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By S. P. Lewis, R. L. Sundeen

Most of us are aware of the ever increasing use of underground space. At the Advisory Conference on tunneling in Washington, D. C. in June of 1970, the demand for construction oriented tunneling during the 1970s was estimated at some 21,000 Km of length with an excavation volume of 675 million cubic meters. Of this total, 11 million cubic meters were forecast for underground parking. Though this is a small portion of the total, it is significant to note it represents a 280% increase over the previous decade. Other areas of unusual increase were railroad tunnels, 150%, and rapid transit tunnels, 160% (1). Faced with this increasing demand, the need for improved excavating efficiency is obvious. Great strides have been made. In Japan, for example, several new long tunnels have been driven parallel to old existing ones at costs as much as 50; under those of the original tunnels (1). This is an impressive achievement. I am certain, however, that we would all agree that even greater improvement is required. Great emphasis is being placed upon sophisticated systems which include among others, mechanical borers, thermal fracturing, and various methods of rock weakening and softening. However, in hard rock excavation the fact remains that the drill-blast method continues to be the most widely used system. Undoubtedly it will continue to be one of the most important techniques in the forseeable future.

Jan 1, 1974

By LeRoy D. Loy

To facilitate effective land reclamation and comply with existing state regulations, surface coal mine operators have in recent years adopted new mining techniques and equipment utilization for steep-terrain mining. In contrast to direct spoiling with draglines or shovels, these new mining methods require some form of overburden haulage from the excavation face to the point of reclamation. Although current mining methodologies such as Block-Cut, Modified Block-Cut, and Mountaintop Removal with Head-of-Hollow Fills have proven effective in achieving reclamation objectives, some production problems have resulted from pit congestion and excessive equipment delays. Recognizing this problem, the United States Bureau of Mines contracted Skelly and Loy to design innovative mining concepts utilizing conveyor haulage in place of trucks, loaders, dozers and scrapers. Project objectives required definition of current bottlenecks and development of mining systems to: alleviate bottlenecks; increase production potential; facilitate additional resource recovery; enhance reclamation; reduce safety hazards; and improve mining economics. Successful completion of project goals within a four year program involves systematic implementation of the following separate work phases: 1) Develop Concepts for Block-Cut Mining Systems; 2) Determine the Economic and Technical Feasibility of Concepts; 3) Prepare Detailed Design and Specifications of Concepts; and 4) Prepare Specifications for Conducting Field Tests of the Most Promising Concepts. At the time of this publication, Phases 1 and 2 are finalized with Phase 3 efforts well underway.

Jan 1, 1977

By Frank W. Luerssen

Introduction "Austerity" is perhaps an overly generous description of the past three years in the American steel industry. Steel plants operated at an average of only 57% of their capability in 1982-84. The dismal losses for last year are still being totaled. But during the two years before this period, American steelmakers recorded an aggregate net loss of a staggering $6.8 billion. Steelmakers responded by closing numerous marginal facilities. And production capability was cut by 13.6 Mt (15 million st). Capital expenditures still averaged $2 billion annually. But this was inadequate to maintain the existing base of steelmaking facilities. The general economy experienced a satisfactory recovery during this period. American steel, however, continued to suffer from a lagging recovery in the capital goods sector. This was due to record penetration of its domestic market by imports and from very weak realizing prices on the volume that was available. In addition to the direct influx of offshore steel products - which itself depressed prices - the industry also became painfully aware of the growing importance of "indirect" imports. These came in the form of steel-containing producer and consumer durables. Industrial equipment and autos fabricated from foreign steel accounted for the equivalent of 6 Mt (6.5 million st) of lost market opportunity for domestic steel-makers last year. That is over and above the 23.5 Mt (26 million st) of direct steel imports. Given these factors, Inland Steel was not spared from the threeyear downpour of red ink. Despite its record of continuing modernization in steel, our single-plant location in the world's best steel-consuming market, and the high proportion of consumer durables related products, such as cold rolled and coated sheet in our mix, Inland suffered aggregate losses of $277 million during the 1982-84 period. Strategic Planning The foregoing establishes a perspective - a base from which we have restructured our view of the steel industry, and of our own role within that picture. Until possibly two years ago, this present weakness in steel demand was viewed around the world as an aberration, eventually to pass. By contrast, it is now recognized that austere times are the normal steel environment. The topic here is management of resources. This implies an emphasis on strategic planning. It is worthwhile to examine some of the more critical assumptions that were driving strategies among a number of steel companies just before the 1980s. Those projected characteristics of the future steel environment were arrived at through painstaking analysis. They were carefully and heavily quantified and were generally shared by outside observers and our peers within the steel industry. • First, the assumption was made that domestic steel demand would continue to grow at an average rate of 2% per year. • Second, it was assumed that this growth in the American market would continue to be filled predominantly by US mills. It was believed that increases in steel and steel-related demand overseas would absorb much of the ominously growing capacity of third

