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By P. Oyanader

"In 2001, the Catholic University of Chile undertook a maintenance benchmarking study of six open pit copper mines having mill capacities varying between 18,000 t/d and 156,000 t/d, and collectively responsible for 58% of Chilean copper production. This paper describes the methodology used to conduct the study, as well as the overall results. Key performance indices were selected to measure the effectiveness, efficiency, and development of the maintenance process. Using a balanced scorecard philosophy, these indicators were divided into client satisfaction, financial, internal process, and learning and growth indices.Maintenance was found, on average, to be responsible for 44% of mine production costs. Percentage planned maintenance of equipment fleets was found to be low by world standards, averaging 35%, 56%, and 44%, respectively, for blasthole drill, shovel, and haul truck fleets. Fleet availabilities were found to be significantly influenced by the percentage of planned maintenance achieved, while maintenance cost per equipment was found to decrease non-linearly with increases in percentage planned maintenance. Investment in technical training (including planned maintenance practice) was found to be low by global standards. The paper concludes that fleet availability and maintenance costs in Chilean open pit operations could be considerably improved by improving and/or developing maintenance planning standards, and investing in training personnel in planned maintenance techniques"

Jan 1, 2005

By J B. Gemmell, D R. Cooke

Recent mapping at the Kelian epithermal gold deposit in East Kalimantan, Indonesia has delineated intrusive and extrusive-phreatomagmatic breccias, their magmatic roots, and late-stage endogenous domes of a maar-diatreme complex. The Kelian epithermal system is characterised by a wide variety of mineralised and unmineralised breccias, which include tectonic, hydrothermal, phreatic and phreatomagmatic varieties. Phreatomagmatic breccias and associated igneous rocks post-date early stage alteration and mineralisation, and pre-date main stage precious and base-metal mineralisation. This study emphasises the spatial, temporal and genetic links that have been drawn between diatremes and both epithermal and porphyry systems in volcano-plutonic arcs.

Jan 1, 1999

By V. F. Hollister

The Ivanhoe district, Elko Co., Nevada, is located in the northern part of the Carlin trend of epithermal gold-deposits, but it differs from most mines in the belt in that Ivanhoe epithermal gold ores are found in 14 m.y. old Tertiary volcanic rocks as well as in the better known Paleozoic sediments. Within the Ivanhoe district U.S. Steel (USX Corp.) discovered and partly developed an epithermal gold deposit largely hosted by Tertiary rocks that, with a 167-hole program, was found to contain an open ended probable reserve of 4.0 million tons of heap leachable open pit oxide ore averaging .042 opt Au. An additional 4.0 m.t. of open pit sulfide ore averaging .048 opt Au were also developed. The U.S. Steel orebody was a blind discovery in that it just barely outcropped, and it was found by drilling through a premineral but barren cover of altered Tertiary volcanic rocks.

Jan 1, 1988

By Petrus van Staden, Dragan Milanovic, Francisco Sánchez, Eero Kolehmainen, Carlos Frias

"Currently there is no economical and viable process for on-site metal extraction from Low Grade, Complex or Poly-metallic deposits, and even more, there is not any industrial process or technology able to deal with polymetallic or bulk concentrates containing Cu+Zn+Pb base metals and also precious metals. Traditionally, metals recovery from polymetallic sulfide deposits is performed by mining, selective flotation to separate Cu, Pb and Zn concentrates, and finally, smelting/refining of those concentrates to obtain the refined metals. In many cases, selective flotation of that kind of complex ores produces low metals recovery and low concentrate quality containing impurities such as Hg, As, Bi, etc., which results in high penalties in treatment and refining charges, and consequently, worsening the economy of the mining business. Recovery of the valuable metals from Polymetallic, Complex or Low Grade ores could then be maximised by producing bulk concentrates or middling flotation products to feed novel hydrometallurgical processes, like the integral metallurgical system that is currently under development within the INTMET project. For example, producing bulk concentrates would increase more than 100% Cu+ Zn+Pb cumulative recovery versus conventional selective flotation. Founded by the Horizon-2020 EU Programme, the INTMET Project was started in February 2016 and will be running over three years. The INTMET consortium is led by Cobre Las Cruces (Spain) and integrates twelve partners from seven EU countries, and including Serbia and South Africa as well. The INTMET project represents a challenging opportunity to develop suitable technological solutions to deal efficiently with difficult, polymetallic and complex sulphide ores that are abundant in Europe and worldwide. Main activities carried out during the first 18 months of the INTMET project development includes: (i) An atmospheric leaching pilot plant having a capacity of 300 kg/h bulk concentrate which has been installed and operated continuously for nine months at the Las Cruces mine; (ii) Pressure leaching test work developed by Outotec; (iii) Bioleaching test work performed by Mintek in collaboration with MMI Bor. Prior test work was applied on bulk concentrate samples supplied from Spain, Portugal and Serbia. Some of the results of these technological developments have been very positive and are presented in this paper."

