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By James A. Strosnider

INTRODUCTION The Metro Rail Project is approximately a 20-mile initial portion of Southern California's planned 150-mile transit network and will provide transit service to the dense population and employment centers within the Los Angeles regional core. The Southern California Rapid Transit District (SCRTD) has defined, as the first segment, a 4.4-mile five station rail line, which extends from the yard and shop area near Union Station to the Wilshire/Alvarado Station. Design packages are completed; utilities are currently being relocated; demolition is underway; early construction contracts have been awarded; and construction has started. This paper will describe the current status of the Metro Rail design and construction, after first briefly reviewing its history, objectives, and main components. PROJECT HISTORY The California State Legislature created the SCRTD in 1964 with a legislative mandate to design, construct, and operate a rapid transit system within the Los Angeles County area. To obtain the monies required to support this program, in June, 1974, Proposition 5 was passed by a solid majority, allowing a portion of state gasoline taxes to be used for rapid transit development. This measure provided a local source of funds for SCRTD to begin its rail rapid transit development program in Los Angeles.

Jan 1, 1987

By Joseph A. Dos Santos

The Expanded Conveyor Technology, a rationalization of the conventional conveyor technology, allows us to apply the theory and principles beyond the current (perceived) limits. This was first prompted by the writer's advancements in Sandwich Belt High Angle Conveyors. The introduction defines the Expanded Conveyor Technology and outlines the range of applicability for the wide variations in conventional and non-conventional conveyors. The writing deals with the theory and design of sandwich-belt, high-angle conveyors in the context of the Expanded Conveyor Technology, including the equations of friction, hugging pressure and the continuity of hugging principle; curvature constraints and criteria for tension, curvature, trough, and belt construction; and drive and tension analysis, load sharing and traction, including "derived load equivalents."

Jan 1, 2000

By Y. Zimmels, C. Feldman

Closed-circuit grinding processes are considered in the context of a reactor-separator circuit that involves multifraction streams and products. Because grinding circuits are low-efficiency, capital-intensive operations, modeling to maximize their economic return is appropriate. An attempt to develop and test such a model is presented in this work. The model relies on process simulation for both the mill and the separator, in conjunction with constraints imposed by product specifications. The grinding process was simulated using breakage functions, which provided complete data on the feed and product of the mill. A cyclone bank used as the separator was also simulated using known models. The overall process model provided a complete simulation of the multistream grinding and separation process. The process model was then incorporated into an economic model that predicts grinding cost, subject to process constraints, for a given set of operating variables. The model facilitates economic optimization of the grinding process as it relates to process variables and process hardware.

Jan 1, 1993

By T. L. Conley, J. J. Rozek

The $2 billion (A$) Melbourne City Link Project is one of the largest and most important metropolitan road developments ever undertaken in Australia. The project involves two three-lane vehicular tunnels totaling 5 km, constructed as deep as 65 m underground. The 3.4 km Burnley tunnel is one of the world's longest three-lane tunnels. The project is being delivered under a DBOOT [design-build-own-operate-transfer] process and all design and construction is performed to ISO 9000 standards. Tunnel excavation began in May 1996, and the tunnel will open to traffic in 1999. This paper focuses on the range of construction techniques utilized during construction.

Jan 1, 1999

By R. W. Seedsman

Mandalong Mine was originally planned to operate with panel widths of 250 m and a predicted surface subsidence in excess of 3 m. The consent conditions applied by the NSW government on this mine plan were very tight and, following a change in ownership, were considered by the new operator to present a number of unacceptable business risks An acceptable risk profile for the mine layout restricted surface deformations to less than 500 mm vertical subsidence, less than 7 mm/m tilt, and less than 5 mm/m strain. Empirical subsidence prediction methods indicated that it would be necessary to reduce extraction panel widths of 80 m - an uneconomic option. The application of a number of rock mechanics concepts identified that the local overburden geology could be exploited such that panel widths of up to 175 m could be possible. The 125 m width was selected as a low-risk introduction of this new subsidence prediction method. The extraction of the first 2 longwall panels has demonstrated the validity of the prediction subsidence method and has provided the opportunity to refine the selection of key input parameters. The impact of mining through a zone of thrust faults was successfully predicted. The mine is now planning the introduction of 160 m wide panels, and will review the associated subsidence impacts prior to any further increases in width.

