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By Ali Ameli

Design loads are limited for piles relying upon toe stresses in rock due to uncertainty about the rock quality over the whole pile diameter because of rock mass properties or construction effects. The paper discusses the use of video images to evaluate rock quality at the bottom of piles socketed into graniodorite bedrock in a steel pipe pile project. Skillful interpretation was required to assess the 3D properties of the rock from video images. It is necessary to observe the rock mass characteristics near the project site for better perception of the rock features from the images. Video image interpretation skills were established by the evaluation of the cores drilled under the socket base and the results of pile loading tests. Correlations were found between rock appearance in the images and the rock socket drilling records. Rock socket acceptance criteria were developed through monitoring the drilling operations for the specific site procedures. Video images then served as one of the quality-assurance tools together with probing and pile loading test. Lessons and methods learned from video inspection in this project could be used to evaluate rock quality in similar cases.

Jan 1, 2006

By K. L. Whitehead

An examination of 60 mines, 11 illumination hardware manufacturers, and Q mobile face-equipment manufacturers was conducted to determine the state of the art of mine-illumination hardware, define lighting system installation and maintenance problems, and assess personnel acceptance of lighting. Longwall and mobile face-machine illumination were studied. Major problems on room and pillar installations include damage of exposed components, electrical failures, and reduced lamp life, with extreme variability in the degree of these problems. Most longwall systems had low or moderate maintenance requirements, cable damage being the most significant problem. Most mobile face-equipment operators liked their machines' lighting systems, but many complained of glare and other problems. Longwall lighting was unanimously accepted by face personnel, and most complaints were minor. Based on the survey, general installation and maintenance guidelines have been established, addressing hardware design aspects, approaches proved effective to minimize problems, and improper practices noted which are detrimental to effective lighting.

Jan 1, 1981

By Michael G. Pojar

This Bureau of Mines report estimates the population of the principal types of machinery in use by the coal mining industry during 1982 in surface and underground mines. Estimates were arrived at using 1976 coal equipment population estimates as baseline data with modifications made for new mine development, expansion, and closure occurring during 1976-82. Estimates were broken down into 3 regions which included all 26 coal-producing States. Modifications made to the baseline data were computed using (1) actual equipment information when available, plus (2) equipment information hypothesized from representative generic mine models, which were predicated on mine size and mine method. Roughly half of the equipment fleet at new or expanding coal operations was known; the remainder was hypothesized. The mine models used to generate equipment information are included in this report, along with the hypothesized equipment use data. The equations and various factors used to determine the equipment adjustments for mine closings, new mine openings, and small coal mine operations are also identified.

Jan 1, 1986

8186. Aquilina, C. Determinazioni relative di gravita eseguite nel 1939 (Relative Determinations of Gravity Made in 1939), Ric. Ingegn, Rome, vol. 10, 1942, pp, 6376. In 1939, the author made a survey of relative gravity in the Mediterranean-basin, 41° 35,5' to 41° 56.3' northern latitude and 0° 10,3' to 0° 28' longitude, referred to Mt. Mario. Ten stations were covered; 25 other stations had been occupied in the vicinity of Rome and in Albanian mountains during previous years. The new measurements revealed gravity anomalies ranging within the following limits: (1) With a free-air reduction, between + 29 and + 120 mgl., average + 60 mgl.; and (2) with a Bouguer reduction, between + 22 and + 87 mgl., average + 41.5 mgl. - V. S.

Jan 1, 1946

By E. R. Palowitch

Coal wasted with mine refuse represents losses in overall recovery of merchantable coal to the mine operator and a concomitant reduction in domestic reserves of available coal. Fraser, Kelley, and Graham3/ in studying the available coal in mine refuse in the Pittsburgh district of western Pennsylvania have estimated that at least 1 ton of mine refuse is produced for each 10 tons of merchantable coal and that 20 percent of this mine refuse might be recovered as salable coal by mechanical cleaning. SUMMARY This investigation dealt with the mechanical recovery of coal from wine refuse by a dense-medium washery employing pulverized mine rock as the dense medium and operating at a rate of 175 tons per hour. Two types of mint refuse were tested: Freshly mined and that .which had been mined 2 years before and piled on a waste dump.

