Search Documents

By Henrie Henson, Dan Burroughs, Shyi-Shyong Jiang

Jan 1, 1993

By Dennis K. Mortensen

The warm southwestern desert of Arizona is an ideal location for ASARCO's new Sacaton Unit. The climate of this arid region played a major role in the design considerations of the Unit's crushing and concentrating facilities. Low yearly rainfall and relatively high yearly temperatures are a combination that was taken advantage of when designing the surface facilities. The plantsite, located due west of the mine pit, is in an area originally covered with sparse desert vegetation, underlain to an average depth of 125 feet by desert alluvium. The entire plantsite area slopes gently to the southwest at approximately 1%. Ground conditions at the plantsite area were not acceptable for construction due to the collapsability of the wetted soil when under loaded conditions, Overburden from the pit area was used to form the foundation for the entire plantsite. This waste material, entirely devoid of rock, was placed and compacted to an elevation approximately 20 feet above the desert floor. Elevating the plantsite by filling with waste material not only provided an adequate construction foundation but also eliminated the possibility of flooding from run-off in the surrounding desert areas.

Jan 1, 1974

By Pedone Ezio Michele, Mohamed Dahir Holad

"The 4c segment is a part of the ""Oman National Railway Project” linking the mining area in the surroundings of Thumrait and the port of Salalah. It is 90 km long and the last 40 km stretch crosses a mountainous area near the city of Salalah. The project includes the excavation of a 33 km double and single bore tunnel and 10 km of safety tunnels. This mountainous area is a holiday destination for Omanis, thanks to its beautiful landscapes, especially in summer time due to the monsoon rains. The tunnelling design had to take into account both these environmental constraints and the limestone rock formations crossed, which are affected by significant karst features. Given the context, the conventional tunnelling method has been preferred. INTRODUCTION The Oman Railway Project (Fig. 1) covers the construction of approximately 2,150 km of railway line for freight and passenger transport which will connect together Oman’s main towns and industrial sites and it will form part of the Arabian Peninsula railway system “GCC Project”. The non-electrified double-track railway line must guarantee a speed of 220 km/h for passenger trains and 120 km/h for freight trains and must guarantee the transit of AAR (Association of American Railroad) H and D plates using clearance envelope according to AREMA (American Railway Engineering and Maintenance-of-Way Association) requirements. The design alignment must have maximum radiuses of curvature of 3,250m and a maximum gradient of 1.0%. The project is divided into 9 constructional and functional segments. •,Segment 4c will be constructed in the southern region of Oman, close to the border with Yemen, to connect the town of Thumrait with the Port of Salalah. •,Segment 4c will run through the Dhofar region and will be mainly used by the freight traffic which currently travels by road."

Jan 1, 2016

By Daniel N. Adams

The University Link project extends Seattle?s light rail from downtown to University of Washington (UW). It includes 5.0 kilometers (3.15 miles) of twin-bored, 6.4 meters (21 feet) excavated diameter tunnels, and two cut-and-cover stations. The Capitol Hill Station (CHS) requires an excavation 170.7 meters (560 feet) long, 22.6 meters (74 feet) wide, and 22.9 meters (75 feet) deep. The University of Washington Station (UWS) requires an excavation of about 238.4 meters (782 feet) long, 21.3 meters (70 feet) wide, and 33.5 meters (110 feet) deep. The project is within the glacially diverse soils of the Puget Sound region, below groundwater. This paper highlights major station and tunnel design elements, including the approach to support of excavation at both station boxes, and the site staging requirements.

Jan 1, 2008

By Hanguang Wu, V. Izaxon, Sukumar Bandopadhyay

This paper presents an analysis of the heat transfer process between the mine ventilation air and the frozen rockmass. The heat transfer model takes into account not only by the mutual change in air and rockmass temperatures, but also by the phase change of ice-water- ice. Based on the analysis presented here it is concluded that the mine thermal regime can be regulated by having the air enter the mine through mined-out excavations or development airways.

Jan 1, 1995

By N. D. Cristescu

An analysis of the interaction between a creeping rock and a yieldable lining is presented. The following cases are considered: an elastic lining, a lining made of circular shaft rings that may slide at their joints, a lining made of circular reinforced concrete panels with wooden compressible strips inserted between the longitudinal joints and a yieldable support that has a compressible broken-rock stratum between the support and plane rock. By formulating a mathematical model for the rock-lining interaction, one can optimize the sequence of excavation-lining application. To keep costs to a minimum, one can also choose the most appropriate lining for the corresponding rheological properties of the rock.

