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By Robert H. Richards

The adaptation of European methods of concentrating ores to suit the conditions of this country has followed the lines that simplify machinery, diminish labor and increase capacity. Noteworthy instances are the substitution of hydraulic classifiers for the last one or two trommels in the series, and the substitution of a distributing-tank for the slimes in the place of the Spitzkasten. The question may be fairly asked, At what point do losses become serious in consequence of these changes? It is to study this question that the investigation herein described has been undertaken. After the losses are located and the methods of stopping them are pointed out, it will then lie with the individual mill to decide whether or not the plans proposed will save suficient value to warrant their adoption. In the discussion of sorting followed by sizing, as the terms are used in this paper, me have to deal with the preparation of slimes by the Spitzkasten for subsequent washing upon the slime-table. The Spitzkasten, or pointed box, is an inverted hollow pyramid, generally of wood, usually with four faces or sides coming together in a point below. The sides can have, according to Rittinger, a minimum angle of slope of 50" with the horizontal. The feed-water carrying fine slimes (less than 0.01 inch, or 0.25 mm. in diameter) for treatment is fed at one end and carefully distributed over the whole width. The outlet is over the opposite end. The water-current passes direct from inlet to outlet, and has usually been regarded as a surface-layer pass-

Jan 1, 1898

By George W. Goetz

As is well known, the general use of natural gas in Pittsburgh and vicinity for domestic and industrial purposes has shown the great advantages and benefits to be derived by the use of a gaseous fuel. In order to ascertain and bring together all the facts relating to a large and economical production, purification, distribution, and consumption of fuel-gas made out of coal, the Fuel-Gas and Electric Engineering Company, Ltd., was organized, under the presidency of George westinghouse, Jr.

Jan 1, 1890

By Joseph M. Jacisin

Fatigue tests were conducted on 2017-T4 alumium in alloy in an u1lrcthig.h vacuum of 2 x 10-lo Torr and in air. The vatio of vacuum-to-air faligue life for this ~malerial varied Jrom 3.5:1 at a strain of 2.5 X 1O-3 ill. pegr in. to 8:l at a strum of 3.3 x X ill. per 171. Sotlze pvelivtlinary data were also obtained on the faligue life of the alumirnum alloy in a dvy-nitrogen atmosphere. A dark deposit observed on the fracture surfaces of the aiv-tested specimens was identified as oxides of tr~angarzese and magnesium This observalion, and the close correlalion betaveen results obtained in vaCuum and dry-nitrogen environtments, tend to confirm that air stvongly influences the fatigue mechanism by a covrosion process. THE fatigue life of certain metals is known to increase when the atmospheric pressure is reduced. Gough and Sopwith1-2 postulated that this is due to a joint chemical and mechanical process operating in air at the surface of the metal with oxygen and water vapor playing significant roles. Wadsworth and Hutchings3 observed that aluminum is mainly affected by the presence of water vapor. Very little information is available on the fatigue properties of structural aluminum alloys in a vacuum environment. This report describes work performed on 2017-T4 aluminum alloy in an ultrahigh vacuum (2 x 10-loTorr) and in air. Some preliminary data are also presented on the fatigue life of the alloy in a dry-nitrogen environment. 1) EXPERIMENT 1.1) Test Material. The material tested was commerciaT 2017-T4 aluminum alloy which, in addition to aluminum, has an approximate composition of 4 pct Cu, 1 pct Fe, 0.8 pct Si, 0.5 pct Mg, 0.5 pct Mn, plus smaller amounts of other elements.* Some typical naturally age to a substantially stable condition. Specimens were then machined from these rods and ground to a No. 8 microfinish. In order to minimize variation in material characteristics, specimens were made from rods procured from the same lot. 1.2) Apparatus. The apparatus and test specimen used in the fatigue tests are shown in Fig. 1. The device utilized a single-cantilever beam with rotating-bending loading. Bending stress was applied to the fatigue test specimen by placing a spacer beneath the bearing support, thereby providing a constant deflec-

Jan 1, 1968

By C. W. Macgregor

The observation of the flow layers, or Luders' lines, produced in mild steel when it is stressed into the plastic range often provides considerable useful information for the study of the fundamental mechanism of the plastic flow of metals. It is a commonly observed fact that as soon as the upper yield point in a mild-st'eel tensile-test bar is passed, an unstable condition develops in the equilibrium, the load on the testing machine drops and if the surface of the bar contains a thin mill scale, the latter begins to flake off rapidly along certain "lines." These "lines" are ill reality traces of wedge-shaped flow layers and are formed by the inter-section of the surface of slip and the surface of the bar. The average plane of the flow layer itself has been found by various experimenters to be inclined at an angle of approximately 45" to the axis of the test bar. In a body of more complicated shape stressed in possibly a different man-ncr, the tangent planes to the flow layers at each point seem in many cases to be inclined at an angle of about 45" to the principal stress direct-tions at the point. As examples of the latter may be mentionecl the logarithmic spirals obtained when a rivet hole is punched in a thin plate, or when a tube is subject,ed to internal pressure only, etc. IIencc if the flow layers are observed from an experiment, the shear-st'ress trajectories —the curves indicating the direct,ions of the maximum shearing stresses in the body—may then be approximately determined. Since the latter curves form an orthogonal family inclined at 45" to the principal stress directions, the family of principal stress trajectories, or the curves irldicating the directions of the principal stresses, may be thus obtained Although the discontinuous type of stress-strain curve at the yield point is commonly observed with test bars of mild steel, more recent experiments have shown that this is by no means the only material exhibiting this interesting phenomenon. A similar effect has been observed in zinc and cadmium crystals, by Becker and Orowai~; in duralumin and other aluminum alloys, by Dawidenkow,~Elam,~ Fell4 an(l others; in copper and copper-alloy crystals, by Elam;~ in brass by Elam;3 in brass wires by deForest;" in higher carbon steels, tungsten steel, and

