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By Richard H. Bares

This report describes the purpose and application of seventeen statistical and mathematical procedures used in a series of studies made in the project ?A Systems Approach to the Reclamation of Strip-Mined Areas in North Dakota". The objective is to help readers better understand the utility of these procedures.

Jan 1, 1982

By A Annor, L J. Chen

The production of paste backfill has typically been accomplished through the adaptation of existing technology. Thickeners and disc filters have several drawbacks when applied to production of tailings paste backfill. Personnel at CANMETÆs backfill research laboratory in Sudbury, Ontario, Canada have been carrying out research into and development of methods to produce paste backfill using total mill tailings since 1991. Using a silo for production of paste is not a new concept but has been refined to a marketable level. This technology is based on a fluidization principle that assists in settling the tailings to an homogenous state in a silo. Other developments include patented de-watering technology for use in the silo to speed the settling of the solids to a suitable solids content, optimisation of silo geometry, and instrumentation related to paste backfill production and transportation. The advantages to fluidisation technology are in reduced capital cost, reduced operating costs and in the environmental benefits of using full plant tailings over classified tailings or alluvial aggregates. Another major advantage is in the ability of this technology to be retrofitted to existing hydraulic backfill plants to further reduce capital cost. This paper details the development of the new technology as well as the associated cost savings over other technologies. It will also look at the research and development of unique components that make this technology work.

Jan 1, 1998

By Freddy Syvertsen

"During the past two years the Association of Norwegian Foundries in Norway has been running a project in evaluation of CAD/CAM systems for foundries.In this work we have had a closer look to the various steps from drawings to the finished castings. On this background we have made a specification of the special needs in the foundry process. The main content of this paper is a presentation of this specification.Some CAD/CAM sytems have been compared with the specification and a summary of the result is presented.In the project we have also had a closer look at some systems where we actually have tried the user interface and some of the possibilities in the systems. In this way we have gained a more detailed knowledge of the systems and we have also got some experience in NC-machining from the systems.IntroductionThe development of CAD/CAM systems has taken place with almost no interaction with the foundry business. This becomes clear when you are having a closer look at the systems. Most of them have not the possibility to describe the complex sculptured surfaces that is often found on castings. The people developing the software, have paid little or no attention to the problems arising when a geometry is going to be transformed for the casting process. Among the problems are the decision of where to place the parting line and to adjust the draft angle. These problems must be solved properly to be able to withdraw the model from the sandmould. In die casting the problems must be solved to be able to get the casting out of the die.In Norway some companies have been developing CAD/CAM systems for several years, with limited interest in foundry problems till 1983. To present the special foundry problems to them a specification of the needs was made that year. Another reason for making this specification, was to compare it with the CAD/CAM systems on the market (1).Design of castingsGeometry transferThe foundries in Norway are small units with almost no design of their own casting products. They are subcontractors receiving paper drawings and limited informations about the product from the mechanical industry both in Norway and in other European countries. This is going to change, and in the future the geometry will be transferred by magnetic tape or by a network of computers."

Jan 1, 1986

By Griffiths J. B

From its mining lease at the northern end of Cohens Reef at Walhalla in the North Gippsland Mountains, the Long Tunnel Extended Gold Mining Company produced 13,695 kg of gold, which at 1980 prices represents a value significantly in excess of $200 million. In the period 1885 to 1908 the mine was one of Australia's principal reef gold producers, being top Victorian producer in six of these twenty-four years. Prior and subsequent occupants of the lease produced an additional 160 kg of gold. The Extended and the other mines on Cohens Reef whilst contributing importantly to the financial resource of Victoria, were the sole important support for the substantial town of Walhalla that had grown up around them. When the mines closed, Walhalla gradually reduced from a bustling developed town to the present attractive mountain village so favoured by tuurriSts. To allow the visitor to obtain a better ;ri.icrstanding of Walhalla's mining past, important parts of the Long Tunnel Extended Gold Mine workings and site are being

Jan 1, 1981

By Clifford S. Gibson

A year ago a paper (1) was presented at the Annual Western Meeting of the Institute regarding silicosis in Ontario mines. It described the whole problem as we see it and discussed the means of prevention. The work and aims of the Technical Silicosis Research Committee of the Ontario Mining Association, and of the Committee's field engineer, were fully described also and it is suggested that reference be made to this paper in order to have a better understanding of the observations which are presented now. These observations enlarge upon parts of the dust control measures already discussed and tell of general progress in the past year. They concern fifty properties, the majority of the operating mines, which vary in size from the hopeful prospect to established producers yielding 11,000 tons of ore daily. Most of these are gold mines; a few copper-nickel. The ores range from heavy sulphides to siliceous materials and they are mined by many methods from varying types of deposits. The majority of the latter are steeply dipping and all are found in Precambrian host-rocks. Up to the present, die greatest depth to which mining has penetrated is 6,400 feet.