Jan 1, 1997

By N. D. Cristescu

The aim of the present paper is to show how a mathematical modeling of a creeping rock and that of an yieldable lining can allow us to obtain an optimization of the lining design and generally of the whole procedure and sequence of excavation-lining application. We follow the procedure presented by Cristescu (1989) Chap. 13, and Cristescu et al.(1987); for some other approaches see the literature mentioned, for instance, by Ladanyi and Gill (1988). We have in mind to describe the creep of the rock, i.e. the tendency of the tunnel to close in time, and to take into account that the lining itself may be deforming, i.e. possesses some rheological behavior. We start from the well known fact that "intelligent" lining, which are yielding to the pressure of the rock, may be much more successful in supporting creeping rocks than excessively strong, badly designed supports which are unable to resist to pressure of the rock, though these are oversized supports (too strong, too stiff, installed too early, etc.). In order to optimize the lining to be used for a certain rock, it is absolutely necessary to study in the laboratory the main mechanical properties of that specific rock and to formulate for it a reasonably simple mathematical model. Standard triaxial test results are quite enough to determine the model for the rock, combined with some creep tests which have to reveal the long-term behavior of rock (the so-called rheological model). What concerns the lining, we consider several kinds of linings existing today, for which a mathematical model was also formulated. One shows which is the interaction between the creeping rock? and the yielding lining and how can it be formulated in mathematical terms. Once written in mathematical terms, an optimization of the lining design and that of the excavation layout and support application sequence is possible. We will try to make the exposure as simple as possible, avoiding details and having in mind to give only a sketch of the problem, while the mathematical details could be worked out quite easy.

Jan 1, 1994

By D. Marsh

The feasibility study for the Grasberg Block Cave mine, finalized in May 2008, indicated a production capacity of 160,000 tonnes per day. A rail haulage system was an integral part of the mine design. This paper describes the simulation process used in optimizing the design and discusses the key factors and variables that impact the capacity of the system. The final recommendations for the haulage level layout and associated equipment are also included.

Jan 1, 2010

By Marian W. Otrebski, Julian A. Korneck

Long distance, overland conveyors require significant capital outlay of which up to 70% may be contributed to the cost of belting. Significant savings may be achieved by identifying possible risk areas and applying modern technology methods to reduce or eliminate risk. Recently, Sasol Coal commissioned an overland belt conveyor system comprising three belt conveyors of 7 km, 5 km and 4.5 km in length. These were designed and constructed taking the above into consideration. Contained in the paper are the belt conveyor system requirements, designing assumptions and methods applied in the designing process as well as ways and means to eliminate or at least reduce risks.

Jan 1, 1998

By T. M. Barczak, S. C. Tadolini

Reduction in the recovery time required and improvements in safety during a longwall face move have compelled coal mine operators to examine and use pre-driven longwall recovery rooms. The recovery entry is developed at the longwall stop position and supported ahead of time so that the required combinations of standing and internal sup-ports can be installed before the longwall face approaches. A calibrated three-dimensional finite element model, developed in conjunction with an underground test area, provided the critical components and design principals for a comprehensive parametric study. The study indicates that vertical, horizontal, and shear stresses concentrated on the outby abutment pillar corner of the recovery room resulting in deformations in the immediate roof above the primary roof support anchorage level. The results of the numerical model and field site observations indicated that the combination of the internal bolting system and the standing concrete supports are critical for the successful and safe extraction of the longwall equipment. Cable supports installed at and angle over the pillars can help stabilize the disturbed zone above the adjacent fender and outby pillars, however; standing supports are required in most sedimentary roof conditions to increase stability and assure a safe longwall extraction.

Jan 1, 2004

By Werner Burger

The last decade has witnessed a rapid development and application of slurry and EPB type tunnel boring machines. Both soft ground types are able to excavate tunnels in unstable ground conditions below the water table with positive face support. The most significant component of the excavation process is the cutterhead and tool con-figuration were the excavation and face support meets the geological challenge. The TBM downstream processes cannot take place unless the cutterhead and tools effectively do their job. This paper will review the current state of the art design for both slurry and EPB cutterheads and highlight both common as well as geological specific design features.