Jan 1, 1939

By C. W. MacGregor

The observation of the flow layers, or Luders' lines, produced in mild steel when it is stressed into the plastic range often provides considerable useful information for the study of the fundamental mechanism of the plastic flow of metals. It is a commonly observed fact that as soon as the upper yield point in a mild-st'eel tensile-test bar is passed, an unstable condition develops in the equilibrium, the load on the testing machine drops and if the surface of the bar contains a thin mill scale, the latter begins to flake off rapidly along certain "lines." These "lines" are ill reality traces of wedge-shaped flow layers and are formed by the inter-section of the surface of slip and the surface of the bar. The average plane of the flow layer itself has been found by various experimenters to be inclined at an angle of approximately 45" to the axis of the test bar. In a body of more complicated shape stressed in possibly a different man-ncr, the tangent planes to the flow layers at each point seem in many cases to be inclined at an angle of about 45" to the principal stress direct-tions at the point. As examples of the latter may be mentionecl the logarithmic spirals obtained when a rivet hole is punched in a thin plate, or when a tube is subject,ed to internal pressure only, etc. IIencc if the flow layers are observed from an experiment, the shear-st'ress trajectories —the curves indicating the direct,ions of the maximum shearing stresses in the body—may then be approximately determined. Since the latter curves form an orthogonal family inclined at 45" to the principal stress directions, the family of principal stress trajectories, or the curves irldicating the directions of the principal stresses, may be thus obtained Although the discontinuous type of stress-strain curve at the yield point is commonly observed with test bars of mild steel, more recent experiments have shown that this is by no means the only material exhibiting this interesting phenomenon. A similar effect has been observed in zinc and cadmium crystals, by Becker and Orowai~; in duralumin and other aluminum alloys, by Dawidenkow,~Elam,~ Fell4 an(l others; in copper and copper-alloy crystals, by Elam;~ in brass by Elam;3 in brass wires by deForest;" in higher carbon steels, tungsten steel, and

Jan 1, 1939

By C. W. Arnold, H. L. Stone, D. L. Luffel

The purpose of this research is to determine (I) the efficiency of small banks of enriched gar driven by methane in displacing oil from a porous medium and (2) the effects of variation in bank size and composition of that efficiency. Most of the experiments were conducted in a sand-packed tube 20-ft long and 1/2-in. in diameter. The hydrocarbon system generally used was methane, butane and decane at 2,500 psia and 160°F. The results of these experiments indicate that, in the regions contacted by the gas, a small bank of an oil-miscible gas driven by methane can displace all of the oil in a piston-like manner. If the enriched gas is of such composition as to remain immiscible with the oil, displacement of oil is less efficient than for the miscible case, and the gas bank travels through the sand with a velocity less than that of the driving gas. These data along with theories discussed imply that smaller banks and less total gas are required when the enriched gas and oil are miscible. INTRODUCTION Widespread application of enriched-gas drive to the recovery of oil rests upon a key factor — the use of limited quantities, or "banks", of enriched gas. At the present time, the value of liquefied petroleum gas or other enriching agents discourages their use in a continuous injection technique, or even in a large bank, except in a few isolated reservoirs. If small banks of enriched gas driven by methane were as effective in displacing oil as is continuous injection, the enriched-gas drive process might be applied to a larger number of reservoirs. Previous research on the mechanics of the enriched-gas drive process reported by Stone and Crurnpl and by Kehn, Pyndus and Gaskell has utilized continuous injection of enriched gas. This work has shown that two types of displacements occur. With gases containing sufficient intermediates. the oil is displaced misciblv and complete recovery is obtained from the regions swept. When gases are used which contain insufficient intermediate hydrocarbon for miscible displacement, oil is displaced immiscibly. In the latter type, selective solution of the intermediate hydrocarbons causes a swelling and reduction in viscosity of the oil and leads to an increased recovery over that obtained by dry-gas (methane) drive. The size of the enriched-gas bank necessary for efficient displacement of oil is determined by those factors which cause deterioration of the bank. A differentiation may be made between those factors which operate on a microscopic scale and those which act on a macroscopic scale. On the smaller scale, the enriched gas mixes in the direction of flow by diffusion and convection with the fluids immediately preceding and following it. On the larger scale, the gas may by-pass the oil by flowing through permeable streaks, by overriding the oil because of density difference, or by fingering because of unfavorable viscosity ratios. In such cases, the enriching material tends to mix with the oil both laterally and in the direction of flow. The increase in effective area available for diffusion and dispersion of the enriching components leads to a faster degradation of the bank and a need for a larger bank than is necessary for those cases in which no by-passing occurs. The effects of such macroscopic factors in the deterioration of enriched-gas banks have been reported in a separate paper by Blackwell, Terry and Rayne. The present study was confined to the factors which operate on the smaller scale, in particular to the behavior of banks of enriched gas in sands uniformly swept by the gas. Experiments were designed to answer the following questions. 1. Can small banks of enriched gas driven by methane be used to secure oil recoveries comparable to those obtained by continuous injection of enriched gas? 2. What is the optimum bank size (the minimum bank size necessary to obtain a recovery comparable to that obtained by continuous injection of the same enriched gas)? 3. How many total pore volumes of gas must be injected to obtain the maximum recovery when the optimum bank size is used? 4. What is the effect of varying the number of enriching components in a gas bank? This report describes the experimental investigations and discusses the results in terms of their significance to reservoir behavior.