Jan 1, 2018

By M. L. Fuller

MOST commercial alloys undergo changes in phase composition after casting. This is a natural result of the fact that the alloys are not in a state of phase equilibrium as cast and phase changes will therefore take place, with more or less rapidity, in an attempt to attain equilibrium. The practical aspect of aging in zinc-alloy die castings concerns the changes in physical properties and in dimensions that may accompany aging phase changes. Harmful alterations have been reduced to a minimum and zinc-alloy die castings are being produced today that are so stable with respect to dimensions and physical properties that they are entirely suitable for most practical purposes1. In the first paper' of this series, and in this paper, aging phase changes of zinc alloy die castings have been investigated and the possible influence of these changes on dimensional changes of the castings has been evalu-ated and compared with the dimensional changes actually experienced. The change of dimensions has been selected for practical comparison in these papers because the effect of phase changes on the dimensions of a casting is directly calculable; from X-ray crystal-analysis data of the phase structure. The die-casting alloys considered contain, in addition to zinc, 4 per cent of aluminum, about 0.03 per cent magnesium, and from 0 to 3 per cent of copper. It was shown in the former paper that the eutectoidal decomposition of the beta aluminum-zinc phase, while intrinsically capable of causing a considerable shrinkage, can have very little effect on the observed shrinkage of die castings because it takes place within a few days of aging, whereas the observed shrinkage continues for five weeks. It was therefore concluded that the other existing phase change,

Jan 1, 1936

By W C. Cook, S J. Mathews, A H. Purvis

The Golden Cross Gold Mine is located at the head of the Waite kauri Ri ver, 8 km northwest of Waihi near the southern end of the Coromandel Range. The mine produces gold and silver from epithermal veins hosted by Miocene andesitic flows and pyroclastics of the Coromandel Group. Golden Cross is owned in joint venture by Coeur Gold NZ Ltd (80 per cent) and Viking Mining Company Ltd (20 per cent). Mining is by open pit and underground methods. Mineralisation in a near-surface sheeted/stockworked vein zone is mined from the open pit. The deeper Empire Vein System is mined from underground where higher grade mineralisation is restricted to generally discrete veins. The open pit stockwork zone is west of and offset from the updip trend of the Empire Vein System. The Empire (hangingwall) Vein strikes generally north-northeast and dips steeply west. Dips become subvertical at greater depth. The hangingwall vein is a well developed, generally continuous structure with relatively high gold grades. A complex footwall vein system forms shallow west-dipping offshoots to the hangingwall vein. Structure and gold grades become increasingly erratic away from the hangingwall vein. The better developed footwall veins carry economic grades and high 'spot' grades over 50 g/t Au are not uncommon. Highest gold grades are associated with tightly crustiform banded sections of quartz veins and with dark fine grained siliceous breccias. The main hangingwall vein occupies a major north-northeast trending fault structure, the Empire Fault. Footwall veining forms within subordinate splinter fault zones. There has been extensive multidirectional pre-, syn- and post-mineralisation faulting. Fault manifestation is highly dependent on host rock characteristics. The central part of the hangingwall vein and surrounding silicified country rock has been shattered by a major fault structure, the West Mine Fault, forming a poorly consolidated, blocky quartz-breccia ore zone. Away from the more brittle ore zones and associated silicified envelope, wide clay-filled shears mark the major fault trends. Development of the deposit is considered to have occurred in two distinct stages related to separate episodes of dilational jog movement on the Empire Fault. The first phase reactivated the pre-existing Empire Fault as a dilational fissure with subordinate splinters on the footwall side. The Empire Vein System (hangingwall and associated footwall veining) formed during this phase. A second phase of renewed movement with further dilation resulted in more extensive fracturing of the Empire Vein and surrounding country rock and formed the sheeted/stockwork veining of the open pit. An upwards/westward migration of the hydrothermal system is assumed but fluid pathways between underground and open pit veining are unclear. Ore extraction and mining geology methods have responded to improved understanding of the grade and structural variability, and changing ground conditions inherent in the vein system. The underground mine produces ore from flatback cut and fill, post-pillar and bench stopes. Open pit and underground ores are campaign milled through a conventional CIP plant.

