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By Desiree Willis

One of New York City?s largest subway projects is under way 43 m (140 ft) beneath the surface of downtown Manhattan. The East Side Access project, more than 30 years in the making, was halted after a partial excavation in the 1970s due to a lack of funding. The project, once dubbed the ?Tunnel to Nowhere,? has been revitalized into a groundbreaking subway line that includes unique tunnel boring machines (TBM), construction methods and muck removal systems. Project overview The East Side Access project involves construction of a new 6.7-km (4.2-mile) subway line needed to relieve heavy traffic congestion between the boroughs of Queens and Manhattan. The line will serve approximately 160,000 commuters daily between Grand Central and Sunnyside rail stations. Manhattan and Queens will be connected under the East River by the 63rd Street tunnel, a submersed double-decker tube. The submersed tube consists of reinforced concrete sections barged in place on the riverbed. The tube contains operational subway lines on the top deck, while the bottom deck (the ?Tunnel to Nowhere?) will become operational when the East Side Access project is completed in 2013.

Jan 1, 2008

By Craig Bournes, David Chapman, Michael DiPonio

Historically, boulders are a frequent source of problems in soft ground tunneling. During tunnel construction, the need to manually break and remove boulders as obstructions causes delays to the project. Repairs to a tunnel boring machine (TBM) can also be a source of delays. Managing these problems is difficult since normal soil investigation techniques do not accurately predict the presence or frequency of boulders. This has lead to considerable number of claims for extra costs and delays during the construction of soft ground tunneling projects. These issues are exacerbated in pressurized face tunneling systems where there is limited access to the TBM cutterhead for obstruction removal and/or cutterhead maintenance. The project team that built the Big Walnut Augmentation/Rickenbacker Interceptor (BWARI) Project for the City of Columbus successfully managed the design and construction of a 4,267 mm (14 ft) diameter soft ground tunnel with high boulder concentrations in a complex geologic setting. The management of the boulder issue tookplace during several phases of the project.

Jan 1, 2007

By Q. Wu

Neural network methodology is used to predict mean particle size resulting from rock blast fragmentation. A blast data base developed in a previous study is used in the current study. A part of this blast data was used to train a single-hidden layer back propagation neural network model for each of the similarity groups obtained in the same previous study. Levenberg-Marquardt algorithm provided the most stable and efficient training out of the four algorithms evaluated. An extensive analysis was performed using a part of the blast data to estimate the optimum number of units for the hidden layer for each similarity group. The remaining blast data are used to validate the trained neural network models. Capability of the developed neural network models is determined by comparing predictions with measured values and predictions based on one of the most applied fragmentation prediction models appearing in the blasting literature. Prediction capability of the neural network models was found to be strong and better than the existing most applied model. Diversity of the blasts data used is one of the most important aspects of the developed models. The developed neural network models are suitable for practical use at mines.

Jan 1, 2011

By A. D. Davis

The Gilt Edge Superfund Site is a former heap-leach gold mine that currently is being remediated in the Black Hills of South Dakota. Mine runoff water is treated before release from the site. The field pH, before treatment, is about 3, and the water contains arsenic and some heavy metals, in addition to sulfate concentrations of about 1400 to 1500 mg/L. In the Keystone area of the Black Hills, naturally occurring arsenic has been detected in ground-water samples from wells. Keystone City Well #4, which is not used currently, showed arsenic concentrations of 36 parts per billion (ppb) and sulfate concentrations of about 19 mg/L. With field samples of water from these sites, a limestone-based method was successful in reducing arsenic and heavy metals concentrations. The results are significant because previous research with the limestone-based method mainly had involved samples prepared with distilled water in the laboratory, in which interference of other ions such as sulfate did not occur. The research indicates the potential for broader field applications of the limestone-based removal method.

Jan 1, 2011

By Steve Dubnewych, Jon Kaneshiro, Calvin Jin

The Joint Water Pollution Control Plant (JWPCP), operated by the Sanitation Districts of Los Angeles County (the Districts), treats wastewater generated by over3 million people and processes wastewater solids generated by over 5 million people. The JWPCP Tunnel and Ocean Outfall Project, if constructed, would be one of the major marine outfall projects in the world. The new tunnel and ocean outfall system would provide relief to the existing outfall and allow inspection, maintenance, and repair of the existing tunnel and outfall system, portions of which were constructed as early as the 1930s. Geologic conditions are challenging along the alignments within the study are a being considered. Conditions include saturated alluvial soils, weak sedimentary rock, mixed face conditions, and squeezing ground conditions. Other significant challenges include the potentials for encountering up to 11 bars of water pressure, crossing seismically active faults, and encountering gassy and contaminated ground conditions. This paper discusses the details of the proposed project and the associated challenges.

