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By Philip Antunes, A. E. (Tony) Reschke

"INTRODUCTION Tunnel Boring Machine (TBM) operations require the injection of material into the annular tail voids as the machine advances ahead of the segmental concrete lining. This annular gap is created because the cutting diameter of the TBM has to be larger than the outer diameter of the concrete segments of the tunnel lining. Fundamentally, the two basic types of annular grout are thick, concrete like mortars and thin, mobile, two-component grouts. While some European countries seem to still favor the concrete like mortars, from a global perspective it is now the two-component type grouts that dominate the industry. Two-component type grouts are comprised of an “A” component grout (typically cement, flyash, bentonite and a retarder/stabilizer) and a “B” component accelerator (sodium silicate or water glass as it is sometimes known). They are thus sometimes referred to as A/B type or bi-component grouts and were pioneered by the Japanese over 30 years ago. They offer a host of operational benefits over thick mortars, such as reduced settlement (Feddema et. al., 2001), effective penetration of the void space, with less energy, and reduced strain on the segmented linings (Robinson et. al., 2007). Two-component grouts are highly mobile and can be pumped many kilometers. The use of a retarder/stabilizer can also extend the shelf life of the “A” component grout for several days while the early strength of the accelerated grout stabilizes the ground and supports the segmental liner almost immediately. The batch plants that prepare the two-component grouts use one of two possible mixing methods for preparing the “A” component grout. The simplest plants use paddle type mixers and numerous tunnels worldwide have been successfully grouted using this technology. However, a superior type of mixer is available, namely the high shear colloidal mixer. Keller Colcrete successfully pioneered the development of the colloidal mixer back in 1937 and for over 75 years colloidal mixers have been internationally recognised as the most efficient method of mixing cement based grouts (Houlsby, 1990). These mixers are used in grout preparation for radioactive waste encapsulation, hydro dam grout curtains, soilcrete jet grouting, soil nailing, and numerous other geotechnical applications. In tunnelling, these mixers are also used for ground treatment, compensation grouting and for the preparation of bentonite lubrication for pipejacking. It has been only within the last decade however that these high-shear colloidal mixers have been adapted for use in the preparation of two-component grouts."

Jan 1, 2016

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

The Mount Royal Tunnel (MRT) is a 100-year-old railway tunnel located in Montreal, Canada. The tunnel is approximately 5 km long, 8.7 m wide and 5.5 m high, with a constant 0.6% grade. This existing tunnel will be used by the new Montreal light rail transit network, Réseau Express Métropolitain (REM). This requires the tunnel to be inspected, rehabilitated and made compliant to the recent safety standards. This paper presents the details of the structural inspection and rehabilitation of the tunnel along with the repair methods, addition of a center wall as well as the enlargement of the tunnel section.

Jun 13, 2021

By Karoly C. Kocsis, Kyle A. Scalise, Marcelo Bandeira Teixeira

Understanding the effects of various ventilation and climatic parameters on the work conditions and comfort in underground mines is critical for efficient ventilation system design and cost savings and to ensure the health and safety of mine workers. To understand the effects that the thermal damping effect (TDE) and the thermal flywheel effect (TFE) have on the ventilation system design and potential cooling system, this paper compares and analyzes the wet and dry-bulb temperatures at the bottom of an intake shaft using two modeling software packages, Ventsim™ and Climsim™. The comparison shows the consequences and importance of taking into account the TDE/TFE when predicting the climatic conditions in future underground mines, especially when deciding on whether a cooling system should be employed in order to provide adequate climatic conditions in the production stopes, dead-end development headings, and throughout the mine. Ventsim™is able to account for the TFE, while Climsim™does not. Both software packages have their uses and are used within the mining industry, but it is useful to understand their limitations and where the future of underground climatic modeling will lead.