Jan 1, 1993

By D. M. Maijer, S. L. Cockcroft, S. Modak, A. B. Phillion

"A comparison between hydrogen-diffusion-based micro-porosity formation and growth behaviour of two important aluminium foundry alloys, B206 (Al-Cu) and A356 (Al-Si-Mg) is presented in this paper. Specifically, the predicted pore size and pore fraction distribution of these two alloys resulting from directional solidification and identical hydrogen concentration are investigated numerically based on a model proposed by Yao et al. (2011. Met. & Mat. Tran. A. 42A, 4137–4148). This model takes into consideration the initial hydrogen content in the melt, the cooling rate, the partitioning of hydrogen between the solid and liquid phases, and the evolution in solid fraction with temperature. Due to different alloy chemistries, the activity of hydrogen in B206 and A356 are quite different, as are the solidification range and the resulting solidification microstructure. Being a primary alloy, B206 has dendritic microstructure and solidifies over nearly 135°C (505–641°C), whereas A356 contains fifty percent eutectic microstructure, and solidifies over 80°C (533–613°C). This allows a very different behaviour of micropores i.e. the effective pore radius in B206 is quite a bit lower as compared to A356, as is the pore number density. The evolution of local hydrogen concentration in liquid metal is analysed and compared for both the alloys.INTRODUCTION Over the past decades, the demand for materials with enhanced strength-to-weight ratios has significantly increased in the aerospace and automobile industries in order to improved fuel efficiency. For many automotive components, particularly shape castings, the trend is towards replacing ferrous alloys with aluminium alloys. The increase in the use of Al is primarily due to its low density, about one-third that of steel, and its relatively good strength that allows for weight reduction without reducing performance. Presently, Al-Si based alloys (e.g. A356) are the most prevalent due to their good mechanical performance in strength-to-weight ratio and excellent castability (Atwood et.al., 2000). However, superior mechanical properties can be achieved using Al-Cu alloys. For example, the alloy B206 offers a higher strength while retaining excellent ductility (Poirier et.al., 1987)."

Jan 1, 2017

By Liu Wei

In order to make clear the dissolving characteristic of the chrysocolla (CuSiO3?H2O) in the ammonia-ammonium chloride solution, a thermodynamic model of the chrysocolla (CuSiO3?H2O)-ammonia- ammonium chloride-water system is established using the exponential computation method based on both mass balance and charge balance equations. The equation group of the thermodynamic model is solved by the MATLAB Soft on PC. The condition which is favorable for dissolving high concentration of copper in solution is making out. The stable area of chrysocolla (CuSiO3?H2O) and the condition of chrysocolla (CuSiO3?H2O) converting to atacamite (Cu(OH)1.5Cl0.5) is also studied. A group of experiments are designed to validate the veracity of the results of the thermodynamic calculation.