Jan 6, 1985

By Tom Michaud, Rob Albinger, Ian Turner, Michael Rispin

Data transmission, communication, tracking, and the connection of equipment such as gas detectors, cameras, and collision avoidance systems in today's tunnel industry are critical pieces of the constructor's infrastructure. Reliability, flexibility, redundancy, and cost-effectiveness are key in selecting and implementing inte- grated systems. Both wired and wireless components are used to deliver custom solutions and can involve interconnectivity between backbones. Systems integration is important as industry adopts proven technologies from other industries. Case stud- ies are given showing how tailor-made approaches deliver needed functionality, with varying degrees of com- plexity, in various classifications of environment, in order to meet a project need.

Jun 23, 2024

By G. L. Smit

The Buffelsfontein Gold Mining Company is situated in the Klerks-dorp district of the Province of the Transvaal in the Republic of South Africa, approximately 100 miles west of Johannesburg. Gold production commenced in January 1957 and Uranium treatment of residue slimes as a by-product started in July 1957. The mining property is 5435 mining claims in extent, the equivalent of 7,988 acres or 12.5 square miles. The mine was initially exploited by the Pioneer Twin Shaft System, consisting of a 26 feet diameter down-cast shaft and a 22 feet diameter up-cast shaft, sunk in the north-west area of the mine to cater for the hoisting and ventilation requirements for a milling rate of 150,000 tons per month.

Jan 1, 1964

By D. R. Wilburn

The worldwide budget for non fuel mineral exploration was expected to increase by 27 percent in 2003 from the 2002 budget, according to the Metals Economics Group (MEG) of Halifax, Nova Scotia. The increase comes after five years of declining spending for mineral exploration. For the first time in several years, all regional exploration budget estimates for 2003 as defined by MEG would increase from similar 2002 estimates. However, MEG included 193 more companies in its 2003 survey than in 2002. As with previous MEG survey reports, estimates reflect anticipated expenditures rather than actual dollars spent. Caution, therefore, must be taken when comparing 2002 and2003 estimates or evaluating the magnitude of regional changes from year to year. Sample variations and currency exchange rates may influence year-to-year variations of MEG data. Even so, it is likely that the general climate of improved metal prices in 2003 encouraged companies that had previously left the mineral exploration sector or reduced their exploration activity to once again focus on minerals exploration or increase exploration activity and budgets.

Jan 1, 2004

This paper presents the results of a unique study conducted by the National Institute for Occupational Safety and Health (NIOSH) from 2016 to 2019 to evaluate the effects of longwall-induced subsurface deformations on shale gas well casing integrity and underground miner safety and health. At both deep and shallow cover instrumentation sites, surface subsidence measurements, subsurface in-place inclinometer measurements, and underground pillar pressure measurements were conducted as longwall panels were mined. Comparisons of the deep and shallow cover test site results with those from a similar study under medium cover reveal an interesting longwall-induced response scenario. Under shallow and medium covers, measured horizontal displacements within the abutment pillar are one order of magnitude higher than those measured under deep cover. Conversely, measured vertical compressions under deep cover are one order of magnitude higher than those under shallow and medium covers. However, FLAC3D simulations of the casings indicate that, in all three cases, the P-110 production casings remain intact under longwall-induced deformations and compressions, which has serious implications for future mine design in areas where shale gas wells have been drilled ahead of mining.