Jan 1, 1939

By D. A. Paice

Direct current electrical systems are used in most coal mines primarily to power the main haulage trains and secondarily to feed other equipment and passageway lighting. Electrical power is supplied from rotary machines or static rectifier equipment and is distributed through the mine by open trolley wires and feeder cables. The rails of the haulageway are used as a current return path. This exposed power distribution system is very vulnerable to conditions which lead to undesired leakage currents and short circuits and, consequently, the possibility of fires or other hazards to personnel. Present techniques and equipment have been utilized in so far as practical to improve the safety of the dc electrical system; however, there still appears a need for further improvement. Because of this need, this program was sponsored by the Bureau of Mines to investigate two specific technical areas related to improvement of dc electrical system safety. One area included the determination of the characteristics of mine electrical systems and their protection requirements and the verification of the adequacy of available protective devices for mine service. Despite the widespread application of industrial protective equipment in mines, there was little detailed technical information available related specifically to the performance of this equipment in service. Our task was not only to develop useful information regarding mine system protection, but also to define and verify the adequacy of the protective devices available. The second area of investigation called for development of a practical technique for detecting low level electrical fault or leakage currents. Conventional protective devices

Jan 1, 2012

By Joseph Grumer

Theory pertaining to the exchangeability of fuel gases on appliances has been extended to exchanges of propane or butane with mixtures of these. In particular, new considerations were developed bearing on the hazard of an occasional emission of carbon monoxide and flashback and blowoff possibilities. The new considerations involve using current requirements for approval of liquefied petroleum gas appliances. These requirements were used to predict allowable tolerances in chemical composition of liquefied petroleum gases for existing appliances. In addition, changes in gasline pressure were computed which may be substituted in place of fuel exchanges during testing of appliances,

Jan 1, 1962

By Fathi Habashi

A new era in pressure hydrometallurgy is marked when the roasting - leaching - electrowinning process in the zinc industry was replaced by direct pressure leaching of zinc concentrate. Since then, the technology has received recognition as the technology of the future. Large autoclaves of unprecedented size have been manufactured and installed in a number of metallurgical plants for recovering copper and nickel from their concentrates or liberating gold from its refractory ores. An attempt to recover alumina from clay using pressure technology is underway. Autoclaves lined with acid resisting bricks or with titanium clad may weigh as much as 800 tonnes were transported successfully from the manufacturing workshop to the mine site over long distances.

Jan 1, 2014

By William Johnson

IT is now recognized that several important types of reactions in metallic systems proceed by the formation of nuclei and the growth of these nuclei. The process, of freezing is a simple example of this, as Tammann pointed out years ago.1Tammann held that the rate of freezing is determined by a rate of nucleation, expressed as the number of nuclei formed per unit volume of unfrozen liquid per second, and a rate of growth of these nuclei, expressed as the linear rate of radial growth in units of length per second. For isothermal freezing the conception is simple; for ordinary freezing, extending over a range of temperature, it is not as simple, for the values of the two constants must change with change in temperature. There is ample evidence that the postulated mechanism is correct even though a quantitative derivation of the rate of isothermal or of ordinary freezing in terms of the two constants has been lacking. In recent years other reactions have been found to proceed in a similar fashion. It has been well established, particularly by Bain,2-8 that the formation of pearlite from the eutectoid decomposition of the solid solu-tion austenite proceeds in such a way, and Polanyi and Schmid, Tammann and Crone, Parnop and Sachs, and others'-1 have shown that the process of recrystallization proceeds in a similar way. Isothermal reaction rates have been determined for eutectoid decom-position by a number of investigators. Bain's2-8 work on the formation of pearlite from austenite is especially valuable in this respect-the type of isothermal reaction curve obtained, as illustrated in Fig. 13, showed an initial slow rate, accelerating to an intermediate maximum rate which then decelerated to the completion of the reaction; similar curves have been obtained by Wever and his collaborators.' Other eutectoid decompositions show similar behavior: for example, the decomposition of the beta eutectoid in the copper-aluminum system, studied by Smith

