Search Documents

By E. Azrag, A. MacDonald

A hydrogeologic investigation was conducted to predict inflow to underground mine workings and mining-induced hydrologic impacts for a proposed underground mine beneath a lake in northern Canada. Flow and shut-in tests were conducted to determine hydraulic conductivity values and to estimate the hydraulic head. A conceptual hydrogeologic model was developed and incorporated into a numerical ground-water flow model (utilizing MINEDW, a three-dimensional, finite-element code with special attributes designed for mine dewatering). The mining sequence was represented in detail(e.g., driving ramps and drifts, extracting panels, and backfilling mined areas). Due to limited field data, a quantitative assessment of uncertainty was implemented to estimate limits of possible inflows.

Jan 1, 2003

By Jia-Shyan Shiau, Chung-Ken Ho

An uneven gas distribution through the burden layers inside a blast furnace (BF) results in abnormal gas resistance or pressure changes. Rapid variations in the abnormal gas resistance will lead to the occurrence of channeling. A visualization technology mainly made of pressure distribution was developed to predict BF channeling phenomena in this study. The real-time data of BF shaft pressure was used to create a 3D visual model by neural network algorithms and 3D real-time BF pressure changes were observed. The root mean square deviation (RMSD) of the BF shaft pressure was used as an index to set up the predicting criteria of channeling occurrence with the opening of BF Annular Gap Element (AGE), and a predicting system based on the criteria was built. The two criteria for the channeling alarm are the RMSD of the BF shaft pressure (> 0.15 kg/cm2 ) at the upper two levels, and the AGE opening being greater than 60%. This system has been installed in the China Steel Corporation (CSC) BFs, and the test results showed that a prediction can be obtained 8 to 16 min ahead of channeling allowing sufficient time for the operator to adjust the BF operation in order to avoid the occurrence of channeling.

By Tom Szaraz

Part of a major sewer expansion for the City of Columbus, Ohio. The Big Walnut Outfall Augmentation Sewer?Part II (BWOAS) consists of 13,200 feet of tunnel of 12-foot tunnel passing mainly through glacial deposits with a water head of up to 2 bar. A Lovat RME167SE was used to drive this tunnel with steel fiber reinforced precast segmental liner used for support. This paper will discuss the concepts for tunnel sup-port and TBM selection, the problems encountered with the TBM sealing systems and the solutions used to repair the machine.

By H. Walqui

The Empire concentrator currently processes magnetite ore from the Empire pit which is approaching the end of its mine life. Over the past two years plant wide tests have been run to access the plant capability of processing ore from the neighboring sister Magnetite pit. The neighboring pit presents challenges to the Empire plant due to its higher feed grade, finer liberation size and higher percent silica which require additional secondary grinding and concentrating capacity to achieve concentrate grade. The following paper summarizes the results from the second full scale test, run during 2009 under a challenging market environment

