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By J. E. Kulas

Red Dog is a Mississippian to Permian aged sulfide deposit located in the western Brooks Range north of Kotzebue, Alaska. It belongs in the family of black Shale hosted sedimentary exhalite deposits but lacks classic sulfide sedimentary textures. Pervasive silicification, and a significant portion of the mineralization, is replacement in nature. An extensive feeder vein system cuts the footwall and the exhalite package. A Jurassic to cretaceous age compressional event has repeated the ore section through thrust faulting and folding. The orebody contains 77,000,000 metric tons averaging 17.1% Zn, 5.0% Pb and 82 g per metric ton of Ag. Weathering has locally altered the sulfides to sulfates and formed elemental sulfur.

Jan 1, 1992

By Jan Reimann

Increasing individualization with smaller quantities, growing competition from low-wage countries, and the continuous drive towards digitalization are the challenges that industrial companies in high-wage countries must face. The example of the Flender One gearbox modular system demonstrates how consistent standardization and digitalization are the enablers for AI, and thus already enable new business models and business approaches today.

Feb 22, 2026

The last decade has seen the use of powerful computerized Mine-Wide Monitoring (MWM) systems for detecting hazardous conditions in underground coal mines. Recently, the U.S. Bureau of Mines and Jim Walter Resources, Inc. (JWR) expanded the scope of MWM system to include ground control. Single-point extensometers were installed in each of 30 intersections along a tailgate entry. These instruments monitored the rate of roof sag, a sensitive indicator of roof instability. Data were collected by the mine's own computerized MWM system. The paper describes the successful integration of ground control instruments into MWM, the data reduction procedures, and the identification of several hazardous areas.

Jan 1, 1994

By R. R. Rollins

Field data combined with theoretical derivations were used to design a surface mining operation using explosive casting. Calculated casting results varied from 44 to 65% depending on bench height. This model was then applied to field tests at an eastern, contour, coal stripping operation. Results from five experimental casting shots are summarized and compared to conventional mining methods. The overburden material removed by casting ranged from 35 to 65% with an average of 50%. Fragmentation was improved and it was demonstrated that this procedure is economically attractive with a resultant cost savings of $.59/m3 or $5.93/t of clean coal.

Jan 1, 1987

By M. R. Shahan, W. R. Reed, S. Klima, T. W. Beck, Y. Zheng

Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27 percent of respirable coal mine dust can be attributed to longwall shield movement, and developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine the ability of the foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used: compressed air and blower air. Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For compressed air foam in 3.3 m/s (650 fpm) ventilation, 98 percent of agent A was intact while 95 percent of agent B was intact on the roof at three minutes after application. At 30 minutes after application, 94 percent of agent A was intact while only 20 percent of agent B remained. For blower air in 3.3 m/s (650 fpm) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 min after application, 74 to 92 percent of foam agent A remained, while 3 to 50 percent of foam agent B remained. Compressed air foam seems to remain intact for longer durations and is easier to apply than blower air foam. However, more water drained from the foam when using compressed air foam, which demonstrates that blower air foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able to withstand a typical face ventilation velocity, establishing this technique’s potential for longwall shield dust control.

Jan 1, 2017

By M. R. Shahan, W. R. Reed, S. Klima, T. W. Beck, Y. Zheng

Testing was conducted to determine the ability of foam to maintain roof coverage in a simulated longwall mining environment. Approximately 27 percent of respirable coal mine dust can be attributed to longwall shield movement, and developing controls for this dust source has been difficult. The application of foam is a possible dust control method for this source. Laboratory testing of two foam agents was conducted to determine the ability of the foam to adhere to a simulated longwall face roof surface. Two different foam generation methods were used: compressed air and blower air. Using a new imaging technology, image processing and analysis utilizing ImageJ software produced quantifiable results of foam roof coverage. For compressed air foam in 3.3 m/s (650 fpm) ventilation, 98 percent of agent A was intact while 95 percent of agent B was intact on the roof at three minutes after application. At 30 minutes after application, 94 percent of agent A was intact while only 20 percent of agent B remained. For blower air in 3.3 m/s (650 fpm) ventilation, the results were dependent upon nozzle type. Three different nozzles were tested. At 30 min after application, 74 to 92 percent of foam agent A remained, while 3 to 50 percent of foam agent B remained. Compressed air foam seems to remain intact for longer durations and is easier to apply than blower air foam. However, more water drained from the foam when using compressed air foam, which demonstrates that blower air foam retains more water at the roof surface. Agent A seemed to be the better performer as far as roof application is concerned. This testing demonstrates that roof application of foam is feasible and is able to withstand a typical face ventilation velocity, establishing this technique’s potential for longwall shield dust control.

