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By Richard Kolada

If the emission of methane into any particular area of an underground coal mine remains constant, then the calculation of ventilation requirements is relatively simple. This is also true if the ventilation system is recirculatory. However, the emission of methane into a working area can vary considerably. There is always a risk that the ventilation will not be able to dilute the emission of methane to acceptable levels, because there are often short-lived peaks of emission which are very large. The ventilation design must therefore consider what is an acceptable level of risks and calculate the airflow requirements to meet this level. The acceptable level of risk can be calculated by examining the historical variation in methane emission into the area to be ventilated. For example, consider that an acceptable level occurs when methane emission peaks only exceed the capability of the ventilation one day in twenty. Then, from the history of methane emission, it is possible to calculate the necessary ventilation requirements. This method has been used since the early 1980s for conventionally ventilated districts. This paper examines the application of this technique to districts ventilated by recirculatory ventilation.

Jan 1, 1987

By J. R. England, W. J. Taylor

The Sudbury Basin is the scene of the mining operations of the Ontario Division of the International Nickel Company of Canada, Limited. Around the rim of the geological formation and within thirty miles of the City of Sudbury are located twelve operating mines and one open pit operated by the Company. The City, with a metropolitan population of some 100,000 lies 240 miles Northwest of Toronto. In addition, there is one mine in Northwestern Ontario, at Shebandowan, 700 miles Northwest of Sudbury. In 1973 these mines produced 16.5 million short tons of ore of which 14.9 million tons were from underground and the balance from open pit operations. Mining methods include blasthole, sublevel caving, induced caving, shrinkage, cut-and-fill and undercut-and-fill. Raise boring commenced at Inco in 1964 and is now applied at all mines in the Sudbury District (Figure 1). [ ]

Jan 1, 1974

By J. C. Yingling, V. Badaker, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

The University of Kentucky has developed reclamation cells at a surface mine in southeastern Kentucky to evaluate the impact of spoil handling (reclamation methods) and compaction alleviation methods on the physical properties of replaced growing media and on tree survival rate. From 1997 through 2001, penetration depth, penetration resistance, bulk density, and tree survival data have been collected at the reclamation cells and correlated to determine the relationships that exist between the soil physical properties at the site and tree survival. Regression models have been developed for each reclamation method evaluated using the collected data to predict tree survival rates on reclaimed surface mined lands as a function of the soil physical properties of the replaced growing media. Procedures have been developed for handling soil/spoil during reclamation that can minimize compaction in the replaced growing media. Procedures have also been developed for alleviating compaction in growing media on reclaimed and orphaned surface mined sites. These procedures, if implemented, will increase the potential for reforestation success. Finally, procedures have been developed for collecting soil physical property data for use in evaluating the suitability of spoil conditions for reforestation.

Jan 1, 2003

By R. R. Beebe

When an economic mineral deposit is first discovered, it is almost immediately defined in terms of tonnage and grade. As exploration and assessment continue, the initial definition is ordinarily qualified by such terms as "proven," "probable" and so on. Even at this stage, the fundamental philosophies of the discoverers may manifest themselves in conservative or optimistic views of the deposit's potential. It is unusual, however, for the philosophies to be expressed in terms of metallurgical performance criteria at such an early stage unless the ore is very unusual in its chemistry or mineralogy. Even before drilling is completed, the first mining plans appear, with or without the benefit of metallurgical test data. This is the point at which management philosophies can have some of their greatest impacts. In ideal cases, where large, uniform ore bodies can be developed and mined according to assay cutoffs, the conventional philosophy of maximizing tonnage while minimizing cost can be followed without much metallurgical difficulty. Unfortunately, such cases are rather uncommon. Even large, low-grade

Jan 1, 1991

By T. Hudaverdi

Airblast, the focus of the paper, is defined as blast induced atmospheric pressure waves. High overpressure levels may cause breaks of windowpanes, and plaster cracks. Additionally many mines come across psychological responses of residential areas. In this paper the monitoring of air blast is explained and evaluation procedures are defined. The allowable limits of the air blast are presented. The scaled distance approach developed for the prediction of airblast is explained. For the very rapidly growing cities, like Istanbul, the required raw materials for the construction industry are supplied from quarries in the vicinity or from inside of the city. With further growth of the population density, many quarries approach suburban areas and it will be more important to minimize the adverse effect of the blasting operations in the near future. In this paper the airblast levels that monitored in Cendere Region Quarries near Istanbul are presented. The suggestions put forward to control airblast levels.