Oct 9, 2020

By J. Kretschmann, P. Goerke-Mallet, C. Melchers

Mining always leaves a mark behind. Dealing with this legacy is not only a tremendous challenge in Germany, but internationally too. The Technical University Georg Agricola (THGA) in Bochum, Germany, has established a Research Center for Post-Mining. Researchers combine expertise from a variety of technical and nontechnical fields in their quest to shape the post-mining era that completes the mine life cycle. In this respect, the Research Center focuses on four research areas: Perpetual tasks and mine water management, Geomonitoring, Material sciences and site transition. With more than 200 years of successful partnership with the mining industry in Germany and abroad, THGA offers a perfect setting for fresh and sound ideas in order support mining’s social license to operate. The aim of the paper is to describe the Post-Mining Research Center along with exemplary research projects that are of interest to the mining industry globally and to foster technical communication and research networking.

Mar 2, 2022

By D. T. Iseley, A. L. Atta-alla

INTRODUCTION The extension project of the East Line Subway of Atlanta's subway network includes the construction of two single track transit tunnels under Interstate Highway 285. The project will be in DeKalb County, Georgia. The length, width, and height of each tunnel are 54.25, 6.3, and 7.2 m (178, 21, and 23 ft) respectively. The ground cover above the tunnel crown ranges from 1.5 to 3.25 m (5 to 11 ft). A soil pillar about 5.5 m (18 ft) wide will remain between the tunnels. The construction of each tunnel includes (i) installation of 21 steel soil support pipes of 75 cm (30 in) diameter, (ii) jet grouting 15 soil cement shafts of 60 cm (24 in) diameter in the soil under the pipes, (iii) contact grouting behind the tunnel lining and between soil support pipes and pavement, (iv) excavation of soil inside the soil support arch, and (v) installation of steel pile foundation, steel sets, and permanent tunnel lining of cast-in-place concrete, all as shown on the cross section in Fig. 1. The soil profile can be described from top to bottom as cement/asphalt concrete pavement, a fill layer consisting mostly of stiff sandy silt/firm silty sand, a residual soil layer consisting mostly of silty sand/sandy silt, partially weathered rock, and solid rock.

Jan 1, 1991

By V. Svalbonas

With the occurrences of serious mill structural failures on both ball and primary mills, the mining industry has entered the era of detailed fabrication specifications. Such specifications, however, have been developed as individual entities, often by people not related to the mill design function. Therefore, there has been no effort to relate mill failure or safety to the existence or elimination of specific fabrication flaws; that is, no cause-effect failure relationships have been developed. The omission of this step produces a specification which can be termed uneconomical at best. The present paper attempts to fill this void, by reviewing methods for design consideration of flawed structures, and describing experimental tests used to tie such data to a meaningful quality assurance program in fabrication.

Jan 1, 1985

By Thomas G. Langton

The demand for mineral raw materials, especially in the major industrialized nations, has grown rapidly during the past three decades. One consequence of this growth has been an increasing reliance by the large industrialized countries upon nondomestic mineral supplies. These mineral supplies, to a large extent, have been developed by capital from the major industrialized countries. Until recently, most foreign mining ventures were either wholly-owned subsidiaries or joint ventures between two or more mining companies. The recent rise of economic nationalism has substantially changed the business climate and parameters under which foreign investors operate. This paper describes some of the underlying reasons for this change and notes how investors have adapted to the new business conditions.

Jan 1, 1974

By James P. Connell

The Montana Operations of the Anaconda Company constitute an integrated, though geographically separated, non-ferrous metal production complex. The mines are located at Butte and consist of one large open-pit mine, two small underground mines, a precipitation plant for both underground and pit-dump leach water, and the Weed Copper Concentrator. The smelter, located at Anaconda, Montana 25 miles to the west, processes all Butte copper shipments as well as copper materials from both Anaconda and private mines. Copper and zinc are refined at Great Falls, Montana, 165 miles to the north. Other facilities developed over the years include the Anaconda Forest Products Division, the Butte, Anaconda, and Little. Chicago Water Companies, and the Montana Hardware Company. Data processing for these operations has been performed on an IBM 360 Series, Model 30 computer, utilizing a Disc Operating System. This was replaced in September 1970 with a 360 Series, Model 40 128K unit. In addition, some data processing is also done for Anaconda Company operations located at Britannia Beach, British Columbia; Columbia Falls, Montana; Yerington, Nevada; and Twin Buttes and Tuscon, Arizona. The material under discussion in this paper will be concerned primarily with the mining operations at Butte.

