Search Documents

By T. S. Mohibatsela, R. V. Ramani, C. V. Manula

The Mineral Engineering Department of The Pennsylvania State University has developed a suite of computer models for anthracite open pit mining (Fig. 1)1 Individual sub-systems have been developed to (a) interpolate geologic field data to obtain coal tonnages, waste volumes, and strip ratios; (b) simulate equipment performance on selected pit profiles to generate data required to choose coal and waste removal equipment; and (c) evaluate selected cost factors to determine either a rate of return for a specified selling price or vice-versa. This paper describes the application of two of these subsystems, namely, the Reserves Model (GEOL) and the Open Pit Materials Handling Simulator (OPMHS), and how these may be applied for the selection of equipment for a prime anthracite mining site.2

Jan 1, 1981

By Owen S. Roberts

During the design phases of a conveyor system, the question arises regarding the type of drive required for each application. The paper shows that the correct drive for any particular application is the one that satisfies the criteria established for that application in the most economical manner consistent with such considerations as site location, availability of spare parts, area environmental conditions, power supplies available, etc. Following discussions of various mechanical arrangements for the drives, motor types and their characteristics are considered along with the control means of modifying these characteristics to satisfy individual requirements. These characteristics are all illustrated graphically. After selecting the motor and its starter, control accessories and interlocking arrangements as applied to material handling systems are discussed.

Jan 1, 1973

By Smith KS

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralized areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado, has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles (1) could have been better utilized to first predict and minimize the environmental problems, and (2) can now be used to optimize the environmental cleanup.

Jan 1, 1995

By Earle J. Klohn

Mining operations have been carried out in British Columbia since the time of the first settlers in the area. The early developments were mainly small volume, high-grade operations, producing small quantities of tailings wastes. In these early days the nearest stream was a logical first choice for tailings disposal. Where streams suitable for accepting the tailings were not available or where streams crossing the International Border could not be used for this purpose, the nearest convenient land site was selected for storing the tailings. Old tailings waste piles exist at many locations in the Province and are readily evident, for example, in the Princeton and Hedley areas. Figs. 1 and 2 are photographs showing the present condition of two of these old tailings dams. [ ]

Jan 1, 1972

By P. James, L. J. Steiner, F. Turin

NIOSH researchers and an industry partner conducted an investigation to study the effectiveness of ergonomic interventions in mining. The study required a significant commitment of time and resources from the cooperating site, Bridger Coal Company. This paper focuses on some of the challenges faced by the researchers and their cooperator. Challenges included the need to redesign methods of identifying and prioritizing injuries, and the need to train the workforce in ergonomics while still maintaining progress and interest in the process. The authors discuss some practical interventions implemented by Bridger Coal to date, and discuss future research implications brought about by PacifiCorp’s Generation Business Unit, who monitored the project to determine whether an employee-owned ergonomic process could be implemented throughout their operations.

Jan 1, 2003

By Wilson Blake

A mathematical model based on the finite element method of stress analysis has been used to describe the behavior of the western wall of the Kimbley Pit as its slope was steepened from 45 degrees to 57 degrees. Theoretical stress changes because of slope modification are slight except at the toe of the modified slope. Magnitudes of stress created are small when compared with the strength of a competent rock. Resulting displacement patterns point out the need for determining the in situ state of stress at a site prior to excavation or modification. A comparison of model results with field measurements shows that, in general, the model has described the measured behavior of the west wall of the Kimbley Pit remarkably well.

Jan 1, 1968

By Charles A. Maliszewski, James M. Galvin, Gerhard Urschitz

With obvious signs of deterioration, the double track, historically registered Bergen Tunnels as part of the commuter rail system in New Jersey waited for rehabilitation for a long time. Serious water in filtration not only caused operational and safety hazards for the electrified rail line but also deteriorated and structurally compromised the tunnel lining. An innovative rehabilitation program was developed to enlarge the tunnel and to provide a new waterproofing system and final lining. For the rock excavation and support New Austrian Tunneling Method (NATM) principles were utilized, while water tightness was achieved by installing a PVC membrane waterproofing system followed by a reinforced cast-in-place final lining. Experienced on-site supervision generated additional savings during construction by streamlining support elements based on geologic conditions encountered.

