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By A. W. McReynolds

E. OROWAN*—I observed the phenomenon of jerky yielding many years ago with zinc25 and cadmium single crystals. A significant point was that the jerks occurred not only when the stress was raised but also (sometimes, after a pause of many minutes during which no trace of creep was observable) at constant stress. The phenomenon may be closely linked with the inertia of the testing machine and of the specimen, although the inertia alone cannot account for it. If, during the test, the resistance of the material to plastic deformation suddenly diminishes while the applied force remains constant, a sudden deformation follows until the yield stress has risen, by strain hardening, to the level of the applied stress (= the value of the previous "upper yield point."). When this is reached, the rate of deformation has attained a maximum value because, up to this moment, the applied force was higher than the plastic resistance of the specimen, and the difference was used for accelerating the moving parts of machine and specimen. The kinetic energy accumulated is now transformed into plastic work by further deformation; that is. the deformation overshoots the point at which the plastic resistance equals the applied static force. When the kinetic energy has been used up, therefore, we are left with a specimen the yield stress of which is higher than the applied stress, and no further deformation can occur (apart from a little creep) until either the applied stress has been raised to the new yield stress level, or the yield stress has fallen by thermal recovery to the level of the applied stress. While this occurs, a new upper yield point can develop, for example, by precipitation.26

Jan 1, 1950

By John Branner

FIVE of the geologic horizons that yield oil in other parts of the world are represented in Brazil; namely, the Devonian, Carboniferous, Permian, Cretaceous, and Tertiary. Thus far, the first two have shown no, evidences of being oil bearing within Brazilian territory. Not enough exploring has been done to permit trustworthy comparisons of the relative importance of the Permian, Cretaceous, and Tertiary as oil-bearing horizons in this country. The most important, indeed almost the only, information available relates to the locations of the areas and to the structural features of the several horizons. The theories regarding the physical conditions under which these rocks were laid down, however, I regard of the utmost importance. PERMIAN Rocks of Permian age cover an enormous area in Brazil, extending from Rio Grande do Sul to Maranhão on the north, and to Matto Grosso on the west. These Permian rocks in many places are known to include oil-bearing shales and in some locations contain small veins of gilsonite. The geologic map of Brazil shows that the Permian area is widely distributed, but there is considerable doubt about 'the origin of some of the rocks:. Some of the lower Permian beds in southern Brazil contain marine fossils, but in Minas no fossils have as yet been found in them, and in Bahia, at only one locality have a few Permian plants been found. Indications of oil have been found in the states of São-Paulo, Paraná, and elsewhere farther south, but wells drilled in the Permian of São Paulo near the Morro do Bofete did not find oil. One well has been started, by the Brazilian government, in the Permian of Paraná near Marechal Mallet, close to latitude 26° south, but thus far oil has not been found.

Jan 6, 1922

By C. F. Giermak

Over a considerable period of time great interest has been shown in selective dry concentration of fine ferromagnetic particles, although it is only recently that new permanent magnetic materials have been made available to permit building of such permanent magnetic separators. It is well known that the conventional drum separator does' not efficiently separate fine materials. The centrifugal force on any drum acts in accordance with the particle size and gravity, which may beat varying magnitude-.opposite to the magnetic force, especially when the material is not closely sized. The Magnetic-Mechanical Separator (MMS) is designed for the concentration of fine, unsized magnetic materials where the percentage composition of magnetics to nonmagnetics, or the nature and texture of the materials, is such that its unique agitation and shake-out action with no centrifugal force provides greater efficiency than is obtainable by conventional magnetic separation equipment. This machine consists of a complete double belt conveyor unit with a premagnetizing Axial Pole Agitating Pulley at the feeding end of the lower conveyor belt and a special agitating concentrator magnet above the lower belt of the upper conveyor.

