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By S. K. R. Iyengar

This report presents the results of a study to develop optimal designs for light-weight mine roof supports for use in underground coal mines. A load capacity of 196 kN (22 tons) and a height adjustable between 1.829 m (72 inches) and 2.438 m (96 inches) were taken as the design parameters and the design goal was a unit weighing less than 22.3 kg (50 lbs). Three alternative design concepts were explored, viz. mechanical, hydraulic, and hydro-mechanical and a total of 13 designs analyzed in detail. Steel, aluminum alloy and composites were the main potential construction materials investigated for suitability from structural, life, and safety and other considerations. The designs considered most promising for development were: (i) the mechanical screw-pin type using telescopic tubes and a fine adjustment screw thread section (ii) the all-hydraulic type, of steel, aluminum alloy or aramid graphite construction (iii) the hydro-mechanical design using telescopic tubes and a short stroke hydraulic cylinder for fine adjustment It is shown that by using realistic mathematical models for stress and deflection calculations, it is possible to reduce prop weight to the design goal. The analysis presented for all-hydraulic props is applicable to hydraulic cylinders on all mining equipment and similar machinery. This report includes the computer program and user's guide for analyzing hydraulic cylinders as well as a cross-indexed bibliography on structural composites.

Jan 1, 1978

By Georgene Renner, William R. Yernberg, Steve Kral

Agapito Associates (AAI) provides consulting services in geo-engineering, mining engineering and related disciplines. Founded in 1978, the firm operates out of offices in Grand Junction, CO, Golden, CO and Lombard, IL. Members of the staff include mining, civil and geological engineers, physicists, geologists, numerical analysts, computer specialists, instrumentation specialists, plus administration and technical support personnel. AAI has provided consulting and engineering services to mining companies producing base metals, precious metals, coal, potash, trona, limestone, oil shale and salt, and to defense and nuclear-waste disposal industries. AAI also provides services for measuring in situ horizontal stresses using an advanced biaxial overcore stress downhole measurement system developed by Sigra of Australia. Since 1978, AAI has measured in situ stress in copper, oil shale, molybdenum, trona, limestone and coal mines, and in tunnels and concrete structures. Since 1994, the staff has completed 527 overcore stress determinations. AAI has the equipment and personnel for overcoring, sample coring and instrumentation installation in limited access, surface and underground mines. Portable Longyear CP-65 drills, borehole deformation gauges and strain indicators are used for difficult-access overcoring and are permissible for use in gassy mines.

Jan 1, 2006

By A Webster, T Murphy

Block cave mining, in its broadest sense, has transitioned from an orebody/rock mass determined method of extraction, to a low-cost and high production mining method that may be applied to any large ore deposit. This inherently means that caving is now required in more complex rock mass conditions where assistive damage, through preconditioning, may be necessary. This requires comprehensive understanding of the geology, and its interwoven relationship with geotechnical parameters, and is made more challenging due to limited exposure in block cave mines. Limited mine development throughout the cave volume equates to a heavy reliance on drilling data in terms of observations, modelling of the mine geology, and collection of geotechnical data. This translates as increased uncertainty of geological and geotechnical models and has potential to impact significantly on the ability to make informed decisions in the design and operation of the cave mine.Modelling of cave propagation behaviour requires a complex, coupled system of draw of material, flow of material through the cave stocks, and propagation of the cave-back assisted by autogenic stress-related breakage of the rock mass, manifested as seismicity. The role of geological features in the process of cave propagation is not well understood and requires evaluation on a mine-specific basis, given the diversity of geological controls/settings of ore deposits and local variability of stress fields.Seismic monitoring systems can elucidate key geological features and domains, as heterogeneous seismogenic activity is observed ahead of the advancing cave-back. The observations made from analysis of seismic monitoring data may have potential to be used as a validation tool for numerical modelling of predicted cave behaviour in similar geological settings (eg next lift/panel).Understanding of the geological structure, at all scales, is critical to optimise the design and operating decisions made in a block cave operation. At present, intermediate-scale structure, anisotropy, mineralogy and model uncertainty may be neglected or under-represented despite their likely significant role in the mechanisms of cave propagation.Insights from an analysis of the Ridgeway Deeps block cave mine are discussed in this paper.CITATION:Murphy, T, Webster, A and Chitombo, G, 2016. Beyond rock mass characterisation – the impact of geology on block cave mining, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 861–872 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By K. J. Oliver, A. G. Meyers, S. P. Hunt

