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By George Dials

Good morning gentlemen. My name is George Dials, and I am [vice] president of the Mining and Reclamation Council of America (MARC). The Council is composed of various companies, individuals, and affiliated state and regional trade organizations representing nearly 3,000 companies directly and indirectly involved with surface coal mining in the United States. I am very glad to be here today to address the Society of Mining Engineers of AIMS. While I do not pretend to be an expert in either geological or geotechnical engineering, I am infinitely familiar with the provisions of the Surface Mining Control and Reclamation Act of 1977 (P.L. 95-87) and the Federal regulations that have been promulgated pursuant to that Act. The Office of Surface Mining Reclamation and Enforcement (OSM) was created by P.L. 95-87 within the responsibility for implementing the provisions of the Act and "to ensure that society and the environment are protected from the adverse effects of surface and sub-surface coal mining operations."

Jan 1, 1979

By VASU GANGRADE

Large-opening underground stone mines pose significant ground control challenges, including the risk of massive pillar collapses. These collapses can result in dangerous air blasts characterized by tremendous force and high velocity. Estimating the velocity of these air blasts proves challenging due to the absence of accurate air velocity instruments near the mine portals. To address this issue, this paper proposes a novel approach that leverages closed-circuit television camera footage from the mine. Specifically, it employs the optical flow algorithm implemented in Python to estimate the velocity of the air blasts, providing a valuable tool for assessing and mitigating risks in such mining environments.

Feb 1, 2024

By N. Djordjevic

Introduction The vibration energy that travels beyond the zone of rock breakage is wasted - all it does is cause damage and annoyance. Under favorable geologic conditions, this energy may travel many kilometers before it finally drops bellow the background noise level. This has forced the introduction of more restrictive limits to the allowable vibration levels. To maintain the profitability of a mine or quarry and to comply with environmental protection legislation, blasting needs to be performed in a more predictable way that will ensure that the final results are optimal in both mining and environmental terms. Minimization of ground and induced structural vibration is, therefore, a matter of good blasting practice -not just an attempt to avoid complaints from neighbors. A new approach to blast vibration minimization is presented. The method utilizes the existence of the local minimums in the frequency spectrum of single-hole blast vibration. The results are presented as a delay map showing maximum ground or structural vibration velocity for many combinations of interhole and interrow delays. A blast engineer can use this map to select an optimal combination of delays that will produce a low vibration velocity at a selected location and, at the same time, will be acceptable from the point of view fragmentation or muck pile shape. Response of structures A typical single-story building has two distinctive forms of vibration. The first form is a translatory vibration of the building superstructure (frame), and the second form is a flexural-bending vibration of the structural elements such as walls and floors (Siskind et al., 1980). Walls and floors will have several modes of oscillation. The most important is the fundamental mode of the vibration, as this mode will have the lowest frequency, the largest amplitude and will cause the largest deformations. The vibration of walls and floors is also a source of secondary vibration within a building, due to the movement of loose objects, e.g., furniture and wall fittings (Dowding, 1985). The subjective estimate of the amplitude of a vibration by the occupants of a house will be unrealistically high due to the effect of the secondary vibrations. It is now well recognized that human perception of ground vibration begins at levels that are far below those that will produce minor damage to the most fragile structures. In mining and quarrying operations, complaints regarding vibration levels tend to be determined more by human perception or annoyance rather than by observations of damage. Ground vibrations on the order of 0.08 mm/s (0.0032 ips) (Walter and Walter, 1979; Murray, 1987) can be felt, and they are often subjectively estimated to be about 100 times greater. Amplification of ground vibration in the structure depends on the amount of energy in the ground vibration spectrum that is in the vicinity of the structure's resonant frequencies together with the damping ratio of the structure at these particular frequencies. One way to avoid significant vibration amplification in a structure is to shift the dominant part of the ground vibration away from the resonant frequency range of the structure. The presented method allows for the selection of the optimum blast timing (interhole and interrow delay times) to minimize the resultant ground vibration amplitudes in a given frequency range. It also allows the selection of suboptimal, but still acceptable, blast delay times, which may be preferable from the point of view of overall blast performance. Determining frequency ranges of importance in structures In attempting to avoid amplification of vibrations in the structure, ground vibration amplitude of frequencies close to the resonant frequencies of the building needs to be minimized. The width of the frequency-minimization region is determined by the value of damping in the building. If the damping ratio is low, then the frequency-minimization region around the resonant frequency will be relatively broad. By shifting the dominant part of the ground-vibration energy into the frequency region much higher than the resonant frequency of the building (1.5 to 2 times), it is possible to achieve efficient vibration isolation of the building. In such cases, the structural dynamic amplification of ground vibration will be less than unity. The first step in this minimization process is the determination of the structural resonant frequency. From the frequency spectrum, it is possible to determine the resonant frequency of the structure. Sometimes the

