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By M. K. Larson

"Specialized numerical modeling codes have been developed over the years to estimate ground stresses during the excavation of coal in underground mines. One of these tools, MULSIM, a displacement discontinuity boundary element code, was last developed by Zipf into a version called MULSIM/NL [USBM 1992a, 1992b]. The code was used frequently in years past, but closure of the Bureau of Mines in 1996 marked the beginning of a pause in its development. A similar tool with distinctly different treatment of overburden idealization, LaModel, was subsequently developed [Heasley 1997] and largely displaced MULSIM/NL in the literature. However, recent work modeling deep western longwall coal mines [Larson and Whyatt 2013] has demonstrated that MULSIM has distinct advantages for regions with relatively stiff and strong overburden. This work required that MULSIM be revived and updated into a version called MulsimNL/Large. Updates include larger array sizes, greater precision, greater number of materials, and the addition of a five-point, six-segment pillar load/displacement model that provides the user a more flexible coal-strength model allowing hardening and softening before a final residual strength. MulsimNL/Large has the ability to calibrate to large load transfer distances observed in some western U.S. coal mines that appear to be caused by strong, massive units in the overburden and/or floor of a coal mine. Also, it provides the ability to calibrate gob stiffness to simulate measurements or estimates of overpanel weight distribution between gob and abutment, while still maintaining load transfer distance with minor adjustments. MulsimNL/Large can easily implement material strengths calculated from various pillar strength models. The five-point model gives MulsimNL/Large the ability to easily simulate pillar behavior that is extracted from detailed pillar models, such as FLAC3D. MulsimNL/Large or similar approaches should be considered for evaluating mining layouts where stratigraphic conditions are known to cause overpanel weight to transfer to an extent significantly longer than the empirical method widely used to calculate load transfer distances in the U.S. [Peng and Chiang 1984; Mark 1987; USBM 1990]."

Jan 1, 2015

The roasting process of copper concentrates containing variable quantities of arsenic in a fluidized bed regime was analyzed, considering the technical literature published on the topic in the last quarter century. Although emphasis has been given to the analysis in the fluidized bed regime, other processes have also been considered, under a reducing, neutral or oxidizing atmosphere. The kinetic mechanisms of roasting, as well as the models that have been applied or those likely to be used to explain the kinetics of arsenic removal, are analyzed. Regarding the kinetic mechanisms, those that have been applied to copper concentrates with both high and low arsenic content are included. The roasting kinetic model includes the kinetic data analysis techniques, general models, equations and an estimation of the conversion degree through dynamic, differential and integral methods, as well as particular models for mineralogical components, such as smelter dust and copper concentrates with low and high arsenic content.

May 1, 2012

By Paul A. Rittenhouse

First of all, I want to thank John Dunlap for asking me to this AIME meeting in Denver. I was first introduced to Denver and The Rocky Mountains more than ten years ago and immediately decided it was one of the most attractive spots in the world. I've come back many times since and still welcome any opportunity to return, even if it means I have to prepare and give a paper on potash. When John Dunlap gave me this assignment, he told me that the program would include papers on the geology of potash, papers on new discovered potash deposits and new mines and asked me to discuss potash from the commercial point of view. He also asked me to include a supply/demand outlook for potash. However, one thing he did not mention was "how far into the future he wanted me to look" and it seems to me the time element is a crucial factor to you who are both geologists and miners as well as to me. In your case, you have to look far enough into the future to give you time to explore, find, evaluate, develop, and bring into production a commercial deposit. My mining associates and friends don't agree on how long that takes but it's probably somewhere in the range of eight to fifteen years. But, they all agree on one thing and that is that the time required is continually getting longer. Now my time problem is just the opposite. It is "relatively" easy, and I stress relatively, to identify and evaluate the importance of the various factors that impact on both the supply of and demand for a commodity such as potash if the time period is today. It gets a little tough if one has to project into tomorrow or next week or next month. And when we start talking in terms of a year, five years or ten or fifteen years, things really get sticky and the old crystal ball becomes mighty cloudy. But we economists and forecasters are not known for our temerity so let me get on with the job at hand and take a look at the world potash supply/demand outlook.

