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By J. M. GLEDHILL

(Washington Meeting, May, 1905.) A Discussion of Mr. J. M. Gledhill's paper, read by title at the Lake Superior meeting, but presented first at the New Yolk meeting of the Iron and Steel Institute (October, 1904), and here published under a mutual agreement. Between the two Institutes. Discussion. MR. E: WINDSOR RICHARDS, Past-President, said that at a recent meeting of the Institution of Mechanical Engineers a paper was read on tool steel, and he called the attention of the members to the high-speed tool steel at the Bethlehem Works. They would have the pleasure of seeing those wonderful works and would see 60, 70, 80 and 100 tons oil lathe with half-a-dozen of these high-speed tools running. PROP. H. M. HOWE (Columbia University) said that they all looked upon these high-speed tool steels as of very great importance, particularly to the machine shop. One point occurred to hire : Had it really been shown that Swedish steel is necessary, or better than equally pure steel that is not Swedish; and is cemented steel really necessary, and is there any advantage in using that, rather than equally pure open-hearth steel'! It might be well if the author could indicate the kind of evidence on which lie bases his assertion that it is necessary to have cemented Swedish steel. Many were hoping for the development of high-speed steels from elements which exist in great quantities, such as silicon, manganese and chromium, rather than from rarer metals like molybdenum, vanadium and tungsten, the supply of which is likely to be soon exhausted. If the high-cutting speed was to last more than a generation, it. seemed to him that they would have to draw upon the common ele¬ments and not upon the rare ones. MR. Tom WESTGARTH (Middlesbrough) said he fully appreci¬ated what had been said about the advantages of using high-speed steel, because great benefit had been derived from the

Mar 1, 1905

By Frank M. Vodoklys

This is the final report on Contract H0220049 covering the period from 27 April 1972 to 30 April 1974. The objective of the contract was to develop and evaluate materials and methods to achieve post explosion identification of explosives reliably and economically through the use of phosphor coded grains incorporated into the explosive during its manufacture. A coding system of two spotting phosphors and seven coding phosphors was successfully developed during the execution of the contract. The ability of the coded grains to survive detonation in many different types of explosives was demonstrated and the complete code was extracted from a single 100 micron post-explosion fragment. A method was established for testing grain strength to correlate with field test results and an optical system was designed for extracting the code from the grains. Also in fulfillment of the contract requirements a laboratory method for manufacturing the coded grains was established and ten one-pound samples, each with a different code, were fabricated. Finally, a method was developed for applying a coating of polyethylene to the grains to prevent sensitization of the tagged explosives and the ten one-pound samples were coated and delivered to the Bureau of Mines.

Jan 1, 1974

By Daniel Antonio Kapper Fabricio

O módulo de tenacidade é um parâmetro que representa a energia absorvida por um material até a ruptura, e é uma variável importante para avaliar se o material sofrerá fratura quando em serviço. A tenacidade é determinada através da área sob a curva tensão-deformação de engenharia, a qual é difícil de ser calculada analiticamente. Assim, o presente trabalho propõe a utilização de métodos numéricos para o cálculo do módulo de tenacidade através de planilhas eletrônicas. Como resultados são apresentados o procedimento desenvolvido e os valores obtidos na estimativa da tenacidade de uma amostra, assim como a comparação do resultado com o valor calculado analiticamente e com o valor calculado através de um método simplificado. Conclui-se que o valor numérico calculado é tão próximo do verdadeiro quanto maior o número de pontos obtidos na curva tensão-deformação de engenharia, viabilizando a utilização desse método na estimativa da tenacidade de uma ampla gama de materiais. Além disso, o método numérico pode ser usado na determinação de outras propriedades calculadas através da área sob curvas.

Aug 7, 2018

By Loren R. Anderson

A probabilistic slope stability computer model was developed at Utah State University and independently evaluated by CH2M Hill Consulting Engineers as a design and analysis tool. Volume I of this report describes the model and Volumes III and IV are users manuals for the computer programs. This volume (Volume II) constitutes the report by the CH2M Hill. It includes a description of a field investigation and stability analysis of an existing tailings dam. Based on the results of the analysis, the tailings dam was evaluated for redesign using probabilistic considerations. Conclusions are made regarding the usefulness of the model as a design tool.

