Search Documents

By S. K. Das

A detailed strata-mechanics investigation and examination was carried out in the E2 Panel (ML-II/7) of the XVI Bottom coal seam, which is located in the Moonidih Colliery of B.C.C.L., Jharia coalfield, India. Above this panel, the XVI Top coal seam was previously worked out by a longwall panel. Based on intensive field study and on experiments in a number of longwall panels located within various Indian coal mines, the actual behavior of the coal roof strata was evaluated and new strata-mechanics concepts around the longwall panels were developed. These concepts resulted in new methodologies concerning the behavior of roof rocks, caving characteristics, etc. within longwall panels and in the area of strata mechanics. Based on these new strata-mechanics concepts, a very simple, but realistic, model was developed to determine the optimum capacity of the powered supports. This model considered the combined loads resulting from the detachment of strata and composite layer blocks from the face and, also, loads due to the deflection of strata and composite layers situated above the detached roof rockmass. This formula, along with the other related formulas by the author, prompted the determination of the optimum capacity requirement for the powered supports to be used in the XVI Bottom coal seam, located under the worked out area. This new concept in strata mechanics and capacity requirements of the powered supports in a longwall face may be an aid to Mining Engineers.

Jan 1, 1997

By D. R. Lowe

Silicic volcanic ash and its alteration product, bentonite (montmorillonite and cristobalite), occur widely within sedimentary phosphate deposits. The genetic link, if any, between volcanism and phosphate deposition has yet to be satisfactorily established The phosphatic member of the Santa Margarita Formation (upper Miocene) in northwestern Ventura County, California, consists of approximately 15 per cent volcanic ash and bentonite. Ash and bentonite units greater than one foot thick can be subdivided into a lower zone of airfall origin and an upper zone of mixed ash and terrigenous detritus washed in from surrounding land areas. This upper zone also contains up to 20 percent phosphate pellets. These thick volcaniclastic units are typically overlain sharply by thin beds (less than 6 inches thick) of relatively pure, silica-cemented pelletal phosphorite. The shelf basin in which the phosphatic sediments accumulated was characterized by quiet, reducing but not euxenic bottom waters; Abundant decaying organic debris, mainly diatoms, served as a reservoir of readily available phosphate. The sudden influx of a large volume of silicic volcanic ash into this basin and its subsequent alteration to montmorillonite had two profound effects on thechemistry of the interstitial and bottom waters: (1) during alteration magnesium was removed from these waters and incorporated into the montmorillonite lattice, and (2) the pH of these waters increased as alteration progressed Both of these effects led to the crystallization in the bottom waters of carbonate fluorapatite. This accumulated as thin phosphorite beds immediately above the volcaniclastic units.

Jan 1, 1972

By Vicki Seppala

Phelps Dodge Mining Company operates some of the world’s largest open pit mines. Safely mining in these deep pits requires the commitment to a proactive integrated slope management process. The slope management process also includes the continued look for improved slope design, construction, and maintenance of slope faces. This paper discusses integration of such technology as electronic programmable detonators, 3D imaging using ground-based LiDAR scans, and reflectorless slope monitoring systems in a slope management program.

Jan 1, 2005

By A. E. Ketler

Powerful, yet inexpensive, personal computers running Windows-95 operating systems provide powerful mine-wide monitoring capabilities when properly engineered. Long awaited conductivity over LAN, phone and Internet links provide new dimensions for sharing information throughout an operator's organization, in- deed around the world. On-line data analysis, archival data storage and historical trend viewing generate shared inputs to production, safety and maintenance personnel. Five years in development, Rel-Tek's new EZ-Trol/W-DX system was engineered around the pilfalls of a Windows environment. It now offers higher speeds, 3D animated graphics and long distance telemetry - all with better reliability than ever before possible. The ubiquitous DDS utility inherent in most Windows was discarded in favor of a lightning fast RAM format. Several ponderous interpretive programs were redesigned into a single compiled entity, thus avoiding the overhead from message conversion, handshaking and transfer. To make the system user friendly, a 'Wizard" utility helps operators set up and reconfigure their systems on site. In-mine data acquisition telemetry was also re- vamped, incorporating a unique noise avoidance scheme, dubbed the "DX" bus - enabling longer distances and higher reliability. 12- bit analog conversion provides the enhanced resolution needed for field scaling auto-cal sensors. By mid '96, eight EZ-TROLMI- DX systems were up and running, several for more than a year. Factory updating and assistance are possible over a phone or Internet link. Our factory testing of components routinely includes actual operation at 2400 BAUD over 14 miles of twisted pair wires.