Jan 1, 1978

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By S. E. Vanderslice, J. A. Hummer

"The results of laboratory evaluations were used to compare the potential of two alternative, biomass-derived fuels as a control strategy to reduce the exposure of underground miners to aerosols and gases emitted by diesel-powered equipment. The effects of fatty acid methyl ester (FAME) biodiesel and hydrotreated vegetable oil renewable diesel (HVORD) on criteria aerosol and gaseous emissions from an older-technology, naturally aspirated, mechanically controlled engine equipped with a diesel oxidation catalytic converter were compared with those of widely used petroleum-derived, ultralow-sulfur diesels (ULSDs). The emissions were characterized for four selected steady-state conditions. When fueled with FAME biodiesel and HVORD, the engine emitted less aerosols by total particulate mass, total carbon mass, elemental carbon mass and total number than when it was fueled with ULSDs. Compared with ULSDs, FAME biodiesel and HVORD produced aerosols that were characterized by single modal distributions, smaller count median diameters, and lower total and peak concentrations. For the majority of test cases, FAME biodiesel and HVORD favorably affected nitric oxide (NO) and adversely affected nitrogen dioxide (NO2) generation. Therefore, the use of these alternative fuels appears to be a viable tool for the underground mining industry to address the issues related to emissions from diesel engines, and to transition toward more universal solutions provided by advanced engines with integrated exhaust aftertreatment technologies. IntroductionDiesel engines have been the workhorses of modern society for industrial and transportation enterprises. Diesel engines of all generations are extensively used in a variety of light-, medium- and heavy-duty applications in underground mining operations around the world. Fuels obtained from various sources and with wide-ranging chemistries have been combusted in diesel engines. However, the bulk of the currently used fuel can still be traced to nonrenewable petroleum sources. The petroleum-derived diesel fuels are primarily made up of saturated acyclic hydrocarbons (parafins or alkanes), aromatic hydrocarbons (arenes or aryl hydrocarbon), and unsaturated hydrocarbons with double bonds (olefins and alkenes). Improvements in the quality of petroleum-based diesel fuels was identified in federal regulations as an important piece in resolving the puzzle of diesel engine emissions (Environmental Protection Agency, 2001, 2004). The reduction of U.S. diesel fuel sulfur content below 15 ppm had the effect of lowering sulfate emissions and enabling the development and implementation of catalyzed emissions control technology across a wide spectrum of applications."

Jan 12, 2017

By Y. Wang

Wet magnetic separation methods for recovering hematite and chromite fines and ultrafines are investigated in this paper. These methods include wet high intensity and high gradient magnetic separations, carrier or "piggy-back" magnetic method, magnetic field-induced aggregation and magnetic seeding. This investigation indicates that wet magnetic separation is more efficient for fines and ultrafines whereas other methods can be used to enhance the particle aggregation and/or the magnetic response. The magnetic behaviour of these minerals with respect to magnetizing field, particle size and temperature is also presented.

