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By H. Mischo, F. Daniela, L. Schaarschmidt, I. Paschke

In order to safely store radioactive waste long-term, HAW repositories in saliferous formations have to be backfilled. The main purpose of those backfill operations is the restoration of the geological barrier function of the containment area. For best possible results the used material should be of a comparable composition or characteristic for the host rock formation. Additionally, the material should show a high density after completion of the backfilling process as well as a low permeability. A major aspect to consider in these processes is the minimization of the gap of the backfill body to the roof of the drift. To fulfil those requirements, a micro-structure stabilized crushed salt backfill material has been developed as part of the GESAV-I-project. Due to the material composition of this so-called GESAV-material, salt mineralcrystallization processes start after emplacing it, a process that leads to the polyhalite formation. With the crystallization of polyhalit, the halite grains are bridged, which in return stabilizes the matrix of the backfill. The GESAV-II-project continued successfully what GESAV-I started and determined an ideal backfill method in order to build the backfill bodies composed of GESAV-material. Due to the compaction of the material during emplacement by vibration, high in-situ densities, low permeabilities and a backfill factor close to 1 was able to be reached. In the following SAVER project this journey of practical test underground will be continued.

Mar 2, 2022

By G. Xu, A. R. Kumar, N. A. Amoah

Prolonged exposure to high concentrations of respirable coal mine dust causes coal workers’ pneumoconiosis and silicosis. Underground coal mine roof bolter operators are more prone to elevated exposure to coal and silica dust. The canopy air curtain (CAC) was developed by NIOSH to protect roof bolter operators from the exposure. The CAC supplies filtered air over the breathing zone of the operator. This dilutes the high coal dust concentrations and provides for an impenetrable air curtain. Many studies have been carried out to improve CAC efficiency. However, field test has shown variable dust control efficiencies indicating rooms to further improve due to the nonuniform airflow distribution across the plenum and ineffective perimeter flow. This study therefore redesigns the CAC with optimized flow distribution that effectively protects roof bolters from coal dust exposures. Computational fluid dynamics (CFD) simulations are used to optimize the uniformity of airflow distribution across the plenum to achieve the best possible uniformity. A lab experiment validates the CFD model and confirms the ability of this design to reduce floor dust pickup, prevent external wind infiltration, and offer an improved protection efficiency

Mar 2, 2022

By D. J. Sweet, B. Seymour, T. M. Emery, M. Armatys, J. P. Bourgeois, W. Johnson

The Spokane Mining Research Division (SMRD) of the National Institute for Occupational Safety and Health (NIOSH) has partnered with a narrow vein, hard rock underground mine to research the effects of the binder content on the elasticity and post-peak ductility of cemented hydraulic backfill (CHB). This is part of a larger study to enhance the long-term integrity of ground support in underground mines. As mining advances deeper and stresses increase, CHB mix designs will benefit if they can be modified to handle higher levels of strain which are induced by an increased stope closure, typically affected by a reduction in stope width and increased mining depth, or through dynamic loading resulting from a local seismic event. This portion of the research examined the impact of reductions in binder and their impact on Young’s modulus, peak strength, and post-peak ductility.

Mar 2, 2022

By S. Dixon

The use of warm (40-50°C) solution for the selective elution (pre-strip) of copper cyanide from gold and silver cyanides adsorbed on activated carbon was found to elute +90% of the adsorbed copper compared to the use of ambient (20°C) solution eluting 50-70% of the adsorbed copper. The warm solution pre-strip elution did have higher co-elution of gold (1-4%) and silver (10-18%) with the copper. The use of ambient solution pre-strip elution co-eluted less gold (0.2%) and silver (2%).

