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By M. S. Raseroka

An experimental rig has been constructed to produce chloride stress corrosion cracks in Type 304L stainless steel tube samples. The samples are to be used to test possible in situ repair methods in future work. The factor which influences the time to failure most strongly is the sample temperature; the distribution of cracks within the sample is affected by local temperature variations and by the position of the water line. Low-frequency oscillations in stress, caused by the on-off temperature controller, did not appear to influence cracking in these tests.

Jan 1, 2009

By Gordon King

The City of Atlanta Water Department required the construction of a two sludge tanks and a wet well at the existing Chattahoochee Water Treatment Plant. Western Summit won a design build contract to build the project and proceeded to evaluate the wet well size options, and construction procedures. The final design required the construction of a 1 million gallon tank. The proximity of the underground tank to adjacent roads and existing plant structures ruled out laying back the excavation. As a result a tied back sheet pile retaining wall was initially proposed.

Jan 1, 2003

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By Brad Simser

The Brunswick No. 12 Mine is a 10 000 tonne per day producer of lead-zinc-copper-silver ore that has been in operation since 1964. Mining of this multiple lens deposit is primarily by blasthole stoping techniques between 400m and 1200m below surface. The combination of a high overall extraction ratio and high horizontal stresses (twice the vertical) has elevated the induced stress regime to levels comparable to much deeper operations. Improved mine design, and a better understanding of how the rock mass responds to mining in high stress environments is essential to improve overall recoveries and maintain safety. Seismic monitoring has proven to be an essential tool at Brunswick, for both short-term safety of workers, and long-term strategic planning. Practical case studies illustrate how seismic data, particularly source parameter information, can be used to measure the rockmass response to mining and improve mining layouts in difficult regions. As the global trend continues towards mining in deeper, higher stress environments (e.g. South African Witswatersrand Basin, Sudbury Basin) and as local extraction and thus ground stresses continue to increase in existing deposits, seismic monitoring will play a critical role in mining safely and economically.

May 1, 2003

By J. D. Morgan

Demand for nonfuel minerals depends on the overall state of the economy, which steadily improved each quarter in 1984. New housing starts rose to 1.8 million units. Automakers turned out about 15% more cars (7.8 million) and 30% more trucks (3.1 million) than in 1983. Nevertheless, many domestic mineral operations experienced difficulties in 1984. This resulted from import competition greater use of newer engineered materials, emphasis on multi-unit housing and downsizing of motor vehicles. About 15% of our energy was imported. This in cluded $36 billion worth of crude oil and $22 billion in refined products This added significantly to the overall merchandise trade deficit of $12; billion. On the bright side for mining, coal production rose 14% to 810 Mt (890 mil lion st). Three-fourths o: the coal was burned to generate electricity and more than half of our electricity was derived from coal-burning plants. With the exception of a few large-bulk, low-value raw minerals, most minerals move relatively freely in world trade. The strong dollar encouraged imports and made exporting more difficult. Consequently, our nonfuel minerals trade deficit rose 60% to $19 billion, reflecting imports of $39 billion and exports of $20 billion. There were increased pressures from some major segments of the minerals industry for some form of import protection. But President Reagan said, "Our goal is a system of free and fair trade in goods, services, and capital. We will work toward this goal through both bilateral and multilateral trading agreements." The US minerals industry consists of domestic mines, concentrators, smelters, refineries, mineral manufacturing plants, and recyclers. It also includes many wholly- or partially-owned operations in many parts of the world, providing employment and income for US citizens and others as well. Compared with 1983, the value of US raw nonfuel mineral output rose 8%, to $23 billion. The $253 billion worth of goods processed from this crude mineral output was a 14% increase. Major Metals Raw steel production - a major indicator of both material use and mineral production-rose 10%, to 84 Mt (93 million st). This stimulated a 36% rise in domestic iron ore production, to 52 Mt (57 million st), about 98% pelletized. Iron ore imports rose 44%, to 14 Mt (15 million st). Despite the increase of steel production, output remained well below levels of just a few years ago. For example, 1984 production was still 23% less than in 1981. Raw steelmaking capacity remained steady at 122 Mt (135 million st). The industry continued to cite steel imports as a major reason for low domestic capacity. In December, pacts with seven leading steel exporting nations were announced. This is an effort to reduce import penetration to about 18.5% of the domestic market. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about 50% capacity. The US mined no manganese or chromium. Only a small quantity of ferronickel was produced from domestic laterite mining in Oregon. Molybdenum production, at 45 kt (49,500 st), rose threefold. Mine shipments of tungsten, another mineral tied to steel

