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By S. A. G. Poppen

The lining of a mine shaft is one of the most important considerations in the planning and operation of an underground mine. Generally, the function of a shaft lining is to preserve the shaft opening in a manner compatible with the expected mine life and -the other shaft operations. Where shafts are the only means of surface access in a mine, they also serve a critical function for the safety of the entire underground operation. Routine repairs and maintenance work on the shaft linings are only possible in stable strata with only minor interruptions to the shaft operations.

Jan 1, 1988

By W. R. Dengler

INTRODUCTION Shaft sinking represents a relatively small proportion of the activities involved in mine development. Because of this limited utilization, shaft sinking has been one of the most difficult functions to mechanize. Although shaft machines (muckers) were introduced more than 30 years ago, the first machines were low-capacity units, and machines of this type did not gain wide acceptance by the mining industry until the late 1950s. However, the increasing depth of underground mines and the es¬calating costs of labor have increased the benefits obtain¬able from high-speed shaft sinking. The result has been a growing need for high-capacity shaft machines. Most of the machines available at the present time have been developed by modifying existing equipment to increase the payload capacity and performance. AVAILABLE SHAFT MACHINES In general, shaft machines may be classified accord¬ing to the types of digging mechanisms and the mecha¬nisms of operation. The available digging mechanisms include clamshells, cactus grabs, front-end buckets, and backhoes. The mechanisms of operation can be classified as either pneumatic or hydraulic. Selection Criteria For efficient operation, the primary consideration in selecting a shaft machine is its capacity. The minimum capacity of the machine should match the capacity of the hoisting system at the ultimate depth of the shaft. In many cases, two machines may be needed to obtain a sufficient mucking capacity. The shaft dimensions and configuration often dictate the type of machine that may be utilized; for example, an overshot loader does not work well in a circular shaft that has a diameter of less than 5.5 m (18 ft). Similarly, a single Cryderman mucker is not suitable for a large-diameter shaft, nor is it applicable where very high sinking buckets are to be used. Other factors for consideration include the degree of material fragmentation, the abrasiveness of the rock, and the amount of ground water that is inter¬sected. Machine Descriptions Riddell Mucker: The Riddell mucker, illustrated in Fig. 1, was first introduced in 1948. This is one of the most common shaft machines in the medium-capacity range. The Riddell mucker consists of a hoisting and traveling mechanism that operates a clamshell suspended on cables. The early machines operated with a 0.3 m3 (10 cu ft) clamshell and had an hourly capacity of approximately 27 t (30 st). This type of shaft machine has gained wide acceptance throughout North America. Essentially, the Riddell mucker consists of standard components, such as the pneumatic tugger hoists that operate the clamshell. The carriage is suspended on rails that also serve as the blasting set, located immediately below the shaft timbers. To effectively position the clam¬shell in the shaft, the operator controls the carriage travel by means of wheels that are driven by a pneu¬matic motor. The Riddell mucker most commonly is used in rec¬tangular timbered shafts. However, some units have been installed with circular rails, allowing them to work in circular concrete-lined shafts. A popular practice with many Riddell muckers is to increase the capacity through the use of larger clamshells, often ranging up to 0.76 m3 (1.0 cu yd), in conjunction with more powerful tugger hoists. In some large rectangular shafts, two Riddell units have been used side by side to achieve a sufficient capacity. Cryderman Mucker: The Cryderman mucker, illus¬trated in Fig. 2, is another common shaft machine in the low- to medium-capacity range. Developed in the early 1950s, it also has gained wide acceptance throughout North America. Equipped with a 0.3 m3 (10 cu ft) bucket, the Cryderman mucker has an hourly capacity of approximately 23 t (25 st). The Cryderman mucker is operated entirely by means of pneumatic cylinders and a pneumatic telescopic boom. The boom is suspended from a sectional frame¬work that is usually located at one end of the shaft. The framework or headframe can be suspended from an independent hoisting system located either on the sur¬face or in the shaft. In large shafts of either rectangular

Jan 1, 1982

By D. W. Alexander

In 1993, CONSOL began investigating new methods of permanently filling coal mine shafts, which after ventilation is stopped, may contain a potentially hazardous atmosphere. Fill materials such as fly ash/cement can be pumped, are non-combustible and non-incendiary but tend to flow into the mine entries. A non-flowable mixture has been developed that minimizes the volume of fill used. The paper presents our recent shaft filling experience including fly ash material properties, mix designs, field problems, placement success, and gas testing techniques.