Jan 1, 2003

By Sullivan T. D, Lohe E. M

Geological structure is one of the main controls on ground conditions within mining. It has a significant impact on the mining conditions and productivity of coal mines within the Sydney - Bowen Basin. The three main types of faults common to this region, normal, reverse and strike-slip systems, each present distinct challenges to mining. These systems effect a wide range of geotechnical and mining conditions within the mines. These include coal quality, strata stability, goat and caving behaviour, productivity and maintenance schedules of mining equipment, mine design and mine-site stress fields. A better understanding of the regional, local and mine-scale structural setting, timing relationships of structural events and the mechanisms of fault formation will greatly aid industry's push for greater productivity and competitiveness.

Jan 1, 1991

By Robert L. Runkel, D. Kirk Nordstrom, James W. Ball

Low-flow reactive-transport processes in Wightman Fork downstream of the Summitville Mine, south-central Colorado were simulated using the OTIS and OTEQ solute-transport models. The simulation was calibrated using data from a synoptic study conducted during October, 1998. Discharge over the 8-km reach from just below the mine site to the Alamosa River confluence ranged from 0.077 to 0.17 m3/s; travel time was 10.7 hours; pH ranged from 4.6 to 5.7. Simulations revealed that mass balance for SO4 was maintained, and that pH, Fe, and Al were non-conservative. Simulations allowing hydrous ferric and aluminum oxide or hydroxysulfate precipitation matched observed water quality conditions more closely than simulations without precipitation.

Jan 1, 2000

By Prohaska G, Jackson F, Jack B

To learn more about the fundamental roof behaviour in South African coal mines, accurate underground measurements of roof deflection were conducted in bord and pillar panels during development and pillar extraction. To conduct these measurements a survey levelling technique was adapted. The overall system reading accuracy was established as being within 0,4 mm on a 15 m sighting distance. The underground sites were modelled and, for a roadway development, similar symmetrical curvatures were calculated by a linear elastic model, as were measured underground. In a pillar extraction panel, a significant amount of bed separation was measured and the roof underwent an a-symmetric movement due to the close presence of the mined out area at one side of the roadway.

Jan 1, 1992

By Huamin Li

Mine # 8 of Pindingshan Coal Group, Henan Province, China has an annual production 2 million metric tons. But it encounters many problems, e.g. mine layout is complicated, roadway maintenance is difficult, coal and gas outbursts are severe, production cost is high, etc. The major reason was due to the additive effects of abutment pressure interaction of previous mining in D, E, and F seams. At the request of mine management, an in-depth systematic analysis including underground observation, modeling with simulated materials, and photoelastic experimentation was performed to obtain site-specific results which include the dynamic and static influence zones of mining D, E, and F seams, propagation characteristics of abutment pressure in the floor strata, interburden movement caused by undermining, etc.

Jan 1, 2000

By André Vervoort

To learn more about the fundamental roof behaviour in South African coal mines, accurate underground measurements of roof deflection were conducted in bord and pillar panels during development and pillar extraction. To conduct these measurements a survey levelling technique was adapted. The overall system reading accuracy was established as being within 0,4 mm on a 15 m sighting distance. The underground sites were modelled and, for a roadway development, similar symmetrical curvatures were calculated by a linear elastic model, as were measured underground. In a pillar extraction panel, a significant amount of bed separation was measured and the roof underwent an a-symmetric movement due to the close presence of the mined out area at one side of the roadway.

Jan 1, 1992

By Courtney Black, Paul F. Ziemkiewicz, Eberhard Werner, Matthew Daly, Joseph J. Donovan, Jeff Frazier

Injection of alkaline waste-lime slurry was performed at a West Virginia surface coal mine site, to attempt neutralization of acid springs by an alkaline recharge method. Deep trenching (>5 m) using an excavator yielded the most effective injection into the aquifer. Water from two springs, 90 m from the deep trench, showed 70%-80% reduction in acidity in response to injection. Neutralization persisted >170 days after treatment, with pH between 5.1-5.7 and metal acidity from 25-60 mg/L. A minor fraction of lime introduced was consumed. The sustained neutralization is attributed to reaction of acid water with subsurface lime, entrained below the wafer table by macropore infiltration. Characteristics of groundwater transport are critical in determining recharge structure location.

