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By S. C. Gambrell

The practice of roof bolting in world-wide mining activities is very well known, having been used extensively for over 50 years. The theory of roof bolting, however, is extremely complicated, and only recently have investigators attempted to explain the theory. Discussions of the mechanics involved usually originate with actual experience gained in the use of roof bolts. The use of roof bolting in mines has grown dramatically during the period after World War II. Other scientific techniques have emerged in mining research in the same period. Included in these techniques is the study of rock mechanics, which has now developed into an impressive research effort. Various means of analysis have been utilized in rock mechanics, most of which reduce rock to an isotropic, homogeneous medium that could be easily analyzed. Because of the inherent nature of rock, direct research methods frequently are not certain to provide satisfactory results, whereas indirect methods must idealize a given set of conditions in order to be useful. One of the indirect research methods is the photoelastic technique, the theory of which is widely known and needs no elaboration. This technique has been used extensively to examine the state of stress around underground openings of various shapes in certain types of strata, and under various configurations (1,2,3,4,5). Much of the theory used now in the design of underground openings is based on photoelastic evaluation. Unless rigorously applied, how- ever, the photoelastic technique is at best a qualitative means of evaluation. It is useful, however, for unusual examples which can be more or less easily analyzed to obtain the overall state of stress which could not be determined by other means. Little work has been done in the photoelastic analysis of rock bolting, mainly because direct research techniques have proven useful.

Jan 1, 1970

By J. C. Draper

The Duquesne Light Company and GAI Consultants, Inc. conducted a demonstration program aimed at establishing permanent vegetative cover directly on acidic, deep coal mine refuse. Several plots were treated with formulas varying in soil amendment application rates and plant species. Periodic monitoring of refuse chemistry has indicated when maintenance applications of seed and soil amendments were required. To establish drainage control, the site had to be regraded. The most successful formula was applied to the entire site. Specific treatment for acidic spots has been initiated. Results of the program indicate that adequate permanent vegetation has been established.

Jan 1, 1983

By K. V. Raj

"The development and advancement of computational fluid dynamics (CFD) has made it possible to better understand pollutant flow and distribution in deep open pit mines. Open pits located at higher latitudes, especially in the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during much of the winter. A three-dimensional CFD model of an actual open pit mine in the Arctic was developed to analyze the problem of pollutant growth during inversion, and mitigation of the pollutants through improved ventilation schemes. Due to the availability of mine-specific data, such as contaminant concentrations and coordinates of sampling locations, the actual 2013 pit geometry was used for model validation Concentrations predicted by the selected realizable ?-e turbulent model are compared to measured pollutant concentrations at the open pit. Pollutant concentrations at selected locations showed differences, but remained within the same order of magnitude in most cases. INTRODUCTION Computational fluid dynamics (CFD) has emerged as a useful tool for ventilation modeling in underground mines (Edwards and Hwang 1999, Purushotham and Bandopadhyay 2009, Wala et al. 1998, Xu et al. 2011). Application of CFD in open pit mines has been limited, however, since most open pit mines located at lower latitudes do not encounter considerable ventilation problems. Open pits located at higher latitudes, especially the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during winter. A number of Russian researchers have tried to understand the air inversion and resulting pollutant transport problem by modeling air flow phenomena in open pit mines (Baklanov and Burman 1996, Baklanov 1984, Baklanov 1995, Belousov 1985, 1989, 1995). Much of their work, however, was based on numerical models and methods of finite difference. Baklanov (2000) applied a modified ?-e and a ?-l CFD model to air flow phenomena on various terrains. More recently, Choudhury (2011) used the COMSOL CFD package for modeling pollutant transport for an idealized open pit mine. Collingwood et al. (2012a, 2012b) used a two-dimensional model for fluid flow and contaminant transport at an Arctic open pit mine. The authors have also previously presented work on CFD modeling of an actual open pit mine at high latitude (Bandopadhyay et al. 2014, Raj et al. 2015a). However, the CFD work done by the above-cited researchers lacked model validation with field-measured data. Validation of a developed model is important in assessing the quality and accuracy of the predicted results. In general, experiments are done numerous times in controlled environments to assess the validity of collected data. There are two types of assessments used in CFD simulations: (1) verification and (2) validation. Model verification is checking the accuracy of the computer codes during the implementation phase of a real-world problem, within the specific limits of accuracy (Oberkampf and Trucano 2002). Since, the pollution transport model presented in this paper used the commercial ANSYS-FLUENT CFD package, verification is not needed as the program has been tested widely, and verified numerous times."

