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By R. L. Virta

Common clay is a natural, fine-grained material composed of hydrous aluminum silicates. Shale is a laminated sedimentary rock formed by the consolidation of clay, mud and (or) silt. Government and legislative programs The U.S. Environmental Protection Agency (EPA) invited industry to nominate representatives to a review panel that will help the EPA develop rules to regulate air toxics from the production of brick and structural clay products. The EPA was required to establish a review panel because these regulations will significantly affect small businesses. The regulation of air toxics falls under the Clean Air Act.

Jan 1, 2010

By SAMUEL A. LOLON, ADITYA JUGANDA, JURGEN F. BRUNE, JR. GREGORY E. BOGIN

Historically, there have been many events of mine fires and explosions recorded in the United States and other countries that have demonstrated the existence of explosive methane-air mixtures, herein referred to as explosive gas zones (EGZs) [1]. The risk of mine explosions can increase if these EGZs migrate out from the gob into the surrounding mine entries — a phenomenon known as gob breathing. A number of 3D computational fluid dynamics (CFD) simulations using various magnitudes and periods of barometric pressure variation have indicated that the EGZ outgassing potentially occurs due to lags in pressure, which are strongly influenced by mine conditions and ventilation systems. Early-warning systems with real-time pressure monitoring and the application of gob ventilation boreholes are recommended to detect and mitigate explosion hazards from gob outgassing.

By Georges Cote, Ehsan Alavi, Eren Kusdogan

The City of Toronto's Coxwell Bypass Tunnel is currently being constructed by North Tunnel Constructors (NTC) ULC, a joint venture of Jay Dee Canada, C&M McNally Tunnel Constructors and Michels Canada. This project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five 20 meter diameter storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. 120 m of Starter tunnel and 70 m of Tail tunnel were excavated with roadheaders to help with the launch of the TBM and as part of the contract base scope work. JayDee Canada in Collaboration with Everest Equipment Co. developed an innovative approach to design and build a stand-alone Ring Machine Erector nicknamed Enterprise to erect precast segmental lining in Starter and Tail tunnels in lieu of Cast-In- Place concrete. This paper describes the design and provides feedback on the innovative procedure used to install the rings.

Jun 23, 2024

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This paper describes the successful mechanized extraction of coal pillars in 11 panels using the fish-tail method from 2010 to 2017 at Pinoura Mine in India. This method proved its potential of coal recovery with efficient strata control under weak roof due to faster rate of extraction in a single lift. Observations of strata and snook behavior during the field studies in different panels of the mine are included.

By John Hayden

The nation runs on energy. It is essential for the economic growth and national security of the United States that the nation has an adequate, sustainable, environmentally acceptable and economically viable balanced supply of energy sources, (e.g., coal, petroleum, nuclear, natural gas, solar, wind, geothermal, biomass, hydroelectric power). Therefore, the allocation of mineral raw materials to the energy-producing sector of the economy must be a top priority that requires the total demand for energy-related materials be judged in terms of domestic supply (Fig. 1).

Jan 1, 2012

By Donald E. Ralston, A. T. Yu, Richard P. Killmeyer, Peter Phillips, R. W. Vander Laan, John N. Murphy, John R. Messineo, John Peters

Overview Coal production in the first half of 1982 remained near the high levels begun in mid-1981. Production then fell sharply during the latter part of the year due to recession-weakened demand. Even so, 1982 coal production was estimated at 756 Mt (833.4 million st), a record high that exceeded 1980's previous production record of 752.7 Mt (829.7 million st). Though 1982 coal production was substantially below industry expectations, the attained production represented a modest achievement in view of the recession's severity. In 1982, the gross national product declined 1.8%, its worst performance in 36 years. The recession, along with mild weather, improved energy efficiency, and conservation efforts caused the nation's energy use to drop 4.1%. With the iron and steel, construction, and auto industries experiencing production declines, industrial energy use fell 10.8%. The extent to which the nation's economic slump affected coal markets in 1982 varied: • total domestic coal use declined 3.4%; • exports remained strong for most of the year; • electric utility coal use declined for the first time in 25 years; • coal use at coke plants declined by one-third; and • coal use in other industrial sectors stayed surprisingly near the 1981 level. Coal Use Domestic coal use totaled 641.8 Mt (707.5 million st) in 1982,22 .9 Mt (25.2 million st) below the 1981 level. Nearly all the decline occurred at coke plants where use dropped to 37.1 Mt (40.9 million st) in 1982 from 55.3 Mt (61 million st) in 1981. The decline in all other industrial and electric utility coal markets was only 5.3 Mt (5.8 million st). Residential and commercial coal use increased 635 kt (700,000 st) to 7.3 Mt (8.1 million st) from 6.7 Mt (7.4 million st). Power generation decreased 2.3% in 1982, the first year since 1945 that output failed to increase. The decline was due to a drop in industrial demand. Electricity sales to residential, commercial, and other nonindustrial users increased slightly. But coal's competitive position stayed strong. Power generation from oil and natural gas fell 28.9% and 11.7%, respectively. Power generation from coal declined only 0.9%. Among the primary energy sources, coal fueled 53.2% of US electric power generated in 1982, compared with 52.4% in 1981. In 1982, US steel production declined to 66.1 Mt (72.9 million st), the lowest level in 50 years and down from 109.6 Mt (120.8 million st) in 1981. The reduced steel demand forced 13 coke plants to shut down. Coal Exports Coal exports in 1982 totaled 96.4 Mt (106.3 million st), 5.7 Mt (6.3 million st) less than in 1981. Despite the worldwide recession and above normal coal stockpiles in many countries, exports were higher than many expected. This showed the relatively strong US position in international coal trade. The US continued to export near-record coal tonnages despite increasingly competitive influences. These included an improvement in Australia's labor difficulties, the return of Polish coal to Western European markets, and lower oil prices. In 1982, US port facilities were improved and expanded, and more efficient methods for scheduling foreign vessels were implemented. As a result, high volume coal shipments to US ports were routinely loaded and dispatched unhampered by bottlenecks that plagued East Coast ports in 1981. Appalachian coalfield production declined 1.4% from 1981 output and 3.9% from 1980 output. The interior region of the US showed an increase of 7.8% in production. This was primarily because of a