Jan 1, 1982

By A. R. House, G. W. Shepherd

Newmont USA Limited owns and operates the Phoenix Mine near Battle Mountain, Nevada, USA. The existing milling facility has operated since 2006 (House, 2010). Following the startup of the milling operation, and coupled with the upswing in the copper market, Newmont realized that Phoenix had no process option to treat transition and oxide copper ores. This meant that potentially revenue generating ore would be mined as waste. With no system in place to treat the transition and oxide copper, work began to determine the most feasible approach. After evaluating multiple options, the flow sheet was set for a runof- mine (ROM) heap leach pad and solvent extraction/ electrowinning plant (L-SX/EW). This paper will discuss the eight years of successes and challenges with developing the copper L-SX/EW plant and achieving commercial production of copper cathode.

Jan 1, 2014

By M. Leroux, P. Lacombe, S. R. Rao, J. Y. Kim, J. A. Finch, G. Labonté, N. Macminn, M. Ounpuu

"Laboratory investigations on two complex ores, the A1 zone ore from Les Mines Selbaie and the Lyon Lake ore from Mattabi Mines Ltd. (Division of Noranda Minerals), have been carried out to determine some of the main variables in collectorless flotation. In particular, the effect of pulp potential (controlled by gas composition), conditioning time, pH and grinding media have been studied.Chalcopyrite showed the greatest response to collectorless flotation among the four major sulphide minerals present, followed by galena. Flotation of sphalerite was variable from minimal to important depending on the mineralogy and the pre-treatment performed. Appreciable silver recovery was achieved collectorlessly for the Lyon Lake ore while it could not be achieved for the A1 zone ore of Les Mines Selbaie. It appears that the difference between the two ores is related to silver's predominance as tetrahydrite in the Lyon Lake ore while it is as argentite and native silver in the A1 zone ore.The response of the ores to collectorless flotation is strongly dependent on the pulp potential, Ep, and pH. Using different gas compositions and different conditioning times it was found that collectorless flotation occurs when Ep is +195 to +295 mv (vs SHE). The actual on-set potential for collectorless flotation is dependent on the ore. A too high potential or prolonged oxidation leads to a decrease in selectivity. Some other factors were examined, notably the effect of pH and the type of grinding media on the selectivity achieved in the laboratory.Preliminary results from a plant trial at Mattabi Mines Ltd. confirmed that collectorless flotation occurs and that it is preferential for chalcopyrite and to a lesser extent galena. Collectorless flotation was not attempted at Les Mines Selbaie. However, examination of the distribution of collector between the different addition points in the copper circuit suggests that it may be present."

Jan 1, 1990

Laboratory and pilot plant investigations aimed at recovering gold as an electroformed sheet from gold eluate and gold leach solutions and slurries are discussed. The electrolytic test work undertaken makes use of high surface area electrodes, in particular nickel-chrome foam metal and activated carbon, as well as ultrasonic activation. The process involves initial gold electrowinning (or adsorption onto activated carbon), followed by gold electroforming, both operations being carried out in a specially designed reactor. The pilot plant work mainly involved the treatment of gold eluate solutions from a South African gold mine containing 600 mg/L Au: some tests were also carried out on gold leach solutions containing 6 mg/L Au. In the former case, very efficient gold extraction onto the foam metal cathode was achieved using electrolysis combined with ultrasonics. The polarity of the gold-loaded cathode was then reversed and, using a replacement electroforming electrolyte, gold was electroformed in situ onto a polished stainless steel mandrel, from which gold sheet was subsequently removed. In the case of leach solutions, pilot plant tests confirmed laboratory findings that in the presence of calcium (resulting from the lime used during the leaching process) no electrowinning is possible. Laboratory tests showed, however, that when sodium (in the form of NaOH or Na2CO3) is added to the leach solution, electrowinning can indeed take place. Alternatively, if a special activated carbon electrode is used (without current), the non-ionic calcium aurocyanide complex is adsorbed on to the activated carbon. When a gold-loaded activated carbon electrode is made anodic in a gold electroforming electrolyte, gold electroforming is feasible, although the efficiency is very low. The possible implications of these developments for gold recovery are further examined.