Jan 1, 1970

By Dermot M. Ross-Brown

The more important factors controlling the design of pit slopes are related to the local geology over which the designer has little or no control. Nevertheless, there are some factors over which the designer does exert some control and these concern the say in which the rock is excavated and supported. They include blasting, face cleaning, water control, and the use of rock improvement techniques. The paper discusses these factors and relates the extra costs incurred to the steeper slope angles that can usually be obtained. It is demonstrated that even a modest increase in bench angle of 5° through improved excavation techniques can pay off in a single push-back.

Jan 1, 1975

By Q. Feng

"Efforts have been tried to apply the mixture of mine tailings and fly ash as construction materials. Through the present investigation, a protocol to make construction materials using the mixture of mine tailings and fly ash has been set up. The experiment results of the present work also help set up the working conditions such as activation temperature and time, the concentration of NaOH, the addition of Ca(OH)2, forming pressure, mine tailing to fly ash weight ratio, curing temperature and curing time. The findings of the present work provide a novel method for the geopolymerization of the mixture of mine tailings and fly ash as construction materials, such as bricks for construction and road pavement. INTRODUCTION In mining activity, after the valuable materials are extracted from ores, millions of tons of solid rejects, i.e., mine tailings, are stored in the tailings dam, which occupies a huge area of land and leads to high monetary, environmental and ecological costs. For example, the impoundment of mine tailings can bring with serious environmental problems such as mine dust and tailing dam failure. On the other hand, the making of general construction material results in a lot of greenhouse gas emission. Therefore, it is of great interest to utilize mine tailings, for which a lot of energy has been consumed during the comminution process, as construction materials using the novel geopolymerization technique. (Xu and van Deventer, 2000, 2002a, 2002b; Pacheco-Torgal et al., 2007, 2008; Zhang et al., 2011; Ahmari et al., 2012) Fly ash is another industrial waste which needs to be carefully impounded because of its potential impact on environment. Many efforts have been tried to utilize fly ash as construction materials because it is a silica/alumina rich aluminosilicate source. In addition, the facts that fly ash is quite reactive to alkali and its particle size is usually very small (< 50 microns) make the specific material an ideal source for the geopolymerization process to make construction materials. Geopolymerization is a process of obtaining a polymeric structure from aluminosilicate by dissolving aluminosilicate sources in a strong alkali (NaOH) solution at an elevated temperature. After being cured at an elevated temperature for a specific time, the geopolymerization product shows a greatly increased compressive strength. Therefore, the product can be used as construction material such as bricks and road pavement. It provides a very promising method to apply aluminosilicate sources such as mine tailings and fly ash as construction materials."

Jan 1, 2016

By Robin P. Gardner

The mechanistic approach to comminution consisting of incorporating particulate breakage functions into a suitable population balance equation has been developed by a number of researchers over the past decade or so. (1) To date this approach has been developed and demonstrated primarily for batch-operated, laboratory or small-scale ball mills. However, since industrial mills are mostly quite large and operated in the continuous mode; suitable population balance models and methods for obtaining the necessary breakage and other model parameters must be developed. This paper describes and investigates a radioisotope tracer technique for this purpose, Population balance models previously developed(2,3) are adapted for this study.

Jan 1, 1974

By Sandeep Upadhya, Marc Morgan, Baljinder Bassi, James Fletcher, Mike Deevy, Nishant Nayan