Jan 5, 1983

By Andrew B. Cecala, Emily J. Haas, Jay F. Colinet

Researchers from the U.S. National Institute for Occupational Health and Safety (NIOSH) studied the impact of an unregulated dust control technology (the Helmet-CAM) and a regulated dust control technology (the continuous personal dust monitor) within a sociotechnical system (STS) framework to mitigate respirable dust sources. The results address how to best incorporate the overarching principles of meta-design STS during the technology integration process. Specifically, quantitative and qualitative data show that a prominent focus on the social factors within an STS framework could help reduce organizational unpredictability and may improve communication within the system to help reduce technology adoption time.

By Yong Pan, SRIVATSAN JAYARAMAN SRIDHARAN, Purushotham Tukkaraja

The block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found to be beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate the gas dilution situation when the source is located in the extraction drifts.

Sep 1, 2022

By David W. Lillie, Pier A. Abetti

This paper reports on a study of the impact of fast growing new technologies on the market for copper over the next 15 to 20 years. The greatest threat is clearly the inroads of fiber optics on the traditional market for copper in communication cable. Opportunity areas identified include heat pumps, solar power and heat, desalination, electric vehicles and others. The overall impact of new technologies on copper is expected to be modestly positive if adequately encouraged by effective R&D.

Jan 1, 1986

By R. Gong, R. Bhaskar

A coal mine study was conducted to evaluate the effectiveness of a compressed-air, foam spray system installed under a continuous miner boom and directed to cover the pan and the gathering arm. The study's objectives were to evaluate the foam, underboom sprays' effect on: • the respirable dust concentration in the ambient air, and • the quartz concentration in the airborne, respirable dust. The foam generation and delivery system's engineering design is described in the paper, followed by descriptions of the mine and the dust sampling strategy. The data were analyzed to study the foam's effects on respirable dust and quartz concentrations at the continuous miner cab, the face return and the intake. The data indicate reductions in the dust's quartz content, ranging from 19.7% to 64.6%, in eight of 11 comparisons of the foam vs. no foam cuts. In addition, airborne intake dust reductions were observed in eight of 11 comparisons.

Jan 1, 1993

By Felipe Calizaya, Sekhar Bhattacharyya

Noise-induced hearing loss (NIHL) is prevalent in mechanized underground mines. Federal regulations are often not complied with effectively. Miners are also prone to ignoring administrative guidelines and/or personal protective equipment for hearing conservation. As a result, quality of life among experienced miners plummets while occupational risks increase at workplaces. This research focused on auxiliary fans used in underground mines. These fans work at high rotational speed and generate extremely high levels of noise in close proximity to miners. Silencers used are often of little effect due to poor maintenance. A new silencer is tried in the laboratory with the objective of easy maintenance and resulting reduction of noise exposure for miners.