Jan 1, 1996

By J. W. MacDonald

Two coal mine shafts recently completed in Franklin County, Ill., afford experience and accomplishment to warrant review, These shafts provide access to a tract with a potential recovery of one hundred million tons. This work provided the initial sinking by other than a contractor's organization since 1918. Four additional shafts required during the interim were sunk under contract arrangement with others. Supervisory contact and inspection afforded experience to govern planning and conduct of the recent work.

Jan 1, 1960

By D. R. McMullin

The purpose of this paper is to provide a method for mine planners and engineers to evaluate on a conceptual basis if a shaft or a ramp is most suited for their particular underground access requirements. Mine planners and engineers are often raced with the decision of choosing which method of underground access is best suited for their particular requirement. Underground access can be provided by a shaft, ramp, adit, or slope for either exploration and/or actual production operations. This paper will focus on the construction cost and schedule differences between sinking a shaft and excavating a ramp which are currently the most typical access alternatives used in the western United States. It would be wrong to state that one method is superior to the other in every case. There are many variables to be addressed, and the degree of sensitivity of each of them will eventually dictate which method is the most suited to the particular circumstances. This paper compares the construction cost and schedule or sinking a shaft to excavating a ramp at different depths given different ground and hydrological conditions. This comparison provides mine planners with "rules or thumb" that may be applied to the access selection process.

Jan 1, 1994

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By Andreas Prucker

The Greater Vancouver Water District (GVWD) is currently constructing the largest water treatment plant in Canada. As part of this treatment scheme twin water transfer tunnels are being constructed. Work commenced with the 11 m diameter, 185 m deep Seymour Shaft which was excavated by drill and blast using a mobile crane for hoisting. The Seymour Shaft is the first large diameter shaft that has been sunk in Western Canada in recent years. The operational aspects associated with the hoisting, the drill-blast-support cycle and water control in the shaft are the focus of this paper.

Jan 1, 2008

By P. J. L. Nel

The paper describes several successful concepts used in the sinking of shafts on the Elandsrand Gold Mine. The concepts enabled the shaft sinking time to be reduced as well as the period in which development would normally take place to establish initial ore reserves.

Jan 1, 1981

By Gerald G. Griswold, Allan G. Provost

"To Sink or Not to Sink"; this play on the Bard's words sums up the considerations and problems that face the owner on every potential shaft sinking project. The growing demand for access into the earth is pressing construction into new areas and to greater depths. The following discussion will entertain some of the effects of these new and unknown aspects upon the approach to designing and sinking of deep shafts. We will also look at the current shortages of equipment, materials and skilled manpower, and their effect upon the planning and sinking of shafts. Particular emphasis will be placed upon equipment selection, and we will discuss how economics, while always a prime consideration, is now, more than ever, both an incentive and a detriment to the industry. FUTURE CONSIDERATIONS Shaft construction is assuming ever increasing importance both in mining and civil endeavors. The rapid depletion of near surface mineral reserves is requiring the mining industry to look deeper into the earth for new sources. These greater depths increase the exposure to unfavorable geological conditions; heavier ground, high water pressures, and high temperature. South African gold mines have now reached depths of 12, 000 feet, where the rock temperature is 1380 and water bursts from the fissures. In North America depths to 7, 500 feet have been sunk, but deep shafts are still generally considered to be those of

Jan 1, 1974

By F. Dieu, C. Laughton

CERN, the European Laboratory for Particle Physics, is, at present, constructing an underground tunnel and cavern network to house a Large Electron Positron (LEP) colliding beam machine. This paper describes the techniques adopted to permit the excavation and temporary support of the access shafts through a series of glacial moraines, at depths of up to 80 m, to reach the bed-rock. Owing to the presence of superficial and deep water-tables, the variable nature of the moraine deposits and, above all, the tight work schedule, a combination of diaphragm walling and ground freezing was employed.

