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By John H. Wright

The United States Antarctic Program (USAP), through its principal support contractor Raytheon Polar Services Co. (RPSC), has recently completed a three-year project comprising nearly 936 m (3,071 ft) of undersnow utility tunnels at Amundsen-Scott Station, South Pole, Antarctica. The tunnel serves the new station facilities that are currently under construction. It houses the piping that conveys fresh water from current and future water well sites, as well as waste water to repositories in abandoned wells. The undersnow tunnels permit year-round access for system operations and maintenance. The network of tunnels is entirely unlined and unsupported. And, for the most part, it maintains a rectangular cross section of 1.8-m-wide x 3-m-high (6 x 10 ft).The tunnel runs from 6 to 14 m (18 to 45 ft) below the surface. Eight 1-m- (3.3-ft-) diam raises bored from the surface serve the network as emergency escapeways.

Jan 1, 2002

By J. Stachurski, N. A. Abdel-Khalek

Laboratory Potation tests were carried out on six Polish coal samples of different rank. Each coal sample was screened into seven size fractions. The floatability of size- by-size for various size ranges for different samples was investigated as well as for the original samples. The results showed that in flotation of size-by-size, the intermediate sizes varied with the rank of the coal. Entrainment was shown to be an important mechanism in the recovery of fine particles in flotation of the original samples.

Jan 1, 1991

By K. Schonert

Jigging is a separtion process that has already been described by Agricola in 1556. Fine size material is normally treated in a hutch jigging process, in which the heavy particles are penetrating the jigging bed and are recovered in the hutch. In this process, a ragging consisting of the same or higher specific gravity particles is inserted upon the screen. The ragging is used mainly as a valve to maintain a constant upward flow of the water. Since the heavy particles should pass easily into the hutch, the ragging particles are up to ten times larger than the maximum feed size (1). In the fine size range - 1 mm the performance of jigs is mainly insufficient; some of the low density particles percolate the ragging while the hutch water flow prevents the fine heavy particles from entering the bed (2). By giving a thin layer of particles, which posesses a density sensitivity in case of certain adjustment of flow conditions, directly on the screen, the precision of separation can be increased. Stroke length and frequency have to be adjusted to give this filter layer a homogenous porosity between 60 and 70% during the pulsion phase, and the "en masse" lifting of the bed, as it is known in jigging of coarser material, has to be prevented (3). In this case, the jig cycle is only of minor influence.

Jan 1, 1987

By R. Reddy Kallu

Prior to July 2007, the only accepted method by MSHA for evaluating the mine seal design and performance is the full-scale explosion tests conducted in the NIOSH?s Lake Lynn Experimental Mine (LLEM) for deeming a seal design suitable for use in U.S. coal mines. Since the new regulations came into effect use of these conventional full-scale explosion tests for evaluating mine seals for the new elevated design standards may not be practicable. Generation of such high explosion pressures in experimental mines is dangerous and may cause permanent damage to the testing facilities. Further, they require significant amount of time, labor and money. Considering these factors, there is a need to develop scientific methods for evaluation of new seal designs and for understanding the dynamic seal response. This paper tries to address the reinforced concrete (RC) seal design using the three dimensional finite element based explicit software ABAQUS. Full-scale explosion test data available from NIOSH?s LLEM on 20 psi reinforced concrete seal is used for validating the numerical models. Further in this paper, based on the results from the validation models, a reinforced concrete seal is designed for 120 psi design standard for typical entry dimensions.

Jan 1, 2009

By A. Habibi

The FMC Westvaco Trona Mine is located near Green River, Wyoming and has an annual production of 4.5M tons. Trona is an evaporite mineral that is processed into several products, mostly soda ash. The underground mine has two active development panels and one longwall (LW) panel. The mining horizon is about 500m below surface and the surrounding strata liberates methane. Three surface-based, blowing fans provide ventilation air as a positive pressure system. The mine operates a 225m long LW face, built by Joy Mining Machinery. Headgate and Tailgate developments are driven with four entries. The recovery room, at the end of each panel, is 8m wide with three access chutes. Additional recovery room support comes for concrete blocks used with a center to center spacing of 1.5m. As the LW enters this pre-driven recovery room there are notable responses and shifting ground stresses. This study was undertaken to measure the ground response using seven vibrating wire displacement transducers. These devices were used to monitor the convergence as the LW approached the recovery room. The methane concentration in the air ventilating the recovery room was also monitored. The correlation between convergence and gas liberation was then studied. The results show that the convergence varies from 0.1m to 0.25m along the length of the recovery room. Ventilating the recovery room becomes critical as methane is liberated from oil shale as the more plastic floor material is disrupted. Appropriate methods are employed to ventilate the recovery room.

