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By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

By Patricia Pride, Kurt Bettger, Jack Raymer

"INTRODUCTION The Jefferson Barracks Tunnel is in the final stages of design and is expected to go out to bid in the summer of 2016. The project is located in south St. Louis County along the west bank of the Mississippi River, about 13 km downstream of the St. Louis Gateway Arch. The project consists of a deep sanitary sewer tunnel, a deep pump station and several intakes. The intakes will divert sanitary flows into the tunnel and the tunnel will convey the flows by gravity to the Lemay No. 3 Pump Station, which will pump them up into the Lemay Waste Water Treatment Plant. The tunnel is about 5.4 km long and will be lined with 84-inch (2.1 m) fiberglass pipe. It drops at a gradient of 0.1 percent from south to north and will be bored through strong limestone using a hard-rock tunnel boring machine (TBM). The diameter of the TBM is anticipated to be about 3.4 m. The Owner’s original concept was for a relatively shallow tunnel so as to minimize construction and pumping costs. The preferred alignment ran close to the river, next to the existing force main, which was to be abandoned. Keeping the tunnel close to the force main would reduce the amount of shallow sewer work needed to connect the existing feeder sewers to the new tunnel. Several geotechnical investigations were performed, with shallowly focused geophysics and the borings all going exactly down the conceptual tunnel depth. Limestone bluffs run along the Missouri side of the river. These bluffs are pockmarked by sinkholes and riddled with karst. Large, well-known caves occur both north and south of the alignment. Karst features, including deep crevices and possible caves, were found in those early geotechnical investigations. Many of these features extended well below the level of the Mississippi River and would have been encountered by the tunnel. If a large crevice or cave were encountered, then the inflow of mud and water into the tunnel could have been large and possibly uncontrollable. Something had to be done to mitigate this situation. Pre-excavation grouting was considered, but the program would have been huge and extremely expensive. Using a closed-face TBM with bolted and gasketed lining was also considered, but that too was both risky and extremely expensive. The Owner could have abandoned the tunnel altogether and built a new force main, but that would have brought a whole new set of problems and was undesirable to the Owner. The last option was to move the tunnel away from the karst."

Jan 1, 2016

By R. W. Smith

The electrokinetic and flotation behavior of the green alga Chlorella vulgaris was studied in the absence and presence of Pb(II), Al (III) and flotation collectors. It was found that the presence of Al (III) is necessary for good flotation of the organism whether or not Pb(II) is present when dodecylammonium chloride or sodium dodecylsulfate is used as collector. Best flotation using dodecylamine is at about pH 8 and best flotation when using sodium dodecylsulfate is at about pH 4. It appears because of the small size of the organisms that the Al (III) is necessary for flocculation to enhance bubble-cell contact and C. vulgaris removal from water. When N-dodecyl-2-aminoproprionic acid is used as collector good flotation occurs at about pH 4 without the addition of Al (III).

Jan 1, 1990

By Sadatoshi Ohmori, Karen Shinoda, Nobuharu Isago

Method of tunnel excavation is generally classified such as full-face excavation, bench-cut excavation, diaphragm with center pillar excavation, center drift advancing excavation and so on. These excavation methods should be selected properly in terms of ground condition, the area of tunnel section, the arrangement of construction. Center drift advancing excavation method in mountain tunnel construction, is often applied under quite weak ground condition, prior to the main tunnel widening excavation. Recently, the advancing drift is for the excavation of extreme larger section in main tunnel to confirm the stability of face. In addition, we make advancing deformation occur in drift when the construction was done in poor ground like squeezing and swelling ground, and the force occurred in main tunnel was expected to reduce by the effect of ‘dodging’ for support structure. Mechanical relation between drift and main tunnel has been mainly grasped on past experiences in Japan. However, the characteristic of tunnel enlargement was partially discussed by using the three dimensional analysis and the result was grasped by past experiences on the basis of each tunnel construction. It is considered that the natural ground stress is normally released as the advance displacement, but it was released after the main tunnel widening, causing a displacement and deformation increase. Up to now, the construction practice has shown the reduced displacement during the main tunnel widening excavation by the drift, and the numerical analysis agreed with above observation. However, there is no report found that the displacement and deformation at the time of widening excavation of the main tunnel become larger in case of a drift application. In Kyusyu area, western part of Japan, the northern part of Yoshinomoto tunnel was applied an advancing bench-cutting method for a center drift for the purpose of obtaining the geological information for support selection of the main tunnel in widening excavation. The shape of center drift was a perfect circle with a diameter of 4.0 m or 6.0 m and the same temporary support regardless of the geological situation. As a result, the displacement and deformation of the main tunnel after widening excavation were larger than the section where the center drift was not applied. Furthermore, the displacement and deformation of the main tunnel after its widening excavation was considered larger in the section where the cross-section of the center drift with 4.0 m diameter was applied than one with 6.0 m. Therefore, the center drift with a high rigidity support structure had the effect of suppressing the advancing deformation prior to the main tunnel widening excavation.