Jan 1, 2006

By T. Gouri Charan, G. V. Rao

A spherical agglomeration process for the separation of scheelite fines of less than 30 µm in very low concentration of 0.04% WO3 in a binary mixture with quartz fines of less than 30 pm has been described. A concentrate containing 14% WO, with more than 90% recoveries could be achieved by means of anionic sodium sulfo succinate collector at pH 3.5 and also with commonly used anionic sodium oleate at pH 10.5 as per the conceptual flowsheet suggested. Such a process is envisaged as commercial potential for the recovery of fine-grained scheelite present in the tailings of gold plants as found in India.

Jan 1, 1991

By Brad C. Lewis

The coal mining industry has experienced a general trend toward longwall operations. An increasing percentage of underground coal is being mined by longwalls. And productivity in longwalls is likewise increasing. Operators of longwalls, however, have not yet reached a state of mining euphoria. Competitiveness within the industry and from alternate fuel sources is forcing continued pursuit of higher productivities and lower costs. [Figures 1, 2 and 3] present trends in the industry. Longwall mines, as defined here, are those reportedly having longwall installations in each of the respective years. Production from both the continuous miner and longwall units is included in the longwall mines. Nonlongwall mines are all other underground mines. Productivity calculations are based on total employee-hours associated with the operation. Annual percent increases in productivity appear to have peaked in the 1985-1987 time frame. This was due, in part, to implementation of technological advancements and improvements in management-labor relations. The results shown in [Fig. 3] aroused the author's curiosity. The first question was "Have technological advancements to increase productivity peaked?" It does not appear so.

Jan 1, 1990

By Michael E. Allen

The building of sanitary and storm drainage sewers in urban or environmentally sensitive areas often requires the use of tunnel construction procedures. While hydraulic considerations may require only small diameters, traditional tunneling techniques make small sizes the least economical. Current state-of-the-art techniques using highly mechanized systems of pipe jacking can provide cost effective solutions to the problems of construction of small size tunnels. The characteristics of mechanized pipe jacking allow rapid advances under difficult ground conditions. The basic pipe jacking cycle is used with a variety of excavation systems to permit the contractor to satisfy engineering as well as economic parameters. These characteristics and several of the systems available are outlined.

Jan 1, 1981

By Timothy N. Dunne, Joseph M. Gonzalez

This paper presents the case history of a comprehensive geotechnical investigation for the Crosstown Transport Facility, a 10,880 m long, 3.2 m diameter pressure tunnel proposed for construction in San Francisco, California. The proposed tunnel would be part of the City and County of San Francisco's Clean Water Program, and its purpose would be to convey stormwater and sewage from the east side of the City to the Pacific Ocean. Tunneling conditions were defined by surface geologic mapping, 94 exploratory borings, surface and borehole geophysics, aquifer testing, Goodman Jack testing, pressuremeter testing, and laboratory testing. Through the use of advanced coring techniques and a strictly controlled drilling fluid system, core recovery averaged 90 percent in the sheared and fractured rock of the Franciscan Formation. As a result, over 1,400 linear meters of rock core was recovered and is available for examination.

Jan 1, 1983

By Z. T. Bieniawski

In the past 15 years, rock mass classifications have experienced unprecedented development and have emerged as powerful practical methods for assessing ground conditions and tunnel support. Such methods as the RMR System (Geomechanics Classification) and the Q-System have provided many advantages over the classical Terzaghi rock-load method introduced in 1946. These new classifications have found wide applications all over the world but some doubts have been expressed and shortcomings pointed out. The author, who developed the RMR System, takes a penetrating look into the promises and the pitfalls of modern rock mass classifications. He dispels some misconceptions and shows how rock mass classifications can serve as effective and dependable design aids in tunneling.