Jan 1, 1955

Demonstration of Solid-Liquid Separations Using Recycled Supernatant that Contains Temperature-Responsive Polymer The effective use of recycled supernatant that contains temperature-responsive flocculant is demonstrated for solid-liquid separations. The recyclability of poly(N-isopropylacrylamide) (PNIPAM) of several different molecular weights and a 15 per cent negatively charged derivative are compared. Batch settling tests of a-alumina suspensions are first conducted at 50¦C, with a subsequent 25¦C period, after which the supernatant is harvested and used to flocculate subsequent suspensions. Using this procedure consecutive separations are obtained with the repeated recycling of uncharged PNIPAM containing supernatant. Batch settling tests indicate that hindered settling rates increase with molecular weight of PNIPAM. Adsorption studies indicate that strong adsorption of PNIPAM onto alumina occurs with PNIPAM at 50¦C and that significant desorption occurs after cooling at 25¦C. However, the extent of desorption decreases with molecular weight resulting in low amounts of PNIPAM for recycling and poor settling behaviour when high molecular weight PNIPAM is recycled. Little recyclability was evident using the negatively charged PNIPAM. On the basis of these findings a recycling-thickener apparatus that uses low molecular weight uncharged PNIPAM is proposed.

Sep 13, 2010

By Ted Nye

This paper describes a number of aspects of the design and construction of a driven tunnel which forms part of the Boggo Road Busway project. The driven tunnel is 430m long with an excavated width of 15m and a full tunnel excavation height of 8m. The first section of driven tunnel was excavated under the heritage listed Boggo Road Jail for a length of 120m. The main jail buildings and perimeter walls were built in 1908 and are of brick construction. Ground cover over the tunnel beneath the jail site varied from 5.5m to 8m and as a consequence the predicted settlement values and their potential to cause damage to the buildings were critical to determining and obtaining approval for the selected tunnel alignment. The geology along the driven tunnel alignment was very variable, providing mixed face tunneling conditions and ranging from surface residual soils to high strength rock at depth. The maximum ground cover above the driven tunnel is 20m.

Maps To Accompany Bulletin 418

Jan 1, 1941

The use of solid state detector and radioisotope x-ray source for x-ray fluorescence analysis is illustrated by analysis for iron, copper, zinc, tin, and lead in about 700 samples taken from Australian mineral process streams. Limits of detection based on counting statistics (3 standard deviations) range from 0·001 to 0·004 per cent by weight element. The analysis accuracy was usualIy between 2 to 10 per cent (rms) of the mean element concentration and was determined by comparison with assays supplied by mineral companies. In most cases the main cause of error appears to be due to this assay and not the x-ray fluorescence technique.Some potential fields of application of solid state detector and radioisotope x-ray source for analyses in the mineral industry are indicated.

Jan 1, 1974

By R Yang, M Lownds

This paper reports studies showing the effects of delay scatter on the peak particle velocity (PPV) of blast vibration using a multiple seed wave (MSW) vibration model developed in recent years. The case studies also show the advantage of accurate delay timing on frequency control of blast vibration. The site parameters used in one of the studies are from a case in which the MSW model has been tested and confirmed to yield accurate predictions. This study uses an open pit blast design and a tunnel design in which blast vibrations using electronic detonators are compared with those from pyrotechnic detonators. Mean peak particle velocity (PPV) and the 97.5% upper bound PPV are compared. It is found that both these values increase significantly with the increase of the coefficient of variation of the site parameter. Using an open pit blast design, the modeling shows that electronic initiation shifts vibration energy to the expected frequency for a selected point of interest. However, for the same design of nominal initiation timing pyrotechnic detonators fail to shift vibration to the expected frequency due to its large scatter of timing.

Jan 1, 2011

By Gabriel S. Esterhuizen, Jarek Jakubec

In 2000, Laubscher’s Mining Rock Mass Rating (MRMR) classification system was updated and published. The new system brought a few fundamental changes that were in direct response to the challenges and problems encountered when applying the classification system in the mining environment, specifically caving operations. The fundamental changes introduced into the MRMR system in 2000 were the abandonment of the Rock Quality Designation (RQD) as an input parameter, accounting for healed and cemented joints, and the concept of rock block strength. The objective of this paper is not to discuss the role and usefulness of classification systems; the fact that classification systems are widely used in every stage of mining projects speaks for itself. This paper discusses some of the experiences gained with the MRMR 2000 system in various mining projects and shows how the changes to the system have resulted in improved assessment of rock mass conditions. Issues related to core logging for rock mass assessment are also presented.