Jan 1, 1998

By D. A. Elgillani, N. A. Abdel-Khalek

The role of ZnS04 in activation of sphalerite (ZnS) and deactivation of lead-activated sphalerite has been investigated. Adsorption of metallic ions at the solid-solution interface, electro kinetic results for sphalerite under different chemical conditions, and thermodynamic calculations were used to elucidate the mechanisms involved. It is shown that flotation response of sphalerite in absence of activators is rather weak and that adsorption of ethyl xanthate on the mineral mainly electrostatic in nature. Zinc sulfate is found to activate the mineral but only in a narrow acidic pH range. This is attributed to the increase of zeta potential as well as the possible increase in amount of negatively charged bulk precipitated zinc xanthate. Lead ions activate sphalerite in a wide pH range and the lead activated mineral assumes a flotation behavior similar to that of galena (PbS). However, addition of ZnS04 depresses the lead-activated sphalerite by replacing lead ions at the mineral/solution interface.

Jan 1, 1999

By Phoebe L. Hauff, Jeffrey P. Kurtz, Paul D. Chamberlin

Clay minerals can be a source of problems in heap leaching operations. The ore for many heap leach operations is commonly acid-sulfate alteration zone rocks which may be found in hot springs deposits as well as the supergene zone of other near- surface gold deposits. Clays can be important constituents of these ores. Swelling clays, such as smectite, can come loose from the agglomerated ore, migrate within the heap, concentrate in pore spaces and often plug up flow channels in the heap Cement is often added to the ore as a binder during the agglomeration process. Lime is added for pH control. Their presence, combined with the sodium cyanide commonly used to leach, can raise the pH of the leach solution to 10 or even 12. This very alkaline solution can cause dissolution of some mineral Some clays, such as kaolinite, are not very stable in high pH solutions. They can be dissolved and reprecipitated as other clay species if sufficient silica and the appropriate cations are available in solution. Silica gels and amorphous materials can also be created from the dissolved kaolinite and other minerals and act as retardants to the flow of leach solutions in the heap. Therefore, before a heap leach operation is built, the operator should evaluate the clays in the ore and test the agglomeration procedure. It is important to know not only the mineralogy and the chemistry of the leach environment but how the minerals and solutions interact and what the products of this interaction are. A hypothesis is presented in this paper that expanding smectite- bearing clays can be generated within the heap. How and why this happens will be explained.

