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By D. Lee Petersen, Charles R. Nelson, Marvin Marshak

INTRODUCTION Construction is underway on a laboratory cavern 713 m below surface at the Soudan Mine, Tower-Soudan State Park, in northeastern Minnesota. The 13.9 in wide by 11.6 m high by 71.8 in long cavern will provide a laboratory space for basic research in physics, in which experiments can be conducted with greatly reduced interference from cosmic radiation. A first generation experiment, called the Soudan 1 detector, is currently operating in a converted drift 591 in below surface at the mine. The initial phase of the Soudan 2 detector will be an 1100-metric ton unit, which will occupy approximately a 19 m length of the cavern. Control and monitoring equipment will be in a prefabricated shop office enclosure erected in the cavern. The location and planned usage for the laboratory cavern present special excavation, lining, and outfitting requirements. Temperature and humidity control, a relatively clean dust-free environment, and a long service life are required. Low cost and risk to the owner were basic requirements due to the nature of the funding. The most common type of site selected to meet these two constraints is either an operational mine or a civil works facility such as a road tunnel. There are often serious problems for such laboratories because of ongoing operations such as blasting, hauling, etc. Most of these problems do not exist for the Soudan 2 laboratory because the mine is used as a historical site with regular tours only in the summer season. The laboratory owner, the University of Minnesota, and the park owner, Minnesota Department of Natural Resources, are both public agencies of the

Jan 1, 1985

By Y. J. Son, S. S. Nageshwaraniyer, K. M. Kim

"This paper reports on the development of a simulation-based framework for obtaining optimal blast design parameters for a hard-rock mine. To do this, a conventional medium-sized hard-rock mine was taken as a case study. The mine has two pits containing hard and soft rock types. The proposed framework contains a combination of regression analysis using Excel software by Microsoft and discrete-event simulation using Arena software by Rockwell Automation, applied to construct a model of the material-handling network of the mine. Specifically, blasting parameters are estimated by Excel-based regression analysis, processes including blasting and haulage from pits to crushers are modeled by a Forward Blasting simulation submodel, and material-handling operations including crushing, storage in stockpile, and haulage via conveyors and into SAG and ball mills are modeled by a Crusher to Ball Mill simulation submodel. A Reverse Blasting submodel is then used to obtain the optimum blast design corresponding to a target P80 particle size. Using the proposed framework, an economic analysis was performed to demonstrate the cost savings that could be realized for each rock type as a function of specific explosive energy. IntroductionIn a modern hard-rock mine, various processes such as drilling, blasting, crushing, grinding and mineral liberation are optimized to increase productivity, a practice known as mine-to-mill (MTM) optimization. Blasting is important in MTM optimization as it is the first comminution process and has an impact on all downstream processes (Julius Kruttschnitt Mineral Research Centre, 1996; Nielsen and Lownds, 1997; Nielsen and Malvik, 1999; Chung and Katsabanis, 2000; Kim and Kemeny, 2011a; Kim and Kemeny, 2011b).Two main research topics have emerged in the area of blasting design: (1) identifying the optimal target blast fragmentation at each shot and (2) controlling the blast fragmentation for that target. As part of an MTM optimization study, Kim and Kemeny (2011a; 2011b) developed a site-specific blast fragmentation prediction model that can be used to identify the target blast fragmentation and can be incorporated into MTM optimization. They also reported methodology for assigning model parameters easily and with minimal human bias."