Deformation Rate Analysis (DRA) and porosimetry have been used to demonstrate the “stress memory” effect in rock and to estimate the vertical in-situ stress in samples of fine-coarse grained sandstone and carbonaceous mudstone. The results of this study indicate that the stresses predicted using both methods are similar to those determined from depth and density of the overburden rocks. The results confirmed that DRA was still applicable even when the core had been sampled 18 months prior to testing. Additionally, the DRA results were modelled using the software PFC2D. A uniaxial test was modelled using the same rock parameters as those observed for the actual core samples. This numerical technique can be used as an aid for DRA results analysis, and can also be used to predict the minimum stress level at which the DRA technique is applicable. The results confirm that any rock mechanics laboratory having standard test equipment could apply the DRA method combined with standard UCS testwork to determine the in-situ stress. Mit der Analyse der Deformationsrate (DRA) und der Anwendung der Porosimetrie wird der Spannungsgedaechtnisseffekts (Stress Memory Effect) im Fels demonstriert, und es werden Abschaetzungen fuer die vertikale in-situ Spannung einer Probe aus mittelgrobem Sandstein und carbonierten Lehmstein getroffen. Die Ergebnisse dieser Untersuchung zeigen, dass die mit Hilfe dieser beiden Methoden ermittelten Spannungen sind vergleichbar. Die Ergebnisse bestaetigen, dass DRA noch anwendbar ist, wenn die Proben schon 18 Monate vor Untersuchungsbeginn gesammelt worden sind. Darueber hinaus wurden die DRA Ergebnisse mit Hilfe des Sofwarepakets PFC modelliert. Ein einaxialer Test wurde mit genau die gleichen Felsparametern, die fuer die eigentliche Probe gelten, modelliert. Diese numerische Methode kann sowohl als eine Unterstuetzung fuer DRA Ergebnisanalyse als auch zur Ermittlung der minimalen Spannung, bei dem die DRA Methode noch anwendbar ist, herangezogen werden. Die Ergebnisse bestaetigen, dass jedes Felsmechaniklabor, das mit den ueblichen Testgeraeten ausgestattet ist, die DRA Methode in Kombination mit dem Standard UCS Testarbeit zur Bestimmung der in-situ Spannungen anwenden kann. L'Analyse du Taux de la difformité (DRA) et les porosimetry ont été utilisés démontrer le " effet de la mémoire " du stress dans roc et estimer le stress dans - situ vertical dans échantillons de grès du grained fin grossier et mudstone carbonifère. Les résultats de cette étude indiquent que les insistances ont prédit utiliser les deux methods est semblable à ceux déterminés de profondeur et densité du surchargez des rocs. Les résultats ont confirmé ce DRA était encore même applicable quand le coeur avait été goûté 18 mois avant tester. En outre, les résultats DRA étaient des modelled qui utilisent le logiciel PFC2D. Une épreuve de l'uniaxial était modelled qui utilise les mêmes paramètres du roc comme ceux observé pour les réels échantillons du coeur. Cette technique numérique peut être utilisée comme une aide pour DRA résulte analyse, et peut aussi être utilisé pour prédire le niveau du stress minimum à que la technique DRA est applicable. Les résultats confirment que tout laboratoire des mécaniques du roc qui a le matériel de l'épreuve standard pourrait appliquer la méthode DRA combinée avec testwork UCS standard pour déterminer le stress dans - situ.

