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By Russell J. Miller

A high-pressure intensifier system was designed, constructed and field tested as part of a program to determining the feasibility of applying high-pressure water jets on conventional mechanical rock excavation equipment to increase advance rates. Also developed were a high-volume swivel, capable of transferring the high-pressure water to a rotating cutterhead and manifold system for locating and protecting the jets on the cutterhead. Field tests were conducted in a granite quarry near Skykomish, WA, approximately 90 miles east of Seattle. The concept of improving excavation rates by using water jets to assist mechanical cutting was proven to be successful, with an average increase in excavation mete of 50 to 60%. For some tests, the excavation rate was more than doubled. Machine torque requirements were reduced approximately 25% when the water jets were used. It was suggested this was due to reduced cutterhead friction in the presence of the water jets. A comprehensive economic analysis was undertaken as part of a concurrent study to determine the degree of cost benefits attainable from increased advance rates. Very significant savings were seen to be possible. It was concluded that the basic concept of combining a water jet capability with a mechanical excavating machine is definitely possible.

Jan 1, 1976

By D. A. Reynolds

[A few studies on the relationship of the fusion temperature of the ash of coke to that of the corresponding coal have been made on commercial high-temperature cokes. R. J. Rose3/ in 1921 compared the' fusion temperatures of the ashes of 10 coals and. the cokes produced from them and concluded tat they were in such close agreement that either figure could be used. More recently, Quarfort4/ found that the ash of coke fused at a somewhat lower temperature than that of the original coals As the ash of a coal and that of the coke produced therefrom have the same origin their chemical composition should be identical, provided that carbonization has not altered the inorganic, or ash-forming, constituents of the coal, and such alteration seems highly improbable. However, it has been shown5/ that coke is liable to contamination by iron during crushing and preparatory to sampling. Pieters6/ found that coke ash was cantaminated in this manner up to 0.4 percent. extraneous iron would lower the ash-fusion temperature because such iron may form ferrous silicate, which is readily fusible,7/ These results provide a basis for the prediction that the ash of coke will fuse at a lower temperature than that of the corresponding coil., especially if the fine grinding of the coke was done by rubbing surfaces of iron, as in a disk pulverizer or bucking plate.]

Jan 1, 1940

By A. Patri, D. S. Nimaje

Wireless sensor networks and wireless communication systems have become indispensable in underground mines. Wireless sensor networks are being used for better real-time data acquisition from ground monitoring devices, gas sensors, and mining equipment, whereas wireless communication systems are needed for locating and communicating with workers. Conventional methods like wireline communication have proved to be ineffective in the event of mine hazards such as roof falls, fires etc. Before implementation of any wireless system, the variable path loss indices for different workplaces should be determined. This helps in better signal reception and sensor node localization, and also improves the method by which miners carrying the wireless devices are tracked. This paper proposes a novel method for determining the parameters of a suitable radio propagation model, which is illustrated with the results of a practical experiment carried out in an underground coal mine in southern India. The path loss indices, along with other essential parameters for accurate localization, have been determined using the XBee modules and ZigBee protocol at 2.4 GHz frequency.

Jan 1, 2015

By F. S. Kendorski

This report presents the results of a search for viable-self-drilling roof bolt concepts, detailed development, design, and manufacture of such bolts that drill their own holes, and testing in the laboratory and in the field in two different coal mines of three self-drilling roof bolts. Three new types of bolts were designed and tested, which drill their own holes and then anchor in continuous operation. These were a spring-actuated mechanical expansion shell, a slot and wedge, and a self-contained resin anchor bolt. Such bolts when fully developed for mine use would allow safer and remote installation of ground support and increase productivity. Recommendations are given for further work to improve drilling and anchorage performance.

Jan 1, 1979

By G. M. Steed, A. O. Oyinloye

The deposit lies in amphibolite-facies biotite granite-gneisses of Proterozoic age, 4 km east of a major crustal break known as the Ifewara-Zungeru fault. Gold mineralisation is contained in a zone of quartz-carbonate (mainly calcite) veins and hydrothermally altered gneisses with associated small-scale intrusions along a steeply dipping second-order fault zone that roughly parallels the main fault. Gold is present mainly at grain boundaries between quartz and carbonate as discrete particles up to 100 micrometres in size, in general association with sparse, scattered pyrite, pyrrhotite and some base metal sulphides. Adjacent to the gold-bearing zone the granite-gneisses have been hydrothermally altered with minor volume increase, most notable enrichment being in K2O, S, Pb and Cu (and Au). High concentrations of Th, Y, Ce and Zr in the granite-gneisses imply derivation from S-type granites. It is likely that their high heat production capacity maintained the high temperatures needed to transport gold in the hydrothermal systems. It is most probable that the mineralisation dates from the Pan-African orogeny (650-450 Ma)