Jan 7, 2020

By John Trefny

Although mining is currently one of the smallest academic units on the Colorado School of Mines(CSM) campus, it is alive and well, with nearly 100 undergraduate and graduate students. For many years, Mines has had undergraduate and graduate programs in hard-rock mining. The school has recently transferred its physical mineral processing activities to the Mining Department. The program has also expanded to include tunneling, underground construction and industrial minerals. There are current discussions about increased research activities on cement and other construction materials. The Mining Department also teaches its share of what is called the “distributed core” courses with curricular requirements common to related programs, as well as mining safety and health, in conjunction with our continuing education department.

Jan 1, 2002

By Paul C. Schmall, Arthur B. Corwin, Derek Maishman

Ground freezing occupies a unique and important niche in underground construction, fulfilling a geotechnical need that is difficult, or sometimes impossible, to fulfill through other groundwater control and excavation support methods. Where complete groundwater cut-off and in-built ground support are required, and deep excavation is planned or the work occurs in difficult or disturbed ground, ground freezing offers the assurance critical to safe and timely construction. Compared with other groundwater cut-off or excavation support methods, a frozen wall is easily connected to underlying bedrock and will also adhere to adjoining subsurface installations or obstructions, if necessary, to provide a composite cutoff structure. Ground freezing is effective in all soil and ground conditions and has been used for emergency situations in disturbed, displaced or loose ground, where detailed soil characterization could not practically be performed.

Jan 1, 2005

By Ian Martin

A precious metals refinery’s switch to personal computer-based, three-dimensional piping design saved many hours in the design of a South African precious metals refinery. Bateman Minerals and Industrial provided engineering, procurement and construction management services for Impala Platinum Limited-Refineries’ new $60 million refinery in Springs, South Africa. This project is one of the largest platinum refineries in the world. Bateman evaluated a new design method during this project that involved developing a three-dimensional model for the project. The new method saved time by reducing the man-hours required to generate complete project documentation, including plans, sections, isometrics and material takeoffs. The new method also saved design and construction time by allowing designers to detect clashes before construction began.

Jan 1, 2000

By M. H. Dunn, T. P. Danehy, C. F. Denholm, S. L. Busler

The problems associated with abandoned minelands are so extensive that neither federal, state, or local governments nor the mining industry nor watershed groups can adequately address these problems individually. By combining talents and resources, however, these problems are being solved efficiently, effectively, and economically. Utilizing existing water monitoring data, local public-private partnerships have successfully designed and built passive systems within five weeks to six months which treat discharges up to hundreds of gallons per minute that vary in quality from net alkaline to highly acidic, containing as much as 200 mg/L dissolved iron and 70 mg/L dissolved aluminum.

Jan 1, 2002

When it comes to safety in the mining and extractive industries, success is literally a matter of life and death. Anything short of perfection is not acceptable. In recent years, the mining industry in the United States has made tremendous strides in terms of health and safety for its workers. Part of that success has come with an increased focus on the issues of safety, an intense examination of procedures, liberal sharing of best practices and a focus on the synergy between safety, reliability and environment. During his closing keynote address of the Safety Management & System Reliability Conference in Minneapolis, MN on Nov. 15, Joe Driscoll, vice president of Great Basin Gold, showed a calendar from the coal fields in Pennsylvania from the early 1900s. The calendar marked the number of mine-related deaths each month. Some months, the number was as high as 50. It was an illustration of how far things have come, but there is still much more work to be done.