Jan 1, 2010

By Z. Sun, H. A. Davies

"Current understanding of the mechanisms by which glassy and crystalline thin ribbons are formed in high speed continuous casting processes is considered. A computer model of the combined heat and momentum transfer during melt spinning has been developed. The influence of roll velocity and of heat transfer coefficient (between the melt and the roll) on the temperature and velocity distributions within the melt puddle is analysed and the thickness of the extracted ribbon computed. The relative importance of heat and momentum transfer under different conditions is assessed and differences between the casting of crystalline and amorphous strip highlighted.IntroductionHigh speed continuous casting of thin metallic ribbon and strip is currently of considerable interest both to metal processers and to those studying process mechanisms. The practical interest arises both from the potential economic benefits to be gained from a shorter and more energy-efficient production route and from the ability to obtain extended and uniform thin strip having a metastable microcrystalline or amorphous structure with enhanced or unique properties. The latter arise from the rapid solidification associated with the cooling of very thin sections of melt brought into intimate thermal contact with one or two rapidly moving heat sinks.The principal processes for casting thin strip include free jet, chill-block melt-spinning (GBMS) (1), melt drag (MD) (2), planar flow casting (PFG) (3) and twin-roll casting (TRG) (4). For the first three of these, all essentially variants of melt-spinning, melt flows through a nozzle onto the circumferential surface of a rapidly rotating roll, whereas for TRG the melt passes into the nip between two contra-rotating rolls. We shall be concerned in this paper with the single-roll melt spinning processes only. For these, a puddle is established where the melt contacts the roll surface and the length of this puddle l is a function of the process conditions, notably the circumferential velocity of the roll Us and the volumetric flow rate of the melt Q. The contact time between any point on the roll surface and this puddle, or residence time eR(= l /Us) determines the thickness of ribbon t extracted from the puddle. This thickness, in turn, partly governs the cooling rate T and the amount of undercooling in the melt and thus the microstructure of the solidified ribbon."

Jan 1, 1986

By W. H. Schiffbauer

NIOSH has developed an active proximity warning system called HASARD (Hazardous Area Signaling and Ranging Device) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels which are calibrated to identify levels of danger. The receiver outputs can include visual, audible, and vibratory indicators and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak, and on a highwall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed and proved to be rugged enough to withstand the harshest of production environments.

Jan 1, 2001

Like it or not, CPD is upon us. As from 1 January 2006, all registered engineering professionals, i.e. professional engineers, professional engineering technologists, professional certificated engineers and professional engineering technicians, were required to undertake CPD in order to keep their professional registration current. The rules regarding CPD have been gazetted under Government Gazette No. 28328, Board Notice 131 on 23 December 2005, and they also appear on the ECSA website?www.ecsa.co.za. For the convenience of our members they are reproduced in full in this issue of the SAIMM Journal.

Jan 1, 2006

By Iwueze Anaekperechi Rose

The International Labor Organization has declared mandatory adequate provision of safe workplace and safety for all workers in all occupations including the mining sector. Early scientists like Agricola (1559) who studied the health of Miners, found that there are peculiar health problems associated to their work and working environment. This unsafe working condition was one of the major factors that resulted to the Industrial revolution in England and eventually led to the establishment of regulations and laws guiding operations in all workplaces and workers in England and all over the world. Recent studies by Heinrich suggested chains of events of safety issues in the mining sector. Occupational injuries, accidents and ill health have huge social and economic implications on workers, their families and communities. Top mining top issues are respiratory diseases, noise, explosives, ventilation, fire, and explosion. However, one of the principal mechanisms for achieving Occupational Health and Safety (OHS) goals and mapping the future is government regulations of employers. In Nigeria, the situation is not different; mining operations are equally hazardous and have far reaching implications. In 1995 the Ministry for Solid Minerals was established to focus on the development of other categories of mineral products ranging from gold, coal, uranium, and tantalum deposited across the country. Prior to this an Act of Parliament Act Cap 121 of 1946, was in place to regulate amongst other contents mining safety. This was subsequently reviewed following the incidence of Lead poisoning resulting from small scale miners processing gold ore highly contaminated with lead in Zamfara state (northern Nigeria). Hundreds of children died as a result of exposure to lead poisoning, it was clear that the regulations were not sufficient (details to be discussed). However, advances have been achieved in mining engineering since then. A review team was constituted to provide a more stringent law to regulate mining operations in Nigeria. The strategies for mapping the future of OHS in mining engineering will employ amongst others setting and adopting ISO/ILO standards and enforcement; providing technical assistance; and establishing sustainable developmental structures as surveillance and compensation. The management systems approach was also developed as a result of cases of accidents. The accepted international standards guidelines and requirements will be proposed. Furthermore in mapping the future for Mining Engineering, it is suggested that most countries have their own management strategies and legislation to improve safety of workers through greater consistency and efficiency of OHS programs. Some American researchers came up with the Safety Engineering Model. The Australian Mining Council of mineral and petroleum resources after the Catastrophic Maura Disaster developed the National Mine and Safety Framework. In Canada, after the Hillcrest mine disaster in 1914, Allan shaft coal mine catastrophe in 1918, Westray mine explosion in 1992 and other disasters, Occupational Health and Safety Act R.R.O 1990 was sufficiently developed to provide adequate safety conditions and standards. In Nigeria after the disastrous Zamfara lead poisoning, which claimed the lives of hundreds of children due to exposure and lack of appropriate safety measures, stringent measures were developed by the federal ministry of Justice to address and regulate mining process in Nigeria.

