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By Ian Hooper, Alan Winter, Stefan Sadokierski, Craig Covil

The existing Tappan Zee Bridge was built in the late 1950s and has been working over its design traffic load for some time now. A new project, which is being jointly sponsored by the New York State Thruway Authority and Metro-North Rail Road, is looking at new alternatives to provide new road and rail crossings of the Hudson River. These include 2 to 5 mile and potentially longer tunnel crossing options that include hardrock TBM and EPBM opportunities. The paper describes the project needs and tunnel concept design work done on some of the alternatives. It also relates to the current EIS process for the project and talks about a possible double-stacked tunnel option. It also talks about the geology and environmental constraints relating to tunneling and provides and introduction to the tunnel ventilation work necessary for tunnel crossing of this magnitude. It does not report on the bridge engineering options being evaluated.

Jan 1, 2005

By H. A. Domian, H. Biloni, G. F. Bolling

Jan 1, 1965

By Timo Niitti, Antti Rinne, Janne Turunen, Sami Grönstrand

"This paper describes novel methods to enhance the flow dynamics of a mechanical flotation cell that can be applied to an existing installation. There are several reasons to alter the flow dynamics. The most common motivation is to improve the metallurgical performance of the cell, for instance, to improve the flotation recovery in particle size ranges that are normally difficult to recover.The flow dynamics enhancements are associated with the geometry of the rotor-stator area and additional features in the tank. The rotor-stator area has been modified to provide more concentrated turbulent kinetic energy or respectively more pumping efficiency with less attrition to the slurry. The tank can be fitted with various geometrical features, aimed to create a desired particle suspension profile. Depending on the targeted particle size range and application, badly selected or designed features can also have a negative effect on the metallurgical results.Besides new flotation equipment, the enhancements can be applied to existing flotation cell installations, thus enabling improvements in the mixing profiles, solids suspension, tank sanding and metallurgical performance of operating flotation circuits. Results of several tests carried out in existing plant operations are presented, concerning both flow variables and metallurgy.The common factor to above-mentioned enhancements is the use of modern computational fluid dynamics tools in the design phase, as well as the validation of the obtained CFD results in laboratory and production scale. Validated variables include mixing profile, power draw and local air hold-up.The paper demonstrates the effects of various flow geometries on the mixing profiles and metallurgical results of existing mechanical flotation cells. It shows how modern computational fluid dynamics analysis can be used to screen and select different approaches before carrying out costly trial-and-error experiments in plant scale."

Jan 1, 2006

By R. A. Wattenbarger, H. J. Ramey

The trend in gas well testing has been to rely more on the early-time flow data of drawdown and buildup tests than on stabilized flow tests. The stabilized testing methods often are not adequate for complicated modern gas reservoirs because many of these reservoirs have extremely low permeabilities and the transient flow period of a well test can last for days or weeks. It has become common to augment the flow capacity of gas wells by hydraulically fracturing their producing formations. In deep reservoirs the induced fractures are generally vertical and tend to follow a single plane of weakness. The presence of a vertical fracture at the wellbore complicates the transient flow behavior of a low permeability gas well. The flow is further complicated when turbulence occurs near the wellbore. Russell and Truittl published transient drawdown solutions for vertically-fractured liquid wells. They developed methods of drawdown and buildup testing utilizing these solutions, which were based on numerical simulation. Clark2 applied the basic Russell-Truitt solutions to analyze fractured water injection wells by falloff tests. Field examples were given to substantiate the method of analysis. The Russell-Truitt solutions and well testing methods can be extended to gas well flow. Millheim and Cichowicz3 presented the drawdown equations for *Now with Scientific Software Corp., Denver. ideal gas flow, including the effects of formation damage and turbulence. Two actual field cases were presented, both of which exhibited extensive fractures and turbulent flow. For the pressure range of these well tests, the use of ideal gas equations was acceptable. These field cases were significant in being the first published data showing the occurrence of turbulence in fractured gas wells. We, also, observed such cases in practice. Our purpose here is to extend the theory of fractured gas well testing to the flow of real gases. To determine the effects of wellbore storage and turbulence on well test interpretation, we developed a finite-difference model to simulate well test conditions. Since gas wells usually are widely spaced and have high compressibility, the emphasis has been put on the early transient behavior before the effects of the outer boundary are noticeable at the wellbore. The Mathematical Model The geometry of our mathematical model is similar to that used by Prats.4 The well is centered in a circular uniform reservoir. A vertical fracture of infinite flow capacity penetrates the formation and passes through the wellbore. The wellbore itself is not important. Fig. 1 shows a sketch of the problem. Fig. 2 shows the idealized model. The equation for the flow of real gas in a porous medium with uniform porosity, permeability and thickness is5-7