Feb 23, 2014

By Robert J. Pruett

The Georgia kaolin District is the world's largest producer of kaolin. Georgia production tripled from 2,344 million metric tons in 1964 to 7,570 million metric tons in 1994. Development of the Georgia kaolin industry can be traced to the mineral resource, the adoption of innovative process technologies, and the market growth for kaolin. Georgia kaolin is an abundant and high-quality resource that shows a range of advantageous properties. Technical developments in wet processing, delamination, and calcination allowed production of high-value products. The application of kaolin pigments to the paper industry provided a market that could absorb rapid growth.

Jan 1, 1998

By Laurindo De Salles Leal Filho, Arthur Pinto Chaves

The Serrana Process was developed in the 60's to concentrate an igneous low grade phosphate/carbonate ore using tall oil as a collector and corn starch as a modifier in alkaline medium. Nowadays, although tall oil has already been substituted by a new amphoteric synthetic collector, starch hasn't been substituted yet. This study is an attempt towards understanding the role played by corn starch in this specific system. By means of bench scale flotation test, it was observed that corn starch was capable of promoting the flotation of apatite, phlogopite and dolomite. No effect over calcite was observed. The best efficiency of separation apatite/gangue minerals was yielded at the concentration ranges of 17 to 20 mg/l of starch and 13 to 17 mg/l of tall oil. The starch concentration showed a strong influence over the characteristics of the froth produced by the flotation tests, mainly over the volume of the froth and its mineralization.

Jan 1, 1993

The implementation of NAFTA in January of 1994 was expected to have small but beneficial effects for the Mexican economy, mostly through increased investment flows. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results of the past two years have shown that it is governments and macroeconomic factors that influence investment flows, rather than the fine-tuning of trade flows through so called "free-trade" agreements.

Jan 1, 1996

By C. R. Tinsley

Valuations can be molded, twisted and misinterpreted. Cases of spurious scope setting; limits to the information or access by the valuer; difficulties with the lack of comparative valuations; inappropriate valuation methods and outright speculations are described. None should be accepted by an experienced, independent minerals valuer. The Australasian Institute of Mining and Metallurgy (TheAusIMM) is working on a Valmin Code for which a Manual of Best Practice and Valuation Guidelines may be developed.

Jan 1, 1995

By G. L. Mowrey

One critical element of the US Bureau of Mimes computer- assisted mining research program is the development of a reliable coal interface detection (CID) system. Several promising CID concepts currently being investigated by the Bureau include natural gamma radiation (NGR), vibration and passive infrared. To help establish which CID sensor technologies need to be developed for a given seam, coal and adjacent rock samples (immediate roof and floor) are being collected from selected major coal seams in the US and are being analyzed in terms of NGR and other geophysical measurements. This paper provides a brief overview of the Bureau's work in these CID areas.

Jan 1, 1992

By Johannes Jäger

"A composite shell lining typically consists of an outer permanent sprayed concrete shell, a water proofing layer and an inner sprayed or cast concrete shell. Composite shell linings become more and more popular and have been built recently on large scale infrastructure projects. Surprisingly there is very little published literature on the actual structural design of composite linings. As a consequence there is a lack of common understanding on how to design a composite lining structure. Composite action of the outer shell (primary lining) initially carrying short term ground loads and the “unloaded” inner shell (secondary lining) require nonlinear concrete modelling to be able to assess the bearing capacity of the composite lining structure adequately. The composite action of the waterproofing membrane and the inner and outer shells can be considered either by simplified closed form solutions or by numerical models. Strength and stiffness parameters of membrane and concrete govern interaction of inner and outer shell. This paper should contribute to understanding composite lining behaviour with focus on the bearing capacity at limit state by taking into account the actual loading history. Possible ways and concepts on how to deal with these topics are presented, however a broader discussion on limit states of the composite lining materials – also in the long term will be required to come to an agreement on composite lining design methodology. INTRODUCTION Composite Lining Technology Traditionally the construction of shotcrete lined tunnels incorporates primary and secondary linings, separated by a sheet or a sprayable waterproofing membrane. The primary lining shotcrete is considered to be structurally temporary and the secondary lining to be permanent, leading to designs which ignore the bearing capacity of the primary lining in permanent condition. There was general perception that the shotcrete lining installed immediately at the tunnel face, experiencing strains up to 1% and even cracking in the early age, combined with mesh reinforcement additional support measures like lattice girder, spiles and bolts cannot be considered as a permanent structure. But also former shotcrete mixes showed significant weakness with respect to durability suggesting a more temporary nature of primary lining shotcrete. On the other hand it was clear that primary lining shotcrete does not disappear, it may lose probably a certain percentage of its bearing capacity, but discounting any contribution from the primary lining at all was considered inherently conservative. There were different strategies to account for the risk of reduced durability and bearing capacity of the primary lining, either by selecting moderate ground loads for the secondary lining design, by assuming that some residual load will be carried by the primary lining. This approach is very much based on experience. Another more rational possibility is to assume that the primary lining degrades into a rocklike material, which is weaker than the primary lining shotcrete but still imparts some strength to the ground around the secondary lining, but does not need to comply with any concrete design codes any more."

