Jiajia Wu

To reduce the environmental footprint of hydrometallurgical processing of black mass from spent lithium-ion batteries (LIBs), a green leaching system based on glycine and sodium metabisulfite (Gly-SMS) was proposed. The leaching study demonstrated that the highest cobalt and lithium recoveries of 100 percent and 99.8 percent were achieved under optimal conditions. The leaching mechanism revealed that the dissolution of LiCoO2 in the Gly-SMS solution followed the shrinking core model. The apparent activation energies for cobalt and lithium were determined as 48.05 and 41.51 kJ/mol, respectively, indicating a surface chemical reaction controlling mechanism. The leachate was then processed by an acidification- precipitation technique with oxalic acid as the precipitant to remove cobalt. Glycine complexes with metal ions by zwitterionic ligand and recycles in the leaching-precipitation circuit, reducing the reagent cost. Compared to other studies, this leaching system has near-neutral operating conditions and is cost-effective, making it an economically viable alternative for treating cathode materials from spent LIBs.

Dec 1, 2024

By Arif Emre Dursun

The aim of this study is to present hazard classifications of location, type and causes of accidents in the Turkish coal-extracting industry using the 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, first-, second- and third-level hazards consisting of location, type and causes of accident were determined by using the data of fatal mine accidents in underground and openpit coal mining in Turkey between 2010 and 2020.

May 1, 2024

By Isabel Barton

This article describes and analyzes the history of research into the origins of the uranium-vanadium(-radium) deposits of the Paradox Basin. For several decades after their discovery in 1881, research was desultory and almost entirely descriptive, fluctuating with demand for vanadium and radium. Systematic geologic descriptions, accumulated between 1910 and 1950, supported rapid progress during a government-backed surge of research in the 1950s, when uranium was the chief commodity of interest. Most of the major theoretical innovations date from this decade, including the use of concepts from solution chemistry to identify the conditions and constrain the processes of deposit formation and alteration. Research from this time was highly influential in geology at large, providing the model for sandstone-hosted uranium deposits worldwide and numerous new minerals and mineral structures. After about 1960, mine production remained high but research dwindled, and most new advances were to the details of the hydrothermal model of ore formation rather than its core concepts. By the end of the 1960s, the deposits were understood to have formed at the mixing interface of an oxidized, metal-bearing water with a reducing fluid of debated origin. Research was desultory over the ensuing decades; the source of the metals and the nature of the chemicals constituting the trap were not clearly established. They remain questions today, as do factors like the relationship between ore mineralization and the geologic history of the basin. (More in the full paper.)

Jan 1, 2025

By Firat Atalay

Estimating the spatial distribution of ore grade is one of the most critical steps to proceed with an investment decision on a deposit. Kriging is the most widely used method to estimate the ore grade, but alternative techniques are being developed. Machine learning algorithms can be used as alternative methods to classical kriging. In this paper, the iron (Fe) grade of a deposit is estimated with the XGBoost algorithm, and the results are compared with kriging estimation results. For the estimations, samples collected from drillholes were used. Due to the different natures of the estimation methods, different steps were taken to perform the estimations. The results show that XGBoost produced higher-range estimates, which is a desired result in ore grade estimation, and the minimum and maximum of the estimates were lower and higher than the kriging estimates, respectively. However, like kriging, the estimation results were smoother than composites, and the variance of the XGBoost estimates was lower than the variance of composites. This means that even though estimation with XGBoost mitigates the smoothing effect, the estimation results suffer from smoothing like kriging.

Dec 1, 2024

By Amy McBrayer, Vladislav Kecojevic, Juan David Valencia Quiceno, Dragan Bogunovic

The mining industry’s commitment to innovation reflects a history of adopting technological advancements to enhance workplace safety, environmental sustainability and vocational training. The objective of this research was to develop an augmented- reality (AR) system for heavy-equipment operators (HEOs) in surface mining. The developed system has the potential to enhance mine safety, training and data-driven decision- making, which presents a significant step toward a more sustainable, effective and technologically driven mining training, contributing to the industry’s evolution and growth. The AR training system leverages Microsoft’s Power Platform and HoloLens 2 capacities to provide operators with detailed and immersive training guides for three mining equipment, including bulldozers, motor graders and haul trucks. AR guides combine speech controls, 3D objects, informative images and explicative videos in the real working conditions to enhance the operator’s learning process. The system has the potential to modify the training structure based on user performance and provides an efficient approach to data collection during training. This project was developed and applied through a case study in a surface mine in the Southern United States.