Jan 1, 1987

By Peter White

The Hemlo Gold District, located on the north shore of Lake Superior, was discovered in 1981 and will become one of the largest gold mining camps in Canada. Three major Canadian mining companies are presently developing large orebodies and are scheduled to commence production at various times through 1985 and 1986. This paper describes the types of shaft sinking equipment and technology being used by contractors in constructing the required shafts to depths below 1000 metres. The principal shaft design criteria, types of shaft sinking machinery and relevant manpower allocations are discussed.

Jan 1, 1985

By A. J. Stewart, M. Guay, J. W. Critchfield, A. P. Hoddeson

The MetroWest Water Supply Tunnel project includes three main work shafts, excavated primarily in rock. Shaft L is 9.8 m (32 ft) diameter and 124.1 m (407 ft)deep. Shaft E is 7.0 by 12.8 m (23 by 42 ft) and 91.4 m (300 ft) deep. Shaft 5A is 7.9m (26 ft) diameter and 72.5 m (238 ft) deep. Construction methods are compared and contrasted. Lessons learned involve a differing site condition in soil overburden, contractor-proposed modifications, and remedial slurry wall work. Other aspects discussed include noise and vibration control, groundwater inflow, water treatment, muck handling and contract administration issues.

Jan 1, 1999

By John W. Wilson

INTRODUCTION In the past, the cost and time required for the construction of shafts has played an important part in the planning of underground mines. For reasons that are discussed later, the economics and technology of shaft construction in the future can be expected to play an even greater role in the planning of new mines and the operation of existing mines. Indeed, the very feasibility of a proposed mining venture may depend on the cost and timing of the shaft requirements. The most commonly used shaft sinking methods used today for excavating vertical shafts are discussed and the need for new technology and methods emphasized. In one study by the U. S. Bureau of Mines, it was reported that the coal industry in the United States alone could require 170 to 190 new shafts per year on the basis of doubling current production by the mid 1980's or 70 to 90 shafts on a more moderate coal production expansion program. This study concluded that the attainment of the required number of shafts would be unlikely with the present shaft sinking resources and costs. In order to meet the requirements for shafts in the United States coal and metal mining industries, more efficient and speedier shaft construction methods will be necessary. Current shaft sinking methods are, in the main, labor intensive, and it is noteworthy that it is becoming increasingly difficult to attract the work force required to sink shafts conventionally. Because of this situation, some attempts at mechanization have been made to compensate for this ever-increasing scarcity of trained

Jan 1, 1976

Planning the primary development of a mineral deposit usually is done only once during the life of a mine. As a consequence, not optimizing the primary development of a mineral deposit can cause disadvantages over the whole life of a mine and can lead to higher costs. As a contribution to an improved primary development design procedure beyond the already existing work a study of the identification and quantification of the influence of parameters on primary development based on operational data from working mining operations has been completed. Based upon such a quantification of the influence of parameters a sequenced decision model was developed, that enables to develop an initial concept for the design of the accesses from the surface based upon a few critical parameters. Such a model will not replace detailed planning work within a feasibility study, but it is intended to reduce the amount of planning efforts at an early project stage through providing information what are most likely economic solutions, based on simple rules.

Jan 1, 1997

By William C. Paschen

Damen Avenue to Roosevelt Road, the Tunnel and Reservoir Plan (TARP), a Deep Tunnel Project for the Metropolitan Sanitary District of Greater Chicago consists of 25,189 lin. ft. of 32 ft. tunnel with 1 ft. 0 in. concrete liner throughout. The 17,100 ft. main tunnel connects at both ends with two other Deep Tunnel contracts. A branch tunnel connecting to the mainstream tunnel, commences approximately 4,140 ft. from the construction shaft and runs 8,089 ft. south and terminates at the Racine Avenue Pumping Station. Shaft work consists of one 28 ft. 6 in. diameter construction shaft, one 3 ft. 6 in. diameter access shaft and 25 drop shafts-four of which have vent shafts. The drop shafts vary in diameter from 4 ft. 0 in. to 17 ft. 0 in. All shafts vary in depth to invert from 225 ft. to 235 ft. Work has been underway for 16 months and as of this writing the construction shaft and access shaft are complete. Seven shafts have been excavated and concreting operations have started in four of them. The starter tunnel is complete, the mining machine has mined 250 lin. ft. and the muck removal system is in full operation. The contractor for the project is a joint venture of Paschen/Morrison-Knudsen/Kenny. Paschen Contractors, Inc., Chicago, Illinois is the sponsor. The total contract amount is $107,837,300.00.