Jan 1, 1939

By A. Bouvard, N. Hoteit, E. Boidy, F. Pellet

In the context of the construction of an Underground Research Laboratory devoted to the feasibility studies of radioactive waste deposits, it appears of the utmost importance to study the long-term behaviour of rock, over a long time period. In this paper, some results of tests performed on the argillite from the Meuse-Haute-Marne site test in Eastern France are presented. Then a numerical simulation of one of this test using the viscoplastic damaging constitutive law proposed by Lemaitre is presented. Finally, this law is used to simulate numerically the behaviour of the rock at the wall of a circular tunnel in order to determine the extension and the change along the time of the Excavated Damaged Zone (EDZ). Advantages and limitations of the model are discussed. Dans le cadre de la réalisation d’un laboratoire de recherche souterrain conçu pour étudier la faisabilité d’installations de stockage de déchets radioactifs, il apparaît fondamental de caractériser non seulement le comportement viscoplastique à très long terme des matériaux mais aussi les phénomènes d’endommagement consécutif à la redistribution de contraintes provoquées par l’excavation des cavités. On présente ici les résultats d’essais réalisés sur les argilites du site de Meuse/Haute-Marne et destinés à caractériser leur comportement visco-endommageable. Il est ensuite procédé à une application de la loi viscoplastique endommageable de Lemaitre pour simuler l'un de ces tests. Les apports et les limites d'un tel modèle sont mis en évidence par des simulations numériques du comportement de la roche au pourtour d'une galerie circulaire permettant de suivre l’évolution au cours du temps de la zone endommagée (EDZ) à la paroi . Im Rahmen des Baus eines unterirdischen Forschungslabors für die Untersuchung der Machbarkeit von Deponien für radioaktive Abfälle erweist es sich als äußerst wichtig, das langfristige Verhalten von Gestein über einen langen Zeitraum zu untersuchen. Im vorliegenden Artikel werden einige Ergebnisse von Untersuchungen vorgestellt, die mit Tonschiefer aus der Meuse-Haute-Marne in Frankreich durchgeführt wurden. Anschließend wird eine numerische Simulation der Untersuchungen unter Verwendung des von Lemaitre vorgeschlagenen viskoplastischen Verformungsgesetzes vorgestellt. Schließlich wird dieses Gesetz auf die numerische Simulation eines Kreistunnels angewandt, um die Ausdehnung und die zeitliche Entwicklung der Auflockerungszone (EDZ) zu bestimmen. Es werden die Vorteile und Grenzen des Modells diskutiert.

Jan 1, 2003

By W. E. Roscoe

The probability of making an exploration discovery in Canada can be calculated from Derry's (1970) data on exploration expenditures and number of discoveries over the last nineteen years. Considering an average exploration "try" to be $30,000, the probability of a discovery with one try has decreased tenfold from about 0.01 in 1951 to 0.001 in 1969. A plot of these probabilities can be extrapolated to the future, giving a 1969-71 three-year average probability of 0.00096 with 90 per cent confidence limits of 0.00042 and 0.00153. Using this probability, various calculations can be made, such as (1) the probability of making at least one discovery for any given exploration expenditure, (2) the probability of ultimate ruin or survival of the exploration investment process and (3) the expected value of an exploration investment. There is a critical minimum amount per discovery that must be re-invested in exploration, no matter how large the original investment is, for exploration to survive at all in the long run. Currently, this critical minimum is $31,200,000 with 90 per cent confidence limits of $19,600,000 and $71,400,000.

Jan 1, 1971

By Giovanni Franco Sepúlveda

Dado que los procesos de planificación minera en los depósitos a cielo abierto en Colombia se realizaron a través de herramientas deterministas que excluyen la evaluación de riesgos y las incertidumbres del negocio minero, se plantea modelos alternativos de planificación minera que optimizen las condiciones de competitividad y productividad a través del uso de los algoritmos genéticos y su aplicación a los procesos de planificación minera para explotaciones a cielo abierto. Es decir, se busca realizar una aproximación al planteamiento minero estocástico desde dichos algoritmos genéticos y así mejorar la cadena productiva del proceso minero.

Mar 1, 2014

By Cleciano Berlando Miranda de Oliveira

A Engenharia de manutenção em equipamentos siderúrgicos da CSN vem desenvolvendo habilidade e aplicando com ótimos resultados os recursos computacionais avançados com modelagem 3D e simulação numérica através de métodos de elementos finitos. Estes recursos estão se tornado um diferencial na dinâmica dos trabalhos de manutenção com foco em análises de falhas crônicas e respostas rápidas para a solução dos problemas. Caracterizando e estratificando as falhas é possível desenvolver melhorias e defendê-las com maior assertividade e credibilidade. O recurso computacional já está no mercado há tempos e a CSN está na vanguarda na formação de sua equipe própria com um nível avançado e grande potencial para otimização de resultados da engenharia de manutenção de equipamentos (GEM) da CSN-UPV. A missão principal é agregar valor aos ativos, com agilidade e confiabilidade na caracterização de oportunidades de melhorias dos projetos ou restabelecimento funcional. Trilhando um caminho contínuo no que tange a qualidade e assertividade nas soluções de problemas de equipamentos mecânicos, serão apresentados alguns casos de sucesso que estão em desenvolvimento e um projeto de melhoria nos rolos de entrada de um laminador de encruamento, localizado na saída da linha de recozimento contínuo para chapas número um (LRCC#1). Estes rolos apresentavam fraturas com frequências mensais gerando paradas de mais de 8 horas e, após os estudos e implantação do projeto em 2012, não houve mais registros de paradas por falhas nos rolos. O projeto foi padronizado e multiplicado para os demais rolos da LRCC#1 e outras linhas com projetos semelhantes.