Jan 1, 2010

By Paul L. Boni

Trona, Na3(CO3)(HCO3) ? 2H20, is mined in quantity from saline facies of the Eocene Green River Formation of southwestern Wyoming. The Green River deposits are the world's largest known resource of natural sodium carbonates. An estimated 127 billion tons of trona ore are known to occur in beds exceeding 4 ft in thickness (Wiig and others, 1995). Twenty-five trona beds, exceeding 3 ft in thickness, and covering at least 100 mil have been identified. The beds are numbered sequentially in ascending stratigraphic order. Trona beds underlie more than 850 mil (bed 17) and are up to 37 ft thick (bed 1) (Culbertson, 1966). Five underground mines, operating in beds 17, 19, 20, 24, and 25, process trona to produce soda ash (sodium carbonate). A total of 11,837,703 short tons of soda ash were produced from 17.1 million tons of trona ore in 1997 (Kostick and Clark, 1998). A detailed study of trona bed 17, using techniques of petrography and X-ray diffraction, has been undertaken in the Solvay trona mine, near Green River, Wyoming. A continuous, vertical-channel sample was taken from near the production shaft for this study. At this location, bed 17 is 12.6 ft thick and includes several stratigraphic markers that are easily correlated throughout the mine and in surrounding drill cores. Bed 17 in this area averages 90% trona through its entire thickness (Wiig and others, 1995) and 95-100% trona in the lower two-thirds of the bed. Mineral impurities include water-insoluble dolomite, quartz, pyrite, clays, and other minerals and partially water-soluble northupite and shortite. Northupite, Na3Mg(CO3)2C1, contributes to chloride contamination in the soda-ash product and is concentrated in the upper one-third of bed 17, which is left behind as roof rock. Northupite has two modes of occurrence: (1) as bedded strata with dolomite, chert, clay, and shortite and (2) between primary trona crystals in trona spar. Petrographic and mineralogic data indicate that this section of bed 17 was deposited subaqueously during its early and late history and may have undergone periods of deposition in a subaerial or marshy environment. Stratigraphic data indicate that trona accumulated at an annual rate of 2-4 in. per year. During trona deposition, dolomite, CaMg(C03)2, precipitated in parting layers when new water entered the lake, freshening supplies of calcium and magnesium. The lack of clay minerals in the trona facies suggests water input may be by means of springs, as opposed to overland flow. Clay occurrences in thicker dolomitic partings within the trona facies indicate periods of episodic overland flow, possibly resulting from storms in the surrounding basin.

Jan 1, 1999

By J. H. Kempton

Refinement of environmental procedures can produce significant cost savings at most mines. Grouting permeable aquifers reduces water pumping and disposal costs. Stable groundwater quality supports reduced groundwater monitoring; and for contaminated groundwater, in-situ or natural restoration should be evaluated. Waste-rock characterization can be minimized using fewer (but more representative) samples, inexpensive surrogate analyses (e.g., NAG instead of humidity cells), and appropriate tests (e.g., avoid meteoric tests on sulfide). Selective waste-rock handling should be compared to random emplacement, which is often cheaper and more stable. Finally, incorporating schedule uncertainty in modeling allows the flexibility to revise mine plans within permits.

Jan 1, 2000

By Peter C. Badgley

Three tectonic provinces within the Cordilleran System, are analyzed in terms of tectonic framework. (1) Precambrian terrain of North-Central Colorado; (2) The Pacific Northwest; and (3) The San Andreas-Garlock fault system and associated features. In each case a close relation- ship is seen to exist between: (I) Arcuate mountain development; (2) Precambrian basement fabric; (3) Major fault patterns; and (4) Major mineral occurrences. The arcuate trends developed when the basement was still mobile. Later competent deformation rejuvenated pre-existing lines of weakness. Because of the pre-existing arcuate framework, the rejuvenated faults frequently act as conjugate shears (strike-slip faults) flanking the old arcs. The conjugate shears intersect to form wedge- shaped plates. When such plates move forward along boundary strike-slip faults in response to post basement orogenic forces, new secondary fracture systems are generated in the country rock flanking the advancing wedge. The apex regions of the wedges are particularly favorable for detailed exploration.

Jan 1, 1959

By Cary Hirner, Tony Cicchetti, Daniel G. Cressman, Jeff F. Wallace, Prapan Dave, Malcolm Sheehan