Jan 1, 1987

By Bahne C. Cornilsen, X. Shan, David H. Carlson, John H. Johnson

The air in three U.S. underground coal mines has been sampled. The data developed show the relative importance of the various pollutants and quantify the need for control. Total respirable particulate matter (TRPM) was found to be the critical pollutant (the one requiring the most dilution for control). TRPM is considered to be "respirable coal dust" by procedures approved for sampling in U.S. underground coal mines. However, this "respirable coal dust" also includes diesel particulate matter (DPM) and particulate from other sources. While "respirable coal dust" was the critical pollutant, Raman spectroscopic analysis showed that more than half of this "respirable coal dust" was DPM. The DPM in the samples ranged from 22 to 152% of the 2 mg/m3 limit for respirable coal dust. Thus DPM was the critical pollutant using the 2 mg/m3 respirable coal dust limit. SO2 gas produced by the combustion of diesel fuel containing sulfur was the second-most critical pollutant. Characteristic curve slope (CCS) values were calculated to determine the quantitites of the various pollutants generated per unit of diesel haulage activity. Mine 1 had the highest TRPM CCS values with 29 mg/m3/%C02 for the Ramcar and 57 mg/m3/%C02 for the Haulageway location. The highest coal particulate CCS measured was 30 mg/m3/%CO2 and the highest diesel particulate CCS measured was 27 mg/m3/ %C02. Both of these high values were measured in the Mine 1 haulageway location. Calculations were made to determine the controlling CO2 concentrations (CCC) at which all other measured pollutants would be within their limits. These CCC values, which, for the mines sampled, were based on TRPM, varied from a low of about 0.07% for the Mine 1 haulageway location, to a high of about 0.15% for the Mine 2 Ramcar and haulageway locations. Weekly average CO2 concentrations measured in these mines ranged from 0.09 to 0.11 % for the Ramcar, from 0.05 to 0.09% for the haulageway, and from 0.08 to 0.11 % for the return. The concentrations of TRPM ranged from 1 and 2 mg/m3 in mine areas frequented by personnel, and to greater than 4 mg/m3 in returns where personnel are not exposed.

Jan 1, 1991

By J. G. Groppo, S. M. Khandrika, B. K. Parekh

It is shown that dewatering of fine coal particles (D50 = 21 µm) is enhanced near the point-of-zero-charge. The coal surface is modified by the addition of copper ions and by adjusting the pH to precipitate surface-active metal hydroxy species, which promote agglomeration and produce low-moisture cakes. Filtration kinetics data are used in calculating filter cake parameters from an integrated form of Darcy's law. The influence of copper ions and pH on filter cake parameters and the correlations among them are presented.

Jan 1, 1995

By V. Claremboux

The transformation of raw iron ore into high quality steel can take place via several processes. A general consistent theme involves the upgrading of the iron ores via methods such as flotation and magnetic separation, the preparation of an agglomerate such as via pelletization or sintering, the smelting of the agglomerate into a high grade iron product, and the further refining of iron into specific steel alloys. Each of these steps admit potential for optimizations and alternatives, and the process overall is critical to meeting the world’s continuing iron demands.

Feb 1, 2025

By C. R. McClung

"Molybdenum, in the form of molybdenite, is a common byproduct of many copper mining and concentrating operations. While the recovery of most copper sulfide minerals is principally liberation controlled, the recovery of molybdenite is much more complex, with fully liberated particles commonly lost to tailings.A geometallurgical investigation was undertaken of molybdenite from the Bingham Canyon deposit with the aim of determining what effects, if any, mineralogy and the mineralogical attributes of morphology, angularity, liberation and size have on molybdenite recovery in the processing circuit. A set of samples was collected from the ores and products of Rio Tinto Kennecott’s Copperton Concentrator. The samples were analyzed by normal polarized reflected light microscopy, X-ray diffractometry, and scanning electron microscopy using a Mineral Liberation Analyzer, revealing the presence of two distinct types of molybdenite, which are the two polytypes: hexagonal (2H) and rhombohedral (3R). The 2H polytype occurs as textbook-shaped particles in quartz-molybdenite veins located in the core of the deposit, while the 3R polytype occurs as disseminated, ball-shaped particles with a dull or frosted appearance along the margins of the mineralized intrusive body or central core. Each polytype exhibited metallurgical properties consistent with those reported in the literature. The 2H polytype is easily ground, kinetically “faster” floating and displays surface attributes that are amenable to higher rates of recovery. This commonly results in the production of a high-quality molybdenum concentrate under normal operating conditions at most copper concentration operations. The 3R polytype is difficult to grind, kinetically “slower” floating and displays surface attributes that are less amenable to recovery. Therefore, in deposits with higher concentrations of the 3R polytype, modifications to operating parameters may be necessary to improve the recovery of molybdenite.A preliminary investigation into the metal budget of porphyry copper and molybdenum deposits indicated a possible positive correlation between total economic metal budget and polytype content. Higher concentrations of the 3R polytype appear to be more prevalent in gold-enriched porphyries than in molybdenum-enriched porphyries. This may help explain why it is easier to obtain higher rates of recovery in molybdenum ± tungsten-rich deposits, which contain little to none of the 3R polytype. There is a potential for the metal budget of a porphyry deposit to be used as an indication of the molybdenite polytype present as well as its impact on the economics, in terms of exploration, and the processing circuit, in terms of plant design."