Jan 1, 2007

By R. A. Gee, G. B. Ashton, S. T. Warren, P. N. Groves

Northside Storage Tunnel provides 500 megalitres (Ml) (130 million gallons) of storage capacity to capture stormwater/sewage overflows into Sydney Harbour. The6.6 m diameter TBM driven tunnel traverses Middle Harbour 85 m (280 ft) below sea level and through a sandstone/shale rock mass, highly disturbed by stress relief, 20 m(65 ft) beneath the base of the sediment filled palaeochannel. Target limits for inflow, groundwater drawdown and settlement of the valley beaches were achieved by systematic forward grouting from the TBM. Support included rockbolts, sets and shotcrete to carry rock loads, control block instability and spalling and to provide durability and serviceability. This paper describes the tunnelling and grouting works and their effectiveness.

Jan 1, 2001

By Michael B. Gilbert

The Woodbury L-73 Tunnel involved the design and construction of a 96-inch tunnel driven through 8,080 lf of very difficult ground conditions. Anticipated ground and groundwater conditions consisted of potentially flowing silty sand with cobbles and boulders, mixed face of sand and sandstone and full face of the St. Peter Sandstone. Actual conditions were similar, although the quantities did change from bid quantities. This paper presents the approach used for development of the GBR regarding risk management. The means of arriving at a fair compensation for variances from the baseline values to address the actual encountered tunneling behavior of the soil, boulder count and its effect on production rates are presented.

Jan 1, 2008

By Gregory R. Gorrell

The legal issues surrounding the regulation of subsidence are among the major concerns facing the underground mining industry today. Whether subsidence occurs almost immediately as a result of longwall mining or without warning as a result of room and pillar mining conducted years ago, the resulting disputes are highly controversial and typical of the disputes involving the competing interests of surface and mineral estate owners. Until recently, the law governing these disputes was firmly established under the common law. The passage of the Surface Mining Control and Reclamation Act 1, the utilization of new mining technologies, and the general heightened environmental awareness of our times, however, have interjected new issues into this area of the law. State and Federal court decisions and administrative agency interpretations have helped clarify some of the issues. However, as evidenced by the many recent lawsuits between operators, surface owners, and regulatory agencies, many uncertainties still exist.

Jan 1, 1986

By R. Schwarz, E. Pusch, A. Juch

"The paper describes in general the objectives, goals as well as theoretical background of "METSI"-project proposal submitted to German BMBF (Federal Ministry of Education and Research). The METSI project is a starting point for technology and know-how transfer of German water management and water treatment technologies to South African Mining industry. "METSI" is Setswana, one of the eleven official languages in South Africa, and means "water". It stands also for "Management System for the Implementation of Environmentally Sound Water Supply Technologies in South African Mining Areas with Involvement of all Relevant Stakeholders". The project focuses on development, design and implementation of mathematical models that consolidate and evaluate existing data and generate substantiated projections of "water" amount and quality. METSI covers a wide range of scientific, technical, social as well as economic questions related to "water in mining"."

Jan 1, 2011

By Shimi Tzobery, Jay Davenport, Raymond Henn, Sam Bandimere

Over the past several decades, the use of cement-based grouts using ultra fine cement as a replacement for portland cement has begun to gain acceptance as an alternative to chemical solution grouts used in permeation grouting. The amount of information currently available on grouts made with ultrafine cement is limited. The authors used a previously developed field testing program to perform additional tests to evaluate the permeation performance of portland and ultrafine cement-based grouts. For the first time, the 2003 testing program included an attempt to determine the 28 day compressive strength of the sand permeated by the grout.

Jan 1, 2005

By Bruno Bussière, Michel Aubertin, Anne-Marie Dagenais, Johanne Cyr

A five steps remediation program was commissioned in 1998 for the acid generating Lorraine mine site, located in the Témiscamingue region, Quebec, Canada. It included, as the main expenditure, a cover with capillary barrier effects (CCBE) used to limit oxygen migration. After construction of the cover, instruments were installed on site to monitor the CCBE performance. Modified oxygen consumption tests were also done to measure the oxygen flux through the cover. Results from water content and suction data, measured from 1999 to 2003, show that the capillary barriers effects are effective and that the water retention layer stays near saturation throughout the years. Oxygen fluxes estimated from monthly water content measures are generally below 10 g/m2/year. Results from modified oxygen consumption tests made on the site give almost similar oxygen fluxes. A two dimension numerical model of the Lorraine mine site was also constructed to verify that mathematical models could predict realistically the in situ conditions on such a large scale site. Numerical results obtained for three years show a good concordance between measured and calculated values. The results obtained form these different evaluation methods for the performance of a CCBE concur and confirm the efficiency of this cover in limiting acid mine generation.