"In order to protect public safety in the event of a deliberate fire attack, underground rail authorities are increasingly considering the need to design for arson-initiated fire scenarios. Where typical design fires for modern rolling stock mean a peak fire size is reached after 12 minutes, an arson-initiated fire reaches its peak within 2-3 minutes. We present the innovations required to successfully incorporate this requirement on a recent design-build project. In stations 3D modelling is used to optimise smoke reservoir designs, smoke chimneys, station boxes and tunnel geometry to allow coordination with structural requirements. In tunnels, novel coupling of one dimensional network modelling and 3D Computational Fluid Dynamics (CFD) is used to improve assessment of complex fire scenarios. Finally, the impact on tunnel structures is assessed through comparison with standard time-temperature curves and risk of explosive spalling. INTRODUCTION An increasing regulatory environment and the appreciable influence that terrorist incidents have had on public safety policy have motivated the need to protect against large arson fires, especially in civil structures and public transport systems. With a greater reliance of a growing urban population on underground subway systems, design of such infrastructure is continually being reassessed and developed worldwide. Underground rail authorities are paying increased consideration to the design of fires - with properties beyond the upper regions of growth and intensity - amongst arson fire studies. Use of fire hardened materials on modern rolling stock means fires caused accidentally can be expected to develop relative slowly. However, recent experiments involving large initiating fires (as would result from an arson attack) have shown rapid fire growth rates and flashover leading to greater maximum heat release rates, Hadjisophocleous (2012), White (2010), and Lönnermark, et al. (2015). This paper describes the challenges and innovations required to complete a detailed design to control smoke from such aggressive super-fast growing fires. Computational modelling is used to demonstrate the required smoke control design by configuring the mechanical exhaust system combined with careful coordination with the architectural and structural design. The design objectives are to provide tenable egress paths in accordance with NFPA 130 (2014) and fire-fighting access. Finally, analysis of the design fire is used to inform the tunnel lining design, reducing the risk of explosive spalling, protecting the asset in the event of a severe fire."

Jan 1, 2016

By Michael J. Humenick

A laboratory experimental research project was conducted to evaluate the use of chlorine for the oxidative destruction of residual ammonia which may remain in ground water after in-situ uranium solution mining operations. The work tested the idea of the injection of high strength calcium hypochlorite solution into the mining zone to convert ammonia to nitrogen gas as a final clean-up process for ammonia removal from the ground water system. The paper details ammonia removal efficiency as a function of chlorine dose, reactant and product material balances, and how the concept may be used as a final ground water restoration process.

Jan 1, 1982

By Ernest L. Ohie

In 1939 the Geological Society of America published a summary of the geology of the ore deposits of the Mississippi Valley region, This volume, edited by E. S. Bastin, contained contributions from the foremost students of the area which described theregionalgeologic setting of the various deposits as wel as the detailed geology as then known. The various ideas as to the origin of the ores were discussed with the general, though not unanimous, conclusion that the deposits were hydrothermal products, Only those deposits in the immediate Mississippi Valley area were considered without any attempt to introduce evidence from other districts generally accepted as being of the "Mississippi Valley type." Since 1939, much new information has come from extended studies of two of the important districts described in the 1939 report andimportant extensions of the known ore have been found. Likewise, concentrated geologic efforts have been fruitful in severa "Mississippi Valley type" districts - both U. S. andforeign - not treated in the 939 paper. The wealth of new field information on the structural and stratigraphic relations of this interesting ore type, coupled with the results of theoretical and laboratory studies of the past 18 years, makes desirable a review of our present knowledge and interpretation of these important deposits which for many years have yielded over 20 percent of the world&apos;s annual production of lead and zinc, together with large amounts of fluorspar and barite. No restatement of the details of the geologic evidence willbe attempted here; the interested student is referred to the papers cited. Slide No. 1 shows the distribution around the world of the deposits under consideration. A principal thesis of my remarks is that there is so much similarity in all these deposits that it seems necessary for all of them to have had a similar mode of origin, whatever that may be. Variations in the shape, size and mineralogy of the orebodies give each district some individuality, but there are enough of the "typical" characteristics present in all cases to make classification in the "Mississippi Valley type" agreeableto most geologists. Thus the overall process giving rise to the ore solutions surely was the same for all in the group. Either they all have igneous affiliations or they all do not. Acknowledgment of this kinship between deposits in the various districts offers many advantages in trying to arrive at a decision as to just what the origin may have been, for the amount of guiding and limiting evidence which must fit into the hypothesis is greatly increased over that available in any one district, To a certain extent this was recognized by the authors of Special Paper 24 in treating all of the immediate Mississippi Valley areas together; by expanding the consideration to include ore deposits of this type all over the world the changes of success, i.e., arriving at the correct answer, are improved several fold. Since most of these districts are quite simple structurally, a number of hypotheses might fit the facts in any one of them, but if the facts to be met can safely be drawn from all the districts, then the explanations which will fit all the data are much less numerous. One purpose of this paper is to call attention to the field facts that have been reported from the .various areas which seem to have an important bearing on the kind of ore fluid that was responsible for the ore and on the way it circulated.

