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By Janusz Cygankiewicz, Marian Branny, Józef Wactawik

The paper presents mathematical model of concealed fire. We consider a porous medium (goaf, coal fissures) through which air flows. The set of equations is constituted by transient, two dimensional mass, momentum and energy balance equations with sources describing oxygen loss and heat generation caused by coal oxidation. Paper presents several examples illustrating the phenomenon of spontaneous heating in goaf areas behind longwall faces.

Jan 1, 1997

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974

By Joe M. Bryan, George E. Rodger

The development of small precious metal mines in the western states has been directed at heap leach operations. Crushing plants are an essential adjunct to heap leach operations. They must meet environmental air quality regulations which generally follow a similar pattern from state to state. Prior to mine construction a permit must be obtained and an operating permit granted during or shortly after the start-up period. The typical construction permit application consists primarily of drawings, specifications and an explanation sufficient to indicate that the mass of particulate matter entering the atmosphere is below minimum standards. The operating permit may be granted following demonstrations that air emission control equipment or methods comply with information submitted in the construction permit application.

Jan 1, 1987

By Steve Kral

It is agreed in mining and regulatory circles that a safe and healthy working environment for underground miners is the major challenge for mine operators. Underground mine ventilation is complex. And it is becoming even more difficult as mines become larger, deeper and more complicated. At the Seventh US Mine Ventilaton Symposium, a group of mine ventilation experts from industry, government and academia attempted to solve some of the problems in ventilating underground mines. The meeting, sponsored by the Underground Ventilation Committee of SME and the University of Kentucky, was held in Lexington, KY June 5-7, 1995. Andrzej M. Wala, symposium chairman, commented that previous mine ventilation symposiums have focused mainly on work in North America. The 1995 symposium, however, broadened its borders to include several international papers. Of the 77 papers presented and bound into the Proceedings volume, 25 are from operations and research centers outside of the United States and Canada.

Jan 1, 1995

By Mark E. Smith

Large scale copper heap leaching in Chile began in November 1980 when the Lo Aguirre heap leach project was put into operation. At almost the same time, El Indio gold mine began production. While El Indio was not a heap leach project, it was Chile's first major bulk tonnage, open-pit gold deposit. This paved the way for the introduction of North American gold heap leach technology in the early 1980s. Heap leaching has become more popular in Chile during the past five years because it allows the exploitation of large but relatively low grade ore bodies at a reasonable cost. Pioneering research in hydrometallurgy carried out at some Chilean universities and at the Centro de Investigaciones Minero Metalurgicas (CIMM) played an important role. There are more than 10 large copper heap leach and solvent extraction/ electrowinning (SX/EW) process plants in different stages of development in Chile. Total production from these facilities will eventually increase Chile's present copper exports about 50%.

Jan 1, 1995

By George Wilson

As the economic and environmental attractiveness of conveying coal and ore slurries by pipeline increases, greater attention has been given to designing and selecting components for these pipeline systems. Pumps are one critical element in pipelining. Pumping slurries is a particularly arduous task, calling for special design and construction. The first article in this two-part series describes some factors to consider when selecting pumps to resist abrasive wear.

Jan 9, 1981

By E. Cetin

The authors describe the general problem of cut-off grade optimisation for multi-mineral deposits and outline the use of genetic algorithms for optimal cut-off grade schedules for deposits with up to three constituent minerals. Case studies are given and a comparison is made with Lane's multi- mineral cut-off grade algorithm.

Jan 1, 2002

By Ahmed I. A. Salama

This paper describes the development of computer density control for heavy media cyclone circuit at the Coal Research Laboratories of CANMET. The control objective is to reach and maintain the medium density set point in minimum time. A description of the mechanical components and instrumentation are presented. The control strategy and computer software are discussed. Testing and evaluation of the installed system are presented.

Jan 1, 1989

By Lewis L. Oriard

The authors outline the development and application of blasting methods put into use 11 years ago at the Berkeley Open-Pit Mine, Butte, Montana. The blast design uses a very short delay (5 milliseconds) between detonation of explosives charges, a feature challenged several times in principle despite its success for Anaconda. Concern is expressed over the categorical rejection of very short delay blasting which can make the difference between success and failure of major mining operations. There is ample evidence to show that the method can be used successfully and not violate the concerns of the public.

