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With the dawning of a new century came the beginning of a new era in the coal industry. Instead of the traditional practice of only buying and selling produced coal in the United States, a coal futures market was established. The New York Mercantile Exchange began trading coal futures in July 2001. But, even in this new era, many of the old is-sues that have beset the coal industry still remain, as was evident in2001. Coal production increased to are cord level during 2001, according to preliminary data from the US Energy Information Administration(EIA). Production in 2001 rose by4% to 1.01 Gt (1.12 billion st), compared with 2000 (Table 1). This barely surpassed the previous record level of 1 Gt (1.11 billion st)set in 1998. Coal consumption remained unchanged. The additional production was used to replenish the depleted stockpiles that had resulted after two years of declining coal production and increasing coal consumption.

Jan 1, 2002

By Brendan Demich, Joseph McGuire, Emily J. Haas

Near misses recorded and reported by workers can provide awarenessto the potential causes of injury and prompt safety management initiatives. Although most companies require near-miss reporting, it is unclear what the value of these reports are, if any, and how they influence subsequent actions or controls to reduce on-the-job risks. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a case study with an aggregates company in which near-miss reports were analyzed at each of their locations over an entire quarter during the summer of 2018. Within that quarter, workers recorded 249 near misses. Of those, 167 were valid near misses that occurred at work. Researchers coded the reports using a qualitative 5 × 5 risk matrix. Of the 167 near misses, 19% were deemed low risk, 25% moderate risk, 30% high risk, and 26% critical risk. Several patterns in the near-miss incidents were documented, including classification of incidents and common corrective actions referenced (i.e., elimination/substitution, engineering control or redesign, work process/procedures, and personal protective equipment). The analysis provides insight into ways that risk communication and management programs can be improved to reengage workers and their situational awareness on the job.

By James D. Nickerson

Thee Brightwater water treatment facilities, currently scheduled to be completed in 2010 and begin operating in 2011, will serve the northern part of King County, WA. The facility includes a new treatment plant and extensive conveyance system consisting of more than 21 km (13 miles) of influent and effluent conveyance tunnels and five portals. The majority of the conveyance system tunnels are mined by tunnel boring machines (TBM) and microtunnel boring machines (MTBM). Tunnel and portal construction is divided into three main contracts. The Ballinger Way receiving portal, constructed under the central tunnel contract, is the terminus for the BT-3 leg of the central contract and the BT-4 terminus of the west contract. The shaft has a 7.3-m (24-ft) finished inside diameter (ID) to accommodate removal of the central project TBM and the west contract TBM and extends to a depth of 66 m (216 ft) below grade through a complex and challenging soil profile characterized by multiple ground water tables. Vinci Grand Projects/Parsons/Frontier-Kemper Constructors (VCFK) was the joint venture team for the Ballinger Way portal. Frontier-Kemper was responsible for the shaft sinking. VCFK evaluated either slurry wall techniques or ground freezing for earth support during excavation of the portal and liner installation. The selection process took into account the vertical depth, cost, past practice, geology, water tables and a 9-m- (30-ft-) thick zone of contaminated soil at the top of the shaft. Ground freezing, which would also act as a hydraulic barrier, was deemed the better option for this project. The contract was awarded to New Jersey-based geotechnical contractor Moretrench. Typically, frozen walls, by design, key into an underlying cutoff. At the Ballinger Way portal, however, the [ ] freeze bottomed out in a substantially thick stratum consisting of predominantly clay, but with some inclusions of permeable soil that indicated significant ground water pressures. To ensure stable conditions at the bottom of the shaft, Moretrench, which also specializes in dewatering, designed and installed a perimeter array of deep wells to temporarily depressurize the permeable soils. The movement of ground water generated by pressure

Jan 1, 2009

By Glen Church, Don W. Deere, Christoph M. Goss

The Standley Lake Dam Rehabilitation Project in Colorado included the complete replacement of the outlet works. This required two 1.8m (6 ft) diameter microtunneled wet lake taps, 380m and 186m (1246 ft and 636 ft) long, a permanent valve shaft 12.2m(40 ft) wide and 32m (105 ft) deep, and a 3.5m (11.5 ft) diameter (962 foot long) outlet tunnel driven with a roadheader. The tunnels were driven in low-strength, expansive, and slickensided claystone. The paper addresses the site investigation, shaft construction, roadheader performance, shotcrete placement, tunnel convergence, long distance microtunneling, and wet lake taps.