Jan 1, 1993

By Y. Wang, E. Forssberg, R. J. Pugh

The coagulation of dispersed ultrafine weakly-magnetic oxide mineral particles (e.g., natural hematite and chromite) in an external magnetic field can be described by interparticle forces. Essentially, coagulation occurs when the short-range London-van der Waals interactions and the long-range magnetic forces outweigh the stabilizing electrical double-layer repulsion. Using the classical colloid chemistry theory, the various components of the potential energy for different-sized particles at a series of ionic strengths and magnetic field intensities were calculated. The results of this theoretical analysis were then related to the results obtained from experimental studies in which the magnetic field-induced coagulation of the ultrafines of natural hematite and chromite in aqueous suspensions were investigated using a laboratory-scale electromagnetic solenoid. The experimental results relate the coagulation process (as determined by magneto-sedimentation analysis) to the particle size, the slurry pH and the external magnetic field. In the magnetic fields, the maximum coagulation occurred near the pH of zero-point-of-charge (pHzpc) of the minerals (where the electrostatic double layer repulsion was reduced to a minimum) enabling the particles to enter the "primary minimum" energy sink. On the other hand, in cases where the electrostatic repulsion was not suppressed, the long-range magnetic forces enabled coagulation to occur in the "secondary minimum." This caused the formation of chains that appeared to be relatively stable during sedimentation.

Jan 1, 1995

By M. Peters, P. Schmäh

The development of renewable energies and a sustainable power grid are the challenges for future energy supply. Underground cables will replace the vulnerable overhead lines, because of their safety benefits. Due to the public environmental awareness, smart tunnelling and trenchless solutions are required for inner-city and cross-country installations of underground cables, as well as for crossings and the landfall sections to connect offshore wind farms to the transmission grid. Methods from the tunnelling and pipeline industry provide a high flexibility in the planning of alignments, including versatile tunnel concepts and the installation of protective pipes with E-Power Pipe and Direct Pipe.

Jun 13, 2023

By D. R. Tesarik, T. C. Trancynger, W. G. Pariseau

The Davis detector cavern was excavated on the 4850 Level of the former Homestake Mine in the mid- 1960s to house a novel neutrino detector developed by Nobel Prize winner Dr. R. Davis. The original cavern was about 9.1 x 16.8 x 9.7 m high, excavated in a Precambrian amphibolite known as the Yates unit and enlarged in 2010. In 2009, the National Science Foundation selected the site for development as a national Deep Underground Science and Engineering Laboratory (DUSEL). This retrospective rock mechanics study of the Davis cavern is intended to inform design of the much larger caverns and laboratory rooms being considered for the same 4850 Level. Provision for rock mass variability, sequential excavation, jointing and wall damage from blasting are included in analyses that were done using two different computer codes and methods (FLAC3D and UTAH3). The results are in agreement with observations and show that cavern stability is indeed the case. The main conclusions are: (1) if conventional scaling of laboratory rock elastic moduli and strengths is done, then 0.25 and 0.50 scale factors are reasonable, (2) measured statistical and spatial variability in rock properties should be incorporated into geomechanical analyses to better reflect reality, (3) discontinuities (“joints”) are essential to reliable analysis of excavation safety and when properly taken into account eliminate the need for empirical “scaling” of laboratory rock properties, (4) major geologic features such as rhyolite dikes and breccia zones may be important to excavation safety at Homestake and should be explicitly represented in analyses and (5) quantifying wall blast damage is important to engineering design of underground excavations.

Jan 1, 2012

By G. B. McClurg

China was nota factor in the supply of fluorspar to the United States until the early 1980's when it shipped in its first package of Metallurgical lump, that not only was higher grade than the Mexican Metallurgical spar but was also about $30.00 a ton cheaper landed at Burnside. Representatives of the Mexican Fluorspar Institute and several producers made trips to see the Chinese operations supplying their once reserved market place. China, an enigma to most Westerners suddenly became the new contender, with prices that were disgustingly low or so thought the other exporters. Of course China has been mining, producing, consuming and exporting from 400,000 to 500,000 tons per year of various grades of fluorspar but until the first partloads came to the U.S., very little attention was paid to their exports by American-continent producers or consumers.

Jan 1, 1986

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and mediumterm activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter, and ventilation constraints in order to create more realistic schedules and enhance miners’ health and safety.

Sep 6, 2023

By William J. McCutheon

This paper presents some personal observations obtained during the course of visits to Europe, Africa, Latin America and the United States to talk with senior decision-makers in the copper industry about their views of markets, prices and the future of copper. The industry's future has never been particularly easy to define; with the changes of recent years, prediction has become even more difficult. The author's personal assessments of the present and future are offered for comment.