Apr 1, 1996

By A. J. MOORE

When the writer first saw the square-set timbering, he was at once impressed with the fact that the frames made by the sets, along the lode and across it, were composed of panels with rectangular openings, and it was puzzling to understand howsuch a collapsible construction could resist pressure that came unevenly on it. Later he learnt that the sets did not satisfactorily resist such pressure, but mullock filling had, to a great extent, to undertake this duty for them. So it appeared that the setswere practically an expensive scaffolding, enabling the miners to work in the face and carry the stope forward, till the filling was put in behind them to take the pressure of the roof and sides of the excavation. Of course some of the pressure is takenby the sets, but this is because "the set timbers prevent the filling being done perfectly; if it were practicable to remove the sets before filling, the filling by itself would more effectively support the back and wall, than do the combined sets andmullock. On the whole, therefore, the sets can hardly be said to be of much benefit where pressure has to be resisted. Despite this, the system has been of immense service in mining wide lodes, but for all that, it can only be pronounced a makeshift.This is no reflection on Deidesheimer, the famous originator of the square set, for, as will be shown later on, this way of...

Jan 1, 1912

By R. L. Grant, R. W. Van Dolah, N. E. Hanna

An experimental investigation was conducted to assay the relation between natural gas concentration and ignitibility of the gallery atmosphere . Both the gas concentration representing maximum ignitibility and the relationship between certain properties of the explosives and their incendivity are discussed . The data show that variation in the natural gas content in the gallery can have a highly significant effect on ignitibility of the gallery atmosphere ; maximum ignitibility of the atmosphere by permissible explosives occurs with approximately 8.1 percent natural gas . The study also shows that incendivity of a permissible explosive cannot be determined only by its detonation velocity , oxygen balance , or ballistic mortar strength . However , for similar type explosives , trends observed indicate that their incendivity increases with detonation velocity or bulk strength . Additionally , for underoxidized explosives studied here , the more negative the oxygen balance the less incendive was the explosive within a class defined by salt content .

Jan 1, 1963

By Edward A. Barrett

The ability to recognize visual cues commonly associated with roof and rib hazards is fundamental to the prevention of groundfall accidents. The perceptual skills that miners possess to visually search and assess hazardous ground conditions differ considerably. This U.S. Bureau of Mines report summarizes recent investigations on the use of stereoscopic (3-D) slides as a training aid for improving the ability of miners to recognize the various geologic and mining-induced irregularities that cause ground-falls. The feasibility of using 3-D slides for training and their effectiveness for representing roof and rib hazard conditions are discussed. Information is presented on equipment and procedures for creating a 3-D slide program that can be updated by mine trainers. Recommendations are made on selection of 3-D equipment and on the use of 3-D slides for training miners to recognize roof and rib hazards.

Jan 1, 1988

By R. R. Faddick

Properties of coal-water slurries were studied in two separate phases: a rheological phase and a pipeline phase. The purpose of the study was to investigate the rheology of fine coal slurries to determine the effect of fine particles in a coal-water mixture on the economic and operational aspects of a slurry pipeline. The slurries consisted of 6x10, 100x200, and 200x0 mesh coal in water. A fourth slurry consisted of a mixture of the 6x10 and 200x0 mesh coal. Brookfield and Stormer rotational viscometers were used to obtain or simulate rheograms for a range of fine coal concentrations, temperatures, and particle sizes. All the slurries were pumped through a 1-inch diameter acrylic pipe. The fine coal slurries were found to encompass four distinct rheological models. The narrow size distribution of the coal slurries was apparently responsible for the high pipewall friction losses, more so than the particle size. A scale-up method applicable to Bingham plastics was found satisfactory for predicting pipeline headlosses of fine coal slurries from rheology data.