Mar 2, 2022

By A. Kalmes, B. Dehler, D. Kopp

Nutrien has six potash mines in Saskatchewan and has been proactive in maintaining the integrity of their tailings facilities through ongoing assessment, design, operation, inspection, and monitoring. Nutrien commissioned a system inventory and semi-quantitative risk analysis (SQRA) of all dikes to further environmental stewardship at their potash facilities. The inventory assessed nearly 100 dikes; each dike was rated according to a probability and consequence factor and assigned a risk score. The risk scores were used to develop a risk matrix for each of the six sites and risk-response actions for each dike and segment. The inventories and SQRAs will help each site assess priorities for investigation and risk mitigation, if necessary. The study results will also help Nutrien refine corporate wide tailings governance standards and demonstrate compliance with various governance regulatory obligations.

Mar 2, 2022

By M. Guzman, S. B. Thais, M. F. Obispo, M. R. Arribasplata

The impact generated by old abandoned mines in Peru have produced mining environmental liabilities, which can generate an impact on the environment. In the search for long-term sustainable solutions, Phytoremediation is presented as an interesting alternative, since it allows the use of Peruvian native plant species for the accumulation of heavy metals. In this paper, we present the results of native high Andean species: Stipa Ichu and Cortaderia Nitida. The final metal concentration in the aerial parts and in the roots of each plant show that Stipa Ichu is more efficient to recover Fe, reaching almost 278 times its initial value. In the same way, this plant is efficient to remove Zn, Cu and Cd, reaching maximum values of 64, 39 and 12 times its initial concentration respectively. Cortaderia Nitida turned out to be more efficient to recover Fe, Zn, Cu and Cr, with highest recovery of 250, 117, 39 and 13 times its initial value respectively. Finally, based on translocation factor, Stipa Ichu has better capacities of hyperaccumulation of Fe, Cu, Zn, Pb and Cr. Cortaderia Nitida only shows hyperaccumulation of Cr.

Mar 2, 2022

By R. Miller

Lowering our globe’s emissions is a major effort as we move toward a future net-zero carbon environment requiring significant investment in a new, low-carbon infrastructure, along with key market incentives to change. Industry will play a key part in this transformation, requiring expertise in both energy and emissions. Key elements of the de-carbonization strategy are: energy data, emissions reporting method, governance, de-carbonization project generation and drivers, the MACC, electrification, and the de-carbonization checklist. For a zero carbon future, it will be key for business leaders to understand decarbonization, anticipate technological changes, and implement new business me

Mar 2, 2022

By M. Ishaq, J. Rosami, J. Brune, E. Sidrow, C. Tsai, S. Slouka

Respirable rock dust poses serious long-term health effects to workers in mining and tunneling underground hard rock environments. When inhaled, respirable silica particles commonly found in quartz and other minerals will scar sensitive lung tissue and cause irreversible lung diseases. Characteristics such as concentration, type of mineral, particle size, and particle shape inhaled can harm workers to various extents. Therefore, this study characterizes rock dust particles less than 100µm in aerodynamic diameter that are released from cutting hard rock in the underground mining environment. In this study, laboratory full scale cutting tests on samples of potash rock were performed with radial picks to generate dust. Three stages of pick wear were tested: new, moderately worn, and severely worn. Comparisons between different stages of pick wear to dust concentration, size distribution, and particle shape characteristics are drawn from this study to start determining the scenarios when the released airborne dusts become potentially most hazardous for workers. Although further testing needs to be conducted to make viable conclusions, the moderately worn pick, or the pick with the most blunt tip, in these experiments are potentially the most dangerous. The blunt pick tip released the highest concentration of dust and generated particle shapes with the highest aspect ratio compared to the other two picks. The preliminary results of this study allow for the further development of optimum bit management and maintenance systems to control the exposure of respirable dust to mine workers.