Aug 1, 2013

The Bureau of Mines, through its Minerals Availability Program (MAP), investigates the mineral supply potential of the United States and market economy countries (MEC's) for a number of minerals considered essential to the U.S. industrial base. Major activities include identification of important mines and mineral deposits, estimation of their mineral resources and production costs, and availability and sensitivity analyses. Products include data print-outs of geological and engineering information, discounted- cash-flow rate of return (DCFROR) analyses of individual mining operations, commodity availability appraisals, and analytic services to Government agencies. These products are used in assessing the mineral supply position of the United States: in setting priorities for research aimed at reducing production costs and minimizing adverse environ- mental impacts and regulatory compliance costs of mining and mineral processing operations; and in formulating and evaluating Government policies that affect minerals. Bureau MAP data and analyses have been provided to the executive and legislative branches to aid in consideration of trade, tax, and stockpile policy issues. A study of the economic potential of selected seabed mineral resources supports the regulatory responsibilities of the Department of the Interior in the U.S. Exclusive Economic Zone. Analytic studies of mineral project viability, industry competitiveness, and import dependencies were also undertaken for, or in cooperation with, U.S. and foreign government agencies, industry and trade organizations, and international lending institutions.

Jan 1, 1987

Aluminum Production. -By October 1, Aluminum Company of America will restart a 35,000-ton-per-year unit at its aluminum smelter at Rockdale, Tex., restoring that facility to its full capacity of 325,000 tons annually. Primary Ingot Price Increase. -Most U.S. aluminum producers in mid-September were quoting a price of 72 cents per pound for primary aluminum ingot. On September 19, Kaiser Aluminum & Chemical Corp. announced that it would increase the price of primary aluminum ingot 4 cents to 76 cents per pound.

Jan 1, 1980

By G. Arpa

Ventilation survey using tracer gas measurement is one of the techniques for mine ventilation design, monitoring and investigation of movement of fresh air and contaminants. However, there has been little research into using both tracer gas monitoring and numerical simulation. In this research, tracer gas technique was used for quantitative assessment of airflows through narrow vein shrinkage stopes with various opening shapes and friction factors. SF6 was used as a tracer gas to monitor airflow through three narrow vein shrinkage stopes in order to obtain diffusion concentration curves against elapsed time. The mine ventilation simulator, MIVENA Ver.6, was used to construct the entire ventilation network of the mine to monitor airflows through the stopes. The diffusion concentration curves against elapsed time were simulated with a numerical model. The result shows that the concentration-time curve is unsymmetrical and is skewed to the front of the flow direction. From the results of history-matching between the measured and the simulated curves, volume flow rates of airways and stopes were evaluated. Importantly, the tailing effect of the concentration-time curve between the measured and simulated is greatly improved by reconstructing an equivalent airflow route to represent unused mine openings, dead end drives and other open spaces. Finally, it can be concluded that openings, dead end drives and other open spaces have no relation on flow rates, but affect the airflow quality provided from the inlet portal as shown by tracer gas diffusion characteristics.