Jan 1, 2006

By Richard A. Williams

The design, modelling and simulation of solid-liquid mixers remains one of the least advanced aspects of minerals processing, due to difficulties in quantifying complex slurry hydrodynamics from first principles, and in acquiring reliable experimental data for model verification and development. This contribution describes the application of electrical resistance tomography (ERT) for three dimensional imaging of the concentration of mineral particulates in a slurry mixer as a function of key process variables (particle size, impeller type, agitation speed). It is demonstrated how ERT can provide a wealth of detailed data to allow model development, which ultimately will lead to much improved design capabilities and the generation of mixing models which could reside within Particle Process Simulators. This principle is illustrated using descriptions of mixer behaviour based on an empirical approach, although the measurement methodology described is equally suited to development of computational fluid dynamics models, cellular models or design approaches based on artificial intelligence. The experimental data can be built into a visualisation data bank, which acts as a "process toolkit" by allowing a library of process responses to be catalogued. Hence these data can be accessed for the purposes of model development, equipment selection, optimisation of operating conditions or testing on-line control strategies.

Jan 1, 1995

By J. A. Organiscak

Data on dust-control practices, mining conditions and occupational exposures were gathered for approximately 80 underground continuous mining units. Despite silica contents on dust samples in excess of 5%, nearly forty units successfully maintained silica concentrations at or below 100 µg/m3 on a majority of occupational dust samples, while the remainder had difficulty maintaining this level. These two sample sets were termed Group A operations and Group B operations, respectively. This data was compared to identify causes of high occupational silica dust exposures. Analyses of dust-control parameters and geologies revealed only minor differences between these two groups. However, subsequent comparisons of face ventilation design showed considerable differences in silica exposure and silica content between Group A and Group B at the continuous mining machine and roof bolter operator occupations. These differences were minimal when using exhaust curtain ventilation with a dust scrubber. This face ventilation system can benefit operations having difficulty controlling silica dust exposure and silica dust content. The collected data also showed that occupational samples from Group B operations possessed generally higher silica exposures and silica content than similar samples from Group A. The single head roof bolter (helper) possessed among the highest silica exposures and silica contents in both groups.

Jan 1, 2002

By T. P. Weldum

INTRODUCTION Cleveland-Cliffs' operations in Michigan have been utilizing fully autogenous grinding for over four decades. This is but one of the key characteristics of the iron ore processing method that was developed for the extremely fine grained, low grade deposits of the region. Liberation size of the hematite and magnetite ranges from about 30 to less than 1 micron. Typical grinding fineness target to achieve silica grade in the concentrate is 80 to 90% passing 25 microns, or a P80 of approximately 20 microns. After primary grinding, the magnetite ore is first upgraded by rougher magnetic separation. It is then ground to final product size, sent through thickener-sizers utilizing selective flocculation, upgraded again by finisher magnetic separation, and then brought to final silica grade by reverse amine flotation. Hematite ore follows essentially the same route, less the magnetic separation stages. Concentrate is filtered and pelletized, along with con- trolled additions of fluxstone, to ready it for shipping. Iron ore pellets on the water of the Great Lakes have a value of approximately 1.5 cents per pound. GRINDING PROCESS DESCRIPTION Details of the Empire magnetite grinding process flowsheet have been presented by Greenwood and Rajala (1992), and more recently by Rose et al. (2002). The Tilden comminution process for either magnetite or hematite is essentially identical, with the exception of some variations in the excess pebble treatment methods (McIvor and

Jan 1, 2004

By Z. C. Liu, F. F. Roxborough, Lin. B. B.