Jan 1, 2007

By D. Akers

Many of the trace elements found in coal are associated with mineral matter, making it possible to remove them by physical coal cleaning. As part of work funded by the Electric Power Research Institute, both conventional and advanced coal cleaning processes were found to provide large reductions in the concentration of many trace elements that, if released into the atmosphere, are considered to be potentially toxic or environmentally harmful. Advanced physical cleaning technologies appear to provide greater reductions than conventional technologies. Chemical cleaning processes may also remove many trace elements, possibly including organically-bound elements such as beryllium. Care must be taken in the disposal of coal cleaning plant refuse because oxidation and leaching of this material can create highly acidic leachate and many trace elements are mobile in an acid environment. Laboratory leaching procedures are potentially useful in determining the degree of risk of water contamination by trace elements should an acid environment form.

Jan 1, 1992

A record $18.7 billion worth of metals, non- metals and fuels was produced in the U.S. during 1962, according to a year-end estimate from the USBM. The 1962 total value, based on preliminary statistics compiled by the Bureau, was nearly $600 million more than in 1961. Most minerals gained both in value and volume of production during 1962 according to information collected by the Bureau. All mineral fuels except anthracite showed increases. Among nonmetallic minerals- other than fuels-gains exceeded losses by two to one. Metal production held steady as gains and losses balanced.

Jan 2, 1963

By H Zhang, A Lawrence

To accommodate the fast growing need for services in Singapore’s Marina Bay downtown area, Marina South, the construction of a common services tunnel (CST) was required. The CST includes various services such as telecom cables, power lines and water pipes. A deep excavation and temporary earth retaining system (TERS) was required to facilitate the construction of the tunnels. Marina Bay is reclaimed land over thick soft marine clay which is likely to be still consolidating. The deep soft marine clay poses a big challenge for deep excavations in downtown areas where highways and sensitive structures are close by. This paper presents a case study of part of the CST Phase 1B and 2 at Marina South, in particular a 26 m deep excavation supported by a 46 m diameter temporary caisson. The construction started in late 2006 and the basic structure was completed in early 2011. The caisson was formed by 1.0 m thick overlapping diaphragm wall panels with a capping beam and three ring beams at different depths. Two-dimensional finite element analyses were conducted to predict the ground settlement, lateral displacement, bending moment and hoop stresses in the diaphragm wall and ring beams during different excavation stages. A comprehensive instrumentation and monitoring scheme was established to verify the design predictions, control excavation safety and trigger the contingency plan to protect public safety. The impact of construction activity, unbalanced temporary stockpiles and adjacent deep excavation for a mole removal will be discussed.CITATION:Zhang, H and Lawrence, A, 2014. A case history of a deep excavation in a big circular shaft in Singapore marine clay, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 581–588 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M Bellamy

The DeGrussa copper deposit was discovered by Sandfire Resources in April 2009. Construction of the 1.6 Mt/a concentrator, open pit and underground mining operations commenced in March 2011 with first concentrate production achieved in October 2012. Over the next ten years, DeGrussa grew to include both the DeGrussa and Monty underground mines, establishing itself as one of the world’s premier copper producers with total production of 663 000 t of contained copper by the time the mine closed. Final ore was trucked from Degrussa on 5 October 2022. This paper examines the mine closure experience from both a planning and operational perspective. The paper provides an overview of the site’s mine planning process including the factors involved in determining the end of the mine life and how this was tracked and communicated in the lead up to the end of mining operations. It will also look at some of the specific operational aspects involved in maintaining steady state production all the way through to the last day while facing increasingly challenging conditions. These factors, along with the external factors faced by most of the industry such as labour shortages and COVID related disruptions, contributed to making it an interesting journey to the end of operations at DeGrussa.

Mar 29, 2023

By Frank P. Frandina

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. The project involves clearance improvements to twenty-eight tunnels, twenty-one of which require structural modification. With construction of the first Package of tunnels just underway at press time, this paper summarizes the program implementation from design through the initial stages of construction.

Jan 1, 2008

By M Ireland

Extensive use of diesel-powered mobile equipment in modern mines for materials handling, such as load-haul-dump machines, constitute a significant source of heat, exhaust gases and diesel particulate matter. Provision of sufficient quantities of fresh, cool air are required to remove such atmospheric contaminants from the environment for miners, particularly at depths where ventilation constraints and associated operating costs have an increasingly adverse impact. An alternative solution to diesel equipment to combat economic, environmental, social and health challenges, are battery electric vehicles (BEV), with the potential to expand production and substantially reduce ventilation and cooling demand, subsequently reducing operating costs. In this context, this paper focuses on the introduction of a battery electric loader to a diesel fleet at one of the deepest underground mines in Australia, the CSA Mine, a high-grade copper operation in Cobar, New South Wales. Analysis of a trial battery electric loader compared to existing diesel machines is performed with regards to infrastructure, technical and operational issues. Key benefits of battery electric vehicles over conventional diesel-powered vehicles are discussed, including lower energy consumption and greater efficiency, reduction of emissions and heat, reduced need for ventilation and lower operating costs. Challenges of introducing BEVs into an operation, along with the results from the comparative study are addressed under impacts to energy consumption, equipment selection, effects on ventilation and cooling, mine design and economic viability for future fleet implementation scenarios whilst meeting production targets.

