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By Hooman Askari-Nasab, AHLAM MAREMI, EUGENE BEN-AWUAH

In oil sands mining, tailings are voluminous unwanted byproducts generated from extracting the desired mineral from the mined ore. Dyke construction and backfilling activities require well-managed techniques to facilitate progressive reclamation at the earliest opportunity. This directly affects the sustainability and profitability of the mining operation. This research introduces a goal programming framework that simultaneously optimizes the (1) production schedule with limited duration stockpiling and directional mining, (2) dyke construction schedule, (3) size, shape and location of tailing cells and (4) mining and processing production targets. The results show that in creating in-pit tailing-cell designs, decreasing the mining-cell volume and increasing the number of mining cells improves the net present value (NPV) of the operation due to increased operational flexibility.

By Robert L. Chufo

This paper describes a general purpose imaging technology developed by the U.S. Bureau of Mines (USBM) that, when fully implemented, will solve the general problem of "seeing into the earth." A first generation radar coal thickness sensor, the RCTS-1, has been developed and field-tested in both underground and highwall mines. The noncontacting electromagnetic technique uses spatial modulation created by moving a simple sensor antenna in a direction along each axes to be measured while the complex reflection coefficient is measured at multiple frequencies over a two-to-one bandwidth. The antenna motion imparts spatial modulation to the data that enables signal processing to solve the problems of media, target and antenna dispersion. Knowledge of the dielectric constant of the media is not necessary because the electrical properties of the media are determined automatically along with the distance to the target and thickness of each layer of the target. The sensor was developed as a navigation guidance sensor to accurately detect the coal/noncoal interface required for the USBM computer-assisted mining machine program. Other mining applications include the location of rock fractures, water-filled voids, and abandoned gas wells. These hazards can be detected in advance of the mining operation. This initiating technology is being expanded into a full threedimensional (3-D) imaging system that will have applications in both the underground and surface environment.

By Mario A. Terceros Herrera, Mario Terceros Arce, Antonio Marinucci

This paper describes the general principles of the expander body with post-grouting (EBI) system, and how it is similar in nature to a large-scale pressuremeter device. The results from the installation of an EBI can be used to provide information about the stress-strain characteristics of the soil adjacent to the device and to compute estimates of nominal axial resistance. As the EBI expands during grouting, pressure is applied to the in-situ soil surrounding the device thereby compacting/densifying the soil. The nominal axial resistance for small diameter piles/ground anchors can be increased due to the greater soil stiffness and shear strength around the device, larger surface and end area, and improved soil-to-EBI interaction in side resistance. The shape of the response curves depends on the geotechnical conditions of the soil (e.g., in-situ stress state, strength, and stiffness) and the installation method of the piling/ground anchor. This technique has been used successfully with different pile types and ground anchors in a wide range of conditions from very loose sands/silts to very dense sands and medium-dense gravels as well as in soft to stiff clays. This paper also describes a mini case history in which 80 piles were installed to support an office building, and the results of the static axial compression load tests performed on a production FDP+EBI pile is also included.

By Gerald T. Homce, Michael R. Yenchek, H. Kenneth Sacks, James C. Cawley

Accidents occur when least expected, from sources that we rarely anticipate and with outcomes that can vary greatly. Anyone who has ever been involved in an automobile accident knows, the transition from driving comfortably and safely down a highway to being involved in a potentially life-threatening situation can occur in a heartbeat. Accidents on the job are no different. The mining industry has a relatively small number of electrical injuries, compared to industries such as construction or agriculture, due to the small total employment in mining. Mining does, however, have one of the highest occupational electrocution rates of any U.S. industry, at 2.8 for every 100,000 workers per year. This is approximately four times the average for all industries. Data from the Mine Safety and Health Administration (MSHA) shows that 75 electrical fatalities occurred in the mining industry between 1990 and 1999. Of these, at least 17% involved high-reaching mobile equipment that contacted overhead power lines.

By Waddah Akili

At an offshore site along the Red Sea coast of Saudi Arabia, marine structures were supported on tubular steel piles driven into coral and coral contaminated sands and silts. Surprises and disappointments faced during the installation of the piled foundation were, to a large measure, due to inappropriate design methodology and absence of proper soil information. The paper describes the design evolution process, highlights the static pile test program conducted to verify design parameters, and amplifies the need to prepare for worst possible scenario when coral deposits are encountered. Despite corrections made to the design, based on site-specific insitu parameters (skin friction, end bearing) perceived from load tests conducted on site; the final design adopted overestimated capacities in over 50 percent of total piles driven. The paper describes the changes introduced to the design during the execution of the project, highlights the pile test program conducted to verify the design, and compares pile design penetration with actual penetration depth. The unpredictable and erratic pile behavior observed, ascertains the need for more appropriate pile design and installation guidelines for driven piles in coral and coral contaminated formations.

