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By J. Kretschmann, P. Goerke-Mallet, C. Melchers

Mining always leaves a mark behind. Dealing with this legacy is not only a tremendous challenge in Germany, but internationally too. The Technical University Georg Agricola (THGA) in Bochum, Germany, has established a Research Center for Post-Mining. Researchers combine expertise from a variety of technical and nontechnical fields in their quest to shape the post-mining era that completes the mine life cycle. In this respect, the Research Center focuses on four research areas: Perpetual tasks and mine water management, Geomonitoring, Material sciences and site transition. With more than 200 years of successful partnership with the mining industry in Germany and abroad, THGA offers a perfect setting for fresh and sound ideas in order support mining’s social license to operate. The aim of the paper is to describe the Post-Mining Research Center along with exemplary research projects that are of interest to the mining industry globally and to foster technical communication and research networking.

Mar 2, 2022

By A. Bascetin

It was recently proposed to use the pastefill technology as a surface tailings management method. Surface paste is an economic and safe storage method that respects current environmental regulations. There are many problems related to accidents that occur in conventional tailings damps. In this study, the applicability of the surface paste disposal (SPD) method for a Pb-Zn mine in western Turkey was examined. Density was 3.084 and specific surface area was 0.899 m2/g. The mill tailings have very low plasticity and show characteristics of clays and silts in terms of the Unified Soil Classification System. The particle size distribution of the tailings was 39.2% particles finer than 20 µm. The results of this study showed that the physical and chemical properties of mill tailings make them suitable for SPD.

Feb 23, 2014

By Godfred Amponsah, Mehrdad Razavi

Slope failures very commonly occur during a long period of heavy rainfall and groundwater rise. The failures pose a substantial risk to people, infrastructure, and equipment downslope. In the recent past, the mining industry has faced an increase in tailings dam failure due to several reasons including pore pressure increases in the dams. Many failures have been observed to occur during times of water level fluctuations but the critical factors that influence the initiation of slope failures still need to be adequately clarified. To investigate these factors, laboratory experiments were conducted on model sandy slopes to determine pore pressure-induced slope failure initiation. This study also presents a method to examine water seepage through soil slopes using an ultraviolet (UV) dye and a UV flashlight. The small-scale model test simulation demonstrated failures induced by either water percolation from the upslope tank at a constant level or by raising the water level at intervals. A bottom chamber fully filled with water to replicate groundwater rise was also simulated. The soil slope was monitored at every stage to study the deformations and behavior until failure occurred. Results gathered from the controlled laboratory conditions were useful for the verification of the numerical modeling method created in the computer program Slide. The analysis showed that slope failure always occurred when the toe was fully saturated. High pore pressures and seepage forces reduce the shear force at the toe to almost zero causing it to slide. A comparison of slope height to water level also indicated an average of 96% water level to cause a failure. At this point, the soil slope is fully saturated and has no matric suction. The findings in this study show that, by monitoring the moisture content of slopes, failures can be predicted.

Feb 1, 2024

By Eduardo Pimenta de Melo, Rambabu Pothina, Rajive Ganguli

Sensors are everywhere in the mining industry, with sensor information being used to monitor and operate processes. Therefore, when sensor information is wrong, economic losses can occur. Unfortunately, sensor errors are usually not detected till they become large. This is problematic as most calibrate their sensors no more than once a year (Beamex, n.d.). Using principles of data mining, where all relevant information is tapped to glean hidden information, Pothina [8] designed an algorithm to detect errors in temperature sensors in gold stripping circuit in Pogo mine, Alaska. This paper continued his work by analyzing the behavior of the algorithm on baseline data and testing the algorithm in new data and under more rigorous conditions. It also made a change to the algorithm. The modified algorithm performed very well in the new data. It also worked well under the new error conditions. Three types of errors were seeded, a fixed additive error (+ 2%), a fixed subtractive error (− 2%), and a noisy, normally distributed error, with a mean value of + 2%. Artificially seeded errors were detected within about 20 gold stripping cycles. Inherent bias in operation impacted algorithm performance by increasing the number of cycles needed to detect errors. This paper reinforced Pothina’s [8] conclusion that when data mining approach is used, sensor errors can be detected even when they are pretty low. Significant economic losses can thus be minimized.