Jan 1, 1980

By Robin J. Batterham, Dave J. Robinson

The most significant trend in flotation has been the ever-increasing scale of operations. There is, however, doubt that this ongoing trend is enough to maintain the economics against trends such as falling grades, increasing mining costs, pressure on water supply and demand, rising energy demands needed for mineral processing, and a focus on whole of life value and mine legacy issues. We comment on the ramifications of broader uptake of more sustainable mining for mineral processing methods and address the specific question of whether recent progress in in-place recovery will lead to a timely breakthrough. The answer proposed is that this is possible in the next 10 to 20 years, but in the meantime the focus is just as likely to be on removal of waste (beneficiation) much earlier in circuits. Either way, mineral processing and flotation as we know it will change significantly. 

By Anthony G. Grice

This paper discusses the contribution that backfill is making to the Australian mining industry and provides some information on the largest operations together with some novel applications. Each of the three major backfill types; hydraulic, rock and paste are discussed in turn with a focus on new ideas and advances in understanding, technology and operating practices.

Jan 1, 2001

By L. Yuan, J. Soles, D. Bahrami, W. Tang, R. Thomas

Mine equipment fires remain as one of the most concerning safety issues in the mining industry, and most equipment fires were caused by hot surface ignitions. Detailed experimental investigations were conducted at the NIOSH Pittsburgh Mining Research Division on hot surface ignition of liquid fuels under ventilation in a mining environment. Three types of metal surface materials (stainless steel, cast iron, carbon steel), three types of liquids (diesel fuel, hydraulic fluid, engine oil), four air ventilation speeds (0, 0.5, 1.5, 3 m/s) were used to study the hot surface ignition probability under these conditions. Visual observation and thermocouples attached on the metal surface were used to indicate the hot surface ignition from the measured temperatures. Results show that the type of metal has a noticeable effect on the hot surface ignition, while ventilation speed has a mixed influence on ignition. Different types of liquid fuels also show different ranges of ignition temperature. Results from this work can be used to help understand equipment mine fires and develop mitigation strategies.

Mar 2, 2022

By Michael P. Foose

In 1994, more than 41 of the approximately 160 coal-fired, electrical- power plants within the six-state Ohio River Valley region used flue-gas desulfurization (FGD) units to desulfurize their emissions, an approximately 100% increase over the number of plants using FGD units in 1989. This increase represents a trend that may continue with greater efforts to meet Federal Clean Air Act standards. Abundant limestone resources exist in the Ohio River Valley and are accessed by approximately 975 quarries. However, only 35 of these are believed to have supplied limestone for FGD electrical generating facilities. The locations of these limestone suppliers do not show a simple spatial correlation with FGD facilities, and the closest quarries are not being used in most cases. Thus, reduction in transportation costs may be possible in some cases. Most waste generated by FGD electrical-generating plants is not recycled. However, many FGD sites are relatively close to gypsum wallboard producers that may be able to process some of their waste.

Jan 1, 1999

By Martin P. Schroeder

"Challenges have emerged as subway systems age and as new tunnels are bored in congested corridors or in high-risk environments. To help public transportation agencies address tunneling challenges, the American Public Transportation Association has convened numerous independent industry peer reviews composed of top experts in their fields to come together and provide recommendations and solutions. This paper provides case histories of peer reviews that include topics such as boring through toxic soils, boring underneath existing tunnels, retrofit of tunnel ventilation systems, and mitigation of water intrusion. Peer reviews are applicable to all tunnel projects worldwide. The paper will highlight the conditions of these challenges, peer review recommendations, steps taken to reach agreement, and the successes that resulted, which led to major changes, new legislation and reduction of risk. INTRODUCTION Public transit agencies face many challenges in maintaining and expanding safe transit operations, especially as systems age, ridership expands, and budgets remain flat. The development of new industry standards and federal safety regulations places further demands on transit systems, with compliance often taxing in-house resources. Studies of the state-of-good-repair across US public transit systems indicate a current backlog of $84 billion in maintenance projects, which will require an investment of $18.2 billion per year to eliminate the backlog by 2030[1]. Systems not in a state-of-good-repair may not operate efficiently, may not be available to meet the growing ridership demands, and may not meet required safety goals or reduction of risk. Innovation is another clear need transit agencies have for improving system performance and lowering operating costs.To meet these challenges, transit agencies often turn to industry peer reviews for guidance and recommendations as part of their overall strategy to maintain and grow the safe operation of their systems. As a service to its members, the American Public Transportation System (APTA) has developed an industry peer review program designed to give agencies opportunities to learn from each other and help them address challenges in operations, engineering design, and construction of their systems. Over the past 20 years, APTA has performed hundreds of peer reviews covering all aspects of transit system operations from fare collection to agency organization, project delivery methods to safety culture, and engineering design including tunneling and tunnel fire ventilation. As rail transit systems expand to meet increased ridership, it is often necessary to bore new tunnels for alignments in congested areas where surface rights-of-way are lacking. Such proposed alignments can pose significant challenges for transit agencies, as they contend with various tunneling problems."