Jan 1, 1987

By S. Barkhoudarian, R. R. Gupta, R. F. Steinberg

A study of the feasibility of using acoustic signals to detect discontinuities ahead of excavation has shown that reflecting interfaces in a homogeneous rock can be easily identified. Moreover, discontinuity interfaces in a very complex field site (where the rock face was weathered, was full of jointed rocks, and had a destressed zone running along the mine walls) could be identified with a reasonable level of confidence, using a cross-correlation technique for signal processing. The results of this study go a long way toward proving the feasibility of the technique. However, further development work is needed to optimize an operating system in a hard rock environment where boring machines are used for excavation.

Jan 1, 1997

By Tench C. Page

The Yarnell gold deposit is located 1.5 km (1 mile) south of Yarnell in the Weaver mining district of Yavapai County, AZ (Fig. 1). Elevations within the area of the deposit range from 1400 to 1560 m (4590 to 5120 ft). Historic production, principally from quartz veins localized along the Yarnell fault, was about 200 kt (220,000 st) at an average grade of 6.9 to 10.3 g/t (0.2 to 0.3 oz/st) gold. The federal government closed the mine in 1942 due to World War II. Norgold Resources Inc. leased the property in 1988 and joint ventured it with Asarco the same year. Asarco drilled 7822 m (25,660 ft) in 96 reverse circulation and four diamond drill holes and identified 8 t (260,000 oz) gold reserve. IBema Gold Inc. acquired Norgold in 1991 and is currently permitting the project. Production is expected to begin within the next two years

Jan 1, 1994

By William A. Holgate

Coal production in the in the Powder River Basin began its tremendous expansion during the boom of the mid-1970s. New mines were opened from 1976 through the early 1980s. This expansion soon placed Wyoming at the top of the list of coal producing states, where it has since remained. Mines are operated by large companies, with safety and production having equal priority. These mines have been some of the safest ever in the coal industry. Many Sentinels of Safety Awards have gone to them. Safety programs are varied, but there are commonalities. Mine safety at Wyodak Extra training is required of all supervisors. The company offers to pay for any additional first-aid training that employees participate in. Safety departments conduct weekly safety talks. All employees receive the monthly magazine Family Safety and Health compliments of Wyodak. Electricians receive extra training on electric wheel motors, from General Electric. Equipment operators receive extra training from Dresser.

Jan 1, 1994

One of the most challenging and ambitious dump rehabilitation projects in South Africa’s mining industry is being carried out at Greenside Colliery’s smoldering coal dump, which lies adjacent to the N 12 Johannesburg-Witbank highway. Greenside Colliery is the largest coal mine in the Gold Fields Group. It began operation in 1946, the year in which the burning dump had its origins. Today, Gold Fields plans to spend R16 million (about $USS8 million) to encapsulate the dump, bringing it into compliance with South Africa’s Mining Environmental Management Programme, according to Martin Hamer, engineering manager of the Greenside Colliery. The improved environmental management approach will result in reduced sulfur dioxide gas, smoke and dust emisson into the air and an enhanced aesthetic appearance of the dump from the N 12 highway. The objectives of the project are to place and compact coal discard to within the National Institute of Coal Research specifications in order to prevent spontaneous combustion, and to preserve as an asset the coal portion of the discard.

Jan 1, 1994

By Anthony G. Fonseca

About 45% to 50% of the coal mined in the United States passes through coal preparation plants. East of the Mississippi River, this number increases to about 75% to 80%. Although the cost for coal preparation is worthwhile to some, the coal industry faces the challenges of continuing downward pressure on the price of coal and the impact of new environmental regulations. Coal preparation is an effective process that achieves 75% to 80% ash reduction, 15% to 80% trace element reduction and 85% to 90% Btu recovery. It is less effective for pyrite reduction (35% to 70%) and on-line operating time (40% to 60%). It also suffers from obsolete control systems. In coal preparation, raw coal is modified to a more preferred form to enable its use. The methods used to achieve this modification must be cost-effective and appropriate to the raw coal, the scale of production and the end-user requirements.