Jan 1, 2003

By V. Balakrishnan, A. Hewitson

"The Kudremukh Iron Ore Company Limited, a government of India enterprise, has constructed iron ore mining, crushing, handling and concentrator facilities at Kudremukh, in southwest India. Concentrate produced is pumped 65 km to dewatering, storage and ship-loading facilities which were built at the same time at the sea port of Mangalore.A computer-based distributed process control system was implemented for all operations at Kudremukh and to interface with and monitor the Mangalore plant.The control system is examined from various standpoints, beginning with a description of its architecture, method of process input/output connection, and major hardware items.Software considerations and process applications are then looked at, with a review of the integration of the computer vendor's system software with user-developed applications programming. A control example of crusher operations is provided.Following the descriptive segment is a discussion of the design considerations and decision factors involved in the implementation of such a system considering the type of process and the remote nature of the installation site. It ends with a review of actual operating experience and conclusions regarding both this system and future similar applications.ScopeThe following is a discussion of the computer-based process control system applied for the Kudremukh Iron are Company Limited's ore handling, concentrating and shipping facilities located in South India.A general description of the process and plant equipment will be followed by an examination of the control system from the points of view of hardware and signal flow, software requirements, design considerations, implementation logistics and operating experience. Conclusions will be drawn concerning this and future computer applications."

Jan 1, 1984

By Richard H. Bares

One criterion central to most definitions of reclamation is the restoration of mined lands to their original productive potential. This is often difficult to achieve on mined lands in the Northern Great Plains because of the rigorous climate (Bares 19;2) and various soil related problems including sodicity, salinity, soil permeability, low organic matter and plant nutrient deficiencies (Malakondaiah and Safaya 1982). Field study sites were established on recontotured mined areas during the early 1970's (prior to the topsoil mandate) in which several amendments were tested for their ability to improve spoil/topsoil conditions and, hence, increase plant production. Physical and chemical properties of these control (untreated) and amended spoils and topsoils have been summarized (Safaya et al. 1982). A number of grass and legume species combinations were studied. The general effects of one time (prior to seeding), single rate (approximately 100 mT ha-1) application of leonardite and/or slack coal to spoils and topsoils was the reduction of grass dry matter yields (NB 1 test site: dry matter yield (DMY) without slack was 110 g m 2 yr I ; DMY with slack was 80 g m -2 yr 1 I and the promotion of legume establishment and yield (SB test site: DMY without leonardite was 13 g m 2 yr -1; DMY with leonardite was 93 g m 2 yr 1). On South Beulah topsoil, treated with leonardite, production of weedy species was remarkably lower than that without leonardite (SB test site: DMY without leonardite was 252 g m - yr -1; DMY with leonardite was 177 g m 2 yr 1). The general effect of commercial fertilizer applied one time prior to seeding (rates ranging from 9-13-0 to 44-1 12-28 kg ha-1 of N-P-K) was to increase plant production during the first two to three years after which the effect disappeared. This effect was much more pronounced on spoils (NB I test site: DMY on spoils without fertilizer was 53 g m -2 yr -1; DMY on spoils with fertiliser was 132 gm -2 yr -1). Weedy species accounted for most of the biomas, production during the first growing season. Three of the test sites were designed to study plant production on topsoils and spoils. Establishment and production of grass species were comparatively better on topsoils (30 cm in depth) than on spoils while legumes were most successful on the soils (Center test site, 1979; DMY of grasses on topsoil was 170 g m 2 yr -1 DMY of grasses on spoils was 52 g m -2 yr -1; DMY of legumes on topsoil was 20 g m -2 yr -1; DMY of legumes on spoil was 191 g m 2 yr -1). Total plant production on topsoiled (302 m thickness) plots at the South Beulah site (DMY in 1979 of 269 g m 2 yr 1) was comparable to that of native western wheatgrass prairie (DMY of 262 g m -2 yr -1). An experiment was conducted to find out if time of planting would have any effect on establishment of grasses on spoils. It was fund that late fall seeding was superior to spring planting for establishment of wheatgrasses at NB 3 test site (Control Plot, 1975: DMY on spring-seeded was 1 g m -2 yr - 1; DMY on fall-seeded was 55 g m -2 yr -1). In general, wheatgrasses (slender, streambank, thickspike and western) yielded the most aboveground biomass of all the grass species tested; yellow sweetclover was the most successful legume. Yellow sweetclover established and was productive on both spoils and topsoils but only where competition with grasses was apparently minimal. Durar hard fescue established and thrived on topsoil but dry matter production was low compared to that of wheatgrasses. Emerald crown-vetch demonstrated a potential for growth on spoils where water conditions were adequate, whereas side-oats grama, prairie sand-reed, alkali sacaton, and bird's -foot trefoil demonstrated only sporadic success. Little bluestem did not become established at any of the test sites. Peak production of the planted species, especially grasses, was generally reached by the second week of July. Legume and weed production continued to increase into late August.