Jan 1, 2000

By Mictck Rataj

Methods of rock reinforcement in Australian coal mines are being advanced progressively through the better understanding of rock failure mechanisms around roadways and the-development of improved bolting hardware and installation techniques. It has been recognised that to improve the performance of rock reinforcement systems, the stiffness of the system as a whole has to be improved. New style bolts and accessories together with high pre-tensioned roof and cable bolts are being developed as a result. A number of the new techniques used to stabilise the roof, especially in weak roof/high horizontal stress areas have been site proven and are now currently used on a routine basis as a means of improving development rates and gate road stability during longwall retreat.

Jan 1, 1997

By Grouhel P

Blasting performance is directly related to the characteristics and efficiency of the explosives used. The selection of the correct explosive for particular blast conditions and objectives depends on the ability to characterise the performance of individual explosive products. Techniques have been developed by the JKMRC to measure explosive performance and assess the impact of explosive performance on blast results. Studies conducted at a number of mine sites have shown that different types of explosives perform quite differently and that the performance of any particular explosive can vary significantly. The principal causes of these variations have been identified and detailed blast monitoring techniques, including the analysis of muckpile fragmentation and shape, have been used to quantify the effects of explosive performance on blast Results.

Jan 1, 1990

By W. N. Marchant

The Bureau of Mines improved removal of selenium from zinc smelter acidic gas scrubber effluent by using zinc dust to precipitate soluble selenium prior to lime neutralization. Lime neutralization alone decreased selenium in the waste water from, typically, 6 parts per million to 2 parts per million, whereas the use of zinc dust precipitant gave an effluent containing less than 0.1 part per million of selenium. The waste treatment operation first was developed on a laboratory scale and later was successfully tested at a smelter site on a 1-gallon-per-minute basis. During the research a simple and rapid means was developed for determining selenium in waste water; the technique enabled visual semiquantitative selenium determinations that later were confirmed quantitatively by X-ray fluorescence.

Jan 1, 1978

Mining had a very considerable effect on the country's development. The visual evidence remaining is an integral part of New Zealand history. Early mining for manganese and copper in the 1840s was succeeded by alluvial gold rushes. These gave way to hard rock extraction, hydraulic elevation and dredging. Coal mining dating from the 1850s was fairly widespread. Other minerals were obtained on a small scale. Manufacture of mining' machinery stimulated industrial engineering enterprises. Schools of mines played a significant part in advancing technical skills and several remain as museums. Surviving mine structures and site relics are part of the industrial heritage signifying the technological and economic development of a small isolated nation. Some of these are described. Identification, recording and preservation where practicable is advocated.

Jan 1, 1990

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which are 8 to 12 feet in diameter and extending over 200 feet in depth below grade. There are unique challenges associated with constructing such large and deep cast-in-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

Jan 1, 2013

By D. A. Swanson

Predicting when and at what rate seepage will occur from waste-rock facilities is becoming an integral part of permitting and closure at mines situated in dry climates. Such predictions require development of a conceptual framework that accurately describes how water will percolate through a waste-rock facility. Also needed is a detailed hydrological characterization of the waste-rock facility, including measurement of the hydraulic properties of the waste rock and any potential cover materials. This paper presents a conceptual framework describing unsaturated water flow in a waste-rock facility and describes methods for characterizing the hydrology of a waste-rock facility in a dry climate. The methods are designed to collect site-specific data to support accurate and defensible predictions of long-term seepage rates.

Jan 1, 1998

By M. V. K. Reddy

A differential flotation process for recovery of molybdenite from chalcopyrite concentrates produced at Rakha Copper Concentrator, Bihar, India has been developed. The flowsheet is simple, and relatively inexpensive and yields a concentrate assaying not less than 45% Mo at a recovery of minimum 65%, starting from chalcopyrite concentrate assaying 0.4% Mo. The consumption of the main depressant used, sodium sulphide is not more than 25 kg/t of copper concentrate processed without steaming; and with steaming the consumption was brought dorm to less than 12 kg/t of concentrate. Further reduction is possible by optimization of steaming parameters. Based on laboratory experimental results, further tests were conducted on concentrator site and process design parameters were established for design of commercial plant.

Jan 1, 1982