Jan 1, 1986

By David L. Hill

Newmont Gold Company's Mill No. 4 is located along the Carlin trend, about 25 miles North of Carlin, Nevada. The plant consists of a primary grinding circuit using a 7.2 m (22 ft) diameter by 2.6 m (8 ft) long semi-autogenous mill along with a 2.3 m (7 ft) diameter cone crusher. Secondary grinding is performed in a 4.8 m (14.5 ft) diameter by 9.2 m (28 ft) long overflow ball mill in closed circuit with a set of 66 cm (26 in) diameter cyclones. The ground product is fed to a typical carbon-in-leach gold leach circuit. The grinding/crushing circuit operation and control scheme are the topics of this paper.

Jan 1, 1993

By K. E. Robinson

During operation of tailings impoundments, water is lost through decanting, evaporation and seepage. Techniques have been developed to regulate or control each of these components. Collectively implemented, these techniques form the basis of tailings impoundment management. Regulation of the rate and level of decanting influences the size of a free water pond, and, thereby, the amount of evaporation and seepage, which are both area-dependent. Conversely, the encouragement of seepage and/or evaporation could also be used to reduce decanting requirements. Management of one of the components of a tailings impoundment's water balance is reflected in changes in the other components. The seepage component has the greatest potential impact on the environment, and consequently requires the closest scrutiny. Water percolating through tailings backfill transports heavy metals and other dissolved solids from the impoundment into the local groundwater regime. Depending on the seepage volume and concentration of contaminants, seepage from impoundments could exceed environmentally tolerable limits. Once mobilized, seepage-borne pollution is much more difficult to treat, mainly because of the problems in collecting the diffusive transportation medium. Pollution abatement measures relative to tailings impoundment seepage depend on seepage prevention or reduction. Seepage control measures include constructing barriers to flow, pump-back systems of interception and restricting the supply of water available for seepage.

Jan 1, 1987

By T. P. Meloy

Traditionally the mineral and mining engineers have characterized particles by sieving and-settling. Within the last decade, with the advent of the scanning microscope, entirely new experimental and theoretical approachesl-10/have been taken to minutely define the particle surface. This approach depends upon a hypothesis which takes advantage of the recent developments in automatic micro-scopes which can acquire large amounts of information in a short time and the new computational techniques which rapidly reduce the information to meaningful, practical data. Historically sieving and settling are the oldest sizing techniques known. Sieving by square screens, shown on Figure l-A is a common, current practice for sizing particles both in the laboratory and in production. A woven cloth is used which usually has square openings. The size particle that will pass through the opening dependent on a complex relationship of its morphology. As can be seen in Figure l-A, neither the width nor the height of the particle is determined by sieving. From square screens one and only one parameter characterizing the particle size is obtained, that parameter is the radius of the sphere that will just pass through the given sieve opening. A variation of square mesh screen is the slot screens, shown in Figure 1-B. Here another measure more closely associated with the height of the particle is obtained. Once again, one and only one parameter is associated with the particles' shape.

Jan 1, 1977

By J. K. Hrica, T. J. Orr, J. Navoyski, B. Macdonald, C. L. Hoebbel, J. L. Bellanca, B. Demich

Haul truck fatal accidents and injuries continue to be a significant concern for the mining industry. However, the availability of high-quality training materials continues to be limited. Near-miss incident accounts, if packaged well, could help fill this gap, because for every fatality, there are hundreds of reportable accidents and thousands of undocumented near misses. Researchers from the National Institute for Occupational Safety and Health (NIOSH) collected detailed accounts of 21 near-miss incidents in virtual interviews with mineworkers at surface mining operations across the country. From these interviews, researchers created four simulation videos. The videos bring these events to life through first-person retelling and various visual perspectives of actual events. Each video exemplifies a critical safety message and a common haul truck hazard. This paper describes the process of taking narratives and turning them into impactful visual stories. NIOSH plans to co-release these simulation videos with the Mine Safety and Health Administration (MSHA) to the mining industry to raise awareness and ultimately help reduce haul truck-related accidents and fatalities in mining.