Jan 1, 2005

By L. Lacerda

Spray-on ground support membranes (GSM) or thin support liners hold today perhaps as much potential to impact underground (u/g) ground support operations as dry and later wet-mix shotcrete when introduced to mining in the latter part of the 20th century. This emerging technology has come a long way from the time the first single component experimental coatings were tested in the mid-1980s. Due to a number of factors, including occupational health risk and mine safety regulations, it has taken quite some time for the development of non-hazardous membrane products. However, at this junction most existing u/g mines that employ more conventional forms of ground support could benefit from evaluating GSM technology as a means of improving safety and the bottom line. The same is especially true for future mine developments. This paper describes Master Builders Inc.’s CS1251 GSM product and its implementation. It discusses the situations in which GSM may replace other forms of ground support. Furthermore, it evaluates GSM costs & safety issues and looks at present applications and the potentially bright future of this technology.

Jan 1, 2002

By Brian Y. Lattimer, Kray D. Luxbacher, Jonathan L. Hodges, Manuel J. Barros-Daza

The abstract discusses the importance of predicting fire response time (the time before conditions become untenable for firefighters) in underground coal mines. It introduces a data-driven approach using artificial neural networks (ANNs) to predict response time and fire size based on measurable parameters like CO concentration, mine geometry, air velocity, and time since fire detection. The approach was tested using simulations from fire models (FDS and FSSIM), showing promising results for real-time predictions during mine fires.

Mar 6, 2022

By Thomas D. Kelly

In 1900, the average U.S. citizen’s average life span was 47 years. He traveled about 1,900 km (1,200miles) in a lifetime and resided in a home with an ice-box for food storage and oil or gas for lighting. He communicated by mail, telegraph and crude telephones with limited availability and range. By 2000, the average citizen’s life span was 77 years. He traveled an average of 19,000 km/a (12,000 miles/year) by automobile alone. He resided in a home with many electrical appliances, including refrigerators and electric lights. And he communicated almost instantaneously with any other part of the globe by several widely available means, including portable phones and e-mail.

Jan 1, 2002

Baja Mining is currently constructing the Boleo metallurgical plant in Santa Rosalia, Mexico to recover copper, cobalt, zinc and possibly manganese products from the Boleo ore. The process involves an acid seawater leach of the whole ore followed by solid-liquid separation and washing of the leach residue. Solvent extraction is used to separate copper, cobalt and zinc from solution. Copper and cobalt are recovered as cathode metal products and zinc as a zinc sulphate monohydrate. Manganese may be directly precipitated as manganese carbonate which can be used as a feedstock for manganese metal production. Laboratory testing has continued to refine various aspects of the process including iron removal, cobalt and zinc solvent extraction, cadmium cementation, cobalt electrowinning and manganese metal electrowinning. The results of this testing are reported in this paper.

Jan 1, 2012

By Len Harris

Webster?s Dictionary describes culture as: ? The totality of socially transmitted behavior patterns, arts, beliefs, institutions and all other products of human work and thought typical of a population or community at a given time. ? A style of social and artistic expression peculiar to a class or society. ? Intellectual and artistic activity. ? The art of developing the social, moral and intellectual facilities through education. The authors have nearly 100 years of combined experience in the mining industry working with and consulting to mining companies and companies engaged in the supply of goods and services to the mining industry worldwide. In this report, they present their experiences and ideas on the importance of cultural aspects in the successful development and implementation of mining ventures. Their suggestions on how to handle culture shock will be of interest to expatriate managers, operators, social workers, and engineering and construction personnel posted to overseas operations, as well as to nationals posted to other parts of their own country.

Jan 1, 2008

By Jozef F. Zurawski

Increasingly new interceptors or new Combined Sewer Overflow (CSO) projects require connections to existing tunnels. More often than not, the existing facilities are old, in poor or questionable conditions, without proper construction records or as-built drawings. Many cannot be easily inspected unless major construction effort provides flow by-pass for safe access. This paper provides general guidelines on how to approach the problem of assessing the condition of old tunnels, how to plan and design the connection with limited physical assessment, how to develop the scope of work for the bid documents and how to provide geotechnical guidelines and designs for the bid documents.

