Search Documents

By R. L. Ziegfeld

It has often seemed to me that people are too prone to turn to new and untried materials in an effort to solve their problems, without giving sufficient consideration to the old stand-bys, except as a last resort, It?s a little like middle-aged men who are swept off their feet by the fresh beauty of a young girl without first considering the many advantages that a more mature woman has to offer. Maybe it?s because, like the older woman, the older materials have to make a determined effort to keep themselves looking young and attractive. T at?s just about the situation with which the lead industry is laced. We have to make a determined effort to keep lead looking young and attractive to industry. However, there is one difference and it is important, Lead can not only be kept looking young, but it can, in fact, actually be kept young, This results from two things. First, industry and technology are constantly changing. For example, we have known for years that the density of lead makes it ideal to stop gamma rays, but it is only recently that atomic fission as a source of gamma radiation has become an important tool of industry, That makes old knowledge about lead useful in developing a new market for it.

Jan 1, 1958

By C. M. Myrick

(Cleveland Meeting, October, 1912) THE following notes are submitted in the belief that they may interest some of the many owners of small water-power plants, so generally used in mining-work throughout the West. A small and somewhat primitive quartz-mill was taken over by a leasing company, and a 10-stamp battery was installed. Originally, power had been furnished by a Pelton wheel ; but, since the supply of water depended on the rate at which snow was melting on the mountains, a steam-plant had been added to help out during cold spells. This auxiliary plant was antiquated and expensive to operate, and, soon after starting up the remodeled mill, it broke down completely; so that it became necessary to get all the power possible out of the Pelton wheel,. with its ever-varying water-supply. The pipe-line, about a quarter of a mile long, was made up. of assorted sizes, from 7 to 11 in. in diameter; and, since it was buried deep under snow, there were no data from which to calculate the theoretical size of the nozzle. The stream being at this time at a low stage, it was important to make the most efficient use of the available water. This was done by using a nozzle large enough to pass the whole supply-taking care, however, to limit the size so as not to lower the water-level in the tank at the head of the pipe-line. As the weather became warmer, the nozzles were gradually enlarged to meet the increasing volume of water; but a point was finally reached where further enlargement only gave decreased power. Evidently the loss from friction had more than balanced the gain from the increased flow through the pipe. However, the area of nozzle that developed the, maximum power from the pipe-line had been found. This was used; and the surplus water was allowed to run to waste at the head of the line.

Oct 1, 1912

By W. E. Halle, G. J. S. Govett

"The Institute of Applied Geology, Manila, Philippines, is jointly sponsored by the University of the Philippines, the Philippines Bureau of Mines and the United Nations Development Programme (Special Fund). It provides, in its fourth year of operation, an interesting example of international cooperation in mineral development. Objectives include: (1) the training of mining engineers in modern techniques of mineral exploration; (2) assisting government and industry in discovering new ore deposits; and (3) providing the basis for the establishment of an economically oriented graduate school of geology at the University, the first of its kind in the country. Training of engineers requires roughly one full year, which is divided between academic study and actual field practice. Lecture and laboratory instruction include courses at university level designed specifically to up-grade those aspects of the geological sciences that are required by mining engineers now qualifying as mineral exploration engineers-economic geology, applied geochemistry, geo-physical exploration, petrology and structural geology. The field training involves direct participation in actual mineral exploration projects arranged with the co-operation of the Bureau of Mines and private interests engaged in mineral development and production. The system works well in practice, and the Institute staff and trainees were responsible for outlining new evidence of economic mineralization. It is also apparent from the application of the exploration methods available to the project -geological mapping, air photo interpretation, magnetic, electric, electromagnetic, self potential and gravity surveying as well as geochemical prospecting -that, under the humid, tropical, mountainous conditions in which the practical program was conducted, air-supported geochemical prospecting with attendant reconnaissance geological mapping affords the most economical and effective approach to mineral exploration for at least some of the deposits characteristic of the region."