Mar 29, 2023

By Walter D. Holland

This is one of a series of instruction guides developed to help instructors present health and safety training courses to workers in the coal mining industry. This course is intended for training those, usually the safety officers, who perform surveys fur inhalation contaminants in above ground work areas. The handbook entitled ?Handbook for Surveys of Inhalation Contaminants in Above Ground Coal Mining and Processing Work Areas? (NTIS #PB-243-35";) is used as a manual for the course and as a prime reference when performing the actual surveys or interpreting the sampling results. There are six experiments for the students to perform during the course to familiarize them with the sampling devices routinely used during the surveys.

Jan 1, 1976

The U.S. Bureau of Mines conducted a laboratory study to determine what effect use of water-jet-assisted cutting has on frictional-ignition suppression. A single bit with a steel tip, installed on a rotating drum, repeatedly made 22-in-long cuts in a block of Berea sandstone. The drum was operated in an enclosure that contained an explosive methane-air mixture. High-pressure front-mounted water jets operating at 2,000 to 5,000 psig and low-pressure rear-mounted sprays operating at 80 psig were used; the number of ignitions that occurred with each type of spray was compared. The rear-mounted spray was more effective for preventing frictional ignitions than the front-mounted water jet.

Jan 1, 1989

By B. K. Shibler

As a part of the Bureau of Mines' intensive; 'investigation of domestic manganese deposits, ore-dressing studies were conducted on three samples of oxide and silicate manganese ores from various Wyoming properties. The samples wore as follows: 1. A 2-ton sample of ore was obtained by a Bureau engineer during examination of the Caulkins-McGuckin property in the center of Crook County, 10 miles north of Sundance, Wyo. The ore body was described as a vein deposit in rhyolite porphyry. 2. The J. B. C. Mining Co. submitted a 1-ton sample of oxide manganese ore from a property located 44 miles northeast of Rock River in Albany County, Wyoming. 3. A 1-ton sample of oxide-silicate-ore was obtained by a Bureau examining engineer from the Gheen property in the northeast corner of Washakie County, Wyo. The ore body was described as a replacement deposit in a country rock of silicified limestone. As the samples differed widely in physical and chemical characteristics and also in their response to methods of concentration, ore from each property was considered a separate ore-dressing problem.

Jan 1, 1949

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages.With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By Allan Herse

"The years following World War II were nation building years in Australia. Soldiers returned from the European and Asian theatres of war sparking a major infrastructure construction boom. Dams and highways were built to keep up with the growth of towns and cities, which were bursting at the seams, not just from the returning soldiers settling down with their families but also from the many waves of refugees from war torn areas around the globe.The demand for electricity generation and distribution required for the growing population sparked the expansion of the national power grid with new high-voltage transmission towers appearing across the landscape. However, with an original design life of 50 years, those transmission lines constructed in the 1950s are nearing, or are at the end of, their anticipated service life.In recent years, the Australian power distribution network has changed from a period of high construction activity in greenfield high-voltage lines to a period that is now focused on reducing cost and maintaining existing assets. Replacing aboveground structural members and electrical components is relatively simple even under live conditions. However, the replacement or repair of tower foundations, many of which are in remote locations, has been a problem that has caused difficulties for power utilities trying to operate on a budget while also avoiding costly and unpopular power outages. With thousands of miles of aging transmission lines needing life extension work, Piling & Civil Australia (PCA) has developed a patented system of upgrading the foundations with micropiles while under live-line conditions without requiring costly outages. The system is seen as revolutionary by power utilities, allowing the utilities to extend the life of their existing assets until demand increases to warrant the construction of a new line. PCA has been working on a potential solution with Powerlink Queensland for the past 5 years to develop a quick and cost-effective foundation replacement system that can extend the life of its existing asset base anywhere from an additional 5 years to 50 years.With design support from Quanta Subsurface, USA, PCA recently completed the foundation replacement of 26 lattice tower foundations in the Townsville region of North Queensland. Using a steel bracket (patent pending) to connect hollow bar micropiles to the lattice towers, the installation techniques that were developed enabled the micropiles to be installed within a tolerance of less than about 3/8 in (10 mm) through the existing steel grillage foundation while maintaining live line conditions. The project was an Australian first and a trial by Powerlink for wider use within its network, and it was delivered on time and within budget at one tenth of the cost of traditional methods."