By V. S. Znamensky, R. V. Stewart

This chrysotile asbestos ore body is located near the northern tip of the Province of Quebec, Canada. It is some 1818 km (1130 miles) north of Montreal, 480 km (300 miles) north of the tree line, and is situated within the zone of continuous permafrost. The open pit ore zone is approximately 0.4 km (1% mile) in length, some 61 m (2OO ft) in width and plunges at 25o to 30 o below surface to a vertical depth of at least 610 m (2000 ft). The ore body was originally evaluated by programs of surface mapping, diamond drilling, and bulk sampling. The fiber is semicrude, possesses excellent strength, and good fiber length distribution. GEOLOGICAL SETTING, LOCATION, AND DISCOVERY The chrysotile asbestos mineralization at the Asbestos Hill mine occurs in serpentinized ultrabasic rocks of Precambrian age. These intrusive rocks are found in older volcanic sedimentary rocks known as the Cape Smith-Wakeham Bay belt and are shown in Fig. 1. The rocks comprising this belt overlie older basement rocks composed of granite and granite gneiss. This belt has a width of 32 to 64 km (20 to 40 miles), and trends in a general east- west direction, a distance of about 370 km (230 miles) from Wakeham Bay on the east coast of the Ungava Peninsula to Cape Smith, located on the east side of Hudson Bay. Two sequences of rock have been recognized in this belt. The lower (oldest) rocks are known as the Povungnituk group, and consist principally of massive lavas and sediments. The upper (younger) rocks are known as the Chukotat group, and are composed of pillowed lavas with interbedded sedimentary rocks. Sills of ultrabasic rocks exist in both younger and older rocks, but are more often found in the Povungnituk group. Concentrations of chrysotile asbestos, as well as nickel and copper minerals are found at or near the base of ultrabasic sills, and are most common where a change in dip occurs. The mine is situated about 1818 km (1130 miles) north of Montreal, approximately 1126 km (700 miles) north of the start of continuous permafrost, and about 482 km (300 miles) north of the tree line. The depth of permafrost at the mine site has been calculated to be approximately 549 m (1800 ft). This rich deposit of asbestos was discovered in 1957 during extensive exploration for nickel in the Ungava nickel belt. During that year, traverses conducted by Murray Watts spotted interesting looking ultrabasic rocks, and followup ground examination disclosed rich surface showings of asbestos mineralization near the present open pit. In 1958, a two-man prospecting party returned to the discovery site and a mineral exploration license was granted to Fig. 1. Location map Keewa Quebec Mines Ltd., a wholly owned

Jan 1, 1986

By Jerry M. Riggsbee, John H. Weber

INTRODUCTION The Washington Metro is a 98 mile rapid transit system that will serve the District of Columbia, southern Maryland, and northern Virginia. The construction work herein described relates to Section B-1 of this system. The contract for this work was awarded by the Owner, The Washington Metropolitan Area Transit Authority, to a joint venture doing business under the name of Ball-Shea-Norair. The partners in this venture were Gordon H. Ball, Inc., Danville, California; J. F. Shea Company, Inc., Walnut Creek, California; and Norair Engineering Corporation, Washington, D. C. The bid price for the project was $33,741,524 with a contract duration of 910 calendar days. Notice to proceed was issued January 5, 1970. The present modified price for the work is $36,866,000 with completion anticipated in July 1974. (About 1,638 days elapsed time.) The work to be done consisted essentially of construction of 3,490 linear feet of cut-and-cover track with side platform, and 600 ft cut-and-cover arch shaped subway stations. Stations are located in Judiciary Square and Eighth & G Street, N. W., areas. Decking of excavation in street areas, maintenance of traffic and utilities, vent and fan shafts, underpinning of court buildings in Judiciary Square and the Smithsonian National Portrait Building, and an electrical substation were included in the contract. Stations were constructed of cast-in-place concrete.

Jan 1, 1974

By J. Hanna

The University of Alabama Mineral Resources Institute (MRI) has developed a unique process for selective fatty acid flotation of carbon-ate gangue from sedimentary apatites "francolite" in the pH range of 4-6 without collector conditioning of the pulp. The process, which does not require an apatite depressant, was modified to beneficiate a high Mgo siliceous phosphate matrix from south Florida. The modified process includes two flotation stages, one for carbonate removal, as mentioned above, and the other for phosphate recovery from the siliceous gangue. The selective flotation separation of the carbonate and phosphate, from siliceous constituents of the matrix at various pH levels and collector dosages are discussed. In the carbonate flotation stage, about 70% of the Mgo was rejected in the froth and the phosphate flotation stage produced concentrates analyzing about 31% P2O5,0.7% HgO and 4% insol. The overall P2O5 recovery in the two stages is about 85%.

Jan 1, 1989

By Milton E. Jennings

On May 11, 1977, the SAMARCO 20-inch, 396-kilometer (246-mile) Pipeline was placed in service. This system represents the latest thinking in slurry pipeline design and is one of the main contributors to the viability of the SAMARCO Project. This paper presents the background, description and latest information on the system's operation. Special attention is given to the handling limitations of the slurry and to the unique hardware requirements.