The City of Toronto is currently undertaking the design of the Black Creek Sanitary Trunk Sewer Relief Project. The Project involves the design and construction of approximately 20 kilometers of tunnel through shale rock of the Georgian Bay Formation and soft ground soil consisting of glacial till, glaciolacustrine and glaciofluvial sand, silt and clay deposits. The 20 kilometer alignment has been split into four sections of tunnel (1) the 12.9 km, 3.0 meter diameter Keele Trunk Relief Sewer, (2) the 2.9 km, 1.5 meter diameter Keele Trunk Relief Sewer Microtunnel, (3) the 3.9 km, 1.8 meter diameter Jane Relief Sewer, and (4) the 0.5 km,1.5 meter diameter Combined Sewer Overflow Storage Tunnel. Additionally, one 40,000 m3 wet weather flow (WWF) storage tank and numerous WWF connection shafts are to be constructed and connected to the Keele Trunk Relief Sewer to pick up WWF from existing outfalls currently discharging to Black Creek. The anticipated cost of the project is approximately $600 million with construction of the Project’s Phase One Works, the Keele Trunk Relief Sewer and Jane Relief Sewer, scheduled to commence in 2025. This paper provides an overview of the project in terms of the anticipated geotechnical conditions, the scheme developed for design and construction of the tunnel system and the associated schedule and procurement strategy. The consideration for planning of the tunnel system, the risk-based analysis and decision-making process are presented and form the basis for selection of a precast tunnel lining support method in the rock and soft ground.

Jun 13, 2023

By Victor Despointes, Stephane Polycarpe, Kathryn Kelly, Chris Feeney, Brian Hann, Vojtech Ernst Gall

The Pawtucket Tunnel is a 2.2-mi, 30.2-ft diameter CSO storage tunnel in Rhode Island. The primary tunnel is built using a dual-mode open-EPB TBM capable of sealing the face within 120 seconds to manage poor ground and water ingress which is launched from within a SEM starter tunnel. The main tunnel connects to four adits along its alignment, three of which are SEM tunnels and one being a MTBM tunnel. This contribution describes the selection process, potential risks, and requirements for the TBM, as well as the design of the main tunnel, the adits, and the adit-bored tunnel connections.

Jun 13, 2023

By K. T. Brashear, N. Ripepi

"Over recent years, specifically following the MINER Act of 2006, an increasing number of manufacturers of underground mine seals in the United States have begun using a form of pumpable cement or shotcrete to create barriers separating the working and abandoned sections of underground coal mines. This seal material, while generally considered to be homogenous and solid, contains a network of microcracks, voids, and delaminations. Generally, it has been assumed that methane (CF4) leakage around these seals is a result of movement around the boundary interface between the seal and surrounding strata. Using a perfluorinated tracer compound, perfluoromethyl-cyclohexane (PMCH), the movement of gases can be monitored through seal material to observe how gases move though the material, both intact and with faulting in the material. This paper documents two large experiments where the movement of PMCH was monitored in the field, along with modeling confirmation using 3D visualization software. INTRODUCTION According to a report in 2007, there were over 14,000 active mine seals in underground U.S. coal mines alone (Zipf, Sapko, & Brune, 2007). These seals are used for both ventilation and safety purposes, to direct the flow of air away from the abandoned area of the mine and to help eliminate the propagation of explosions that can occur on the outby side of the mine seal. The atmosphere on the outby side of these seals typical consists of low levels of methane that have the potential of producing leakage along the face of the seal on the inby side. Methane leakage around mine seals has historically been attributed to the permeability between the seal and mine interface (McPherson, 1993). According to the United States Bureau of Labor Statistics (BLS) between 2003 and 2012 an average of 17 deaths occurred annually in underground bituminous coals mines. The only time during the ten-year period where the fatalities were higher than the average was in 2006 and 2010, years which had three major explosions occurring in underground coal mines in West Virginia and Kentucky. Two of the explosions were propagated through the mine by seal failure or methane leakage around newly poured seals (Light, et al., 2007) (Gates, et al., 2006). These recent events, and new regulations regarding seal strength (MINER Act), have created a need to monitor the condition of underground mine seals. BACKGROUND Measuring the permeability of solid materials, such as concrete or seal materials, can be a valuable tool in the field of non-destructible testing (NDT). By using an inert gas, such as nitrogen, injecting the gas into a solid structure, and measuring the resultant flow rate and pressure differential, this can provide valuable information about the structure. Studies have shown permeability can be affected by the stresses applied to the structure, as well as temperature and moisture (Choinska, Khelidj, Chatzigeorgious, & Pijaudier-Cabot, 2007) (Abbas, Carcasses, & Olliver, 1999)."