Jan 1, 2017

By K. Yathavan

Fracturing of rock at low stress levels can be a source of unexpected problems in rock engineering: • the resulting instability can be a safety hazard; • in very brittle rocks it may be associated with violent failure of the rock and strainbursting (rockbursting); • it usually leads to an unexpected requirement for rock support, with time and cost implications; • in rock boring projects, it may result in fracture of the rock ahead of the bored face and in the walls of the bore behind the face. This may lead to cutter head vibration, increased cutter wear and consequently decreased performance and increased costs. Examples of situations in which fracturing of rock at very low stress levels has been observed will be described. This will include details or estimates of the in situ stress magnitudes and the rock strengths involved. La brisure de roche sous faibles contraintes peut être l’origine de problèmes inattendus en génie minier : • L’instabilité résultante peut devenir un danger • Elle peut provoquer des éclatements violents des roches fragiles • Elle nécessite souvent une infrastructure de soutien de la roche, ayant des implications sur les coûts et les délais • Les forages de la roche peuvent provoquer une brisure de celle-ci au niveau de la surface forée mais ainsi à l’intérieur de la roche, causant parfois des vibrations et une fatigue de la tête de forage, induisant une baisse de performance et un accroissement des coûts. Nous avons décrit ci-après des exemples de situations de brisure de roche sous faibles contraintes. Cette description comprend des détails ou des estimations des forces et des contraintes impliquées. Cette étude représente la base du travail de recherche effectué sur le phénomène. ißbildung im Gestein unter niedrigen Stressbedingung kann eine mögliche Ursache sein für unerwartet auftretende Probleme in der Felsmechaniklehre: • Die resultierende Instabilität stellt ein mögliches Sicherheitsrisiko dar; • In sehr sprödem Gestein kann es verbunden sein mit einem plötzlichen und gewaltsamen Zerfall des Gesteins; • In den meisten Fällen ist eine nicht eingeplante Gesteinsabstützung erforderlich, und damit ein Zeit- und Kostenaufwand verbunden; • Bei Bohrungsprojekten kann es dazu führen, daß es während des Bohrvorganges zu einer Rißbildung im Gestein hinter und vor der gebohrten Felswand kommt. Dies kann Bohrkopfvibrationen, eine erhöhte Bohrkopfabnutzung und folglich eine Bohrleistungssenkung, sowie Kostenerhöhung zur Folge haben. Das Phenomen von Gesteinsrißbildung unter niedrigen Stressbedingung wird anhand von einigen dokumentierten Beispielen erörtert. Diese beinhalten zudem Details oder Schätzungen bezüglich der Stärke des in situ Stressfeldes, sowie der gegebenen Gesteinsstärken. Die mit diesem Beitrag dokumentierten Ergebnisse formen eine Grundlage zur weiteren Forschung dieses Phenomens.

Jan 1, 2003

Fine Gravity Separation in the Reflux Classifier, Exploiting a High Shear Rate, Laminar Flow Mechanism The Reflux Classifier is used in the gravity separation of particles over a broad range of particle sizes. The device consists of a fluidised bed zone, with a system of parallel inclined channels above. The inclined channels provide a significant hydraulic advantage over conventional fluidised beds via the so-called Boycott Effect (Boycott, 1920). This paper describes a new advance in fine gravity separation based on the high shear rate and laminar flow profile that arises when closely spaced inclined channels are deployed. As reported recently (Galvin et al, 2009a), a powerful density based separation mechanism develops from this arrangement, suppressing the effects of particle size. In this paper we focus on two areas, firstly the application of the separator in the laboratory for batch fractionation of particles of varying size and density to determine the grade recovery curve and hence the liberation, and secondly the step change in separation performance achieved on a continuous steady state basis when closely spaced inclined channels are used. The variation in the separation density with particle size decreases significantly, and the Ecarte Probable Error (Ep) remains at low levels over a broad size range.

Sep 13, 2010