Feb 1, 2023

By Remo Grandori, Manfred Jaeger, Fabrizio Antonini, Luis Vigl

The EVINOS-MORNOS tunnel project with its 30 km of length is one of the longest hydraulic tunnel in the world realised with TBM method. The adverse geological conditions, the high cover and the short construction schedule were a great challenge for the successful construction of this tunnel. The paper will describe: the criteria adopted for the tunnel design, the selection of the construction methods and equipment, the productions of the 4 TBMs adopted and the comparison of the behaviour of the different type of TBMs in the various rock conditions, including special conditions, the characteristics of the adopted in situ and precast linings, a comparison between the foreseen and actual construction schedules, the contractual implications of realising a tunnel in such a severe and complex conditions.

Jan 1, 1995

By HONGWEI YANG, Lili Zhang

The oxidation behavior of copper smelting slag under non-isothermal conditions was studied by thermal analysis. The results indicate that the copper slag is mainly composed of fayalite ( Fe2SiO4) and magnetite ( Fe3O4). The oxidation behavior can be divided into two reaction stages with the increase in temperature; the first stage is the oxidation of fayalite to magnetite, and the second stage is the oxidation of magnetite to hematite. The two reaction stages cannot be strictly separated; that is, the reaction of fayalite is not complete, and magnetite has begun to transform into hematite. Based on the TG (thermogravimetric) curves, the ABS (Achar–Brindley–Sharp–Wendworth) differential and the Coats–Redfern integral methods were employed to investigate the oxidation kinetics of copper slag during the continuous heating process. The oxidation of fayalite into magnetite and amorphous silica phases occurs mainly in the temperature range of 673 to 1083 K. The activation energies calculated by the two methods are 193.69 and 195.52 kJ mol− 1, respectively. The reaction is consistent with Avrami–Erofeev equation, and the mechanism of oxidation is random nucleation and growth. The oxidation of magnetite to hematite occurs at 1083–1303 K. The activation energies are 308.79 and 328.77 kJ mol− 1, respectively. The mechanism conforms to the Jander equation and is controlled by the two-dimensional diffusion.

May 16, 2022

By R. D. Smith

The Bureau of Mines (BOM) evaluated the technology, capital investment, and annual operating costs of emission control for further reductions of lead in ambient air at the East Helena, Montana, smelter, and the Glover, Herculaneum, and Buick smelter-refineries in Missouri. This study seeks to analyze the technology available to the domestic primary lead industry for attempting to further reduce lead emissions below 1985 levels. Through enclosure of concentrate unloading and handling areas and all lead-processing buildings, followed by venting these enclosures to the atmosphere through baghouses and the application of appropriate local controls, emissions can theoretically be reduced by a total of 2,424 pounds of lead per day from 1985 levels at the three Missouri operations. Using conventional technology, aggregated additional capital costs of $250,014,000 and annual operating costs of $18,507,800 are estimated for the four operations, resulting in a total cost of $0.063 per pound of refined lead. Continuous drossing techniques would assist in meeting OSHA standards in process areas. Continuous drossing would change capital and operating costs to $258,344,800 and $16,104,700, respectively, for a total cost of $0.062 per pound of refined lead. First quarter, 1986 open market price for refined lead was $0.184 per pound.

Jan 1, 1986

Satisfactory means of managing growth in boom towns is a concern in mineral, energy and other large industrial developments. This session will include examinations of socioeconomic impacts, major issues such as social disruption, case studies, methods of managing growth, and concerns involving Indian lands. Innovative methods will be offered to assist the public, government, and industry in finding solutions to managing growth in rapidly growing communities.

Jan 1, 1979