Mar 2, 2022

By S. Miller, A. Krasner, M. Sizintsev, S. Schafrik, H. -P. Chiu, J. Sottile, A. Rajvanshi, Z. Agioutantis

In recent years, a great deal of effort has been put into automating mining equipment with the goal of improving worker health and safety and increasing mine productivity. Significant progress has been made in automating mining equipment such as load-haul-dumps and drills in underground environments where global positioning systems are unavailable. This paper addresses automating the task of positioning the shuttle-car (SC) under the continuous-miner (CM) coaldischarge conveyor during cutting and loading operations. A stereo depth camera is mounted on the SC. Machine learning based algorithms are applied on the camera’s output to identify the CM discharge conveyor and segment the scene into various regions such as roof, ribs, and personnel. This information is used to plan the shuttle car path to the CM discharge conveyor. The approach currently uses a 1/6th scale continuous miner and shuttle car in an appropriately scaled mock mine

Mar 2, 2022

By P. Moyo, S. Dixon, R. Norcross

The separation and recovery of copper from cyanide solution has been investigated since the early 1900s. The precipitation of copper using sulfide ion was patented in 1911 by Williamson, published by Leaver & Woolf of the USBM in 1931 and Cyanamid in 1960s. The current practice of sulfide precipitation is used in various processes such as “SART" for cyanide regeneration and copper recovery. The precipitation of copper sulfide requires the pH of the clear solution to be in the range of 4-6. The precipitated copper sulfide can be sold to smelters. Alternatively, copper cyanide can be precipitated from clear solutions in the pH range of 2-3. However, selling copper cyanide is challenging because of its cyanide content. Past work has focused on the use of boiling sulfuric acid to convert copper cyanide to copper sulfate as published by Seracini in 1991. This paper describes a simple process to convert copper cyanide to copper oxide using sodium hydroxide at ambient temperatures. The cuprite can be sold to smelters or used as a feed to an electrowinning circuit to produce copper cathodes. The process provides an effective method to recover copper from cyanide solutions with a lower capital requirement.

Mar 2, 2022

By P. A. Cornejo

Blastings always generates induced vibrations through seismic wave, these are lost energy from the blasting and therefore causing the disturbance of slopes and structures near the blast source. Most of the components of an open pit mine have to reach a physical stability, especially during its closure process. Aiming to develop a vibration prediction model using the historical records from an open pit mine located on Peru, this research has two main focuses depending on the distance from the blast source to the structure: to protect the final slopes and to protect the villagers houses. Both are based on the Devine model of the Square Root Scaled Distance (SRSD) to predict the Peak Particle Velocity (PPV). The Mid field model, where is found mainly final slopes from the pit, limited by the failure criteria of McKenzie based on the geo mechanical properties of the rock mass. The Far field model ranges distances where are located the most community households, limited by the German rule DIN 4150 for highly sensitive structures. Both scenarios resulted on a distribution abacus to limit the weight of used explosives to get the best operational advantage and structure safety.

Mar 2, 2022

By M. A. Islam, H. Mischo, G. Barakos

Among the thirty-five declared critical raw materials (CRM) in the United States, there is no sustainable domestic production for the fourteen of them, while for some others domestic supply does not meet the national demand. Numerous potential critical raw material projects are in advanced exploration stages. However, the price uncertainties for many of these commodities put feasible future production into question and come into contrast with overly optimistic price forecasts published in all feasibility studies related to such exploration projects. Thus, in this work, a newly developed smart computational tool is used to evaluate the real perspectives of several CRM exploration projects implementing actual commodity prices, and to conduct reverse calculations in order to find the prices at which each project can be viable.

Mar 2, 2022

By J. Kretschmann, K. van de Loo, J. Brune

In 2018, the German Federal government decided to phase-out the energy production using coal-fired power plants and to terminate lignite mining completely by 2038 at the latest. This decision will impact approximately 60,000 jobs. It will have an enormous impact on the socioeconomic development especially in all German lignite mining regions. To avoid economic and political friction, it is of utmost importance to achieve a sustainable transition towards a post-mining era and to offer residents in the mining districts perspectives for a good future that include adequate job opportunities. In this context, the German government is providing massive structural aids early on. As previous closure experiences from the German hard coal mining industry have shown, it takes at least a generation to overcome the effects of a strategic closing decision of this magnitude. Therefore, the planned closure process appears to be a long time at first glance. In fact, however, it is not.