Jan 1, 2016

By M. L. W. Tuttle, B. R. Berger

Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environ-mental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

Jan 1, 2004

By Hans G. Machel

In low-temperature diagenetic environments (0 c T c 60 - 80°C), elemental sulfur forms by six common processes: via (1) inorganic oxidation of H2S by molecular oxygen, (2) inorganic oxidation of H2S by ferric iron compounds, (3) polysulfide disproportion- ation; and via the microbial metabolic actions of (4) colorless sulfur bacteria, (5) colored sulfur bacteria, and (6) some types of thiobacilli. Economically viable deposits of native sulfur usually are formed by only one process: inorganic oxidation of H2S by molecular oxygen. The amount of elemental sulfur is also limited by three common processes that destroy it in low- temperature diagenetic environments: bacterial reduction, bacterial oxidation, and inorganic oxidation. In high-temperature diagenetic environments (80 - 10o°C c T c 150 - 200°C), particularly in sour gas reservoirs, there are seven common processes forming elemental sulfur: (1) SOdH2S reaction, (2) H2S- hydrocarbon reaction, (3) polysulfide disproportionation, (4) catalytic H2S decomposition, (5) C02-H2S reaction, (6) chlorinification, and (7) exsolution of physically dissolved elemental sulfur. Natural processes that destroy or remove elemental sulfur in such settings are hydrocarbon sulfurization, polysulfide formation, and advection. In most sour gas reservoirs, relatively small quantities of elemental sulfur occur as a free phase (solid or liquid). However, elemental sulfur often precipitates in copious amounts from the reservoir fluids via exsolution and polysulfide disproportionation during production of sour gas reservoirs. By extension, elemental sulfur may precipitate from reservoir fluids in relatively large quantities upon uplift and erosion of deep sour gas reservoirs, or from advection of sulfurous fluids into shallower settings via faults or other high-permeability pathways.

Jan 1, 1992

By T. L. Myron

In recent years increasing attention has been given to improving both the chemical and physical properties of sinter. The first step toward this goal was the production of a self-fluxing-sinter. More recently, blast-furnace operators have found that significant improvements in blast-furnace performance can be achieved by improving and controlling the physical size of the sinter. The results of full-scale blast-furnace tests have shown that blast-furnace production can be improved by using a closely sized agglomerate. The improvements obtained by the use of pellets, a closely sized agglomerate, are well known. In contrast, blast furnaces charged with sinter having a wide size spectrum have generally not yielded results as satisfactory as those from furnaces 1) * charged with pellets. Beginning in 1958, Appleby-Frodingham charged plus 3/8-inch sinter to their blast furnaces. Further tests by other companies in Canada, 2) the United States, 3) and Australia showed that blast-furnace production could be improved by about one percent when the plus 3/8-inch material in the burden was increased by one percent. Because of the promising results obtained with screened sinter, an extensive test program was initiated to determine an effective means of producing sized sinter in U. S. Steel's sinter plants. This paper describes the work done by the Applied Research Laboratory in this program.

Jan 1, 1965

By A. A. Davis

The decade of the 70?s saw a series of landmark environmental resource programs enacted by the Congress. Many states followed suit, so that by the end of the decade air quality, water pollution, and the conservation of other natural resources, including minerals, were the subject of a wide-ranging body of laws, policies, regulations, and procedures. Many of the actions required or permitted by this rule-making involved areas for which adequate information and substantial experience were not available. Moreover, goals and objectives were sometimes established which were enormously difficult to achieve technically, or of such formidable expense as to cause concern about their consequences in the marketplace. It is therefore hardly surprising that one product of all this activity has been a mass of litigation. Court dockets are crowded with suits and counter-suits involving both substantive and procedural aspects of environmental protection. Indeed, it is probably fair to say that the volume and range of environmentally-related disputes brought before the courts parallels that generated by the civil rights movement a decade ago. There were also some new dimensions to the environmental movement. For the first time, the national environmental policy act required agencies to prepare environmental impact statements when proposed projects or activities would have substantial impacts on environmental resources. Another requirement of many of the new programs mandated meaningful citizen participation in public decision-making. Here, as elsewhere, the purpose was admirable, but guidelines were vague, and the result often was inaction, polarization, and litigation.