Jan 1, 2016

By A. Santha Ram

The Indian Mining sector is subjected to a number of trends including call for global transition towards the route to sustainable development. Several regulations were enacted by the Government departments, from time to time, in order to identify the problems faced by the mining industry, including small-scale mining operations and to suggest appropriate mitigation measures in the form of environmental standards and certifications. During this process, a pursuit of sustainable development is regarded as an important area responding to socio-economic conditions, priorities and thus guides eventually corporate policies and practices. Thus, there is a need to formulate strategies for sustainable development. Based on these strategies some environmental indicators were developed in order to track down the progress and to evaluate its success. A case study pertaining to a group of iron ore mines in North Goa and Chromite mines in Sukinda, Orissa was selected for this study. Base line environmental data has been generated in the respective study sites. A core set of environmental indicators monitoring environmental progress based on the P-S-R model pioneered by OECD is linked with indicators for assessing the integration of environmental concerns.

Jan 1, 2003

By Gene E. McClelland, Dirk J. A. van Zyl

5.1 INTRODUCTION Heap leach cyanidation techniques possess considerable potential for exploitation of low-grade ores, small ore bodies, mine strip waste and tailing materials where fine grinding is not necessary for good extraction. For heap leaching to be successfu1, ore must exhibit certain characteristics, as previously discussed in Chapter 1. Primary among the necessary ore characteristics is that the ore must have good permeability after being crushed or treated and stacked into heaps if uniform distribution of the cyanide leach solution is to be achieved. Gold and silver ores containing excessive amounts of clays or fines generated by crushing are some of the most difficult to treat successfully by heap leaching. The presence of excessive amounts of slimes (generally classified as minus 50-micron or 270 Tyler mesh sieve size particles) in the heap leach feed will slow the percolation flow of the leach solution, cause channeling, or produce dormant or unleached areas within the heap. This may result in unreasonably long leaching periods and poor extractions. In extreme cases, the clays or slimes can completely seal the ore heap, causing the leach solution to run off the sides of the heap rather than to penetrate the ore heap. The problem of heap leaching ores containing fines can be aggravated during stacking and preparation of the ore heaps, because natural sorting of coarse and fine material occurs during these steps (Johanson, 1978). This phenomenon results in a concentration of ore fines at the center of individual ore piles and a concomitant concentration of larger rock fragments on the lower slopes and base of the piles. When the individual piles within the heap are leveled off prior to installation of the sprinkling system which delivers the leach solution, additional segregation occurs as the fines sift through the coarser ore particles. The segregation results in localized areas or zones with marked differences in permeability. As a consequence, the leach solutions follow the path of least resistance, percolating downward through the coarse ore regions and bypassing or barely wetting areas that contain large amounts of fines or slimes. Effective utilization of marginal gold and silver resources through heap leach processing requires the development of new methods in order to achieve more uniform size distribution during ore heap preparation and better slime control during leaching.

Jan 1, 1988

By Peter J. Tarkoy, Terence G. McCusker

INTRODUCTION The discovery of oil and gas reserves in the North American Arctic has led to substantial thought being given to their development. Systems adequate for exploration are not always, or even often, suitable for permanent installations. Combinations of offshore pipeline, drilling ships, platforms, sub-sea systems, sand islands and -ice island bases have been proposed. However, conditions in the Arctic are such that these methods may be difficult or impossible to implement. Problems exist with (1) the freezing of the Arctic Ocean surface for 9 - 10 months per year, (2) the movement of sea ice, (3) scouring of bottom sediments by ice islands and icebergs to great depths below the ocean bottom and (4) deep water channels. Any method which can avoid the problems associated with surface construction in these very adverse conditions merits detailed examination. One of the proposed solutions is to tunnel from a convenient or available access point to a point within the field, construct a chamber large enough to accommodate the drilling equipment and drill the development wells in a protected environment. Service and delivery lines would use the access tunnel and further tunnels and chambers would be constructed in a radiating pattern to develop the whole field. In order to determine the feasibility of underground construction in the North American Arctic, it is first necessary to understand the geologic and environmental factors which would affect such construction, to be knowledgeable concerning the problems and then to consider the techniques appropriate to the conditions which will be encountered, bearing in mind the need to minimize both con-