Jun 13, 2021

By S. L. Bessinger

Introduction In the design and specification of a ventilation system for an underground mine, it is necessary to make reasonably accurate estimates of the pressure losses in the various airways of the mine. These estimates can be made with little difficulty for open airways with simple geometric cross-sections, such as those cut by continuous miners or tunnel-boring machines. The situation is much different on a longwall face, where the airway's complex geometric cross section and the presence in the airway of obstructing equipment having a variety of shapes make it difficult, if not impossible, to estimate pressure loss using traditional methods of calculation. Head losses in mine entries are calculated using Atkinson's Equation. [22H= KPLQ (English) H= KP 3Q (SO (1) 5.2AA] where H = pressure loss, in. of H2O (Pa); K = friction factor, lbf•min2/ft4 (kg/m3); P = perimeter, ft (m); L = airway length, ft (m); Q = airflow quantity, ft3/min (m3/sec); and A = flow cross-sectional area, ft2 (m2) In this equation, the friction factor, K, is an empirical constant that describes the aerodynamic roughness of the airway. Typically, the K-factor for a given airway is determined by measuring the factors H, P, L, Q and A in Equation (1) and calculating K. Tables of friction factors calculated in this way are found in textbooks and handbooks that deal with mine ventilation analysis. Unfortunately, very few K-factors have been measured on longwall faces, and the accuracies of those that have been measured are entirely site specific, because of the wide variety of equipment found on longwalls. The development of a technique for prediction without mine-site measurements of the friction factor for any longwall face, regardless of its configuration, will thus be very useful in the design of ventilation systems for mines in which longwall mining is practiced. Calculation of pressure losses using Atkinson's Equation (1) and empirically determined K-factors provides accurate and useful approximations in cases where the airways have relatively simple cross sections. However, a careful analysis using the principles of fluid mechanics shows that such calculations are based on two assumptions that are not strictly correct when there are obstructions in the airway. The first assumption is that the air velocity distribution in the cross section, particularly around the perimeter, is uniform. This assumption results from the fact that the tabulated K-factor values found in the literature are based on field measurements with uniform conditions. Such uniformity does not exist in longwall airflows. The second common assumption is that the K-factor, and corresponding head loss, is independent of the Reynolds Number (NR) for a given flow. In fact, this assumption is not strictly correct, and is particularly erroneous in the case of irregular protuberances into the airflow, such as those found on a longwall face. The errors arising from the assumptions may be avoided by using K-factors calculated by a newly devised method, described below, which takes into account the fundamental principles of aerodynamic drag analysis. This new technique has two advantages: first, it is flexible enough to model any longwall, regardless of equipment configuration; second, it employs terminology and equations familiar to those who perform mine ventilation analysis, using K-factors, for which ventilation engineers have an intuitive understanding, rather than drag coefficients. To provide guidance for development of a longwall drag model, data were taken on two modern longwalls operating in substantially different conditions. Pressure measurements at Mine B were made with 200-foot (61-m) sections of 1/8-in. (3-mm) diameter plastic tubing, attached to a Dwyer Magnehelic gauge. Pressure drops were measured in 200-foot increments down the face, and summed to give the drop for the entire face length. This technique was found to produce small, repeated errors because of the number of segments required to span the longwall. At Mine A this problem was avoided by using a single, continuous, plastic tube for the entire face length. The psychrometric properties of the air were measured for both Mines A and B. A calibrated, standard vane-anemometer was used to measure the airflow on both faces. Finally, numerous dimensions were measured on both faces, and face profile drawings were obtained to allow detailed evaluation of the face equipment geometry. From this information, accurate evaluations of the average wetted perimeter and average area of the longwall face airways were made. Since the airflow is not confined to inside the powered supports at all points along the face, a quadratically weighted average of the airflows measured at various stations along the face was calculated: [n2Qavg =Qi Ii / It(2)i=1] where [Q, avg = average airflow for analytical purposes, ft3/min (m3/sec); Q= airflow at station i, ft3/min (m3/sec); 1= length of segment represented by Q, ft (m); h= length of longwall face, ft (m): and n= number of quantity measurement stations.] The quadratic weighting scheme was chosen because the

