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By Alan R. Grant

Interpretation of presently available geological information indicates that most of the periods of significant metal deposition in the Washington Cascades Range are, at least in part, genetically related to late Cretaceous -Tertiary intrusive episodes. Chemically, the most favorable environment for base metal deposition is high in potassium. Characterizing the advanced stages of these chemical alteration conditions are the silicate mineral assemblages orthoclase and/or secondary biotite. Wall rock alteration includes both deuteric and hydrothermal processes, the intensity of which primarily depends upon the degree of fracturing in the country rock prior to the introduction of secondary material. Broadly speaking, the primary physical controls for the distribution and concentration of sulfides appear to be a series of structural couples involving both northwest (paralleling regional trends) and northeast--striking systems. Meaningful base metal exploration in the Washington Cascades demands a basic understanding of the various geologic factors related to the distribution of the sulfide deposits. Any geologist contemplating Cascade work should be well grounded in the fundamental concepts of petrology and structure.as these constitute two of his most beneficial aids. The acquisition of the detailed data necessary for this understanding may seem a bit academic, yet it has been demonstrated in numerous instances that a fair economic appraisal of a particular property or mining district depends primarily upon the ability of the geologist to recognize the subtle environmental differences which could lead to the discovery of a major ore deposit.

Jan 1, 1971

By S. K. Mishra, S. B. Kanungo, D. Biswal

An attempt was made to beneficiate low-grade, high-phosphorus manganese ores of the Garividi-Garbham region of Andhra Pradesh, India, by using wet high-intensity magnetic separation (WHIMS). The distribution behavior of both mass and chemical constituents in different size fractions of a typical highly weathered ore sample was studied to obtain information about the liberation characteristics of various chemical constituents. Magnetic separation indicated that in the +208-µm size fractions, P and acid insolubles were concentrated in the magnetic fractions. However, in the -208-µm size fractions, P and acid insolubles were concentrated in the nonmagnetic fraction because of a lower recovery of the magnetic fraction. Variations in field intensity between 1.3 and 1.75 T had little effect on the recovery and the grade of concentrate. The results also demonstrated that phosphorus was associated with all three major constituent phases, namely, oxides of Mn and Fe and aluminosilicate gangue minerals.

Jan 1, 2000

By S. S. Peng

A hybrid boundary element-finite element model was formulated to model roof bolt reinforcement of the roof strata with bedding planes. This model was used to analyze the stress distribution around a rectangular opening with variables such as opening width-height ratio, number of bolts installed, number/location of bedding planes, in-situ stresses, etc. The most critical areas are identified and the number and length of roof bolt required are then determined. Two case examples are illustrated.

Jan 1, 1989

By Steve Kral

The Underground Construction Association?s (UCA) 2014 North American Tunneling (NAT) conference is expected to attract about 1,000 tunneling and underground construction professionals. With the theme ?Mission Possible,? attendees from around the world will hear the latest in tunneling and underground construction technology in the two-and-a-half days of technical sessions. The meeting is scheduled for June 24-27 at the JW Marriott Los Angeles Live in Los Angeles, CA. In addition to the technical programming, the accompanying exhibit has attracted 143 exhibitors in 162 booths. And the conference will offer short courses and plenty of social activities that will provide attendees the opportunity to catch up with each other. In addition, a proceedings volume containing all of the 128 papers will be available. An impressive lineup of sponsors will help attendees enjoy the conference. They include Brierley Associates, Kiewit Infrastructure Group, Parsons, Skanska, Traylor Bros., MWH and HNTB.

By David Brown, Adrian St. John, John Comins, Mike King

"INTRODUCTION The Crossrail project provides an East-West link across London enabling an additional 200 million journeys each year linking up major business centres and existing transportation interchanges, while reducing congestion at street level and within the current underground system. The project has built major structures in Sprayed Concrete Linings (SCL), including 5 new stations, 6 crossover caverns and numerous passages, adits and ventilation tunnels. Construction has taken approximately 4 years, and has involved the spraying of over 200,000m3 of concrete. At the start of the project there was a lack of available records from previous projects concerning concrete falls, which hindered risk assessments and the ability to make meaningful comparisons around spraying or material performance. This paper redresses this lack of data by providing information on falls experienced on this project and makes recommendations to assist future projects. Construction Methods Table 1 below summarises the main contracts with elements of permanent SCL. The listed primary lining lengths include pilot tunnels, side drift tunnels and enlargements as separate tunnels.A range of construction sequences were used in order to deal with the design requirements, geometry, and the ground and ground water conditions. The following briefly summarises the build up by layers, with typical design dimensions provided for a platform sized tunnel (approximately 9m internal diameter), excluding tolerance allowances. Some linings were sprayed in more than one layer to allow for inclusion of reinforcement layers or to avoid a too aggressive build-up of thickness: •,Initial shotcrete, or sealing, layer (ISL) of 75mm followed by a Primary Lining (PL) of 300mm. •,Regulating layer of 40mm followed by a Waterproof membrane (Sprayed membrane, 3-6mm). •,Secondary lining (SL) of 250mm with a separate sprayed fire protection layer (FPL) of 50mm."