Jan 1, 2008

By R. John Caulfield

The primary water supply system for the City of San Francisco and adjacent peninsula areas consists of aging and deteriorated pipelines crossing under the San Francisco Bay (the Bay). This system is highly vulnerable to seismic damage from the nearby San Andreas and Hayward fault zones. The Bay Tunnel Project will replace the existing system with a 8-km-long (5-mi-long) tunnel underneath the Bay. The tunnel will be constructed using earth pressure balance methods and will have a two-pass lining system of precast concrete bolted, gasketed segments for initial support, and a welded steel pipe final lining. The project challenges include tunneling through both soft ground and rock conditions without any intermediate shaft access over the entire alignment. Seismic performance criteria include maintaining service flows after a large earthquake.

By Tony Peglas, Harry Asche, Eva Wood

The North-South Bypass Tunnel is a new $AUD1.5 billion underground traffic route in Queensland, Australia, a project of the Brisbane City Council. The tunnel is approximately 5.2 km long, bypassing the Central Business District, and is adjacent to and below major buildings and services. Road tunnel alignment issues include the complex southern connections to the Pacific Motorway and the design of ramps to the east and the north. A review of road tunnel alignment criteria and accident data for Australian and overseas tunnels, similar to the proposed NSBT, are discussed. The key findings of this review lead to a rationalization of the traditional tunnel cross sectional width allocation. The road alignment design elements adopted for the NSBT are also discussed. The NSBT route crosses beneath the Brisbane River. Geotechnical investigations and hydrogeological modelling are described. The crossing has a fundamental impact on the alignment and the tunnelling methods. The tunnelling methods to be adopted and the tunnel support are described. The geotechnical investigations and hydrogeology analysis culminate in the selection of a single shielded TBM for the reference design. These outcomes are related to complex issues of hydrogeology and contaminated groundwater. These are discussed in detail.

Jan 1, 2005

By John F. Gamble

Paper 1?South African experience with asbestos-related environmental mesothelioma: Is fiber type important? Neil White, Gill Nelson, Jill Murray The purpose of this review was to illustrate the importance of the type of asbestos in environmental mesothelioma. South Africa is a logical place to assess fiber type. The three major types of asbestos (crocidolite, amosite and chrysotile) were mined (all asbestos mining stopped in 2002) in South Africa. The association between asbestos and mesothelioma was discovered in South Africa. The occupational literature indicates high mesotheliomagenic potential for crocidolite, less for amosite and less still for chrysotile. Since South Africa has been a major source of crocidolite, relatively high rates of mesothelioma in the mining population is not surprising. High rates of mesothelioma due to environmental exposure is surprising, except perhaps when the authors? point out potential sources for community exposures (e.g., mine tailings used for road surfacing, golf courses, brick and plaster making; insulation in residential ceilings; children playing on fiber-rich waste rock). The authors? reviewed four studies reporting on mesothelioma cases and their sources of exposure and fiber type. Overall 23% of the known cases were attributed to the environmental (not occupational) exposure and about 90% were due to crocidolite asbestos. The proportion of environmental mesothelioma is considerably higher than in Western Australia where crocidolite is also mined. There the overall rate of environmental mesothelioma is about 6% (and less than 1% from residence in a crocidolite mining area).

Jan 1, 2007

By D. R. Brox, J. Levell

The Montana Tunnels Mine was mined out to a depth of 900 feet at the end of 1999. The first signs of instability were recognized in 1996 along the upper slope area of the northwest sector when the pit was mined out to a depth of approximately 500 feet. To extend the life of mining operations, it has been proposed to extend and steepen the northwest highwall to a depth of 1000 feet. Slope stability analyses were carried out using the UDEC software program to assess the stability and deformation of the proposed highwall design. Back analysis of an instability in 1997 along the upper slope section and highwall deformation to date has indicated reasonable agreement with the observed mode of failure and displacement monitoring results. The results of detailed analyses of the proposed highwall design have indicated very limited additional deformation, further development of tension cracks is unlikely and large-scale instability is not expected to occur. A total of 40% of additional mining has been completed and ongoing displacement monitoring to date has confirmed very limited additional movement and no further tension crack development.

