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By Ronald R. Rose

Currently six economic heavy mineral deposits are known on the Penholoway Terrace. These are (from south to north) the Green Cove Springs Mine (GCS), Boulogne Mine, Folkston Mine, Mission, Lulaton, and Ludowici. The GCS deposit is located to the west of Highway 17 between the towns of Green Cove Springs and Palatka in the state of Florida and has been mined since 1972. To the north, the erosion created by Black Creek restricts the northern extension of the orebodies and to the south a karst depression and erosion by the St. Johns River restrict southern extensions. The deposit is 20 miles long and up to 4.5 miles wide. Deposit thickness is from 5 feet up to 45 feet. The deposit is a series of regressive barrier island sequences deposited during the Pleistocene along the ancient Penholoway and Wicomico shorelines. The initial transgression of the ocean up to the location of the western Henry orebody was an extensive sea-level still stand as evidenced by the unit thickness and stacked transgressive regressive sequences. This period was followed by sporadic regressing seas and still stands, progressing eastward and stranding the sand bodies which make up the East Extended, TE, and East TE Ridge orebodies. The orebodies are underlain by predominantly non-mineralized fluvial sands and occasional back barrier lagoonal deposited clays. There is a predominance of wetlands on the southern extents of the zone as the surface elevations decrease due to a large karst depression.

Jan 1, 2005

By S. M. Moore

Each year more than 400 coal miners are injured (fatally and nonfatally) by rock falling from between or around roof supports. Many of these injuries can be prevented by the installation of roof screen. However, many coal mines are reluctant to use roof screen because of the added cost. The goal of this study was to determine the potential savings in workers' compensation (W C) premiums that can be achieved due to a reduction in rock fall injuries after roof screening. The WC rate-setting methods utilized by Illinois and Kentucky were investigated in this study. Using data obtained from the Mine Safety and Health Administration, national and state WC bodies and individual insurance companies (e.g., average cost per injury, loss cost rate, number of injuries per year, number of injuries preventable each year with roof screening), baseline mines (representing two mine sizes: 67 and 150 employees) were constructed with realistic ranges for estimates of injuries and WC premium costs. Using each state's actual WC rate-setting formulas, a sensitivity analysis was conducted to determine the total savings in WC costs after a three-year period. Annual savings in WC premiums ranged from $41,000 to $326,000 for the 67-person mine, and $96,000 to $843,000 for the 150-person mine. An economic analysis of the cost of a roof screening program at a 67-person mine was also conducted. The annual cost of a roof screening program here was estimated at $240,000. At this mine, the reduction in WC premiums alone could pay for the entire screening program.

Jan 1, 2010

By William E. Mead

A regional investigation to find large supplies of potable ground water was carried out at elevations exceeding 12,000 feet above sea level on the Bolivian Altiplano. The program marked the first application of modern ground water search and development technology in the region, and ended a history of unsuccessful exploration efforts to locate important supplies of fresh water from underground sources. Oruro, a population center of 90,000 inhabitants, and its primary supporting industry - mining, both derived major direct benefit from the results of this program.

Jan 1, 1970

By S. K. Sahoo, S. K. Sharma, A. Yadav, B. Behera, G. S. P. Singh

A field representative modeling of the gob behavior is critical for the understanding of the associated mechanics of strata behavior in longwall workings. The findings of theoretical models and laboratory tests on the simulated gob material have shown the strain hardening behavior of the gob material. The double-yield material model, which is a built-in constitutive model in FLAC3D, has significant potential to simulate the gob compaction process as it represents materials which undergo irreversible compaction in addition to shear yielding. Apart from this, several researchers have attempted using modified elastic model or applied nodal force in reaction to the strain in the gob area as per the well-known theoretical relations to meet this requirement. Although these models can simulate the mechanical response of the gob for subcritical and critical extraction widths, they do not apply to supercritical extraction width as the gob stress may exceed the in situ stress level in such cases. For overcoming these limitations, a standard approach has been developed and validated in this paper, which can be used for simulating the gob behavior in supercritical longwall workings as well. The complete study is divided into two stages wherein the laboratory scale compression test on the simulated gob material has been numerically replicated to develop preliminary confidence followed by a parametric study of the double-yield constitutive parameters for a rational estimation of their values in different conditions. The calibrated model has been used for verifying its results by plane strain modeling of two different longwall workings, using well-established empirical and analytical findings and field observations. The approach suggested in this study can be used for the efficient modeling of the gob behavior of longwall panels under varying geo-mining conditions without compromising the accuracy of the numerical model. The meticulously validated model can be helpful in rational estimation of stress redistributions around the gob area apart from load transfer on the barrier pillar.