By J. E. Gebhardt, D. W. Fuerstenau

The use of small quantities of polyacrylic acid (PAA) was found to significantly improve the flotation of fine-sized hematite particles at pH 4.1 and 0.001 M NaCl with sodium dodecykulfonate (SDS). Low polymer dosages before collector addition aid flotation by forming flocs of primary particles, but excess polymer results in low flotation yields due to surface saturation by the hydrophilic polymer. Contact angles, measured on a hematite disk, substantiate the hydrophilic nature of an adsorbed polymer film. Pre-adsorbed PAA reduces the amount of SDS adsorbed on the hematite particles, but the flotation of hematite flocs occurs, even at reduced amounts of adsorbed SDS, and is not depressed until PAA dosages in excess of the saturation value are used. Separation of a hematite-quartz mixture can be achieved by SDS flotation of PAA,-flocculated hematite. Maximum selectivity results with the addition of small quantities of PAA, while excess polymer is detrimental to the recovery of hematite. Consecutive flotation states on a single feed yield a higher grade hematite product at some expense to the overall recovery.

Jan 1, 1987

By K. L. Gabby

Since mercury is chemically similar to silver, it tends to dissolve along with the silver and gold during cyanide leaching. Ultimately mercury is recovered along with the silver as mercury/silver/gold amalgam which requires retorting to remove the mercury prior to refining the silver and gold. A possible approach to separating mercury from silver and gold in cyanide leach solutions is to take advantage of the replacement reaction between [Hg(CN)4]2- and Ag2S, which results in precipitation of mercury as HgS while dissolving silver as [Ag(CN)2]-. Results are presented demonstrating that mercury can be removed from cyanide solutions with high effectiveness, while, at the same time, recovering additional silver in solution. Initial experiments with static flasks in the laboratory showed a high degree of mercury removal could be achieved. Results using actual metallurgical plant products in bottle roll tests indicate the process works on a larger scale, but also results in significant gold losses if the solution being treated has high gold levels, such as carbon stripping pregnant eluent solution.

Feb 23, 2014

By P. R. Pereira

This paper presents a comparison between the simulations of a semi-empirical model and a theoretical model for the prediction of radial stress in rock. The results of the simulations were compared to the results of a field test. The comparison of the radial stress predictions shows that in the semi-empirical model use of the plane wave approximation as the basis for the prediction of the radial stress provides a much better result than the theoretical model. The theoretical model includes the correct elastic wave geometry and theory but fails twice, firstly by considering the charge as a point (unit) energy source therefore; and secondly by using a Delta function with a very sharp rise and decay time to simulate, with no distinction between non-linear and linear zones, the attenuation of the energy per unit volume at the shock wave front as the wave moves away from the borehole. The results of the semi-empirical model were within the same order of magnitude as the results from the field test whereas only one result from the theoretical model came close to the result of the field test. However, even this closer result for the theoretical should be taken with caution as there was no measurement in the field test made at this distance from the borehole. Finally, because of its potential portability, convenience, and cost-effectiveness the theoretical model can be a most valuable tool for mining and civil construction operators in the early design of blasting rounds and of the mining operation itself.

Jan 1, 1993

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi

The abstract highlights the impact of flocculants used in the middle thickener of a copper-molybdenum plant on both process water quality and molybdenite floatability. The study investigates the effect of a starch-based flocculant (wheat starch) on the efficiency of the middle thickener and molybdenite flotation. The findings indicate that the presence of starch influences the settling behavior of particles with different shapes, and the dosage of starch affects both molybdenum recovery and the presence of copper minerals in the molybdenum concentrate.