Jan 1, 1974

In a previous paper the writer dealt -with the jasper bar formations and their relationship to the structural geology of older pre-Cambrian rocks in the goldfields districts of Western Australia (24). He has pointed out in this ahd other papers that jasper bars, or banded iron formations, banded hematite or ,magnetite quartzites, jaspilites and related banded ferruginous or non-ferruginous cherts, occur in abundan'ce in the Older Greenstone Series of Western Australia (22), (24), (26). They are considered to represent special forms of banded ferruginous sediments, and are usually fpund in the field interbedded with more or less metamorphosed pasaltic 01' andesitic lavas and tuffs, now amphibolites, together with occasional thin bands of normal pelitic sediments, which go to make up a large proportion of the Older Greenstones in thfs State (26).Great thicknesses of fiat-bedded ]:landed ferruginous cherts are also found associated with cherty' carbonate rocks; quartzites, shales and thin-bedded dolomite whicIi constit'ute the Nullagine (Pl'oterozoic) system in the northwest of Western Australia. In the Hamersley Range district these banded ferruginous chert beds are the hosts of important deposits of blue amphibole asbestos.In the paper mentioned above brief reference was> made to the importance, of geological structure in relation to economic geology, particularly in the goldfields regions of Western Australia, and it was shown that jasper bars may have an important role in the study of 'the structural geology of many of these regions. Of possibly more immediate economic importance is the part that these rocks play, both directly and indirectly, as host rocks for mineral deposits-the chief of Which are gold, iron ores, blue asbestos, and manganese ores. The blue asbestos bearing banded iron formations mentioned above are confined to the younger pre-Cambrian Nullagine formations. They have been described in detail elsewhere (23). In this paper it is proposed to discuss the economic geology of the jasper bars found in the older pre-Cambrian series.The jasper 'bars have in themselves little or no intrinsic value except perhaps some of the more highly coloured and banded varieties which may be utilised for ornamental and decorative purposes. Probably the best known of such varieties is the so-called "marble bar;" a belt of, strikingly coloured banded chert occurring just south and west of the famous town of that name (see Fig. 1t). This consists of a hard, very fine, even-grained rock with alternate individual stripes varying from the thickness of a sheet of paper up to an inch or more in width, and ranging in colour from clear white to yellow, from various shades of pink to brilliant...

Jan 1, 1943

By J. D. Bosman

The problems associated with squeezing rock conditions in tunnels are well known and have been extensively investigated in the past. Although squeezing conditions are predominantly found in tunnels developed in weak rock types it has been noted at the No. 6 Shaft of Hartebeestfontein Mine where the host rock consists of hard, brittle quartzites. This paper investigates typical time-dependent deformation mechanisms in the rock at Hartebeestfontein Mine. The paper will focus on observations made in a strike-orientated tunnel that intersected weak quartzite layers, that were sandwiched between two competent quartzite beds. The observed squeezing mechanism is dominated by creep along bedding planes with a soft talcaceous infilling that behaves in a clay-like fashion when saturated in water. Stress-induced deformation processes, some distance into the sidewall of the excavation, force the already fractured periphery of the excavation into the void. A laboratory study of the creep of intact rock and discontinuities collected at this site was conducted to characterize the time-dependent behaviour. The difference in creep rates between the two types of quartzite found at this site is described in the paper. Creep tests performed on the talcaceous infilling material found that its presence allows substantial shear creep along discontinuities. Attempts were also made to simulate the squeezing mechanism observed underground with numerical techniques. Due to the discontinuous nature of the mechanism described above, a viscoplastic displacement discontinuity technique was used as it allowed for the explicit simulation of discontinuity creep. The results of the modelling and how it compared with the observed behaviour are described in the paper. Environmental impact statement The work described in this paper will not cause any new, or contribute to any existing, hazards confronting the environment.

Jan 1, 2000

By K. Yamaguchi, Sekimoto. H.

"Platinum Group Metals (PGMs) used as catalyst which reduces toxic substances in emission gas exhausted from an automobile should extensively be recycled because they are rare metals produced only at the limited regions. The recycling process is to smelt an alumina honeycomb, in which PGM is built, in molten iron with flux such as lime and silica to separate them. PGMs are concentrated in molten iron while alumina in slag.The objective of this study is to understand the factor to concentrate PGMs in liquid iron as much as possible. Fundamental research of the distribution of the PGMs between the slag and liquid iron was carried out to recover the value metals of platinum, palladium and rhodium from the three-way auto catalyst. The distribution ratios of platinum, palladium and rhodium between the Al2O3-CaO-SiO2 slag and liquid iron are from 10-6 to 10-5, and these are concentrated in comparison with slag phase by about 1 million times to the liquid iron at 1873 K. The distribution ratios of platinum between the FexO-CaO-SiO2 slag and liquid iron decrease from 0.1 to 2?10-4 with increasing the CaO content in the slag. The CaO addition to the FexO unary slag is effective in concentrating platinum in molten iron.Based on the distribution ratios obtained in this work, recovery of PGMs was determined. The recovery of platinum, palladium and rhodium increase with increasing the mass ratio, Mmetal/Mslag. In the case of the conditions of Mmetal/Mslag = 0.04, the recoveries of PGMs showed more than 99.97%. The use of liquid iron and carbon saturated liquid iron as the collector metal is advantageous for the PGM recycling of the three-way auto catalyst. We found that PGMs are enriched to the molten iron or the carbon saturated iron and the slag loss of PGMs is negligible small."