Jan 1, 1976

By John J. Mulligan

Coal is found in every major geographic region throughout Alaska and in two offshore areas. Since about 1852 over 100 small mines have opened and closed. Last years production was almost entirely from one mine in central Alaska. Clearly the utilization of Alaska's abundant coal resources presents political, economic and technical problems that are far from solution. Location and Physical Features Figure one illustrates the geographical and geological similarity between Alaska and western United States. The Arctic region of Alaska generally resembles Wyoming and the Dakotas. The Brooks Range is an extension of the Rocky Mountains. The Central region of Alaska between the Brooks Range and the Alaska Range bears a general resemblance to the basin and range country of western United States. The Southcentral and Southeastern regions has a similar resemblance to the Sierra Nevadas and the west coast of the United States.

Jan 1, 1982

By Cheryl M. McInnes, Graham J. Sparrow, James T. Woodcock

Three composites, assaying about 3 g/t Au and 0.75% Cu, were investigated. Each contained oxide copper minerals, iron oxides, and silicates. One composite also contained copper and iron sulphides. Maximum gold extractions by thiourea leaching were obtained after copper removal by acid pre¬leaching at pH 1.5 and redox potentials of 400 mV (Pt versus SCE). Best thiourea leaching conditions were pH 1.5, redox potentials over 200 mV, and 0.4% thiourea. This gave 90% gold extraction in 2 h with thiourea consumptions of 25 kg/t. Lower potentials gave poorer extractions. Ferrous iron additions before leaching halved thiourea consumptions. Longer leach times and the presence of sulphide minerals sometimes resulted in reprecipitation of gold.

Jan 1, 1989

By H. Para, A. Aguirre, G. Artadi

Mining is a very important economical activity in Peru which has been recently developed without considering environmental aspects. Here, we show an experience at the Milpo mine, situated 4,200 meters above sea level; a mining company that has the value of being one of few from the last decade that is engaged in consolidating a model of environmental protection. The model includes aspects of contamination prevention and control, with bioindicators such as pasture cultivation, vegetables, forests, and hydrobiological species breeding. Socially, through means of development programs in natural areas, forestation and support to rural agriculture, together with environmental education, it is being demonstrated that it is possible to ensure tangible results in environmental conservation and the well-being of the populations around the mine.

Jan 1, 1998

By W. S. Versluis, G. W. R. Kuzyk

Atomic Energy of Canada, Ltd. (AECL) is constructing an Underground Research Laboratory (URL), a major component of-the Canadian Nuclear Fuel Waste Management Program. In July 1988. AECL and the US Department of Energy commenced a cooperative research program that included extending the URL shaft by 190 m (623 ft) to the 443-m (1,453 ft) depth. The shaft extension, 4.6-m- diam (15-ft-diam), was excavated by full-face blasting using a burn cut. A Galloway stage accommodated the research activities and the sinking contractor's requirements. Blast designs incorporated controlled blasting techniques to minimize blast-induced damage on the shaft walls. The full-face method has been very effective, with 3.5-m (11.5-ft) rounds being advanced.