Mar 2, 2022

By W. Missildine, J. K. Hrica, I. Benbourenane, T. J. Orr, J. L. Bellanca

Each year, haul truck accidents account for a large portion of mining injuries and fatalities. To better understand why these accidents continue to occur, researchers from the National Institute for Occupational Safety and Health (NIOSH) utilized a cognitive task analysis methodology to identify the user requirements of surface haul truck operators and assess differences in perceptions between operators, managers, health and safety professionals, trainers, and maintenance personnel. Additionally, researchers used the critical decision method to focus on better understanding the cognitive demands, decision-making, and problem solving during nonroutine incidents. The preliminary results of this study identify and explore themes within the broad categories of hazards, skills & expertise, and training and provide detailed accounts of nonroutine incidents such as near-misses, loss of control, and collisions. These accounts reveal insights into operator decision making and event progressions that can then be used to build more realistic training scenarios and address hidden hazards and root causes of these incidents. These results, along with potential solutions offered by study participants, can inform future research and help identify creative interventions that can be used by mine operators to address haul truck safety issues

Mar 2, 2022

By W. G. Pariseau

Reliable stress measurement using hollow inclusion gauges and monitoring stress change using borehole stress meters and borehole deformation gauges in anisotropic rock remains a challenge for the rock mechanics community. In this regard, the complex variable method advanced in 1983 for deducing stress in anisotropic rock is flawed and software is privileged. Fortunately, advances in computer hardware and software now enable fast, reliable reduction of hollow inclusion stress measurement data for determining stress in anisotropic rock. Monitoring stress change in anisotropic rock poses a different challenge but is also subject to numerical analysis. Stress measurement using a hollow inclusion (HI) gauge such as the triaxial Australian HI is done in four steps: 1) drilling a measurement hole, 2) installation of an HI, 3) stress relief of the HI by overcoring, and 4) data reduction. The last step, data reduction, is the focus of this work. The process is well-known in linearly elastic, isotropic rock (Worotniki and Walton 1976, Duncan Fama and Pender 1980). However, in case of linearly elastic, anisotropic rock the requisite technology is not readily available. This situation is somewhat surprising because anisotropy is more often the rule rather than the exception, especially in the neighborhood of ore bodies. Rahn (1984) has pointed out the potential for significant errors with neglect of anisotropy and the adverse consequences for engineering design. Amadei (1984) has also pointed out the potential for errors with neglect of anisotropic rock properties in stress measurement. Worotniki (1993) cites other studies that indicate potential for serious errors when doing measurements in anisotropic rock. In both theoretical cases (isotropy and anisotropy), data reduction is essentially a composite of solutions to boundary value problems in linear elasticity. In the finite element approach, the analysis is a simulation of gauge hole drilling, installation and overcoring. Two important advantages with the finite element approach are a more faithful representation of the conditions of HI stress measurement than approximated in theory and the capability for handling rock whether isotropic, transversely isotropic or fully anisotropic

Mar 2, 2022

By N. Rocco, G. Johnson

Implementation of post-closure draindown estimates for tailings facilities are important predictive tools for reclamation planning and often influence jurisdictional bonding. Simplified estimates of draindown have been proposed in the past but these methods are not able to capture many of the site-specific nuances as well as operational and material parameters that influence robust draindown estimates. This paper discusses an iterative approach that relies on unsaturated flow models to predict draindown rates and associated pond inventory water balances that track inputs into underdrain pond systems, solution storage volumes, implementation of active evaporation, and necessary recirculation of solution back to the tailings facilities. Specific design criteria such as climate, facility geometry, material properties, and initial conditions, as well as active closure operational considerations that can influence draindown estimate will be discussed. Concepts presented will be valuable for operators, designers, and regulators to guide closure planning and predictive analytical analyses that support draindown estimates.

Mar 2, 2022

By E. Gutierrez, P. Gillies

Asset Maintenance Readiness (AMR) provides a tailored reliability and maintenance strategy specific to operational needs. AMR delivers reliability and maintenance foundations for the plant and equipment before start-up. Having a dependable reliability and maintenance strategy before start-up is critical, particularly in those first weeks and months during ramp up to stable production. The Asset Maintenance Readiness is the integration of Reliability and Maintenance Engineering analysis/studies at the earliest stages of the new Production System concept and design and during the Capital Project CapEx phases; adding this analysis to the Capital Project CAPEX cost, will have an impact of 2% to 3% of total project cost, but will deliver a good compendium of benefits far from the AMR costs, and those results will be shown upon commissioning and during the life cycle of the plant.