Jan 1, 2001

By Georgene Renner, William R. Yernberg, Steve Kral

ABB offers complete electrical revamps of mining shovels with ac or dc drives, drive control, frequency converters with insular gate bi-polar transistor technology, intelligent control packages and visualization. Many of the world’s shovel excavators and draglines (walking excavators) were built in the1980s. After 15 to 20 years of round-the clock operation in openpit mines, these machines start to feel their age. Electrical parts are particularly vulnerable. Their performance deteriorates and availability and productivity fall. Even with regular ser-vice and maintenance, a machine of this age will accumulate 400 hours of unscheduled downtime a year. The need for a replacement becomes pressing, but the expense is often prohibitive.

Jan 1, 2005

By Bernd Hagenah, Katie Theis, Cristina Lauzon, Petr Pospisil

Lidding over or tunneling existing transportation infrastructure is currently under review in several U.S. cities. The main reasons for this are the use of the created space for urban development, the reduction of noise and exhaust fumes for the residents, and, thus, a significant increase in the quality of life. The main aspects to be considered during the planning process are (1) total investment and operational costs, (2) impact of construction works on current traffic, (3) safety and fire protection, and (4) socio-environmental issues. The paper presents some basic planning principles, and experiences of recent urban highway coverages are shared.

Jun 23, 2024

By W. R. Reed, G. W. Luxbacher

Mine worker exposure to respirable coal dust and silica dust can result in coal workers’ pneumoconiosis and silicosis which are occupational respiratory diseases that have no cure and are ultimately fatal. In 2021 the Mine Safety and Health Administration reported just over 11,000 operating metal/nonmetal mines with the potential for silica dust exposure for just under 200,000 miners. The National Institute for Occupational Safety and Health (NIOSH) conducts respirable coal and silica dust research associated with mining through its Office of Mine Safety and Health Research. NIOSH respirable coal and silica dust research began under the U.S. Bureau of Mines (USBM), which initially examined silica dust, progressing to include coal dust, with a stronger focus after 1969 with the passage of the Federal Coal Mine Health and Safety Act. A review of extramural research to develop real-time respirable silica dust monitor is presented along with a brief history of silica dust regulation.

Feb 1, 2024

By G. ALBORNOZ, S. Utili, A. AGOSTI, C. VALDERRAMA, R. PELL

The steepness of an openpit mine’s slopes has a substantial influence on the mine’s financial return. This paper proposes a novel design methodology where overall steeper pitwalls are employed without compromising the safety of the mine. In current design practice, pitwall profiles are often planar in cross section within each rock layer: that is, the profile inclination across each layer tends to be constant. Here, instead, a new geotechnical software, OptimalSlope, is used to determine optimal pitwall profiles of depth-varying inclination. OptimalSlope seeks the solution of a mathematical optimization problem where the overall steepness of the pitwall, from crest to toe, is maximized for an assigned lithology, geotechnical properties and factor of safety (FoS).

By T. Faulkner, S. A. Richards

"The Scale-Distance formula is one of the primary means of determining the maximum amount of explosives that can be safely detonated at one time by a single delay. This paper describes a method of applying the Scale-Distance formula to the entire mining area using gridded surfaces. Using this technique, the operator can better determine the economic impact of nearby structures on the mine plan. INTRODUCTION As the surface mining of coal and stone encroaches near populated areas, precautions must be taken to minimize blast vibration damage to protected structures. The common method employed to minimize vibration damage is not to reduce the total amount of explosive in the hole (which would negatively affect fragmentation), but rather to introduce delays to reduce the amount of explosive detonated at any point in time. The Scale-Distance formula, an industry-accepted standard, may be used to calculate the maximum weight of explosive that can be detonated at one time without damaging the structure. This information may then be used to determine the number of delays required for each hole. Detonators make up a large part of the cost of blasting. At roughly $15 per detonator an additional detonator in the hole can be significant. It is normal to set off hundreds of holes at in one shot. An additional detonator in each hole can cost additional thousands of dollars per shot. The number of detonators is also a function of the depth of the holes and the hole spacing. Being able to accurately forecast the economic impact of blasting near structures improves a company’s ability to make informed decisions on how to approach property owners. Operators basically have three options when dealing with property owners: 1. Buy the property and blast without restriction 2. Negotiate with property owner for a waiver to allow unrestricted blasting 3. Comply with the legal blasting restrictions This paper proposes a method for the engineer to forecast for all points in the proposed mining area the impact of nearby structures upon the blast design. Being able to create a contour map and ultimately estimate the number of delays required for the entire forecasted mining area, the engineer can create accurate economic forecasts of the cost of blasting. The objective is to reduce the level of uncertainty in the forecast of the blast component portion of the forecast."

