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By Paul A. Roy

The North Shore Connector Project for the Port Authority of Allegheny County constructs twin Tunnel Boring Machine (TBM) tunnels through cohesive soils and rock beneath the Allegheny River and a narrow city street in Pittsburgh, PA. The tunnel alignment includes an historic building on shallow foundations, modern buildings on deep foundations, and an office building constructed directly over the alignment during the design of the tunnel sections. This paper provides an overview and update of the general site conditions, TBM tunnel design, and support of excavation for the TBM launching pit. Deformation limits, ground improvement, monitoring and mitigation plans are also discussed.

Jan 1, 2008

By Z. Sun

Magnetic fields have been used for inclusions removal from melt and preparation of materials with gradient compositions. Fundamental in these applications is that the induced magnetic forces on the particles/melt can enhance migration and change the interaction behavior. In the present paper, migration and interaction behavior of electrical-insulating particles in a conductive melt under strong magnetic field are theoretically analyzed. It is found that the migration can be considerably enhanced for micrometer sized particles by applying a strong magnetic field. In addition, two forces are involved in the interaction between two particles: the interparticle magnetic dipole-dipole attractive force due to magnetization and the repulsive force induced by flow of the melt. This theoretical analysis renders a better understanding of recent experimental results. Additionally, a new method by using strong magnetic field can be proposed to control the particle size distribution for the preparation of metal-matrix composites.

Jan 1, 2009

By P. N. Saavedra, E. A. Salamanca

"The maintenance strategies in the mining industry are changing from operative and periodic inspection strategies to a condition-based, predictive maintenance strategy centred in vibration analysis plus complementary techniques. Condition monitoring can also help to improve availability by being able to pinpoint and diagnose problems on operating machinery at an early stage. This reduces unscheduled downtime and production losses.However, in mining, for shovels operating in transient modes, with variable load and/or speed, the FFT (Fast Fourier Transform) standard approach is not directly applicable for analysis. This work illustrates how spectral order analysis and new transforms, called time-frequency transforms (TFT), allow us to monitor the shovel when it is working. Some practical examples showing the application of these analysis techniques to occasional vibrations measured on hoist and crowd transmission of a shovel are also presented. It is shown that at present, it is possible to carry out the vibration monitoring in the mining shovel while it is working, therefore avoiding the high cost of a loss of production which can occurr in traditional monitoring, where the measurement is taken while the shovel is out of production."

Jan 1, 2002

By Dziurzyn&apos, W. ski

This article outlines the results of a computer simulation reproducing the transport of a mixture of air and methane following the outburst on 25 November, 2005 in transport gallery D-6, bed 409/4, at the ?Zofiówka? hard coal mine. Based on a mathematical model, numerical method and boundary conditions from the disturbance caused by the outburst, the Ventgraph system of computer simulation programs was adopted for the study. We performed a computer simulation of the influence exerted by the outburst on the propagation of the air and methane mixture, and compared the results of this simulation with those of the actual event as registered by sensors of the mine monitoring system. A validation of the model allowed us to present temporal changes in the concentration of methane and air along flow routes. Keywords: mine ventilation, outburst of methane, numerical simulation, monitoring system.

Jan 1, 2008

By Stacy Loizeaux

The Beirut Hilton Hotel, which was built in 1975, but never occupied, was imploded on Sunday, July 14, 2002 by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland and their client, Optimal Engineering Consulting & Contracting, SARL, (OECC) of Antelias, Lebanon to make room for a new hotel. Twenty-seven years ago, just days before the grand opening, the Hilton Hotel became the site of fighting in Lebanon’s Civil War. Christian and Muslim militiamen fought room to room for control of the building and other nearby hotels. The Hilton, two other major hotels and other high-rise buildings were ravaged by the fighting. The building was one of the three major hotels badly damaged, but not rebuilt, in Lebanon. Located in the City Center, the Hilton stood out in a major redevelopment area which, in recent years, had erased the scars of the 15 year long Civil Wa r.

