Search Documents

Studies of the Main Seam in the Rapahoe Sector of Greymouth Coalfield have shown that the proportions of palynomorphs and palynomorph groups vary vertically within the seam, but remain laterally consistent. Subsequent examinations of other seams in the Rapahoe Sector have demonstrated that the changes in palynomorph proportions observed in the Main Seam are specific to that seam, effectively providing a seam 'fingerprint'. Such a characteristic signature may be used to identify the Main Seam where faulting or seam splitting confuses seam correlation between drillhole intersections. Palynomorph assemblages are derived from the original plants which formed the peat mire, and yield information on mire conditions such as climate, mineral matter input and chemistry. These depositional factors influence coal properties such as mineral content, volatile matter yields and coal breakability. Palynological data can therefore assist in development of depositional lTIodels for prediction of coal quality variations. Several other, thiner seams in the Rapahoe Sector have been demonstrated to also contain recognisable palynomorph assemblages, suggesting that other seams may also possess distinct palynomorph abundance profiles.

Jan 1, 1996

By E. J. Murphy, A. P. Rowles, John C. Holtz

"INTRODUCTION The use of sheaths or hollow cylinders of flame-extinctive materials surrounding cartridges of permissible explosives has been developed during the last few years; the history of sheathed explosives in their salient development in Belgium was treated recently in a publication of the Bureau of Mines. 6/ This development is of great interest in explosives technology, for it holds possibilities of reducing further the ignition hazards that may cause many coal-mine disasters. The township interest in sheathed explosives in this country is attested by the passage of some State laws permitting the use of such explosives on shift 7/; inquiries are received in increasing numbers concerning the effects of sheaths on practical hazards as well as the general technology underlying their use."

May 1, 1943

In line with DML Resources continual forward management policies, the Roscommon Quarry operation has recently installed and commissioned a Nordberg 7 ft Symons cone crusher and a HP 300 cone crusher. Both machines have enhanced the production capabilities and quality control of the Roscommon comminuition circuit and they will provide efficient and reliable crushing well into the next century.

Jan 1, 1994

By N. A. D. Parlee, M. M. A. El-Naggar, G. 8. Horsley

The apparatus was of a modified Sieverts type1&apos;2 with a reaction tube designed to function also as the cell component of an oxygen pressure gage. The reaction tube assembly is shown in Fig. 1 and described in Table I. The main body is a 1-in.-OD 15 mol pct calcia-stabilized zirconia tube. The ground-glass joint, g, the male part of which carried a prism for optical pyrometer use, was connected to the remainder of the Sieverts apparatus. The calibration of the cell (at its 1000°K operating temperature) for internal oxygen pressures (PO2in) in the range 0.2 to 10 9 atm was made against internal air pressures measured by mercury manometer and McLeod gage. At very low po2in values down to l<Tn atm the performance was checked by comparing pQ calculated from electromotive force measurement when the apparatus was filled with a) pure CO gas and b) a CO-CO2 mixture of the ratio CO-CO2 = 1:0.398, with Po, values calculated from the equilibrium constants of the following reactions at 1000°K:

Jan 1, 1968

By Brian Garrod

Increasing use of pressurized-face tunnel boring machines in North America has produced a similar increase in the application of precast concrete tunnel linings. Where a pressurized TBM is needed, immediate ground support and ground water pressure resistance is also required. A segmental lining installed within the TBM tail shield provides the only available means of providing such a sealed lining. This paper addresses new developments in North America in lining applications and design. For the purposes of this paper, a precast concrete tunnel lining is defined as a tunnel lining constructed using precast concrete segments that are assembled into a lining ring. The lining rings are connected adjacent to each other to form a tunnel lining. Each segment has a sealing gasket around it so that when the lining is completed, it provides a fully waterproof lining system. The ring is erected within the tail shield of the TBM and the annular gap around the ring is filled with grout as the machine moves forward. The ring is not expanded and normally provides the finished lining of the tunnel with no requirement for a second pass lining. The TBM has a series of hydraulic rams that push on the leading edge of the segmental lining to provide the sole system of forward propulsion for the machine. The rings are tapered, being longer on one side than the other. This allows the rings to be installed either on a curve or in a straight line depending on the rotational position of the rings.