Jan 5, 1985

Located in Timmins, Ontario the Porcupine Joint Venture, a pooling of assets between two existing operations (the Dome Operation of Placer Dome (CLA) and the Hoyle Pond Operation of Kinross Gold Corporation) came about on July 1st, 2002; Placer being the manager of the Joint Venture with 51% ownership and Kinross with 49%. The formation of the Joint Venture was the realization of the dream of many who could envision the benefits of the whole area being operated as one entity ? the combination of the majority of assets in the Porcupine Camp into one venture containing tremendous synergistic potential of manpower, infrastructure, land tenure and exploration development. The name Porcupine in the gold mining industry brings with it the legacy of world class gold mines; the Hollinger, McIntyre and Dome with a proud tradition of excellence. The name Porcupine brings with it the legacy of over twenty individual mining companies in operation at any one time, producing over 65 million ounces of gold.

May 1, 2003

The presence of undetonated explosives in a rock face after firing constitutes a hazard which can result in a fatal or serious accident if undetected before drilling commences.Most accidents caused by drilling into explosives are the result of failure to examine the working face properly and lack of care in subsequent drilling operations; it is not always realized that explosive may be left in the butts of holes or may be driven into cracks or crevices in the rock.Obviously the best means of preventing accidents of this nature is to adopt methods of drilling, charging and firing which will reduce the hazard to a minimum.There are three ways in which undetonated explosives may be left in the rock face, namely:1. Misfires.2. Cut-off shots.3. Incomplete detonation or failure of the charge to propagate throughout.MisfiresNo attempt will be made in this paper to deal fully with the question of the prevention of misfires, as apart from the fact that most of the preventive methods are well known, it is believed that if the miner receives his explosives and means of initiation in good order, and proper care is taken in their use, the failure of a charge to fire will be a rare occurrence. The provision of central fuse capping stations on mines has gone a long way towards the elimination of misfires caused by the mishandling of safety fuse anddetonators.

Jan 1, 1956

By J. B. Elizondo

This paper, which describes mining methods and practices at the Piokee mining unit and the Piokee expertmental mining project of The Eagle-Picher Co. in northeast Oklahoma, is one of a series being prepared by the Federal Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. The Piokee unit, comprising the Piokee, Rowe, Lucky Syndicate, and parts of the Netta White and Otis White leases, is in the SW1/4, W1/2NW1/4SE1/4, and W1/2SW1/4SE1/4 sec. 17, T. 29 N., R. 23 E., Ottawa County, Okla. (figs. 1 and 2), The 200-acre tract is adjacent to the town of Picher and near the heart of the Picher field of the Tri-State zinc-lead mining district.

Jan 1, 1959

By Jennifer Ward

The primary objective of this paper is to establish how a low cost, high definition (HD) camera can allow for easy sustainable recordings of blasting operations. The subsequent analysis of each video can be utilized to monitor what type of performance was achieved and aids in improving blasting performance.

Jan 1, 2015

Interest in those physical properties of minerals which might be used to good effect in prospecting is not new. Early in the nineteenth century attempts were made in th'e Cornish mines to measure the natural electric potentials set up by chemical changes proceeding in the lodes. The distortion of the earth's magnetic field by bodies of strongly magnetic iron ore received early recognition in Sweden. Treasure-finders, working on the principle of electrical induction, appear to have been invented about eighty years ago, though were probably not then applied to mineral exploration. By the end of the nineteenth century Eotvos, a Hungarian physicist, had constructed a highly sensitive type of torsion balance capable of measuring the minute distortions in the earth's field of gravitation resulting from variations in the density of the materials composing the crust. During the first decade of this century he demonstrated its value in tracing rock-salt deposits in virtue of their low density compared with the surrounding rocks. Geophysical prospecting began to be recognised as having a very definite value and its development gathered momentum. Its great expansion took place after the 1914-18 war, when its value in oil exploration was amply demonstrated, and this expansion has continued to the present time and shows no signs of abating.Divisions of Applied Geophysics.The four main divisions of applied geophysics are electrical, magnetic gravitational and seismic. With the importance of ores of radio-active metals, one might add to these a radio-active division. The first two are more important to the field of mining, but techniques based on gravitational attraction have their uses in particular cases. Seismic methods are not generally suited to the exploration of metallic ores, but have proved of enormous value in the search for petroleum. With vast quantities of oil as the prize, more money has been lavished on the deve10pment and practice of these methods than on all the others put together.Geophysical Prospecting Methods.Geophysical prospecting methods may be used to detect a mineral deposit directly in virtue of differences in the intensity of some physical attribute common to it and the enclosing country rock. Examples of this are the detection of rock-salt by gravity measurements, or of iron ore by magnetic methods. Of much wider application, however, is the indireot approach in which the aim is to determine, by geophysical means, the geological structures controlling the disposition of mineral deposits. These structures may be partly known from geological work, in which case geophysical methods are useful adjuncts. Where, because of an 'unbroken cover of overburden, no useful geological information presents itself, scout drilling or geophysical prospecting are the only alternatives. Overburden is here intended to mean any covering material not, involved in the structures controlling the mineral deposits. Prospecting for petroleum amounts to the detecting of favourable reservoir structures, and as the chief types of such are the same the world over...