Jan 1, 1992

By R. Sandrik

Northwestern Resources Co. (NWR) was established in 1972 as a wholly-owned subsidiary of Western Energy Company of Butte, Montana, to acquire, explore, develop, and produce energy resources outside the state of Montana. Western Energy is a coal mining company with successful operations in Montana and Wyoming. In 1974, NWR acquired its first lignite lease in Texas. NWR eventually acquired a large leasehold in central Texas, which was identified as having a high potential for future production. In 1979. NWR contracted to supply lignite to Utility Fuels, Inc. (UFI), a fuel affiliate of Houston Lighting and Power Company (HL&P). This project, together with leases held by UFI, became the Jewett Mine. Lignite from the Jewett Mine is used as fuel at the adjacent HL&P Limestone Electric Generating Station, at an annual rate of approximately 7.3 Gkg (eight (8) million tons) per year.

Jan 1, 1991

By E. Karampinos, P. Morissette

"INTRODUCTION Ground support is a critical element in maintaining the stability of mining drives in deep and high stress mines. In challenging ground conditions, it is necessary to continuously explore ground support strategies that can control the resulting large deformations. It is an objective of mining operations to optimize the ground support by selecting both appropriate systems and the time of installation of each reinforcement element. A successful ground support strategy will result in the use of a system that ensures both the structural and operational integrity of the excavations and mitigates the need for rehabilitation. Preliminary ground support design is often based on empirical observations and methods. Once a design is implemented, field trials, observations and in situ pull tests are used to fine tune or improve the design. Although not often employed during this process, numerical modelling can provide helpful insights on the impact of different ground support strategies. In this respect, it is possible to explore the use of multiple options before selecting the most promising ground support system for implementation in field trials. The challenges associated with the numerical modelling of rock support for mines have been described by Lorig and Varona (2013) and Potvin (2017). The employed numerical models should capture all potential failure modes of reinforcement over the mining sequence of the excavation. In particular, it is important to emulate the observed in situ ground support performance, as well as the influence of the installation sequence of the support. However, the time and expertise required for this type of modelling of ground support is not often available at mine sites. Even when the expertise is available it requires a major time and commitment of resources to set up, run and calibrate the sophisticated models capable of explicitly capturing the behavior of ground support. Rock reinforcement is an integral part of all ground support systems used in underground mines. Long flexible tendons can reinforce the rock mass deeper into the walls and create a thicker reinforced shell around the underground excavation. This paper focuses on the optimization of the cable bolting strategy in squeezing conditions at the LaRonde Mine by integrating the 3D distinct element method (DEM) in the design process. A calibrated numerical model is used to investigate a series of cable bolt configurations and provide recommendations for the ground support design."

Jan 1, 2018

By David B. McWhorter, John D. Nelson

INTRODUCTION The quantity of seepage that will be released from a tailings impoundment depends not only on the characteristics of the seepage control system, but also on the properties of the foundation soil or rock beneath the impoundment and the nature of the groundwater in the area. The interaction between various elements of the seepage control system and the influence the various characteristics of the site and impoundment have on seepage are the subject of this paper. The results of analyses are presented herein to indicate the nature and magnitude of the effect that the various factors will have on seep¬age losses. Analyses were conducted for a uranium mill tailings impoundment located in an area characteristic of many found in the western United States or Canada. A typical seepage control system consists of placement of either a clay or synthetic liner beneath the impoundment. In some cases an underdrain system may be placed on top of the liner to collect drainage from the tailings. The parameters that were varied in the analyses included those pertaining to the liner, underdrains and foundation strata. In general, it is shown that the seepage losses will vary in a complex manner depending on the interaction of the elements of the site and the seepage control system. As may be expected, the liner and underdrain systems have the most pronounced effect on controlling seepage. This paper deals with the quantity of seepage released from an impoundment However, the impact that seepage losses from an impoundment will have on the surrounding environment will depend on the rate at which contaminants will enter the groundwater and the nature of the groundwater flow itself. Consequently, when considering these results with regard to environmental impact they must be interpreted along with considerations of geochemical factors. MECHANICS OF SEEPAGE The mechanics of seepage and methods of analysis that were used will be discussed briefly herein. For a more detailed discussion the reader is referred elsewhere (McWhorter and Nelson, 1978, 1979, 1980). A general column through the impoundment was considered to be as shown in Fig. 1.

Jan 1, 1980

By R. H. Derammelaere

With renewed interest in coal slurry pipelines in China, Indonesia, Australia and Canada for electric generation, it appears worthwhile to update the relative economics of transporting coal by slurry pipeline. Three slurry pipeline technologies are evaluated for the commercial transportation of 3.0, 6.0, and 9.0 million tonnes per year (MMT A) example cases, over distances of 250 km, 500 km and 1000 km.