Jan 1, 2016

By E. G. Hoover

In the mid-I 970s the rallying cry sent out by the aggregate trade associations to aggregate operators was to come to Washington and help design national legislation mandating reclamation of pits and quarries. This collective effort paid off in that aggregate operators were able to assist in the design of "livable" legislation; however, the coal mining industry took some very hard hits. A principal argument used by the aggregate industry was that relatively small parcels of land are impacted, the operations are located in or near urban areas to serve in the development of that immediate area, and are of many years duration; whereas, coal strip mines disturb many acres, are of short duration, and whose products may have world or nationwide utilization. Historically, developments in reclamation are tied closely to the regulatory systems that have been created to control environmental effects of mining. Since reclamation generally results in a cost incurred after the stone, sand and gravel has been mined and does not add to the inherent value of the mineral, there was little incentive in the past for mine operators to reclaim the land. In 1977, the Surface Mining Control and Reclamation Act (SMCRA) became the law for coal mine operators. The law states that, among other provisions, reclamation must "restore the land affected to a condition capable of supporting the uses which it was capable of supporting prior to any mining, or higher or better uses". It is of interest to note that years before the initiation of legislation leading to SMCRA twenty-eight states already had reclamation regulations that covered virtually all minerals. The scope of performance standards found in the state reclamation regulations included slope stabilization, grading, revegetation, neutralization of toxic materials, visual screening, waste disposal, control of drainage, and other sources of pollution and erosion. Environmental legislation and the consequent regulations came about because the public perceived that private industry did not properly value environmental quality and as a result the government became the policeman.

Jan 1, 1998

By Ben H. Daud

A computer model has been developed at Consolidation Coal Co.'s Central Engineering Dept. for preliminary economic evaluation of deep coal mine reserves. Since it was first formulated more than two years ago, the model has been used for the following purposes: (1) ranking studies of coal exploration projects, (2) marketing surveys, (3) preliminary sale and acquisition analysis of coal reserves, and (4) parametric analysis in conjunction with detailed feasibility studies.

Jan 1, 1979

By J. W. Rold

In 1973 housing and construction conflicts threatened Front Range gravel resources. The legislature addressed the problem by passing HB 1529, which required the Colorado Geological Survey to map the deposits and forbid local governments to change lands over commercial mineral deposits from zones allowing mineral development to zoning which conflicted with development. It charged counties to develop Master Plans for Extraction. Plans must consider resource quality, multiple-sequential-use potential, surrounding area compatibility, neighbors, quality of Life, extraction maximization and reclamation potential. Imprecisely worded statutes, budgetary constraints, lack of enforcement and political pressures have limited benefits from the law.

Jan 1, 1987

By Mark W. Cadwallader

Heap leach mining requires liners in order to contain leaching solutions for both economic and environmental incentives. The use of HDPE geomembrane liners for heap leaching is discussed in this paper. Comparison is made to clay liners, with inclusion of economic considerations. Several heap leach projects incorporating geomembranes are discussed.

Jan 1, 1987

By C. J. Kirkland

The paper describes the arrangements for the casting, curing and handling at the casting yard, of the concrete segments for the lining of the UK half of the tunnel, and the plant used for the handling of these linings at the construction site. An outline of the tunnel boring machines being used is given, with particular reference to lining handling and erection, and the extensive muck disposal systems installed. A general progress update will be given to the conference.

Jan 1, 1989

By Thomas D. Kaufmann

The 1982 recession set the US mining and metals industries reeling. Will the oncoming recession of 1991 hit as hard? Probably not, thanks to a shallower downturn, a weaker dollar and remarkable lower costs. Effects of the last recession That the 1982 recession was traumatic to the American mining and metals industry is an understatement. Quantities of metals consumed dropped. Metals prices fell despite continuing general inflation. The resulting real gross revenues of producers of each of the major metals plunged, in the trough of 1982, to levels one-fourth to two-thirds of those of the peak of 1979 (Table 1). By contrast, most industries in the United States were not hit anywhere nearly as hard. Real GNP, the aggregate of all production, slipped only 1 % from 1979 to 1982. Metals are most sensitive to the business cycle because of their applications. All metals but gold are raw materials to downstream industries. Raw materials are victims of strong fluctuations. This is because buying industries try to hold high inventories in boom periods when goods are in short supply. They reduce inventory levels in buyers markets when suppliers have idle capacity and raw materials are in ample supply.

Jan 1, 1990