Jan 1, 2016

By Christopher J. Bise

INTRODUCTION Before a mine is planned in detail, a preliminary analysis is often conducted. This preplanning permits the mining engineer to make a rapid assessment as to whether or not a particular mining property warrants further consideration. In fact, a properly conducted preplanning phase can come within 10% to 20% of the actual results, thereby saving the mining engineer valuable time before committing himself to a fine-tuned analysis. The questions to be answered by mine preplanning are (1) What will be the operating conditions for the mine? and (2) How long will it take to complete the project? To answer these questions, calculations dealing with reserve estimation, production planning, man- power planning, and project scheduling are conducted. The following sections discuss these various phases of mine preplanning in greater detail. RESERVE ESTIMATION The estimation of the various characteristics of a reserve, such as quantity, grade, and thickness, is an ongoing process throughout the life of a mining venture. However, the reserve-estimation phase of mine planning is more closely associated with the preplanning phase. There are many different techniques employed in reserve estimation of solid mineral deposits; variations among them are introduced because of such considerations as ease of application or level of accuracy. In any event, each technique is developed in the following manner: (1) the mineral body is represented pictorially and then subdivided into blocks related to one or more samples of exploration data, (2) the area and volume of each block is determined, (3) the volumes are converted to representative tonnages (or, for example, grades), and (4) the results are tabulated. To illustrate this procedure, the polygonal (area-of- influence) technique will be presented due to its ease of application, flexibility in dealing with different deposits, and general acceptance. The polygonal method assumes that all characteristics of a mineral body extend halfway between a point of observation and any other point of observation. The explored portion of the mineral body is represented by polygonal prisms whose depths relate to the characteristic in question (grade, thickness, etc.) and whose plane bases relate to the area of influence of each point of observation (drill hole, etc.) as shown in Fig. 1. The polygons must be constructed in a definite order, usually clockwise and from the periphery to the center of the deposit. Table 1 can then be used to calculate the characteristics in question. Since, by definition, the polygonal method assumes that the characteristics of a mineral body extend half- way between points of observation, it becomes readily apparent that the evaluation of a vertical-drill hole exploration program requires that the sides of the polygons be formed by the intersection of perpendicular bisectors (Fig. 2). Figs. 3 and 4 show correct and incorrect construction of the polygons. The criterion for correct construction of the polygons is that all points within a particular polygon must be closer to its rallying point than those located in any other polygon. This is clearly not the case for certain points that are located in the polygon containing rallying point B in Fig. 4. Although this method can be used where the drill holes are irregularly spaced, calculations become less tedious when a square net (Fig. 5) or a chessboard (Fig. 6) grid is adopted. The numbers shown in Figs. 5 and 6 represent the relative weight for each of the shaded areas. In general, the greater the number of polygons, the more continuous the mineral body, and the more regular the grid, then the more accurate the computations will be. PRODUCTION PLANNING Before an acceptable evaluation of the production potential of a mine can be determined, a thorough exploration program should be conducted. It seems obvious that the nature and properties of the deposit and adjacent strata, the presence of impurities, and other mining conditions should be adequately determined prior to production planning and equipment selection. The lack of sufficiently detailed knowledge of the many mining parameters has led to the failure of numerous operations. For example, targeted production tonnages and equipment sizes for a coal mine are intimately related to the seam thickness. Needless to say the quality of information that is gathered from an exploration program can have a tremendous impact on the production plan. Production plans are developed initially by determining reasonable shift tonnages per operating section. Most of the time these values are developed from his-

Jan 1, 1986