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By Jack G. Pippenger

The Coteau Properties Co.'s Freedom Mine is a surface lignite mine that uses large draglines, trucks and shovels, tractor-scrapers and bulldozers to uncover a single coal seam. In 1989, a work order system was instituted to record data by equipment type, cost, productivity and distance. The system was also used to provide historical information to plan the most efficient and economic use of each equipment type in the mining operation. The Coteau Properties Co. is a wholly owned subsidiary of The North American Coal Corp. The company was formed in 1972 to supply lignite from its Beulah-Hazen coal reserve to a coal gasification project and an electrical generating facility located near Beulah, ND. The reserve consists of a single coal seam between 3 and 7 m (10 to 23 ft) thick. The overburden above the coal is predominately glacial tills and clays and ranges from 6 m (20 ft) to more than 60 m (200 ft) thick.

Jan 1, 1994

By Tim Brick, Peter Jewell, Stephen Thompson, Simon Morgan

The $980m (€750m) Dublin Port Tunnel, Europe’s biggest urban highway tunnel project, was opened in December 2006. The culmination of this immense scheme is set to transform the environment, mobility and road safety of Ireland’s capital city. This paper summarizes the key aspects of a project linking both sequential and parallel construction of individual tunnels and describes various approaches to bored, mined and pre-support cut-and-cover tunneling in a wide variety of ground types and depth of cover. Examples of innovative approaches to deal with structural and geotechnical problems while maintaining full operation of both road and rail traffic and the integrity of properties in a dense urban corridor are described.

Jan 1, 2007

By Jerry Wang, Greg Bold, Mahmood Khwaja, Rebecca Caldon, William Simcoe

Phase III and Phase IV of the Beaver Creek Clean River Project, Albany, NY, includes microtunnel construction of 2,320 feet of 48-inch/36-inch internal diameter (ID) conveyance pipe and a 525 foot long 9.5-ft horseshoe shape roadheader excavated tunnel. Notable challenges were encountered during the construction including mixed face tunnel conditions, undocumented existing fill ground conditions that resulted in settlement during shaft construction, and unstable tunnel face conditions. This paper discusses several of the key challenges encountered during construction and selected solutions to construction sequencing and methodology to successfully complete Phase III and Phase IV of the Beaver Creek Clean River Project.

Dec 1, 2022

By Zhenqi Cai, Mike Lichte, Kimberly Kennedy

The Ohio River Tunnel is the first of three combined sewer overflow tunnels to be constructed under Allegheny County Sanitary Authority's Clean Water Plan. The project consists of a total of approximately 5.5 miles of 18-ft and 14-ft finished diameter, segmentally lined deep rock tunnels and smaller diameter dewater and flow connector tunnels, as well as 8 deep flow drop and access shafts varying from 25-ft to 70-ft in finished diameter and 130-ft to 170-ft in depth. This paper describes the project components and the primary engineering challenges faced during design, including tunnel alignments and shaft site optimization with tight right-of-way constraints and multiple railroad and highway crossings. Assessment of tunneling methodology as well as tunnel and shaft designs and constructability included overcoming 5-bar hydrostatic pressure, abrasive bedrock, and the selection of the appropriate support of excavation systems in high-permeability alluvial soils adjacent to the Ohio River.

Jun 23, 2024

By G. Balletto, C. Furcas

"The mineral raw materials industry is a key-component of the Gross Domestic Product of industrialised economies, closely related to both the building and the industrial sectors. Despite this, at local level mining and quarrying are associated with both irreversible environmental damage and several visual alterations affecting the natural landscape. In this sense, SIA (Social Impact Assessment) has become a strategic tool that can not only improve the prediction but also the assessment of the social impact by involving the local communities in a participatory process. Taking into account the SIA experience, together with the examination of some relevant international case studies, it is possible to draw up a list of good practices for mining project management, from exploration through to closure and beyond, with quarry restoration. Such good practices will complement the existing studies, focusing on environmental issues, with the social issues arisen considered in SIA application."