Jan 1, 1978

By J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit-optimization stages of a mining project. This paper presents an approach for optimizing final pit limits concurrently over all realizations in a stochastic model and using a risk-management framework to manage the geologic and economic uncertainty. A heuristic pit optimizer is used to find multiple uncertainty-rated pit shells. These uncertainty-rated pit shells follow the mean-variance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk-management framework to further eliminate suboptimal solutions along the efficient frontier. This results in a smaller set of final pit shells that can be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits, and two regions are targeted as potential regions for further exploration.

By C. V. Deutsch, D. A. Silva

The geologic modeling of multiple domains is required for the prediction of mineral resources and reserves. In general, explicit methods have wide acceptance among modelers due to the ability to manually add deemed important trends and geological features into the models. As an alternative, implicit geologic modeling techniques are increasingly adopted to reduce professional time requirements. These methods aim for objective, repeatable and flexible models by replacing the manual time-consuming interpretation of sections with the interpolation of signed distance values. These techniques, however, have been developed for the binary case of two domains at a time. The current paper presents an algorithm that extends the binary case to multiple domains. The method is able to transfer large-scale geological features from data to geologic models. A case study illustrates the benefits of the algorithm and practical implementation considerations.

Jan 1, 2016

By Alejandro Sanz Garrote, Juergen Laubbichler, Fernando Triana Gracian, Paz Navarro Gancedo-Rodriguez, Andreas Feiersinger

The Combined Sewage Storage Tunnel (CSST) is part of the Ottawa River Action Plan and will greatly reduce the frequency of sewage overflows into the Ottawa River during storms. The project consists of the design and construction of two TBM tunnels running EastWest (EWT) and NorthSouth (NST) along 6.2 km in total, and multiple shafts and support buildings. Contractor Dragados Tomlinson JV (DTJV) was awarded the 169 million CAD construction contract in 2016 and the CSST will be in operation in 2020. Dr. Sauer & Partners (DSP), supported by Intecsa-Inarsa, was responsible for the detailed design of the precast concrete tunnel lining as well as the geotechnical risk management program. This paper addresses TBM selection, critical tunnel sections, geotechnical risk management and rock mass grouting as a geotechnical risk mitigation measure. Successful collaboration of Owner, Owner’s Engineer, Contractor and Contractor’s Engineer led to a safe and cost-effective design and construction

Jun 13, 2021

By William Gleason

"In a time that seems to be dominated with nothing but bad news coming from the mining industry, there is a success story that has been quietly happening in Southwestern Wyoming for more than 60 years, and it is one that is likely to continue for many decades to come.Beneath the wind swept high desert plains of Sweetwater County, WY, about 32 km (20 miles) west of Green River, lies the Green River Basin where five companies, including Tata Chemicals North America (TCNA), are mining the world’s largest known deposit of trona and, in turn, are collectively producing 15.3 Mt/a (17 million stpy) of soda ash.“We have a long-term growth story that has been, and will continue to be a steady earner for many years to come,” said J. Martin Keighley, managing director of TCNA who has been in charge of the mine, formerly known as General Chemical Industrial Products Inc., for Tata Chemicals for about three years.According to the U.S. Bureau of Land Management (BLM), Keighley is safe with his prediction of future success. The BLM estimates that there are enough reserves in the Green River Basin to last another 2,000 years. Currently, four trona beds in the Green River Basin are being mined and in all, there are 25 major trona beds that occur within the Wilkins Peak Member of the Upper Eocene Age Green River Formation. The trona deposit as a whole covers about 2,500 km2 (1,000 sq miles) within the Green River Basin.And imagine, this economic mainstay in the region was discovered accidently.Prior to 1948, soda ash, the salable commodity that comes from trona and is used in a host of products including glass and detergent, was produced synthetically. In 1938, an oil and gas exploration team working in the Green River Basin came away with a find that would change the soda ash industry and the physical and employment landscape of southwestern Wyoming forever. Within 10 years, the communities of Green River and Rock Springs, which were built largely on the back of coal mining and railroads, had another commodity beneath their feet."

Jul 1, 2016

By Yi-Hsuan Chen, Jürgen Brune, Candace S. J. Tsai, Alejandro Munoz, Connor Krause

This study highlights the significant presence of submicrometer- sized airborne particles in underground coal mines, especially around the belt conveyor drift areas. Using realtime instruments and gravimetric samplers, the assessment revealed that particle concentrations were notably higher in the belt entry compared to other locations, with a strong presence of submicrometer- and nanoparticle-sized dust. The study’s findings emphasize the importance of addressing small particle exposure, as these particles, composed of harmful substances like calcium, copper and iron, can pose serious health risks to miners. This research emphasizes the importance of improving air exposure estimation through more effective monitoring and characterization techniques to better understand and reduce workers’ exposure to hazardous airborne particles in the mining environments.

Apr 1, 2025