Jan 1, 1970

The southern portion of the Swan Coastal Plain, a geomorphological element formed since late Tertiary times, contains commercially exploitable accumulations of ilmenite, zircon, rutile and monazite associated with a series of raised shorelines. The location of the deposits is controlled by a locally outcropping Archaen granite/ granulite complex and a sea current pattern determined by local geography and a prevailing wind direction. A progression from medium to high titanium ilmenite is evident parallelled by progressive leucoxenisation as the age of the deposits increases. Variations in trace element content accompany this process. Circulating groundwater has caused vertical mineralogical variations within individual deposits and by precipitation of iron has formed layers of hardpan.The Geographe Bay deposits are of important economic significance.INTRODUCTIONObservations made during the course of a brief survey of the southern portion of the Swan Coastal Plain provide an outline of the geology and mineralogy of the mineral sand deposits of the area. This preliminary study will require considerable modification in the light of more detailed work in the future.REGIONAL GEOLOGYThe Geographe Bay area is situated in the south-west corner of Western Australia between longitudes 115° O'W. and 116° O'W. and latitudes 33° 15'S. and 33° 45'S.The general geology of the area is shown in Fig. 1 where the control of the physiography exercised by the Cape Leeuwin-Cape Naturaliste basement ridge is readily apparent. Between this ridge and the Precambrian east of the Darling fault lies the southern part of the Perth basin which contains outcropping Jurassic to Recent sediments and lavas (McWhae, et al., 1958).The Leeuwin-Naturaliste ridge is the exposed portion of L Assistant Production Managcr. Laporte Titanium (Aust.) Ltd.

Jan 1, 1964

By M. van Schoor

The bulk of the world?s platinum production originates from the Merensky and UG2 reefs within the Bushveld Complex, South Africa. Both the Merensky and UG2 reefs are disrupted by faults, dykes, potholes and iron-rich ultramafic pegmatite bodies (IRUPs)?features that impact negatively on production, planning and safety. It is therefore advantageous to know of their presence and geometry ahead of mining. To date, no geophysical technique has been successfully applied to the routine mapping of mine-scale potholes and IRUPs. These disruptive features may vary from a few metres to several tens of metres in diameter. In this paper the applicability of in-mine electrical resistance tomography (ERT) to map potholes and other disruptions to the continuity of the Merensky and UG2 reefs ahead of mining is demonstrated using two case studies.

Jan 1, 2005

By Braden Lusk, Paul Sainato, Josh Calnan, Hiago Vasconcelos, Luis Felipe Marinho

"Blasting and rock fragmentation is one the most important unit operations in mining. Since itsintroduction into the mine production cycle, mining has become more efficient in mineral production(Hartman, 2002). Widely used with the main objective of breaking rock mass in smaller fragments to be loaded and hauled at a minimum cost, blasting is optimized when stemming materials properly confine drillholes charged with explosives. Halim Cevizci (2013) performed a stemming application using Gypsum plaster, a kind of material that exhibits solid-like behavior when it is dry. Based on his theory, the present article reports an experiment using another type of material that shows similar behavior, non-Newtonian fluids. The primary goal of this study is to measure the confinement effectiveness provided by a non-Newtonian mixture as the stemming component. The study also analyzes the explosives’ energy propagation throughout the rock mass relating to the stemming materials applied. Currently, mining literature recommends the application of dry granular materials in stemming columns, because of its inertial and high frictional effects (Hagan, 1973). However, the test verified that the mixture added to the stemming column was able to reduce energy and gas losses to the atmosphere, because of the liquid’s property of filling voids in the material. The solid-like behavior of the non-Newtonian mixture was investigated for its capability to improve borehole confinement, since the mixture reacts like a solid when under shear stress. The results were compared to those from sand and air stemming applications, configured in different arrangements. It was concluded that the non-Newtonian mixture yielded high results due to its better confinement effectiveness, a reduction of air overpressure, and an increase of the strain propagation and ground vibration throughout the rock."