By Guy W. Crane

The geology of the Tintie mining district, fully treated, would occupy an elaborate monograph. This less comprehensive paper is devoted primarily to the occurrence and origin of the orebodies of the district, while space is given to those phases of the general geology only which seem necessary to a proper setting of such a discussion. The first geological report on the Tintic district to be issued was that by Tower and Smith, published in 1899, in the form of a paper in Part III of the Nineteenth Annual Report of the U. S. Geological Survey, and also as Folio No. 65, Geologic Atlas of the United States. About four years ago a second investigation was begun by Waldemar Lindgren and G. F. Loughlin, of the U. S. Geological Survey. With the exception of a paper on the oxidized zinc ores of the Tintic district by Mr. Loughlin, the results of their work are still unpublished. The writer's acquaintance with the district began in the fall of 1913, and has extended over a period of about two years. 1. Location The Tintic district lies about 65 miles due south of Salt Lake City, and on the west central slope of the Tintic Mountains, a short range, which forms the connecting link between the Oquirrh Mountains on the north and the Canyon Range on the south—the group constituting the first of the Basin ranges to the west of the Wasatch Mountains. The productive portion of the district embraces an area about 6 miles long and 2 miles wide, which is divided between Juab and Utah Counties. Within this area are the towns of Eureka, Mammoth, Robinson, Silver City, and Knightsville. All these points are tapped by the Denver & Rio Grande and S. P., L. A. & S. L. Railways. 2. Topography As in most of the Basin ranges, topographic relief is strong, dropping rapidly from peaks of 8,100 ft. above sea level to elevations of 5,600 ft. in Tintic Valley on the west and 4,500 ft. in Goshen Valley on the east.