Feb 1, 2025

By C. Nesbit, N. Duru

During the cyanide leaching process of gold and silver, ores that come from the transition zones which typically con-tains low levels of sulfide may produce one or more of the following reduced sulfur species: sulfide (HS ), polysulfides (Sn ), thiocyanate (SCN ), thiosulfate (S2O3 ), trithionate (S3O6 ), tetrathionate (S4O6 ), pentathionate (S5O6 ) and hexathionate (S6O6 ). The actual speciation of the reduced sulfur species in the circuits will primarily depend on the re-dox potential, pH, cyanide levels and existing sulfur species in recycled process water, as well as the presence of other reac-tive metal species. Development of an accurate analytical method for sul-fur species in cyanide leaching units of gold ores where sul-fur speciation occurs has an important role in explaining the metal recovery deviations. This study presents the speciation of sulfur species and development of an ion chromatography method to analyze the reduced sulfur species thiocyanate, thio-sulfate, trithionate and tetrathionate in cyanide leaching circuits for gold ores. The method developed has resulted in the precise quantification of target sulfur species in leach solutions.

Jun 1, 2024

By G. Frey, D. Scott, C. Pritchard

Controlled recirculation has been used in the metal/nonmetal mining industry for energy savings when heating and cooling air, in undersea mining and for increasing airflow to mining areas. For safe and effective use of controlled district recirculation, adequate airflow to dilute contaminants must exist prior to implementation, ventilation circuit parameters must be accurately quantified, ventilation network modeling must be up to date, emergency planning scenarios must be performed and effective monitoring and control systems must be installed and used. Safety and health issues that must be considered and may be improved through the use of controlled district recirculation include blasting fumes, dust, diesel emissions, radon and contaminants from mine fires. Controlled recirculation methods are expected to become more widely used as mines reach greater working depths, requiring that these health and safety issues be well understood. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted two controlled recirculation tests over three days at a Wyoming trona mine, utilizing an inline booster fan to improve airflow to a remote and difficult-to-ventilate development section. Test results were used to determine the effect that recirculation had on air qualities and quantities measured in that section and in other adjacent areas. Pre-test conditions, including ventilation quantities and pressures, were modeled using VnetPC. During each test, ventilation quantities and pressures were measured, as well as levels of total dust. Sulfur hexafluoride (SF6) tracer gas was used to simulate a mine contaminant to monitor recirculation wave cycles. Results showed good correlation between the model results and measured values for airflows, pressure differentials, tracer gas arrival times, mine gasses and dust levels.

Jan 1, 2013

By Chee S. Theng

As the 2017 president of the Society for Mining, Metallurgy & Exploration Inc., I am pleased to present the 2017 issue of the Transactions of the Society for Mining, Metallurgy & Exploration Inc., Vol. 342. A significant portion of the contribution that we make as a professional society is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of the American Institute of Mining, Metallurgical and Petroleum Engineers (AIME). Those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2017 Transactions contains some of the most interesting research and insights from the past year and features an international slate of authors spanning industry, academia and government. Papers include the latest findings from the U.S. National Institute for Occupational Safety and Health (NIOSH), a special review article on Heap Leach Modeling, and articles from two Special Issues on Rare Earths. The 2017 Transactions consists of a total of 54 technical papers, encompassing all 21 papers published in 2017 in the Technical Papers Section of Mining Engineering (Vol. 69) and all 24 papers published in 2017 in Minerals & Metallurgical Processing (Vol. 34). Additionally, this volume contains 9 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All of the technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our Publications staff. As the 2017 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume.