Jan 1, 2009

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 22nd August, 1973. Dr J. P. Hugo (President) was in the Chair. There were also present 64 Fellows, 20 Members, 5 Associates, 3 Students, and 34 Visitors, making a total of 126. The President declared the meeting open at 4.05 p.m. OBITUARIES The President: It is my sad duty to announce the death of the following members of the Institute C. Boocock, R. J. G. Moore, M. P. Pearse, and A. I. Sussman, all Fellows, and W. T. Dalling, a Life Member. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I ask you to rise and observe a few moments' silence. MINUTES Die President: Item twee op die agenda is die bekragtiging van die notules van die jongste Algemene Vergadering van die Instituut. Daar die notules in die Augustus uitgawe van die Joernaal gepubliseer is, vra ek u toestemming dat dit as sulks bekragtig word. Toestemming verleen. WELCOME TO VISITORS The President: It is my very great pleasure to welcome all the distinguished guests who have honoured us with their presence this afternoon; in particular, a hearty word of welcome to the Honorary President of the Institute, Mr Plumbridge, the President of the Chamber of Mines. You are doubly welcome here, sir, and we thank you for your presence. Also to that old member and stalwart, the Honorary Vice-President of the Institute, Mr Tommy Gibbs, the Government Mining Engineer-you're very welcome, Mr Gibbs. Then, we are particularly privileged this afternoon to have an Honorary Member with us, the Minister of Mines for Rhodesia, Mr Dillon. You will recall that he honoured us with his company last year. Mr Dillon, we are very appreciative and hope that this is now a standing arrangement. We are also honoured by the presence of some thirteen Presidents, Vice-Presidents, or Chairmen of our sister scientific and technical organizations. I shall rapidly read their names, but they must all feel assured that they are very welcome here today. Firstly, one of our own Past Presidents and members, Mr Geoff Goode in his capacity as President of the Associated Scientific and Technical Societies of South Africa; Mr L. R. Robinson, President of the South African Institution of Mechanical Engineers, and Mrs Robinson; Mr G. Goedhals, President of the South African Institute of Electrical Engineers ; Dr Antrobus, President of the Geological Society of South Africa, and Mrs Antrobus; Mr T. V. Dean, Vice-President of the Institute of Land Surveyors of the Transvaal, and Mrs Dean; Mr R. M. Stroh, President of the Mine Ventilation Society of South Africa; Mr Ken Steele, President of the Association of Mine Managers, and Mrs Steele; Mr Mike Gericke, President of the South African Council for Professional Engineers; Mr R. G. Matthews, President of the Institute of Mine Surveyors of South Africa; Mr P. H. Pettifor, President of the Institute of Production Engineers, London, and Mrs Pettifor ; Dr Nico Stutterheim, Chairman of the South African Institute of Chemical Engineers, and Mrs Stutterheim; Professor F. A. van Duuren, Chairman of the Engineers' Liaison Committee in Pretoria; also, I haven't spotted him but I trust he is here-Mr Alex Bain, who is Chairman of this Institute's Witbank/Middelburg Branch. To one and all, ladies and gentlemen, a hearty word of welcome. Not last on our list, a word of welcome to Mr Eric Boden, the Manager of A.S. and T.S. We also have with us I trust, Dr Deist, and his good lady-Dr Deist will be figuring in our proceedings later this afternoon. Also Mr Barcza and Mrs Barcza. Mr Bareza, a former President of the Institute, also has a task to perform. Then, I hope two of our student prize winners are here-Mr Beetge and Mr Painting. Then we also have Mr Roberts, who is welcome in his capacity as co-author with Dr Deist. Then, last of all, a hearty word of welcome to Dr Helen Glen (I am not sure whether she has arrived yet, but she is certainly due to come)-the new Honorary Editor of the Institute's Journal. MEMBERSHIP The President: I have pleasure in announcing that, their names having been published in accordance with By-law 5.2.2, the following have been elected by Council to membership in the following grades Fellows: W. G. Jayes and F. K. Wright Members: D. W. Penman, A. W. Bryson, and D. L. Gibbs Graduates: R. J. Adey, J. P. Bond, R. C. Dunne, G. M. Entwhistle, J. M. Rendu, J. P. S. Turner, and A. P. van Jaarsveld Associates: A. Ellis, B. R. Hambly, A. J. Johansen, and G. W. Tregoning

Jan 10, 1973

By Yajie Wang

High horizontal stress and its adverse effects on longwall gate entries have been witnessed in many US coal mines for the past years. It can cause cutter roofs and leads to roof falls either in the headgate or tailgate entries depending on the relative orientation of the panel to the maximum principal horizontal stress. Underground observations have shown that if the maximum principal horizontal stress is perpendicular to the panel entries, the roof is in the worst condition and if the maximum principal horizontal stress is parallel to the entries, the entry is in the best condition. However, little has been done about the high horizontal stress effects on panel entries subject to different orientations of high horizontal stress. In order to design a longwall panel and control the roof effectively, the redistribution and concentration of high horizontal stress field must be fully understood. Using 3-D finite element analysis, this paper presents the high horizontal stress redistribution and concentration for a retreat longwall face with different orientations of high horizontal stress. Based on the results, possible roof failures for different orientations of high horizontal stress are analyzed. A panel design criterion is recommended.