Jan 1, 2013

By G. Biles, K. Loughran, R. Anand

The Eskay Creek Mine, a high-grade gold and silver underground mine in northwestern British Columbia started operations in late 1994. For the first three years of operation, ore was crushed to minus 2 inch; blended to satisfy smelter terms and direct shipped to smelters in Japan and Canada. Before commencing the above operations, preliminary evaluations had indicated that an extremely complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. Subsequently markets for raw ore were identified and underground mining and ore transportation operations, at a nominal production rate of 300 tonnes per day, were commenced. Exploration diamond drilling in 1995 and 1996 discovered additional lower grade mineralised zones, which are less economic or uneconomic as direct shipping ore. Test work demonstrated that these lower grade zones could be upgraded to marketable concentrates in a simple flotation mill. The mill was built in 1997 and has been in operation since late 1997. The mining rate now has increased to 400 tonnes per day including 250 tonnes per day of the direct shipping ore and 150tonnes per day of the mill ore. Prime Resources Group Inc. wholly owns the Eskay Creek Mine. Homestake Canada Inc. owns 50.6% of Prime’s shares and manages and operates the mine on Prime’s behalf. This paper discusses the mining and milling operations as well as ore shipment and smelter contracts' administration.

Jan 1, 1999

By A. L. Williamson, G. Savci

Hydrologic assessments of existing and proposed waste rock stockpiles (WRS) are typically required for application of operating and closure permits at mine sites. The results of these assessments can be used to determine the applicability of the state groundwater permit program requirements to the operation and closure of these stockpiles. The objective of this hydrologic assessment was to ascertain whether or not the WRS at the Ajo Mine have a reasonable probability of discharging potential pollutants to the underlying aquifer under the operational mine conditions. The hydrologic assessment was performed based on an evaluation of climatic data, prediction of the net infiltration rate through the WRS and prediction of additional hydrologic factors such as the time required to deplete available moisture storage in WRS. The predicted net infiltration rates ranging from 0.13 inches/year (1.1x10-8 cm/s) to 0.24 inches/year (1.9x10-8 cm/s) are below the threshold value of less than 10-7 cm/s recommended by Hutchison and Ellison (1992) as being characteristic of conditions that produce no or negligible quantities of seepage. In addition, the total time required to deplete available moisture storage within the Ajo Mine WRS and for any potential seepage from the WRS to reach the underlying aquifer is estimated to range from 260 years to 1,950 years. Collectively, the climatological and geotechnical investigations and the hydrologic predictions demonstrate that the WRS at the Ajo Mine hydrologically do not have a reasonable probability of discharging pollutants to the underlying aquifer. As a result of this prediction, the stockpile will not be regulated under the state groundwater permit program and operational and reclamation requirements will be limited to managing surface water runoff.

Jan 1, 2002

By Alvin Kaufman

Malthus, an eighteenth century economist, predicted a rather dismal future for the world. It was his contention food supplies would not be sufficient for the population of the world because the economy of a nation grew arithmetically while population increased geometrically. As a consequence, within a relatively few years mass famine would spread throughout the world. This prophecy, based on an agrarian economic situation, did not come true at least insofar as the Western World was concerned. In largo measure, the salvation of our part of the earth resulted from the growth engendered by the Industrial Revolution. Throughout much of today's world, however, the Malthusian theory seems to be coming true. The advantages and benefits of the Industrial Revolution have net reached all nations. Further, the situation has been compounded by the benefits of modern medicine. This has reduced child mortality and extended life expectancy, but placed no limitations on births in the developed countries, child mortality has declined to 2 percent and adult life expectancy has doubled, but education and general prosperity have resulted in voluntary limitations on pregnancies thus partly offsetting the increased chance of survivals Even so, the present rate of population increase in Europe is approximately 6 percent per decade, and somewhat higher in the U.S., Japan, and other developed countries. The world as a whole, however, is expected to double its population by the year 2000, This would imply a rate of increase in the less developed countries approximately four times that in Europe.