Jan 1, 1997

By Stephen G. Hardcastle

3D-CANVENT is a software package that integrates advanced computer aided design (ACRD) true 3D graphics with a mine ventilation simulator. The package runs as a Windows(tm) application to access its printer drivers environment and does not need third party CAD software. It is composed of two primary modules: DMVENT and MINEDESIGNER. DMVENT is a traditional Fortran coded Hardy-Cross iterative ventilation network solver written in 1980 with thermodynamic capabilities. This module is relatively unchanged with the traditional data input options for branch type, specified or calculated resistances, fixed flows, and fixed or variable pressure fans. MINEDESIGNER is the graphics engine that optimizes the ventilation design process. It performs the front-end transformation of input data entered in the graphical interface into the correct format for the solver. At the back-end it reconverts the historically standard tabular data output from the solver into an easily viewed graphical format. ACRD features of MINEDESIGNER are used to generate a 3D wire-frame node and branch network of the mine's ventilation system. The network can be displayed in up to 4 views orientated to XYZ planes or a 3D view. All the views have zoom, pan, slice and rotate options. The graphical interface efficiently permits data entry and editing via a mouse with pick-and-point item selection. Branches can be found or added with "search" and "join" options. Visual interpretation is enhanced by the 16 colour options for branches and numerous graphical attributes. Network locations are readily identified by alpha-numeric names for branches, junctions and fans, and also the logical numbering of junctions. The program is also readily expandable for pollutant simulation and control/monitoring applications.

Jan 1, 1995

By Herbert M. Mandel

INTRODUCTION Designers of major public works projects in the past have displayed varying degrees of environmental consciousness, and tunnel designers in particular have always had to deal with certain environmental considerations - ventilation, lighting, aesthetics - as matters of primary design. Today, however, with a widening sector of the public becoming environmentally aware, tunnels are treated as elements of whole transportation systems, and are subject to increasing environmental scrutiny. The Route H-3 tunnels in Hawaii are examples of the time, care, and detail involved in a major rock tunnel project. Project Description The Route. Interstate Route H-3 is a proposed 10-mile highway crossing the Koolau Mountain Range on the island of Oahu, Hawaii, providing a direct connection between the Pearl Harbor area and the windward part of the island in the vicinity of Kaneohe. It is designed as a dual highway with provision to accommodate mass transit. As shown on Figure 1, the project includes two sets of twin bore tunnels (through the Main Koolau Range and through Red Hill), three highway sections of which two are through largely undeveloped mountain valleys (South Halawa and Moanalua), a viaduct, and three interchanges. From the Halawa Interchange to the Kaneohe Interchange, the proposed highway consists of two 3-lane roadways separated by a median where the highway is at grade. One lane of each roadway will not be constructed initially but will be landscaped and reserved for mass

Jan 1, 1974

By Kenneth W. Torpey, James G. Ball, Richard F. Flanagan, David S. McAllister

INTRODUCTION Under a Federal grant by the Urban Mass Transit Administration (UMTA) (80%), and sponsored by the State of New York (200), Niagara Frontier Transportation Authority is constructing a 10.3 km (6.4 mile) light rail rapid transit system in Buffalo, New York. The $450 million project, which began construction in the Spring of 1979, is unique in rail transit alignment designs in the U.S.A. and the first predominantly underground light rail system in North America. The Buffalo project is unique in that the first phase of the expandable system follows the alignment of Main Street and is on the surface in a proposed 1.6 km (1.0 mile) pedestrian mall in the downtown business district. The alignment then progresses northward into a cut-and-cover portal and standard double-box configuration for 2.74 km (1.7 miles) at a depth of 9.1-10.7 m (30-35 ft) and subsequently drops into bedrock at depths of 18.3-27.4 m (60 to 90 ft). The 5.63 km (3.5 mile) rock tunnel section consists of two single tunnels 4.88 m (16.0 ft) nominal finished diam. and includes five stations. The rock tunnel line section was divided into a north and south contract of 2 316 m (7,600 ft) and 3 243 m (10,640 ft), respectively. Due to the existing surface facilities and the future station locations, the line tunnel contracts differed considerably in their shaft access