Jan 1, 1916

By M. Gell, G. R. Leveran

The high- and low-cycle fatigue properties of the nickel-base superalloy, Mar-MBOO, in columnar-grained and single-crystal forms were determined at room temperature. It was found that the fatigue lives of these materials were greatly affected by the size of preexisting cracks in MC-type carbides contained in the micro structure. Most of the data falls on two curves given by: (zN)'/A€= K, where Nf is the number of cycles to failure, Af is the total strain range, and K is a function of carbide size. No difference was observed in the fatigue behavior of the columnar-grained and single-crystal materials for the same MC carbide size. Matrix slip and crack initiation occurred at precracked MC carbides and, to a lesser extent, at micropores. Fatigue crack propagation was mainly in the Stage I mode, i.e., on cry stallo graPhic slip planes. The Stage I fracture in these materials was unusual in that distinct features were observed on the fracture surfaces. In high-cycle fatigue, these features resembled those commonly observed on the cleavage fracture surfaces of bcc and hcp materials. Yet, in this study, the cracks propagated slowly in a cyclic manner. In low-cycle fatigue, the Stage I facets contained equiaxed dimples, similar to those observed on the tensile fracture surfaces of ductile materials. These observations indicate that both local normal and shear stresses are involved in these Stage I fractures. A model is proposed to explain these results based on the weakening of the cohesive energy of the active slip planes by reversed shear deformation and the fracture of the bonds across the weakened planes by the local normal stress. RECENT developments in casting technology have produced cast nickel-base superalloys in columnar -grained and single-crystal forms.1'2 The tensile and creep properties of the nickel-base superalloy, Mar-M200, cast in these forms have been shown to be superior to the corresponding properties of the conventionally cast polycrystalline material.lp2 This improvement in properties results, in part, from the elimination of grain boundaries in the single crystals and the alignment of the grain boundaries parallel to the stress axis in the columnar-grained castings. As part of a program to evaluate the fatigue properties of nickel-base superalloys cast in single-crystal and columnar-grained forms, a study has been made of the cyclic deformation and fracture of Mar-M2OO at room temperature. M. fiFl I .hininr Mpmher AIMF ic ^pninr Rocoarrh Accn^iata anH I) EXPERIMENTAL PROCEDURE The composition range of Mar-Ma00 in weight percent is: 8 to 10 Cr, 9 to 11 Co, 11.5 to 13.5 W, 0.75 to 1.25 Cb, 1.75 to 2.25 Ti, 4.75 to 5.25 Al, 0.01 to 0.02 B, 0.03 to 0.08 Zr, 0.07 to 0.12 C, bal. Ni. All of the castings met the above specifications. The castings were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr which resulted in a 0.2 pct offset yield stress of 150,000 psi at room temperature. The microstructure of the material consisted of cuboidal, coherent particles of ordered, fcc Ni3(A1,Ti) (commonly designated y'), approximately 0.3 p on edge, distributed in an fcc y solid-solution matrix. MC carbides together with shrinkage and gas micropores were also distributed throughout the materials. The MC carbides and micropores were located preferentially in the interdendritic interstices, as well as in the grain boundaries in the columnar-grained castings. The (100) direction of all the single crystals and the common (100) axis of the grains in the columnar materials were aligned within about 5 deg of the specimen axis. Fatigue testing was carried out in the high-cycle (HCF) and low-cycle (LCF) fatigue regions, with the major difference being gross yielding of the specimen occurred during the first cycle in the LCF region. This division also corresponded with the more usual one in which the life of a specimen in LCF is less than lo4 cycles and that in HCF is greater than lo4 cycles. The designs of the high-cycle fatigue and low-cycle fatigue specimens are shown in Figs. l(a) and (c), respectively. The gage sections of both HCF and LCF specimens were electropolished prior to testing. The HCF specimens were tested in an MTS, closed-loop, hydraulic fatigue machine at 10 cps in air. The specimens were cycled between a tensile stress of 5000 psi and a maximum tensile stress which ranged from 35,000 to 125,000 psi, Fig. l(b). The LCF specimens were cycled under strain control from zero to a maximum tensile strain, Fig. l(d), in a Wiedemann-Baldwin testing machine. The experimental procedure has been described elsewhere.3'4 Both HCF and LCF tests were interrupted periodically in order to replicate the development of slip and cracking at the specimen surface. This was accomplished by placing plastic replicating tape around the gage section of the specimen while the specimen was in the mahine. The size of the MC carbides for all specimens was measured on a polished longitudinal section through the gage section after fatigue testing. The method of measurement consisted of carefully scanning the entire polished section in order to locate the largest MC carbides. Photographs were then taken of the six longest carbides oriented approximately normal to the

Jan 1, 1969

By T. Egleston

THE works of the Ore Knob Copper Company are situated in the county of Ashe in the northwestern part of the State of North Carolina, about ten miles from the Virginia line, at an elevation of 4600 feet above the sea. The nearest railroad station is at Marion, Smythe County, Virginia, about forty-five miles distant. The roads from the railroad to the works have been constructed by the company for the transportation of their material, and are very hilly, and in certain seasons of the year in bad repair. Transportation is therefore always limited and never easy, although it is done by contract at a very low price. The main difficulty with the transportation is not so much its cost as the fact that it puts a limit to the production of the works. These unfavorable conditions make it necessary for the owners of the mine to smelt their ores and to send to market nothing except the metal, which alone will bear the cost of transportation. The mine was opened previous to 1860, but has only been worked systematically during the last five or six years. The vein is a fissure vein from ten to twenty feet in thickness in the gneiss of the

Jan 1, 1882

By T. Egleston

The works of the Ore Knob Copper Company are situated in the county of Ashe in the northwestern part of the State of North Carolina, about ten miles from the Virginia line, at an elevation of 4600 feet above the sea. The nearest railroad station is at Marion, Smythe County, Virginia, about forty-five miles distant. The roads from the railroad to the works have been constructed by the company for the transportation of their material, and are very hilly, and in certain seasons of the year in bad repair. Transportation is therefore always limited and never easy, although it is done by contract at a very low price. The main difficulty with the transportation is not so much its cost as the fact that it puts a limit to the production of the works. These unfavorable conditions make it necessary for the owners of the mine to smelt their ores and to send to market nothing except the metal, which alone will bear the cost of transportation. The mine was opened previous to 1860, but has only been worked systematically during the last five or six years. The vein is a fissure vein from ten to twenty feet in thickness in the gneiss of the