Jan 1, 2005

By James W. Bass

Introduction Atmospheric fluidized bed combustion (AFBC) is an improvement over coal-fired boiler design. It offers several advantages over conventional boilers. AFBC can meet sulfur and nitrogen oxide emission regulations without the need for add-on flue gas treatment equipment. The relatively low combustion temperature inhibits ash melting, thus reducing slagging and fouling that can in turn increase a boiler's fuel flexibility. AFBC process The fluidized bed boiler that operates at atmospheric pressure on the fire side (AFBC) is relatively simple and no different in purpose from those pulverized coal boilers used by utilities today. Fluidized bed boilers can generate steam at the pressure and temperature needed by modern steam turbines. Only the firing system is different. In fluidized bed combustion, the fuel can be almost any coal or waste fuel. It is burned in the presence of a bubbling bed of limestone. Air is forced through the bed at a velocity sufficient to support the weight of the bed particles. When the bed is fully fluidized, it bubbles like a boiling liquid. Although the burning coal makes up less than 1% of the fluidized bed, all the bed particles are heated quickly by the turbulence. The calcium in limestone reacts with sulfur dioxide produced in coal combustion to form calcium sulfate in a dry solid state. In this way, sulfur emissions regulations can be met without installing flue gas desulfurization equipment. Boiler tubes submerged in the bed absorb heat directly from the turbulent solids. The heat converts water in the tubes to steam or superheats the steam. Because of the intimate contact of the boiler tubes with the fluidized bed, heat transfer is highly efficient. Consequently, less boiler tubing surface is needed to generate the same amount of steam as in a comparable pulverized coal boiler. The optimum temperature for sulfur capture is relatively low, about 815°C (1500°F) as opposed to 1370°C (2500°F) for pulverized coal boilers. This results in the formation of lower levels of NON. Because operating temperatures are below those that fuse coal ash, a single design can burn a variety of coals without slagging or fouling problems. TVA's AFBC development program Tennessee Valley Authority's (TVA) involvement in AFBC development began in 1974 and has addressed the technical uncertainties through a comprehensive program of design, experimental, and analytical studies. In 1979, TVA and the Electric Power Research Institute (EPRI) developed plans for a 20-MW AFBC pilot plant, a 10-fold scale-up over the next largest test facility. Pilot plant design features TVA constructed the pilot plant at the Shawnee Steam Plant near

Jan 4, 1986

By H. Razavizadeh

The recovery of copper from oxide ores containing from 2% to 4.1% acid-soluble copper from the Sarcheshmeh mine in Kerman province of Iran was investigated by agitation leaching in sulfuric acid media. Quartz, as a major constituent, and malachite, as the major copper mineral, were identified in the ore by X-ray diffraction (XRD) and microscopic studies. A series of leaching experiments on the ore was performed over a concentration range of 10 to 20 g/L and temperatures from 15° to 50°C for a maximum of 3 hours. An initial high dissolution of copper was followed by a very slow reaction. By increasing acid concentration and temperature, the dissolution rate of copper was accelerated. However, by increasing acid concentration, the acid consumption of ores was also increased. Surface morphology of solid residues at various leaching times was examined with a scanning electron microscope (SEM). All SEM micrographs of the partially reacted particles displayed a needle structure. The kinetic studies showed that the malachite dissolution rate could be modeled in two stages. About 85% of the malachite dissolution occurred in Stage 1, while the remaining 15% occurred in Stage 2. The data obtained for the leaching kinetics indicate that the dissolution for Stage 1 was a diffusion-controlled reaction with an activation energy of about 20.6 kJ/mole, and the dissolution for the Stag 2 was a chemical-controlled reaction with an activation energy of about 87.6 kJ/mole.