Jan 1, 2015

The Bureau of Mines, U.S. Department of Interior, is currently investigating strata interactions associated with the mining of multiple coalbeds. Strata interactions due to subsidence are a result of undermining. This study involves underground investigations at a mine where room and pillar panels are actively being developed through an area of the Sewickley Coalbed which was subsided by undermining of the Pittsburgh Coalbed. Research to date indicates that undermining had little effect on upper mine pillar stability, but had a more severe effect on the development and maintenance of entries. Roof-to-floor measurements recorded over four times more convergence in entries developed over gob as compared with entries developed over support pillars in the lower mine. Consequently, this has led to major roof falls in the active panels, resulting in considerable production delays and supplemental roof support costs.

Jan 1, 1985

By Cory Bolen, Nadav Bar-Yaakov, Eric Zimmerman, Gregory Raines

The Chimney Hollow Reservoir Project broke ground in August 2021, constructing the tallest Asphalt Core Dam in North America, intending to improve reliability of drinking water supply to Northern Colorado communities. Aiming to expedite and streamline the geological mapping process in the tunnel, Stantec’s teams have developed a mobile and web-based GIS application for digital mapping input and rock mass evaluation, allowing real time decision making for assigning tunnel support class and resulting in a faster more efficient process. The following article presents and demonstrates the GIS mobile and web application-based process, the mapping results and review additional uses of the database created.

Jun 13, 2023

A virtual reality approach is presented that can aid entities such as mining companies and land use planners in communicating a visual understanding of a mining operation to interested stakeholders, citizens? groups, and public committees. These visualizations are particularly useful in permitting, production planning and mining closures, contributing to accurate communication and evaluation of mine plans, ultimate land use and evaluation of potential design options A case study is presented, that was created using commercially available virtual reality tools, to emphasize the benefits of visualization technologies in the sustainable development of mineral resources.

Jan 1, 2003

A group of geologists is located in a remote area of North America, without telephone lines, electricity or even running water. They have spent days accumulating data for a mining company that is eager to receive any information about the dig. But the team does not have access to a wired communications infrastructure. So the geologists must wait until they get to the nearest town to transmit their data. TMI Communications has a mobile satellite communication system that allows geologists in the field to transmit their data from remote locations. The company's satellite is the heart of its North American mobile communications network. This satellite turns all of North America, including Canada, Mexico and the Caribbean into a single digital communications cell. Traditional terrestrial communications systems, such as dedicated phone lines or cellular systems, cannot handle a remote geological exploration camp's extensive communications needs. Cellular technology, where available, has high costs and limited applications. For geologists in the isolated areas of North America, accessible and reliable phone service is vital to success. For those who have established temporary camps, TMI Communications' satellite phone service has improved the speed and accuracy of their communications with home base. This wireless network is suited to meet the needs of existing data applications and the challenges of new ones. It can support any one- or two-way, fixed or mobile data transfer. TMI's network enables geologists to transmit exploration results, spreadsheet information and location co- ordinates to anywhere in the world, at any time. This is important if a team needs to relay vital data back to its headquarters to support immediate decision making on a prospect site or a find.

Jan 1, 1999

By P. S. Baker

CRU estimates that the global supply of metallurgical grade alumina (MGA) grew by 5 percent during 2005 to a little more than 61 Mt (67 million st). About 30.7 Mt (33.8 million st), or 50.3 percent, of that originated from Oceania (principally due to the commissioning of the CAR refinery in Australia) and Latin America. In this context, Chinese production surged by 20.5 percent year-on-year to 7.7 Mt (8.5 million st) on the crest of a 17-percent rise in that country’s primary aluminium production. Meanwhile, on the demand side, there was a 6.7 percent climb year-on-year in global consumption to 62.3 Mt (68.6 million st). This reflected a healthy demand for primary metal from aerospace, construction, packaging and passenger transportation (to a lesser degree) in the United States, China, Brazil, South Korea and India. So there was an overall supply deficit of more than 1.2 Mt (1.3 million st). This, combined with an 18.3-percent diminution in closing stocks (down to 35 days of requirement), lifted the average spot price of MGA by 17.6 percent year-on-year to US$448/t (US$406/st).