Jan 1, 1950

By M. Moseki

Paper written on project work carried out in partial fulfilment of B.Sc. (Eng.) (Metallurgy of Materials) degree This paper presents the research into melting of scrap for job creation purposes in rural areas. The research was done on behalf of Mine Recycling Services (MRS), the company that will implement the project. The project involves the research into available cost effective and easy to operate technology. The paper covers the experimental and theoretical work that was conducted. The results were used to determine the best equipment and method for melting and casting brass scrap.

Jan 1, 2002

By Chris Larsen, Ian Orford, Mike Cooper

"An autogenous grinding circuit was commissioned at the Brunswick concentrator in October 1998. The autogenous grinding circuit replaced existing surface crushing plants, fine ore storage, rod and primary ball mills. The 8.54m diameter x 4.27m long (EGL) AN1 mill is driven by a bidirectional variable speed 6.3MW ABB wound rotor motor with Slip Energy Recovery (SER) drive. The AG mill was subsequently converted to SAG operation in May 1999 for a number of reasons. The mill is operated in closed circuit with horizontally inclined 660mm diameter cyclones to produce a circuit product P80 of 85 microns. Extensive test work and JKSimMet design modeling resulted in a production circuit operating closely within design expectations.The circuit is highly instrumented and controlled via a hybrid Programmable Logic Controller (PLC-5) and Fisher PROVOX Distributed Control System (DCS) that is in communication with the property information highway. An expert control system (Gensym G2) is used for control of the SAG mill load.Engineering and construction were completed in 28 months from the time of management approval for the project. The Brunswick AG/SAG mill circuit was commissioned on schedule at the $M 23.5 forecast budget."

Jan 1, 2001

By A. Visnapuu

Excessive noise and high vibration are inherently associated with equipment used in the mining, extraction, and processing of mineral resources. High vibration degrades structural components, often leading to catastrophic failure and loss of productivity, and excessive noise can result in permanent hearing loss. In order to foster efficient utilization of the Nation's mineral resources and minimize occupational hazards associated with mineral processing, the Bureau of Mines investigated the relationship between the microstructures of carbon and alloy steels and cast irons and their damping capacities (ability to absorb vibration). Researchers measured damping capacity and other properties and investigated the effects of carburizing, spheroidizing, and annealing. The investigators found that in carbon and alloy steels, rounded colonies of fine-grained pearlite in a ferrite matrix correlate well with low damping capacity. Steel microstructures that exhibit sharp-faceted pearlite in ferrite matrix and partially or fully spheroidized cementite in ferrite show considerably higher damping. In cast irons, the lowest damping capacity is associated with nodular graphite microstructure, and the specific damping capacity (SDC) increases as the graphite micro-structure progresses from nodular to compacted to flake. Predominant ferrite in cast irons is also associated with good damping. SDC data are presented for selected carbon and alloy steels and cast irons.

Jan 1, 1987

By Henrique Silva Furtado, Flaviani Marculano Marchesi, Silas Gambarine Soares, Elton Volkers do Espírito Santo, Felipe Fardin Grillo, Heitor Cristo Clem de Oliveira

Devido ao aumento da restrição do teor de enxofre nos aços torna-se necessário investigar a eficiência do processo de dessulfuração de ferro gusa. Portanto, o objetivo deste trabalho é empregar diferentes matérias-primas e fundentes como cal calcítica, sodalita, pré-cal, mistura padrão, fluorita, escória de KR, borra de alumínio e B2O3, a fim de encontrar a composição com maior eficiência de dessulfuração, relacionando-a ao fator de dessulfuração, obtido pela termodinâmica computacional. Os testes foram realizados a 1350°C, em uma atmosfera inerte com agitação constante. Os resultados mostraram que a mistura com maior eficiência foi aquela com 69% de cal, 5% de sodalita, 15% de pré-cal, 6% de escória KR e 5% de B2O3.