By Roy A. Grancher

?The Horn of Plenty seems to have sprung a leak?.? anonymous For the first time in the Nation's peace-time history, shortages have become a way of life for the United States. Such words as scarce, tight, and critical are used in regard to supply, leading to priorities, allocations, and possible rationing as make-shift attempts to satisfy demand. Almost every day a new type of shortage appears in another product area that has traditionally been taken for granted as being in perpetual abundance. The range of coverage extends from basic commodities such as oil, chemicals, cement, steel, copper, cotton, etc., through to machine tools, motors, bearings, electronic components, etc. , to those finished outputs that satisfy our fundamental requirements for food, clothing and shelter. Signs of the times appear in cancelled airline flights, unfilled lines at gasoline stations, no available home freezers, lengthy delays in any furniture deliveries, or to that little old lady seen walking out of a local supermarket clutching her hoard of twenty rolls of toilet paper. What a sad commentary to have to make about our Land of Plenty, so long the envy of the World for its material wealth -- and today with its initials "U. S." seemingly standing for ?Unlimited Shortages.?

Jan 1, 1974

By C. R. Fahnestock

One of the major problems for us in the earthmoving industry is the analysis of materials under the ground surface. Countless engineering and construction jobs would be simplified if there were an inexpensive and fast way to obtain information on problems such as: Depth and solidith of bedrock? Nature of the materials between bedrock and the surface? Adequate foundation for bridges and drainage structures? Location of supplies of materials to be used in construction? Investigation of tunnel sites? Characteristics of swampy areas and investigation of existing and potential slide areas? These questions are of paramount interest to highway contractors as they bid jobs and plan, equipment spreads to handle them at optimum efficiency. Such information also is invaluable to engineers in the design and construction of bridges, buildings, railroads, canals, and tunnels.

Jan 1, 1961

By L. Adler

A systematic, balanced and inclusive formulation of the vast input data for mine design is presented. Since the quality of this statement severely influences subsquent design it is extremely important to senior mining engineers and the profession-at-large. If unfocussed, chaos can result along with serious ommisions. The basic categories, each a traditional one are: 1) Natural Conditions (geology and geography), 2) Company Capabilities (monetary and managerial), 3) Public Domain (regulations, contracts, good will, etc.) and 4) State of Art (mining engineering professionalism). To further reduce the data additional organizing principles were used: the distinctions of mining (vs. civil) engineering, proceeding from the general to particular, the basic engineering dimensions, and separating dependent from independent variables. The results are a unique and unified corpus, which anticipates the mine design procedure.

Jan 1, 1987

By K. Kim, T. M. Yegulalp

A new explanation of the scale dependency of rock strength is presented based on the theory of extremes. A brief review of past work on specimen size and strength relationship is followed by an introduction to the fundamentals of the underlying theory of extremes and its relationship to the scale effect. It is shown that the weakest link theory is directly related to extremal statistics and that parameters of strength distributions of rock can be derived as a function of the specimen size. Three sets of Brazilian test data are used to demonstrate the use of this approach.

Jan 1, 1994

By Hilal Soydan, H. Sebnem Düzgün, Jurgen Brune

In this study, with the primary goal of capturing ongoing digital transformation and automation impacts on the mining industry and its workforce, we conduct several interviews with mining industry experts in the United States and analyze our survey reports qualitatively and quantitatively through exploratory analysis. After the interpretation of the insights of industry experts, we proceed to generate a personalized and customized data analysis through a novel metric based on skills, knowledge, competencies and occupational requirements, which quantifies the job similarities for occupations in the mining industry based on the publicly available database of the U.S. Department of Labor. We use text analytics to tokenize and classify the interviews to capture a better understanding of major response categories. The temporal analysis shows that the critical competency needs in the data science and autonomy category increases from 28 percent in current demands to 43 percent. In defining our metric, we also calculate Kullback–Leibler (KL) divergence for each job profile that enables determining whether and to what extent that job is transitionary in our test set based on the mean, standard deviation and kurtosis of each job of interest. Our analysis reveals that the in-group job transitions are significantly easier than the between-group transitions, proving our initial assumptions and common sense. The generated heat maps provide the opportunity to present the gap between the current job and desired job profiles that provide feasible career change options, among others, offering individualized career paths for job seekers and promoting potential job transitions. Through the collection of industry-specific individual employee data, the AI system is envisaged to continue to learn as end users engage with the system, thus creating a central data hub specifically for the future workforce in the mining industry. Although the study has limitations on generalizability for qualitative assessments, it presents itself as a valuable application of how qualitative and quantitative approaches could be of value for future worker training in the mining sector.