Jan 1, 1986

By Richard V. Beck, Donald R. East, Jeremy P. Haile

In view of the increasing use of heap leach operations in the mining industry and the critically important performance of the leach pad liner in both the economic and environmental aspects of the design, it has become essential that the designer fully understand the factors affecting the performance of the liner. Minimizing the loss of pregnant solution through the leach pad liner is obviously of paramount importance to the economic efficiency and environmental compliance of the heap leach operation. Losses through the liner are a function of the hydraulic conductivity of the liner material and the hydraulic gradient across the liner. This applies to both natural and synthetic materials. The hydraulic gradient across the liner is a function of the build-up of solution above the liner, which in turn is determined by the permeability of the heap material, the slope of the liner, the drainage path length and the leachate infiltration rate. A relationship incorporating each of these parameters and their effect on the hydraulic head acting on the liner has been developed in terms of the Dupuit criterion, assuming one- dimensional flow with vertical accretion.

Jan 1, 1987

By Richard Switalski, Mark R. Kritzer, Boro J. Lukajic, Robert Pintabona

Ground freezing was chosen as an initial support method during construction of two deep shafts at the Mill Creek project. The Mill Creek, Phase 2 tunnel (MCT-2) is utilized to convey and store combined storm and sanitary sewage collected from the member communities in the greater Cleveland area. The main objective of groundfreezing was to provide a strong support structure to resist soil and groundwater pressures. This was achieved by creating a watertight, frozen-ground barrier around the shaft perimeter. The paper will provide an overview of ground freezing techniques applied during the construction of two shafts, each 250-feet deep.

Jan 1, 2003

By Bilgehan Kekec, Sertac Dündar, Niyazi Bilim

"Knowledge of the abrasion resistance of aggregates is important when using them for asphalt and concrete mixes and highway construction materials. In this study, the usability of natural building stone waste as aggregates for different engineering applications was investigated. To this end, test samples were obtained from a number of natural stone quarries and stone cutting factories. The abrasion tests were carried out on the test samples and results were compared between samples. The abrasion strength values were determined with both the Micro-Deval (MDe) and the Los Angeles (LA) abrasion test methods. A correlation coefficient was also determined between the LA and MDe tests results using an appropriate statistical model.Introduction The rapid consumption of natural resources has led researchers to work on the efficient utilization of such resources. To this end one can convert waste into useful raw materials, or determine alternative uses of the industrial waste materials. This has become increasingly important as storing or dumping waste may result in environmental problems. In addition, the use of industrial waste in a different application of the construction industry prevents rapid consumption of limited natural resources and can mitigate environmental problems related to raw material production, Industrial waste such as blast furnace slag, fly ash, building demolition material, marble waste and dismantled asphalt have been used as highway and concrete materials (Ahmed 1993, Ramaswamy and Aziz 1992, Schroeder 1994, Ceylan and Manca 2013, Holtz and Eighmy 2000, Hebhoub et al 2011). It is very important to analyze whether these aggregates are of the required quality in terms of their application and their economic life. This analysis can be carried out using various tests such as the Micro-Deval and the Los Angeles abrasion tests, sieve analysis, durability chemical resistance, peeling and adhesion, and freezing-thawing tests (Erdem et al 1996). Specifications for aggregates also include terms that define the grain shape, cleanliness and surface textures."

Jan 1, 2017

By Franklin H. Sharp, R. Woods

The operation of the Magmont Concentrator located on the New Lead Belt of Southeast Missouri is described. Ore characteristics affecting lead-copper-zinc separation are enumerated, and the cur- rent methods of separation are detailed.

Jan 1, 1976

By S. Luning

In the nineties the gold sector in Burkina became subject to internationally prescribed liberalization policies. The national state is at present only one of many players. Who are these players, and how are they involved with one another in organizing goldmining activities and prospects in Burkina? One mining site serves as a case to study the scope of players and the types of authorities they build upon in governing gold sites. What conclusions can be drawn in regard to the present position of the Burkinabe state within this field of governing authorities?

Jan 1, 2007