Jan 1, 1996

By Leith Sharp

I was confronted with a profound dilemma as an undergraduate engineering student at the University of New South Wales in Australia in 1992. I had been taught that our planetary life-support systems were in a state of alarming decline by an institution that operated as if what the faculty was teaching was irrelevant. Lights were left on in empty overcooled classrooms, recycling bins were nonexistent, lawns were maintained using pesticides and herbicides, diesel trucks spewed fumes as they passed on their way to drop off chlorine-bleached virgin paper. This disconnect was very alarming to me. While it was obvious that universities should play a leading role in teaching and researching sustainability issues, I wondered how it could be possible to make widespread institutional changes to meet the demands of environmental sustainability when it was not even being done in the very university sector where these ideas were being promulgated. If universities would not change, then who can and who will, I wondered? To a growing number of people, the idea of teaching sustainability without demonstrating it is highly problematic. It is also widely believed that the ability of the higher education sector to reform its own practices is an important indicator of humankind?s ability to address the global environmental imperative across all sectors of society. These sentiments have helped fuel what is now referred to as the campus sustainability movement, a movement dedicated to transforming our campuses into living laboratories for the demonstration and practice of environmental sustainability.

Jan 1, 2010

By Robert E. Barieau

A list of 163 references to original experimental PVT data on helium is presented for the period 1895 to 1968. The list is complete as of the start of the Helium Centennial Year, 1968, to the best of the author's knowledge. Citations were keypunched for easy updating and are listed alphabetically by author.

Jan 1, 1968

By George S. Rice

In 1911 the Director of the United States Bureau of Mines instructed the chief mining engineer of the bureau , during an investigation of coal-mine safety conditions in Europe, to ask the directors of the various mine-experiment stations whether they would favor a European conference . The majority of the officials in immediate charge of experiment stations favored the plan , and Victor Watteyne, inspector general of Belgium, suggested that the United States call such a conference to be held immediately after the Eighth International Congress of Applied Chemistry, which was to assemble in New York on September 3, 1912 . Accordingly, invitations were issued by the United States Government to those countries having mine-experiment stations , namely, Austria-Hungary, Belgium, France, Germany , and Great Britain, and to those that contemplated the establishment of such stations , Canada and Mexico . All but Great Britain and Canada accepted ; Mexico designated a representative , who later found it impossible to come. The Government of Great Britain in declining, expressed regret at its inability to accept ; an informal statement was made that the opening of the experimental gallery at Eskmeals , England , occupied the attention of the officials in charge . Delegates were appointed by their respective Governments as follows: Austria-Hungary, Julian Czaplinski , royal mining engineer. Belgium, Victor Watteyne , inspector general of mines . France, J. Taffanel, director of the Lievin experiment station . Germany, Carl Beyling, bergassessor, director of Dortmund experiment station. United States , Charles E. Munroe, consulting explosives expert and George S. Rice, chief mining engineer of the Bureau of Mines . Subsequently Mr. William O'Connor , a mining engineer and mine operator of Wales , who opportunely appeared at the Pittsburgh station with letters of introduction from the South Wales Institute of Engineers and from prominent mining officials of Great Britain , was unanimously invited to take part in the meeting as an unofficial representative of Great Britain . Messrs . Beyling, Taffanel , and Watteyne were met in New York on September 3, by George S. Rice, who accompanied them to Washington, where they were welcomed by Director J. A. Holmes , of the Bureau of Mines , and where , with the delegates to the Eighth International Congress of Applied Chemistry , they were presented to President Taft . Mr. Taffanel was unfortunately called back to France just before the scheduled time of the conference on account of a mine disaster ; the other delegates , including Mr. Czaplinski , convened at Pittsburgh on the morning of September 14. Mr. Rice, representing the Director of the Bureau of Mines , acted as temporary chairman , and called the meeting to order.

Jan 1, 1914