Jan 1, 1998

By James A. Commins

Accurate engineering predictions of energy needs for pollution control equipment used in surface mining operations is critically important to sound management selection of control alternatives. This paper will describe a procedure for evaluating two control alternatives with different energy needs. Three steps are involved: an analysis of the pertinent regulations, a determination of the size distribution of the particles being emitted, a calculation of the energy needs and costs of the candidate control systems as a function of these regulations and emission characteristics. The principal air pollutant to be controlled in surface mining operations is particulates, or dust, some of which is already on the material introduced into the primary crusher and other dust which is generated by the various steps in the subsequent processes. The requirement for control stems both from regulations concerning workers at the operating site, and the community surrounding the operations. In order to speak quantitatively about the need for control we will use regulations that pertain in Pennsylvania although it must be borne in mind that such regulations vary according to juristiction.

Jan 1, 1975

By J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The Sao Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in 1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000 ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

"There’s no fast way to add more than four miles of track, most of it underground, to the Sound Transit Link Light Rail system in the Seattle area. But increasingly busy traffic through a number of neighborhoods made it necessary. That’s the challenge a joint venture of several tunneling contractors faced when starting its portion of the $1.9 billion Northgate Link Extension in 2013, and the project is still keeping them busy three years later. Completion will mean just a 14-minute ride from Northgate to downtown for an extra 60,000 passengers by 2030. The transit lines will join 58 km (36 miles) of new and under-construction light rail lines running north, east and south from Seattle.Voters, tired of long commute times, approved the project, a key part of Seattle’s regional mass transit system, in 2008. The extension is part of a plan adopted by the Sound Transit board in 1996 to connect the region’s major activity centers. The Northgate project is meant to relieve one of the area’s most congested traffic areas by connecting the Northgate, Roosevelt and University District neighborhoods to existing routes including downtown Seattle and SeaTac airport.Sound Transit dedicated more than a quarter of the project’s estimated expense — $440 million -— to general contractor JCM Northlink LLC to handle the tunnel segment. JCM is a joint venture formed in 2013 between Jay Dee Contractors of Livonia, MI, Frank Coluccio Construction of Seattle, WA and Michels Corp. of Brownsville, WI. The contractors regularly collaborate on large-scale projects and brought experience working on a different section of the extension they completed in 2013.JCM project leaders knew immediately that the schedule would be demanding. They had to work around the clock, six days a week to meet deadlines. The extension runs through highly populated areas, meaning contractors had to follow strict city noise restrictions between 10 p.m. and 7 a.m. Plus, supervisors needed to manage the scheduling of nearly 250 employees to keep work running smoothly.“We had eight different operations and four different subcontractors trying to work in one tunnel,” said Chris Wood, JCM site project superintendent. “It’s important that we keep work linear. That’s the biggest challenge: keeping a path in and out so you can pour concrete, keep electricians and carpenters going, and accomplish everything else.”"

Jan 6, 2018

By George C. Toland

Tailings disposal has been a problem for the mining engineer since the beginning of the metal milling process. Disposal systems in common use have evolved as the most economic method for the disposal of an unwanted waste material within the disposal restrictions in force at the time of construction. As restrictions are constantly being expanded, the design requirements for tailings disposal systems are also being enlarged. However, proper design will always be to provide the most economic disposal system that will meet current safety and pollution requirements. This paper presents a brief description of some of the design features of tailings disposal systems in common use and presents specific design features of the gypsum tailings disposal pond at Kimberley, British Columbia, owned and operated by Cominco Ltd.

Jan 1, 1971

By Michael Fellows

Epidote is a common hydrothermal alteration product in many copper deposits of the southwestern United States. In many of these deposits epidote, along with calcite and chlorite, generally characterize a distal or halo propylitic alteration assemblage, but the mineral can occur within the central potassic alteration zone as well. Epidote is also a common alteration mineral in deposits formed in calcareous host rocks -- the skarn or pyrometasomatic ore bodies. Within the past 15 years, studies of the major and trace element composition of other alteration phases, principally biotite, associated with base metal ore deposits have demonstrated that some hydrothermal alteration minerals are compositional distinct from their igneous or metamorphic counterparts: However, the use of major and minor element content to identify and zero in on mineral¬ized areas does not appear to be very promising. Little work has been published upon the geochemistry of epidote from this standpoint and the results of my work suggest that a similar conclusion can be applied to epidote. My work (Fellows, 1976) suggests that epidote minerals in hydrothermal alteration suites from porphyry copper deposits in the southwestern United States are generally iron-rich rather than aluminum-rich. As a group, these alteration minerals differ compositionally from epidotes of regional metamorphic terrains. I ascribe these differences to the variations in the oxidation character of the respective environments. However, it appears as though the use of major element compositional variations of epidotes as an exploration tool is severely limited. Epidote is a complex calcium-aluminum silicate. Replacement of aluminum by ferric iron establishes a solid solution series between

