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By M. Ramulu, A. K. Chakraborty, P. B. Sahu, C. Bandopadhyay, P. B. Choudhury

Human response to blast induced vibration and air overpressure is an unsolved problem that accompanies excavation process in mining. Pre-assessment and understanding of annoyance due to production blasting is probably one of the most important aspects of a successful mining operation. Complaints arising due to unoptimised blasts lead to various critical situations that hamper production. Inspite, this important aspect has been covered by a limited number of researchers in the world and probably least in Indian context. Human response is a complex phenomenon and the sensitivity of individual also vary from person to person depending on various factors like age, sex, literacy, health and exposure to mining. With ever increasing demand of minerals, opencast mines are expected to approach habitats and thus mine management may witness increased response to blasting. Many developed countries have their own guidelines based on scientific analysis, addressing such environmental problems, where as there are a few studies available in India. This study introspects above phenomenon in tune with mining requirements by analysing direct human response. This paper is based on a case study regarding the human response to blast induced hazards in a Manganese mine situated in central India. Advanced techniques of Critical Path Method and Multiple Response Analyses have been used to unearth important inferences on the response of different crosssections of population residing about the mine to blast induced noise, ground vibration and air overpressure. Various inferences drawn may provide guidelines to the planners, environment or safety departments and blasting official for safe and environment friendly blast design.

Jan 1, 2004

By S. Noh, T. K. Kim, B. O. Lee

Future nuclear reactor systems such as a sodium-cooled fast reactor are being designed under severe conditions in terms of operating temperature and irradiation fluence compared to current commercial reactors. For realization of such systems, it is necessary to develop an advanced structural material having both high strength and irradiation resistance at high temperatures. Oxide dispersion strengthened (ODS) steel is considered as one of the most promising structural material because of its excellent creep and irradiation resistance on the basis of uniformly distributed nano-oxide particles with a high density. Up to now, ODS steels have been intensively studied and developed to apply these materials to the in-core structural component of future nuclear systems. Several advanced ODS steels were designed and fabricated by a mechanical alloying, hot isostatic pressing and hot extrusion processes. This study focuses on the effects of heat treatment parameters during the fabrication process parameters on the microstructures of ODS steels for future nuclear system applications.

Jan 1, 2015

In 1960, the Secretary of the Interior, acting under the provisions of Public Law 454, 80th Congress, appointed a Lignite Advisory Committee to aid in programming research on coal (lignite) of the north-central area. The chairman of this committee is the Secretary of the Interior or his delegated representative, and in all meetings held during 1960 and 1961, the Director of the Bureau of Mines, Marling J. Ankeny, has presided. The members of this committee were R. W. Rovelstad, President, Baukol-Noonan, Inc., Noonan, N. Dak. W. E. Keller, Vice President, Northwest Division, Truax-Traer Coal Co., Minneapolis, Minn. A. M. Cooley, Professor of Chemical Engineering, University of North Dakota, Grand Forks; N. Dak.

Jan 1, 1963

By Oliver Bowles

ASBESTOS is a name applied to a group of naturally fibrous minerals. As indicated in a later section devoted to a detailed discussion of the early history of asbestos, the tern may be defined as a. fibrous form of serpentine or amphibole. It does not include fibrous forms of other minerals, such as wollastonite, nemalite (fibrous brucite), or the fibrous forms of calcite or gypsum. A material that has the characteristics of silk or cotton and at the same time will not burn is unique. Because it combines these qualities with other advantageous properties, asbestos has specialized uses for which no substitutes are yet available. Asbestos furnishes a major raw material for a great variety of essential products and their manufacture constitutes a vast industry. The United States leads all countries in the manufacture of asbestos products. The value of such commodities manufactured in 1952 exceeded $332 million. They are not only of vast importance to budding construction and industry but axe absolutely, essential to certain important fields of use, for example, steam packings and friction materials, such as brake-band linings on automobiles.

Jan 1, 1955

Combine the MSHA and OSHA versions of the HazCom Helper into one easy-to-use software tool.

Jan 6, 2007

By Grant R. Brown

The report provides guidance for determining those environmental impacts associated with the surface mining of steeply pitching coal seams. In addition to the environmental impacts, four additional issues are addressed, namely (1) Time and motion studies of those coal mining systems employed in mining seams which pitch in excess of 250, (2) Assessment of those mining techniques, (3) Development of rationale for the mining methods employed, (4) Identification of the reclamation practices and determine whether these practices were in compliance with appropriate Federal and State regulations. Five surface mines located in three geologically distinct basins of the United States were analyzed during the period of August through November 1979. The three basins include the Hanna Basin of Wyoming, the North Park Basin of Colorado and the Southern Anthracite Field of Pennsylvania.