Jan 1, 2003

By R. Blickensderfer

Maintaining an adequate supply of minerals and metals to meet national economic and strategic needs is the overall goal of the Bureau of Mines, U.S. Department of the Interior. One method of achieving this goal is to conserve scarce metals by cladding a plentiful base metal, such as iron, with a scarcer metal. To investigate cladding, a vacuum-rolling mill capable of rolling bimetal specimens at temperatures to 1,300° C in a residual gas pressure of 2 x 10-5 torr was established. Metals that were successfully bonded to iron included stainless steels, chromium, nickel, nickel alloys, copper, and several refractory metals including molybdenum and titanium. The effects of the rolling temperature, reduction in thickness, rolling speed, and residual air pressure on bonding strength and bend ductility of the bimetals were determined. Optimum rolling conditions produced bimetals with bond shear strength essentially equal to that of the iron base metal.

Jan 1, 1980

By M. O. Serbousek

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed an eight-piece precast reinforced concrete drift set for a small opening. Twenty-two sets of three different member sizes were tested to destruction under two loading conditions. A discussion of the test results and typical failure patterns is presented.

Jan 1, 1969

By G. V. Krishnan, L. Adler

A rock classification for drilling and boring is presented covering most equipment types and providing an estimation of the key parameters for operation, such as thrust and speed, and of performance such as penetration rate and bit life. Drilling and boring are significant and integral aspects of both the mining and heavy construction industries. Together these constitute over 20% of the G.N.P. Drilling and boring represent the most arduous mechanical processes performed in industry. Their misapplication quickly leads to equipment destruction, hazards, and to major delays. The classification is unified in two ways: 1) for a particular rock class several parameters can be estimated, 2) the classification integrates most excavating activities (i.e. digging, ripping and even blasting), and is derived from ground control. The rock classification provides a job property, based on fundamental and index properties, which yields quick and rough estimates of vital information. However it does not obviate the need for a more thorough analysis, and maintaining field records. BACKGROUND In order to adequately describe a drilling operation the conditions, activity, and equipment must be characterized. Of these the major independent variables are the conditions. Conditions focus on the geologic mass and also consider whether the site is surface or underground. The primary component of the geologic mass is the rock type, detailed below in Rock Characteristics. The other components

Jan 1, 1983

By Osamu Taki

This paper presents the system, the strength of column, the design concept, and the applications with four case histories from the past project as the general aspect of Geo-Column (trade mark of single soil-cement column by SCC Technology, Inc.). In the system, it shows the installation process and drilling/mixing tool with the mixing process. In the design concept, it shows how to design Geo-Column against the vertical and horizontal load. Finally, it shows the applications with four case histories, (1) building mat foundation, (2) isolated foundation on the pedestrian bridge, (3) bridge spread footing and slope erosion control wall in the channel, and (4) cut-off wall and shoring wall in the underpass roadway to the railroad.

Jan 1, 2000

By R. Fuenzalida

Since 2007, a number of Multivariable Predictive Control (MPC) Applications have been implemented on SAG mills, among others, within the Kairos Mining Concentrator Automation Program using ?Profit Controller?? and other tools comprising the ?Profit Suite??. Along this journey, several interesting and challenging issues related to SAG mill operation and control have been faced, which are relevant to be shared with the Mineral Processing community. These advanced control applications have an operational objective whose goal is to increase marginal profit on the concentrator, together with increasing mill stability. In regard to this objective, the issues to be presented and described are in direct relationship with ?Profit Controller? features and the SAG role; they are also stated and linked to get the most of the mill. Some conclusions and findings are also presented, leading to recommended practices on how to use the controller. These findings have also lead us to decide further actions to be taken on new applications to deploy and also on devising and implementing some complementary components to increase robustness of the overall automation solution, as well as reducing the need for operator intervention.

Jan 1, 2012

By R Aseervatham

The fast tracked mine development strategy attempts to blend feasibility studies and engineering/commissioning functions into a streamlined process. In this compressed process, environmental issues are difficult to control with respect to the optimisation of operational environmental performance. This paper presents a standard mine development process with specific focus on environmental issues, and contrasts this against Rio TintoÆs recent fast track experiences on the Hail Creek project (Australia), the Baranj project (India) and the Gokwe North project (Zimbabwe).