Jan 1, 2018

By Staff

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several stages—basic (mining), intermediate processing, manufacturing of finished goods and construction. The estimated growth rate for the real GDP of the United States for 2006 was 3.2 percent. The nominal GDP was about $13.2 trillion. The value of minerals mined in the United States in 2006 rose significantly because of increased unit price for some metals—particularly copper, zinc and other base metals. There was also a significant reduction in metals stocks. Infrastructure expansion and manufacturing in China and India have been absorbing a significant portion of world output. Domestic production increased for some industrial mineral materials, mainly cement and construction sand and gravel. Production of crushed stone declined less than 1 percent in 2006 compared

Jan 1, 2007

By Dennis Ofiara

Several recent tunnel jobs have required special adaptations of hard rock TBMs. Some of the special job conditions are ?no blast? launch requirements, small shafts or launch pits, proximity to existing underground structures, and short tunnels where the TBM must be retrieved through the primary lining. This paper describes a few of these projects, and the machine adaptations that have made TBM excavation feasible.

Jan 1, 2008

By David Smith

Construction of a new transportation link frequently requires crossing under an existing highway or railroad. Although traffic diversions may permit a cut and cover structure to be built, ‘zero impact’ tunnel solutions are becoming increasingly popular. The vertical clearance between the new tunnel structure and the existing highway or tracks may be very low; sometimes less than two meters. This leaves little room for error since any ground loss can rapidly translate into surface settlement. Problems can be avoided by maintaining the stability of the tunnel face and by minimizing ground movement around the tunnel lining. This paper examines construction methods that have been used to construct short tunnels with shallow cover, and highlights factors to be considered for future projects.

Jan 1, 2005

By Ralph C. Kirby

The U.S. produces about 34 percent of the world's aluminum yet must import 90 percent of the raw materials needed. There are abundant resources of aluminum-bearing minerals such as clay, anorthosite, alunite, shale, and dawsonite, but none of the numerous processes proposed for recovering alumina from them has yet proved economically competitive with the Bayer process using imported bauxite. To help develop an economically viable process for utilizing these resources, the Bureau of Mines is testing on a common basis several proudsing processing techniques. New improvements and approaches developed by industry and the Government are being evaluated on a mall scale to obtain enough information on which to form a judgment regarding the best processes for commercial adoption. A continuous miniplant having a feed rate of about 70 pounds per hour is being operated now to investigate the nitric acid process for recovering alumina from clay. Parts of this plant will be used subsequently for work on other processes for recovering alumina from clay, anorthosite, alunite, and dawsonite. Initial results of the operation and plans for the overall project will be discussed.

Jan 1, 1974

By G. E. Vaninetti

During its modem era, the southern Powder River Basin (PRB) in Wyoming has grown from meager origins in the early 1970s to become one of the most important coal-producing regions in the United States. In 1993, production and sales of southern Powder River Basin coal exceeded 190 Mt (209 million st), or about 20% of the US coal industry. Despite the remote location of the PRB relative to its potential markets, most coal industry observers anticipate continued strong growth to meet utility compliance plans for Phases I and II of the Clean Air Act Amendments (CAAA). This article is an overview of supply and demand issues concerning the marketing of southern PRB coal. It reviews the events leading up to the recent run on spot coal and offers a forecast of demand and prices.