The size distribution of coal cut by a mining machine is an important performance factor. It is well established that the main machine system variable that affects product size is the depth of cut. In essence, the greater the amount of coal won by a machine cutting at shallow depths, the greater the proportion of dust and fines produced. Conversely, deep cuts produce less dust and a generally larger product size. When cutting with a rotating drum, as well as with a longwall shearer, the depth of cut always varies from zero in the vicinity of the roof and floor, where most of the dust and fines are produced, to a maximum at mid-drum level. In this paper, minimizing the amount of shallow cutting with a cutting drum is discussed, and the effects of the drum cutting and design parameters on cross-sectional cutting area per revolution are analyzed. This study shows the following: •more shallow cutting occurs during the entry quadrant of a cutting cycle than during pick exit; •the ratio of the projected area of shallow cutting to the total projected area of cutting by a single pick per drum revolution is virtually the same for drums of different radii (however, it decreases as the maximum depth of cut increases); and •for double drums, the use of unequal drum diameters can reduce the production of dust and fines, compared to using drums of the same diameter.

Jan 1, 1998

By C. J. Savage

Rio Tinto Minera, S.A. operates in Southern Spain, at one of the most ancient mining sites in the world, using advanced computerised mine planning. This paper describes the development and application of the mine planning systems to the copper and gold/silver operations. It briefly covers the hardware configuration, and the advantages and improvements in mine planning achieved. The system's application started with the long term mine planning of Cerro Colorado (open pit) copper mine and was gradually extended to cater for the medium and short term planning requirements of the other operations of the Company. The base of the system is a mineral inventory established by the combined use of the geology and geostatistical methods, and compatible with the mine planning requirements. The planning system has three major components: one used for open pit design and long term mine planning, another used for blast evaluation and finally one used for short term mine planning. Recently, a fourth component has been added to the system for reconciliation between predicted and actual tonnages and grades. There is common data file transfer throughout the system.

Jan 1, 1986

By T. W. Oshnock

Pulverized coal (PC) and other injectants can be injected into the blowpipes of a blast furnace to decrease coke requirements. Throughout the history of blast-furnace development, there have been many attempts at injecting PC. In the 1960's a more serious effort was made to improve pulverized coal injection (PCI) technology. However, because of the additional capital requirements and the projected near-term inexpensive cost of other injectants, very few PC1 systems were installed. When the second oil crisis occurred around 1979, the shortage and high cost of fuel oil caused blast-furnace operators to operate without oil injection. It was soon discovered that blast- furnace operation without oil was not as smooth or efficient. Experiments with PC1 quickly showed that coal was a good replacement for oil which resulted in the rapid application of PC1 in both Europe and Japan. As a result, PC1 technology for blast-furnace operation has progressed rapidly during the 1980's. This paper will describe the worldwide status of PCI, characteristics of different PC1 systems, the effect of PC1 on blast-furnace process parameters, and the economic effects of using PCI. Results from the USS Blast-Furnace Thermochemical Projection Model comparing the effects of different coal properties and the effects of other tuyere injectants such as oil and natural gas will also be described.

Jan 1, 1988

By H. Reginald Hardy, Xiaoqing Sun

Rheological models are widely accepted as a means of describing the mechanical behavior of geologic materials. It has been found, however, that rheological models developed for a specific stress level on the basis of linear visco-elasticity generally are not satisfactory at other stress levels. It has been suggested that the parameters of such models should be functions of stress level (Hardy, 1965; Kim, 1971). In this paper, continuous functions of stress have been utilized to obtain the required variation of Burgers model parameters with stress level. The model developed using these functions provides a constitutive relation which reflects the real time-dependent behavior of rock materials. The new model is capable of predicting the creep behavior over a wide range of stress levels and also predicts mechanical behavior under different loading condition (e.g. constant stress rate). It is also interesting to note that the mechanical behavior of individual elements in the model appear to reflect the different stages of brittle fracture in rocks (Bieniawski, 1967), namely; crack closure, elastic deformation, stable fracture propagation and unstable fracture propagation.