Jan 1, 2006

By E. L. Smyth, A. Button

The apparent absence of significant Tertiary auriferous palaeoplacers in the Yilgarn Block of Western Australia can be explained by the dissolution of the placer gold into the highly saline, acid, oxidising ground waters which currently occur in upper portions of the palaeochannels proximal to the gold sources. The dissolved gold has then been redeposited in redox fronts further downstream. The placer gold is preserved in more distal portions where the ground waters are reducing. Exploration for these placers can be effective using the gravity contrasts that exist between the Tertiary sediments and the Archaean bedrock and SIROTEM which can detect the highest salinity zones which occur in the deepest parts of the channels. Final assessment of the gold content of the sediments must be determined by drilling.

Jan 1, 1989

By D. Kidd, T. Tucker, L. M. Indergard, S. Davis

"INTRODUCTION The Lisbon Valley Mining Co LLC (LVMC) operates the Lisbon Valley Mine located in SE Utah. The mine includes 3 open pits, 150-acre heap leach pad, and solvent extraction electro winning plant (SX/EW). Approximately 25MM tons of ore has been mined since 2005. The ore is stacked on the leach pad to an average height of 55 feet and occurs as a blend of crushed material (minus 2”) and run-of-mine (minus 24”). The host rocks include Dakota and Burro Canyon Sandstones. Copper occurs finely disseminated in this material at an average grade of 0.46%. Minerology is 63% sulfide, 27% oxide, and 10% insoluble. Total inventory mined through 2016 is approximately 230 MM lbs. METALLURGICAL CONSTRAINTS Copper production is constrained by areas of low permeability ore and geochemical issues, including acid consumption. The intrinsic permeability the ore ranges from 10-2 to 1 Darcy. This permeability does not permit sufficient aeration by natural convection, therefore oxygen transport is largely limited to the mass of oxygen that can remain dissolved in leachates. As a result, greater than 50MM lbs of copper remains in inventory and occurs secondary sulfides, including chalcocite, covellite, and bornite. BIOLEACHING FUNDAMENTALS Due to the higher activation energies of secondary sulfides, notably covellite and bornite, a strong oxidant is needed to remove an electron from the metal-sulfide lattice and release the copper cation into the sulfate solution. This process occurs most efficiently using the strong oxidant ferric iron (Fe3+). Ferrous iron can be oxidized to ferric iron by oxygen via chemical oxidation or biologically; which was measured to occur 500,000 times faster when using microbes versus oxygen.1 The microbes that oxidize ferrous iron (Fe2+) to ferric iron are naturally abundant and will develop biomass when appropriate conditions and nutrients present themselves. Most nutrients are provided by the ore/irrigation (P,N,Mg, Ca & Fe2+) while the others (O2 and CO2) are provided by air. In most cases, oxygen transfer is the rate limiting step during copper sulfide leaching. 1 Lacey & Lawson 1970 FORCED AERATION SYSTEM DESIGN This paper describes LVMC’s efforts to bioleach the remaining inventory by forced aeration. Two basic aeration systems were installed and tested including vertical wells and horizontal piping. Vertical System The vertical system was installed using the mine’s blast hole drilling rig. Wells were constructed using 4” high-density polyethylene (HDPE) connected to 4” polyvinyl chloride (PVC) screens similar to conventional bioventing wells. Ore samples were collected at each well location to characterize the spatial distribution of the remaining inventory along with fines (minus 200 sieve), pH (acid consumption), and iron. A block model of each analyte was developed and mapped in 3D."