Jan 1, 1990

By Kefton H. Teague

History of the feldspar industry in the United States has been summarized by DuBois (I)*. The earliest production of feldspar in the United States is reported to have been from Mitchell County, North Carolina, about 1744, with the product shipped to England, In about 1825 several pegmatites were worked to a limited extent in Connecticut, with the production shipped to England. The first feldspar grinding facility was constructed about 1850 in Connecticut, with chaser mills used. Feldspar has been produced continuously in the United States since about 1870. Feldspar is produced from the following states: North Carolina, California, Georgia, Connecticut, South Carolina, South Dakota, Kansas, Oklahoma, Virginia, Arizona, and Wyoming. Total United States production for 1969 will amount to approximately 900,000 tons. The most current published figures for world production is 1966, at which time 2,165,000 tons was produced. It is estimated that world production of feldspar for 1969 will amount to 2,410,000 tons. Historically, feldspar has been produced by hand sorting and hand cobbing of coarse block feldspar obtained from the intermediate and wall zones of zoned pegmatites. In the United States the reserve of known block feldspar, recoverable by hand sorting is nearing depletion. More emphasis is now placed on feldspar sources contained in finer grained rocks, especially coarse granites or fine-grained pegmatite and beach, dune, and river sands from which the feldspar is obtained by beneficiation.

Jan 1, 1970

By David J. Akers

In past years, water drainage control in coal mines has been primarily directed on the basis of water quantity rather than quality. Due to the recent intense interest in total ecology and environment, emphasis has shifted to the point where the water exiting from a mining operation may be of better quality than when it enters. In most operations this has meant the use of treatment methods (neutralization) while the technology for the prevention of acid drainage is being developed or refined. To date, underground abatement of acid formation has generally been less expensive but also less effective than surface treatment of the mine water. It seems probable that total mine water pollution control will have to include both underground abatement and surface treatment methods. The general acid producing reaction involving the oxidation of pyrite - 2FeS2 (pyrite) + 702 + 2H20 ? 2Fe2S04 + 2H2SO4 - is well known, even though the individual steps are not clearly understood. The major implication of this reaction, that acid production can be eliminated by not allowing the contact of pyrite with free oxygen or water, has been well substantiated both in the laboratory (1,2) and in practice. (3) Underground abatement or control processes can be generally classified into two types: (1) the effective control or elimination of acid causing reactions within the mine, and/or (2) the reduction or prevention of water flow into and out of the mine. Recognizing the fact that these two types may be directly inter-related, this paper will, for the purposes of clarity and simplification, discuss each separately.

Jan 1, 1973

By T. Hayes

Track-type tractors remain one of the most cost-efficient stripping tools available to coal miners. Whether they are "sweetening up" a dragline operation with pre-benching or serving as the primary stripping tool, dozers can play an important role in driving down mining costs. This paper reviews the application zone of track-type tractors. In addition, it provides tips on site set-up, equipping of tractors, and machine operation which the audience can take home and apply.

Jan 1, 1996

By Max John

INTRODUCTION One of the main advantages of the New Austrian Tunneling Method (NATM) is its adaptability to varying rock conditions. This method is therefore successfully applied when complex geologic features are expected which cause uncertainties in the prognosis of the rock mass behaviour, as was the care at the Arlberg Expressway Tunnel. Furthermore, by employing the NATM problems are avoided when encountering varying geologic conditions or even extension fault zones along the tunnel, as was the case at the Dalaaser Tunnel and Perjen Tunnel. The NATM can also be used for rock and soil. The following examples will show how various rock conditions can be mastered. In accordance with the NATM all tunnels which will be discussed are road tunnels having a cross section area between 70 and 100 m2. The construction consists of a primary support, which ensures stress redistribution during excavation (Figure 1). The primary support is reinforced shotcrete strengthened by steel arches, when necessary, and rock bolts. When encountering rock pressure, swelling rock or soil, the primary support is suplemented by an invert arch. The purpose of the secondary lining is to increase the safety of the tunnel with regard to long-term stress redistribution processes or changes in rock mass properties as well as to protect the insulation. The secondary lining consists of cast concrete without reinforcement and is generally 0.25 or 0.30 m thick.

