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By Camilo Quintero, Frank Cesario, John Kinnear, Brian Boye

In this paper, an innovative approach was adopted to automatically calculate the effects of tunnel induced settlement on buildings and utilities. The approach resulted in increased output quality, consistency, reduced time, cost savings and a greater ability to respond quickly to design changes. The techniques described have been applied to the Fairbank Silverthorn Storm Trunk Sewer System project, located within the City of Toronto. The automation allowed a very large area of topography, tunnels (6 km), buildings (9000) and utilities (over 1000) to be rapidly evaluated. Visualization of the settlements and impacts also allowed the project design team to optimize the system design to mitigate the settlement impacts.

Jun 13, 2021

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. An alternative parameter, the organic efficiency, does indirectly consider process economics, but it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach, the partition moment of inertia, is introduced. This parameter reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure that promises better use of performance data. IntroductionPartition curves are commonly used in the characterization, evaluation and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, density separators and other beneficiation technologies that are based on intensive physical properties. Graphically, the partition curve depicts the recovery of particles as a function of the physical property on which the separation is based, such as particle density, size or magnetic susceptibility. Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic S shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout, or bypass, values; the midpoint slope; and the separation cut point, defined as the property value with 50 percent recovery.Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, as a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point, that is, an infinitely large slope. One common formulation of this slope, the Ecart Probable, Ep, is derived by evaluating the slope between the 25 and 75 percent recovery points:"

Jan 1, 2016

By Hamid Maleki

Rock mechanics models are “data-limited,” i.e., one seldom knows enough about a rock mass to use computational models unambiguously. Statistical methods, however, are capable of being applied where there are good data but a limited understanding of certain natural phenomena, such as the creep of rock salt or elevated risk domains associated with violent failure of strata commonly referred to as coal bumps and coal bursts. Important to these evaluations are (1) having statistically valid data collected consistently and (2) incorporation of analytical calculations for quantifying geologic, mining and particularly geotechnical variables. By combining the strength of the statistical and analytical models, an improved “hybrid” model is created and utilized. To demonstrate the use of hybrid statistical-analytical techniques in rock mechanics problems, three case studies are used. The first case study involves a historic examination of a nuclear waste repository in rock salt, where mathematical models are built using excavation con- vergence data to identify significant variables and estimate future deformation and stability. This case study uses the convergence rate at up to 121 locations of different ages and geometries using monitoring data over the facilities' footprint excavated through 1998. The second case study focuses on ongoing analysis of coal burst mechanics and associated factors. Within the last three decades, a hybrid statistical-analytical methodology has been applied for identifying significant factors affecting coal bursts. This final hybrid model utilizes data from 30 case studies from Utah, Colorado, Kentucky, and other Eastern U.S. mines providing predictive capability for the entire United States coal fields. The last case study is the assessment of Castlegate Sandstone escarpment stability using historic data collected over 17,000-ft of sandstone escarpment exposure in the vicinity of longwall operations in Utah. Results from all three case studies are used for demonstrating the utility of the method in solving ground control problems.