Jan 1, 2008

By A. C. Fieldner

In 1927 the Carbonization Committee of the American Gas Association proposed cooperation with the Bureau of Mines in the development of suitable methods for determining the carbonizing properties of American coals. It was further proposed to apply these methods in the testing of representative coals and to make the information obtained available to the public through Government publications. A cooperative agreement was signed whereby the Gas Association contributed part of the funds necessary for beginning the project and appointed a committee to consult and advise the Bureau in the work. The Advisory Committee has been reappointed each year, and the Bureau has had the benefit of its advice. The composition and carbonizing properties of 33 coals previously tested have been given in technical papers of the Bureau of Mines and in short reports published for the most part in the Proceedings of the American Gas Association. A complete list of publications on the work previous to 1937 is appended to this report. The present report gives the composition and carbonizing properties of seven additional coals from West Virginia. The data include results of blending tests in which Beckley led low-volatile coal was used with all the high-volatile coals except the Alma coal, with which Pocahontas No. 4 coal was used.

Jan 1, 1938

By S. Acar, M. Botz

Introduction In 2007, Newmont Mining Corporation will begin construction of a milling and cyanidation leaching circuit for the Yanacocha site in Peru. Ore to be processed in the circuit contains a relatively high level of cyanide-soluble copper, and as a result, leach solutions are expected to contain elevated levels of copper and WAD cyanide. As the means of controlling copper levels in leach solution, a circuit will be installed to precipitate copper sulfide from barren solution using sodium hydrosulfide. In addition, a circuit will be installed to recover cyanide from barren solution, with recovered cyanide to be returned to the leaching circuit and treated solution to be utilized as make-up in existing heap leaching facilities. As needed to support design of the copper precipitation and cyanide recovery circuits, pilot testing was conducted in 2005 to determine preferred operating conditions and evaluate the performance of the processes. This paper presents results from the pilot testing where 99% copper reduction was achieved and 95% to 98% cyanide recovery was achieved.

Jan 1, 2007

This paper presents a resume of the likely profitable mining areas in New Zealand. It covers the main &apos;minerals&apos;&nbsp;û gold, coal, oil and gas, ironsands, silica sands, clays, lump silica, perlite, sulphur and limestone. The potential mining projects are depicted on a map of New Zealand together with the associated works involved in hydro-electric and geothermal power development requirement for industries such as aluminium, nickel ferro-silicon or silicon carbide production. The political need for mining development to relieve unemployment and reverse emigration is stressed. A case is made for exploration and development assistance by government in labour re-training, energy supply and transportation, if the tremendous losses through lack of use of human and industrial resources are to be rapidly reduced. These losses are currently estimated at $10 000 000 000 per year. The need for protection of the sanctity of contract and security of tenure of all mining operations is touched on briefly as is the need for a reasonably balanced view on conservation. However, as both of these are more properly covered in papers on the legal and environmental aspects of the mining climate, they are presented here only as they affect the economy of the mining operation. Finally, there is a brief comment on the mining climate in New Zealand relative to Australia and South Pacific mining operations.

Jan 1, 1990

By Richard E. Danell

"There are a variety of approaches for wall control blasting in open pit mining operations. Safety forworking in the pit is the principal benefit. There are also a number of economic and productivitybenefits when appropriate techniques are used. The purpose and requirements of wall control blasting can vary quite significantly for different operations. When considering blast design, geology, geotechnical factors, drilling, explosives, economics and blasting history are all part of the engineering design process. In many operations, there is a high reliance on blasting history and economics for determining wall control blasting measures. This presentation outlines approaches that broaden the design process and discusses their advantages."

Jan 1, 1997

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 M. J. Beus, B. Stewart, S. Iverson