Jan 1, 2011

By Hiroyuki Tamaru, Futoshi Kusumoto, Kosuke Tanimura, Atsuyuki Kimura

"SUMMARY The Hachinoshiri tunnel is a 2,469 m long two-lane road tunnel on the Chubu-Odan Expressway. Since more than 70% of the total tunnel length consists of low strength rock masses the competence factor of which is less than 1.0, it is expected that a self standing span cannot be achievable because of no ground arch to be established. The tunnel was thus designed with tunnel support patterns forming multi-arc early ring closure that can develop the load-carrying capacity estimated from the exerted earth pressure, Po, which can result from the competence factor, cf. The tunnel support pattern was selected based on the competence factor at tunnel face, then the subsequent tunnel support patterns were determined with reference to the monitoring data. The tunnel construction adopted full-face excavation accompanied by early ring closure using a 330 kW road header. The proposed construction methods at this tunnel site have turned out ensuring tunnelling in massive squeezing rock, so that they can be verified as reasonable tunnelling technologies, clarifying the relationship between the characteristics of the mechanical behaviour of the tunnel and its design parameters. INTRODUCTION The presence of highly weathered mudstone having the competence factor less than 1.0 where the tunnel became unstable with the early ring closure having the distance to early ring closure, Lf, of 6 meters, resulting in difficulty in maintaining the inner section of the tunnel, prompted a substantial amount of high strength double support and replacing of the tunnel support (Sato et al., 2015). Based on the mechanical characteristics learned from the construction, the mechanical stability of multi-arc tunnels was investigated using 3D FDM analyses with respect to the ratio of the radius for early ring closure, r3/r1, and the distance to early ring closure, Lf, so that tunnel support patterns for early ring closure can be established in terms of the competence factor, of, which was employed for a 725 m long section. Consequently the tunnel support patterns for early ring closure which can be determined from the competence factor became applicable to tunnel construction. The relationship between the characteristics of the mechanical behaviour of the tunnel and its mechanical parameters was also clarified. The early ring closure method adopted ensured tunnelling in massive squeezing rock, verifying its effectiveness in stabilizing the tunnel."

Jan 1, 2016

By James Humphrey

There is a natural resistance to change in any form. When it comes to implementing a game-changing technology like autonomous haulage on an operating mine site, the resistance can at times appear insurmountable. Whether based on real information or misguided preconceptions, it?s essential that we don?t underestimate the effort it will take to overcome this resistance, while clearly recognizing when it?s worth the effort. These realizations did not happen overnight for sites where autonomous haulage has been implemented. Nor did they happen overnight for manufacturers of autonomous mining equipment. Caterpillar, for example, began building toward autonomy more than 30 years ago and had a truck operating in the mid-1990s. Lessons learned during those early years led to the realization that there was much more to be learned ? not just about the machines themselves, but about the systems and knowledge that must be in place for a successful implementation. Working closely with customers, initiating real-life demonstrations on mine sites, having discussions with regulatory agencies and other stakeholders ? these and many other activities were necessary before autonomy could be fully and successfully launched. After decades of effort, Caterpillar?s first official commercial autonomous mine site went to work in 2011 in Farmington, NM.

By Bernd Hagenah, Eric C. Wang

New tunnels of significant alignment lengths such as mountain tunnels, base tunnels, as well as beneath urban centers pose unique environmental challenges. This paper highlights key environmental considerations for planning, design, construction, and operations by sharing lessons-learned from the authors' extensive project experience on these types of tunnels. Discussion of unique constraints include limited right-of- way, ventilation and emergency egress during the construction phase and revenue service, safety and security, and protection of existing structures. Practical approaches and applied innovative state-of-the-art solutions addressing distinct sustainability challenges and unique requirements are shared from US and international project examples.

Jun 23, 2024

When most people think of coal mining, they envision men in soot-covered clothes and hard hats digging at deposits in deep underground caverns. These mental images commonly include coal cars rumbling on rails as they emerge from the earth, filled to the brim with rocky ore. The world of modern, longwall coal mining is a far different place. Yes, it?s underground, the miners still wear hard hats and the environment is filled with soot. However, today?s mining operations are carefully monitored and the entire process is highly automated. Five kilometers (3 miles) underground, a sophisticated, high-powered mining machine moves steadily through a 2-m (6-ft) high tunnel at an average speed of 3.2 km/h (2 mph), carving out coal, then conveying it to a crusher and carrying it to the surface. Instead of digging out the ore, a longwall mining system slices it from the exposed tunnel face, using giant rotating shears. The shorn coal tumbles onto a conveyer below the shears and is conveyed to the stageloader, where it is crushed and dumped onto the main conveyer belt that eventually hauls it out of the mine. Integral to the longwall shear and conveyor is a moving metal roof that protects it from the thousand plus feet of ground above. The ceiling panels automatically advance above the shears, powered by hydraulic roof supports that stand on the other side of the tunnel, moving in a slow, sideways lock-step with the shears. This complex and massive machine makes longwall mining the most ef?cient and productive method for excavating coal. In fact, it produces 2.7 kt to 22.6 kt (3,000 to 25,000 st) of ore per shift, versus 544 to 907 st (600 to 1,000 st) for the conventional room-and-pillar mining. Using that method, miners develop one section of a mine at a time after carving out load-bearing columns of coal to support the roof above their heads. Longwall mining also is considered safer than the room-and-pillar method, largely because the process is mostly automated, requiring fewer workers. Still, longwall mining has its drawbacks: The equipment is expensive and the mining conditions are harsh. An entire longwall system can cost between $50 million and $100 million, while the electrical controls used to operate it can cost an additional $1 million to $2 million. These investments grind away all day, every day, in hot tunnels filled with coal dust.