Jan 1, 2016

Jan 1, 1997

By Herbert H. Kellogg

The chemistry of sulfide roasting is analyzed to show those aspects of performance which Thecan be predicted from considerations of thermodynamic equilibrium. It is concluded that equilibrium calculations can serve as a yardstick for prediction of roaster-gas composition and sulfate formation in the calcine for fluid-bed roasting practice. A method of calculation which combines the equilibrium and stoichiometric factors is outlined, and illustrated by an example from the roasting of Cu-Fe sulfides. ON first examination the roasting of sulfides would not seem to be a process to which equilibrium calculations could be applied to yield results of practical value. The burning of sulfides is an ex-tremely spontaneous reaction, excess air is always used to obtain rapid reaction, and in most traditional roaster designs (hearth roasting) the temperature and gas composition vary widely from point to point in the roaster. These are all conditions which promote a non-equilibrium state in the roasting process. However, the introduction of the fluid-bed roaster1 has brought to roasting practice new conditions of operation, so that equilibrium calculations can be used to predict certain limited aspects of practical operation. The fluid bed is characterized by uniformity of temperature, gas composition, and calcine composition from point to point throughout the bed. These relatively uniform properties of the bed make the meaningful calculation of the equilibrium state of certain reactions in roasting possible. It is the purpose of this paper to analyze roasting from an equilibrium viewpoint, to show where the method may be expected to yield valuable information, where it fails, and to outline methods of calculation. Main Roasting Reaction The reaction MS (s) + 3/2 0, = MO (s) + SO, [I] might well be called the main roasting reaction. It adequately accounts for the well known facts that metal sulfide and air are the main reactants, and metal oxide and SO, the main products. Deviations from this simple stoichiometry will be discussed under side reactions. For all metal sulfides, Reaction 1 is strongly exothermic and the equilibrium position is far to the right. Since the reaction is exothermic, the equilibrium shifts in the right-to-left direction as the temperature is raised. However, at all practical roaster temperatures (between 500" and 1200°C), the amount of this shift is small, and the equilibrium position remains far to the right. The main roasting reaction is essentially irreversible, and the application of equilibrium considerations to this reaction will not be! a fruitful field of investigation. A knowledge of the rate of this reaction. although not the proper subject of this paper, is of great importance to the roasting process. Analysis of the factors which influence this rate shows that: 1) The rate will increase rapidly with increased temperature. 2) The rate will be proportional to the partial pressure of oxygen at the surface of the reacting particle. Because of diffusion effects, the partial pressure of oxygen at the particle surface may be considerably less than in the bulk of the roaster gas. For this reason, intimate contact between gas and solid and high relative velocity between gas and solid, such as can be obtained in a fluid bed or flash roaster, will markedly increase the rate of reaction. 3) The rate will be proportional to the surface area of metal sulfide. Therefore, smaller particle size will permit a more rapid rate per unit of weight. To achieve practical rates of roasting the partial pressure of oxygen in the roaster gases must be maintained at a finite level at all times. Even where the gas-solid contact is very good, as in the fluid-bed roaster, the oxygen content of the gas must not be allowed to drop below some limiting value (perhaps 1 pct), or the rate of the main roasting reaction will become too small for practical operation. Side Reactions in the Gas Phase The gas phase during roasting of metallic sulfides contains the elements oxygen, sulfur, nitrogen, by-

Jan 1, 1957

By Bill Cain, R. John Caulfield, D. Scott Kieffer

The East Bay Municipal Utility District is undertaking seismic upgrades of the Claremont Tunnel in the San Francisco Bay area. The tunnel carries treated water across the active Hayward Fault to supply a major metropolitan area. Studies indicate the tunnel could be severed by fault offset during a major seismic event. A design approach to achieve limited operation of the tunnel following fault displacement has been established and design details are currently being evaluated. This paper describes the project, the design approach, and summarizes significant construction constraints.