Synopsis U.S. Mine Safety and Health Administration (MSHA) accidents statistics have identified ore-pass hazards as a significant safety problem in U.S. underground metal mines. The statistics show that nearly 75% of injuries are directly or indirectly related to pulling or freeing of ore-pass chutes, the use of hand tools in ore passes, fails of broken rock in ore passes and structural failures of chutes or gates and ore-pass walls. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating hazards in and around ore passes in hard rock mines. Risk assessment methods, such as fault-tree analysis, have been employed to identify the most probable causes of orepass failures, define research priorities and analyse the factors that result in malfunctioning and unsafe ore passes. Static and dynamic loads are being measured in a laboratory setting with the use of a reduced-scale orepass mock-up. Field tests are being initiated in mine ore passes to determine static and dynamic loads. Data from the test ore passes are being compared with data from the mine to characterize true system behaviour. Computer modelling with the use of closed-form solutions, finite-element analyses and a newly developed particle flow code predicts static and dynamic leads from the flow and the impact of ore and waste in the ore pass. Preliminary results indicate that dynamic impacts from ore and waste rock might be considerably greater than expected. The total static load is substantially less than is typically used fur the structural design of chute and gate support members. It is suggested that damping factors, normal and shear stiffness and mass frictional characteristics have a significant effect on particle flow and resulting impact loads. This is being verified with the use of results from laboratory tests, field tests and particle flow analyses. Ore passes are vertical or steeply inclined openings in a rock mass through which ore and waste are transported and where they mar also be stored. A typical underground mining system is shown in Fig. 1. The arrows indicate the locations of ore passes and loading pockets and their relative configurations. The control of material flow is potentially one of the most hazardous operations in underground mining. According to MSHA data. most of the ore pass-related accidents in the U.S.A. are associated with the loading-unloading cycle and removal of blockages from ore passes. In particular, attempts to free ore hang-ups have resulted in multiple fatalities. The hazards are obvious; there is uncertainty as to when the ore will break loose and miners are unable to escape falling rock to a safe location. Although ore passes and chutes and gate systems for underground metal and non-metal mines roust meet the requirements specified in the U.S. Code of Federal Regulations (CFR). Parts 57 and 75, recent structural failures of ore-pass linings and gates have underlined the lack of adequate ore-pass design standards available to both MSHA enforcement staff and mine engineers. Because of the importance of an ore pass to the safe operation of a mine design criteria need to be assessed and new guidelines developed. Researchers at the Spokane Research Laboratory of the Nationals Institute for Occupational Safety and Health (NIOSH) are investigating hazards in and around ore passes in hard rock mines and studying design criteria for ore passes. The near-term goal is to conduct laboratory and field experiments and computer modelling to evaluate the ore-pass design criteria currently used. Literature searches, field site

By Michael D. McGill

The effect of fragmentation size distribution as it relates to front end loader productivity was evaluated by comparing loader cycle times to fragmentation size of the shot rock. At Gold Mine in Southern Utah, a gold deposit containing both limestone and sandstone formations were blasted in the same shot.

Jan 1, 1994

A general outline of the significant features in the quality and manufacture of the more common refractories is given. Where possible, linkage between quality development and control and service applicationhas been shown and explained. INTRODUCTIONThe refractory industry is no stranger to change. New processes and revision of old processes in other industries are the harbinger of new and revised products in refractories.Few of the changes are dramatic; generally they are evolutionary rather than revolutionary. New developments are additional to, and inclusive of, established practice.Therefore in this paper it is necessary to repeat much of what is already known in order to show the development taking place.FIRECLAY REFRACTORIESGeneral technology Fireclay refractories are the most common, the most varied and the most versatile of all refractories. Virtually any composition of silica and alumina up to the composition of kaolin is possible. For purposes of comparison they may be classified in the Continental fashion in accordance with chemical composition or in the American way according to &quot;duty&quot;. That the two methods are equivalent is shown by an inspection of the alumina-silica diagram of Bbwen and Greig (1924). &apos;Fireclay refractories are composed of a glassy and a crystalline component derived from the chemical and physical nature of the raw materials used in their manufacture.

Jan 1, 1961

By Greaves M. C

X-ray fluorescence spectroscopy used for the analysis of mill samples results in improved control of flotation concentrators.Techniques and equipment for sampling pulp streams, filtration and drying, grinding, briquetting and X-ray fluorescence analysis of samples have been developed.The current methods in use permit the analysis for lead and zinc in six pulp samples within 30 min total elapsed from the start of sampling. The X-ray method gives a precision at least equal to the former routine wet-way assay methods.The equipment is used also for pilot plant control, as a means of solving complicated analytical problems and in the rapid qualitative analysis of exploration samples.INTRODUCTIONIn milling and concentrating operations, classical methods for the assay of lead and zinc have been mainly of use for accounting purposes and for the post-mortem examination of plant operations, but have been of little value for rapid mill control. Where attempts have been made to apply these methods to control assaying, it has been necessary to modify the procedures and introduce short cuts which have tended to reduce their reliability.Even with these shortened procedures, the time taken to obtain a limited amount of information rendered them of little value for the control of milling operations where sudden, large fluctuations can occur. In recent years, a number of new and rapid analytical techniques, based on physical rather than chemical principles, have been introduced.These include direct reading emission spectroscopy, x-ray fluorescence spectroscopy and atomic absorptionspectroscopy.