Jan 1, 1981

By R. C. Karra

Mining is one of the oldest profession and second after agriculture. Unfortunately Mining is not so familiar in the society. Due to lack of recognition in the society, existence of mines in remote places and in dusty and humid working conditions, led the poor response for mining engineering. Mining engineering programs have been increasingly less attractive to the student population over the years due to negative image of mining industry. After graduating in mining engineering, there is not much problem of employment at present. In the last 10 to 15years most of the mining engineering graduates have joined software industry. Even those joined in mining industry also left with in 2 years of service. The main reason for this is not being satisfied with job, it is not only working conditions but also work environment, work culture, remote location of the mines etc. Though many were trying to leave mining profession, the recent economic slow down has prompted some of them to incline towards job safety and retained to mining job. At this juncture a systematic study was taken up to analyze the job satisfaction of mining engineers in India.

Jan 1, 2011

By G. Wayne Clough

During shallow tunneling in an urban environment, deposits or pockets of saturated soil or fractured, weathered rock are often encountered. Under such conditions, special problems with tunnel support, underpinning of structures adjacent to the tunneling, and/or flow of groundwater into the tunnel occur. If the ground conditions are appropriate, i.e., the soil is sandy, silty or fissured, or the rock is weathered or fractured, the solution to these tunneling problems may be chemical stabilization of the ground. Injection stabilization as an aid to tunneling is practiced extensively in Europe and its use is increasing in the U.S. The advantages of this technique over conventional solutions can be substantial in terms of cost and time, especially in mechanized tunnel boring where even a small zone of soft ground can bring the tunneling to a complete halt. In this paper European practice in using chemical ground stabilization for urban tunneling will be reviewed. In contrast to previous papers which have dealt with specific applications (1,5,8,9) this paper will broadly cover the subject, addressing itself to grouting techniques, costs, the reasons for grouting, philosophy of the users towards grouting, design of grouting solutions (or lack thereof) and methods of quality control. Differences with U.S. grouting practice are also noted. The information presented is derived from several visits to Europe, discussions with European and U.S. grouting personnel, and the available literature (2). The author's most recent European trip was made under the auspices of the U.S. Department of Transportation in conjunction with a research study being performed at Stanford University; a detailed report of this visit is available in reference (6).

Jan 1, 1976

By L. J. Nicks

The current U.S. Bureau of Mines research program is addressing the recovery of flake graphite from kish, a steelmaking waste product, and the use of zeolites from abundant domestic natural deposits for efficiently cleaning up mining industry wastewater. The United States is almost totally dependent on imports for its graphite needs, but this may change depending upon the results from a pilot plant being constructed by industry using Bureau technology. Standard mineral processing techniques were applied by the Bureau to recover high-quality flake graphite from kish. It was considered innovative enough to receive an R&D 100 Award in 1992, and its commercialization has the potential to supply the total U.S. demands for graphite many times over. Zeolites have ion exchange properties similar to ion exchange resins, but are less expensive and available in large quantities. Samples of naturally occurring zeolites were tested for their efficiency in removing metal ions from synthetic and industrial waste solutions. The tests focused on defining their selecting, loading, eluting, and regenerating characteristics, and on developing a method for recovering the metal ions as added value products. The results showed that the removal of metal ions with zeolites from acid rock drainage (ARD) solutions is technically feasible and that this technique has the potential for being used in an integrated chemical treatment systems approach either as a primary or secondary cleaning step.