Jan 1, 1980

By John Reilly

Costs of complex/underground projects have been consistently underestimated and delivery on time and on budget has been problematic. This has been attributed, to inadequate cost estimates and unidentified and/or insufficiently managed risk. Use of probabilistic cost estimates like the Washington State Department of Transportation?s CEVP® process (developed by the author and others) has produced more realistic cost estimates, explicitly identified and quantified risk (as input to risk management plans) and early awareness of key project issues. This paper updates previous work (NAT 2004), adds implementation detail for probalistic cost estimating as used by WSDOT, FHWA and other agencies and will address key issues in risk management, as related to probalistic cost estimates.

Jan 1, 2008

By A. J. Farstad

Electromagnetic location tests were conducted by Westinghouse Georesearch Laboratory under the sponsorship of the U. S. Bureau of Mines at the Galena Mine in Northwest Idaho. The objectives of these tests were to evaluate the performance in deep hardrock mines of an electromagnetic location system previously developed for the U. S. Bureau of Mines for use in coal mines. Tests were performed using long wire transmitting antennas as well as horizontal and vertical transmitting loops at depths from 3000 feet to 4300 feet (995 metres to 1311 metres). Surface measurements were made of magnetic field strengths, field strength patterns, and background noise, These measurements were compared with theoretical predictions for a homogeneous ground conductivity consistent with this particular geologic region. The results of the Galena Mine tests show conclusively that light-weight portable electromagnetic transmitters can be effectively utilized to provide uplink communications and location information in deep hardrock mines. Typical metal mines such as Galena utilize deep vertical shafts for mine access and haulage and these shafts produce signal enhancement at the surface from underground electromagnetic transmitters by as much as 30 dB. The results also show that horizontal wire configuration can serve as an effective alternative to the magnetic dipole antenna as a rescue transmitting antennaa and can be used when the required area is not available for deployment of a loop antenna. In spite of the electromagnetic coupling effects observed in the vicinity of the shafts, the location accuracy obtained still provided useful information on the general location of the transmitting sources involved. The horizontal wire location accuracy was within 46 metres, while the vertical magnetic dipole and the horizontal magnetic dipole accuracies were within 152 metres and 110 metres respectively at a 915 metre depth.

Jan 1, 1973

By Michael Murphy, Gamal Rashed, Brent Slaker

Pillar stability continues to be a significant concern in multiple-level mining conditions, particularly for deep mines when pillars are not stacked or the thickness of interburden between mining levels is thin. The National Institute for Occupational Safety and Health (NIOSH) is currently conducting research to investigate the stability of pillars in multiple-level limestone mines. In this study, FLAC3D models were created to investigate the effect of interburden thickness, the degree of pillar offset between mining levels, and in situ stress conditions on pillar stability at various depths of cover. The FLAC3D models were validated through in situ monitoring that was conducted at a multiple-level stone mine. The critical interburden thickness required to minimize the interaction between the mining levels on top-level pillar stability was explored, where the top level mine was developed first followed by the bottom level mine. The model results showed that there is an interaction between numerous factors that control the stability of pillars in multiple- level conditions. A combination of these factors may lead to various degrees of pillar instabilities. The highest degree of local pillar instability occurred when pillar overlap ranges between 10 and 70%. On the contrary, the highest degree of stability occurs when the pillars are stacked, the underlying assumption is that the interburden between mining levels is elastic (never fails). Generally, for depths of cover investigated in this study, the stability of top-level pillars shallower than 100 m (328 ft) or with interburden thicknesses greater than 1.33 times the roof span—16 m (52.4 ft) in this study—does not appear significantly impacted by pillar offset. The results of this study improve understanding of multiple-level interactions and advances the ultimate goal of reducing the risk of pillar instability in underground stone mines.