Jan 1, 1968

By P. W. Bridgman

DURING the war, the Navy undertook the construction, under my direction, of an experimental gun embodying features designed to lessen the cost and time of production. These experiments were initiated after representations as to their, desirability had been offered by myself, by the Naval Consulting Board, and by the National Research Council. The first drawings were made in June, 1917, and the experiment was completed in November, 1918. For the sake of clearness it will pay to recapitulate briefly the fundamental idea of gun construction. It is well known that if a hollow cylinder is subjected to internal fluid pressure, the maximum stress occurs in the inside layers, the outer parts carrying much less than their due share of the stress. This inequality of stress is more pronounced the thicker the walls of the cylinder. If such a cylinder is pushed to the elastic limit, failure in elasticity will take place long before the outer layers have reached the limit of their capacity. Economical use of the material would demand, however, that all parts of the cylinder reach the limits of their capacity simultaneously. This may be brought about, at least in cylinders of not too great thickness, by producing in. the inner layers an initial compression, and in the outer layers an initial tension. The effect of internal pressure is at, first to relieve the compression of the inside layers, while increasing the tension of the outside layers. If the initial stresses are properly distributed, all parts of the cylinder will reach their elastic limits simultaneously, thus giving a cylinder of maximum strength for its weight. In gun construction as hitherto practiced, this initial distribution of stress is produced either by winding the inner tube with wire, a common English practice, or by shrinking hoops over the inner tube, which has been the standard American practice. Either process is long and expensive, particularly with the larger guns, 12- or 14-in., which require

Jan 2, 1920

By G. Shaw

IN recent years, most of the reconnaissance work of the Geological Survey of Canada has been mapped on a scale of 1 inch to 4 miles. Topographic base maps, commonly made from aerial photographs, were available to the geologist for such work. The advent of war curtailed aerial photography for civilian purposes, and by 1941 all areas already photographed had been geologically mapped. Nevertheless, the need for geological maps to assist post-war prospecting was so apparent, and the country to be covered is so vast, that some new method of rapid mapping had to be devised. It was felt that the need would be met if geological maps could be produced at a scale of 1 inch to 8 miles, provided they were sufficiently accurate in topographic detail to serve as guides to travel. Though in such maps there would be considerable sacrifice of geological detail, they would serve to outline, at least approximately, the major geological units, some of which might prove of sufficient interest to warrant later detailed study. It seemed that such mapping would be particularly useful in the northern regions of Canada which the work of early explorers has indicated are underlain largely by granitic rocks. These, so far as is known, are barren of mineral deposits, but within them are known to be areas or bands of 'greenstones' of the type that, in some localities, have been found to contain valuable orebodies. The problem, then, was to devise a method of mapping, particularly of such greenstone bands, that would make it possible to cover a relatively large area-say 30,000 square miles-in one season and at a cost below that of 4-mile mapping, with, of course, some sacrifice of accuracy. The problem seemed to be threefold: (a) to observe as much of the bed-rock as possible; (b) to produce a topographical map of as much of the area as possible, with particular reference to portions of geological interest; and (c) to cover as large an area as possible in a limited time, which meant faster modes of travel than have hitherto been used. The obvious answer to all three phases of the problem was the use of aircraft. If rock types could be broadly differentiated from the air, reconnaissance traverses by air would supply the answer to the first part of the problem. For topography, air photographs taken on reconnaissance flights appeared to be the answer. For the third phase of the problem, the use of aircraft was ideal.

Jan 1, 1943

By V. K. Gupta

Several approaches to the estimation of the size discrete breakage rate and distribution parameters (kj and bi,j ) of the batch grinding kinetic model are available in the literature. Analysis of a large amount of data available in the literature and our own data on several pure minerals and complex ores has shown that it is not always possible to obtain correct estimates of the two sets of parameters using known approaches as several widely different combinations of k and b parameters can sometimes simulate the batch grinding data reasonably accurately. It has been found that there are two main reasons: (i) all size classes are not well represented in the data and (ii) functional forms used for estimation of the two sets of parameters are sometimes chosen somewhat arbitrarily (especially in the case of complex ores), though they are actually uniquely related through size continuous breakage rate and distribution functions. A suitable experimental methodology has been described and demonstrated using some synthetic data and actual experimental data. A mill function approach, which does not require making any assumptions about the functional forms for k and b parameters, is also described and demonstrated. This approach is promising, but requires further development.