Jan 1, 2001

By Peter Zhang

Pumpable cribs are being increasingly used in longwall tailgate entries and bleeders for roof support under abutment pressure. Their high peak capacity and confinement-controlled yield characteristics from reinforced-bags make them relatively safe and reliable standing supports for highly productive longwall panels. The pumpability of crib material over a long distance from the surface greatly reduces material handling and makes the underground installation more efficient and flexible. However, the performance of pumpable cribs is dependent upon crib properties, crib pattern, quality of installation, and geological and mining conditions. For proper crib selection and safe support design, it is critical to understand the basic technical requirements and performance of pumpable cribs in longwall tailgate entries and bleeders. Based on more than 10 years of experience using pumpable cribs for longwall standing support, the requirements and performance of pumpable cribs in longwall tailgate entries and bleeders under different mining conditions are presented. Experience shows that the load-displacement curve from full-scale lab testing is a good indicator of pumpable crib suitability for certain applications. Crib peak capacity, stiffness, and residual characteristics define its applicability to certain gate entries and bleeders under different cover depth. Crib pattern and spacing can be determined by abutment pressure level, roof, floor, and rib conditions, local roof stability, and ventilation requirements. To achieve proper in-situ performance, quality control of crib installation is also important.

Jan 1, 2012

E. W. Stutchbury (Internationa~ Oombustion Aust. Ltd.) : Mr. Callcott made particular mention in his paper of erosion in primary air fans which are placed after the mill discharge. He adds that subsequent reduction in plant performance and resulting increased maintenance costs occur. It is generally assumed that this statement is substantially correct as the fan handles the complete output from the mill, but with modern materials, reduction in performance and subsequent .maintenance are not now a problem. This consideration of handling the pulverised coal in the fan is more than offset by the advantage of operating the mill under suction which results in cleaner operating conditions, simpler feeder arrangements and elimination of complicated seals on the mill.and feeder unit. It should be specially noted that whereas mill exhausters in the past have used chequer plate blades (sometimes with the addition of hard facing by electrode deposit) it is modern practice to provide fan blades of up to 1 in·. thick Ni-hard suitablyheat treated, with the circumferential section of the fan also in Ni-hard. By the use of this material large power...

Jan 1, 1957

Performance of Dry Separation Processes in Cenospheres Recovery from Coal Fly Ash

Sep 13, 2010

By W. H. Schiffbauer

NIOSH has developed an active proximity warning system called HASARD (Hazardous Area Signaling and Ranging Device) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels which are calibrated to identify levels of danger. The receiver outputs can include visual, audible, and vibratory indicators and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak, and on a highwall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed and proved to be rugged enough to withstand the harshest of production environments.

By N. Sutcliffe

Refractories and slags play a vital role in the production of stainless steel. They are in intimate contact with the steel at temperature, and chemical reactions between the three can and do occur. These interactions can be beneficial, in the case of active tundish and ladle slags, and negative in the case of refractory erosion and slag entrapment. This paper presents the results of both plant trials and laboratory investigations of steel/refractory and slag/refractory interactions. The interaction mechanisms observed are described leading to selection criteria for new refractory products. Keywords: slags, steels, refractories, reaction mechanisms.

Jan 1, 2004

By R. W. Parsons

The over-all apparent single-phase permeability of fracture-rock systems was studied using two different two-dimensional models. In a strict sense the results are applicable only to these models, yet may give some insight into real reseruoir behavior. The regular fracture-matrix model can have any number of regular fracture sets. All fractures within each set have the same orientation, width and spacing. The gross behavior is amlytically equivalent to that of an anisotropic permeable medium. In the heterogeneous fracture systems, individual fracture conductivities vary within a two-dinensioml network pattern. A computer program calculates the overall permeability after the conductivities are randomly placed in the network. The calculated permeability depends upon the distribution of these conductivities and the particular fracture pattern into which they are placed. Although detailed information on actual reseruoir fracture systems is not available, this study shows how some of the possible variables may affect obserued gross reservoir characteristics. INTRODUCTION Characteristics of reservoir rocks are determined by direct (core analysis) or indirect (logging and production tests) examination. Both methods, singly and together, are widely used in reservoir evaluations. For fractured reservoirs a problem exists in relating characteristics of cores to the in situ reservoir properties. Knowing fracture characteristics can be of value in determining production mechanisms. Because of the limitations of observation, the intimate details of a fractured rock system will never be known. One approach in analyzing fractures is to study the behavior of some conceptually simple models. The two models analyzed contain features which may be realistic, yet are mathematically tractable. Flow is considered in two dimensions only, with the plane of interest at right angles with the fractures. This concept represents the horizontal flow in a reservoir system with the fractures oriented vertically. Only single-phase, laminar flow is considered. The regular fracture-rock system permeability is calculable from a simple analytical expression. The heterogeneous system requires a computer program for calculating overall permeability.