Jan 1, 1995

By James S. Scott

Effluents discharged from gold mills, and more recently from heap leaching operations, pose significant hazards to the environment if not properly managed prior to discharge. This paper describes the nature of wastewaters which must be treated, the treatment processes being applied in Canada and the capabilities of these methods in removing cyanide and metals. As a result of past practice the most common method of reducing cyanide in gold mill effluents remains that of natural degradation in tailings ponds. This method has proven capable of producing high quality effluents where large ponds and sufficiently long water retention times can be provided, but at many mines this has not been the case. Since 1981, as a result of these limitations there has been a strong move in Canada to chemically-based effluent treatment plants, particularly as additional processes became available. Canadian gold mills have become leaders in the use of chemical processes to remove cyanide, in terms of the variety of such processes in operation (five in total), the number of plant installations and the number of processes developed in this country. The hydrogen peroxide and Inco SO2-air processes, in that order, are being applied most widely. Alkaline chlorination, the initial process to be used fairly extensively has been almost totally replaced by the two methods mentioned above. Since a number of effective methods are now available for the treatment of gold mill effluents, the selection of a process for application at a specific mill requires careful consideration of:

Jan 1, 1987

By R. Y. Wan, J. D. Miller

Thiohydrometallurgical systems including thiosulfate, thiocyanate and thiourea have been stud- ied as alternative liriviants for the leaching of gold. Research and development of thiohydrometallurgical technology has been prompted by environmental concerns with the use of cyanide and problems associated with the processing of difficult-to-treat ores. These thiosystems have some chemical similarities, enabling gold to be leached in a practical oxidizing environment. However, the solution chemistry of the thiosystems is complicated due to instability of the thioreagents and many other reactions which occur during the gold leaching reaction. In this paper, interference reactions of selected metal ions and sulfide minerals are examined in order to understand important aspects of solution chemistry which control the stability of the thioleaching reactions. Applications using thioreagents as lixiviants for oxide and refractory gold ores are presented.

Jan 1, 2005

When exploration shows a mineral deposit to be of importance, the subsequent work of defining the limits or boundaries of the ore body and preparing it for the extraction of the mineral is termed development (Young, 1946). In underground mining, development also connotes the work that is involved in opening up a deposit preparatory to stoping or productive operations. In this section, mine development is defined to include all studies and operations that will enable a sound evaluation of an explored ore body from the technical and financial standpoints. Though the ultimate objective of all mine development activities is the same, the scope and detail of these activities vary depending on the type of ore body (e.g., flat bodies, lenses and sheets, massive deposits, narrow veins, and bedded deposits), and the method of working the deposit (e.g., under- ground or surface methods or a combination of both of the methods). Therefore, the various contributions in section 3 address such topics as long-range planning, feasibility studies, and valuation for many types of ore bodies and different mining methods. This introductory review is divided into three major parts. In the first part, long-range planning aspects are briefly discussed with .an emphasis on current trends that affect mine planning. In the second part, an overview is provided of the contents in the mine development and valuation section. In the last part, remarks are made on the status, scope, and future of quantitative and computer methods in mine planning and development.

Jan 1, 1979

By M. J. McPherson, P. Mousset-Jones, J. Banik, F. Calizaya

Friction factors or coefficients of friction used to estimate the resistances of mine airways are, in the main, estimated from empirical measurements made in other airways considered to be of a similar geometry and type of lining. A somewhat more analytical approach, although still based on empiricism, is to estimate the ratio of the average height of the asperities to the hydraulic mean diameter of the airway (e/D ratio) and then to employ the Moody Chart or one of the equations that have long been established to represent the [coefficient of friction v Reynolds number curves] on that chart. Unfortunately, the Moody Chart and corresponding equations are based on pipes of uniformly distributed (sand grain) roughness whereas the asperities that exist on the surfaces of mine openings are frequently highly irregular both in their size and distribution. This is considered to be a major cause of discrepancies that have been found between coefficients of friction by the Moody Chart and those actually measured in mine airways. The work described in this paper examines an alternative method of estimating coefficients of friction for rough natural surfaces with uneven sizes and distribution of surface asperities. The technique utilizes the relatively recent developments in fractal analysis. A fractal dimension is determined from the topography of the surface. This has been correlated to coefficient of friction for a scale model of a mine airway. Further work is being carried out in actual mine airways. However, at this time, it appears promising that the fractal method may allow coefficient of friction to be predicted for given types of strata and method of roadway drivage.