Jan 1, 1958

The Xinglongzhuang Coal preparation plant project was a joint effort by American and Chinese engineers and for the most part designed to American standards. The plant owner and operator is the Yanzhou Coal Mine Administration, a division of the Shandong Coal Corporation. These are state owned companies which ultimately fall under the Ministry of Coal in Beijing. The new 3.0 million ton per year Xinglongzhuang mine is located in southern Shandong province in east-central China about mid-way between Beijing and Shanghai. This is an agriculture area, flat terrain, relatively dry climate with temperatures similar to Western Kentucky. During Confucius time (551-479 B.C.) this area was known as the state of Lu. Confucius home town of Qufu is about 20 kilometers to the north-east of the mine site.

Jan 1, 1989

By Amin Mousavi, Soroush Khazaei, Yashar Pourrhimian

As a factory-like method, sublevel caving consists of development activities, stockpiling and production activities that are carried out on different levels independently. Therefore, considering the operation from the development phase to the plant will lead to more reliable production scheduling. This paper presents a mixed integer linear programming framework for the long-term production scheduling of sublevel caving that maximizes the net present value while satisfying development activities, mining, and processing capacities, continuous mining, the allowable number of active mining units, grade blending, and vertical and horizontal sequencing. The model is coded in Jupyter Notebook and is solved using the CPLEX solver.

Jun 25, 2023

By Wilbur I. Duvall

INTRODUCTION This chapter outlines some general principles and procedures that a rock mechanics engineer can use to arrive at a logical design for the size, shape, and spacings of underground openings in various types of com¬petent rock formations. Rock formations can be clas¬sified into six major categories which are useful for design purposes, provided the necessary input data are available regarding the geology of the site, the physical properties of the rock, the in-situ stress field in the rock, and the general geometry of the underground openings. The US Bureau of Mines (USBM) developed a rock classification system based upon these concepts and found it to be useful for design purposes (Obert, et al., 1960; Obert and Duvall, 1967). This classification sys¬tem is given in Table 1; however, an extra column has been added to the original classification to indicate the appropriate design techniques for each rock class. In this classification system, two main classes of rock are considered: competent rock and incompetent rock. Competent Rock Competent rock is any rock which, because of its mechanical and geological characteristics, is capable of sustaining underground openings without the aid of any structural support except that provided by unmined rock in the form of pillars and side walls, etc. Roof bolts and small random props which support only local loose rock are not considered structural supports. Competent rock is further subdivided into three ad¬ditional categories-massive, laminated, and jointed¬ which are defined as follows: Massive Rock: Massive rock is a rock formation where the spacing between mechanical defects such as joints, partings, or faults is equal to or greater than the critical dimensions of openings, or where the strength of the bond across these mechanical defects is com¬parable to the rock strength. Laminated Rock: Laminated rock is a rock forma¬tion divided by approximately parallel planes of weak¬ness into lamina whose thicknesses are small compared to critical dimensions of openings and where the bond between the lamina is weak compared to the rock strength. Elastic Rock-This is rock whose physical proper¬ties will permit the use of elastic theory to predict strains and displacements from applied stresses. Inelastic Rock-This is rock whose physical proper¬ties are such that strains and displacements are a strong function of time as well as applied stress. Incompetent Rock Incompetent rock is any rock which, because of its mechanical and geologic characteristics, is not capable of sustaining underground openings without the aid of additional structural support in the form of linings, steel sets, or systems of props. This classification system for rock depends not only on the mechanical and geologic characteristics of the rock but on the size of openings and their depth be¬low the surface. For example, many competent rocks at shallow depths for small stress fields could become inelastic rock at greater depths and larger stress fields, or competent massive rock for small openings could be¬come laminated or jointed rock for larger openings. Thus, to classify rock for design purposes requires a knowledge of the geologic properties of the rock mass, the physical properties of the rock, the general size of the openings to be mined, and the average range of the in-situ stress field to be encountered. To design underground openings and structures in rock, it is necessary to use criteria of failure for rock under various stress conditions, and to use safety factors to allow for differences between laboratory and in-situ strength properties of rock and to account for errors in¬troduced by the various assumptions made in the design process. Criteria of failure based on maximum stresses have been found to give reliable results in practice. Thus, it is assumed that rock will fail in tension when the tensile stress exceeds the tensile strength of the rock as determined by a standard modulus of rupture test on samples of rock core. If the tensile stresses in rock are small, then it is assumed that the rock will fail at a value of compressive stress equal to the compressive strength of the rock as determined by standard uniaxial compres¬sive strength tests on samples of rock core. These fail¬ure criteria, when used with appropriate safety factors, can be expressed as:

Jan 1, 1982

By H. C. Juvkam-Weld

R. Michael Craig Mr. Juvkam-Wold&apos;s article is a timely and much needed presentation of the method of depressurization to reduce ground-water inflow into mine shafts. The article is very informative and discusses the effects of depressurization upon shaft inflows adequately. However, the article omits a discussion of another important benefit of depressurization: the reduction of potential for artesian burst or, as it is also called, floor heave. Confined aquifer systems (artesian aquifers) can contain water under several hunder pounds per square inch (psi) of pressure. For example, water levels at elevations of 455 m (1500 ft) or more above the top of the Westwater Canyon member of Reply by H.C. Juvkam-Wold In general, Mr. Craig&apos;s comments are useful and accurate regarding the potential benefits of aquifer depressurization. However, two of his points require further explanation since they may lead to a misunderstanding of my paper and its predictions. These refer to his comments regarding failure to account for storativity and to non-artesian conditions. Equation 5 is indeed Darcy&apos;s steady state equation. However, as a careful review of the appendix in this paper will reveal, I have used this equation to represent semi-steady state conditions. In other words, steady state conditions are assumed at any instant of time, but conditions may change gradually from

Jan 2, 1983

By L. J. Nicks

The current U.S. Bureau of Mines research program is addressing the recovery of flake graphite from kish, a steelmaking waste product, and the use of zeolites from abundant domestic natural deposits for efficiently cleaning up mining industry wastewater. The United States is almost totally dependent on imports for its graphite needs, but this may change depending upon the results from a pilot plant being constructed by industry using Bureau technology. Standard mineral processing techniques were applied by the Bureau to recover high-quality flake graphite from kish. It was considered innovative enough to receive an R&D 100 Award in 1992, and its commercialization has the potential to supply the total U.S. demands for graphite many times over. Zeolites have ion exchange properties similar to ion exchange resins, but are less expensive and available in large quantities. Samples of naturally occurring zeolites were tested for their efficiency in removing metal ions from synthetic and industrial waste solutions. The tests focused on defining their selecting, loading, eluting, and regenerating characteristics, and on developing a method for recovering the metal ions as added value products. The results showed that the removal of metal ions with zeolites from acid rock drainage (ARD) solutions is technically feasible and that this technique has the potential for being used in an integrated chemical treatment systems approach either as a primary or secondary cleaning step.

Jan 1, 1995

By Kathleen A. Altman

INTRODUCTION The basic premise of the ideas presented in this paper are as follows: Engineers believe that "theoretically" it will work. Operators ask what they must do to make it work. And, people can screw it up. r Today the challenges conf onted during the engineering, startup and operation of mines are becoming more complex. As mining and processing professionals, we are called upon to trav­el all over the world, are subjected to a wide variety of climates and must deal with a numerous cultures and people. Historically, for the majority of the people working in the mining industry, the primary challenges related to projects have focused on the differing perspectives of the disciplines involved. For example, geologists focus on resources and reserves, mining engineers relate to tons or tonnes, metallurgists count ounces or pounds or kilograms of product, mechanics emphasize availabil­ity, human resources personnel deal with absentee rates and turnover and accountants watch the bottom line ($$'s). As the world has become "smaller" and the mining industry has become more globalized, the puzzle is becoming increasingly difficult. Even the most experienced in the crowd of mining profes­sionals are oftentimes surprised by the types of problems that are encountered. Try as we may, we cannot anticipate the complex­ity of dealing with the human side of an operation.

Jan 1, 1998