Jan 1, 2008

A glance at the following chart reveals that because of the continued poor economy, the slump in industrial mineral production continued into 1980. Gypsum was down 17% from 1979; cement down 9%, sand and gravel, 17%, and crushed stone, 11%. All these downward trends reflect the high interest rates and high costs that slowed construction starts. Domestic fluorspar was down 21% and imports off 14% due to the steel iudustry slump. However, potash production was up 8% and phosphate, 5%. Increased drilling activity spurred au increase in barite production of 25%. Most other industrial minerals posted losses with only a few insignificant increases. As expected, prices were higher, reflecting increases due to high costs for labor, supplies, and above all, energy. Increasing energy and transportation costs also had their effect on industrial mineral production. Railroad freight rates increased 16-22% including fuel surcharge; truck rates increased 11-14%a; and ocean freight rates increased 20% for finished goods. The 1979 shortage of boa and hopper cars did not continue into 1980-most likely due to low production of many of the hulk industrial mineral commodities. All in all, 1980 was not a good Year for industrial minerals.

Jan 5, 1981

This paper presents a virtual prototype for the stress analysis of cable shovel components based on combination of flexible and rigid body approach. The general mechanical system of the cable shovel is modeled as a multi-body system with rigid and flexible bodies. The relevant theories applied for the dynamic model are described in terms of Lagrangian multi-body dynamics and finite element method. A virtual prototype of the cable shovel is built in the Automatic Dynamic Analysis Mechanical System (ADAMS) environment, which allows visualizing the motion of general mechanical system and analyzing the dynamic stress of structural components of the cable shovel. An example is given to perform dynamic stress of durability analysis for the boom and handle. Attention of this study is devoted to the mechanisms of damage of the cable shovel and also the critical high stress areas. Keywords: Cable shovel, Von Mises stress, Virtual prototype simulation, Stress virtualization.

Jan 1, 2009

By Joseph Clare, Elizabeth Anderson, Mike McGinley, Ron Hines, Judy Cochran

The South Lake Union Pipelines contract for King County Wastewater Treatment Division and Seattle Public Utilities in Seattle, Washington included three 1.8 m (72-in)inside diameter microtunneled pipeline segments totaling about 793 m (2,600 lf).Tunnel alignments were within street right-of-way of heavily traveled urban roadways. Project challenges recognized in the design included: high groundwater levels; contaminated soil and groundwater; variable soil conditions, including fill; and timber piles and other obstructions remaining from historic land uses. The tunnels were built using a Lovat MTS Microtunneling machine, beginning in spring 2003. Conditions encountered during construction presented additional challenges beyond those anticipated in the design process, and were successfully addressed by the owners, designer, and construction management consultant all working with the contractor. Problems included highly variable soil conditions, cracking of reinforced concrete pipe joints during pipe jacking, a timber pile trestle uncovered during shaft construction, and obstructions encountered in the second and third microtunnel runs.

Jan 1, 2005

By I. Gombköto, G. Földing, G. Mucsi, B. Csoke, J. Faitli, B. Kovács

This paper summarizes the main achievements of our previous project entitled "Development of a technological system producing quality guaranteed fly-ash based binder". Furthermore, this study deals with the laboratory experience of lignite fly ash utilization for two different goals. On the one hand the fly ash was tested as a binder; on the other hand it was investigated as an underground mine backfill material. Considering the first goal, the utilization of a mixture of mechanically activated fly ash and lime for producing an independent binding composition has been assessed involving determination of relationship between the degree of activation of fly ash and the strength of the obtained concrete. The results confirmed that this hydraulic binder is suitable for construction of stabilization and capping layers or base layer. Regarding the backfilling application, this paper presents laboratory experiments, their results including settling tests, hydraulic permeability and strength measurements and dense slurry technology related results.

Jan 1, 2011

By V. Bush, T. G. Killingsworth, E. P. Ruffel

Effective and sustained corporate energy management programs are becoming a necessity for energy users as electricity deregulation laws are enacted on a state-by-state basis across the country and environmental regulations pertaining to emissions become more prevalent. The “Total Energy Asset Management” (TEAM) approach has been developed to assist energy end users with the development and implementation of corporate energy management programs designed to reduce energy risks and increase energy cost savings. This paper highlights the ways in which this approach can be applied to the mining industry while minimizing initial program implementation costs and increasing potential program benefits. Nearly the entire mining industry has become very focused on identifying opportunities to reduce costs per unit of yield. The industry as a whole has increasingly faced pricing pressures in large part due to the effects of global competition. The result of international marketplace participation and the emergence of higher efficiency recovery techniques have resulted in flat or even decreased prices for mining products. Thus, opportunities to reduce costs are actually opportunities to gain a competitive edge over similar mining operations. Due to the energy-intensive nature of many mining operations, the costs associated with energy are often a substantial percentage of operating costs. Therefore, it becomes very important to develop the corporate mentality that energy is an asset whose use should be optimized globally. In addition to the cost benefits of the TEAM approach, other benefits may occur such as reductions in facility greenhouse gas emissions.