Jan 1, 1993

By J. Bigu

Ventilation conditions in working environments are usually studied by anemometry or, in complex cases, b using special tracer gases such as SF6 and 85Kr. in conjunction with chromatographic and radioactivity techniques, respectively. In some working environments, such as underground uranium mines, however, use can be made of the natural radioactivity environment (e.g.. 222rn. 220rn, and their progeny) to investigate mine ventilation conditions of practical interest. Theoretical studies and experimental data in several underground uranium mines and mine locations show that certain thoron progeny to radon progeny concentration ratios are very good indicators of ventilation conditions. Furthermore, the growth and decay of radon progeny and thoron progeny provide valuable information on mine air residence and clearance times. Some specific examples have been analyzed, such as bacterially-assisted uranium leaching operations in a partially enclosed stope, and the effect on the underground environment of turning ventilation fans on and off for a period of time. Air residence times and other variables of interest, determined from the mine radioactivity environment, were compared with more traditional techniques, such as anemometry and tracer gas chromatography. These studies were also extended to a wet non-uranium mine which exhibited relatively high concentrations of radon and its progeny.

Jan 1, 1989

By Pierre J. Wauters, Eddy J. Jacques

Starting up a fan or modifying its setting point either by rotational speed variations or blade angle changes, obviously results in new ventilation conditions in the network, which is, of course, the object of the operation. However, since transient phenomena may then occur, particularly in complex networks, there may be a need to simulate these situations prior to any action. This is all the more true, if we are dealing with a multiple interactive fan sys- tem. Simulations with a transient model have shown that the flow in certain airways could be temporarily reversed due to the pres- sure variations that reach both its ends with a different time lag. This phenomenon may cause dangerous situations to occur in cases of fire or outburst of methane. It is also true that the air flow could be reversed in secondary and less powerful fans, while still rotating in the normal direction. The study and the experimental investigation of the extension of the reverse flow characteristic is therefore justified from two points of view : • a numerical simulation model for transient flow conditions must be capable of handling temporary reversed flows, and thus have appropriate fan characteristic curves available over the entire operating domain; • while operating fans, reversed flows should be avoided or at least reduced. Therefore, the design of start-up procedures or real time control algorithms should take these phenomena into account. A particular interesting application is the operating of two fans in parallel. In order to investigate experimentally the characteristic curves of a fan under reversed flow conditions a small scale model was built. This facility was designed in such a manner that it was possible to carry out experiments concerning flow reversions and to try out sequential start-up procedures for two fans in parallel.

Jan 1, 1997

By William A. Dupree, Mark J. Schultz, William J. Francart

Maintaining intake escapeways clear of contaminants from mine fires has been an issue for many years. Removing fire sources from these entries reduces the risk of contamination greatly. In recent years, concerns have been raised related to contamination of the intake escapeways by leakage when fires occur in adjacent airways. This paper discusses measured leakage rates for multiple stoppings at various pressure drops across stopping lines in a number of actual coal mines. Also addressed are methods for reducing the contamination risks for the intake escapeways, considering the ventilation system employed. The Effects of Air Leakage The effects of air leakage through ventilation controls has been well documented. While normal leakage is expected through stoppings, overcasts and other structures, abnormally high leakage results in an inefficient ventilation system and can increase operational costs for a mine. In addition, excessive leakage results in less control over mine ventilation airsplits. This may compromise the isolation of mine escapeways, and allow adjacent entries to be rapidly contaminated by products of combustion in the event of a mine fire. A study was conducted at ten mines in which air pressure and quantity measurements were taken near the active sections. The method used to construct the ventilation controls to separate airways was also noted. Stopping Construction Table 1 shows the type of stopping construction commonly used in the 10 mines included in this study. Main entry stoppings were normally built with mortared joints (wet stacked) with sealant applied to the high pressure side of the stopping. In most cases the entire face of the stoppings were sealed. In one case only the joints between blocks were sealed but the perimeters were sealed in all cases. Some mines also sealed the low pressure side of the stopping. Solid blocks were normally used for main entry construction and hollow blocks were sometimes used for longwall panel development. [ ]