Aug 17, 2017

By Kan Aketa

The Japanese iron and steel industry has been developed remarkably, supported by the increase of steel demand. In particular, progress in various technical aspects of the ironmaking process, including burden materials, equipment, and operation has greatly contributed to the increase in productivity and the reduction of the fuel rate in blast furnaces. With the recent rise in the price of petroleum, the conversion of the energy source from oil to coke has resulted in a temporary increase in the fuel rate of blast furnaces.

Jan 1, 1982

Process Study on Some Ag-Cu-Pb-Zn Polymetallic Ore in South China

Sep 13, 2010

By Barnabas Bryan

During the boom period of 1928 and 1929, several oil companies took advantage of high security prices to sell stocks, thereby securing money for the company very cheaply. Few if any of those companies realized that the money received was not at all cheap in view of the fact that it was for investment in fixed assets at inflated prices. Suppose a company borrowed twenty millions of dollars to expand its marketing facilities during the boom. It diluted its capital and acquired fixed property which could not earn its interest requirements during the following deflation and therefore consumed income from other company activities. The company also had to stand the deflation in the capital value of all the property it bought. Since the mistaken expansion during the boom accelerated the decline in net income during deflation, the financial position of the company was harmed in proportion to the amount of that expansion. Thus the company was unable to get money to buy fixed assets in the depression when all property is cheap. The same condition holds for the company that sold common stock for the purpose of developing potential production in a newly discovered oil field. Regardless of what the ultimate value of the new field may be, potential production does not increase the net income of the company. The difficulty of meeting the enlarged dividend requirements due to the increased number of shares outstanding impairs the financial position of the company during deflation in some relation to the probability of decreased dividends. This company also is not in a position to expand during the depression when properties and companies can be bought for a fraction of their real value. Expansion of fixed assets during boom times has been the ruin of many otherwise good companies. Some of those which most extensively bought property during the post-war boom have not yet recovered. A number of cases could be cited in sugar, leather, fertilizer and wool. This does not seem to be governed by the quality of the property bought, for examination shows the assets to have been of individual high quality in many cases. When recovery is long deferred it is likely to be true, as in sugar or textiles, that the industry has a large "potential" capacity for overproduction.

Jan 1, 1931

By D David

The majority of SAG and ball mill design methodologies are applied using a single design value for mill selection, such as the 80th percentile ball mill work index or SMC value. Inherent in the selection of this design value is a desire for the mill to accommodate unfavourable, but not absolute worst case, feed conditions. It has been observed in numerous “post-mortems” of unsuccessful designs and also in many optimisation studies, that the selection of the design value has been poor. Statistical analysis of testwork data sets shows that inherent variability in the data can, by itself, lead to design errors. Metallurgical testing is an attempt to measure the characteristics of millions of tonnes of ore using only a few kilograms of sample. In this paper some realistic but synthetic test work data sets are used to explore old and new methods of defining the design envelope and subsequently selecting a reliable point. The aim of the paper is to provide practitioners with tools that reveal the adequacy (or otherwise) of metallurgical test programs intended to support various levels of project design. It also provide guidance as to how it is possible to statistically justify a comparatively high design point in the absence of adequate test data.CITATION:David, D, 2015. Measuring and taking notice of orebody variability – an essential ingredient for reliable plant design, in Proceedings MetPlant 2015, pp 10–26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By R. G. Treuting