Feb 1, 2025

By John K. Liu

The trend to larger grinding mills, requiring total drive power in the range of 10,000 KW(13,400 HP) or so provides the incentive for developing new power transmitting techniques, since conventional girth gears are limited to about 3700 to 4500 KW per mesh (5000-6000 HP). For the immediate future, the synchronous motor, with its beneficial power factor, and the squirrel cage induction motor, with its high reliability record and low maintenance, still promise to be the best choice for prime mover(s). Due to the abovementioned single mesh power limitation of the gear train, however, two or more motors must be combined to attain the required drive power. This paper describes a scheme for coupling these motors to the mill using a straightforward, essentially mechanical means that is based on proven components and controls.

Jan 1, 1977

By J. M. Mercier

Approximately seven (7) years of recent intensive mining activity in the Wasatch Plateau Coal Field of Utah has revealed distinct geologic patterns which, at times, profoundly influence reserve estimates, coal quality, mine layout, and reserve accessibility. Mine planning, economic feasibility, and resource recovery activities by Getty Coal Company utilize a multi-faceted approach by necessity when evaluating Utah properties. Two specific operating mines offer examples of the affects of adverse geologic conditions on mine operation and project economics.

Jan 1, 1984

This paper describes major technical developments in rod mill design and operating practice since its introduction into the North American minerals industry over fifty years ago. The basic operating characteristics of the wet, overflow rod mill are described, and significant operating variables are reviewed in terms of their effects on mill power draw, power efficiency, and practical aspects of circuit operation. Key factors for improving the economic performance of rod milling circuits are identified.

Jan 1, 1986

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 Peiwei Xiao, Xiang Li, Biao Li, Haoyu Mao, Nuwen Xu

As an advanced method of rock engineering construction safety monitoring, microseismic monitoring technology can monitor the micro-fracture of rock masses within an effective range, and then perform forecast analysis of rockburst, cracking, falling blocks and other disasters. Although the application of microseismic monitoring technology has become more mature, how to improve its application efficiency remains to be further studied. At present, artificial intelligence has been extensively developed, and the use of intelligent algorithms to improve the efficiency of rockburst forecast can provide a valuable reference for the safe construction of underground engineering. To this end, this paper proposes a microseismic multi-parameter rockburst early warning model based on dynamic Bayesian networks. First, the sensitivity of microseismic source parameters to rockburst forecast is analyzed based on microseismic monitoring data and actual rockburst information of a hydropower station. Second, the main seismic source parameters and their data are selected and imported into a dynamic Bayesian network for learning to obtain the rockburst forecast model. The model is confirmed in its self-validation and K times cross-validation, and the receiver operating characteristic curve of the model is also analyzed, it is found that the area under the curve is close to 1, indicating that the model has good accuracy. Finally, the analysis of the influence strength of the parent and child nodes in the model reveals that the moment magnitude and source scale are the most sensitive parameters, which can be used as an important reference for rockburst forecast.

Apr 26, 2022

This paper provides a summary on the use of the POL YCOM high pressure grinding roll (HPGR) for increasing extraction in copper leaching. The energy-efficiency and significant hydrometa1lurgical benefits of the HPGR result in better acid-curing, higher solution application rates, improved copper extraction from various copper minerals and better recovery from high acid consuming ores. The HPGR's metallurgical features such as micro-fracturing, better liberation of disseminated and veinlet copper, increased oxygen and lixiviant penetration lead to higher copper extractions than achieved by conventional crushing. Flowsheet options, operational characteristics and applications for various copper ores are outlined.