Jan 1, 1967

By M. M. Singh, J. W. Brown

Three rocks of highly varied physical properties are selected for the first reported experimental study concerning microseismic activity of rock under tension to determine the effects of static fatigue, loading rate, repeated loading and rock anistropy compared to compression and bending loads. The microseismic method of detecting rock under deformation may be a great potential tool in surveillance and location in situ of dangerously stressed strata, as well as predicting rock failures. Noises emitted under load or the rate of energy (energy of noise pulses generated per unit time) are computed for varying conditions. The tests are conducted at constant load on a dead weight loading machine to eliminate all possible extraneous noises — an indispensable precaution — at various load levels. Experimental results are reported including the relation of total energy emitted to tensile strength of rock and the possibility of simulating a phenomenological model for microseismic activity. Plots of some of the experiments are included. INTRODUCTION Rock failure, whether on a large scale faulting in the earth's crust and rock bursts in mines, or on small scale ruptures of laboratory test specimens, generates transient vibrations in the rock mass. Mechanisms of intermittent deformation, such as twinning and cracking through and between mineral grains, also produce similar vibrations, but of very small amplitude. Such vibrations from both deformation and failure are referred to as microseismic activity, rock noise, or occasionally seismo-acoustical activity. An individual rock noise is sometimes

Jan 1, 1967

By J. Dahner

Total milling cost is composed of energy, liner and grinding media costs. In primary high ball load milling, the grinding media play the biggest role in total milling cost. This cost can be drastically reduced by improving the impact condition inside the mill. The impact condition inside the mill is influenced by shell liner design (as well as feed end and discharge design) and the type of discharge. The improvement of the impact condition will result in a significant decrease in grinding media consumption. The softened impact condition allows for better alloy optimization, resulting in a further reduction in grinding media consumption. Optimized liner design can also improve energy consumption as less energy is wasted in the projection of the grinding media. Magotteaux utilizes tools to simulate and show the grinding media trajectories for shell and end liners. This paper will present some practical examples where the media and energy consumption can be or has been reduced by optimizing liner design. Keywords Comminution, grinding, liner design, grinding media wear.

Jan 1, 2011

By Steve Wilson, Bern Klein, Jeff Drozdiak, Stefan Nadolski, Andrew Bamber

"In the adaptation of high pressure grinding rolls (HPGRs) to hard-rock mining applications, circuit development has mainly focused on placing HPGRs in the role of tertiary crusher in the preparation of ball mill feed. In order to take advantage of the potential energy benefits associated with HPGR and stirred mill grinding technologies, work was done to investigate the potential of and resultant energy benefits of placing the HPGR in series with a high speed stirred mill in replacement of the conventional cone crusher / ball mill arrangement. The proposed circuit was designed to operate with two stages of HPGR grinding followed by high speed stirred milling.Using a pilot-scale HPGR unit inline with a 20 liter stirred mill, the design criteria, circuit arrangement and consequent comminution energy requirements for a circuit processing copper sulphide ore from Teck Resources’s Mesaba Copper project were determined. These results were then compared to two other circuits, an HPGR / ball mill circuit and a conventional crusher / ball mill circuit processing the same ore.The testwork indicated at a proof-of-concept level that the HPGR / stirred mill circuit could potentially be appropriate for this duty and further work on the concept is merited. While the results indicate that the HPGR component of the circuit was more energy efficient than conventional cone crushing, the energy efficiency of the stirred mill was found to be lower than that of a comparable ball mill undertaking the same duty. However, increased energy efficiency of the stirred mill portion of the circuit is possible with further optimization and further work on the concept is indicated."

Jan 1, 2010

By William R. Yernberg

In October 1999, Liebherr-America, Liebherr Construction and Liebherr Mining Equipment held anopen house at its Newport News, VA, plant. The open house was held to celebrate the company’s50th anniversary and to demonstrate the new TI 272mining truck. Attending the open house members of the media, vendors and company representatives from all over the world. In his introductory comments, company president Peter Eller announced Liebherr’s dedication to expanding its presence in North America. Liebherr now has 30 dealers across the United States. As part of the open house, a brief history of Liebherr was presented, beginning with its creation in1949. Liebherr engineering and sales representatives were available to answer questions.

Jan 1, 2000