Mar 7, 2022

By S. K. Kawatra, J. A. Halt

"Low-grade iron ores are finely ground and processed to recover iron-bearing minerals. However, the iron-rich powder is too fine to be used directly in blast furnaces and most direct reduction furnaces, and must be agglomerated or pelletized into a usable product called “pellets.” Bentonite clay has traditionally been used as a binder to make iron ore concentrate pellets, but it is expensive and contaminates the pellets. Organic binders may be a viable alternative to bentonite clay. This manuscript reviews organic materials that have been used to make iron ore concentrate pellets. Included are discussions on the development of organic binders, common pros and cons to organic binder use, organic binder structure and its effects on agglomeration, and additives to organic binders.IntroductionIron ore agglomeration turns finely disseminated, low-grade iron ores into a usable product, called pellets. During pellet production, fine-grained, iron-rich minerals are liberated from low-grade ores, concentrated, and agglomerated into round balls that are thermally hardened or cold-bonded to form pellets. Pellets are then transported to blast furnaces or direct reduction operations where they are used to produce iron; iron is further refined and shaped into the wide variety of steel-based industrial and consumer products in use today.Over the years, pellet production has become increasingly more prevalent with the increased exploitation of low-grade iron ores and increased iron and steel consumption around the world. In 2010, world iron ore pellet production was 388 Mt. It could be argued that the current pellet production process has been enabled by the use of binders – practical experience has shown that it would be nearly impossible to agglomerate iron ore concentrates using rotary drums and discs without using a binder."

Jan 1, 2015

By G Luxbacher

Computer simulation of mine ventilation systems is rapidly becoming an essential tool in mine planning and design. This paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve mainly for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria, could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1977

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

There are several methods (empirical, statistical, and machine learning tools) to calculate blast-induced ground vibration. Still, due to complications in the blasting procedure, under varying blasting loads and strata conditions, it is not easy to predict and simulate blast vibration precisely. Therefore, a study was conducted to simulate the field blast data in Ansys software using explicit dynamics. For this study, monitoring of ground vibration for 20 single hole blasts was carried out. The density of emulsion explosives was in the range of 0.9 to 1.15 g/cc. In the laboratory, rock properties were determined from the rock sample collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and the density of the emulsion explosive were also determined. These parameters were used for numerical analysis to know the ground vibrations at specified points. The results of ground vibration predicted by the model are validated using field data.

A virtual reality approach is presented that can aid entities such as mining companies and land use planners in communicating a visual understanding of a mining operation to interested stakeholders, citizens? groups, and public committees. These visualizations are particularly useful in permitting, production planning and mining closures, contributing to accurate communication and evaluation of mine plans, ultimate land use and evaluation of potential design options A case study is presented, that was created using commercially available virtual reality tools, to emphasize the benefits of visualization technologies in the sustainable development of mineral resources.

Jan 1, 2003

By Kurt M. Larson

Future haulage cost projections led Foster Yeoman Limited into developing a fully mobile crushing and conveying system at its Torr Works quarry in Somerset, England. The purpose-built system has an effective throughput of 2,500 tonnes/hour and features an Orenstein and Koppel (O & K) manufactured walking frame, a Fuller-Traylor type 54 X 74 TC gyratory crusher, and unique mobile conveyor modules designed and manufactured by Foster Yeoman. Used in a single-bench operation in this 6 million-tonne per annum limestone aggregate quarry, the system is fed at the production face by 2 Caterpillar 992C loading shovels. The entire system is moved on a daily basis following production face locations.