Jan 1, 1986

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 Eugene F. Casey, John G. Ruggiero

INTRODUCTION Construction of tunnels in urban areas, especially reclaimed areas, pose many problems. The Red Hook Intercepting Sewer Tunnel, Contract 1A is a portion of the Red Hook Water Pollution Control Project located along the Brooklyn waterfront in New York City. This contract required the construction of a 2620 meter long (8600 L.F.), 3 meter (10-foot) diameter soft ground tunnel, eight Tunnel Manholes, nine Regulator structures, four Diversion and Tidegate structures and 765 meters (2500 L.F.) of branch intercepting sewers of diameters between .30 meters (12 inches) and 1.8 meters (72 inches). The construction contract bid price was $62 million with a duration of three years. The tunnel route crosses over five sets of operational twin cast iron subway tubes with clearances ranging from 4.3 meters (14 feet) to as small as 0.35 meters (14 inches). The route of the tunnel traverses historically interesting areas which have been reclaimed over the last 200 years. This paper is a case history describing the contractor's methods utilized to successfully advance the work through the above problem areas. LOCATION The Red Hook Intercepting Sewer Tunnel is located in the Borough of Brooklyn of New York City. The route is

Jan 1, 1981

By Jim Peregoy

INTRODUCTION Frontier-Kemper Constructors, Inc. is an Evansville, Indiana based heavy construction contractor engaged in projects for both the public and private sectors of the underground construction industry. Construction activities range from conventional shaft, slope, tunnel and chamber excavation through state-of-the-art mechanical excavation, ground freezing, standard support and structural concrete operations. Conventional excavation and concreting equipment, as well as raise boring machines, road headers, tunnel boring machines, and freeze plants are owned, operated, maintained and modified "in-house" to suit the needs of individual projects. The balance of this paper wilt present a general overview of the Frontier-Kemper planning and construction operations on the recently completed Phase II of the U.S. Army Corps of Engineers, John Day Dam, Juvenile Fish Bypass Project. General Project History The U.S. Army Corps of Engineers is responsible for designing, constructing and maintaining various navigation and impoundment structures on the nation's inland waterways. Maintenance involves both the work required to maintain the structure in fully-operable condition and the ongoing work required to maintain a positive impact on the environment. John Day Dam is located on the Columbia River approximately 95 km (60 miles) upstream of The Dalles, Oregon. It was constructed to: provide electric power to the Pacific Northwest; provide Locking for up-and-downstream bound commercial and private watercraft; act as a water impoundment structure to control flooding conditions; and to provide a source of irrigation water

Jan 1, 1987

By John W. Ahlrichs, E. Daniel Baker, Erich U. Petersen, William J. Tafuri, Douglas N. Halbe

The combined Bootstrap and Capstone deposits, located in the Bootstrap subdistrict (Section 10, T36N, R49E, M.D.B.M., Elko County, Nevada), are approximately 27 miles northwest of Ca-1I: Nevada. The contiguous Bootstrap Capstone deposits are located along the northeastern and northern flanks of Round Mountain, a horst block separated by grabens from the sheep Creek Mountains to the north-northwest and the Tuscarora Mountains to the east. Open-pit-minable gold reserves as of December, 1989, were 13.27 million short tons with an average grade of .057 troy ounces gold per ton and an overall waste-to-ore strip ratio of 2.5:1. Ore zones in Bootstrap are concentrated along north striking high-angle dikes localized along faults, while ore zones at Capstone are strata form and structural, occurring at the Devonian limestone/siliceous sediment interface and in high-angle fault-filling dikes. Pre-ore faulting produced a complex structural setting for Capstone, dominated by strong northwest fault sets cross-cut by northeasterly structures. Alteration associated with both deposits is silicification with a-strong argillic overprint. Dike emplacement, which post-dates silicification, marked the onset of mainstage gold deposition and argillic overprinting of silicified lithologies. Gold displays an affinity for moderately argillized sedimentary and igneous lithologies. Mineralogic and geochemical analyses of rotary percussion drill samples show good correlation between gold, silica, antimony, and arsenic.