Jan 1, 2016

By Dion Weatherley, Raúl Castro, RENE GOMEZ, Pablo Cid

The study examines the impact of different drawbell geometries on hang-ups during ore extraction in underground mining. Using the discrete element method, the research compares three drawbell geometries: drawer, circular, and El Teniente. The findings indicate that the El Teniente geometry experienced more hang-up events, while the circular geometry had fewer.

Sep 1, 2023

By Rusty Winn

"R.E. Janes Gravel Co. is an aggregates producer is located along a paleo-channel of the Ogallala formation (locally known as the Slaton Channel) approximately 48.3 km (30 miles) southeast of Lubbock, TX. In an attempt to beneficiate the 25.4-mm (1-in.) concrete aggregate product, a log washer was installed in the processing line to liberate and remove fines (clay) from the finished product. The introduction of this extra cleaning step increased fines in the finished product, exacerbating the original problem. Several other processing options were investigated before a geological analysis was undertaken to try and define the lithology of the formation and formation characteristics in an attempt to alleviate this problem.Initial assessmentsThe mined resources are mid-Miocene to early Pliocene (16-4 mya) in age and is the eastern exposure of the Ogallala formation of the Southern High Plains escarpment. The Ogallala formation consists of coarse-grained alluvial sediments in paleovalley channel ways from the Rocky Mountains with fine Aeolian and paleosol deposition on the uplands across the High Plains region of the United States. Locally, these Rocky Mountain sediments from New Mexico were transported and deposited in a paleochannel that is approximately 0.805 km (0.5 miles) wide and 15.25 to 18.3 m (50 to 60 ft) in depth. As this channel cut across the Southern High Plains it eroded local rock sources of Late Cretaceous limestones and Triassic sandstones and mudstones incorporating them into the younger Ogallala depositional sequence.Depositional historyThe channel currently being mined is a nontypical Ogallala deposit. The Ogallala in the panhandle of Texas is divided into two units, the Couch and the Bridwell. The Couch is the older of the two and exhibits alluvial sedimentation of thicker and larger gravel (up to 76.2 mm or 3 in.) deposits fining upward to Aeolian sedimentation and thick friable caliche deposits. The Bridwell overlies the Couch and is characterized by alluvial sedimentation, a distinctive red tint and smaller gravel components (typically no larger than 25.4 mm or 1 in.) fining upward to Aeolian sedimentation and thick, well-indurated caliche cap. The Slaton Channel divides these two units and shares lithologic components of both, yet is lithologically distinct due to its Cretaceous Age limestone gravels that can be < 3.66 m (12 ft) in size. Caliche/calcrete is a calcareous (CaCO3) deposit that forms in the B horizon of soils as a rain water leachate of CaCO3 from the upper A horizon."