Jun 25, 2024

By E. Milosavljevic, C. H. Bucknam, K. L. Gabby, T. C. Eisele

"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. IntroductionThe dissolution of mercury along with precious metals during cyanide leaching is a long-standing problem, which can result in significant mercury toxicity issues (Washburn, 2003). Mercury is first dissolved by the cyanide solution, and then, since it has a great deal of chemical similarity to silver, it follows silver throughout the concentration and recovery processes, ultimately being recovered as a silver/ mercury amalgam when the metal is precipitated by either the Merrill-Crowe process or by electrowinning.While it would be desirable to either prevent mercury dissolution entirely while still allowing silver dissolution, or to selectively capture mercury before the precious-metals recovery step, there is not yet an effective and economically practical approach to doing this (Grosse, 2003; Ravichandran, 2004; Misra, 1998; Pai, 2000). There are a few processes that have been proposed, such as differential adsorption. While activated carbon, as used in the carbon-in-pulp process, is not highly selective between mercury and silver (Washburn, 2003), it may be possible to achieve some separation by selective elution of the carbon to produce high-mercury and low-mercury eluates (Bunney et al., 2010). Certain synthetic resins were shown to be selective for gold but are more expensive than carbon, requiring special equipment, and have not yet been shown to be selective for mercury (Grosse, 2003). There may be potential for differential dissolution approaches, as thiosulfate leaching does not dissolve mercury sulfides as readily as it dissolves gold (Oraby et al., 2010), and it is possible that it may be similarly more selective for dissolving silver relative to mercury. Some work has also been done with selective precipitants, such as sodium polythiocarbonates (Bucknam, 2007), and 1,3-benzenediamidoethanethiol (Matlock, 2002). Common problems with these approaches include introduction of a solid:liquid separation step, reagent costs, the need to measure the mercury concentration for process control for minimizing silver losses, and regulatory requirements to retort otherwise stable mercury concentrates."

Jan 1, 2015

By T. Wohlford

Due to the increases available base of scientific knowledge, increased independent review required by worldwide security exchanges, and the need for accuracy in characterizing mine water resources, it has become necessary to produce a more accurate hydrologic balance. This presentation provides a critical review of the steps and tools to compile a complete hydrologic review of a mine property. The forces of regulation, increased scientific analysis, better tools, and stakeholder expectations have created a perfect storm of accuracy demand. Ausenco has developed protocol to achieve the desired end.

Feb 23, 2014

By Shenghui Chu, Zhibiao Guo, Dongshan Yang, Yuanxin Zhao, Xiaohui Kuai, Jingwei Gao

The technology of automatically formed roadway without pillars (AFRP) via roof cutting and pressure releasing (RCPR) is a reformatory method for gob-side entry retaining, which automatically creates a roadway by utilizing the fragmenting and expanding properties of rock strata and the mining pressure, to realize a novel technique for coal mining without coal pillars. The Anju Coal Mine is the first kilometer-deep mine where this technology is applied. To conduct a geomechanical model experiment, this research uses the 5307 working face in this mine as its backdrop. The experimental results show that this technology can efficiently decrease the pressure of the AFRP surrounding rock. The roof maximum stress of the AFRP is 21% lower than that of the belt roadway, while the side abutment pressure of the former is 13.4% lower than that of the latter. The comparison of model experiment data and field monitoring data shows that the roof and floor approaching deformations on the roof-cutting side and solid coal side of AFRP differ by 8.8% and 9.6%, respectively. The model experiment results and field monitoring data show good agreement, and the deformation of the AFRP surrounding rock can be successfully managed by this technique. The study’s findings can serve as a guide for using this technology in kilometer-deep coal mines.

Jul 31, 2023

By Jacob Grasmick, Bill Newns

Despite ongoing digitization and “hardware” technological advances, geotechnical uncertainty remains the most significant risk in underground and tunnel construction. And, whilst they are commonly held up as an example of the sophistication of the industry, the practice of drafting and using geotechnical baseline reports is subject to a wide range of influences, not all of which support good risk management. Uncertainties in predicting ground behavior, the gap between the pre-construction assumptions, and the systemic response to construction remains a significant technical and communication challenge. Accordingly, this paper presents a framework to quantify geotechnical uncertainty using geostatistics and translate these into practical tools for ground risk management throughout planning, procurement and construction. Adopting even some of the principles of this framework should provide improvements to contract risk management and should assist to minimize the potential for commercial losses.

Dec 1, 2022

By P. A. Lindberg

Early Proterozoic ore deposits in the Verde district at Jerome, Arizona have produced 33.7 million metric tons of ore (1893-1975). The United Verde and United Verde Extension deposits produced most of the ore that yielded 1,644,323,100 kg Cu plus large amounts of Au, Ag, and Zn. These deposits are situated on the fractured and hydrothermally altered apex of a large submarine rhyolitic extrusive (Cleopatra formation). Precambrian lithologies are penetratively deformed and at Jerome the Fl folds plunge steep to the NNW. For the past two decades the volcanogenic model has superseded the replacement theory of ore formation.