Jan 1, 1965

An empirical method of estimating dense rock (D.R.E.) equivalent volumes erupted as airfall tephra, described in a companion paper in this volume, is elaborated, and its accuracy discussed. Estimates obtained from a single eruption can be classified as to whether they show positive, negative, or constant relative dispersion. For positively dispersed tephras (estimated volumes increasing with distance), this procedure improves the accuracy of the method. The technique is applied to selected andesitic tephras erupted from Egmont Volcano, New Zealand, during the last 28 000 years, which are found to range in volume from about 1.5 x 107 m3 up to about 2.4 x 108 m3 D.R.E. With a factor of about 16 between the smallest and largest volumes, this contrasts sharply with the rhyolite volcanoes in New Zealand, where the difference factor is usually of the order of 100. The largest tephra eruptions at Egmont are small compared to the largest debris avalanches, which have exceeded 1010 m3 (10 km3) in volume.The magnitude versus frequency relationship, calculated using a maximum likelihood method, establishes the limits of eruption magnitude at Mt Egmont as 107 to 109 m3 D.R.E. For some volcanoes, the magnitude-frequency relationship changes with time, owing to clustering of eruptions, separated by long dormant intervals. Ngauruhoe Volcano, New Zealand, is an example. Within eruptive episodes, the mean interval between eruptions of >_ 105 m3 is about 0.9 ¦ 0.65 years. The mean interval between eruptive episodes in which >_ 106 m3 is erupted, including episodes in which this volume is erupted gradually, is about 25.8 ¦ 6.6 years, and the mean dormant interval between all episodes is about 5.2 ¦ 3.0 years. At present Ngauruhoe is in an unusually prolonged dormant period, 50% longer than any in the historical record, since 1839.

Jan 1, 1990

By Henry D. Hibbard

A NOTED ordnance engineer once said to a friend, in speaking of the production of great steel guns, "How is it? We design our guns with a factor of safety of eight, and the guns burst." The vague way in which internal stresses and strains in iron and steel are often considered and spoken of makes it worth-while to examine them, as to their nature, their causes and results, how they may, for useful purposes, be advantageously dealt with, and how, when detrimental or dangerous, they may be reduced or kept within harmless proportions. Rankine defines ?strain " as a change of form or dimensions of a solid or liquid mass produced by a stress. This definition seems not intended to cover strains due to internal stresses, and it will help us in the present inquiry to consider strain as a tendency to change as well as an actual change of form. Internal strains in iron and steel are the result of stresses within the mass of the piece, some parts pulling and others pushing in resistance to them; or, in other words, some parts are in tension and some in compression, each part striving to relieve itself from strain and make the piece assume a form in which all parts are at rest. Subdivision, so that each part could relieve its strain by motion relative to the other parts, would, if carried out far enough, practically obliterate strain. The internal strains we are now to consider are not those due to the stresses of the service which the piece is rendering, either alone or as, a part of a structure, which may be termed service-strains, but those which originate or at least are contained in the piece itself. Internal stresses in a piece of metal are, like action and reaction, always equal and in opposite directions. The stresses

Sep 1, 1906

By Raymond G. F

Geostatistics - a tool used by geologists and mine planning engineers to estimate grades and rapidly evaluate alternative mining strategies has reached an advanced stage of development for the silver-lead-zinc orebodies at Isa and Hilton Mines. Geostatistics has been used for over a decade in the massive copper orebodies but the stratiform lead-zinc orebodies are much more complex and provided a completely different set of challenges. Recent increases in computer processing speed and power provided by the Integrated Mine Planning System (IMPS) has aided the development of the geostatistics package. Also the formation of a project team and the subsequent in-house development which has drawn together the expertise of geologists, engineers and system analysts has contributed significantly to the success of the project.The most important feature of any approach to modelling the lead-zinc orebodies is that the kriging search must consider estimate and sample points according to their positions relative to bedding surfaces. By transforming co-ordinates as perpendicular offsets from a plane representing the local strike and dip, it is possible to elongate the ellipsoidal influence to parallel bedding. By interactively modelling surfaces using CAD facilities and then specifying these surfaces as 'hard' or 'soft' boundaries, the geologist has complete control over the kriging process.