Jan 1, 1999

By B. K. Parekh, Z. Chen

INTRODUCTION The need for cleaning and recovery of fine (minus 28 mesh or 0.5 mm) coal fraction has increased in recent years. This results from realizing a substantial recovery of ultraclean coal from the waste stream improving overall Btu (heat) recovery, providing extra revenue for the coal industry. Also the potential of using the clean coal so obtained for making coal-water mixture which could replace oil. An additional benefit of recovery clean coal from the waste stream is reducing environmental concern of burning uncleaned coal and in waste disposal. Deashing of coal by physical beneficiation processes is limited by the degree to which ash components are liberated from coal. Conventional processes have been inefficient in terms of Btu recovery, for ultrafine coal. Chemical cleaning methods, which involves leaching of ash material from coal, have provided ultraclean coal at high Btu recoveries, are more costly than the physical cleaning methods. An advanced physical separation technique that appears to address the need discussed above is selective flocculation. This technique which has been successfully utilized in iron ore beneficiation offers the potential of processing fine and ultrafine coal to produce a clean fuel. OBJECTIVES The main objective of the present study is to investigate applicability of selective flocculation technique for recovery of clean coal product from the waste coal slurry supplied by the Peabody Coal co., from their three different coal preparation plants. It is also the objective of the program to conduct preliminary economic study of the selective flocculation process.

Jan 1, 2002

By J. B. Clark

In 1933, R. paris1 published a phase diagram for the entire Mg-Ca-Zn system. He reported the existence of a ternary intermetallic phase, Mg5Zn5Ca2, which formed a quasi-binary with the magnesium solid solution. Since then, no extensive work has been reported on the system. Recently however, indications of the existence of a second ternary in-termetallic phase in equilibrium with the magnesium solid solution led to a reinvestigation of the solid phase equilibria involving the magnesium solid solution. The 335°C (635°F) isothermal section was chosen for study. Metallography and powder X-ray diffraction were selected as the best mutually corroborating methods for determining the solid phase constitution. Seventy-six alloys were prepared from singly sublimed (99.95 pct) magnesium, electrolytic (99.95 pct) zinc and USP calcium. The analyses of some of the alloys are shown in Fig. 1. The alloys were melted in a graphite crucible under a chloride flu and chill cast in a split graphite mold. Dif-fusion couples (see Fig. 2) were prepared by casting molten Mg-20 wt pct Zn alloy around a cylinder of Mg-30 wt pct Ca alloy. The alloy samples and the diffusion couples were sealed under argon in Pyrex vials and annealed in a furnace capable of controlling within 1/2°C of 335°C. At the conclusion of the anneal, the alloy samples were quenched in ice water and the diffusion couples were air cooled. Procedures standard for magnesium alloys were used for metallographic examination. Powder X-ray diffraction patterns were taken on a G. E. camera with a 14.32 cm dim using nickel-filtered copper radiation. The redetermined 335°C (635°) section of the Mg-Ca-Zn phase diagram is shown in Fig. 1. TWO ternary intermetallic phases, designated w and

Jan 1, 1962

By H. Aykul

The choice of which mining method to use at many large surface coal mines is often dicated by what machinery is available or what experience the mine management can offer. One of the most significant surface coal mines in Turkey is owned and operated by the Turkish National Coal Board, located to the west of the city of Kütahya. The Seyitömer Lignite Enterprise (SLE) extracts low quality coal, the majority of which is supplied to an adjacent power station. The coal seems at SLE contain bands of ash which under normal mining conditions are extracted with the coal. This increases the ash content of the run of mine coal and results in lower efficiency at the power station and financial penalties for SLE. In this paper, therefore, selection of the best possible equipment and production method was identified to achieve high selective mining at SLE. The research found that two different high selective mining methods were suitable for selective excavation of the B3 seam, which were hydraulic excavator and truck and surface miner and truck combinations. It was also found that high selective excavation could provide the desired coal quality at 52% lower costs when the whole process (excavation, transportation, processing, etc.) was considered. Keywords: coal mining, surface mining, selective mining.

Jan 1, 2007

Jan 1, 1961

By Dale S. Preece

A Discrete element computer program named DMC @istinct Motion Code) has been developed for modeling rock blasting. This program employs explicit time integration and uses spherical or cylindrical elements which are represented as circles in 2-D. DMC calculations have been compared with measurements on bench blasts in the field with relatively good comparison. Structural rock mass characteristics have a significant impact on any blast and DMC has not, until now, included these effects. This paper discusses a recently added DMC capability for treating joints and bedding planes in bench blast simulations.