Jan 1, 2014

By J. A. McLennan

Nickel laterite deposits are typically formed from tropically weathered mafic-ultramafic complexes. The resulting nickel concentration is found within soil horizons and is mineable with regular dozer units. At the time of mining, digging elevations are needed at selective mining units (SMUs). Moreover, for mine planning, the costs due to dilution and lost ore require mining elevations to be specified. A conditional simulation approach is used to calculate ?optimum? SMU mining elevations. Multiple realizations of the ore base surface are simulated. For a single bottom surface realization, dilution and lost ore costs are calculated over the entire vertical extent of each SMU. The optimum mining elevation is the elevation where the lowest summed cost of ?accepting dilution? and ?wasting ore? occurs. The reported SMU dilution is the cost of mining the volume of waste located below the bottom surface and above the optimum mining elevation and the reported SMU lost ore is the cost of not mining the volume of ore above the bottom surface and below the optimum mining elevation. For all ore bottom surface realizations, optimum SMU mining elevations and their associated dilution and lost ore costs are calculated and compiled to represent production uncertainty.

Apr 1, 2005

By Oliver Bowles

From remote antiquity stone has been employed for structural, ornamental, and memorial purposes. It was, and still is, so used because of its availability in innumerable localities and its architectural adaptability, dignity, substantiality, and durability. The principal varieties of stone used are granite, marble, limestone, sandstone, and slate. This report deals with granite. OCCURRENCE AND CHARACTER OF GRANITE Granites usually have been classed as igneous rocks derived from molten masses or magmas, but there is wide evidence that the origin of some granites may be attributed to regional metamorphism of preexisting rocks, rearrangement and recrystallization taking place without a liquid or molten stage. In any event granitization is a slow, deep-seated process.

Jan 1, 1956

By Michael S. Kucker, Stuart Warren, Robert A. Robinson, Michael J. Lehnen, David McAllister

Geotechnical conditions exposed by the phased exploration programs have had a major impact on the selection of excavation and support methods, dewatering requirements, size of openings, vertical alignment, and estimated cost of construction for the Beacon Hill Tunnel and Station section of the “Link” Light Rail. Beacon Hill is comprised of a very complex glacial geology, including numerous slickensided fractures, injected sand dikes, and multiple perched groundwater levels as revealed by a phased boring program and exposed in a test shaft. The Geotechnical Baseline Report (GBR) presents this complex geology along with a “tool box” of alternative additional support systems to accommodate the varying ground conditions during construction of the station excavation. Additional explorations will also be accomplished during construction to further refine the geotechnical interpretations and provide an opportunity to use pro-active ground improvement techniques to optimize the station excavation and support requirements.

Jan 1, 2005

By Maya Kamenetsky, Khoi Nguyen, Natalee Bonnici, Steve Walters, Claire McMahon, Julie Hunt, Ron Berry

"The analysis of meso- and micro-scale textural attributes has been undertaken on ore samples from the Ernest Henry iron oxide-copper-gold (IOCG) deposit in NW QLD. Quantified textural data including grain size, shape and mineral association have been extracted from classified images of core with the aim to better predict potential mineral processing behaviours such as comminution, liberation and flotation. Data have been extracted from images of intact core at meso- and micro-scales using high resolution continuous images collected using automated core-logger technology, SEM-based and optical microscopy platforms.The results of this study will show examples of quantified size, shape and mineral association data from meso- and micro-scale classified images. Analysis of the data shows that there are domains of variable grain size and mineral association that can potentially be related to crushing and liberation behaviour. The trends that are observed at the drill-core (meso-) scale are consistent with those at the micro-scale. The results from the micro-scale analysis show that the domains defined at the core-scale have clearly different chalcopyrite sizes and shapes as well as variable bulk mineralogy.INTRODUCTIONInnovations in technology have allowed automated extraction of information about mineral shape, grain size and mineral association, i.e., texture, from meso- and micro-scale images of intact rocks. The overall aim of this research is to investigate trends in quantified textural data that can potentially give an early view of processing parameters such as predicted grind size and liberation behaviour."