Jan 1, 2016

By D. Kruse, M. Sanaei

"3D finite element models of the Segmentally Lined Shaft (SLS) structure are simulated as means of numerical analyses of the system’s structural behavior. Top-down constructed rings, comprised of precast concrete segments, create a large diameter, relatively shallow underground space that can be utilized for various applications. To further investigate the effects of soil conditions and different loadings on the shaft structure, the FE model was run under various boundary conditions. Simulations include a) effects of various soil layers on the SLS, including a circumferential boundary of modified ground, b) effects of various soil layers on the SLS without any ground modification, c) Seismic analysis of the SLS with ground modification and d) Seismic analysis of the SLS without any ground modification. Comparing the analyses outcomes emphasizes the significance of the inclusion of the ground modification boundary in the structural performance of the SLS. INTRODUCTION TO SLS Underground structures are classically built rectangular in shape, which normally requires a two-step construction process beginning with installation of temporary shoring to support earth loads during the excavation, followed by the construction of the permanent structure. Attractive and practical alternatives are circular shafts referred to as segmentally lined shafts (SLS). The structure consists of a stacked series of rings formed from an assemblage of precast concrete segments. Top-down constructed systems of large diameter, relatively shallow SLS structures provide both temporary earth support during excavation and permanent structural support for many civil and building applications. The circular shafts sustain the lateral earth pressure mainly through hoop-stress mechanism, resulting in improved stability and structural efficiency. Cylindrical shell structures with large diameter to wall thickness ratios are prone to buckling under external pressure. In typical designs of small diameter shafts and tunnel linings with small diameter to wall thickness ratios, nonlinear buckling analysis (i.e., nonlinear geometric analysis) is usually not considered, since the buckling capacities for those structures are much higher than typical pressures encountered at their design depths. With an economically viable wall thickness, buckling becomes a critical issue, which should be addressed, for circular shafts with very large diameters. In the design and construction of the SLS, the stability of the structure can be improved by modifying the soil surrounding the circumference of the shaft to a limited thickness and to about 10 ft below the finished shaft structure. This thick wall of soil mixed with cement creates a composite integrated structure while serving additional purposes such as ground control and ground water seepage cutoff."

Jan 1, 2016

By R. K. Singhal

A sizable surface mining industry exists in Western Canada. There are the surface coal mines in the provinces of Alberta, British Columbia, and Saskatchewan producing the bulk of Canadian Coal. The two oil sands plants in Fort McMurray, Alberta producing synthetic crude oil are surface mining operations. Much of the metalliferous mining in British Columbia is carried out by open pit methods. This paper discusses the current surface mining methods in both of these industries with particular reference to Alberta. Issues relating to environmental impact assessment, mine reclamation and mine site closure have been dealt with.

Jan 1, 1995

By James F. Archibald, Ferri Hassani, Jacques Nantel, David O. DeGagné

Operators depend upon the success of backfilling programs to ensure that mine activities run continuously (Archibald et al, 1993) where backfilling is an integral part of the mining cycle. In order to ensure that the backfill is prepared and delivered to the stope possessing the required engineering properties, as designed, and that the backfilling process is safe, mine operators at all stages of the backfilling system must be adequately trained for their tasks and be aware of how their work affects other backfilling stages, both up- and down-stream of their station. Mine operator training is primarily based on learning on-the-job from experienced supervisors or training personnel. Classroom training and the availability of reference manuals are less common. While in use by many industries for some time now, computer-based training (CBT) is becoming more readily accepted by the mining industry for a wide variety of training. It is not intended to replace on-the-job training, but to augment it. CBT offers many advantages to enhance operator learning by utilizing multimedia presentations, interactions and on-line testing to teach complex concepts and relationships. Discussions with many operations revealed that there is an industry need for a backfill guide for frontline operator training and as a reference manual for operators and mine engineers. Sponsored by the mining industry and the CIM, "Mine Backfill, An Operator's Guide" has been developed by the Departments of Mining Engineering at Queen's University and McGill University to fulfil this need. "Mine Backfill, An Operator's Guide" is an interactive multimedia package that incorporates high quality colour images, animations, sound, and video with text to review the main backfill methods employed in Canada, including hydraulic/slurry, paste and rock fill. The Guide is divided into training and reference primer sections. When in training mode, the operator is guided through a presentation of common mining and backfill practices and technologies so that he/she may become more familiar with different aspects of backfill processes. To ensure that key concepts have been learned during training, the operator will be tested after each section using a series of multiple choice and true/false questions. When in reference mode, alternatively, the operator may browse through the information in a more detailed and independent fashion through a series of interactive menus. The Guide focuses on the following main topics: resources, surface preparation, distribution, stope activities, health and safety, and quality control. Special features included in the Operator's Guide are a Buyer's Guide, a Trouble Shooting Guide, and an interactive glossary of backfill and mining terms. Concepts in interactive and computer-based learning are also reviewed in this paper.