Jan 1, 1982

By F. W. Wood

The Bureau of Mines has sought clarification of the Ti-TiN system by studying the phases formed by diffusion reactions between titanium and titanium nitride. Reaction couples were prepared by embedding pockets of TiN powder in arc-melted buttons of titanium. Specimens were vacuum annealed at nominal temperatures of 800°, 950°, 1,200°, and 1,500° C. Metallographically mounted cross sections from reacted specimens and from some that were not annealed were examined optically, with an electron microprobe, with an election microscope, and by X-ray diffraction. Each annealed specimen contained a segregated core primarily of d-phase material, an ?-phase diffusion layer, an a-phase diffusion layer, and host metal. On the basis of corresponding microprobe analyses, and considering results of certain other research, a new phase diagram is proposed. It contains no qualitative innovations, only quantitative adjustments. Results were also analyzed from the viewpoint of diffusion behavior. Diffusion coefficients calculated for the ? phase were sufficiently scattered that the parameters are very tentative. Nevertheless, the diffusion behavior reported is in reasonable agreement with one of two prior studies if it is assumed that the earlier investigators were mistaken in their identification of the nitride phase in which the diffusion occurred.

Jan 1, 1974

By R. H. Atkinson, R. N. Rhoda

An improved technique has been developed for the deoxidation of palladium with aluminum which is especially suitable for use in making small castings with an induction-melting and casting machine. The effect of various crucible linings on the efficiency of the residual deoxidizer and accompanying oxide film in protecting palladium against oxidation during remelting also has been examined; the preferred crucible lining consists of zirconia cement. THE objective of this work was to develop a simple method of deoxidizing induction-melted palladium which would be suitable for use by manufacturers of jewelry and other small castings. In a common method of deoxidizing torch-melted palladium a piece of aluminum foil is dropped on the surface of the molten metal. If a film is present, which is usually the case, it must first be removed by oxidizing the molten metal thoroughly because it would interfere with the entry of the aluminum into the melt. Removal of the film is probably facilitated by a mild fluxing action of the silica crucibles which are used for torch-melting. However, removal of an alumina film from molten palladium in the crucibles normally used for induction melting is a much slower process and it became necessary to modify the de-oxidation procedure. In the modified procedure the charge is simply melted and the desired amount of aluminum, crimped to one end of a tungsten wire, is plunged through the film into the palladium and the wire immediately withdrawn. The trace of tungsten which dissolves along with the aluminum can be avoided, if considered objectionable, by using a palladium wire. In view of the persistence of the alumina film under the conditions of induction-melting it also was decided to ascertain the efficiency of this film in protecting palladium against oxidation during repeated remelting and casting. Melting Equipment and Materials The equipment used for melting and casting consisted of an Ecco GC:6, 6 to 8-kva high-frequency converter and an Ecco M34B centrifugal casting machine. This unit is being increasingly used for making jewelry and dental castings and it also has been found useful in making exploratory melts of a variety of nickel alloys, for which purpose it is well suited on account of its speed of melting and economy of material. A description of the machine and its operation will be published elsewhere.' A common palladium jewelry alloy, 95.5 palladi-um-4.5 ruthenium (referred to as "palladium" in the trade), was selected for the deoxidation tests. It was available as melting stock which had been melted in air to free it from oxidizable impurities, and also as clean scrap from previous melts which had been deoxidized with aluminum. The latter was thought to be typical of clean "palladium" scrap to be found in a manufacturing jeweler's establishment and it is also similar to one brand of "casting palladium." By the same token, the oxidized melting stock corresponds to "casting palladium" after the latter has been melted and thoroughly oxidized: Pure aluminum wire (99.9 pet), 0.032 in. diam; 1 in. = 0.036 g. Scrap tungsten wire, 0.014 to 0.020 in. diam. Argon, commercial water-pumped; 99.9 pet pure Experimental Procedure Samples of about 50 to 75 g of the palladium alloy were melted in a crucible lined with a proprietary refractory alumina cement. Some charges were melted in air, others in argon. The oxidized melting stock was melted and solidified a number of times in order to remove as much oxygen as possible before deoxidizing, but this treatment was unnecessary in the case of scrap. In either case the metal was deoxidized with aluminum (0.01 to 0.05 pet) by the