Jul 27, 2022

The work described herein is the opening phase of an extensive system of underground excavation undertaken under contract with a Malayan authority.The specifications called for the lining of all tunnels in earth or broken rock with circular segmented cast iron lining, similar to that of the London tubes, and it is the installation of these linings which it is proposed to discuss.Owing to the long deferred delivery quoted and the obvious need for speed of access to the internal installation, it was decided to defer driving the completed circular section and substitute two small timbered headings.These could later be opened out in turn to full section and lined without prejudice to traffic, since both of them had access to the internal workings.NATURE OF ROCKThe rock series through which the circular sections were driven consisted of:(a) A wide zone of intrusive porphyritic granite, consisting generally of orthoclase phenocrysts in a ground mass of micro pegmatite. This area showed advanced weathering, varying from a stage showing slightly tinted kaolin containing approximately 20% of small boulders to one of ultimate decomposition to pure kaolin;(b) A narrow zone of weathered augite diorite, consisting of rock masses of a maximum weight of some 100-150 tons, isolated by clay seams up to 1 ft. 6 in. in width.The whole area was in a state of quasi-hydrostatic equilibrium, which resulted in heavy pressure immediately after excavation. Freshly broken faces would appear to be quite solid but, within a few minutes, would commence to sweat and "slab off" under pressure and, unless support was placed promptly, the whole face would burst out and run from above. Mucking was slow, owing to the plastic nature of the clay and the ease with which it puddled into slurry.In zone (b) a good deal of trouble was experienced because of the fact that the somewhat heavy blasting necessary tended to cause movement of the large rock masses. Subsequent scouring out of the supporting clay bands by the waterflow permitted settlement of the ground on to the timbers and many reinforcing sets were therefore required.The timbering of the pilot headings and its relation to the cross-section of the circular tunnels is shown in Fig. 1. Top and side spiling was driven in the ordinary way, but in bad ground intermediate sets and breast boards had to be placed. These sets were usually withdrawn after the...

Jan 1, 1941

By Zsuzsanna Zborovszky

A circuit is considered intrinsically safe when any spark or thermal effect produced normally (that is, by operating the equipment in its correct operational manner to fulfill its purpose) or accidentally (caused by short circuit, earth fault, defective components, breaking the wiring, etc.) is incapable under prescribed test conditions of causing ignition of a prescribed gas mixture. The test conditions and gas mixture should be at least as hazardous as the true parameters of the environment where the circuit will be operated. According to present practices, the question of whether or not a circuit is intrinsically safe is decided upon experimentally. The circuit is inspected first for mechanical soundness and a survey is made to determine what faults should be considered as probable. Then the individual branches are connected, in sequence, to a test apparatus called 'breakflash" which acts as an opening, closing contact and thus draws sparks from the circuit. This test is repeated a given number of times in the presence of the prescribed gas mixture under specified conditions (electrode configurations, gas parameters, etc.). The equipment will be regarded as intrinsically safe if during testing no ignition has occurred.

Jan 1, 1972

Newmont?s Twin Creeks Mine, located in northern Nevada, is producing gold ore from surface mining operations. The ore is currently processed at three different on site facilities depending on the ore type and the grade. The processing facilities operate under stringent geochemical blending constraints that must be met from mine ore deliveries and off site sourced ore. To analyze various strategic options, the technical team utilizes the mathematical optimization approach. However, due to the size and the complexity of the operation, there are unique challenges in optimizing life of mine production scheduling. This paper describes those challenges and the methodology developed to take advantage of different scheduling software systems that effectively compensate each other and result in reasonable guidance. The paper also describes how those scheduling results are reflected in detailed mine plan and cost estimate work.

Feb 27, 2013

By John D. VandeKraats

Yielding rock bolt support systems have been developed to accommodate ground movement in shifting ground such as in coal operations; in creeping ground such as salt, trona, and potash; and in swelling ground associated with some clays. These systems, designed to remain intact despite ground movement, should enhance mine safety and help contain costs in areas where rebolting of rigid non-yielding systems is typically required. Four such systems were tested in straight tensile pulls in the laboratory. They include the Slip Nut System from Dywidag Systems International USA, Inc., Ischebeck's bolt mounted Titan Load Indicator, Rocky Mountain Bolt Company's Yielding Cable Bolt, and a rock bolt installed variation of the yielding steel post developed by RE/SPEC Inc. The first two systems are currently marketed products and the latter two are prototype systems. Each system responds to load and displacement by yielding in a unique manner. All are designed to yield at predetermined loads. A description of each system and its yield function is provided. Each system was tested over its prescribed yield range in a test machine. At least five tests were performed on each system. Each system yielded and continued to provide support according to its design. Each shows promise for ground control use in shifting or creeping rock. This work helps to illustrate the comparative differences in performance between these specialized systems and the applications where they may be most useful.