By A. S. Hall

Significant pyrite often does not dissolve in the Sobek (1978) nitric acid extraction; therefore, the standard conservative approach is to estimate pyrite using sulfur present in the sum of the nitric acid and residual sulfur fractions. Alunite, when present, appears as residual sulfur. Because alunite does not generate acidic effluents, overestimation of AGP can occur if all residual sulfur is assumed to be undigested pyrite. Evaluation of 16 samples from the Florida Canyon Mine revealed that petrographic examination coupled with a modification of the Sobek method to include a 6 hour hot (250°F) 'nitric acid extraction resulted in a more accurate estimation of AGP.

Jan 1, 1999

By Ulf Georg Gwildis

Overexcavation and ground loss events during pressurized-face TBMadvance in soft ground can result in unplanned deformations above the tunnel and damage to existing infrastructure. Successfully managing the risk of this occurring is crucial for any project in an urban area to proceed. Common risk management approaches include a combination of establishing suitable ranges of TBM operational parameters and using geotechnical instrumentation for deformation monitoring. Another risk management tool is material flow reconciliation, which varies depending on the specified mining method and the equipment choices by the contractor. This paper compares recent and ongoing projects in the Pacific Northwest regarding overexcavation risk management.

Jun 13, 2023

By Duncan M. Lamb

Commercial computer "time-sharing" is a new and powerful tool for the engineer. It is a system of virtually simultaneous use of a digital computer by several individuals. Access to the computer is by means of a conventional teletypewriter which transmits over the regular telephone lines to the computer which may be located any distance from the user. Complex or repetitive computations can be programmed and the speed of computation is many times that which one can do with slide rule and desk calculator. The availability of such a commercial computer "time-sharing" system offered an opportunity to transform a tedious and time-consuming task into one that requires only a few minutes. Until the work of F. C. Bond produced widely accepted mathematical statements concerning the performance of grinding mills, the selection of the proper size equipment was done by comparison with similar operating equipment. Allis-Chalmers systematized Bond's work in a bulletin published in 1963 but the calculations are laborious and the final mill selection still required comparison of the calculated power draw with the power requirements listed in equipment catalogs. This was, however, a step forward from previous procedures. This paper discusses a rapid and simple method of determining the size and power requirement of overflow ball mills. A shared-time computer program has been developed which rapidly calculates and displays the physical dimensions, power requirements, grinding media size and quantity, as well as the important correction factors used. All of these data are calculated from input information which is usually available.

Jan 1, 1969

By Jun Han

Coal has been mined in the Kailuan mining area for more than 130 years. The remaining reserves consist of, in large part, coals that would have been considered economically unminable or technically not feasible by the previous generations. Some of the current operations have to resort to overmining because the lower seams had been extracted in the past. This paper deals with the feasibility and proper layout of mining roadways of overmining carried out in the No. 5 seam of Qianjiaying coal mine of Kailuan mining area using numerical and physical simulation. FLAC2D was used to investigate the characteristics of stress and displacement in the overburden after extraction of the lower seams. It also analyzed the proper layouts of gateroads in the upper seams, i.e. locating them in the stress-relief zone of the gob so that their stability can be easily maintained. In addition, a two-dimensional physical model was constructed for investigation of damages to the upper seams due to mining of the lower seams. Finally, based on the results of investigations, proper gateroads layout was designed and successful extraction was implemented for panel 1357 in the No.5 seam.