Jan 1, 1995

By N. S. Margaris

The vegetation of Mediterranean ecosystems is distinguished by its resistance to adverse environmental conditions, and that is the reason for examining the possibility of growing species of this flora in waste disposal sites (WDSs). The survival and growth of vegetation established at a waste disposal site is dependent to a large extent on the qualitative and quantitative characteristics of the material used in the final soil cover. In the Ano Liossia WDS, where extensive remediation work is under way, three areas were examined, which met certain criteria in relation to the age of the underlying waste and the existence of impermeable material in the final soil cover. Laboratory analyses have determined soil parameters and nutrient and heavy metal content. Alongside this, at all three sites a network has been installed to monitor the qualitative characteristics of the gaseous phase of the soil cover material. The results showed the existence of a soil material containing few nutrients and the prevalence of oxygen-poor conditions, accompanied by large concentrations of CH4, CO2 and H2S, at depths of up to about one meter.

Jan 1, 2002

By R. Mohr

Storm water runoff from mine facilities such as haul roads, waste disposal sites and ore bodies have become recognized as the primary facilities associated with non-point source drainage. Depending on the ore body, facility design and geographical setting, nonpoint source drainage can cause pollution impacts to local surface and ground water resources. Non-point source impacts from surface mine drainage have become an important regulatory issue for the mining industry. Implementing non-point source drainage control plans that prevent impacts to water resources can be accomplished cost-effectively with moderate labor requirements. Design considerations for plan development must incorporate parameters including contributing drainage area size, slope, flow velocity, vegetation characteristics and soil scour velocities. The success of non-point source drainage and erosion stabilization planning is based on implementing control measures that dissect drainage patterns, reduce flow velocities and disperse runoff towards sediment control sites. Interim and long-range drainage control measures should begin during exploration activities. Regulatory legislation addressing non-point source pollution sources was enacted as amendments to the Clean Water Act (CWA) in February 1987. The legislation required states to initiate non-point source pollution control programs.

Jan 1, 1991

By Anthony Delvescovo, Gregory F. Aluce, Joseph A. Sopko, Lyle C. Smith

Construction of a 13m shaft through approximately 100m of water bearing soils and another 100m of bedrock was attempted using the Slurry Diaphragm Wall Method with a combination of deep dewatering wells. During excavation within the slurry wall, unexpected groundwater inflows occurred in a structure of loose silty sands. Artificial ground freezing was selected as a remedial method to seal the leaking slurry wall, and as a primary excavation support and groundwater control method for the 30m of overburden material below the base of the wall. Design of the ground freezing system required analysis of both the structural requirements of the unsupported soil, the frost effects against the existing slurry wall and the groundwater control in the area of the breech in the wall. These design procedures are summarized, and construction and excavation techniques and corresponding schedules compared in this paper. Advanced drilling techniques, ground freezing quality control and general contractor procedures for efficient shaft construction are discussed.

Jan 1, 1993

By N. Lydakis ? Simantiris

Preliminary results of a mineralogical, geo-chemical and nutrient analysis of soil samples collected from Omalos polje-plateau are presented. This study is part of a project concerning the relationship of lithology and mineralogy characteristics of soils of different geological origin from the island of Crete with their chemical composition, and more specifically with their ionic nutrients content. The results presented in this work show a relatively good correlation of the mineralogy and the bulk content of the soils examined with the available nutrients in soil solution.

Jan 1, 2005

By Robert L. Bates

United States production of the industrial minerals, ahead of that of the metals since 1946, has shown a steady and rapid growth. By 1963, their value was more than twice that of the metals. Yet papers on the metallic ores continue to dominate the meetings of the Society of Economic Geologists and constitute nearly nine-tenths of the lead papers in Economic Geology. Most of the geological communication that does take place concerning the industrial minerals deals with high-value special-purpose minerals, which are comparable to the metallic ores in geologic complexity. The large-bulk rock products, which are growing fastest in production value, are characterized by relatively simple geology and by thousands of small producing firms, many of which do little or no geological work. The need for geological advice by this very large segment of the industry is bound to increase. In the meantime, a plea is made for more geological communication among those concerned with the industrial minerals of all varieties.

Jan 1, 1966