Sep 1, 2012

By James E. Simpson, Suresh V. Garimella, III de Groh

"An experimental and numerical study of the horizontal Bridgman growth of pure succinonitrile (SCN) and of a succinonitrile-1.0 mol. % acetone alloy (SCN-1.0 mol. % ACE) has been performed. Experiments at growth rates of 0, 2 and 40 µmis were investigated. The solid/liquid interface was stable (non-dendritic and non-cellular); however, it was not flat. Rather, it was significantly distorted by the influence of convection in the melt and, for the growth cases, by the moving temperature boundary conditions along the ampoule. For the alloy, the interface was determined to be unstable at growth rates greater than 2.8 µmis, but stable for the no-growth and 2 µmis growth cases. When compared to the pure SCN interface, the alloy interface forms closer to the cold zone,· indicating that the melting temperature has been suppressed by the addition of the alloying element. Two-dimensional computer simulations were performed for the no-growth case for both the pure and alloy materials. These simulations indicate that a primary longitudinal convective cell is formed in the melt. The maximum magnitude of velocity was calculated to be 1.515 mmls for pure SCN and 1. 724 mm/s for the alloy. The interface shape predicted by the computer simulation agrees well with the experimentally determined shape for the pure SCN case. In ongoing work, numerical simulations of the process during growth conditions are being performed.IntroductionIncreasingly, advanced materials used in the aerospace, automotive, optics and electronics fields require low levels of defects and high levels of solute uniformity. Directional solidification by the Bridgman process is widely used for synthesis of these high-quality materials. During Bridgman crystal growth, heat and mass transfer by both thermal and solutal gradient-driven convection and diffusion influence the shape of the solid/liquid interface and dopant segregation levels, and hence, directly determine the final crystal quality. Key process parameters include the applied furnace temperature distribution and rate of translation, ampoule properties and furnace orientation."

Jan 1, 1999

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By Brown A

An experimental evaluation of a selective agglomeration process in which an agglomerated coal rich phase was produced as a result of mixing light oil to various raw coal slurries is described. The beneficiation achieved by this method is compared to that obtained bv conventional froth flotation. The results suggest' that oil agglomeration is a more selective process than froth flotation and is less sensitive to variations in feed pulp density. Selective agglomeration has the additional advantage of producing a low moisture content product. The effect of replacing flotation filter cake with an equivalent amount of selectively agglomerated product in coke-making was studied with the aid of a pilot-scale coke oven. The results suggest that the principal effect of such a measure is to increase the bulk density of the charge.

Jan 1, 1977

By Harold J. Schock

This paper describes an experimental method for the monitoring of diesel-generated exhaust gas pollutants in a dead-ended drift for the purpose of assessing the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 105 ft. (32.0 mf long and slightly downsloping, with an average height and width of 8 ft. (2.4 m) and 28 ft. (8.5 m1 , respectively. The data were gathered for assessing these ventilation methods and for gathering data to support a computer model of the dispersion and mixing processes. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generated pollutants. Induction ventilation appeared to be the least effective of the three methods examined. A comparison was also made between personal monitoring and area monitoring. Results of this analysis showed that in regions of high concentration gradients, it was not possible to get good agreement between point sampling and personal monitoring. In well-mixed areas, good agreement between the two methods of monitoring was obtained.

Jan 1, 1980

By S. -H. Chang, C. -I. Lee, Y. -K. Lee

Based on results from triaxial compressive tests, an experimental damage model to simulate post-peak behaviours as well as nonlinear behaviours before peak strength was developed. In order to consider pre-peak behaviours, variations of elastic constants at each damage level were regressed by functions of confining pressure. In addition, post-peak behaviours were simulated successfully by using Hoek-Brown constants. As results, the experimental model could predict nonlinear behaviours, peak strengths and stiffness changes observed in experiments. Basé sur des résultats des essais compressifs à trois axes, un modèle expérimental de dommages pour simuler des comportements de poteau-crête aussi bien que des comportements non-linéaires avant la force maximale a été développé. Afin de considérer des comportements de pré-crête, des variations des constantes élastiques à chaque niveau de dommages ont été régressées par des fonctions de pression d'emprisonnement. En outre, des comportements de poteau-crête ont été simulés avec succès en employant des constantes de Hoek-Brunes. Comme résultat, le modèle expérimental a pu prévoir des comportements non-linéaires, des forces maximales et des changements de riidité observés dans les expériences. Auf Basis der Ergebnisse des dreiaxialen Drucktests wurde das experimentelle Schadensmodell, das sowohl das nicht-lineare Verhalten vor der maximalen Stärke als auch das Verhalten nach der maximalen Stärke simulieren kann, entwickelt. Um das Verhalten vor der maximalen Stärke zu berücksichtigen, wurden die Veränderungen der elastischen Konstante bei dem jeweiligen Schadensniveau durch die Funktionen des begrenzten Drucks zurückgegangen. Außerdem wurde das Verhalten nach der maximalen Stärke unter Benutzung von Hoek-Brown Konstanten erfolgreich simuliert. Schließlich konnte das experimentelle Modell das nicht-lineare Verhalten, die maximale Stärke und die Veränderungen bezüglich der Steifigkeit während der Experimente voraussehen.