Jan 1, 2009

By Richard H. Lindgren

I appreciate this opportunity to discuss with you OPIC's new policies designed to assist U.S. minerals companies in developing new sources of minerals overseas. A comparison of recent figures on U.S. investment in mineral exploration, development and production gives results which are remarkable --and disturbing. Through the 1960's the flow of U.S. foreign direct investment in mining and smelting in the developed and less developed countries were nearly equal. However, by 1973, roughly 80% of all exploration expenditures by mining companies was taking place in the developed countries and principally in the U.S., Canada and Australia. Clearly it is to the interests of both the developing countries and the United States to put these figures back in better balance. As you may be aware, the administration as a whole is examining systematically what can be done by government to reduce the disincentives and increase the incentives to mineral investment in the less developed countries --the LDCs. A subgroup of the National Advisory Council chaired by the Treasury Department has been formed to coordinate U. S. Government policy and program efforts relating to mineral and energy development in these countries. Among other matters, this subgroup will examine how public policies could positively influence the private investment decision-making process in the minerals industry.

Jan 1, 1978

By Robert L. Sundeen, Richard V. Wenberg

Overshot loaders are loading machines which fill a front-mounted bucket by crowding and bucket lifting, passing the loaded bucket over the machine and throw¬ing the load into a haulage unit to the rear. The load is retained in the bucket as the load mass is accelerated in its path over the machine. At the point of discharge, the bucket is stopped suddenly and the load leaves the bucket, following the throw trajectory past the rear of the loader. Fig. 1 shows a typical overshot loader of this type. Overshot loaders were developed for loading in nar¬row drift headings and drawpoints, where it is impossible to place or pass a haulage unit alongside the loader. Haulage access is to the rear of all overshot loaders. The first overshot loader was developed in the early 1930s. The early machines were rail-mounted, air¬powered, and had small loading capacities. To this day, the same basic design configuration exists, and all suc¬cessful overshot loaders still use compressed air. Bucket sizes range from 0.14 to 0.59 m3 (5 to 21 cu ft). The most commonly used machines are rail-mounted, al¬though crawler versions are popular for special applica¬tions, particularly shaft sinking. Rubber-tired machines have found some application where a greater travel distance is required between the loading and discharge points. CONDITIONS INFLUENCING APPLICATION Roadway Type Rail-mounted loaders are used where soft bottom requires rail support or where the long haul is ac¬complished with rail. This situation usually occurs in civil tunnels or in mine drifts that will continue to utilize rail-bound main haulage after development work is completed. Crawler and rubber-tire mounted loaders are used where the roadway surface is rough and lateral travel beyond the range of rail-bound machines is required. Work Area Dimensions The largest rail-bound loaders can clean roadways as wide as 4 m (13 ft) from a single track. Wider headings require multiple trackage. Headroom require¬ments are dependent upon the path described by the bucket as it passes over the machine. The largest over¬shot loader requires approximately 3.4 m (11 ft) of headroom. It follows that the largest heading that can be driven by overshot loaders from a single set of rails is approximately 4 m (13 ft) wide and a minimum of 3.5 m (11.5 ft) high above the rail. The smallest rail-bound loaders can work efficiently in headings as small as 1.8 m (6 ft) wide by 1.8 m (6 ft) high above the rail.

Jan 1, 1982

The Iron Ore Company of Canada (IOC) is the largest manufacturer of iron ore pellets in Canada and its customer base covers North American, European and Asian steel producers. The company operates a mine, concentrator and a pelletizing plant in Labrador City, Newfoundland and Labrador, as well as port facilities located in Sept-Iles, Quebec. It also operates a 418-km (260-mile) railroad that links the mine to the port. IOC has approximately 1,900 employees. Its shareholders are Mitsubishi Corp. (26.18 percent), Labrador Iron Ore Royalty Income Fund (15.1 percent) and the international mining group Rio Tinto, which is its major shareholder (58.72 percent) and operator, with activities in more than 40 countries throughout the world. The IOC was incorporated in 1949 and by 1954 it had completed the Quebec North Shore and Labrador (QNS&L) rail line. IOC began mining in Schefferville, Quebec by 1954 and closed those operations down in 1982. In 1962, IOC commissioned the present day Carol Project consisting of mining, concentration and pelletizing facilities in Labrador City, Newfoundland. In 2004, IOC shipped its one-billionth tonne of ore on the QNS&L Railway. In 2005, IOC celebrated 50 years of mining history. The company expressed an interest in reducing the amount of oversize material (>1 m x 1 m x 1 m or 3.2 ft x 3.2 ft x 3.2 ft) being produced and its subsequent downstream effects, including in-pit sorting and reduction, damage to mobile equipment and significant delays in the loading pockets and the primary crushers. To achieve this goal, an oversize reduction project was undertaken by the mine that, to date, has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduced the infiltration of the emulsion into the cracks and fissures of the rockmass, resulting in reduced amounts of oversize and more consistent fragmentation throughout the muckpiles. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analyzed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By R. Pinksen