Jan 1, 1992

By Jafar Safarian, Leiv Kolbeinsen, Stian Seim, Hossein Salehi

The present work aims to investigate the link between the oxidation and reduction of a weathered ilmenite concentrate in terms of phase transitions, microstructural changes, and element distribution. An ilmenite concentrate sample was pelletized and fired at 1000 °C in air, and as a result, the pellets were oxidized. The oxidized pellets were reduced by hydrogen gas at 1000 °C, which yielded almost complete metallization of the iron content of the pellets. The ore and the pellets were characterized in each step by XRD and SEM techniques, and distribution of elements and phases were investigated. Ilmenite, pseudorutile, and rutile were the main phases detected in the ilmenite concentrate sample, and depending on the weathering degree of the particles, different fractions of the phases were identified in their microstructure. It was found that irregular rutile grains dispersed in a pseudobrookite matrix is the morphology of the oxidized ilmenite phase. However, increasing microcracks and porosities were the only microstructural changes in the pseudorutile phase after oxidation in air. Studying the specific types of the ore particles and their oxidized and reduced forms indicated that the phase distribution in the ilmenite ore particles dictates the phase distribution in the oxidized and reduced ones. Results show that the morphology of the reduced particles includes a titanium (III) oxide matrix in which reduced iron globules are dispersed.

Feb 8, 2021

By S. E. Phillipson

Four massive pillar collapses in limestone mines, and one in a marble mine, occurred between 2011 and 2021 in benched areas at the Appalachian physiographic province. We characterized the rock mass at 43 limestone mines using the Geological Strength Index and, by plotting the results on a physiographic relief map, determined that GSI values between 55 and 70 preferentially occur in the Appalachian and Ouachita Mountains, which were subject to deformation during the Ouachita and Alleghanian Orogenies. Limestone mines located in formations of similar age in the Interior Plains, where deformation was less developed, are characterized by Geological Strength Index values over 80. We present the results of pillar strength calculations that incorporate the Geological Strength Index from mines that experienced massive collapse, as well as from mines with benched areas that did not collapse, to demonstrate the negative effect that a jointed rock mass has on pillar stability. We suggest that pillar designs, particularly those in which benching will be incorporated, should include allowance for rock mass quality. Because of the preferential dominance of lower GSI values in the Appalachians, we further suggest that pillar designs in this environment may require additional engineering assessment, especially where benching is intended. Lower GSI values may often translate into greater overbreak, which results in loss of pillar volume, corresponding wider back spans, and a decreased width-to-height ratio.

Jun 25, 2024

By E. J. Karges

[For reasons well known to Mining Engineers, fine grinding in the wet form is quite universal inn plants engaged in the traction of metallic values from crude ore In the processing, of non-metallic and industrial minerals, however, fine grinding in dry form is the more common method. The crude materials generally contain less moisture than required for wet grinding, and the products are usually marketed or used in the dry form, most of them as powders. To grind wet would therefore entail the addition of water and the expense for drying the product, which is not justified. This paper will concentrate on the particle size reduction or fine grinding of materials to produce a dry powder]

Jan 1, 1963

By Jeremy Cawley, Jeff Murphy, Horry Parker, Brock Gaspar, Jake Keegan

The Lower Olentangy Tunnel project includes 47,000 cubic yards of planned ground improvement for earth pressure balance machine (EPBM) tunneling (5.2 km) and microtunneling (335 m) in glacial soils. Jet grouting started in late 2021 and will continue through 2023 to complete operations at 5 shafts, 14 safe havens, 5 watermain ground improvement zones, and a river crossing. Typical jet grout columns are installed at depths between 15–24 meters. Discrete soil-cement blocks range from 267–8,900 cubic yards in volume. This paper discusses the methodology, testing, and technical considerations associated with jet grouting operations in glacial overburden across an urban environment.