Jan 1, 2014

By Frank W. Pereira

The Montana Talc ore body was discovered in 1983 in Montana&apos;s Gravelly Range, about 40 km (25 miles) south of Ennis. Initial drilling indicated a 910-kt (1-million st) ore body of high purity talc. Preliminary analyses on ore cuttings included chemical analysis, brightness measurements, and microscopic evaluations of the structure of the talc. Results indicated it was similar to talc currently being marketed from Montana and it would probably have good commercial value. Based on the positive test results, a test pit was made and a 180-t (200-st) sample of ore was mined. A portion of the ore was ground to various particle sizes and evaluated to determine its strengths, weaknesses, and other characteristics. The deposit is located close to the Cyprus Yellowstone deposit. It was therefore believed that Montana Talc ore may possess many of the same characteristics. Testing and analyses showed the talc to have a high purity and an extremely large surface area, even for Montanatype tales. The ore was also situated in a massive deposit, indicating low cost mining. While the lab analyses were encouraging, the true evidence would be obtained from commercial tests in the marketplace. About 91 t (100 st) of ore were ground to product specifications for pitch control, paint filler, and plastics filler. Consumers were contacted and requested to evaluate the sample talc products. A major trial for the talc as a pitch control agent was arranged at a Northeast paper mill. The trial indicated the new Montana Talc product performed as well or better than the current standard in the industry. In fact, due to a minor modification in the compaction process to make the transport of the talc easier, the product had substantially less dust than the currently used product. The operating people at the paper mill requested that management purchase this talc. Trials were also run at paint plants for use as a pigment filler. And the talc was fabricated into a number of plastics compounds. The initial product tests were largely positive and provided encouragement to proceed with the project. Different grinding mills were used and their performance evaluated. Significant data were generated by the custom grinders. They indicated how the Montana Talc ore ground and the particle size distributions produced at different grinding settings. Encouraged by the positive marketing tests, a prefeasibility study was commissioned. A talc grinding plant and mine plans were designed and capital and operating costs estimated. Initial economics showed an attractive return. The operating costs were among the lowest in the industry. The positive economics, along with the excellent results by the products in the marketing tests to the paper, paint, and plastics industries, led to the recommendation to proceed with the project. Plant construction began in June of 1985. The Montana Talc Co. (MTC) analyzed the data from the commercial tests. Based on the product&apos;s outstanding performance and the uniqueness of its high purity and platy structure, a strategy was developed to position the company as a premium talc supplier.

Jan 1, 1989

By Peter Bryant

"The case for innovation in the mining industry has never been more compelling—whether you believe the industry is in a sharp dip in a significant ‘sawtooth’ cycle or in the midst of a bust — the imperative is the same. Despite record production levels and still above-average prices compared to the lows of 2000, the industry is struggling to make profits and provide the returns on capital that investors are seeking. This represents a large-scale destruction of value over the last 15 years.The last 10 years have seen a sustained rise of operation expenses and capital development costs while there has been a rapid decline in productivity. This trend is unsustainable especially against other key structural challenges and forces shaping the future of the industry:1. Despite short-term fluctuations, there is longterm sustained demand for commodities.• Demand is driven by relentless urbanization, population growth and a rapidly growing middle class.2. Environmental concerns continue to mount.• Existing mining methods and their environmental footprint are becoming increasingly unacceptable to society.3. Geopolitical pressures and community activism are growing.• An estimated $25 billion worth of projects are on hold due to community activism.• Increasing nationalism tendencies and government expropriations of close to $30 billion.• Social license to operate is being challenged.4. Finding, building, operating and closing a mine just keeps getting harder and more expensive.• Costs have been increasing at an annual rate of 10 to 15 percent for the last 10 years.• More assets are stranded as they become uneconomical to mine under current mining methods, e.g. Olympic Dam.• Ore grades continue to decline.• Declining productivity at an annual rate of more than 10 percent for the last 10 years.5. The industry has consistently underinvested in technology and innovation."

Jan 1, 2015

By Ping Zhang, Xu Ma

Perturbations from mining operations significantly affect the stability of rock masses, especially with the increase in mining depths. This study uses the discrete element method (DEM) to investigate shear slip failure along discontinuities in an underground mine, aiming to quantify seismic moment and seismic energy to better understand seismic hazards.

May 1, 2023

By Christopher Mark

Sixty years ago, underground coal mining was the most hazardous job in the United States. Roof falls killed about 100 miners every year, more than all other causes put together. Fast forward half a century to 2016, and the first year ever with zero roof fall fatalities. Just three miners were killed by roof falls during the following six years. To understand how this historic goal was achieved, this study analyzed hundreds of roof fall fatality reports covering five decades. It found that the immediate effect of the Federal Coal Mine Health and Safety Act of 1969 (Coal Act) was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof control plans, which the U.S. Bureau of Mines had been advocating since the 1920s, fostered the necessary improvements in both the safety culture and the mining technology.