Jan 1, 2015

By Robert Blair, David L. Fey, Stanley E. Church

Determination of the pre-mining geochemical baseline in bed sediments in watersheds impacted by historical mining activity is important in establishing watershed restoration goals. We have developed methods to solve this problem in the Animas River watershed, southwestern Colorado, using geomorphologic mapping to identify terraces that contain pre-mining sediments. Following a systematic evaluation of possible sites, we collected samples of pre-mining sediments in gravel deposits from 21 sites throughout the watershed. Geochemical analysis of individual layers has produced a chemical stratigraphy that can be tied to the historical record through geochronological and dendochronological studies. Analysis of geochemical data, when coupled with the historical record, clearly shows that there has been a major impact on the geochemistry in bed sediments in the active stream channel by past mining activities. Historical mining has resulted in a substantial increase in metals in the very fine sand to clay-sized component of the bed sediment of the upper Animas River, and Cement and Mineral Creeks, which are the major tributaries of the Animas River. Enrichment factors for metals in modem bed sediments, relative to the pre-mining sediments, range from 1 to 6 for arsenic, 1 to more than 10 for cadmium, 1 to about 15 for copper, 1 to more than 25 for lead, 1 to more than 10 for silver, and 1.6 to more than 12 for zinc. The pre-mining bed sediment geochemical baseline is high relative to average crustal abundance values of many metals. The Animas River watershed above Silverton, Colorado would be readily identified as a highly mineralized area suitable for mineral exploration if it were not disturbed by mining.

Jan 1, 2000

By Eberhard Werner

Existing reports on the effects of mine subsidence on water wells and springs appear to be inconsistent. Some report quick and complete recoveries to pre-mining conditions while others indicate long-term or permanent effects. It is clear that topographic and geological factors as well as precise position with regard to the mine are important in determining probable effects of subsidence on aquifers. Ridgetop aquifers which are well above regional base-level are much more susceptible to disturbance by mining activities than those located topographically lower. Effects seen are attributed largely to increased permeability, both horizontal and vertical. of the aquifer rocks. The deeper aquifers usually show short term losses or water-table declines. but the effects on the ridge-top aquifers persist for longer periods or may be permanent. Subsidence enhances permeability. so that infiltrating water moves much faster to lower levels. causing pond and stream losses and declining levels in wells as well as declining flows of springs of the higher aquifers, while increasing levels and flows of the lower aquifers. Additional effects are shifts of spring locations caused by minor tilts due to differential subsidence and redirection of shallow flows by changes of horizontal fracture permeability. These effects are seen as mining of a panel progresses beneath the site. and are often repeated when adjacent panel mining fronts pass the site. Analysis of water well level and spring flow records indicates that the effects are greatest at the edges of longwall panels in the tensional regime. These effects are amplified for locations close to topographically steep terrain and in close proximity to fracture traces mapped from medium-to small-scale aerial images.

Jan 1, 1986

By Ted Klemetti

Roof deterioration in weak moisture-sensitive rock leads to roof falls in coal mines. An observation site was set up in intake air at an underground coal mine in central Ohio to evaluate the time-dependent deterioration of moisture-sensitive roof rock. By periodically collecting and weighing the rock falling from the roof, the National Institute for Occupational Safety and Health (NIOSH) was able to quantify the deterioration of the moisture-sensitive shale roof. The measurements showed that more roof rock is falling in the dry winter months. Movements in an intersection were monitored in order to determine if deformation correlated with seasonal changes in temperature and humidity. The rate of intersection roof-to-floor convergence was found to be cyclical and related to seasonal changes, with more convergence during the months of April through September. At the study site intersection, the roof beam did not show deflection indicating movement most likely due to mine floor deformation. The bolt load also increased in the warmer months before shedding load, possibly due to rock failure. Temperature and relative humidity sensors, placed in holes in the roof show that mine air does not mix with the air in the holes. Consistent saturation levels of relative humidity were measured in the holes and it appears that high levels of moisture may have migrated into the bolt holes from roof shales. A roof sealant applied to a portion of the test roof appears to be preserving the roof and reducing the amount of rock fall into the entry, while the screened area virtually eliminated rock falling from the roof.

Jan 1, 2009

By W. E. Cobb

Mining companies, as developers of natural resources, are being forced to deal with the potential long-term liabilities of past, present, and future mining operations. As discussed in a previous paper (Cobb, et al., 1987), these liabilities can include solid waste disposal corrective action programs (state or federal actions), Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), (Superfund) (state or federal actions), or natural resource damage claims (typically filed by state agencies and provisions specified in CERCLA). These potential liabilities are very real, and should dramatically impact the way a company views its exploration and development programs, and operating mines.