Jan 1, 2007

By Ian S. Ross

The emphasis in this paper is focussed on dry bulk car go or the same cargo converted to slurry form for ease of handling. It is this type of cargo which is of primary interest to the mining industry whose products it represents to a large extent. The design problems associated with the handling of liquid bulk and of unitized cargo are sufficiently different to be treated separately. This paper then will consider the port handling facilities of dry bulk commodities as part of a system consisting of (1) the movement of products to the port area, (2) the movement of products out of the port area and (3) the handling of products within the port area itself. Expanding within these three components of the total transportation system, the paper will discuss the various difficulties encountered concerning the mode of transport into the port area and the method of handling product from transport to stockpile. Secondly, and before discussing the port area itself and in order to complete the conditions under which the port must operate, the movement of products out of the port area will be covered dealing with such items as the accommodation of the ship, problem associated with the very large ships, optimum berthing arrangements and the need to consider the various costs associated with the vessel. Finally the paper will review within the port or interface area such items as stockpiles, method of recovery, inventory control and an outline of the common design difficulties encountered. In all cases the relative influence on the total transportation costs of each of these dry bulk transportation system components will be considered.

Jan 1, 1972

By Birger Schmidt

The design of underground nuclear waste disposal facilities poses new problems related to the requirement of long term safety against radionuclide migration. The degree and effects of rock disturbance caused by construction and by the long term thermal effects from the hot waste must be predicted with confidence. Computer modeling can, to an extent, be verified by accelerated near-surface tests. Credible extrapolation to deep, long-term conditions requires successful near-surface modeling verification, proper characterization of near-surface and deep rocks, and successful determination of in-situ stresses. Excavation induced disturbance may be assessed primarily by empirical evidence.

Jan 1, 1981

By D. G. Mirakovski, B. Krstev

The paper presents models of auxiliary ventilation systems with leaky ducts and algorithms for calculations of pressure loss, air leakage, and volume flow ratio and pressure fans. Two basic models are discussed: 1st model for a duct with leakage through the flange joints; 2nd model for a duct with an equivalent longitudinal aperture. The present analytical system has been successfully applied to developing of computer software named DAVentS. A. sample problem is used to illustrate efficiency and accuracy of DAVents software in solving most common problems in process of designing AVS.

Jan 1, 2002

By P. D. Pack, E. H. Skinner

During design of a 550-foot rectangular shaft in alluvium, lateral support within the excavation was an anticipated construction problem. Actual experience showed that the nearly 9 x 14 foot excavation required no lateral support. A strain measurement program con- current with construction and for a 9-month period following completion of the shaft detected only minor strains. Shaft design included consideration of available geological information. Site exploration included a 754-foot drill hole, cored at selected intervals, and a suite of geophysical well logs. Generalized physical properties of the alluvium were developed from laboratory core testing. An elasto-plastic, finite element computer program (DAHLKE) developed by the Spokane Mining Research Center U.S. Bureau of Mines, has been recently used to analyze the behavior of the alluvium around the shaft. Analysis showed that yielding first develops in the shaft corners and progressively expands into the wall zones around the shaft as loading increases. Gradual growth of a plastic zone progressed outward from the excavation boundary at increasing loads but had limited extent and was surrounded at all stress levels by an infinite elastic zone. This design review, aided by computer analysis, confirmed that the shaft would have been considered theoretically stable as designed.

Jan 1, 1977

By Samer Sadek, David I. Smith, Wai-shing Lee, Jeffrey L. Rice, Avelino Alonso

INTRODUCTION East Side Access (ESA) Contract CQ028 is located in the New York City Borough of Queens. The contract involves construction of a 230-meter (760-foot) long open-cut excavation with a permanent deck supporting Amtrak yard tracks over a semi-circular TBM launch wall on the east end, and the 36.5-meter (120-foot) long Northern Blvd. Crossing on the west end. The Northern Boulevard Crossing will be mined under an existing New York City Transit (NYCT) five-track subway tunnel; Northern Boulevard, a heavily traveled five-lane truck route; and an existing NYCT three-track elevated line; connecting to an existing open-cut shaft adjacent to the existing 63rd Street Tunnel bellmouth. When completed, Contract CQ028 will provide access for future Manhattan and Queens tunnel contracts. The footprint of the open-cut was determined by the geometric requirements of the future Plaza Interlocking facility to be constructed within in another future ESA contract. See Figure 1. This paper discusses design risk mitigations for the key elements of the contract, namely the Northern Blvd. Crossing and the semi-circular TBM Launch Wall. PROJECT OVERVIEW The Metropolitan Transportation Authority Capital Construction Company—East Side Access Project for the Long Island Rail Road will provide Long Island commuters with direct access to Manhattan’s East Side via a new rail line between the Harold Interlocking in Queens and Grand Central Terminal in Manhattan. The project connects the unused lower level of the existing tunnel under the East River at 63rd Street to new connecting tunnels in Queens and Manhattan. Contract CQ028 Scope and Construction Schedule This contract consists of the excavation of an open-cut from the east side of Northern Boulevard, through an existing MTA-owned rail yard and into the western limits of Amtrak’s Sunnyside Yard. The contract will connect to a completed open-cut