Jan 1, 2002

By Richard R. Klimpel

Introduction Froth flotation is one of the most common unit engineering operations in use today. Its aim is to upgrade the quality of coal by removing ash/pyrite and separating selected minerals from undesired gangue materials. Flotation has been successfully practiced at the industrial scale for more than 50 years. Its use is increasing due to the ever decreasing feed grades of the coals and minerals being processed. Flotation has also shown itself to be a flexible process that lends itself well to many solid/solid separations. Thus, with surprisingly little equipment modification, separations can involve very different particle sizes and densities, and relative weight ratios of materials to be separated. In addition, the flotation process is economic, especially when compared to size reduction, its associated precursor process. Flotation also lends itself to continuous operations with a given equipment configuration. The operation must exhibit an ability to vary feed rate of solid to the process by as much as 50% without a total collapse of separating efficiency. In addition, the mechanical flotation cell is scaleable from 2.8 to 57 or 85 m3 (100 to 2000 or 3000 cu ft) with surprising ease relative to other unit engineering operations over the same relative size increase. The separating medium used is water. Most of the chemicals required - pH regulators, frothers, collectors, activators, and depressants - are all relatively inexpensive and common. They are not usually used in large quantities. Froth flotation is certainly one of the most versatile and forgiving unit operations in the chemical, mining, and agricultural industries. The problem with the industrial flotation process is that it is fairly easy to get reasonable results and relatively difficult to get excellent results. Why is it so difficult to fine tune the froth flotation process? There are some obvious reasons and a few not-so-obvious factors. The obvious category would certainly contain the tendency of natural feed materials (ores and raw coals) to have variable physical, metallurgical, and surface properties. This occurs even when special care is taken to minimize such differences with blending. There is another obvious reason for difficulty. An inherent broadness of the feed particle size range to flotation results from using any of the common industrial-scalefine grinding devices - ball-, rod-, or autogenous mills. Research has been done into the chemical reagent and equipment aspects of flotation. It has shown strong interactions (limitations) of chemical reagents and equipment on larger and smaller particles. The point is that current flotation practice works best on average- or medium-sized feed particles. The greater the amount of large or small particles, or of both large and small, the more difficult it is to achieve excellent flotation results. Other reasonably obvious factors include: • variations in mineral type and liberation sizes; • water chemistry variations such as those involving Ca", C03, or Fe", or various soluble metal cations; • the presence of stray organic materials such as returning soluble reagents or partially degraded reagents in reuse water; • the lack of reliable on-line instrumentation for monitoring and control; • frequent equipment malfunctions of all types; • excessive feed rates for installed plant capacity; • poor operator interaction with the process; and • poor reagent dosage control. There are less obvious, but real limitations to flotation. These are inherent in the design and operating characteristics of the most common cell design in use today - the mechanical flotation cell. Individual performance attributes of the chemical reagents used, along with their manner of use, also carry limitations. The bulk of this paper will deal with chemical reagents and their use. Chemical reagents In 1979, the author and his co-workers were asked to invent and implement, at the industrial scale, new flotation reagent chemistry. After reviewing some of the literature (Sutherland and Wark, 1955; Klassen and Mokrousov, 1959; M. Fuerstenau, 1962; D. Fuerstenau, 1976; and Leja, 1982), a series of carefully controlled plant scale tests were set up. These tests were designed to understand existing reagent scale-up from the laboratory to the plant. They were to quantify at the plant level the effect of some of the more important, controllable chemical reagent factors (frother and collector type, frother and collector dosage, pH effects). This is a learning experience that all researchers involved in flotation theory should experience. It quickly became apparent that: • because a factor is important

Jan 12, 1988

By Steven K. Duke, Jay Arabshahi

An economic, real-time probe drill monitoring system was developed for Metropolitan Water District’s Arrowhead Tunnels project to quantitatively evaluate ground conditions ahead of a TBM. This system digitally records hydraulic feed, rotation, and percussion pressures and calculates drill advance rates during drilling. These data are computer synthesized to develop a digital representation of the ground ahead, and the resulting “picture” of the ground is distributed to the project team to assist with tunnel construction decisions (i.e., targeting grout holes, optimizing mine-cycle lengths, and avoiding becoming stuck). The analysis and interpretation procedure has now been calibrated and refined using over 5,000 m (3 miles) of geologic face mapping data.

Jan 1, 2007