Jan 5, 2007

By C. Özgen Karacan

The formation of the gas emission zone in longwall mining and the potential amount of gas in this zone are factors of local geology and spatial variability within this geology. Therefore, geostatistical methods can be used for modeling and prediction of gas amounts and for assessing its uncertainty in the gas emission zone of longwall mines. This study used core data obtained from 64 exploration boreholes drilled from the surface to the bottom of the Pittsburgh coal seam in a mining district in the Northern Appalachian basin. After identifying important coal layers for the gas emission zone, semivariogram modeling was conducted for different coal seams to define the distribution and continuity of various attributes. Sequential simulations were performed for stochastic assessment of these attributes to calculate gas-in-place (GIP) in each coal seam. GIP calculations for coals of various gas emissions zones were combined and ranked for their cumulative distribution function to find GIP in the caved zone and in the fractured zone at the 5%, 50%, and 95% quantiles. Fifty percent quantile results were later used to isolate a panel from the whole area and create a mosaic representation corresponding to the daily advance rate of the longwall face. This approach helped to estimate the daily emissions of this panel from the caved zone and from the fractured zone. Results showed that gas-in-place in the Pittsburgh coal seam, in the caved zone, and in the fractured zone showed spatial correlations that could be modeled and estimated using geostatistical methods. This study showed that gas-in- place volumes in the study area may be as high as 12.3 Bscf and as much as 3.5 MMscf per acre of mining.

Jan 1, 2012

By P. Mark. Hawley

Development of Barrick Gold?s Pierina Gold Mine in north-central Peru requires construction of a waste dump for disposal of non-ore grade materials stripped from the open pit to expose the ore. The waste dump site is located near the open pit in a U-shaped valley that is underlain by thin colluvial and morainal soils with locally thick peats and glaciolacustrine deposits. Bedrock underlying the site consists of variably weathered volcanics. The site is subject to moderately high seasonal rainfall and significant seismicity. The geotechnical quality of the waste rock is highly variable, ranging from low quality, degradable, soil-like materials containing appreciable quantities of silt and clay, to high quality, hard, durable, blocky waste rock. A hybrid dump design concept was developed that requires in-pit segregation of high and low quality waste, and selective placement of materials in the dump to maximize stability and enhance internal and subsurface drainage. The design includes a rock drain beneath the dump along the axis of the valley and a series of connected finger drains. Extensive peripheral diversions and stormwater control measures to inhibit infiltration of precipitation are also included. This paper discusses the unique challenges presented by the site and waste materials, the design methodology and stability analyses, and planned monitoring systems.

May 1, 2002

By W. W. Adams

The extent to which coal mines have installed various types of haulage systems and mining machines is a subject about which there is little definite information available in convenient form for the country as a whole . A few State mine inspectors include in their annual reports such information for their respective States , but uniform data for the United States have not until recently been compiled . Several years ago the Bureau of Mines compiled from one of the standard mining directories * a statement showing the kinds of machines and haulage used in coal mines . The first statement was prepared from the 1918 edition of the directory in which detailed descriptions of coal mines were given . The information presumably related to the calendar year 1917. Similar statements have been compiled from the directories for 1919 , 1920 , and 1922 , the statement for 1921 having been omitted because the directory for that year did not become available . The latest statement is given below and is based upon the directory for 1922. It relates to conditions prevailing in 1921 , and covers a total of 7,088 coal mines . Of these , 5,064 mines . or more than 71 per cent , were using animal haulage . As compared with the total number of all classes of mines , those in the animal - haul age group constituted 71.4 per cent , the percentage having remained practically stationary during the past four years , although the actual number of mines in the group has increased . Rope haulage was reported by 1,066 mines , or 15 per cent of the total , representing a larger number of mines than in 1918 , but a decrease of 2 in the percentage for the group as compared with all classes of mines . Electric haulage was reported by 3,274 mines (46.2 per cent ) , and the number of motors in use was 11,265 . The percentage of mines in this class has not changed materially, but the actual number of mines has shown a gain of about 900 during the past four years . Compressed-air locomotives have not increased either in actual or relative number , the percentage for the past year being but 1.2 . The number of mines using storage- battery locomotives has increased from 3.6 per cent of the total shown four years ago , to 9.8 per cent for last year, the latest figures showing 693 mines with 1,428

May 1, 1922

By Drupad B. Desai, Bruce Chang, Jay L. Merritt

This paper reviews difficult ground conditions encountered along the alignment of large-diameter sewage tunnels for the City of Los Angeles. It offers a detailed one-of-a-kind solution to a unique problem for shallow urban underground tunnels in a seismic zone, using state-of-the-art materials, technology, and equipment. The following topics are discussed in detail: • Geotechnical Design consideration for tunnel traversing through an active fault zone. • Seismologist evaluation of possible fault-offset problems where a fault zone crosses the alignment, in the event of an earthquake of moment-magnitude 6.5. • Probability analysis regarding "recurrence interval." • Structural design of tunnel subjected to displacement, subjected to axial elongation or shortening, and capable of rotational freedom. • Special joint details.