Jan 1, 1882

By J. Offeringa, C. van der Poel

The report describes scaled model experiments on the recovery of oil from porous sands by the injection of miscible liquids [solvents] and the subsequent recovery of the solvents by water flooding. Special attention has been paid to the scaling problem. Scaling rules are deduced and their correctness is checked by carrying out experiments in tubes of various sizes. Data are submitted on the effect of the viscosity ratio oil-solvent on the efficiency of the displacement process, the viscosity ratio varying from 1.5 to 5,000. Breakthrough recoveries obtained when flooding with kerosene as a solvent, are equal to those obtained in water flooding at the same viscosity ratio, indicating that he phenomenon of viscous fingering is decisive. After breakthrough, however, flooding with a miscible liquid becomes much more efficient than a water flood and this is more pronounced as the viscosity ratio oil-solvent is higher. Although high oil recoveries are obtained and most of the solvent in the sand can be recovered by a subsequent waterdrive, a straight flood with miscible liquids does not appear economically attractive because of the large quantities of solvent required. Therefore, a circulation process is introduced, the features of which are described in this paper. Though by means of this circulation process the amount of solvent required can be drastically reduced, the process is not yet economic. SCOPE OF THE INVESTIGATION The recovery efficiency by water flood of oils of viscosities exceeding 50 cp is low. As interest in production of these highly viscous oils is growing at the moment, it was considered worthwhile to gain basic information on the feasibility of first flooding such oils with a low viscous miscible liquid [solvent] and subsequently producing the latter in a conventional way, e.g. by water flooding. The method has the obvious drawbacks that return on the investment is delayed until water flooding has begun and that it requires the investment of a more valuable product to produce a less valuable one. On the other hand, it may be expected that the displacement of one liquid by another is more efficient when the two liquids are miscible than when they are immiscible. As laboratory data on this point are scanty, the present investigation seemed justified. Another argument for carrying out these experiments is that they present a valuable contribution to our concepts of the scaling problem in reservoir engineering studies. Some major difficulties which are encountered in the scaling of the waterflooding process such as the scaling of the capillary forces and the difficulty of obtaining the same permeability characteristics in the model do not present themselves in this case. As the fluids are miscible capillary forces do not play a role and as there is only one fluid phase, Darcy's law is valid in its original form. Consequently it is felt that the scaling rules can be deduced with a greater amount of certainty. An essential feature of the experiments is that they are scaled model ones, which are, however, somewhat

Jan 1, 1955

By F. C. Stanford

THE work of an engineer is to direct natural forces so that they bring about the results that he wishes to secure. Heretofore he has concerned himself chiefly with physical forces and inanimate objects, until he has secured a truly marvelous degree of control over them. The great problem of the present age is to secure a like degree of knowledge and control of the human factor. Progress has already been made along this line, but, it is only a beginning. Wilhelm Ostwald says that scientific knowledge enables a man to be a true prophet; but it must be remembered that a good many people do not seem to be able to maintain a high average in prophecy. In short, the average of knowledge is not equal to the average needs of the present time, but continually fails to keep pace with it. It has been aptly said that the really essential need of the period is for more brains; if we only had sufficient knowledge and sagacity we could not only solve all difficulties, but prevent them from arising. This generalization holds good for an industrial organization. The most vital need of the management is for more brains. The logical course for an engineer in charge of an industrial organization is, therefore, to direct whatever forces may be at his command toward the development, training, and guiding of all the brains in his organization. This is easier said than clone, for it involves the carrying on toward two objectives, the maximum of productive work, and the development of the individuals who perform it. This is essentially like the rebuilding and enlarging of a plant, keeping it in full operation the while. On the other hand, if the aim is merely for maximum production from an organization, without offering opportunity for development, the final outcome will necessarily be like that f a plant that is driven at full capacity without stopping for repairs or improvements; it eventually becomes so run down that either a complete rebuilding is necessary or else it has to be abandoned.

Jan 2, 1918

By Donald C. Myntti

Modern open-pit mining can be described as a capital-, labor-and energy-intensive, large-scale, mechanized, and highly repetitive bulk material preparation and handling operation, with emphasis on the word "mechanized." In hard rock, this generally means shovels loading blasted materials into haulage units for transport to processing plants, stockpiles, or waste dumps. Mine management deals with several primary concerns on a daily basis; e.g.: Will any serious accidents and labor problems occur today, and will the tonnage targets be met considering the physical condition of the equipment? The latter subject will be discussed from a maintenance perspective. A successful, progressive heavy equipment maintenance program that protects company assets involves many elements. They include: •Proper equipment selection and procurement •Well-trained and motivated workforce •Good shop facilities •Preventive maintenance (PM) program •Warehouse support •Operations-maintenance department cooperation •Meaningful paperwork

Jan 3, 1978

By Frank C. Appleyard

Southwest of the town of Saltville in western Virginia is Plasterco, a small village that has been a source of gypsum production since 1815. Boasting the deepest underground gypsum mine in the world, Plasterco has been the site of mining operations by United States Gypsum Co. for more than half a century. And although its own ore supply is dwindling, Plasterco's position as a source of gypsum and gypsum products has been ensured by the recent opening of the nearby Locust Cove mine, one of U.S. Gypsum's newest projects. In the early days, production of gypsum at Plasterco was very small, the primary use of the mineral limited to that of "land plaster"-ground gypsum spread on the land to sweeten the soil. Initial mining was confined to surface outcrops containing gypsum, but the construction of a local plaster-producing calcining plant in the late 1800's coupled with al- most total depletion of the surface rock spurred the start-up of underground operations.