Jan 1, 1986

By H. Yen, D. E. Walsh, H. K. Lin

"Comminution circuits are widely used in nonferrous and precious metals milling. Steel crushers, grinding mills and grinding media are typically used in comminution circuits. Comminution circuit wear products, in the form of metallic iron (steel) fines, are unavoidably produced and report to undersize products in the classification circuit, i.e., flotation or leach feed, while tramp grinding steel (TGS) reports to classification oversize products and returns to the grinding mill, building up in the circulating load. In laboratory studies, TGS reduced grinding efficiency significantly, the impact being dependent upon the size of the TGS present in the mill. Because iron fines adsorb flotation reagents effectively, iron fines increase reagent consumption and reduce flotation recovery. Iron fines are also capable of reducing gold recovery in cyanidation circuits via a cementation reaction. When using filtered gold solution from the cyanidation circuit of an Alaskan gold mine, the gold concentration in solution was reduced by 0.2 to 2.6% over various reaction periods when iron fines were present in the solution.IntroductionComminution circuits are widely used in copper, lead, zinc, nickel, cobalt, molybdenum and precious metal mills. Flotation and leaching processes are usually preceded by comminution (crushing and grinding) circuits in order to liberate valuable minerals for effective separation, concentration or dissolution by the subsequent flotation or leaching processes.Steel crushers, grinding mills and grinding media are typically used in comminution circuits. Comminution circuit wear products, in the form of metallic iron (steel) powder, are unavoidably produced and report to undersize products in the classification circuit (flotation or leach feed), while tramp grinding steel (TGS) reports to oversize productions during classification and returns to the grinding mill, building up in the circulating load. Variables affecting the amount of metallic iron powder and TGS produced in a comminution circuit include ore hardness, grinding mill operating conditions, comminution circuit design and the metallurgy of the steel used for manufacturing crusher liners, mill liners and grinding media. As one example, a comminution circuit product of 80% passing 200 mesh at the Pogo Mine, AK is estimated to contain approximately 2 kg/t of metallic iron. A finer grind will generally produce a comminution circuit product with higher metallic iron fines content."

Jan 1, 2015

By Emily Wortman-Wunder

As the 2013 president of the Society for Mining, Metallurgy and Exploration, Inc., I am pleased to present the 2013 issue of the Transactions of the Society for Mining, Metallurgy and Exploration, Vol. 334. The timely publication of professional papers that promote the advancement of scientific and technical knowledge is critical for enabling technology transfer. SME plays a key role in this process through its publications. Communication within the mining community is the key to a successful profession and 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 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 2013 Transactions contains 73 papers covering most every aspect of the mining life cycle and encompassing the diverse sectors of our industry including coal, industrial minerals, metals, health and safety and computational methods. It includes all 18 papers published in 2013 in the Technical Papers Section of Mining Engineering magazine (Vol. 65) and all 33 papers published in 2013 in Minerals & Metallurgical Processing (Vol. 30). Additionally, this volume contains 22 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. Some of the many research highlights from 2013 include discussions of perennial issues, such as how to adequately prepare the next generation of mining engineering students for the workforce (Frimpong et al., pp. 44-52) and how to predict and prevent coal mine bursts and bumps (Pariseau, pp. 60-68), the highly anticipated February Rare Earths issue of Minerals & Metallurgical Processing, and papers analyzing electrical injuries in the U.S. Mining industry (Homce and Cawley, p. 367-375) the latest in assessing the safety and efficiency of operations. All 73 technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our publications staff. As the 2013 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, 2013

By Edward Holloway

The basis for the selection of the ultimate pit for an open-pit mining operation is generally opaque. Some form of value-based analysis will generally guide the final decision; however, the value will often gradually plateau while the ultimate pit size continues to increase. There is no established framework to guide specialists in the selection of the ultimate pit, with such decisions regularly made on a somewhat arbitrary basis. The key component that is missing from the analyses typically used to select the size of the ultimate pit is risk. Once risk is quantified within the analysis framework, the decision-mak-ing range is significantly reduced and the process for select-ing the ultimate pit becomes more consistent, replicable and defensible. The technique outlined in this paper provides an approach to including risk in the process used to select the ultimate pit.