Jan 1, 1996

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979

By R. W. Utley

Over one half billion tons of coal per year is scalped, classified, deslimed, drained and rinsed, dewatered and final sized on rotary, vibrating, shaking or stationary screens. The vibrating screen is the industry work horse and performs the bulk of the screening functions in the coal preparation plant. There are two major types of brute force mechanical vibrating screens used in coal preparation plants: (1) the two-bearing one-shaft inclined screen and (2) the four-bearing two-shaft horizontal screen. Both of these types are familiar to coal producers.

Jan 1, 1966

By Roshan B. Bhappu

Stimulated by current $0.80 to $1.20 per pound price tag of copper, considerable interest and activity have been generated in the copper mining camps throughout the world, and especially in the Southwestern United States and Northern Mexico copper belt. Under these economically favorable conditions, many of the marginal oxide-copper deposits, as well as newly discovered prospects, are under scrutiny for possible exploitation. For both the known deposits and new prospects, the big question facing the mine operator is the selection of the best method for processing these economically attractive oxide-copper deposits. Several variations of the hydrometallurgical processes are currently available for treating oxide-copper ores which can be mined by the open-pit method. Basically, these processes involve preparing the ore for application of an acid solution, applying the solution to the ore, and recovery of the metal from the pregnant solution. Dump leaching, heap leaching, vat leaching, agitation leaching and, in more recent times, in situ leaching or solution mining in combination with well established cementation process or the newly developed solvent extraction-electrowinning system have all been employed or have been investigated for the recovery of copper from oxide ores. Of these processes, dump, heap and vat leaching have been successfully practiced for treating oxide-copper ores. Agitation leaching is a relatively newcomer and has been adopted from the experiences of uranium and gold processing. Finally, the inplace leaching technique is the latest process to be suggested for possible treatment of oxide-copper ores.

Jan 1, 1974

By Jeffrey A. Yonkey, Timothy J. Lutz, Jacob L. Carr, Christopher C. Jobes

"Since 1984, there have been 39 fatalities involving striking and pinning of the operator and other workers by the continuous mining machine (CMM). In January 2015, the U.S. Mine Safety and Health Administration (MSHA) finalized a regulation to require proximity detection systems on all continuous mining machines except full-face machines (MSHA, 2015). Proximity detection systems are designed to stop machine motion to protect miners from striking/pinning hazards. Several MSHAapproved proximity detection systems are commercially available.NIOSH researchers have been involved in the development and testing of proximity detection technology since creating the HASARD system (Schiffbauer, 2002) and have recently conducted research intended to develop more advanced proximity detection technology for CMMs (DuCarme et al. 2013; Jobes et al. 2012; Carr, DuCarme et al. 2013 and Carr, Li et al. 2013). In addition, NIOSH has also conducted research investigating how the signals of a proximity detection system propagate (Li, Carr et al. 2013 and Li, Jobes et al. 2012) and have developed a novel method for determining the location of a personal wearable device (PWD) relative to the magnetic field generators (Carr et al. 2010 and Jobes, et al. 2012).To evaluate the performance of proximity detection systems implemented in industry, NIOSH researchers conducted tests in 2013 on three systems installed on CMMs at three underground mines in Illinois and West Virginia. The results of these tests indicated that, while generally consistent performance was observed, there were opportunities for improving performance. These results were presented at the 2014 SME Annual Meeting (Carr, Lutz, et al. 2014). Since that time, second-generation systems have become available to the industry and are becoming more commonly used.Beginning in early 2014, NIOSH researchers conducted underground testing of these secondgeneration proximity detection systems installed on CMMs. Five tests were conducted on four installations of second-generation proximity detection systems, with one installation being tested twice. The tests were conducted at mines located in Illinois, Virginia and Kentucky with seam heights ranging from 137 cm (54 in.) to 213 cm (84 in.). These tests were conducted using the same test protocol used during first-generation testing, which is summarized in the following section."

Jan 1, 2014

By D. Gatzemeier

The Jewett mine is a surface mine in central Texas, producing about 8,000,000 tons/year of lignite. The mine covers 46,000 acres of land. Approximately 430 people are employed by Northwestern Resources Company and through their efforts, the Jewett Mine is one of the most productive mining operations in the country. The Jewett Mine utilizes a unique structure of staff to convert Operations Research into plans which can be implemented at the "front line" level of the Operations Team. This planning not only makes the mine cost effective and efficient, but promotes creativity in mining, which promotes ongoing research to lower the cost of mining.

Jan 1, 1993