Jan 3, 1965

By F. C. Stanford

The work of an engineer is to direct natural forces so that the: bring about the results that he wishes to secure. Heretofore he ha concerned himself chiefly with physical forces and inanimate objects until he has secured a truly marvelous degree of control over them The great problem of the present age is to secure a like degree of know1 edge and control of the human factor. Progress has already been made along this line, but it is only a beginning. Wilhelm Ostwald says tha scientific knowledge enables a man to be a true prophet; but it must be remembered that a good many people do not seem to be able to main tain a high average in prophecy. In short, 'the average of knowledge is not equal to the average needs of the present time, but continually fails to keep pace with it. It has been aptly said that the really essentia need of the period is for more brains; if we only had sufficient knowledg and sagacity we could not only solve all difficulties, but prevent then from arising. This generalization holds good for an industrial organization. Th most vital need of the management is for more brains. The logica course for an engineer in charge of an industrial organization is, therefore to direct whatever forces may be at his command toward the development training, and guiding of all the brains in his organization. This is easie said than done, for it involves the carrying on toward two objective: the maximum of productive work, and the development of the individual who perform it. This is essentially like the rebuilding and enlarging of plant, keeping it in full operation the while. On the other hand, if th aim is merely for maximum production from an organization, withou offering opportunity for development, the final outcome will necessari be like that of a plant that is driven at full capacity without stoppin for repairs or improvements; it eventually becomes so run down th either a complete rebuilding is necessary or else it has to be abandone

Jan 1, 1918

By John C. LaScola, David M. Hyman, William P. Diamond

The U.S. Department of the Interior, Bureau of Mines, has established a computer-implemented coalbed methane data base containing data representing over 2,000 coal samples from approximately 250 coalbeds located in 17 States and one Canadian Province. Space for approximately 130 sample characteristics is reserved for each sample record and is divided for access efficiency into three separate physical files. A software package was written to provide a user-friendly environment in which the three files can be manipulated simultaneously. These files can be used interactively in DATATRIEVE 11, a commercially available sorting, retrieval, and report-writing software package or in any FORTRAN-compatible system for statistical analysis. The data base has been established for coalbed methane research in response to the health and safety needs of the mining industry. Possible applications of the data base include mine planning related to the occurrence of gas, as well as delineating areas of resource recovery and utilization.

Jan 1, 1983

Geological Survey of Alabama, University, Ala. A complete list of publications will be sent upon request Requests for publications should be addressed to Walter B. Jones, State Geologist, University, Alabama Publications of the Survey, of most interest to the general public, comprise (1) Special Reports, (2) Monographs, (3) Bulletins, (4) Circulars, (5) Maps The Special Reports mostly deal with a special coal field, mountain, valley, or series of formations, while the Monographs treat of some industry, resource, or group of organisms throughout the state or as far as it extends The Bulletins deal with a variety of subjects, but are usually smaller and less technical than the Monographs and Special Reports Maps now available comprise a map of the Cahaba coal field, one of the Coosa coal field and a small geological map of the state, in addition to a large geological map, 28 by 42 inches, 8 miles to the inch (1926) (also bound with Special Report 14) Price of the large geological map of Alabama, folded in manila envelope, is $1.03 postpaid