Jan 1, 1966

By Dejan Petrović, Pavle Stojković, Jelena Ivaz, Saša Stojadinović

In spite of the fact that flyrock phenomenon represents the real threat for personnel and machinery, it still remains insufficiently investigated. There are efforts, in the mining community, to explain the causes of flyrock, but the models capable to accurately predict flyrock occurrence and define the flyrock distance still do not exist. This article is an attempt to establish such a predictive model. The model utilized the adaptive nature of artificial neural networks and combined it with the accuracy of numerical modeling of physical phenomena. Necessary data were collected by high-speed camera recordings of actual blasts at three different surface mines and processed for further use for artificial network training. The result was a neuro-numerical couple which was capable to predict flyrock occurrence, estimate the launch velocity of flyrock fragments, and calculate the maximum distance of flyrock fragments. The safe distance was then calculated by multiplying the flyrock distance with a factor of safety. The article explains the procedure for data acquisition and processing, artificial network construction, training, and validation. It also explains the principles of flyrock distance calculation and, finally, provides a definition of factor of safety and safe distance. The results showed that the prediction was satisfactorily accurate and reliable.

Oct 22, 2021

By Gary Brendel

India produces about 70 Mt/a (77million stpy) of coal ash (fly ash and bottom ash) from burning about 200 Mt/a (220 million stpy) of coal for electric power generation. The average ash content is 35%. In contrast, the United States produces about 70 Mt/a (77 million stpy) of coal ash from burning 800 Mt/a (880million stpy) of coal for power generation. Its average ash content is less than 10%. In 1998, GAI Consultants Inc.(GAI) embarked on a federally funded, multiyear project to assist the government of India in solving its growing coal-ash management problem.

Jan 1, 1999

China has made great progress in thick coal seam mining, commonly characterized by longwall top-coal caving mining and single-pass longwall mining with a large cutting height. At present, the maximum mining thickness of longwall top-coal caving reaches 20 m while that of single-pass longwall mining approaches 8.8 m. The top-coal caving–related technologies have significantly improved the mining efficiency of thick coal seams and have also made a great contribution to the centralized underground mining of coal. Thus, the number of underground coal mines is greatly reduced in China. However, due to the increase of the mining height and the changes in mining operations, the overburden movement caused by the mining of thick coal seams is more intense, and the influence scope is larger, which brings a series of new problems on ground control of longwall faces. In order to enhance ground control and improve the mining efficiency of thick coal seams

Jul 28, 2020

By Lawrence A. Engel

The idea of using apron feeders for in directly feeding crushers is not a new one, it has been used for many years. To the best of our knowledge, the first apron feeder was used for bulk material handling in 1893. Since that time many design innovations have been introduced, with perhaps the most effective one being, the application of crawler tractor components in the feeder construction. This design was first introduced to the mining industry in 1954 by, national iron company. These feeders were used in the handling of run-of-mine iron ore on the Minnesota iron range, at the rate of 1,000 ltph. The material was fed over a grizzly to a jaw type of crusher. The crusher output was also handled by an apron feeder. Today, the apron feeder is being used in hard rock surface mine operations feeding crushers at rates of 5,500 ltph and over.

Jan 1, 1983

By H. G. Wickes

Virtually all fluorine consumed by the aluminum industry is as the electrolyte of the Hall-Heroult process for producing primary aluminum. A small amount of fluorspar is used but most fluorine is consumed as either aluminum fluoride or cryolite. Some fluorine- containing materials are used in secondary aluminum production, but the amount is negligible compared with primary production requirements. Any analysis of the future of the primary aluminum industry must take into account two powerful and closely related driving forces which are shaping that future. These factors are increasingly stringent restrictions on the emission of pollutants and the continuing cost-price squeeze. Nowhere do these factors combine more forcefully than in the area of fluorine consumption. We can safely assume that industry efforts to reduce fluorine consumption will be intensified and that these efforts will be fruitful. This paper will attempt to identify and quantify the factors and trends of fluorine consumption during the next decade. We will be concerned primarily with the demand for new fluorine. Sources of new fluorine will not be treated.

Jan 1, 1973