By JIACHENG XIE, XUEWEN WANG, QINGBAO BAO, ZEWEN YAN

The general application of memory cutting technology to shearers is improving the intelligence of the working face, but it has its limitations. It is only suitable for conditions where the environment of coal seam is changing slowly. It compensates for the cutting height by changing the fuselage attitude, and frequently adjusts the height to control the learning cutting trajectory, but due to the problems of shearer control and height adjustment accuracy, it cannot adapt to and compensate for the change of cutting height in a timely manner, resulting in poor cutting accuracy. This study puts forward a virtual memory cutting method based on prediction of the shape of the armored face conveyor (AFC). The integrated key technologies include generation of virtual teaching cutting curve, height adjustment strategy of front and rear drums, cutting

By Daniel Ruffing, Jeffrey Evans

Vertical cutoff, or barrier, walls are an integral part of environmental site remediation efforts. Vertical barriers are commonly deployed to limit the influx of clean ground water and/or to control the off-site migration of contaminated groundwater. The level of detailed design consideration devoted to the vertical cutoff wall component varies widely from project to project and generally decreases with decreasing size and complexity. For those projects receiving minimal design effort, conservative design decisions can lead to unnecessary costs or unanticipated conflicts between the various design considerations. In this paper, the authors discuss several important design and construction aspects of vertical cutoff walls requiring particularly careful consideration during the design phase of the project. These design and construction considerations include the need for and extent of excavation for a key, project target hydraulic conductivity, the use of statistical allowances in the specifications, filter press testing, sand content of in-trench slurry, cleaning of the backfill slope, measurement of stress and strain, the additional of slag in cement-bentonite cutoff walls, and longevity of cutoff walls.

By Braxton P. Erbe, Douglas C. Brunot

A variety of systems and techniques exist to support deep excavations where sloping is not feasible. This paper will explore an example project involving the use of pre-engineered hydraulic bracing systems to support sheet pile walls. Challenges on site that drove the final design include a high water table, irregular excavation geometry, and underground obstructions. The hydraulic system, connected by pins and not requiring welds, allowed for quick deployment and the modularity to change as required due to unforeseen site conditions.

By Doug Scott

Develop tools that companies can use to comply with 29 CFR 1910.1200.

By Sotiris N. Kamenopoulos, Zach Agioutantis

Rare earth elements (REEs) are considered critical minerals for industrial and defense sectors. REEs are not as rare as the word “rare” portrays; yet, the exploitable and/or profitable deposits of REEs may be found only in certain geographical areas. The political and social conditions characterizing these areas may not always be in favor of mining operations. These conditions are imposing the need for extra consideration on the geopolitical constraints prior to any decision-making and before any mining project begins. This study assesses the risk related to mining projects for areas that feature REE deposits based on a geopolitical viewpoint. Probable ranking differences between the current assessment and a 2015 assessment are discussed. The comparative indicators used and the appraisal procedure applied in this comparison are based on a number of different geopolitical indicators. Several ranking changes occurred between 2015 and 2019.

By MANZOOR ALI BROHI, IZHAR MITHAL JISKANI, Atta Ur Rehman, SHUAI HAN, MUHAMMAD TARIQ, NIAZ MUHAMMAD SHAHANI

The analysis of mine safety indicators using a scientific method can improve mine safety and assist management in making informed decisions. This research establishes a mine safety evaluation index and proposes an integrative evaluation model based on the entropy weight and grey clustering methods. The index consists of 27 indicators classified into seven criteria: working environment (A), miners’ attributes (B), safety policies and education (E), prevention and control (F), and monitoring and supervision system (G). Using Pakistan’s mine safety situation as a case study, the proposed model categorized the indicators into five safety levels (very low, low, medium, high, very high) for the present situation and for their relevance in terms of future safety improvement. The results show all of the criteria falling into the very low level for the current mine safety situation. Three of the criteria — C, E and G — are identified as having very high levels of significance for future safety improvements.

By Larissa Koroznikova, Steve Durkin, Bradley Drake, Michael Tuck

This paper presents the results of an investigation of the application of thermal fragmentation in Australian hard-rock, underground, narrow-vein mining. Two geologically similar samples from an underground, narrow-vein, hard-rock gold mine were collected to obtain a measure of the technology’s ability to recover ore by the creation of large thermal openings to assess the applicability of the thermal method.

By Jonathan K. Hrica, Brianna M. Eiter

The ability to identify hazards during a workplace examination is a critical skill for mineworkers to have in order to maintain a safe workplace. While research suggests that being able to successfully recognize hazards requires a complex set of competencies, it is unclear which competencies are most critical to adequately perform a workplace examination. This paper presents a hazard recognition competencies framework as an explanation of the competencies that affect mineworker hazard recognition. To better understand how the industry is selecting and preparing workplace examiners, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) interviewed nine health and safety (H&S) professionals at surface stone, sand and gravel mine sites throughout the United States. These interviews verified that the competencies included in the hazard recognition competencies framework agree with perceptions of the interviewed H&S professionals, who also provided validity for the critical role these competencies play. Finally, the results of this study are presented within the context of current NIOSH research findings related to hazard recognition.