Jan 1, 1990

By Charles A. Maliszewski, James M. Galvin, Gerhard Urschitz

With obvious signs of deterioration, the double track, historically registered Bergen Tunnels as part of the commuter rail system in New Jersey waited for rehabilitation for a long time. Serious water in filtration not only caused operational and safety hazards for the electrified rail line but also deteriorated and structurally compromised the tunnel lining. An innovative rehabilitation program was developed to enlarge the tunnel and to provide a new waterproofing system and final lining. For the rock excavation and support New Austrian Tunneling Method (NATM) principles were utilized, while water tightness was achieved by installing a PVC membrane waterproofing system followed by a reinforced cast-in-place final lining. Experienced on-site supervision generated additional savings during construction by streamlining support elements based on geologic conditions encountered.

Jan 1, 2003

By D. L. Purcell, B. T. McClure, J. McDonald

The U.S. Bureau of Mines has completed a laboratory evaluation of exhaust emissions from a diesel engine using an oxygenated diesel fuel. The fuels tested were soy methyl esters in a neat (100%) form and low sulfur, petroleum number 2 diesel fuel (D2). The engine tested was a Caterpillar 3304, indirect injection, naturally aspirated, 75 kW, diesel engine that is typical of engines used in underground mining applications. The objective was to determine the extent to which oxygenated fuels, such as methyl esters, reduce diesel particulate matter (DPM), and their influence on upon gaseous emissions such as total hydrocarbons, CO, NOx, NO2, formaldehyde, and other exhaust emissions. Heavy- and light-duty transient tests were used to simulate load cycles typical of mine applications. The soy methyl ester fuel produced greater amounts of volatile DPM (organic material) but much less nonvolatile DPM (carbon soot) for overall DPM reductions. A diesel oxidation catalyst (DOC) typical of the type commonly used in metal and nonmetal mines was tested with both fuels. The DOC further reduced the volatile and total DPM when used with the soy methyl esters, but increased the total DPM for D2 due to sulfate formation. The soy methyl ester fuel reduced CO and hydrocarbon, and NOx emissions. The DOC further reduced CO and hydrocarbon emissions.

Jan 1, 1995

By Louis W. Cope

Placer material, regardless of the value of gold, tin, titanium, diamonds or other value mineral it contains, remains worthless until the valuable constituent is separated from the bulk of the material. This separation is no mean task when considering that a gold placer containing 0.01 to 0.03 oz/yd3 of gold, which is the range of grade of typical placer deposits; yes, 1:3,000,000! It is a miracle that gold placer mining has ever been profitable. Added to the situation of minute quantities of gold are several other problems, such as the gold often being very finely divided, the association of boulders and clay, and running and/or ground water. As each placer deposit is individual and distinctive, many factors have to be considered in planning the method for gold recovery from the alluvial deposit. Previous chapters have shown that in the exploration and sampling stage, some knowledge of the amount of each size of coarse and fine material which occurs in the deposit as well as the size distribution of the discrete gold particles is determined. Unless informed to the contrary, as a general rule of thumb, plant designers will consider that 40 percent of the material will pass through a 5/8-inch screen or punched plate hole. Also that there may be an occasional nugget and normally considerable amounts of fine gold. The designer must

Jan 1, 1992

By Douglas J. Cork

Biohydrometallurgica1 processes in the areas of coal desulfurization (Hoffman, M.R., et al., 1981) and recovery of metals from metal sulfide ores (Lundgren, D.G. and Malouf E.E., 1983) are well known. In addition other areas of potential interest to the mining industries have been outlined (Spisak, J.F., 1979). For instance, scientists involved in this interdisciplinary field have endeavored to apply microorganisms to the problem of effluent sulfate disposal. This chapter assesses the feasibility of utilizing a particular two stage anaerobic microbial process to convert effluent sulfate to orthorhombic sulfur. Strong emphasis is given to the possibility of substituting this bioprocess for alternative gypsum synthesis and disposal methodologies commonly practiced by companies which emphasize sulfuric acid or ammonium sulfate leaching processes.

Jan 1, 1985