Jun 1, 2024

By Yuting Xue, Brijes Mishra

The relaxation test on sandstone specimens showed typical behavior in pre-failure region and stepwise behavior in the postfailure region. Overall, more significant stress relaxation occurred within the failed specimens than the intact ones. Numerical simulations were conducted with pre-defined failure plane and with Voronoi tessellation to visualize the relaxation behavior. The model with pre-defined failure plane showed the key role of failure plane and asperity in simulating the step-wise post-failure relaxation behavior. The inhomogeneous stress distribution within failed specimen and the viscous deformation of intact rocks induced high stress concentration at the asperities. The observed step-wise relaxation initiated from the failure of asperity. Furthermore, the simulations with Voronoi tessellation showed time-dependent fracture development during relaxation in post-failure region. The presence of fractures completely changed the stress distribution. Stress concentration occurred at the front area of fractures and at the interacting areas between fractures. During relaxation, fractures still developed with time and the sudden significant increase in the “damage” coincided with the acceleration of stress relaxation leading to step-wise relaxation. Finally, the results showed the possibility of using residual strength as the long-term strength of failed rock.

Jun 25, 2020

By Brian Fulcher, Matthew Bartlett, Jarrett E. Carlson

This paper discusses the challenges to complete the construction of two large underground Metro stations and connecting tunnels in the Tren Urbano system. The completion work includes the installation of specialized mechanical and electrical systems, extensive architectural finishing as well as coordination with systemwide power and controls installed by others. A unique feature of this project was the simultaneous design and construction of the structural/civil/architectural/mechanical/electrical works by KKZ separately from the power and control systems under the management of the Owner, its consultants and other contractors. Completion of this project comes after almost six years of continuous design and construction in a dense urban environment. The project was confronted by many challenges that could only be met with the combined efforts of the Joint Venture team in close cooperation with the Owner and its System wide Contractor. This paper will also address many of the major design and construction changes implemented to suit the Owner’s requirements.

Jan 1, 2003

By A. Navarra, F. Mucciardi, H. Marambio, R. Parra, F. Oyarzún

"Discrete event simulation (DES) is an appropriate framework for the plant-wide analysis of copper smelters. These smelters apply a common set of chemical reactions: copper-iron sulfides are blasted with oxygen-enriched air, sending the iron into a slag phase and the sulfur into the offgas. Moreover, conventional copper smelters exhibit similar operational dynamics: a smelting furnace operates continually, feeding into an alternating set of converters that produce batches of blister copper. The thermochemical and operational commonalities of copper smelters are integrated within the DES framework. This serves as a common basis to begin evaluating the system dynamics of individual smelters. For complex problems, the simulation framework should be developed in phases, incorporating feedback from different personnel who have complementary perspectives. Sample computations are provided in this paper based on the Hernán Videla Lira smelter, whose production is constrained by meteorological conditions. IntroductionWorld copper production is approximately 18.5 million t/y (Brininstool, 2015), worth $80 billion a year. Out of this total, 75 percent comes from the pyrometallurgical processing of sulfide minerals (Fig. 1), which occurs in copper smelters. The remaining 25 percent is from the hydrometallurgical treatment of oxides and complex ores (Rotuska and Chmielewski, 2008), which uses solvent extraction and electrowinning.The current paper describes the pyrometallurgical processing, recognizing that the underlying thermodynamics and kinetics are well known (Degterov and Pelton, 1999), with the notable exception of minor element transport, such as arsenic (As), antimony (Sb), bismuth (Bi), silver (Ag), gold (Au). The latter is an ongoing area of research, as smelters are faced with increasingly complex ores (Devia, Wilkomirsky and Parra, 2012; Swinbourne and Kho, 2012). This paper focuses on the system dynamics of copper smelter operations, which has received considerably less attention than the chemical thermodynamics and kinetics.Smelter engineers and managers may contribute to the sustainability of their plant by improving their understanding of operational system dynamics. Indeed, we have prompted smelter improvement projects (Navarra, 2016; Navarra et al., 2016; Navarra and Mendoza, 2013) simply by adapting methodologies that are commonly used in other sectors. These previous works incorporate principles from computer-integrated manufacturing (Groover, 2000) and theory of constraints (Dettmer, 2007), featuring the use of discrete event simulation (DES)."

Jan 1, 2017