Jun 13, 2023

By S. Upadhyay, A. M. Afrapoli

"Fluctuation in market price of mineral products has enforced mining companies to cut down their operating costs. One useful way of reducing operating costs in mining operations is to make optimal operational decisions, incorporating efficient mining fleet management systems (FMS). Over the last 50 years, several types of FMS have been developed and introduced in the mining systems around the world. However, there are two major shortcomings in existing systems. Firstly, none of the existing systems consider effects of the short-term plan on dynamic truck assignment. Secondly, most of the existing FMSs make decisions in a way that optimize a specific objective while ignoring others. Herein, we propose a multi stage and multi objective FMS that deals with aforementioned shortcomings of the currently available systems. The developed FMS, in its upper stage, links semi-dynamic operational decision making process to the short-term production plan by simultaneously assigning shovels to mining faces and allocating trucks to the shovels by implementing its first multi objective decision making model. Then in its second stage, in a real time dynamic decision making process, it assigns trucks to shovels and corresponding destinations by optimizing its second multi objective decision making model. The developed fleet management system has been verified using an Iron ore case study and the results are presented in this paper. INTRODUCTION Open pit mining method is the most common method to mine mineral from the earth. Based on Wetherelt and van der Wielen (2011) there exist 2500 open pit metal mines that are categorized as industrial scale mines. Over all of those, the amount of material handled using truck and shovel material handling system is more than the amount handled by all other systems together (Humphrey & Wagner, 2011).It has been proven by several studies that more than 50 percent of operating cost in a truck and shovel based open pit mining operation is accounted for material handling (Moradi Afrapoli & Askari-Nasab, 2017, Alarie & Gamache, 2002, Ahangaran et al., 2012). Thus, introducing even 1 to 2 percent cut in its material handling cost saves huge amount of money for the stakeholders. Over the last 50 years, two major areas have been identified to cut this cost. On one hand mining industries have been implementing equipment with higher production capacities, and on the other hand, researchers have been developing operations research techniques to make dynamic decisions as close to optimal as possible to deduct operational costs in truck and shovel based mining operations."

Jan 1, 2018

By William J. Miles

The markets and applications of Wyoming bentonite deposits are primarily determined by the functional properties of a bentonite ore which results from the unique mineralogy and chemistry of each deposit. Commercial bentonite products contain sodium montmorillonite as the major mineral component, with minor concentrations of accessory minerals such as quartz, opal (silica hydrate), mica, feldspar, gypsum and zeolites. The chemical composition of the sodium montmorillonite influences the functional properties of the bentonite in significant ways. The type and concentration of various accessory minerals also influence the acceptability of the bentonite in each market.

Jan 1, 1995

By Xiaochao Shu, Kun Wang, Fanwei Meng, Rui Tao

Rapidly searching for carbonatite-related rare earth element (REE) mineralized systems is of paramount importance to explorers, because these systems provide the world’s most significant supply of REE. Biotite and barite are suitable indicator minerals that can offer reliable elemental geochemical information used for REE exploration. In this study, we provided an elemental geochemical dataset of biotite and barite from Cenozoic REE deposits in the eastern Tibetan Plateau, and compared the obtained data to those of biotite and barite forming in other geological settings. The F (i.e., fluorine) contents in carbonatite-hosted biotites are highly variable, with biotites from mineralized carbonatite complexes having much higher values (1.05–2.37 apfu, where apfu = atoms per formula unit) than their counterparts from barren carbonatite complexes (≤ 1 apfu). It is therefore believed that the presence of high-F biotites can be regarded as a sign for predicting REE reservoirs. Barites in REE mineralized systems contain much higher (even one or to orders of magnitude) total REE contents (ΣREE >100 μg/g) relative to those species forming in carbonate-hosted fluorite-barite deposits and open marine environments. This means that the high ΣREE concentration of barite can serve as an effective index for REE exploration. The above information is integrated into a REE exploration program in which the areas with strong local tectonism along cratonic edges are priority exploration targets, and high-F biotites and REE-rich barites can serve as direct indices for rapidly identifying carbonatiterelated REE mineralized systems at a strategic distance from other geological settings.