By A. Bhatanagar, D. Makhija, A. K. Mukherjee, R. K. Rath, P. Dixit

Characterization and beneficiation of dry iron ore processing plant reject fines of Khondbond region, India, was investigated. Different characterization techniques viz. size analysis, size-wise chemical and density analysis, X-ray diffraction analysis, sinkfloat analysis, thermo gravimetric analysis, scanning electron microscopy, and QEMSCAN were carried out. Based on characterization results, two process flow sheets comprising wet screening followed by conventional gravity concentration and two stage classification with different beneficiation routes were used to recover the iron values from reject fines containing 58.73% Fe, 5.54% Al2O3, and 6.6% SiO2. Finally, suggested flow sheet comprising of two stage classification and advance gravity concentration followed by the combination of grinding, classification, and froth flotation produced iron concentrate of 2.36% Al2O3 with 75.8% yield which can be used in sinter/pellet making.

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By Jon A. Hummer, MICHAEL R. SHAHAN, Aleksandar D. Bugarski, Shawn Vanderslice

Occupational exposures to respirable dust and submicrometer aerosols emitted by diesel-powered equipment are a health concern for underground mining operators and regulators. A study was conducted in an underground mine with the objective to identify, characterize and source apportion airborne aerosols at the setup face and recovery room during longwall move operations. 

By AKIHIRO YOSHIMURA, HIDEKAZU KATO, KOTA TAKATORI, YASUNARI MATSUNO

Chalcopyrite (CuFeS2) is the most refractory copper mineral when treated in conventional sulfate media leaching systems. This study is the first to examine the use of a dimethyl sulfoxide (CH3SOCH3), or DMSO, solution containing copper chloride (CuCl2) in the leaching of chalcopyrite. The DMSO solution containing CuCl2 could selectively dissolve the valuable metals of copper (Cu) and gold (Au) from chalcopyrite while leaving minerals with little economic value, such as pyrite (FeS2), and the penalty element arsenic (As) in the residues. Leaching chalcopyrite using a DMSO solution that contains CuCl2 offers a number of advantages, including eco-friendliness and easy operation.

By MEHMET KIZIL, PETER KNIGHTS, ROYAL REA

A 1/20 scale experimental dozer push test rig was designed and constructed to quantify the expected production rates (loose cubic meters per hour) for dozers operating in hard-rock bulk push applications. The particle size distribution of the material employed in the test rig was modeled on a fragmented muckpile representative of that for a typical surface copper/gold mine overburden. Buckingham Pi theory was applied to mathematically develop factors for scaling up dozer productivity parameters, including blade loads and push times. Dozer production rates were investigated for various dozing distances and slope angles. A series of instantaneous productivity curves were produced which are applicable for use in hard-rock dozer push operations. The productivity curves produced demonstrate that dozer productivity declines rapidly over the range of 10 to 40 m.

By Mark Colwell

This paper summarizes the results of a research project whose goal was to provide the Australian coal industry with a longwall installation roadway (faceroad) design methodology that could be utilized by suitably qualified colliery personnel. This goal was achieved in 2012 and the design methodology (and software package) is referred to as Analysis and Design of Faceroad Roof Support (ADFRS). The intended benefits to underground operations, in the provision of this information and resource, are a safer and more productive workplace.

By Hesam Dehghani, Farid Alimohammadnia, Nima Babanouri, Mokhtar Kalhori

In open-pit mining, blasting pattern design is performed to achieve a desired degree of fragmentation for loading, hauling, and crushing operations. Inappropriate fragmentation of rock will result in numerous problems such as incurring extra costs for secondary blasting, production interruption, etc. Wetness of the blast holes is one of the most important factors, which can cause the inappropriate rock fragmentation. Lowering ambient temperature in the vicinity of the explosion, the presence of water in the hole adversely affects the quality of the explosive while dissipating part of the explosion energy, ending up with inappropriate fragmentation problems. In the present research, in order to study blast-induced fragmentation conditions in Baba-Ali Iron Ore Mine, three scenarios were considered: explosion of ammonium nitrate with fuel oil (ANFO) in dry hole, explosion of ANFO in wet hole, and explosion of the emulsion in wet hole. For this purpose LS-DYNA, a numerical simulation code was used. Results of the present research showed that, compared to the explosion of ANFO in wet hole, the explosion of the emulsion produced more uniform distribution of fragment size, while the explosion of ANFO in dry hole resulted in fewer large fragments.