Jan 1, 1979

By P. Bevilacqua, G. Ferrara, M. C. Williams, T. P. Meloy

Tabling is an old environmentally friendly separation unit operation. This paper models shaking tables and explores the action and design of riffles on shaking tables. By reassessing riffle shape and riffle patterns, significant improvements in tabling performance appear feasible. While table sales appear at their nadir, a high-tech environmentally friendly table may have a significant market in the coming decade. Riffles on a shaking table impact particle separation. Particles are affected by riffles and their exit position on the table is dramatically changed, Riffle shape determines how much the riffle will influence a given material. Moreover, riffle patterns influence the concentration of a given material and its exit points on a table. This effect of riffle placement and design is modeled in a spreadsheet. Major performance and separation improvements may he expected by improved table design. Two physical laws of tabling have been derived. These laws aid in the design of sophisticated high-tech tables.

Jan 1, 1995

By T. P. Meloy

Riffles on a shaking table have a major effect on particle separation. This effect is modeled in a spreadsheet.

Jan 1, 1993

By Peter Zhang, Daniel Su, Mark Van Dyke, Heather Dougherty

The integrity of shale gas wells in longwall chain pillars under the influence of longwall mining is a safety concern for both coal and gas operators. Previous modeling studies of gas wells in longwall pillars have shown that a FLAC3D model can predict longwall-induced stresses and deformations in gas well casings with reasonable accuracy. The predicted casing deformations can be verified by multi-finger caliper survey. This study concerns the influence of longwall mining on eight shale gas wells in a shale gas well pad located in the chain pillars between two adjacent longwall panels under 1,030 feet of cover. FLAC3D modeling was performed to predict longwall-induced deformations in gas well casings based on site-specific mining and geological conditions. Small deformations less than 0.5 in were predicted in the intermediate casing above 600 ft depth, and very small casing deformations less than 0.15 in were predicted below 600 ft due to high abutment pressure and high frictional resistance along the weak bedding interfaces. After the first panel was mined, a 56-arm caliper survey was performed on one of the wells to measure the longwall-induced casing deformations in the intermediate casing. The predicted casing deformations were then compared with the measured deformations, which indicated that the prediction was generally in good agreement with the measurement in terms of deformation locations and magnitudes. Findings from this study provide valuable information not only for stability assessment of shale gas wells in longwall chain pillars but also for developing engineering guidelines to preserve casing integrity through adequate pillar and casing design.

By Judith M. Ballantyne

Carlin-type. disseminated, sediment-hosted gold deposits can be better described as hydrocarbon-associated gold deposits. A new genetic model for these deposits involves the intrusion of one or more small bodies of magma into a shallow hydrocarbon reservoir or ma of hydrocarbonenriched rocks, imposing a convecting geothermal system on the local groundwater. Pyrite, commonly associated with the organic material, provides a substrate for deposition of gold and other trace elements in an environment rich in dissolved sulfide. Both diagenetic and hydrothermal pyrite may act as gold depositional sites. Thermal cracking of hydrocarbons, catalyzed by illite, subsequently generates an oxidizing environment by depleting hydrogen. As oxidation increases, arsenic sulfide minerals and barite m stabiied at first. Increasing hydrogen depletion converts sulfide to sulfate, generating acid oxidizing conditions which: alter pyrite to hematite; continue the deposition of sulfates; and ultimately develop late stage acid-sulfate assemblages containing minerals such as kaolinite. alunite. and jarosite. Gold released from the oxidizing pyrite is redeposited as free gold, and pehaps remobilized.

Jan 1, 1988