Jan 1, 1964

By E. L. Garton

[Analyses of may crude oils produced in Louisiana are included in reports that t have boon published by the Bureau of Mines. The first report, giving, analyse of 6 Louisiana crude oils, was 3 published in 1921 and this was followed a year later by Report of Investigations 2416,4/ giving 7 additional analyses. The eleven most important of these analyses were incorporated in Bulletin 291.5/ issued in 1928 In 1934 analyses of 26 crude oils produced in southern Louisiana were published.6/ The percent report presents analyses of 72 additional samples of crude oil from 45 fields in 23 parishes In Louisiana.]

Jan 1, 1939

By Seth T. Reese

REPORTS received from operating companies by the Bureau of Mines, United States Department of the Interior, indicated marked progress in the reduction of injuries to employees in the coking industry in 1951 as compared with 1950. The fatality rate (0.14) per million man-hours of exposure declined 33 percent and was the second best performance since statistics on the industry were first collected in 1916. The nonfatal-injury rate (10.94), the best since 1940, declined 8 percent and was bettered only in 8 of the past 36 years. The nonfatal rate is based on all injuries resulting in loss of time for more than the remainder of the day on which the injury occurred. The exposure to hazard, as represented by the number of man-hours of work time during the year, was 7 percent higher than in 1950 and, except for the year 1943, was the highest since 1920. The fatality rate for men employed at beehive-coke ovens decreased 16 percent and the nonfatal-injury rate 23 percent, while the man-hours of work time or exposure increased slightly over 16 percent. The fatality and nonfatal-injury rates at byproduct ovens declined 33 and 2 ½ percent, respectively, while the number of man-hours worked increased 6 percent.

Jan 1, 1954

The Broken Hill orebody ,occurs in the Willyama Complex, a block of Precambrian rocks which have been strongly folded and metamorphosed at moderate to high grade. Although -the origin of the silver-lead-zinc mineralization remains obscure, recent investigations have substantiated the view that the orebody has undergone concomitant high grade metamorphism with the enclosing wallrocks. The mesoscopic structures produced by this metamorphism are described, and the possible processes Telating to their formation are disoussed.In the high grade ore, metamorphic structures which can be recognized are foliation and lineation, wallrock fragments, layering, flow folds, ore breccias, and sulphide bearing veins. These structures can be related to processes involving plastic flow and fluid phase transport of the mineral assemblage. &apos;In areas of low grade mineralization adjacent to high grade ore, the structures more closely resemble those produced in -the wallrocks-foliatlon, lineation, layering, folds, and sulphide injections. Within areas of high grade ore, lenses and pods of manganese silicates Probably represent original inhomogeneities in the ore, i.e., portions of manganese-rich and sulphide deficient rock which have been metamorphosed to manganese silicates.From the structures displayed, a sequence of events has been established for the plastic flow of ore during deformation.

Jan 1, 1975

By Michael J. Lehnen

Slurry diaphragm walls are commonly used as both temporary excavation support walls, and permanent structural walls, for circular shafts and long rectangular structures (such as underground subway stations); however, they are not commonly used for more compact rectangular or square shafts. In these instances, a second wall is typically cast inside the slurry walls to form the permanent structure. This paper discusses the approach used on the Silicon Valley Rapid Transit Project in California to analyze these compact rectangular types of structures for static and seismic loading, and to determine whether or not slurry walls can be confidently used as both the temporary and permanent walls for two tunnel ventilation shafts.

By Baxter J. L

Post-tertiary training programmes have been designed and produced for geologists at different levels of understanding and expertise in the relationship between gold mineralization and shear zones. A workshop format was used as it allowed both clients and facilitators to participate in the learning process. Evaluation by facilitators and participants refined the workshop programme as an effective skills oriented learning process. The general observation is that post-tertiary training in small, interactive, practical, learning oriented groups is far better than lecture oriented short courses for developing skills based learning. The evaluation indicates that the process in post-tertiary training must include aspects which are both useful and used.

Jan 1, 1989

By Floyd Varley

In deep and highly-stressed coal mining, advanced design practices are used to minimize the potential for damaging events to occur. Despite these design efforts, the hazard of coal mine bumps can not be completely eliminated. This paper will review current and historic work practices used internationally to minimize the hazard to miners from mining in conditions which could produce a bump. These site specific work practices have a common base in monitoring for conditions which could result in a bump and application of controls to prevent the occurrence or minimize the severity of an event where miners are working. Monitoring practices range from purely observational to semi quantitative. Control methods attempt to initiate events in a controlled manner, absorb the energy of a potential event or reduce the potential for or magnitude of an event by altering the stress conditions of the mine workings. Building from the experiences of other coal fields, an empirical framework to manage the potential hazard of coal mine bumps can be developed to enhance the level of safety provided by prudent mine design.

Jan 1, 2008