Jan 1, 1981

By Robert G. Benson, David M. Jones

The San Luis deposit of Costilla County, Colorado contains 11,021,000 tonnes (12,149,000 tons) of ore at 1.4 g/t (0.040 oz/st) gold in two mineable zones. Gold mineralization is associated with silicification and quartz-sericite-pyrite alteration localized in breccias along a low-angle "detachment" fault zone in Precambrian gneiss. Gangue minerals include chlorite, specularite, chalcopyrite, molybdenite, and fluorite. Mineralization is mid-Tertiary in age and may have an indirect genetic relation to the emplacement of felsic intrusions. Portions of the ore body are unconformably overlain by sedimentary rocks of the Tertiary Santa Fe Formation. The deposit formed during the early stages of extensional tectonism along the eastern edge of the present day Rio Grande rift.

Jan 1, 1990

By G. G. O. O. Uwadiale, M. A. Kollere, M. A. U. Nwoke

Birnin Gwari and Alawa graphite deposits were upgraded by flotation. Using 0.5 kg/t kerosene and 0.25 kg/t sodium silicate, flotation concentrates grading 90.7% and 88% Cg with recoveries of 86.2% and 84% were produced from Birnin Gwari and Alawa graphite samples, respectively. The combination of 0.5 kg/t kerosene, 0.2 kg/t pine oil and 0.25 kg/t sodium silicate yielded high-grade graphite (92.3% Cg) with a recovery of 83.9%. Flotation with refined rubber nut oil and kerosene, at a 1:1 ratio, produced a concentrate grade of 86.3% Cg with a recovery of 90.4%. With acid leaching of the flotation concentrate, a high-grade graphite concentrate containing 98% Cg was produced.

Jan 1, 1998

By Jon Y. Kaneshiro, Donald W. Scapuzzi

The primary purpose of the Prototype Installation Facility (PIF) for the Superconducting Super Collider (SSC) in this conceptual design was to test the magnets and other physics equipment. PIF was located in the northwest quadrant of the SSC 54 mile (87 km) main ring and consists of the first segment of tunnels, approximately 17,060 lineal feet (5.2 km) of 12 foot inner-diameter (ID) (3.7 m) tunnel, three 250 ± foot (60 m) deep shafts, connecting tunnels, and associated niches and alcoves. PIF would be the first portion of the main ring collider tunnel to be constructed. The geology, underground excavation conditions, underground facilities, and contractual considerations are discussed.

Jan 1, 1991

By M. ]. [Mohkam

The paper describes the features of the problems encountered and the countermeasures taken for two different tunneling projects. Where, slurry shields were used to excavate, in soft heterogeneaous water-bearing grounds, tunnels passing at very low cover beneath existing foundations of H.T. electric pylons, underground structures and major utilities. In order to avoid any ground failure and/or damage to the existing structures, one option was ground treatement by grouting or freezing technics. However, it was judged that, based on previous experiences, excavation with slurry shield could be carried on securely using an appropriate slurry enriched with polymers and applying a well determined pressure at ground face. A three dimensionnal limiting equilibrium analysis model was used to determine proper confinement pressures. And, the appropriate slurry compositions were stabilished based on laboratory test results. The tunnels were excavated successfully, no ground failure was experienced, and the maximum settlement recorded (on pylons) didn't exceed 3 mm.

Jan 1, 1991

By Dae S. Young, Eleonora Widzyk-Capehart

A quantitative estimation of the size distribution of rock fragments is extremely important in mining, metallurgy and other geotechnical fields. This paper presents a new approach to the analysis of fragmentation. The method combines the practicality of digital image processing of the rock surface with the theoretical volume calculations based on the principles and laws of fractal geometry. The final volumetric distribution curve is compared with the results from traditional sieving indicating close agreement.

Jan 1, 1996

By Gamal Rashed, Tim Miller, Nicole Evanek

High horizontal stress has been identified as a critical factor affecting roof stability in underground mines, particularly when the immediate roof consists of weak or laminated rock. Numerical models were employed to better understand the influence of caprock thickness, cutting sequences, and the orientation of driving direction relative to maximum horizontal stress on roof stability in underground stone mines. These models were calibrated based on field observations of roof falls from the study mine. The findings of this study enhance our understanding of roof stability under high horizontal stress and contribute to reducing the risk of roof falls in underground stone mines.

Feb 1, 2025