Jan 1, 2007

By G. R. O?Neil

The justification for a "ligand- selective' approach to fine mineral beneficiation via flocculation is established initially. Special emphasis is placed upon the need to identify non-selective, interfering and complicating adsorption effects. Specific strategies directed towards the design and synthesis of complementary selective flocculants are detailed using a number of different polymers and chelating agents as examples. In this regard, the affinity of polymer-bound ligands for metallic cations, ligand concentration, possible modes of attachment, the application of spaced-out ligands and other considerations in the preparation of selective flocculants are highlighted.

Jan 1, 1983

By Scott G. Britton

Up to now, the hands-on approach to construction has been stressed. This chapter reviews the basic tools available for construction design and monitoring of a construction project. It is divided into three discussions, all under the general title of computer aids, since the trend for using these tools-is via the computer. In the context of our discussions, the focus for computer aids will be on the use of evaluation and analysis techniques for coal mine construction applications, including mainframe programs, CPM techniques, as well as mini and microcomputer applications. Although the presentation of material in this chapter may be detailed at times, by no means does it cover the entire field of computer applications for design or project scheduling and monitoring. It is only an attempt to illustrate the possibilities that are available to construction and mine engineers. Interested persons can pursue computer applications for coal mining by reviewing Computer Methods for the 80's. by Alfred Weiss, editor, published by SME-AIME.

Jan 1, 1983

The design of solvent extraction plants has been generally based on the assumption of steady operating conditions in both the settler and the mixer units. However, recent experience in both large and small plants has shown this not to be the case. Mixer transients include start up aqueous locking and partial phase separation in secondary mixers, which both lead to reduced plant capacity or overflow of upstream mixers. Analysis of the hydraulic pressure profiles has generated new design methods to eliminate the effects of the partial or complete phase separation. Changes to the method of specification and selection of primary and secondary mixers have been made to eliminate the onset of partial separation during operation. The observation of settler operation has shown that it is also a dynamic process, even under "steady-state" conditions. Four transient phenomena have been identified that lead to internal circulating flows, poor disengagement of fine secondary haze and erratic and high entrainment levels in the discharges. A, first approximation analysis has shown that there are significant pressure differentials within settlers, and these change along the length and with the phase separation rates. A technique to control the effects of these transients was developed that allows plant performance to be improved beyond "standard" expectations. The design and selection of the settler internals is described. Key words: Solvent extraction, Mixer-settlers, Phase separation, Entrainment, Mixer transients

Jan 1, 2003

By G. Miller

The design of solvent extraction plants has been generally based on the assumption of steady operating conditions in both the settler and the mixers. Recent experience with both large and small plants has shown that this is not the case. Mixer transients include start up aqueous locking and partial phase separation in secondary mixers. Both of these lead to either reduced plant capacity or overflow of upstream mixers. Analysis of the hydraulic pressure profiles has generated new design methods to eliminate the effects of the partial or complete phase separation. Further, changes to the method of specification and selection of both primary and secondary mixers have been made to eliminate the onset of partial separation during operation. Observation of settler operation has shown that it is also a dynamic process, even under ‘steady state’ conditions. Four different transient phenomena have been identified that lead to internal circulating flows, poor disengagement of fine secondary haze, and erratic and high entrainment levels in the discharges. A first approximation analysis has shown that there are significant pressure differentials within settlers and these change along the length and with phase separation rates. A technique to control the effects of these transients has been developed which allows plant performance to be improved beyond ‘standard’ expectations. The design and selection of the settler internals is described.

Jan 1, 2001