Jan 1, 1994

By Gary B. Glass

Seventeen percent of US coal production now comes from the 19 surface coal mines in the Powder River Basin of northeastern Wyoming. The Powder River Coalfield, which coincides with this topographic and structural basin, is unique to the conterminous US, in that it contains an estimated 934.4 Gt (1.03 trillion st) of in-place coal resources. At least 13.2 Gt (14.6 billion st) is a compliant, strippable reserve base. In 1993, an estimated 162 Mt (179 million st), or 98% of the coal mined in this Wyoming coalfield, came from the thick - average 30.5 m (100 ft) - subbituminous, Wyodak coalbed, or from the Anderson and Canyon coals in the one mine where the Wyodak is split into two separate coalbeds. The other 2.7 Mt (3 million st) of coal mined in the Powder River Basin in 1993 came from the School, Badger, Monarch and Deitz No. 3 coalbeds. In this "world class" coalfield, there are at least 13 other persistent, 3 to 15 m (10 to 50 ft) thick, coalbeds as well as the Big George and Lake De Smet coalbeds, which are each 61 m (200 ft) or more thick in places. None of these latter 13 coals are mined at this time.

Jan 1, 1994

By Thomas A. Simpson

Traveling through the moors and valleys of Cornwall, England, one is reminded of the extensive mining activities of the past. Abandoned shafts, remains of granite block wheel houses and engine houses, battered brick stacks, old calciners, overgrown water wheel pits, count house remains, overgrown waste pits, and old portals are gaunt monuments to a once flourishing mining industry. Cornwall is bordered on the north by Devon and occupies the south-western most tip of Great Britain. The Atlantic Ocean borders the promontory; to the north, the mouth of the famous Bristol Channel faces the open sea; and to the south, the English Channel separates the land masses of Great Britain and Europe. This part of England is probably the most extensively mined ground in all of Europe. Such great mines as Dolcoath and Wheel Vor, Consols and South Carodan, Levant and Bottalack, remain legendary in the annals of metal mining in the nineteenth century. Many US mining districts hold close ties with Cornwall, Devon, and Wales through ancestors who emigrated from there to work in US mines in the eighteenth and early nineteenth centuries. Their descendants can be found in many major US mining districts, and their terms, expressions, customs, and methods have left an impact on the US mining scene that remains with us today.

Jan 9, 1981

Mining steeply dipping coal seams is a difficult task. Prior to 1996, fully mechanized longwall mining methods along the seam strike direction were tried in China and other countries. Due to its larger coal reserve in steep seams, China made more, but still limited, progress on mining such seams than other major coal-mining countries. In the last two decades, accelerated research efforts have tried to improve the mining technology in steeply dipping coal seams. Based on this work, a dynamic model of a roof-support-floor (R-S-F) system under asymmetrical constraints in mining steep seams is established here, and a theory of strata control and hazard prevention is formed. The key technologies for mining steep coal seams include global and regional strata control methods in the longwall face; methods for the longwall face machines to sustain static and dynamic loads; and flexible protection technology. These theories and technologies have been successfully applied in China to the mining of steep coal seams of varying thickness and hardness, with hard and soft roof and floor, and with a high potential for spontaneous combustion. In recent years, the technology has been introduced to Russia, India, Uzbekistan and other countries where steep coal seams are mined.

Jan 1, 2013

By T. Hawthorne, H. Barnes

Homestake Mining Company has developed an estimating model, based on other closed projects, to audit and prepare new estimating plans. The results of recent closure audits reveal that the original budgets were often insufficient to cover the present expected expenses. Some of the major areas where technical challenges and costs are increasing include heap leach pile detoxification and rinsing, tailings dam closure, water management and treatment, abatement of contaminated soils, and many others. Risk and sensitivity analysis of each category will develop a level of confidence in the estimate and allow management to focus on the pertinent issues. Periodic audits of closure plans and costs throughout the life of mine serves to focus management attention on the complete costs of production. This will result in improved overall planning and management, and reduce the number of missed opportunities for savings.