Jan 1, 1993

By Richard R. Radel, Jack Barry

Contract required excavating 2,000 If of 14' horseshoe tunnel in rock, a 95' deep work shaft on shore, and a 50' deep intake shaft located in the middle of the Niagara River just above Niagara Falls. Large quantities of H2S were encountered in the range of 20 PPM with ventilation. Peak levels of 40 PPM were recorded. The original designed ventilation system required only a volume of 10,000 CFM to meet OSHA requirements. The volume of air was increased to 50,000 CFM to dilute the H2S to al- low workmen to work and comply with OSHA H2S action levels. The second phase of the tunnel consisted of placing 72" ID X 20 foot long concrete reinforced pipe in the tunnel. When the tunnel was holed through and both shafts were open, a substantial amount of work was required to take place in the shafts which eliminated the possibility of placing a bulkhead to secure proper ventilation. The ventilation team designed a jet system airlock. The design of this system was to bring fresh air down the work shaft in two duct systems; one 30" diameter and one 24" diameter. Following the excellent work of Jan Wolski (7th Mine Ventilation Symposium chapter 58) our design incorporated nozzles located approximately 100' in by the work shaft. The velocity of the 24" diameter duct was 6,365 FPMD2.2 MPH. The velocity of the 30" diameter duct was 6,117 FPMl69.5 MPH. Both systems were on blow and being that air expands at 3112 degrees per side this high velocity of air expanded and created an air bulk head through which men and the large sections of concrete pipe could be passed without any delay or additional cost to the project.

Jan 1, 1997

By Barton Kelby Cross

In the early 1960's the feasibility of mathematical modeling was demonstrated in Northern Rhodesia and southwestern United States, where techniques were developed to use these models in a new approach to aid engineers in the estimation of ore reserves, mine designs, and financial evaluations. These rudimentary models closely followed the manual methods, producing ore reserves and production schedule estimates that were as accurate as the manual methods, yet were many times faster. Mines evaluated and designed using these new tools gradually came into operation during the 1970's and entered the phase at which production scheduling and ore-grade control became day-to-day problems. Management expected the number of operational engineers to be small because small planning engineering staffs had produced the original designs and operated the smaller high-grade pits. Unfortunately, the tools needed by the mine engineer to perform short-term production scheduling and ore-grade control were labor intensive; they had not yet been generally computerized. Several attempts to use the original or exploration model for these two functions were futile. While an exploration model based on data from exploration work proved sufficiently precise for overall mine design and long-term production scheduling, the model lacked the precision required for short-term scheduling and grade control.

Jan 1, 1979

By Andrew Mackenzie, Paul Rantala

Data is now appearing in literature that indicates many current paste fill systems in Canada suffer from plugged lines and severe wear rates. Both of these conditions suggest: design problems with the pipe distribution system, backfill composed of poorly graded material and/or possibly poor operator practices. Problems that can be prevented in the design stage, but still may be readily solvable with current technology. However, if left untreated will lead to an increasing frequency of down time. The compatibility of the distribution system with the paste fill rheology is fundamental and essential for the reliable delivery of fill. Either many mine operators are not familiar enough with the technology to provide a critical review that could foresee problems down the road, prior to construction and or North American designers are not clarifying their designs to their customers. The objective of this paper is to highlight key concepts to mine operators with the purpose of better enabling a critical review of contractor's/consultant's designs. There is a great deal of understanding about the rheology of backfill over a range of pulp densities from hydraulic slurry to dense to paste. However, outside of deep mines (especially in South Africa) neither hydraulic or dense fill distribution systems have suffered the problems of paste fill. Paste fill is fundamentally different from hydraulic fill principally in its transportation characteristics. These differences have a direct impact on the design of the distribution system. By understanding the practical implications of these differences the operator can play a more active role in their design while better appreciating how to best operate their own system.

Jan 1, 2001