Jan 1, 1996

By Ke Yang

Drilled shafts are widely adopted as the foundation for sound walls. However, there has been a lack of uniformity in design and analysis methods and design criteria, in terms of factor of safety against ultimate capacity failure as well as the allowable deflection. In order to establish a uniform design methodology for the drilled shafts supporting sound walls in cohesive and cohesionless soils, respectively, a database of full-scale lateral load tests on fully instrumented drilled shafts was collected. Based on the compiled database, existing design methods and design criteria of laterally loaded drilled shafts were evaluated. Broms method and COM624P (or LPILE) are suggested as the design methods for drilled shafts supporting sound walls in both cohesive and cohesionless soils. Additionally, the corresponding design criteria, including factor of safety and permissible deflection, for both design methods are recommended. Two full-scale lateral load tests on fully instrumented drilled shafts were subsequently conducted in Colorado to further verify the design recommendation. A comprehensive geotechnical investigation program was also carried out at the two new lateral load test sites that included pressuremeter test, SPT, as well as laboratory triaxial consolidated undrained tests and direct shear tests on the soil samples taken from the lateral load test sites. The test results obtained at these two load test sites were employed to validate the recommended geotechnical design and geotechnical testing methods for the drilled shafts supporting sound walls.

Jan 1, 2007

By T. R. Wildeman

"At the Big Five wetland, which was built to treat drainage from a metal mine, encouraging results have attributed to sulfate reduction. Cu and Zn were reduced to below detection limits of 0.50 mg/L, Fe was reduced by at least 90% to below 3 mg/L, and the pH was raised from below 3 to above 6. The study showed that treatment was primarily through microbial processes within the substrate and that plants were not needed to insure success.Constructed wetlands can be taken through design and proofing stages, and into operations scale in a meaningful time frame for on-line acid drainage remediation. In staged design, laboratory experiments are initiated to determine reasonable substrate materials for remediation of a particular drainage. When a reasonable substrate is found, bench scale experiments are initiated as the next stage in the design. In these studies, removal efficiency, permeability, and flow are analyzed to identify candidate substrate which will support sulfate reduction and be hydraulically reasonable. Using this design method at one site, an acid drainage of pH 2.5 was raised to a pH of above 7. Total heavy metal concentrations in this drainage exceeded 900 mg/L. In the pilot constructed wetland Cu, Zn, and Fe were reduced by 99%.Determining how well these anaerobic cells operate in the winter is done at the pilot plant site in Idaho Springs, CO. It's been found that over the last four winters, those cells that emphasize anaerobic removal within the substrate have operated continuously and effectively the year round. Winter operation is aided by the fact that the water temperature of the acid drainage is always between 14 and 16° C, and the cell can be readily insulated from the cold. Activity of the sulfate reducing bacteria may decrease during the winter. However, it appears that organic complexation of metals helps to maintain low concentrations of metals in the effluent."

Jan 1, 1992

By Verya Nasri, Mehdi Bakhshi

"Fiber reinforcement has emerged as an alternative to steel bars in precast concrete segments due to advantages such as saving cost and reducing production time while developing a more robust product with improved handling and long-term durability. ACI recently drafted a new report as the first design guideline on FRC tunnel segments to provide specific guidance for this emerging technology. ACI document offers general information on the history of FRC precast segments from tunneling projects throughout the world; a procedure for structural analysis and design based on governing load cases, and a description of the material parameters, tests and analyses required to complete the design. This paper summarizes the design considerations in this ACI guideline prepared by the authors of this paper as the main contributors. Application of this guideline to design of a tunnel with an internal diameter of 5.5 m (18 ft) results in elimination of steel bars.INTRODUCTIONPrecast concrete segments are installed to support the tunnel excavation behind the Tunnel Boring Machine (TBM) in soft ground and weak rock applications. The TBM advances by thrusting off the completed rings of precast concrete segments that provide both the initial and final ground support as part of a one-pass lining system. These segments are typically designed to resist the permanent loads from the ground and groundwater as well as the temporary loads from production, transportation and construction. Tunnel segments are generally reinforced to resist the tensile stresses at both the Serviceability (SLS) and the Ultimate Limit States (ULS). With traditional rebar, a significant amount of labor is needed to assemble the cages and place the rebar, which results in higher production costs.Fiber Reinforced Concrete (FRC) can be used to enhance the production, handling, and placement of precast concrete segments. This is because of the uniform dispersion of fibers throughout the segment to include the concrete cover, which is very advantageous for resisting the bursting and spalling stresses. These stresses develop as a result of the high loads induced on the segments during the TBM jacking process. The presence of fiber in the concrete matrix helps mitigate against unintentional impact loads during segment handling and tunnel construction operations."