Jan 1, 1993

By John H. Bell

R. B. T. KILIANI, New York, N. Y.-I wish to present some figures based upon actual observation extending over a few months time which seem to prove the author's conclusions. It is a comparison of two machines operating on the same ore, in the same plant, one taking the undersize of ½ -in. screen and the other taking the undersize of 8-mesh. Each of the machines was first operated as a pebble mill, with flint pebbles, in open circuit, then with metal pebbles in open circuit and, finally with metal pebbles in closed circuit. For the first case, the percentage of oversize on 48-mesh, Tyler screen, in the discharge, varied, in the mill taking ½ -in- feed, from 37.2 to 19.9 per cent. The second mill, taking the 8-mesh feed, had a variation in oversize on 48-mesh, from 36.8 per cent: to 0.5 per cent.; so it is seen there is considerable variation in these figures. I have computed the tons per kilowatt-day reduced through 48-mesh for each machine under each one of these conditions, giving 6 sets of figures. The first of these I called 1.0 and determined the ratio of the others to this.. In the snipe way, I figured the relative mechanical efficiency according to Kick's law, using' the figures given by Mr. Taggart in his paper, for ordinal numbers of the Tyler screens. I have also figured the efficiency in mesh-tons per horsepower according to Gates' method by plotting the screen analyses of feed and product and multiplying the area by a constant dependent on the scale used. The commercial efficiency of tons per kilowatt-day reduced through 48-mesh checks very closely with the efficiency by Rittinger's law, within 1 per cent. except in one case. By Kick's law, the efficiency checks fairly closely, within about 5 per cent., with the commercial efficiency of the mill grinding feed, but when we start to grind a finer, 8-mesh material, and especially grinding very fine; with a

Jan 4, 1917

This report presents production and delivered costs for coal exports from the five major Western coal-exporting countries: Australia, Canada. Colombia, South Africa, and the United States. Cost data were compiled from visits to 43 mines by U.S. Bureau of Mines engineers between 1985 and 1990. All report costs are in January 1989 U.S. dollars per short ton. Production costs for raw coal are divided into mining and regulatory categories. Costs are broken down by type of cost, type of mine. and country. Scheduled operating and capital costs for raw coal were processed by the Bureau's MINSIM discounted cash flow program to determine total production costs calculated at 0% and 15% discounted cash flow rates of return (DCFROR). Delivered costs are for salable coal delivered to various markets. Costs are broken down by supply country, market, and type of cost. Scheduled operating and capital costs for salable coal were processed by the Bureau's MINSIM discounted cash-flow program to determine total salable coal costs at 0% DCFROR. Added to total salable coal costs were transportation and port costs to get delivered costs. Comparative overview information on the coal industries of the five study countries are appended. This appendix includes information on industry economics and exports, production and reserves, and coal industry issues.

Jan 1, 1993

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least-radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By John H. Hild

The topography of the Jamestown fluorspar area is rough and ranges from 6,400 to 8,000 feet in altitude. Some fluorspar was mined as early as 1870, but mining really did not begin in earnest until 1940, and up to July 1947 it is estimated that 272,500 tons of fluorite was mined and milled. In 1947 the General Chemical Co. was mining fluorite and milling it in a 200-ton-a-day mill at Valmont, 7 miles east of Boulder, and the Ozark-Mahoning Co. was milling ore in a 100-ton-a-day mill at Jamestown, using ore mined, by H. M. Williamson & Son. These fluorite deposits comprise veins in a granite country rock. The Bureau of Mines drilled eight holes, aggregating 2,579.1 feet, on the Blue Jay vein; four holes, aggregating 1,434 feet, on the Chancellor; and one 350-foot hole on the Nations Treasure. Fluorite of a minable grade and width was found in 10 of the holes drilled. In this report the location and accessibility, physical, features and climate are described and a brief history of the district is given. The deposits and character of the ore and sampling and analyses are described, mine workings are outlined, and work performed by the Bureau of Mines is summarized. Diamond drill logs are shown in appendix I, and 'Sample analyses are tabulated in appendix II.