Jan 1, 1977

By W. H. Langer

The U.S. Geological Survey (USGS) in cooperation with the New Mexico Bureau of Mines is conducting an assessment of mineral resources in the 36,800 km2 Mimbres Resource Area, southwestern New Mexico. Included in the assessment is a literature-based evaluation of sand and gravel that utilizes third party geologic information. The USGS has developed a method based on existing 1:500,000 scale geologic maps supplemented by remote sensing, statistical models, and point data such as test hole or pit records. The method defines the areal extent, quality, and quantity of aggregate.

Jan 1, 1996

By H. K. Lin

During slow-cooling crystallization of iron-making blast furnace slags, most rare-earth elements in the feed recrystallize as cerite-calcium while scandium and europium concentrate in a sheet-like "mineral". The mineralogy of this "mineral" is studied with one of the objectives being the extraction of the "mineral" from the slag for recovery of Sc and Eu. This "mineral" has been identified as one of the mica group minerals and can be named as rare-earth-bearing barium fluorophlogopite. The mineralogical characteristics of this "mineral" are investigated and discussed. This "mineral" can be effectively recovered from the slag by flotation with dodecylammonium acetate or a combination of dodecylammonium acetate and sodium oleate as a collector.

Jan 1, 1996

By Ethan Steward, Kyle Perry

The study investigates the effects of high-velocity impacts of common mine materials on a reinforced mine seal rated to 120 psi. It found that materials propelled during an underground explosion could generate enough stress to crack or damage seals, even with little visible damage. This highlights the need for careful evaluation of mine seals after any impact or high-pressure event.

Aug 1, 2023

By Donald D. Gullickson

The entire system is built around pre-designed and pre-engineered modules which are assembled to meet the metallurgical and production parameters of the project. The carbon vessels are the key to the flexibility of the system. The vessels are made of a coated mild steel, which allows the carbon vessels to be used in the adsorption, desorption and acid wash cycles. In the adsorption mode, the solution is pumped up-flow through four (4) vessels in series at 250 gpm fluidizing the carbon bed. When the carbon in the lead vessel is loaded, it is disconnected from the adsorption circuit via rubber hoses with quick-disconnect fittings. The second vessel is then made the lead vessel and a stripped carbon vessel is added to the end of the adsorption circuit.

Jan 1, 1998

By D. A. Karvonen

Although the economy in the Province of Saskatchewan has historically been agriculturally oriented, a major new source of wealth has been realized through natural resources such as petroleum and natural gas, coal and uranium and since the 1960's - potash. Potash or potassium chloride, in the form in which it is presently produced in Saskatchewan is used primarily as fertilizer, a source of potassium, one of three essential elements required for healthy plant growth with about 5 percent of production sold to the chemical industry for use in such products as soap and liquid detergent, glass and ceramics, textiles and some pharmaceuticals. Saskatchewan is estimated to have approximately 40 percent of known world potash reserves and its ten active mines account for some 25% of annual world production. The development of this resource was recognized to be important to the development of Saskathcewan. In an effort to guarantee a fair and lasting economic benefit to the Province of Saskatchewan the Potash Corporation of Saskatchewan (PCS) was created on February 4, 1975 through an Order-in-Council under the Crown Corporation's Act and later on April 1, 1976, the Potash Corporation Act provided for its continuation. PCS was given the mandate to acquire ownership of a significant portion of the potash mining capacity in Saskatchewan and to establish an organization capable of operating the facilities, marketing the product and conducting all of the other activities necessary for a successful corporation competing in the world potash industry.

Jan 1, 1983

By Gerald L. Dollinger, Joseph A. Roby, David Krauter, Kenneth Deering

Three high performance TBM's equipped with large diameter (483mm) disc cutters are currently operating in Norway. This paper summarizes the design philosophy, field performance and ongoing technical development of these cutters. Included are discussions of the early problems encountered with their usage and the solutions to these problems that have been developed. Also included are discussions of the penetration rates and cutter usages observed. From this data it is concluded that high performance TBM's with large diameter cutters can produce significant improvements in both overall performance and in cutter costs under hard rock conditions.

Jan 1, 1991