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By George A. Morrison

A deposit Of limestone Was known to exist at a depth of 2000 ft under the property of the Columbia Chemical Division of the Pittsburgh Plate Glass Co. at Barber-ton, Ohio. A 662-acre site was selected for the projected mine, some two miles northwest of the plant and near the main line of the Erie Railway. An electric railway 8800 ft in length connects the mine and the plant. The deposit is overlain by 18 ft of un-consolidated (sand and gravel), 100 ft of water-bearing sandstone, and finally 2080 ft of shale into which thin layers of sandstone are embedded. The limestone bed itself is 345 ft thick and overlies 200 ft of gypsum. A 300-ton-per-hour capacity mine was decided upon. Two shafts were deemed advisable, one for production and the second for service; and these were sunk 550 ft apart, one to a depth of 2323 ft and the other to 2258 ft. Each is 16 X , ft in the clear and timbered with 6-in. steel H-sets on 8-ft centers, using 3/8 X 4 X 4-in. angles as studdles. Twelve inch I-beams were used at 160 ft intervals as bearers set in deep hitches and concreted to a vertical depth of 8 ft. Wooden sheathing was first employed but sloughing of the shale created a pressure on this lining and finally concrete was deemed necessary. Water was encountered only within the first 315 ft, flowing at 60 gpm and by grouting this was reduced to 15 gpm. Temporary wooden sinking headframes were installed with 300 cu ft capacity storage pockets and with doors automatically controlled by air cylinders by hoistmen. Each shaft was operated on four 6-hr shifts. The usual V-cut was drilled at the center of the shaft and the round consisted of 34 holes- A 40 pet gelatin dynamite was employed with some 60 pet in the cut holes. Drilling crews consisted of four to six men. Shale drilled easily but became more bed in depth and sandstone wore away the gauge Of the bits rapidly. A room-and-pillar mining system was adopted whereby rooms turned off on 80-ft centers, each room 40-ft wide and 50-ft high. Rib pillars between rooms were cut into 100 ft lengths by frequent holes. Ventilation is achieved through the two shafts, the down-draft through the service shaft, and the return through the pr0duction shaft. The hoist has a a Of 300 tons per hour and is equipped with 10-ton balanced skips requiring. a 2-min cycle Or 30 trips Per hour- Hoisting is designed to Operate by automatic loading and no hoistman is required for normal Operation. The 48 X 60 in. jaw primary crusher is underground. It is fed through chute and chain feeders and is flood-oil lubricated and cooled. An inclined belt conveyor returns oversized material to the crusher. Tramming is by Diesel-powered trucks.

Jan 1, 1948

By George A. Morrison

A deposit Of limestone Was known to exist at a depth of 2000 ft under the property of the Columbia Chemical Division of the Pittsburgh Plate Glass Co. at Barber-ton, Ohio. A 662-acre site was selected for the projected mine, some two miles northwest of the plant and near the main line of the Erie Railway. An electric railway 8800 ft in length connects the mine and the plant. The deposit is overlain by 18 ft of un-consolidated (sand and gravel), 100 ft of water-bearing sandstone, and finally 2080 ft of shale into which thin layers of sandstone are embedded. The limestone bed itself is 345 ft thick and overlies 200 ft of gypsum. A 300-ton-per-hour capacity mine was decided upon. Two shafts were deemed advisable, one for production and the second for service; and these were sunk 550 ft apart, one to a depth of 2323 ft and the other to 2258 ft. Each is 16 X , ft in the clear and timbered with 6-in. steel H-sets on 8-ft centers, using 3/8 X 4 X 4-in. angles as studdles. Twelve inch I-beams were used at 160 ft intervals as bearers set in deep hitches and concreted to a vertical depth of 8 ft. Wooden sheathing was first employed but sloughing of the shale created a pressure on this lining and finally concrete was deemed necessary. Water was encountered only within the first 315 ft, flowing at 60 gpm and by grouting this was reduced to 15 gpm. Temporary wooden sinking headframes were installed with 300 cu ft capacity storage pockets and with doors automatically controlled by air cylinders by hoistmen. Each shaft was operated on four 6-hr shifts. The usual V-cut was drilled at the center of the shaft and the round consisted of 34 holes- A 40 pet gelatin dynamite was employed with some 60 pet in the cut holes. Drilling crews consisted of four to six men. Shale drilled easily but became more bed in depth and sandstone wore away the gauge Of the bits rapidly. A room-and-pillar mining system was adopted whereby rooms turned off on 80-ft centers, each room 40-ft wide and 50-ft high. Rib pillars between rooms were cut into 100 ft lengths by frequent holes. Ventilation is achieved through the two shafts, the down-draft through the service shaft, and the return through the pr0duction shaft. The hoist has a a Of 300 tons per hour and is equipped with 10-ton balanced skips requiring. a 2-min cycle Or 30 trips Per hour- Hoisting is designed to Operate by automatic loading and no hoistman is required for normal Operation. The 48 X 60 in. jaw primary crusher is underground. It is fed through chute and chain feeders and is flood-oil lubricated and cooled. An inclined belt conveyor returns oversized material to the crusher. Tramming is by Diesel-powered trucks.