Jan 1, 1933

By A. D. Zunkel, A. H. Larson

Equilibrium arsenic contents of Pb-As alloys in contact with PbO-As2O3 slags containing less than 30 mol pct As2O3, were determined at 650°, 700: and 750 C in an inert at?rzosphere. In this temperature range, the arsenic content of the alloy increased with increasing temperature in the single-phase liquid slag region and decreased with increasing temperature in the two-phase slag region and the single-phase solid-solution slag region. The PbO-As2O3 phase diagram below 22 mol pct As2O3 was determined by thertrzal analysis and by application of a log ?As2O3/?PbO vS log XAs2o3 /x3pbO plot determined from the equilibrium actiuity data. The resulting phase diagram was not well-defined since the eutectic temperature was not detected in the thermal analysis experiments, although a region of terminal solid solubility of As2O3 was found. Results from the phase diagram determination are compared with an existing diagram in the literature. THIS experimental investigation is an extension of a study by the authors1 on the slag-metal equilibria in the systems concerned with commercial lead refining processes such as softening and dross fuming. The first part of this investigation was a study of the slag-metal equilibria in the Pb-PbO-Sb2O3 system. The only experimental work previously done on the Pb-PbO-As2O3 system was by Pelzel2,3 in which the phase diagram for the PbO-As2O3 system was determined below 50 wt pct As2O3 and the equilibrium constant for the reaction 3Pb + As2O3 + 3PbO + 2As was determined as a function of temperature. No slag-metal equilibrium data have been determined. It is due to the scarcity of information regarding the Pb-PbO-As203 system that this work was undertaken. This paper describes the determination of the slag-metal equilibria in the Pb-PbO-As203 system by equilibrating Pb-As alloys with PbO-As2O3 slags in an inert atmosphere, the effect of 1 wt pct additions of bismuth and copper on the slag-metal equilibria, and the PbO-As2O3 phase diagram both by thermal analysis and the use of the slag-metal equilibria data. EXPERIMENTAL Materials. The materials used in this investigation were analytical reagent-grade and assayed as follows: 1) 99.8 pct PbO (0.014 pct insoluble in CHJCOOH, 0.02 pct not precipitated by H2S, 0.1 pct CaO, and 0.08 pct SiO2); 2) 99.95 pct As2O3; 3) 99.99 pct Pb; 4) 99.0 pct As; 5) 99.99 pct Cu; and 6) 99.97 pct Bi. Room-temperature X-ray patterns revealed no detectable impurities in any of these materials. Apparatus for Equilibrium and Thermal-Analysis Determinations. The resistance-heated crucible furnace used in this investigation employed nichrome elements and was mounted so that it could be raised to surround the reaction tube during each experiment and, subsequently, lowered. A schematic diagram of the apparatus is shown in Fig. 1. Each charge was heated in a 3+-in.-OD by 31/2-in.-high 416 stainless-steel crucible placed in a 41/4-in.-1D by 18-in.-long fused-silica reaction tube which was closed at one end. On a shoulder around the crucible was placed a 3: -in.-OD by 12-in.-long open-end fused-silica condenser tube. The open end of the reaction tube was covered by a water-cooled brass cap with ports for 1) admitting an inert atmosphere to the system through a stopcock, 2) introducing a stainless-steel, motor-driven, paddle stirrer into the crucible, 3) evacuating the system with a mechanical vacuum pump, and 4) sampling the melt with Vycor sampling tubes. The brass cap was fitted to the open end of the reaction tube with a silicone gasket and collar clamp. The furnace temperature was controlled by a Barber-Coleman Capacitrol controller and a chromel-alumel thermocouple. Due to the corrosiveness of the melt, the controlling thermocouple also served as the measuring thermocouple. The temperature of the melt was calibrated against the controller temperature and was checked periodically during each test with a Vycor-enclosed calibrated chromel-alumel thermocouple. The temperature measurement and control can be considered accurate to ±3°C. Procedure. The charge placed in the crucible for each experiment consisted of 1000 g of Pb-As alloy and 300 g of PbO-As2O3 slag. The crucible was then placed in the reaction tube, the condenser tube was placed on the shoulder of the crucible, the silicone gasket and brass cap were fitted on the open end of the reaction tube, and the entire system was evacuated and filled with argon ten times. After the last flushing, a positive argon pressure of 1 psig was impressed on the system. The furnace was then raised to sur-

Jan 1, 1968

By S. S. Solomons, V. H. Tillmann, L. Smaniotto

INTRODUCTION The Zinc Corporation, Limited and New Broken Hill Consolidated Limited (ZC/NBHC) mines are situated at Broken Hill, New South Wales, Australia (refer Fig. 1). Both companies are wholly owned subsidiaries of Australian Mining and Smelting Limited (AM&S). Annual production from both mines is 2.3 million tonnes of lead, silver and zinc ore mined by a variety of underground methods. From 1911 to 1968, conventional overhand cut and fill stoping (both open and square set timber) was used almost exclusively, though some trials with shrinkage and sublevel stoping were undertaken. The trial stopes used short holes in conparison with today's sublevel open stopes. Mechanised cut and fill methods with regular rockbolt support were introduced in the early 1960's and undercut and fill stoping replaced square set timber stoping for pillar extraction in the late 1960's. Since 1968, increasing emphasis has been placed on longhole open stoping (LHOS) although some areas of the orebodies are comrnrnitted to the abovemehtioned methods since existing stope development makes it impracticable to change. In 1979, approximately half the total production was mined by LHDS and it is expected that the LHOS proportion will increase in the future. A vertical crater retreat method of longhole mining has also been successfully introduced to replace the undercut and fill stoping of some pillars and it is expected that this stoping method will be used in some future primary ore extraction. This paper reviews the progress of LHOS technology at ZC/NBHC with emphasis on the stope planning and design process and the importance of rock mechanics applications. The objective has been to maximise the primary extraction of the orebody giving due consideration to stability and safety. This has led to the design of a novel sloped wall longhole stoping method which should eliminate the formation of pillars by mining the orebody in a "continuous" manner incorporating a sloped sand interface between the blocks of ore being mined and the previously mined sandfilled stope. The expected results include the complete extract of the orebody without the formation of pillars and with minimal dilution of ore with sandfill. The evolution of the method can be best illustrated by following the mining progress of the relatively new Southern 'B1 Lode orebody at the NBHC mine. GEOLOGY Southern '8' Lode is the southern extension of the 'Bt Lode orebody, which is currently being mined further to the north in ZC/NBHC (refer Fig. 2). The ore block being developed and stoped extends for a vertical height of 90 metres from No. 17 level down to approximately ten metres above No. 19 level. The ore minerals are sphalerite and galena with the zinc:lead ratio averaging approximately 3:l with a minor amount of silver associated with the galena. There is a sharp contact between the ore and the country rock on the footwall and keel, while the hanging wall gradates into medium and low grade material. The gangue is primarily quartz together with garnet, biotite, feldspar, gahnite, sericite and minor apatite. In various horizons within the orebody, grey feldspar, quartz and garnet pegmatites occur as stratiform layers. The ore and country rock are competent with some inconpetent boundaries.