Mar 2, 2022

By R. Kealey, D. Huo, Q. Zhang, Y. A. Sari

Greenhouse gas (GHG) emissions from primary mineral and metal production account for ~10% of global GHG emissions. One of the main sources of GHG emissions in mining operations is fuel consumption by haul trucks. Given their size and carrying capacity, the fuel consumption of haul trucks can approach 250 liters per hour. An average of 30% of the idle time of the trucks is spent while waiting in the queue. Inefficient truck dispatch planning can waste resources, cause dilution and elevate GHG emissions. In this research, a machine learning based truck dispatch approach was developed to dynamically route the haul trucks based on the loaded material, the road traffic, the estimated wait time, and the maintenance needs of the trucks. The GHG reduction potential of this smart fleet management approach was estimated by calculating and comparing the related carbon emissions versus scenarios using traditional fleet allocation approaches. Results suggest that this dynamic fleet allocation approach can significantly reduce GHG emissions at mineral production sites by optimizing waiting times and the overall distance travelled while achieving the same production levels.

Mar 2, 2022

By E. Watkins, S. J. Schatzel, V. Gangrade, R. Kimutis, J. Addis, C. Hollerich

The recent shale gas revolution in the United States has led to the drilling of hundreds of unconventional shale gas wells in active and future coal reserves in traditional coal-mining regions of Pennsylvania, West Virginia, and Ohio. This paper summarizes the impact of a shale gas well breach on the mine ventilation system of an operating longwall panel. This study utilizes a 1:30 scaled Longwall Instrumented Aerodynamic Model (LIAM) to simulate a single-panel longwall operation. The LIAM will be utilized to identify flow pathways and distribution patterns of gas from breached gas well scenarios in an operating longwall in the Pittsburgh Coal Seam. Sulfur hexafluoride (SF6) tracer gas is utilized to simulate a breached gas well. Preliminary findings suggest that the breached gas is diluted to regulatory levels and does not accumulate in the mine entries or in the longwall gob when the longwall panel is adequately ventilated. Overall, this study characterizes the potential interaction between shale gas wells and the mine environment in the event of a gas well breach, which provides critical information to the industry and regulatory agencies for improving safety, health, and welfare of miners.

Mar 2, 2022

By F. Sime, X. Wang, J. D. Miller, T. Akinseye, S. Assemi, L. Pan

Respirable coal mine dust (RCMD) is a complex mixture of carbonaceous and mineral particles with a variation in size and shape. Accumulation of RCMD in the lungs of underground coal miners results in severe respiratory damage and ultimately progressive pneumoconiosis known as the black lung disease. The occurrence of the black lung disease dropped to a low of 2.1% in 1990s but has increased to 3.1% in 2000s [1], prompting more research on coal mine dust mitigation. In addition to surveying the impact of new mining technologies on the size of generated dust and exposure measurement, a comprehensive characterization of physico-chemical properties of RCMD particles are essential for a better understanding of the adverse health effects of coal mine dust. Such vital factors include particle size, surface charge, morphology, composition, and agglomeration state. The respirable fraction of RCMD, has been designated as particles < 10 μm in diameter, and almost all studies on the RCMD toxicity have focused on micron-sized particles. However, recent toxicological studies have shown that nanoparticles (particles with one dimension less than 100 nm) can have a magnified toxicity compared to the larger particles with the same chemistry [2]. Nanoparticles have a much higher specific surface area compared to the same mass of larger particles and are thus more reactive. Most micron-size particles can be cleared by the body’s defense mechanism. However, inhaled nanoparticles can easily deposit in all regions of the respiratory tract and can translocate to vital organs. [2].

Mar 2, 2022