Germanium single crystals strained in tension at 600°C slip on the {Ill} plane and, macroscopically at least, in the <110> direction. Deformation is in homogeneous: various localized rotations are observed, as is a banding consistent with secondary slip banding. The structure after deformation is polygonized with a domain size of about 2x1O-3 cm. In relaxation tests, an incubation period prior to flow is observed, of duration inversely related to temperature and applied stress. Under continuous loading, there is a sharp first yield point. A critical resolved shear stress therefore must be cited with respect both to temperature and to rate of loading. At 600°C, when loading proceeds at 2900 psi per min, it is 1310 psi. The yield point phenomenon is suggestive of Cottrell&apos;s solute atom atmosphere theory and five points of qualitative agreement with this theory are found. PLASTICITY of germanium at elevated temperatures has been reported by Gallagher,&apos; who ascribed it to slip on {Ill) planes and described some associated effects. Preliminary experiments with single crystals of silicon and germanium loaded as simple beams confirmed {ill) as the slip plane of both materials.V his was demonstrated by the standard technique employing traces on two surfaces of known angle on a deformed crystal of known orientation.3 These experiments did not fix the slip direction, since more than one glide system operated. Uniaxial tensile straining is preferred for this purpose in order to restrict slip to one predominant system and to provide an unequivocal determination of the orientation change with respect to the stress axis. Experimental Method Specimens were diamond-sawed from germanium crystals containing about 5x10-5 wt pct Sb prepared by the zone-leveling process described by Pfann and Olsen;4 these specimens measured about 81/2 in. long, 0.20 in. wide, and were of various thicknesses from 0.035 to 0.060 in. Prior to testing, a specimen was coated over 1 in. or more of length at each end with Apiezon wax, chemically polished (in a solution of 15 ml HF, 25 ml HNO,, 15 ml CH3COOH, and 3 to 4 drops Br2), and dewaxed in warm xylene. A brief re-etching after scribing through a complete wax coating with vernier dividers provided gage marks at 0.200 in. intervals on the polished surface. A specimen with grips soft soldered to the ends was passed through the furnace tube and the grips pinned to the tensile machine in series with a stress gage. The Schopper testing machine is best described by reference to the illustration on p. 107 of Schmid and Boas5 and is operated with the pendulum arm locked, fixing the upper head. Load is applied through the screw-driven lower head, manually or by reduced speed motor. The furnace is 21/2 in. long surrounding a 4x7/16 in. ID quartz tube and was positioned about the specimen to permit free motion. The inert or reducing atmosphere required was sufficiently provided by a flow of helium introduced at the center of the furnace tube, with the tube ends loosely plugged with asbestos paper. Surface corrosion was slight. The stress gage employs a Be-Cu strip with SR-4 units incorporated in a simple bridge network with provision for balancing and calibrating. The bridge output on loading is fed through a Leeds and North-rup dc amplifier to a Speedomax 10 mv recorder, and calibration is obtained by dead loading. Experiments of two types have been conducted. Most have been in relaxation at constant elongation. One stress-strain curve has been taken with the machine continuously driven. Following extension of a specimen, Laue X-ray photographs were taken to obtain the orientation change between deformed and undeformed regions, recorded on a single film by translating the specimen in a plane normal to the beam between exposures. Sequences of such multiple exposures were made on some specimens to include the entire orientation range on one film. Slip Direction To obtain a maximum orientation change with a single slip system, crystals of very closely <110> axial orientation were used. The classic determination of slip direction rests on establishing that direc-

Jan 1, 1956

By A. W. Gauger

WITHOUT QUESTION the Commonwealth of Pennsylvania contains the most remarkable coal deposits of the whole world. Within its borders ,are to be found excellent coals ranging in rank from the high volatile bituminous of the western part of &apos;the state through the low volatile or semi-bituminous of central Pennsylvania to that aristocrat of solid fuels, anthracite, found in the East. . . . But while other states and even the Federa1 Government have recognized the needs of the coal industry, Pennsylvania has not. Though bituminous coal represents one of the most important industries in the state, far more important in annual productive wealth than agriculture, for example, hundreds, of thousands of dollars have been spent on agricultural research whereas little or nothing has been spent on coal investigation.

Jan 1, 1932

By J. L. Kohler

Component failures in the electrical control circuits of mining machines account for a large percentage of the total downtime of the machine, Once a failure has occurred it is always a tedious and usually a time-consuming task to locate the failed component. Moreover, the pressure to quickly locate the cause of a delay can lead to compromises in safety. Thus an onboard diagnostic system, essential for an automated machine, would be a very useful addition to existing machines. This report details U.S. Bureau of Mines development of a generic procedure for synthesizing diagnostic systems for electrical-control-circuit failures in mining machinery. A continuous mining machine is used as the testbed to illustrate the application of the developed methodology. Substantive differences among mining machine control circuits made it impossible to achieve a generic diagnostic system, but a generic approach for the synthesis of the diagnostic system was possible. As the research progressed, it became apparent that an algorithmic approach was better than an expert-system-based implementation. A prototype system was constructed and used to evaluate the diagnostic system. Prototype implementation issues are also examined.

Jan 1, 2010