Jan 1, 1981

By Alan Arias

On grinding in pure water, zirconium, tantalum, iron, and stainless-steel powders were extensively comminuted and simultaneously oxidized with hydrogen release, whereas nickel, copper, and silver powders did not react with water and their particle sizes increased. On grinding nickel, copper, and silver in water pressurized with oxygen, nickel and copper became extensively comminuted and were oxidized, whereas silver did not react with oxygen and its particle size increased. From these results and other considerations , it is hypothesized that for extensive comminution of ductile metals and alloys to occur on grinding they must react with the grinding media. UlTRAFINE metal and alloy powders are finding an ever-growing number of applications in metallurgy and in other fields.' Of particular interest are ultrafine metal and alloy powders suitable for dispersion strengthening.2'9 Various research programs on dispersion strengthening are being carried out and in some of these programs the ball-milling method is being used to produce dispersion-strengthened materials. This method usually involves the simultaneous grinding of metal or alloy and a dispersoid followed by consolidation of the resulting powder mixture. To obtain the ultrafine powders required for dispersion strengthening,' grinding is carried out in many liquids, including aqueous and nonaqueous media, with or without grinding aids.4'5 Nonaqueous liquids usually contain water as an impurity and some grinding aids may contain water of hydration.5 The water present may affect the grinding process. The writer has shown5 that. on ball milling chromium in water, the chromium is oxidized and hydrogen is released. It was surmised that the same reaction may occur on ball milling other metals and alloys in waterbearing liquids. Therefore, the investigation of ball milling in water was extended to metals and alloys other than chromium. In the course of the investigation, however, it became apparent that the data-to-gether with the results from a few additional experi-ments—could be used to postulate a comminution mechanism for ductile metals and alloys. A well-known comminution theory is that of smekal.7 According to this theory, comminution is possible because of the weakening effects of surface cracks and other imperfections in materials. This theory imposes a lower limit of about 1 µm for the ground particles. The beneficial effects of liquids and additives on the rate of grinding are well known.8 Mechanisms by which liquids and additives may aid in grinding were reviewed by Rose and Sullivan.' One aspect of these effects is based on Rehbinder's theory of crack propagation in materials under stress.9 According to Reh-binder's theory, liquids or additives may promote the spread of cracks in stressed materials by lowering the surface tension at the crack tip. Rose and Sullivan surmise that the same mechanism may be operative during grinding, thereby facilitating comminution of the particles. In addition, Rose and Sullivan reviewed how additives may act as dispersants as a result of their being adsorbed on the surface of the particles being ground. This concept has been suggested by Quatinetz, Schafer, and smea15 to explain from their experiments the major role of additives that enabled them to grind metal down to 0.1 µm. Discussions of other comminution theories and additional sources of material on the subject will be found in Ref. 10. None of these previous suggestions and theories, however, can account for all phenomena encountered during ball milling of metals to submicron size in this and in a previous investigation by the author.6 The objectives of this investigation were to determine the behavior of metal powders during ball milling either in pure water or in oxygenated water and to gain an insight into the grinding mechanism. Zirconium, tantalum, iron, nickel, copper, and silver powders were ball-milled in pure water. These metals were selected because their oxides cover a wide range of free energies of formation. For comparison purposes, an alloy-type 430 stainless steel-was also ball-milled in pure water. The pressure of the hydrogen released during ball milling was monitored in order to determine the oxygen that combined with the metal or alloy. In order to obtain more information on the nature of the grinding process, nickel, copper, and silver powders were also ball-milled in oxygenated water (water pressurized with oxygen). The oxygen that reacted with the powders was determined from the pressure decrease in the mills. The powders resulting from ball milling in pure water and in oxygenated water were subjected to surface area, optical microscopy, and X-ray diffraction analyses. With these data, the oxygen calculated to be combined with the metals during ball milling, and comparison of the free energies of formation of the oxides of the milled powders with that of water, a comminution mechanism was postulated. MATERIALS, EQUIPMENT, AND PROCEDURES The materials used in this investigation were powdered metals, deaerated distilled water, high-purity helium, and commercial grade (99.5 pct purity) oxygen. The powdered metals used were zirconium, tantalum, iron, nickel, copper, and silver. A 16 pct Cr, ferritic stainless steel, type 430, was also used. The purities (or nominal compositions) and the surface areas of these metals and the alloy are given in Table I.

Jan 1, 1970