Jan 1, 2003

From March to May of 1963, the Bureau of Mineral Resources carried out an experimental aeromagnetic survey at Cobar, New South Wales, to field test a proton-precession magnetometer installation in the Cessna aircraft VH-GEO. The Cobar area was chosen as considerable information was already held on the Earth's magnetic field there, which was known to provide a range of anomalous areas that are not excessively disturbed.A procedure for survey flying and methods for processing data were developed during the survey. Contour maps of the aeromagnetic results were produced in the field. The experimental survey was successful in outlining magnetic anomalies in detail.INTRODUCTIONSince 1951 the Bureau of Mineral Resources, Geology and Geophysics (B.M.R.) has carried out an airborne magnetometer exploration programme with DC.3 aircraft carrying fluxgate magnetometer equipment. Recently a proton-precession magnetometer was developed by the Design and Development Group of the B.M.R. for observatory use. One unit modified for airborne use was installed in the Cessna light aircraft, VH-GEO. The Cessna was modified structurally to take the magnetometer, associated bird, and winch gear.The proton-precession magnetometer has many good features.1. It utilises the transistor and associated solid-state devices in its electronics, and hence is light and small.This is the basic feature allowing its installation in a light aircraft. The transistor circuits have a high reliability factor and owing to the card sub-unit...

Jan 1, 1964

By M. K. Mishra, U. M. R. Karanam

Relative to slender pillars, larger size pillars exhibit improved strata control. Fly ash, though traditionally treated as a waste product, is emerging as an alternate engineering material. This paper deals with the development of a strong fly ash composite material with additives. The geotechnical properties of this fly ash composite were determined and used to trap model core pillars, which resemble squat pillars. The trapped samples were tested under uni-axial loading in the laboratory and the results showed higher load-bearing capacity of the model core pillars. The reinforced fly ash composites provide lateral confinement and exhibit improved post- failure behaviour of the model cores.

Jan 1, 2008

By Mark Kruzynski, Srinivas Garimella, James T. Wiswall

"A flue gas recirculation (FGR) system for a combustion fired aluminum melting furnace is experimentally investigated. The FGR system flows combustion air in a turbulent jet within the flue gas stream, and the turbulent jet flow is collected in a tube at a distance from the jet exit. Entrainment of the flue gases as well as heat transfer between the flue gases and the jet occurs over the length of the exposed jet. Heat transfer between the flue gases and the jet, and the amount of flue gas entrained into the jet (derived from temperature, flow rate and oxygen fraction measurements) were measured as a function of nozzle exit velocity and the distance between the nozzle exit and collection tube. In addition to flue gas entrainment, a fuel savings of up to 7%, due to heat transfer over the length of the jet, was projected from the measurements obtained.IntroductionFlue gas recirculation can be applied to aluminum melting furnaces to control combustion temperature. When coupled with a device to improve furnace efficiency by recovering heat from the furnace exhaust, flue gas recirculation provides a control technique that is integral to achieving the goals of reducing fuel consumption, increasing product yield, increasing the longevity of infrastructure, and reducing pollutant emissions. In particular, combustion temperature control can help reduce reactivity of the products of combustion with the molten metal surface and furnace refractory materials. Combustion temperature control can also help improve the life of heat exchangers used to recover energy lost to the environment in the flue gases, and reduce NOx formation in the combustion process. Flue gas recirculation can also dilute oxygen used in oxy-fuel combustion to reduce reactivity.Flue gas recirculation has been used since the 1970s to control flame temperatures in the automotive industry [1-3] and has successfully reduced NOx emissions. Many different flue gas recirculation approaches for high temperature melting such as melting aluminum and glass have been patented since the 1980s [4-12]. There has also been academic interest to determine the fundamental performance characteristics of flue gas recirculation in high temperature furnaces and in combustion [13-15]."

Jan 1, 2014

By Susanna A. C. Stadler, Chris Aldrich, Jacques J. Eksteen

Slag foaming occurs in several pyrometallurgical processes. These processes include steelmaking in basic oxygen steelmaking furnaces and electric arc furnaces as well as various non-ferrous operations like sulphide smelting/converting and base metal slag cleaning. Although slag foaming in steelmaking processes has been extensively researched, little attention has been given to slag foaming in non-ferrous operations. Slag foaming phenomena are complex because often the system consists of three or more phases. With this in mind, factors previously identified as influencing slag foaming were investigated. These include the slag basicity, physical properties of the slag, namely viscosity, surface tension and density, the formation of particles due to undercooling of the slag and the FexO concentration in the slag. The effect of increasing FexO concentration was found to decrease the foam index due to lower viscosities, but higher surface tension depression appears to have led to increased foam index values at high FexO concentrations. The foaming index decreases with increasing basicity, until precipitation of solids occurs. After this point, the foaming index was found to increase with increasing basicity due to increased solids precipitation. In general, increasing amounts of slag-wettable solids led to higher foam indices, but the precise nature of the effect on slag foaming was dependant on the nature of the solid precipitate.