Jun 1, 2024

By John C. Edwards, F. Friel, John J. Opferman, Robert A. Franks

A series of diesel fuel fire experiments were conducted in the Pittsburgh Research Center&apos;s Safety Research Coal Mine (SRCM) to determine products-of combustion (POC) spread rates along a single entry under zero imposed airflow conditions. Six experiments with an average fire intensity of 330 kW and three experiments with an average fire intensity of 30 kW were con- ducted in a 180 m long entry which had an average 2 m height and 4 m width. POC spread rates were measured by the response time of diffusion type CO detectors, positioned at 30 m intervals, to CO concentrations 5 ppm above ambient. For the 330 kW fires, average POC spread rates of 0.22, 0.1 3, and 0.06 m/s were determined at 30, 60, and 90 m distances from the fire. For the 30 kW fires these average spread rates were reduced to 0.08, 0.04, and 0.04 m/s. The measured maximum roof layer temperature 30 m from two of the 330 kW fire was 30 and 36"C, which is less than the 57°C alarm point of a typical mine thermal sensor. It was determined that smoke detectors can be more effective for mine fire detection than CO detectors. The experimentally determined POC spread rates can be used to provide guidance for specification of sensor spacing to improve early fire detection at zero or very low air flows.

Jan 1, 1997

By Claude M. Moreland

It is common practice when thermally drying coal from wet coal preparation facilities that the coarse +0.5mm fractions and fine fractions (-0.5mm) are combined and fed to a thermal dryer. There are very good reasons for this concept. The coal feed is much easier to handle in this condition for it is not as likely to stick inside the dryer or hang up in the material handling equipment, and is easier to feed and discharge. However, it is generally only the -0.5mm fines that really need to be dried. The +9.5m fraction of the cleaned coal will leave the dewatering screens, or drain and rinse screens, at an acceptable surface moisture, probably 5 or 5 ½ percent. The 9.5m x 0.5mm mesh fraction can be centrifuged to about 8 percent. The -0.5m fines can range from 18 to 22 percent or more, depending upon the type of equipment employed to dewater, and upon the size distribution within this size range.

Jan 1, 1982

By ANDREW HOBERT, Maoming Fan

Low-cost and environmentally friendly green froth flotation modifiers of plant origin, such as guar gum, carboxymethyl cellulose (CMC) and starch, have been used in the flotation of some sulfide and nonsulfide minerals. This paper discusses the fundamentals, current applications and potential new applications of guar gum, CMC and starch in minerals flotation. In this study, improved flotation performance was achieved using some green modifiers in flotation columns.

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"Prospecting and Exploration. Since the Lake Superior ores occur in pockets or distinct bodies and vary much as to character and location, the actual mining of the ores is preceded by much work of an exploratory character. This work includes prospecting and exploration.Prospecting is the term generally applied to the quest for surface indications of ore, or the conditions which would warrant the expectation of finding ore in the vicinity. It includes such &apos;operations as geological examination, dip needle work, shallow test-pitting, and trenching. The ore bodies of the Mesabi Range are non-magnetic, and dip needle prospecting is therefore valueless. On the Cuyuna range, however, magnetic attraction as evidenced by the dip needle has been extensively employed as a guide to the location of ore deposits; in other localities it has found limited application.Drill Exploration. After the presence of an ore deposit is known or suspected, resort is generally had to exploration by means of diamond or churn drills. On the old ranges geological conditions generally make this manner of ascertaining the exact limits of an ore deposit impracticable; so, if two or three adjacent drill holes develop considerable depths of ore, the sinking of a shaft for underground exploration, development and mining is generally considered warranted. On the Mesabi Range, however, the flat-lying and comparatively shallow characteristics of the ore formation warrant much more extensive drill explorations. On this range, then, an ore body &apos;is almost invariably followed· out with the drills, and its limits are determined to the point where the complete plan of development can be worked out in advance of actual mining operations"

Jan 1, 1920

By C. McKinnon

Climate change is the central challenge facing the mining industry, wherein producers must simultaneously ramp up production to provide the raw materials for clean technologies while transitioning to carbon neutrality. While transitioning to renewables will take time, mines can start improving energy efficiency while improving productivity today. This paper proposes a novel technology ecosystem that can help. By monitoring mine shovels, loaders, haul truck paths, and conveyor belts, the proposed technology enables particle size measurements throughout the operation, truck and belt volume monitoring, ground engaging tools monitoring, and boulder detection.

Mar 2, 2022