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduces the infiltration of the emulsion into the cracks and fissures of the rockmass. Reduced amounts of oversize and more consistent fragmentation throughout the muckpiles has been a result. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a of first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A Digital Vision System (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

"With up to 2,300 m (7,545 ft) of rock on top of it, the Gotthard Base Tunnel, which is scheduled to go into regular operation in December 2016 in the Swiss Alps, is not only the world’s longest, but also the deepest railway tunnel ever built. Accordingly, the temperatures in the tunnel are very high, with the surrounding rock expected to reach 45° C (113° F) once the tunnel is fully operational. Since unrestricted rail operations are only permitted in temperatures of 40° C (104° F) or less, the heat has to be controlled with suitable equipment. Large fans developed and built especially for this application by TLT-Turbo GmbH provide fresh air for regular operations as well as during maintenance and repair work. Separate fans ensure that the emergency exits are properly ventilated in case of fire. In addition to coming up with a technical solution that could handle the special challenges of this project, the engineers and planners had to develop detailed preliminary plans as well as a sophisticated logistics and installation concept.The Gotthard Base Tunnel consists of two 57-km (35-mile) long tubes, one in each direction. Including all connecting and access tunnels, the entire underground system measures 152 km (95 miles). At Faido and Sedrun, at approximately 16 and 36 km (9 and 23 miles) respectively, two multifunction stations were built that cut each of the two tubes into three sections of roughly equal length. Here, trains can make emergency stops and change tracks, if necessary. This is also where eight large axial fans made by TLT were installed that exchange the air, i.e. they extract a certain amount of heated air and inject the same amount of cool fresh air a few hundred meters further down the train tracks. In addition to the four exhaust and four supply fans, 24 so-called jet fans were installed along with associated components like silencers, shut-off dampers, drives and lubrication systems from TLT.In addition to exchanging the air, these fans are used to enable maintenance and repair operations in the tunnel. Current plans call for blocking each tunnel tube for one night per week in order to perform preventive maintenance work, thus enhancing the tunnel’s overall functionality and availability. During these hours, many people will be in the tunnel who require fresh air. “One of the major criteria for winning this bid was the fans’ ability to quickly switch between a wide-range of modes. TLT fans are among the best in the world in this regard,” said Andreas Kuhn, TLT’s project manager for the Gotthard Base Tunnel, about the selection of his company’s fans for this project."

Dec 1, 2016

By D. Diekman

Perlite is not a trade name but a generic term for naturally occurring siliceous volcanic rock. A distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands 5 to 20 times its original volume. This expansion is due to the presence of 2% to 6% combined water in the crude perlite rock. When quickly heated above 1600°F (871°C) crude perlite pops in a manner similar to popcorn. The combined water vaporizes and creates countless tiny bubbles in the heat softened glassy particles. It is these tiny glass sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite. The bulk densities of the expanded perlite generally range from 3 pounds per cubic foot (48 Kg M3) to 10 pounds per cubic foot (160 Kg H3).

Jan 1, 1985

By C. D. Litton

When methods to prevent the occurrence of fire in underground mines fail, the next line of defense is to rapidly and reliably detect the developing fire, so that subsequent evacuation and control procedures can be safely and successfully implemented. To provide this capability requires an understanding of the operational principles of different types of fire sensors, their merits as well as their limitations, and performance characteristics of the monitoring systems that control and process sensor data; an understanding of how fires develop and the different types of fires that can occur, along with their characteristics and the hazards they present; an understanding of the impact of the mine environment and routine mining activities, not only in terms of these effects on fire sensors but also in terms of the impact of mine ventilation and mine geometry on fire growth, fire characteristics and the detection process. All of these factors are components of the technology of fire detection, and when insufficient knowledge of any of these components exists, the ability to implement adequate mine fire detection systems is diminished. Within the last decade, significant advances have been made in fire detection technology applicable to underground mines. These advances include not only the development of improved sensors and better monitoring systems, but also an expanded understanding of how to deploy sensors, set sensor alert/alarm levels, account for ventilation effects, etc. In addition, there has been an increase in our knowledge of the types of fires that occur, the types of combustibles involved, characteristic times for fire growth and development, the levels of heat, smoke and gas that are produced and the hazards that result. It is the intent of this paper to provide not an overview of current mine fire detection technology and, also, to present data obtained for some smoke sensors that have potential for use in underground mines. The paper will also discuss the data, information and resources that are currently available and seek to identify those areas most in need of further research and development.

Jan 1, 2011