Jan 1, 2009

The largest investment in mining equipment in Caterpillar?s history ? The F series mechanical and electrical drive trucks ? is rapidly advancing. Caterpillar showcased the 793F and 797F mechanical drive trucks and the 795F ac electric drive truck at MinExpo in 2008 and have continued testing since then. The 793F and the 797F have accumulated more than 75,000 hours of field testing and have proven their performance capabilities and their durability. The new Cat C175 engine that powers them has racked up 130,000 hours of field testing in mining trucks and more than 120,000 hours in power systems. Because of the success of these field-follow programs, the 793F is targeted to go into full production within a few months and the 797F late this year. Caterpillar engineers have been testing two 795F ac prototypes at the Tucson Proving Grounds in Arizona. The development program has provided input for the construction of a new 795F ac in Decatur, IL. The new truck recently shipped to a copper mine in North America where it will serve as the first field-follow 795F ac as it works at the mine. The 313-t- (345-st-) capacity 795F ac will enter a new size class for Caterpillar, and, as a result, the primary focus of the Caterpillar ac electric program has been on the 795F ac. The commercial launch date will be defined as the field-follow program progresses. ?It?s fitting that soon after producing the 50,000th Cat off-highway truck, we are now shipping our first ultra-class ac electric drive truck to a mine,? said Chris Curfman, president of Caterpillar Global Mining. ?Our new trucks further solidify our position as the one manufacturer to provide unparalleled options and unmatched customer support.?

Jan 1, 2009

By Lester J. Crow

This study advances the use of elemental sulfur in structural materials by demonstrating its value in bonding high-strength, well-graded basalt aggregates to form sulfur-basalt concretes. Sulfur is an excellent bonding agent, and the strength of a thermoplastic sulfur-aggregate mixture depends, to a large degree, on the strength and grain-size distribution of the aggregate used. A 3-cubic-foot, electrically powered mixer with heat applied to the barrel was used to mix the sulfur and aggregate. Sulfur content of several mixtures was varied to obtain the best workability with a minimum of sulfur in excess of that necessary to fill the voids. The average grain sizes and grain-size distributions were also varied to determine their effects on strength. Unconfined compression tests of forty-five 6-by l2-inch cylinders yielded average strendths of 3,348 psi to 10,398 psi. The highest strength single cylinder was 10,717 psi. The cylinders were tested from 24 hours to 6 days after pouring; after 24 hours the rise in strength was very slight. From the results obtained it appears that sulfur can be a useful construction material. An evaluation was made of a high-vacuum application for sulfur concrete. Sulfur has a high vapor pressure at elevated temperatures, 50° to 100° C; consequently, significant losses by sublimation can be expected. At lower temperatures the losses are not significant; however, this factor will limit its use at a higher temperature.

Jan 1, 1970

By L. Kulik, J. den Drijver

Rhenish lignite will continue to play an indispensible role in the energy mix of the German Federal Republic for a long time to come. The use of lignite for electricity generation, upgrading and, if necessary, as a raw material is geared to the long term. The holistic management of opencast mines underpinned by approval law in the long term and a stronger focus on man, the environment and nature contribute to the acceptance of the mines by the local population. The same is true of state-of-the-art lignite uses: as regards their operational flexibility, lignite-fired power plants are ideal partners for the expansion of renewables. It is along these lines that RWE is continuing its power plant renewal programme as planned. With a view to that which will be conceivable the day after tomorrow, RWE is researching future technologies today in order to meet objectives such as security of supply, profitability and environmental compatibility to the same extent in the long term. Another important contribution to acceptance is public transparency and communications as means to support approval procedures and the implementation of measures in all areas related to lignite mining and utilization.

Jan 1, 2011

By S. H. Miller

Biodegradable hydraulic fluids can save tens or hundreds of thousands of dollars in fines and clean up costs in the event of a hydraulic fluid leak or spill. When properly selected, applied, maintained and monitored, a biodegradable fluid will have a long useful life and will protect equipment as well as or better than conventional petroleum based hydraulic fluids.

Jan 1, 2000