Jan 1, 1959

By experience we know about the natural event of ocean-tides. In geophysics we say that the earth-tides phenomenon is the elastico-viscous response of the earth's body to the attraction potential of moon and sun. By the fact that the tides on the planet take place in a regular periodic frequency, due to the earth rotation of 24 houres for one cycle, the rotation of the moon in about 28 days around the earth and finally to the rotation of the earth-moon combination around the sun in 365 days this phenomenon is a very important one in geophysics. The exact calculation of the acting forces is possible and the comparison of the earth's body response to these forces as well.

Jan 1, 1987

By S. S. Makgato

In this study, coke oven tar additions over a range of 0?8 wt.% were evaluated as a possible substitute for imported coal fractions. The coke oven tar used was collected from tar decanters in the byproducts section of the coking plant. The moisture content in the tar varied depending on the residence time and water carryover from the coke oven tar separators to the storage tanks. Moisture contents of 1 wt.%, 3 wt.%, and 6 wt.% were investigated in order to evaluate the effect on coal blend, carbonization, and coke properties. At 6 wt.% moisture content with 6 wt.% coke oven tar, although the coke quality improved the yield showed a 4% decrease. On the other hand, 1 wt.% moisture content with coke oven tar of 6 wt.%, increased the yield by 1% and the coke quality improved. However, the latter process was characterized by an excessive increase in wall pressure and pushing energy, both of which are detrimental to the oven walls. The optimum moisture content in coke oven tar was found to be 3 wt.% with a coke oven tar addition of 6 wt.% in the coal blend. With these conditions, the coke properties improved and wall pressure and pushing energy were acceptable. However, a decrease in coke yield of up to 2% was observed. Despite this, coke oven tar addition is considered to be a viable option based upon economic factors of a reduction in the quantity and cost of imported coking coals that is required to achieve the same optimum final coke product. Keywords coal substitution, coke oven tar, tar moisture, coal blend, coke, coke quality.

Nov 1, 2013

By S Jephcott

The McArthur lead-zinc-silver deposit is of the stratiform type. It consists of a mineralised bituminous shale sequence containing some tuffites, numerous graded beds and isolated slump breccia horizons. The principal sulfides; pyrite, sphalerite and galena, are essentially restricted to the shales and the genetically unrelated turbidites contain only minor mineralisation. The geochemistry of the deposit has been investigated with respect to the stratigraphic column and mineralogy of the sediments. A sedimentary origin is advocated for the deposit. Volcanism, thermal spring activity and high salinities, perhaps related to the Emu Fault, are considered as contributing factors to ore genesis. The metallurgy of this deposit is discussed in relation to its geologic history.

Jan 1, 1971

By Associates

The headwaters of Skippers Creek and the Shotover River are reputed to be among the richest alluvial gold catchments in the world. This alluvial gold has no doubt been derived from reef systems similar to, and associated with, the Bullendale lodes. Physiographically the prospect covers steep ridges and deeply incised gullies between the Richardson Mountains in the west and the Harris Mountains in the east. Vegetation is mainly tussock with bush either side of Murdochs Creek. Access to the area is by metalled road to Skippers and then by 4WD track to Bullendale. Alternatively the prospect area can be reached by helicopter from Queenstown in around ten minutes.