Jan 1, 2000

By John Reilly

Traditional methods of project procurement of have remained virtually unchanged in the U.S. infrastructure construction industry for more than 50 years. The traditional method, Design-Bid-Build (DBB), uses a two-step process that separates planning and design from construction. Design is generally done by the public agency and their consultants and the subsequent construction contract is procured from the private sector, almost always by a “low-bid” approach. This method has worked well for many projects, delivering quality work for the lowest bid price. This is particularly true for those projects where the work, and the public agency’s management procedures, are well understood by the contracting community and there is relatively low uncertainty in the work or conditions, particularly geotechnical conditions for underground construction. However, concerns exist with the DBB process. It is time consuming because all planning and design work must be completed prior to beginning any construction work and it is of concern for complex or large projects, plus those with significant risk, where the separation of design and construction, in conjunction with pressures resulting from the low-bid environment, often result in substantial cost and schedule increases. Frequently, these increases occur in a non-productive, inefficient, adversarial work environment leading to claims, disputes and costly litigation (Quick 2002).

Jan 1, 2007

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

By N. Wahl, D. M. Blackketter, R. Thornton

This paper evaluated using a water-filled abandoned mine (Orphan Boy) as a heat source for a 240- kW closed-loop heat pump with the goal of heating a 2,000-m2 building. The mine has a 245-m vertical shaft connected to a large stope by three horizontal cross-cut shafts. There is 1,250 x 106 L of water at a consistent temperature of 24-26° C that is available mostly in the stope. The only heat exchanger placement option is in the vertical shaft. Therefore, the focus was to model heat exchanger placement in the vertical shaft to determine the extent to which the systems will induce thermal currents between the stope and vertical shaft. Modeling of thermal currents, temperature profiles and heat contribution from the ground was done using finite difference and computational fluid dynamics. An optimal configuration was determined showing sufficient water movement and heat transfer will occur with a low water temperature in the shaft above 20° C. This project supports a U.S. Department of Energy (DOE) grant that will implement the full-scale system.

Jan 1, 2013

By H. Sevim

The utilization of high sulfur Illinois coal by utility plants has been decreasing since the enactment of 1990 Clean Coal Air Act Amendment. Illinois coal producers can make their coal saleable by offering the choice of taking the combustion by-products from the utility plants and placing them in the abandoned sections of their mines. To be competitive, however, coal producers need to select an environmentally acceptable transportation-handling-placement system through which the cost-per-ton of by-product disposed can be minimized. In this paper, a few such systems are presented. The favorable operating range of each system is determined in terms of distance and tonnage. A case study is given whereby cost analysis is conducted for an underground coal mine receiving by-products from two Illinois utility plants.

Feb 24, 1997

By Jay R. Schafler, Jacob L. Brinkman, Catherine E. Johnson

"The United States coal mining industry is currently experiencing a decline in both demand and commodity price while facing implementation of more stringent air and water pollution regulations. Company profits have decreased significantly, forcing several major companies to declare bankruptcy. The industry was required to adapt to survive. Many of these companies have adjusted by abandoning mines; the last two decades have seen a drastic decrease in the number of mines. To discover the primary causes of this downturn, three major aspects must be studied: properties of abandoned mines, commodity history and regulatory impact. Trends since 1994Each year, U.S. coal mines are required to submit data on a variety of categories to the U.S. Mine Safety and Health Administration (MSHA) and the U.S. Energy Information Administration (EIA). This data include administrative records, production values and information regarding the attributes of the mined material and the mine itself. Each year since 1996, EIA has released a report summarizing the data from two years prior. Additionally, MSHA maintains a database containing a collection of all the most current data. These resources are the primary sources for the figures included in this article. There are several items to note regarding this data:1. The EIA reports from 2016 and 2017 were not released at the time of writing this report.2. The MSHA data set is actively maintained as information is provided. This means the data for 2016 is from June 27, 2016 and data for 2017 is from Aug 24, 2017. All other points represent the end of-year values.3. Each of the figures only includes data pertaining to active mines. EIA defines active mines as both active and temporarily idled mines, and inactive mines as nonproducing and abandoned mines. MSHA separates all four into separate categories, though this paper combines the MSHA values according to the EIA definition for the purpose of comparison."

Jan 10, 2017