Jan 1, 1988

By T. Brozell

"Communities near sand mines and processing facilities in Wisconsin have raised concerns regarding possible exposure to ambient respirable (PM4) crystalline silica. Fenceline PM4 (particulate matter captured with a 50 percent cut size of 4 micrometers aerodynamic diameter) crystalline silica concentration data were compiled at Fairmount Santrol Inc., Mathy Construction Inc. and U.S. Silica facilities. The long-term average PM4 crystalline silica concentrations ranged from 0.05 to 0.45 micrograms/m3 when sample values below the limit of quantification were treated as zeros. All of the long-term average concentrations were less than 20 percent of the Minnesota Department of Health’s and California Office of Environmental Health Hazard Assessment’s PM4 crystalline silica chronic reference exposure level of 3.0 micrograms/m3. The measured concentrations were consistently within the local background concentration range.Air Control Techniques P.C. compiled the sampling data using Thermo Fisher Scientific Inc. Partisol 2000i PM2.5 samplers meeting the requirements of 40 CFR Part 50, Appendix L. These samplers were adapted to capture particulate matter with a 50 percent cut size of 4 micrometers. The use of polyvinyl chloride filters allowed for crystalline silica X-ray diffraction analysis by NIOSH Method 7500. The combined use of adjusted PM2.5 filter-based samplers with Method 7500 crystalline silica analyses provided for a highly sensitive limit of quantification of 0.31 micrograms/m3 of PM4 crystalline silica.BackgroundIn 2005, the California Office of Environmental Health Hazard Assessment (OEHHA, 2005) adopted a 70-year chronic reference exposure level (REL) for PM4 (particulate matter having aerodynamic diameter of 4 micrometers or less) crystalline silica. The REL was extrapolated from occupational hygiene epidemiological studies, essentially all of which were based on in-plant PM4 crystalline silica measurements. No well-established ambient sampling technique for PM4 crystalline silica was available at the time that OEHHA adopted its REL. The personal samplers used for the National Institute for Occupational Safety and Health (NIOSH) Method 0600 in-plant sampling of employee exposure were designed for concentrations higher than ambient levels. The limit of quantification (LOQ) of PM4 crystalline silica on NIOSH 0600 filters was too high for the effective sampling of ambient air."

Jan 1, 2015

By Allan J. Breitenbach

Heap leach operations provide a low-cost method for recovering gold, silver, and copper metals from low grade ore materials. The processed ore materials are stacked in controlled lifts on a lined pad facility for heap leaching. A controlled barren solution is applied to the heap ore surface by sprinkler or drip emitter irrigation, and ore metals are leached into the solution for collection and extraction in plant process facilities. The leach pad and solution collection facilities are lined with impervious materials for containment of all process solutions. The liner system typically includes a composite geomembrane and clayey soil liner with a protective drain cover fill to maximize solution recovery and protect the underlying groundwater conditions. This paper discusses the types of pad liner systems currently used by the mining industry and the "good, bad, and ugly" lessons learned in engineering practice over the last 10 years in the design and construction of heap leach pads.

Jan 1, 1999

By R. L. Pearson

The 1987-88 Denver Brown Cloud Study was performed to determine the sources of the particle cloud which forms over Denver each winter. The study was organized under the leadership of Colorado Governor Roy Romer , EPA Region VIII and the Greater Denver Chamber of Commerce. The study was sponsored by over 40 organizations representing governmental agencies, the natural gas industry, the coal industry, utilities, oil companies, railroads, the motor vehicle industry, and other Denver area companies and organizations. The cost of the study was $1.5 million which was raised almost entirely from private sources. The study team was headed by Dr. John Watson of the Desert Research Institute of the University of Nevada. Dr. Watson is a recognized expert in conducting studies of this type.

Jan 1, 1990

By C. D. Elifrits

The required reclamation of land disturbed by surface coal mining often results in the creation of some over steepened slopes which are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has indicated that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations will be summarized in this paper and field results shown.

Jan 1, 1986

By Anuradha Khetwal, Tala Tahernia

The estimation of TBM utilization rate can be problematic due to the uncertainty involved in the tunneling system reaction to various geology along the tunnel. Moreover, the impact of operational and management issues on TBM performance is unsettled. This includes the occurrence and duration of downtimes and the uniqueness of projects relative to the geology, machine type, backup system, site setup, crew experience, and operational restrictions imposed on the project by localities. The CSM2020 is a model based on discrete event simulation that predicts machine utilization for single or double shield TBM. This model was developed by the Earth Mechanics Institute (EMI) team, using the database of tunneling activities which was compiled based on field observation and measurements in pertinent projects. In the current study, CSM2020 was modified to simulate the workflow of slurry TBMs. The operating principle of slurry shield TBMs is different than open-mode TBMs. The model was verified by comparing results with a recently completed project in the United States. As a result, the model offers reliable utilization rate estimation in different types of TBM by implementing appropriate workflow.