Jan 1, 1995

By Charles Sabine

The U.S. Bureau of Mines studied mines and prospects in the Bristol/Granite Mountains Wilderness Study Area (WSA) in 1982. The 45,000 acre WSA, located in the eastern Mojave Desert of California, is underlain by Mesozoic plutonic rocks with scattered roof pendants of Paleozoic (?) metasedimentary rocks. Two mines and six prospects are identified; one mine, the Silver Lode Mine, and a prospect of unknown name are adjacent to the area. The Silver Lode Mine has occurrences of silver, lead and zinc. Within the study area, the Comanche Mine has occurrences of iron and copper and the Iron Victory Prospect has an occurrence of iron. None are large enough to constitute a resource. Occurrences of magnesian marble at the Comanche Mine, Iron Victory Prospect, and elsewhere in the area contain too much MgO for commercial use other than agricultural soil supplements or crushed stone. Transportation costs to markets would exceed the value of the rock. At the Comanche Mine, situated in a roof pendant of marble, about 10 tons remain of a 110-ton pod of magnetite which contained 42.5% iron, and less than 50 tons remain of a mineralized fault breccia which averaged 2.5% copper and 0.3 oz/ton silver. Magnesian marble contained 41 to 45% CaO and 14 to 16% MgO. Primary and secondary silver, lead, zinc, and copper minerals are disseminated along altered joints and in quartz veins in quartz monzonite at the Silver Lode Mine, adjacent to the WSA. Analytical data are sporadic; samples contained as much as 0.12 oz/ton gold, 1.8 oz/ton Silver, 1.1% lead, 3.8% zinc, and 0.3% copper. Mineralized zones in the workings are not resources, but they might indicate possible silver-lead-zinc resources at depth. At the Iron Victory Prospect, lenses of magnetite and hematite with some chalcopyrite occur in a skarn lone in a marble roof pendant. About 110,000 tons of iron-rich rock, averaging 47.2% iron, are present; the largest lens contains about 30,000 tons. About 150,000 tons of magnesian marble, averaging 41.0% CaO and 11.7% MgO, are also present. Deposits of stone, and sand and gravel in the WSA are too distant from markets to be resources. Occurrences of energy minerals were not identified.

Jan 1, 1984

The lignite resource in the southern part of the South Island is New ZealandÆs largest source of indigenous primary energy. The ten deposits evaluated by the Liquid Fuels Trust Board (LFTB) have a total recoverable reserve of 6.2 billion tones equivalent to 74 000 PJ of energy or 20 times the original energy content of the Maui gas field. Updating the economics of the original LFTB studies indicates that lignite could be mined for between NZ$1.0 and 3.0/GJ. Its conversion to synthesis gas for production of petroleum products, chemical methanol, ammonia/urea fertiliser or electricity would be in the national benefit and likely to be commercially economic at todayÆs product prices.

Jan 1, 2005

By Louis Schaffer

The objectives of the research were to determine whether a model health and safety program could be defined in terms which would enable its application to mines of all types, and, if such a model program could be defined to determine through evaluations in two mining companies whether it would achieve measurable improvements. This volume describes the model, how it was applied in the field, and how it was evaluated. Anecdotal data to illustrate common kinds of safety problems and their solutions are included. The literature and field research that preceded the model definition is discussed in Vol. 2, which covers the period of September, 1980 to September, 1981.

Jan 1, 1983

By J. A. Every-Brown

Case studies are presented of three derelict sites in Kent and Essex that provide a good cross-section of opportunities for second-generation commercial uses of former chalk, limestone, clay and gravel workings. A 240 ha abandoned chalk quarry at Grays in Essex, now known as Chafford Hundred, is undergoing mixed development to include leisure facilities, a range of housing and commercial areas and an enhanced environment. The 120 ha of Stone Marshes now comprises the Crossways business park and the Dartford international ferry terminal. Reclamation and servicing required more work than had been anticipated and the fact that the area was within the green belt added to the delays, but Blue Circle was eventually able to provide a comprehensive development of the entire area to a high environmental standard. Stone Pit 1 landfill, at Dartford in Kent, is a former chalk quarry 40 ha in area and with an original average depth of 35 m. Landfilling commenced in 1976 and during the period 1979-1984 the site operator designed, developed and installed a gas collection and flaring system. From 1986 a gas plant supplied up to 5 000 000 therm/yr of landfill gas to a local cement works and in 1989 a 1 MW power generation scheme, later expanded to 3 MW, was commissioned. Gas is currently also supplied to a metal refining company for use in internal combustion engines

Aug 1, 1994