Jan 1, 1949

By Mario Samamé Boggio

El presente texto describe la producción del alcohol como alternativa energética -en tanto replantea la política energética y la inscriba en el contexto histórico, geográfico, económico, social, tecnológico, cultural, ecológico del país que habitamos y del mundo que nos rodea. En ese sentido, se revisa la producción del alcohol a través de la biomasa, el cual mejora el rendimiento de la combustión en un motor de combustión interna, obteniéndose un mayor octanaje y el alcohol etílico se puede obtener a partir de biomasas de tres orígenes: carbohidratos en forma de azúcar (caña de azúcar, melazas), carbohidratos en forma de almidón (yuca, maíz, papa); y carbohidratos de las celulosas (madera y residuos agrícolas).

Mar 1, 1983

A field trial of the prompt neutron-gamma SIROLOG technique was undertaken by the CSIRO - Division of Geomechanics at Callide Coalfields during July 1989. The trial investigated whether the sonde could reliably be used for the determination of Ash and Iron Oxide (Fe2O3) in coal seams, which had a highly variable iron content. Ten boreholes were logged, being water filled of a nominal diameter of 120 mm. The logging probe employed a 1.6 ¦g 252Cf neutron source and a 51 x 51 mm BGO detector. The source to detector distance was 15 cm. The results from one exploration borehole at the Dunn Creek Mine are discussed in the paper. The rms deviations for ash and iron determination between the neutron-capture predictions of the geophysical logs and the laboratory - chemical assays were 1.9 per cent Ash and 0.88 per cent Fe respectively. Using existing empirical equations which relate iron oxide concentration in coal ash to Initial Deformation Temperature (reducing conditions) at Callide, it may be possible to indirectly determine ash fusion properties as least as accurately, on a more detailed ply-by-ply basis, and more cost competitively than current laboratory techniques allow.

Jan 1, 1991

By C. D. Keith

Erie Mining Company, a pioneer in the iron ore pelletizing industry, has continued to develop methods and equipment to improve cost and quality. Under the management of Pickands Mather & Co., this property, owned by Bethlehem Steel Corporation, Youngstown Sheet and Tube Company, Steel Company of Canada, Ltd., and Interlake, Inc., has initiated a number of operating improvements for the taconite industry. One of the most noteworthy of these, which is applicable to the entire mineral industry, is the principle of fine screening with rappers (FSR). Erie's original efforts in the field of fine screening, which date back to 1961, were described in the April 1967 issue of the MINING ENGINEERING magazine. In that same month, Erie placed into operation a full scale PSR and regrind plant addition, capable of processing 10.3 million long tons of iron ore concentrates, produced by conventional taconite grinding, classification, and magnetic separation methods. Since this first successful commercial operation of the PSR principle et Erie, it has been applied in eight other iron ore beneficiation plants end is being tested by other U.S. and foreign companies. In addition to the use of PSR units at Erie Mining Company, Pickands Mather has applied PSR to other of its managed properties end to projects under development. This paper covers these applications as well as a now application at Erie Mining Company.

Jan 1, 1971

By R. E. McIvor, Brian Cornish, J. A. Finch, Yue Tan, Claude Gagnon

Fred C. Bond is recognized throughout the mineral processing world as the father of comminution equipment applied science and engineering. The Bond Work Index became a universal standard, and is the most widely used measurement tool for comminution energy consumption. This biography is the story of his lifetime of study, work experiences, experimentation, analyses and findings. His numerous published writings are reviewed. His legacy is one of comminution process engineering that will be used in perpetuity.