Jan 1, 1989

By Armando Gallegos Monteagudo

El presente texto señala las experiencias realizadas en GERENS, empresa de consultoría y capacitación en gestión del sector minero, formulación, implementación y control de planes estratégicos que utiliza herramientas con un alto nivel ambiental en la creación de valor económica, ambiental para las empresas mineras el Balanced Scorecard (BSC) y el análisis de la cadena de valor de la empresa. El Balanced Scorecard es una herramienta gerencial que apoya la implementación del plan estratégico y permite su monitoreo y control. Para ello, el BSC requiere que el plan estratégico de la empresa se traduzca en objetivos claros y medibles, indicadores, líneas de base, metas, y programas de acción estratégicos y tácticos.

Sep 12, 2005

The Wainui Mill was conceived as a 60 - 90 t/d central mill to process gold ores of the Thames area of New Zealand from small mines in the district. The ores of the region exhibit various degrees of refractory response to conventional cyanidation leach due to the fineness of the gold, and association with pyrite. The alternative circuits involving cyanidation, flotation, and possible small-scale smelting are examined. The environmental impacts have been audited by the Commission for the Environment and were found to be acceptable.

Jan 1, 1986

By John P. McDonnell

Cable supports offer several advantages over traditional secondary support methods by enhancing stress redistribution to pillars and gob areas, minimizing or eliminating timbers and cribs that reduce ventilation, eradicating material-handling injuries related to placement of crib supports, and providing a cost-effective alternative to secondary support. The U.S. Bureau of Mines, in researching alternatives to traditional roof support methods, designed and installed high-strength cable supports to improve the stability of longwall gate road and bleeder entries in a Western U.S. coal mine. With the cooperation of industry, methods were developed to install cable supports in a tailgate and bleeder entry test area using traditional resin cartridges. Resin-grouted cable bolts were also installed and evaluated in additional longwall gate road and bleeder entry systems at the study mine. The cable-bolted areas successfully maintained roof support throughout the tailgate and bleeder entries. Cable supports replaced wood cribbing as secondary support in the bleeder entry system and minimized the use of cribbing in the longwall tailgate entries. This report describes the theory, application, and advantages of cable supports and presents mine measurements made to assess the cable performance during the retreat process of longwall mining.

Jan 1, 2010

By JeffreyS. Vipperman, Daniel R. Babich, EricR. Bauer

In response to the continuing problem of noise induced hearing loss NIHL among mine workers, the National Institute for Occupational Safety and Health NIOSH has conducted numerous noise surveys in coal preparation plants. The research, consisting of worker dose monitoring, task observations, and equipment noise profiling, was completed in eight separate preparation plants. Worker dose monitoring was conducted for three shifts in most cases. Workers experiencing higher than allowable doses were task-observed for one full shift to correlate dose to noise source(s). Finally, noise levels on all floors, and in lunchrooms and control rooms, were characterized. Results indicate that only workers who routinely spend a significant portion of their shift in the plants (away from the control rooms) are susceptible to overexposure from noise. Certain pieces of equipment (screens, centrifuges, sieve bends) are the loudest primary noise sources responsible for the worker noise exposures.

A combined reflection seismic and magnetic survey off the south coast of New South Wales has revealed six distinct reflection horizons within the Lower Triassic-Upper Permian sequence, and has enabled the upper part of the lllawarra Coal Measures to be mapped in considerable detail. Large magnetic anomalies in the eastern half of the survey area appear to originate in the Gerringong Volcanic Sequence which forms the magnetic basement in the survey. Small residual anomalies in the western half of the area can be correlated with small scale faulting and folding in the upper part of the llawarra Coal Measures, as revealed by the seismic reflection survey.A synclinal axis striking at approximately 55° has been mapped near the western margin of the survey area, and areas of faulting and folding have been outlined by combined analysis of seismic and magnetic results.

Jan 1, 1970