Dec 1, 2022

By Frank W. Schmechel

The subsidence monitoring program at the Old Ben No. 24 Mine was planned in 1976 as part of the on- going demonstration of longwall mining. The construction and installation of the network of surface subsidence monuments was started in Play of 1976 and completed four weeks later after which an initial reference survey was made of all surface monuments. Mining of the first longwall panel started in September of 1976 and was completed in May of 1977. Mining of the second panel started in August of 1977 and is continuing at this time. The Automatic Data Acquisition System (ADAS), which is the subject of this paper, was installed over the second panel on March 29, 1978 near the panel center (Figure 1) and approximately 104 meters (370 feet) in front of the face position at that time. Mine No. 24 is located approximately 5 kilometers (3 miles) Northwest of Benton, Franklin County, Illinois. Coal is being mined from the Illinois (Herrin) No. 6 seam which is at a depth of about 189 meters (620 feet) at the site. The Herrin No. 6 is up to 2.7 meters (9 feet) thick in the mine but a constant thickness of 2.1 meters (7 feet) is being mined by the demonstration longwall with both roof and floor coal being left for stability. Although the seam is flat laying at the mine, it dips north- ward regionally. Topographically, the surface over the demonstration panels is essentially flat and low laying with several areas of standing water. The Rend Lake Dam (United States Army Corps of Engineers) is about 305 meters (1000 feet) north of the demonstration site.

Jan 1, 1979

By Robert D. Schmidt

The Cyprus Casa Grande Corporation has provided Bureau of Mines researchers with an opportunity to investigate the hydrology of leaching an in place copper ore deposit. Hydrologic investigations of underground in situ copper leaching are being jointly conducted under a cooperative agreement. The hydrologic concerns of leaching operations at the Casa Grande mine focus on maintaining adequate solution injection and recovery rates, and on distributing the injected leach solution effectively within the ore deposit. Hydrologic considerations underlying these concerns relate to the permeability of the oxide ore zone during leaching, the unsaturated condition of the deposit prior to leaching, and the constraints imposed on in situ hydrologic design by the underground mine setting. The investigation involves monitoring of flow and pressure conditions in 58 injection and recovery wells, estimating permeability conditions using a hydrologic model, and on-site testing of hydrodilation and airlift pumping. Transient, fracture-controlled permeability is determined to be the dominant hydrologic consideration. A statistical modeling procedure has been developed for estimating changes in permeability during leaching. Flexibility in well design and operation is essential for accommodating the changes in fracture permeability that occur during leaching.

Jan 1, 1990

Modern coal cleaning technologies have allowed coal preparation facilities to become quite efficient at removing sulfur compounds, waste rock and low grade coals from run of mine coal. Up to 50% of the raw mined coal stream may end up as refuse, particularly when the coal originates from longwall mining operations, or is high in partings, rock and impurities. The refuse materials vary from coarse materials removed by physical screening to very fine materials removed by floatation and density separation processes. Coal refuse piles are also known by a variety of other names including "waste dumps", "gob piles" and "slate dumps". The potential hazards of improperly reclaimed refuse include contamination of surface and groundwaters by acidic leachates and runoff, erosion and sedimentation into nearby watersheds, spontaneous combustion, disturbance of topsoil borrow areas, and damage from landslides should large slope failures occur. Many of these problems have been particularly acute for abandoned refuse piles, and modern regulations attempt to minimize the environmental impact of coal refuse disposal operations.