Jan 1, 2001

By Randall E. Brown

Irrigation simulates a climate change so that crops can be grown that otherwise would not thrive. The abundant sunshine and warm weather of many arid regions induces a rate of growth in excess of that in cooler, moister regions. Hence, the arid part of eastern Washington, traversed by the Columbia River, is admirably suited to irrigation. The Pasco Basin lies in south-central Washington at the south end of the Columbia Basin Irrigation Project of the U.S. Bureau of Reclamation. The Basin, because it lies in the rain shadow of the Cascade Mountains, receives only 6 to 10 inches of precipitation a year with somewhat greater amounts, commonly as snow, on the higher hills. Recent extremes included 3 inches of precipitation from August 1967 to August 1968, and 12 inches in the succeeding "12 months. Most of the precipitation falls during winter. If it were to fall in summer or were evenly distributed throughout the year, evaporation rates probably would produce a true desert.

Jan 1, 1971

By Kadri Dagdelen

New underground coal mines have become increasingly expensive to open. A simple drift mine producing a raw coal product can cost as much as $50 million while a new shaft mine producing a washed coal product can cost up to $200 million. As a result, few if any speculative new mines are constructed. Normally, a long term coal supply agreement is needed to justify new mine projects. Negotiating a supply agreement prior to production start is difficult. Pricing must be based on estimated rather than historic costs and coal quality must be estimated from core hole samples versus actual shipments. Further in todays competitive coal markets, there is little margin for error in either price or quality.

Jan 1, 1983

By T. Matthews

"One critical factor in mineral reserves reporting, as well as mine-reserves reconciliation, is the impact of dilution and ore loss in the mining process. This paper considers the implications of various factors on dilution and ore loss projections, by orebody geometry, mining method, and ore control systems. We also discuss the implications of resource estimation methodology on dilution for reserves. DEFINITIONS Dilution and ore loss are two critical concepts in mining, which address the differences encountered between modeled grade and tonnages and actual production. Dilution is volume increase and grade reduction caused by multiple factors, chief among which are mining of waste material along ore-waste contacts, mining of internal waste as ore, and misclassification of waste as ore in the ore control process. There are also geostatistical and estimation aspects sometimes lumped with dilution, including the volume-variance effect (the tendency for small volumes of material to include a less regular distribution of grade than large volumes of material). Ore loss is described as reductions of ore volumes in the mining process due to misclassification of ore as waste in the ore control process, exclusion of discontinuous mineralization from mining due to geometry or continuity, and mechanical losses in the mining process. Dilution is typically taken as an increase in tonnes of ore with no change in contained metal (and thus results in a reduction in grade.) (Some workers consider the likely grade of the diluting material as well, particularly in deposits with gradational grade boundaries—this will be addressed later in the text.) Ore loss is typically taken as a reduction in tonnes at average grade of the ore, and thus results in a reduction in both tonnes and contained metal. If model (resource) tonnes are Mt, grade is Mg, and contained metal is Mm, the resource with ore loss (L) and dilution (D) included (Rt, Rg, and Rm) will be:"