Oct 1, 2019

This Department handles all ores prior to blast-furnacing, the object of the operations being to mix the lead-bearing material with fiuxes, eliminate sulphur from the mixture, and produce a homogeneous sintered product which is chemically and physically suitable for treatment in the blast furnaces.During the financial year ended the 30th June, 1937, the tonnage of charge treated was 458,960 tons, containing some 183,470 tons of lead and 8,504,000 oz. of silver.The quantities of the principal components of the charge treated were as follow:-

Jan 1, 1937

By A. Ochieng

Solids suspension influences the quality of mixing and energy requirement in a solid-liquid system, both of which determine the efficiency of industrial processes such as nickel precipitation. Nickel solids concentration distribution in a stirred tank was investigated using computational fluid dynamics (CFD) and experimental methods. The concentration distribution of the nickel solids was compared with that of sand and glass. The laser Doppler velocimetry (LDV) method was used to measure the velocity field for the liquid-only system and an optical technique was employed to determine the axial solids concentration distribution. Regions of in homogeneity in the tank were identified. It was found that, for a given solids loading, the solids concentration distribution depended on both particle size and particle size distribution. High solids loadings were investigated and a difference in the concentration distribution pattern was obtained with nickel, flint glass and sand particles. The CFD simulation results highlighted problems that could be associated with some conventional experimental methods of determining solids concentration distribution in a stirred tank. Keywords: nickel; CFD; simulation; mixing; solids suspension.

Jan 1, 2010

By A. E. Lewis

Particle morphology is a term that is used to describe the overall external shape and appearance of particulate solids. From the physical point of view, a precipitated solid is characterized primarily by the size and morphology of the particles (Sohnel andGarside, 1992). If the morphology of the crystal structures is to be related to the processing conditions, then the morphologies need to be quantified in some way. This can be achieved by using surface area measurements as well as fractal dimensions. The key idea is that rugged and indeterminate systems can be described by using a fractional number that describes the ruggedness of the system (Kaye, 1989). In other words, when the complexity of a structure, such as an agglomerate, increases with increasing magnification, it is useful to employ fractal dimensions to describe the structure. Fractal geometry proposes that, instead of attempting to measure the length of an irregular boundary, the rate at which the length of the boundary approaches infinity with increasing resolution should be calculated. Cross-sectional profiles of rugged particles can thus be quantified using the fractal dimension, and a measurement of the ruggedness of the morphology obtained. One of the additional uses of measuring the fractal dimension is that the measured value can be related to the physical properties and formation characteristics of the particle (Kaye and Trottier,1995). The morphology of nickel crystals was quantified with fractal dimension calculations of particle cross-sections. Particle cross-sections were obtained by mounting the particles in resin and polishing back. These were then photographed using Scanning Electron Microscopy and the resulting profiles analysed using the structured walk technique.

Jan 1, 2001

By André Luiz Vasconcellos da Costa e Silva

O sistema ferro-oxigênio alumino tem sido investigado há muitos anos em função de sua importância para a indústria do aço. Uma grande fração de todo o aço plano produzido é de aço de baixo carbono acalmado ao alumínio, não apenas pelo baixo conteúdo de oxigênio residual em solução que pode ser obtido mas, também, pela importância do alumínio residual na formação de AlN, ferramenta importante no controle de estrutura e textura obtidas. O sistema Fe-O é relativamente bem compreendido e quantificado, da mesma forma que o sistema Fe-Al. Entretanto, há discrepâncias significativas na quantificação do comportamento do sistema Fe-Al-O havendo, ainda, bastante controvérsia com respeito a equilíbrios importantes. Assim, o objetivo deste trabalho é (a) realizar uma revisão crítica dos experimentos e avaliações termodinâmicas principalmente do equilíbrio Al-Fe-O–Al2O3 (b) avaliar os métodos atualmente usados para descrever este equilíbrio e (c) apresentar recomendações sobre os dados, com base em sua confiabilidade e consistência.

Aug 16, 2017

By Esteban Bravo

El presente señala la utilidad del último software y equipos desarrollados como herramientas que permiten analizar, monitorear y reparar los problemas que se presenten en el funcionamiento de motores diesel, además de disminuir los costos para su mantenimiento.

Aug 25, 2002

By R. Pothina

The objective of this research was to develop a mathematical model for gyratory crushers to help in the prediction of energy consumption and to analyze dominant parameters that affect this energy consumption. The development of a gyratory crusher model was achieved in the following three main stages: mathematical representation and coding of the crushing process; building an amperage constant model to derive an energy-scaling formula; and modifying the amperage constant model to represent a full-scale model. Due to their significant influence on feed-size distributions, two blasting parameters, i.e., burden and spacing, were considered. The crusher parameters that affect energy consumption were also identified. A case study of an operating dolomite mine was performed. The results indicated that by changing the burden, spacing and crusher closed-side setting, the overall (blasting and crushing) costs could be reduced by 4.7% to 7.9% annually. It can also be concluded that burden and spacing values have a linear positive relationship with the crusher energy consumption, while closed-side setting values have an inverse linear relationship with the energy consumption.

Jan 1, 2007