Jan 1, 1992

By F. T. Cawood

Inauguration of the new political dispensation in South Africa in1994 initiated a dynamic shift in the ownership, management and development of the country?s affluent mineral heritage. The process of substituting the old South African regime with a new equitable system started soon after the 1994 election of the African National Congress (ANC) to parliament. The Congress?s Freedom Charter revealed the intent of the new dispensation when it called for radical transformation of mineral development. However, since then there have been important changes affecting the rules of mineral development. These are: ?A drastic change in politics ushered in by negotiation, a spirit of reconciliation and a desire to settle disputes peacefully ?The globalization of the South African mining industry in tandem with the opening of domestic mineral resources to foreign capitalists and ?The introduction of sustainable development as a holistic approach to mineral development in order to replace traditional narrow-minded environmental management. Each of these significantly shaped the new mineral investment environment of South Africa. This paper represents a summary of the historical developments leading to the current Mineral and Petroleum Resources Development Act No. 28 of 2002, its regulations, the much publicised Broad-Based Socio-Economic Empowerment Charter, its associated Scorecard, and the Draft Royalty Bill.

Jan 1, 2004

By Kay E. Goldberg

The Bureau of Mines conducted a study to develop and evaluate a training workshop for mine safety training personnel. The workshop was based on the Instructional Development Institute (IDI) which has been used for nearly ten years to train educators and administrators in the application of a nine-step model for defining, developing, and evaluating instruction. The Mining Instructional Development Institute (MIDI) was developed by investigators at the University of Southern California as a two-phase project. Phase I involved the modification of the six-day IDI program (including audiovisual presentations, workbooks, games, and exercises) for use by mine safety trainers as a workshop lasting three and one-half days. Phase II involved the evaluation and validation of the prototype MIDI workshop by means of a two-stage jury of experts and a prototype field trial. On the basis of data collected in the validation process it was determined that the institute provided an effective and useful method of instruction in mine safety training and that the institute would be especially valuable for mine safety training administrators and supervisors.

Jan 1, 1980

By T. Z. Mugodi, D. R. Fleming

Information and Communications Technology (ICT) is defined as ‘The goods and services that support the electronic display, processing, storage and transmission of information’. Early in 2002 the South African Department of Trade and Industry (DTI) commissioned a study into the diffusion and adoption of ICT in eight sectors of the economy. The platinum mining Sector was one of these. The key findings presented in this paper are based on the platinum sector component of that study. The paper examines the theoretical basis behind technology transfer and innovation diffusion and presents the results of an ICT diffusion survey carried out in the South African platinum mining sector. ICT is shown as the modern day technological tool which is an accelerator of economic development. The current state of ICT diffusion in the platinum mining sector is defined and projections for the near future are given. Recommendations which will ensure smooth and full adoption are presented and justified.

Jan 1, 2003

By M. Ayhan

Drums of a modern longwall shearer are manufactured to include various constructional features conveying extracted material onto the face conveyor as efficiently as possible. Designing a drum with a conical shell or with reduced vane length, consequently with a stepper vane angle, is the most widely employed method in an attempt to increase loading efficiency. This study compares loading performances of two such drums, one having a conical shell with modified loading vanes, the other with a cylindrical shell with reduced vane length. Firstly, the loading performances of drums are predicted and the maximum haulage rate attainable with the drums are calculated. Then the performances of drum are compared by long-term comprehensive underground trials with coal shearers under similar conditions during the production operation of Park Termik Cayirhan coalmine in Turkey. Although higher loading performance is predicted for cylindrical drums, the in situ trials point out that Globoid drums have a slightly higher loading performance than cylindrical drums. Furthermore, the relationship between operational variables, i.e. extraction height, sumping depth, haulage rate and in situ loading performance, were investigated statistically on the basis of data gathered during the underground trials. Keywords: longwall mining, shearer drums, loading performance.