Feb 1, 2024

By L. W. Blau

THE entrance of geophysics and geochemistry into petroleum engineering may be viewed with apprehension by some engineers. They may not remember the time when "practical oil men" opposed the invasion of engineers into the field of petroleum production. By their excellent contributions they established themselves. In the popular mind, engis veers are practical men whereas physicists and chemists are suspected of being theoretical. It will be best to annihilate this misconception right now at the beginning of a closer relationship between petroleum engineers. geophysicists, and geochemists.

Jan 1, 1943

By BUREAU OF MINES

This report is submitted in accordance with the provisions of the Synthetic Liquid Fuels Act of April 5, 1944 (30 U.S C. 321-325, as amended), which require that: "The Secretary of the Interior shall render to Congress on or before the first day of January of each year a report on all operations under this Act." Owing to the broad scope of the content and the diversity of interests represented, the Annual Report for 1953 has been divided into two separate publications. Each has been published by the Bureau of Mines as a Report of Investigations, and the respective titles follow: R. I. 5043, Part I - 011 From Coal. R. I. 5044, Part II 011 From 011 Shale. - Identical in each report, the introduction summarizes research progress made in 1953 under the entire Synthetic Liquid Fuels program. A free copy of each of these publications may be obtained by a written request to the Bureau of Mines, Publications Distribution Section, 4800 Forbes Street, Pittsburgh 13, Pa. The R. I. number and title of the publication desired should be indicated.

Apr 1, 1954

By Boshou B

In China, there are approximately 3,000,000 million m3 of gas (methane) included in highly gassy mines liable to coal/gas outbursts; the amount of methane pre-drainage possible is estimated at 400,000 - 500,000 million m3. At present, methane drainage has been carried out in 110 mines with a total amount of 19,000 million m3 methane produced during the period of 198 1- 1986. The methane drainage in coal mines of China can be divided into three types: from adjacent seams, from working face seams and from goafs, all with good results. In recent years, general attention has been paid to integrating methane drainage into the mining system but methane drainage from old goafs has to some extent been developed as well.

Jan 1, 1988

By Yaroshenko YuG, Bokovikov BA, Gordon YaM

Problems of the effect of the number of tuyeres and their parameters on the uni- formity of gas distribution are invest- igated with the use of the authors' devel- oped mathematical model of the movement of gases and materials in the blast furnace. It is shown that the improvement of uni- formity of gas distribution with an increase in the number of tuyeres has a damping character. An analysis of the errors of the specified assumptions of the hypothesis concerning the potentiality of the gas movement in the bed is carried out. It is established that the potential approach model gives good results with the determination of the discharge of gas and its stress field, but is not useful for the calculation of local velocities of gas in the raceway. The results of trials of calculation investigations of the dynamics of form- ation of the raceway and the voidageòfield in beds of burden materials are presented in the concluding part of the paper.

Jan 1, 1981

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least- radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By C. F., Christopher

The purpose of any steel-making process is to convert the two raw materials iron and scrap into steel. The chemical analysis of the steel is set within certain limits which involve the physical proper- ties desired by the consumer. In addition to tensile properties a large number of other properties are at the present time desired, such as impact resistance, grain size regulation, specific degrees of hardenability, resistance to creep at high temperatures, resistance to expansion on heat treatment, the ability of the product to undergo extreme amounts of cold deformation without failure, and many other properties which are not directly related to the specified chemical analysis. Variations in many of the properties of plain-carbon steels are due to elements and compounds not included in the ordinary "five element"§ composition. Such variations result primarily from variations in oxidation of the metal in the furnace and from the deoxidation method employed. The steel-making problem therefore resolves itself into two distinct sections: (I) the elimination of certain elements from the charge (the iron and scrap entering the furnace) and the addition of materials to meet the chemical specifications for the heat; (2) the manipulation of the slag and metal and the process of deoxidation to give certain desired properties in the steel entirely apart from the chemical analysis specified. Each of 'these two ends must be attained

Jan 1, 1957