Jun 9, 2023

By H. Sevim

Three transportation systems in surface coal mines: 1-Truck Haulage, 2-Belt Conveying, and 3-Coarse-Coal Slurry Transportation are compared from the operations and cost point of Views. Computerized design and cost models were developed and cost data banks were compiled for each system. These models can be used to evaluate transportation systems and layouts that are practiced in most of the U.S. surface coal mines. A typical midwestern area strip mine was considered for illustration purposes. Sensitivity analysis on critical parameters such as production rate, transportation, distance, etc. was conducted and the outcomes are presented.

Jan 1, 1990

By Ahmet Unal

Use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments will be reviewed, giving specifications of some past and currently available systems. The advantages and disadvantages of using various frequencies, system configurations, and specific components, including their construction standards and capability, will be discussed. The remaining challenges to more widespread use of RFID systems for personnel and vehicle tracking will be identified, and recommendations concerning operating environment capabilities will be detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency will be discussed.

Jan 1, 1997

By Ping Li, Baokun Zhou, Lei Yang, Changfeng Li, Erhui Zhang

A uniaxial compression experiment was conducted on standard sandstone specimens to explore the sandstone’s mutation characteristics and early warning interval during deformation and failure. Meanwhile, acoustic emission (AE) and digital image correlation (DIC) techniques were introduced to realize multi-field analysis and cross-validation from the stress field, deformation field, and elastic wave field. The mutation characteristics of rock failure were investigated based on the cusp catastrophe theory. The results showed four mutation points in the destabilization process of sandstone: compressional density, yielding, destruction, and residual retention. As an internal activity characteristic of the sandstone failure process, AE directly reflected the dynamic failure process of sandstone. The stress variation was closely related to the evolution of AE characteristics. Sandstone loading failure was a process of the mutations of releasable elastic strain energy, dissipative energy, and releasable elastic strain energy. The mutation of dissipative energy was used as the starting mark of the sandstone warning state, and the second mutation of releasable elastic strain energy was used as the end mark of the sandstone warning state. Besides, the warning range corresponded to the loading time of 178 to 208 s. Finally, the sandstone instability warning interval was re-determined from deformation field evolution characteristics in the sandstone damage process, with a loading time of 180–204 s. This was consistent with the warning interval specified using the cusp catastrophe theory. The combination of AE, DIC, and cusp catastrophe theory revealed the mutation characteristics and early warning interval of sandstone failure. Hence, the results provide significant importance to predicting rock failure.

Aug 23, 2023

By Edgar Urbaez

Production scheduling is one of the most important factors affecting mine planning. A program -Mine Scheduler -that aids mining engineers with the setup of an optimum open pit production scheduling algorithm has been developed. A mathematical model for open pit scheduling that optimizes the Net Present Value of the cash flows was formulated. A simulated data is formulated as a Mixed Integer Linear Programming (MILP) problem. What's Best by Lindo Systems is used as the MILP solver in Microsoft Excel. The implementation of the algorithm focuses on problem setup, allowing users to easily evaluate, simplify, and develop the model that best fits their production scheduling.

Jan 1, 1999

By Karoly (Charles) Kocsis, Jeff Johnson, Felipe Calizaya, Tulio Dias, Natanna Nunes

Two pressure balancing chambers were constructed at a Colorado coal mine to reduce the risk of spontaneous combustion. Each chamber was established by installing a Kennedy stopping at about 10 ft (3 m) in front of an isolation seal, and equipped with two safety doors, a nitrogen injection system, and a set of environmental monitors. Several pressure balancing tests for different ventilation conditions were conducted in these chambers. During each test, pressurized nitrogen was injected into the chamber and the pressure differentials across the stoppings and seals monitored. This study presents a summary of the results achieved, lessons learned, and the basic requirements to operate a pressure chamber effectively.

Feb 1, 2024