Jan 1, 2017

By Changshou Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,175 t (3,500 st) of ore per day with an average gold grade of 12.6 g/t (0.4 opst). The mine has a large horizontal extent of 762 by 152 m (2,500 by 500 ft) and a vertical extent of 6 to 61 m (20 to 200 ft). Based on the characteristics of the ore bodies, the deposits are divided into several mining zones. The geotechnical properties of mining zones are also different from one zone to another. A successful geotechnical collection system is very important for mining design and operation in the Leeville underground mine. Three methods are used to collect the geotechnical data in the Leeville underground mine: • Core logging. Most geotechnical data are collected by this method, which is based on exploratory drills and estimates parameters for rock quality designation (RQD), fracture frequency (FF), compressive strength and rock mass rate (RMR). • Site investigation. This method collects more detailed geotechnical data and geostructural data from work done in the underground drifts and stopes. Parameters of RQD, FF, compressive strength, RMR, rock tunneling quality index (Q) and geostructural data are estimated. • Data collected from drill holes made for the critical infrastructure facilities. This method provides the best detailed geotechnical information for areas in which the critical infrastructure located. A complete geotechnical database has been constructed using this geotechnical data collection system. The database can be used for the design of ground support, stopes and stope blasts, among other critical applications.

Jan 1, 2010

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 J. Kemeny, K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in an area of the mine that contains argillite and is relatively homogeneous. This process also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for argillite will be updated as more tests are conducted, and the model will be extended to the four other primary rock types at the Asarco Mission mine.

Jan 1, 2011

By T. W. Beck, J. A. Organiscak

The U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) has recently studied several redirected scrubber discharge configurations in its full-scale continuous miner gallery for both dust and gas control when using an exhaust face ventilation system. Dust and gas measurements around the continuous mining machine in the laboratory showed that the conventional scrubber discharge directed outby the face with a 12.2-m (40-ft) exhaust curtain setback appeared to be one of the better configurations for controlling dust and gas. Redirecting all the air toward the face equally up both sides of the machine increased the dust and gas concentrations around the machine. When all of the air was redirected toward the face on the off-curtain side of the machine, gas accumulations tended to be reduced at the face, at the expense of increased dust levels in the return and on the curtain side of the mining machine. A 6.1-m (20-ft) exhaust curtain setback without the scrubber operating resulted in the lowest dust levels around the continuous mining machine, but this configuration resulted in some of the highest levels of dust in the return and gas on the off-curtain side of the mining face. Two field studies showed some similarities to the laboratory findings, with elevated dust levels at the rear corners of the continuous miner when all of the scrubber exhaust was redirected toward the face either up the off-tubing side or equally up both sides of the mining machine.

Jan 1, 2013

By R. Heiser, J. Vendetti, B. P. Connor, E. J. Haas

Health and safety indicators help mine sites predict the likelihood of an event, advance initiatives to control risks, and track progress. Although useful to encourage individuals within the mining companies to work together to identify such indicators, executing risk assessments comes with challenges. Specifically, varying or inaccurate perceptions of risk, in addition to trust and buy-in of a risk management system, contribute to inconsistent levels of participation in risk programs. This paper focuses on one trona mine’s experience in the development and implementation of a field-level risk assessment program to help its organization understand and manage risk to an acceptable level. Through a transformational process of ongoing leadership development, support and communication, Solvay Green River fostered a culture grounded in risk assessment, safety interactions and hazard correction. The application of consistent risk assessment tools was critical to create a participatory workforce that not only talks about safety but actively identifies factors that contribute to hazards and potential incidents. In this paper, reflecting on the mine’s previous process of risk-assessment implementation provides examples of likely barriers that sites may encounter when trying to document and manage risks, as well as a variety of mini case examples that showcase how the organization worked through these barriers to facilitate the identification of leading indicators to ultimately reduce incidents.

Jan 1, 2017

By Yi Luo

Subsidence events occurring above inactive room-and-pillar (R&P) mines, including abandoned mines or sealed portions of active mines, are classified as unplanned subsidence, because of their timing and distribution are unpredictable. When investigating such subsidence cases, many uncertainties exist and disputes often focused on whether the observed structural damages are caused by mine subsidence or other natural or artificial causes. However, solid evidence to identify the cause is often lacking. In order to conduct a complete and impartial investigation, thorough knowledge of subsidence theories and other ground control topics, as well as broad experience, are required.

Jan 1, 2011

By J. F. Burr, D. Snyder, W. Calder

This paper provides a determination of the equivalent level of protection of the international standards relative to similar criteria used by the U.S. Mine Safety and Health Administration (MSHA) to approve two-fault intrinsically safe (IS) stand-alone equipment. U.S. mining law requires such a determination for MSHA to use alternatives to existing standards. The primary issue is to demonstrate that the international standards for equipment evaluation will provide at least the same level of protection for miners as the document currently used by MSHA.

Jan 1, 2017