Jan 1, 2016

By Jerry C. Tien

China?s remarkable levels of economic growth during the past three decades have lifted almost 300 million people out of poverty. This amazing achievement has placed an increasing demand on energy and minerals, especially coal, which supplies 68.7 percent of China?s energy (June 2011). It is estimated that China mined more than 3 Gt (3.3 billion st) of coal in 2010, three times as much when compared to merely 10 years earlier. Such an impressive achievement does not come without major costs ?? including concerns with mine safety and an increasing number of occupational illnesses due to fast growth. This article reports on one of the major safety concerns in China?s coal mining, dust and dust control practices, and known cases of caol worker?s pneumoconiosis affiliated with prolonged exposure to excessive coal dusts. The exact size of China?s mining industry is not known, but it is estimated the coal industry is at least five-million people strong, and the metal and nonmetals industry probably employs another three million people. To meet increasing energy demand, China mined more than 3.1 Gt (3.4 billion st) of coal in 2010 from its 15,000 plus coal operations1, most of which are small- to medium-sized operations with annual coal productions ranging from a few thousand tons to 300 kt (330,000 st). These small coal operations are typically in remote areas, inadequately engineered, poorly ventilated and still using rudimentary drilling and blasting mining methods employing antiquated mining equipment and, presenting safety concerns, i.e., methane and dust explosions.

Jan 1, 2011

By H. Laitala, M. Lampi

Metso Outotec has developed a wide range of solvent-extraction technologies over decades and has introduced Metso Outotec VSF®X solvent-extraction plant. Standardized and modularized, Metso Outotec VSFX Plant provides a novel way to design, manufacture, transport, install, operate, and maintain solvent-extraction plants far better than in the past with highly sustainable and safe methods. For the customer, this means fast-track projects with savings in means of time, costs, quality, and operation. Sicomines and Metso Outotec have together implemented and commissioned a modern and efficient copper solvent-extraction plant. Plant commissioning and ramp up of the plant were fast and the plant is now operating efficiently. This paper presents Sicomines’ VSFX copper solvent-extraction project and gives a sight into operating figures for the plant.

Jan 1, 2023

By Joseph D. Davis, GEORGE S. POPE

This bulletin is the fourth of a series a showing the results of the purchase of coal by the Government under specifications. The work of inspecting and analyzing coal delivered on Government contracts was transferred to the Bureau of Mines by an act of Congress effective July 1, 1910. It had been carried on for several years before that date by the technologic branch of the United States Geological Survey. The purchase of coal on the dealer's statement as to quality or on the reputation of the mine or district producing the coal is gradually being discontinued. At present most coal-purchasing contracts make definite provision regarding the desired heating value of a coal and the composition as shown by analysis. The heating value is usually expressed in British thermal units" and the composition specified is that shown by proximate" analysis. The price to be paid for delivered coal is made to depend on whether the analyses and heating-value tests of samples representing the delivery show the quality to be above or below the quality set forth in the contract. Large coal consumers are beginning to appreciate more and more the importance of the cost of power as a factor in the cost of producing a finished article. The endeavor to increase the efficiency and the economical operation of a power plant calls for an intimate knowledge of the quality of the coal being used. The purchase of coal under specifications insures the purchaser getting what he pays for and the coal being of the quality guaranteed. In addition, the analyses and tests of the delivered coal furnish data whereby the power-plant results can be comprehensively studied and a continuous check maintained on the conditions of operation.

Jan 1, 1912

By H. L. Hazen

THIS is the story of the recent operations of the Standard Cyaniding Co., which owns the Standard mine, a low-grade gold property in sight of Highway 40 about thirty miles from Lovelock toward Winnemucca, Nev. The ore is mined by power shovel and cyanided after grinding to only 3/S in. A total direct cost of $1.24 was attained in 1941 on 600 tons a day. Mining operations ceased, under Government edict, in 1942, and only in recent months have been resumed. The operating difficulties of today are: (1) the high cost of supplies; (2) labor problems; and (3) Federal laws as interpreted and enforced by executive bureaus of the Government. Of these, the increased cost of supplies is the least important.

Jan 1, 1947