Jan 1, 2015

By Nellie E. Guernsey, Louis J. Sousa, Alfred Weiss, Nickolas J. Themelis

Over the past decade, numerous factors have led US copper firms to face increasingly severe competition from low cost foreign producers. As a result, greater attention is being devoted to developing and implementing new technology that can reduce costs and maintain the competitive position of domestic firms while simultaneously meeting environmental requirements. To obtain a better understanding of the likelihood of the development, adoption, and use of innovative copper technologies in the future, the Bureau of Mines contracted with Mineral Systems Inc. of Stamford, CT, to undertake a systematic survey of technological experts in industry, government, and the academic community. According to the survey, major developments in exploration over the next 25 years are likely to be in technologies that facilitate analysis and interpretation of deposit data rather than those that enable the collection of additional data. Most new copper mining and beneficiation technologies are likely to represent evolutionary extensions of existing systems with a notable increase expected in the application of information systems technologies and computer control methods. A possible movement towards increased usage of continuous mining systems in copper was also noted. Experts indicated that several copper smelters are under consideration for extensive renovation and, as a result, flash smelting technology is expected to become much more widely used in the US. A gradual movement toward continuous smelting methods was also forecast. In copper refining, the major technological change expected is the gradual automation of various refinery operations. Finally, though increased usage is expected, in situ solution mining and hydrometallurgical processing of sulfide ores are not expected to become widespread over the forecast time horizon. This first article in a two-part series describes the survey method chosen and the technological innovations selected for eval¬uation. Also discussed are the assessment panels, background scenarios, critical events, and diffusion forecasts. Next month, part two will address technology forecasts resulting from the study. Featured are discussions on future copper exploration, mining, beneficiation, smelting, refining, and recycling. A cost/benefit analysis will also be included. Methodology Selection of Assessment Method To develop a consensus forecast of technological change in the copper industry, a technique for systematically polling subjective opinions of experts was required. After conducting a literature survey and some preliminary testing, the direct probability assessment method was selected. With this assessment method experts are asked to express in quantitative terms their judgment of the probability that a specified event will occur, usually over a series of time frames. The method was chosen because the experts were observed to be more comfortable with this approach during the testing period, and the results of this process effectively satisfied the assessment objective. The experts generally could provide more precise estimates of the timing of future events using this technique because it was the least cumbersome of the assessment methods tested. Identification, Selection, and Description of the Technologies The initial list (Table 1) of innovative copper technologies assessed in the study was developed from two principal sources: knowledge and expertise of the study team and a review of relevant technical literature. From this list of 47 potential technologies, 10 were selected for detailed assessment. Table 2 lists 35 technologies that were subsequently identified in the first series of assessments. Twelve technologies from this list were also selected for detailed evaluation in a second assessment round. Criteria used for the final selection of technologies for detailed assessment specified that: • The expected impact of each technology on copper supply (i.e.,

Jan 9, 1983

By J. A. Chermak, D. D. Runnells

Sulfide-bearing waste rock, ore and tailings have the potential for generating acid rock drainage (ARD) when exposed to an oxidizing environment. The possibility exists of utilizing the acid produced to react with lime and/or limestone to form a self-sealing cap on the reactive waste rock and tailings. Laboratory column experiments were conducted using acid-generating waste rock with a surface amendment of limestone and/or lime. Artificial rainwater was introduced and allowed to drain through the columns. Results demonstrated that the limestone and lime reacted with the acidic rock, resulting in the precipitation of a hardpan layer of gypsum and amorphous iron oxyhydroxide at the surface. The hardpan layer significantly reduced the effective permeability of the column. Based on the results of this study, it should be possible to create hardpan layers as chemical caps to significantly reduce the infiltration of rainwater and snowmelt into acidic waste rock or tailings material in the field. Unlike traditional capping methods, e.g., clay and high-density polyethylene (HDPE) covers, chemical caps should be self-healing.

Jan 1, 1998

By Clete Stephan, John Urosek, Ian Anderson

The Endeavour Colliery is operated by Powercoal Pty Ltd. It is located in the Central Coast of New South Wales, Australia. The mine has been in operation for about 30 years, producing around 600,000 tons of export coal annually from two production sections. On June 28. 1995, an explosion occurred underground in the 300 Panel at approximately 9:50 a.m.. There were thirty miners underground at the time of the explosion, all of whom were safely evacuated. From June 29 through July 10, personnel did not enter the mine. However, gas samples of the mine atmosphere were obtained from underground monitoring stations and analyzed. Samples were also obtained from boreholes that were drilled from an adjacent mine. On July 10, the atmosphere at the underground monitoring locations and at the boreholes appeared stable with minimal risk of combustion occurring underground. Plans were developed to begin the recovery of the underground workings. The recovery of the underground workings was completed on July 13. The underground investigation of the explosion began on July 14. The investigation was conducted by the New South Wales Department of Mineral Resources. Technical assistance was pro- vided by the United States Department of Labor's Mine Safety and Health Administration (MSHA).