Jan 1, 2003

By S. Z. Shafaei

An experimental investigation has been carried out using a laboratory scale Denver flotation cell. For evaluation of cokeable coal of Alborze Sharghi coal washing plant, the full factorial method was used to statistically design and analyse the experiments. The 2 factorial interaction model were developed for combustible recovery and ash content as response and diesel dosage, conditioning time, feed percent solids and rotor speed as factors. Model validation and residual analysis were con-ducted and results indicated that the fitness, predictability power and residual distributions of models were good. The effect of parameters and interactions were examined and it has been demonstrated that rotor speed, solid percent and interaction between diesel dosage and solid percent were more important terms of all responses. A product with approximately 78% combustible recovery and 10% ash content was obtained at 4000gr/ton diesel fuel oil (high level), 30 sec conditioning time (low level), feed percent solids of 15% (low level) and 800 rpm rotor speed in appropriate condition.

Jan 1, 2014

By Mohammed Al Maadheedi

This paper explores the capacity effects of a square steel plate welded at the ground surface on a driven open-ended steel pile (i.e. the plate would touch the ground surface after the pile achieves the required penetration). A series of strain-controlled, 1-g laboratory tests were undertaken on piles with and without a square steel plate attached. The piles were driven in dry, loosely packed, uniform sand. Two plates were used, one with a breadth equal to two times the diameter of the pile (2D) and the other with a breadth equal to three times the diameter of the piles (3D). A 20% increase in capacity was recorded for the 2D plate, and a 110% increase in capacity was recorded for the 3D plate when compared to the pile without an attached steel plate. The back-analysis of the results allowed the derivation of a new expression to calculate the capacity of bearing plates, which accounted for the effects of sands compaction and dilation. By extrapolating the findings of these tests to a hypothetical scenario, a model design problem was described where the length of a pile can be reduced by 20% to 60% (depending on the load) by using a plate attached to the pile. The results of this study can help designers to minimise penetration depth; thus, achieving a more economical and sustainable design.

By Nick Hytiris, Mohammed Al Maadheedi, Slobodan B. Mickovski

This paper explores the capacity effects of a square steel plate welded at the ground surface on a driven open-ended steel pile (i.e. the plate would touch the ground surface after the pile achieves the required penetration). A series of strain-controlled, 1-g laboratory tests were undertaken on piles with and without a square steel plate attached. The piles were driven in dry, loosely packed, uniform sand. Two plates were used, one with a breadth equal to two times the diameter of the pile (2D) and the other with a breadth equal to three times the diameter of the piles (3D). A 20% increase in capacity was recorded for the 2D plate, and a 110% increase in capacity was recorded for the 3D plate when compared to the pile without an attached steel plate. The back-analysis of the results allowed the derivation of a new expression to calculate the capacity of bearing plates, which accounted for the effects of sands compaction and dilation. By extrapolating the findings of these tests to a hypothetical scenario, a model design problem was described where the length of a pile can be reduced by 20% to 60% (depending on the load) by using a plate attached to the pile. The results of this study can help designers to minimise penetration depth; thus, achieving a more economical and sustainable design.

By Christopher Jon Preston

This paper describes a type of ammonium nitrate (AN) produced in a patented experimental atomization/aerodynamic process. This AN exhibits outstanding properties for use as a main ingredient to a new family of AN-based commercial explosives. Micro-particle ammonium nitrate (MP-AN) is produced by atomizing either an 83% or 85% AN solution which has been doped with a two component surfactant NSol 1000 (NSol). NSol imparts some water-resistance as well as provides a means of increasing density and bulk strength. Increased detonation velocities, well in the range of emulsion explosives, can be achieved. The maximum manufacturing temperature is less than 100°C. The methodology has the potential of being environmentally friendly since any effluent can be recycled back into a make-up tank to be re-used by the closed loop method. The process has a small footprint.

Jan 1, 2015

By R. Hazael, R. Alford, R. Critchley

The ability to compare explosives is fundamental. Numerous methods are used and while simple conversion factors are often used, the use of TNT Equivalency (TNTe) is not a simple subject as explosives exhibit very different equivalencies depending on whether the pressure or impulse are being considered as well as other conditions. The scaled distance has been found to have a significant effect on the TNTe but due to the difficulty of taking measurements at very close ranges, no TNTe have been quoted for charges in direct contact (Z=0). This paper describes the use of a ballistic pendulum to measure the impulse from contact charges and presents some surprising results that require a two-stage propulsion, as originally described by Backofen, to be explained.

Jan 1, 2024