Jan 1, 2017

By S. Y. B. Subbarao, K. Ravindranath

Lead and Zinc concentrates are being recovered at Rajpura- Dariba (Distt. Rajsamand, Rajasthan, India) from a complex multi metal sulphide deposit since 1984 by selective flotation employing a large number of reagents. The cost of concentrates' production has been high. Due to the increased availability of concentrates world over and to be competitive, it is necessary to reduce cost of production. An effort has been made by the R.D. Department of Hindustan Zinc Limited to bring down the cost by resorting to production of Bulk Pb + Zn concentrate with enough Ag to make it attractive to the smelters. This paper gives an account of open cycle testing and locked cycle testing in the Dowa Continous Mini Flotation unit. The metallurgical data generated in the mini flotation unit indicate the possibility of obtaining smelter-acceptable bulk concentrates containing Pb+Zn 45%, Ag 400 ppm and graphite carbon about 3%. An in-plant trial in the 3000 TPD concentrator indicated that there would be savings through dispensing with and reduction in some reagents, lower power requirement, etc. Also, a substantial increase in revenue is expected due to higher recoveries by resorting to bulk concentrate production as against individual concentrates.

Jan 1, 1995

By M. Javier

In business mining, dilution is the result of the operating parameters that occur too often and cause serious consequences to mine performance, questioning TO WHOM BENEFITS DILUTION. Mining persists in changing perception of real meaning of dilution. The lack of interrelation between mineral processes and nature compromises the understanding of dilution; this absence of interrelation occurs due to the misinterpretation of nature, otherwise, Geomimic could be helpful to filling the gap of misinformation. NATURE provides LIMITED metals in low content deposits; it is a challenge to obtain them. Nature never considers dilution. Furthermore, though dilution is a human concept, dilution is accepted and promoted. Reality of dilution is in its errors accumulation that translates into technology level or status applied in nature. It is doubtful that dilution can continue surviving if it is ?meaningless?. It will discourse: Is dilution illegal? If the change occurs in the prediction of mining will prevail a different destiny, it is important to touch the cores of the business; otherwise, it would represent repetition of the same ?negative? effects, as usual. Mining defines many losses during the disturbance of nature, from NPV elaboration to the metal recovery to commerce, demanding BETTER DESIGN. This paper introduces and applies MANAGEMENT BY LOSS, as first steps, to limit risks and uncertainties in mining. As result, the management of dilution will be obtainable under mining practices which promotes its character of SUSTAINABILITY.

Feb 23, 2014

By James W. Griffith, Sarah A. Riling

Bituminous coal dust was repeatedly placed into one lung lobe of anesthetized Macaca nemestrina monkeys using a flexible fiberoptic bronchoscope. Radiographs taken at 15 day intervals showed a focal radiographic density after 90 days time when a total of 1 gram of dust had been instilled. The radiographic density progressed slightly in size until 12 months by which time 3 grams of dust had been instilled and the animals were euthanized. At necropsy, the only significant gross lesion detected was the focal black pulmonary lesion located at the dust instillation site. Histologically, the lesion was composed of coal dust laden macrophages located primarily within interstitial tissue and interspersed with a slight amount of reticulum and connective tissue fibers. The distribution of coal dust was limited to the instillation site in the right caudal lung lobe based on radiographic, gross and histologic examination. Bronchoalveolar lavage of both right and left caudal lung lobes was performed 8 times during the 12 month long experiments without significant complications. More macrophages were found in lavage fluid from the right lung than the left, and most macrophages from right lung contained coal dust particles. Based upon a limited physical examination and complete blood count at 15 day intervals the animals remained normal during the experiment. We conclude that the primate lung's response to focal experimental bituminous coal dust resulted in a marked focal increase in pulmonary alveolar macrophages, which can be recovered regularly in high numbers by bronchoalveolar lavage. The model described has significant potential for investigating the pathogenesis of various respirable dust-induced pneumoconioses, for evaluation of new therapeutic approaches, and for refining experimental and clinical diagnostic applications of bronchoalveolar lavage. Key words: Coal Workers Pneumoconiosis, Disease model; Primate, Lung Lavage Fluids

Jan 1, 1991