Jan 1, 1997

By Victor F. Hollister

This section includes examples of discoveries of Kuroko- and Anyoz-type massive sulfides, and shale-hosted, zinc-lead deposits, and describes exploration models for each group of case histories. Exploration or empirical models can differ from genetic models, because ore guides and controls are emphasized in exploration models. Genetic models may form the scientific basis for exploration or prospecting models, although factors that are important to the localization of ore are stressed in exploration models. The paper by Sato (abstracted herein) on Kuroko deposits can be used as a general exploration guide for that type of deposit. It is clear, however, that no unambiguous stratigraphic control for Kuroko-type ore is given in the Sato paper. The paper by MacIntyre (an excerpt herein) describing Gataga, Midway, and Windy Craggy includes most of the elements of the shale-hosted and Anyox models. Although more recent work by the Geological Survey of Canada has modified the Windy Craggy stratigraphy, the Anyox model as applied to Windy Craggy is well described in the MacIntyre (1983) paper. Discoveries of ophiolite-, Ducktown-, volcanic-associated Ni- Cu-, and Besshi-type deposits are not included in this section. Conformable massive sulfide deposits are generally assumed to be syngenetic. Sulfides in the crosscutting feeder zones, however, are classed as epigenetic. Therefore, volcanogenic massive sulfides can contain both a syngenetic and an epigenetic component. Vital to the development of the epigenetic component is a heat source that propels the convection cycle that forms both components. In all massive sulfide discoveries described in this section, it is assumed that a volcanic magma fueled the hydrothermal fluids.

Jan 1, 1991

By W. J. Halvorsen

Means for minimizing the disadvantages of thermal drying are suggested. The other ap¬proach of substituting other techniques in place of thermal drying is also discussed. Recent devel¬opments in fine coal screening dry down to 3.2 mm (0.125 in.) and 2.0 mm (10 mesh) offer an econom¬ical means in certain cases.

Jan 1, 1988

By William E. Little, William R. Sharp, Edward R. Kennedy

Cost o f mechanical tunneling requires the knowledge of many machine/rock parameters such as rock types, machine power, penetration rate, cutter life, maintenance schedule, etc. Capital investment, labor requirements, and project scheduling will all play an important role in defining the economics of the overall project. Knowledge of the cost sensitivity of different project parameters will improve the overall success of any particular tunneling project if this information is incorporated into an effective management plan. Through the use of an interactive graphic computer program written for a microcomputer, one has the ability to quickly evaluate relative costs for a variety of parameters for either an existing project or for a proposed site.

Jan 1, 1983

By Daniel J. Brunner

The U. S. Department of Energy (D.O.E.) requires that the prospective nuclear waste repository in Basalt at Hanford, Washington, comply with State of California mine and tunnel safety orders. These regulations require that all main fans be installed in such a manner as to permit prompt reversal of airflow. This paper evaluates the requirement of air reversal and the appropriateness of imposing such regulations on the proposed nuclear waste repository in Basalt.

Jan 1, 1988

By H. G. Fleshman

?Wyoming bentonite? has become almost a world-wide trade mark for high quality sodium bentonite. Although bentonite is produced in more than a dozen U.S. states the largest producing area covers Wyoming and adjacent parts of Montana and South Dakota. Bentonite was originally known as Taylorite and later renamed Bentonite by Dr. Sam Knight, the State Geologist of Wyoming. The new name came from the Fort Benton shale member of the Mowry Formation. Bentonite is a clay consisting essentially of the montmorillonite group of minerals. Since bentonite has good ion exchange capabilities, various cat-ions are easily replaced. These cations are usually calcium and sodium; however, magnesium, lithium, potassium, and others can be exchanged. One way of classifying the clay is based on its swelling capacities when wet or added to water. Bentonite having sodium as the dominant exchangeable ion typically has very high swelling capacities and forms gel-like masses when added to water. Bentonite in which exchangeable calcium is more abundant than other ions has much lower swelling properties than sodium varieties.

Jan 1, 1987

By C. C. Bailie

This paper will be concerned with those mineable coal measures at depths necessitating deep mine operations in the range of 200 feet to 800 feet in depth. The area is generally classified as the Southern Illinois Field but more specifically includes that part of the state south of a line extending from St. Louis, Missouri on the west to Vincennes, Indiana, on the east. This embraces an area which presently includes a total of 38 shipping mines and 5 local or truck mines. Of these shipping mines, 22 are deep (shaft or slope) mines and the remaining 16 are strips. The average annual production of the shipping mines is around 29 million tons. The presently classified mineable reserves of the area are estimated at around 70 billion tons.

Jan 1, 1964