Jan 1, 1993

By Steven J. Schatzel, James Addis, K. Vaibhav Raj, Berk Tulu

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to enhance methane control and mine ventilation practices at coal mines, as a method to mitigate hazardous work conditions. NIOSH researchers conducted case studies to investigate the effectiveness of existing systems and improve performance to decrease the potential for unplanned or excessive methane emissions. At one mine, drainage was influenced by hydrofracking inefficiencies where two of the six wells showed good frack development. Methane content was variable, from 300 ft3/t to 600 ft3/t. This paper also summarizes overburden movement during undermining and the estimated quantities of gas transported to the mine using FLAC3D and CFD modeling. The findings from this research effort highlight considerations based on specific mine conditions that may also be applicable to most longwall mines utilizing methane control systems.

Feb 1, 2025

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize biomass productivity, the influence of reclamation practices on biomass production must be well understood, which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass estimations and, also, the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, experimental biomass production plots on reclaimed mine sites established in Wise County, VA, are used for a comparative study of satellite spectral derivatives, which are evaluated against groundbased biomass estimates. Metrics based on four spectral derivatives, band ratios and spectral transforms were regressed against biomass measured in situ for different species. The results demonstrate that greenness and principal component 2 (PC2) were more efficient than the other spectral derivatives for monitoring the biomass of this reclaimed area. Also, it is shown that Landsat-5 TM has provided promising results for monitoring of the biomass changes occurring from 2008 to 2010 over the study area.

By R. J. McLaughlin

Acid mine drainage (AMD) can occur as a natural phenomenon through oxidation of sulfide minerals. Oxidation by air and water can be exacerbated by mining. Because AMD can exhibit low pH, it is capable of extracting heavy metals from mineral deposits. The result is highly acidic drainage with elevated heavy metal concentrations -the combination of which can cause extensive environmental damage. Because of the importance of these factors, this paper is focused on sulfate based AMD. Due to widespread mining, the occurrence of AMD is ubiquitous. As a result, several approaches to treatment have been developed. Chemical treatment using alkali is most commonly employed to treat AMD. There are alternative methods of treatment, as well as alternative ways of handling treatment sludges or concentrates. Dewatering of sludge or concentrates is beyond the scope of this paper.

Jan 1, 1996

By A. D. MacPhail

The Highland Valley Copper partnership was formed in July 1986 and was the logical result of a mine with a large ore reserve but no adequate mill, and a mine with a large, modem mill but dwindling ore reserves. The original partners -Cominco and Lornex -were joined in January 1988 by Highmont Mining Co. which contributed a two-line concentrator. During 1988/1989, the Highmont mill was moved 7.5 km to adjoin the Lornex mill, forming what is now called the Highland mill, with a current nominal capacity of 130 000 tonnes per day. The mine is located 220 km northeast of Vancouver, British Columbia and is close to four communities in which personnel make their home: Logan Lake, Merritt, Ashcroft, and Kamloops. The map in Figure 1 2.2 shows the general area. Kamloops is a major service centre and is serviced by two railways, two major roads and a regional airport.

Jan 1, 1993

By Michael J. Friedel

The permeability and flow capacity in unsaturated media is investigated by the Bureau of Mines for application to in situ copper leach mining at the Cyprus Casa Grande mine site. Moisture retention properties are derived and combined with scanning electron microprobe data to characterize the mineralogy, texture, pore size, distribution, and permeability of the host rock. Finite element modeling is used to derive a saturated permeability, ambient degree of saturation, and assess various injection-recovery schemes. Recommended design modifications for optimization of solution distribution and maximum recovery from the rock matrix requires either (1) the injection pressures on the order of 1500 psi and recovery wells operating in a suction mode, or (2) performing permeability enhancement, through rubblization. By producing a maximum block diameter of 4 m, injection pressures can be reduced to 500 psi with improved recovery and containment of solutions.

Jan 1, 1991

By M. J. Meulendyke

An extensive program of marked ball wear testing (MBWT), laboratory corrosion studies, and worn ball surface analyses has been used to gain insight about the role of corrosion in the overall wear process. In some environments, localized corrosion is observed; the actual wear mechanisms in such cases are pitting/spalling and abrasion. Factors affecting the occurrence of pitting include the abrasiveness of the ore, corrosivity of the slurry, corrosion resistance of the media, and galvanic coupling effects. Elimination of pitting substantially improves overall wear resistance. When pitting is not observed, the contributions of general corrosion are significantly less.

Jan 1, 1984