Jan 1, 2006

THE solid nonmetallic inclusions that are present to some extent in all commercial steels have been variously designated. In early references they were usually called slag inclusions, and. this terminology is still retained to some extent. On the premise that all nonmetallic matter produced in a metallurgical process is slag, this can be justified. We have come to think of slag, however, in a more restricted sense, and calling these particles slag inclusions is further objectionable because it fosters the erroneous concept that they are actually incorporated portions of furnace slag. Rarely is this true. The term sonims (coined from solid nonmetallic impurities) was proposed many years ago but never came into common use. In general the term "nonmetallic inclusions" seems to be satisfactory and adequate. NATURE AND CONSTITUTION OF NONMETALLIC INCLUSIONS From the standpoint of origin, inclusions fall naturally into two classes: (1) those that occur as a result of reactions taking place in the body of the molten or solidifying metal and (2) those that result from the mechanical incorporation of refractories or other materials with which the steel comes in contact. The former are by far the more numerous and have been called indigenous, natural, or native inclusions. The latter are by their very nature sporadic in occurrence and have been called exogenous, accidental, adventitious, or foreign inclusions. They are often referred to as the "slag stringer" type, though here also the material is not likely to be furnace slag. Substances Found in Inclusions. Nonmetallic inclusions are composed principally of oxides and sulphidea but carbides and nitrides sometimes play an important role. In the case of indigenous inclusions the reactions by which these particles are precipitated from the molten or solidifying steel may be caused by (1) oxidation such as may occur during refining or during tapping and teeming, (2) deoxidation by added alloys, (3) change in equilibrium constants as the steel cools to the freezing temperature, (4) decreased solubility with lower

Jan 1, 1944

By Jeffrey Johnson, Carl Sunderman, Ted Williams, Stephen Signer, Douglas Bayer

To measure the loading behavior of friction bolts, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) installed strain gauges on the interior of friction bolts and developed a battery-powered miniature data acquisition system (MIDAS) that fits inside the hollow portion of the friction bolt. The advantages of this system are that it is protected from face blasts and eliminates the need for external wiring. Laboratory pull-out tests showed that friction bolts installed in a concrete block with resin were loaded to about 1.8 tons/ft of bolt length; bolts installed without resin were loaded to 1.3 tons/ft. Three strain-gauged friction bolts were installed at Hecla Mining Company’s Gold Hunter Mine, Mullan, ID, in the wall or rib of a mechanized cut-and-fill stope. The object of these tests was to establish an installation procedure for the bolt-and-MIDAS combination and to evaluate performance. The stope was advanced in three 15-ft increments and strains induced in the rock bolts by stress changes in the rock were recorded every 30 minutes. The MIDAS proved to be rugged enough to withstand the shock and vibration from nearby (5 ft) face blasting. Data from MIDAS showed that the friction bolt installed with resin was the most sensitive to each face advance. It showed a steady increase in loading to a maximum value of 1000 microstrain. The friction bolt installed without resin showed stick-slip behavior with loads to a maximum of 400 microstrain before the stope was completed.

The theme of this Conference is 'The Future of Mining in New Zealand' to be addressed at a time of deepening economic concern. To ensure the assessment and development of our mineral resources in a competitive, safe and environmentally acceptable way a modest supply of a rare commodity û the professional mining engineer û must be assured. This paper briefly' reviews the history of mining education in New Zealand, discusses relevant overseas academic concerns and actions and discusses recent local trends which have led to a most serious recruitment position in the Department of Mining Engineering at the University of Auckland. Conclusions are drawn and proposals made which may remedy this situation which could have serious economic and sociological consequences for New Zealand.

Jan 1, 1991

By A. K. Anyimadu

Ongoing development work on ultra-fine grinding for various applications at the Group?s concentrators has been conducted by Anglo Platinum over the last few years. Current potential applications for mainstream grinding and concentrate grinding are the subject of a group-wide research and development programme. The first 10 000-litre 2.6 MW IsaMill was jointly developed by Anglo Platinum, Xstrata Technology and Netszch for installation at the Western Limb Tailings Re-treatment project in Rustenburg, South Africa. The unit was commissioned in late 2003/early 2004,and has operated in an intermediate concentrate regrind application successfully since. This paper describes the operational performance to date, as compared with the original duty specifications and objectives. The first mainstream M10 000 IsaMill with a 3 MW drive will be operational in November 2006 at the Potgietersrus Platinum (PPL) ?Platreef? Sandsloot Concentrator in South Africa?s Limpopo Province. Keywords: Western Limb Tailings Re-treatment Plant, IsaMilling, Platreef, platinum, palladium, PGMs, tailings.

Jan 1, 2007