Jan 1, 1948

By Vittal S. Bhandary, B. D. Cullity

Swaged iron wire has a cylindrical {001} <110> texture. The texture is also cylindrical after re-crystallization in the absence of a magnetic field, but <111> and <112> components are added to this texture when recrystallization occurs in a field. The mecizanical properties in tension and in torsion are not greatly altered by these changes in texture. AS shown in a previous paper,1 cold-worked wires of the two fcc metals copper and aluminum can be made relatively strong in torsion and weak in tension, or vice versa, by proper control of preferred orientation (texture). The deformation texture can be controlled by selection of the starting texture (texture before deformation), because certain initial orientations are stable during deformation. The present paper reports on similar work performed on bcc iron. In this case it was clear at the outset that there was no hope of controlling the deformation texture, which is one in which <110> directions are aligned parallel to the wire axis. (1t has usually been regarded as a fiber texture, but Leber2 has recently shown that it is a cylindrical texture of the type {001} <110>. In either case, <110> directions are parallel to the wire axis.) There is general agreement on this texture among a large number of investigators, which in itself suggests that the starting texture has no influence on the deformation texture. More direct evidence was produced by Barrett and Levenson,3 who reported that iron single crystals of widely varying initial orientations all had a single <110> texture when cold-worked into wire. Thus <110> is a truly stable end orientation for iron and probably for other bcc metals as well. Under these circumstances attention was directed to the possibility of controlling the recrystallization texture. This texture is normally <110> in iron,4 just like the deformation texture. However, it is conceivable that this texture could be modified by a proper choice of the time, the temperature, and what might loosely be called the "environment" of the recrystallization heat treatment. In the present work the environmental factor studied was a magnetic field. The effect of heating in a magnetic field ("magnetic annealing") on recrystallization texture has been investigated by Smoluchowski and Turner.5 They found that a magnetic field produced certain changes in the recrystallization texture of a cold-rolled Fe-Co alloy. The texture of this material is normally a mixture of three components, and the effect of the field was to increase the amount of one component at the expense of the other two. Smoluchowski and Turner concluded that the effect was due to magnetostriction. With the applied field parallel to the rolling direction, the observed effect was an increase in the amount of the texture component which had <110> parallel to the rolling direction. In the Fe-Co alloy they studied, the magnetostriction is low in the <110> direction and high in the <100> direction. Thus nuclei oriented with <110> parallel to the rolling direction will have less strain energy than those with <100> orientations and will therefore be more likely to grow. In a later paper on the same subject, Sawyer and Smoluchowski6 ascribed the effect to magneto-crystalline anisotropy and made no mention of magnetostriction. In the papers of Smoluchowski et al. the intensity of the magnetic field was not reported but it was presumably large, inasmuch as it was produced by an electromagnet. In the second paper6 it is specifically mentioned that the specimens were magnetically saturated. But if magnetostriction has a selective action on the genesis of stable nuclei during recrystallization, that selectivity must depend only on differences in magneto-strictive strains between different crystal orientations and not on the absolute values of those strains. Thus the saturated state does not necessarily produce the greatest selectivity, because the relative difference in magnetostrictive strains between different crystal directions may be larger for partially magnetized crystals than for fully saturated ones.7 In the present work the specimens were subjected to relatively weak fields (0 to 100 oe) produced by solenoids. MATERIALS AND METHODS Armco ingot iron rod (containing 0.02 pct C and 0.19 pct other impurities) was swaged from 0.25 in. in diam. to 0.05 in., a reduction in area of 96 pct. The mechanical properties in tension and torsion were measured as described previously.&apos; Textures were measured quantitatively with chromium or iron radiation and an X-ray diffractometer,8,1 and

Jan 1, 1962

By Walter P. Jenney

In the limestone area of Tintic and other mining districts of the Great Basin region of Utah, it has been observed that surface-outcrops of ore occur but seldom, and are mainly confilled to points of relatively low elevation, where the veins cross some basin or ravine. Nowhere does a considerable body of ore outcrop on the tops or high up on the slopes of the hills. Mining operations, on the other hand, have shown that large and continuous ore-deposits frequently occur in depth in the limestone, beneath large masses of barren rock. Such orebodies, when followed upward in the lodes, are found to terminate at well-defined levels, without reaching the surface. Yet the minerals-bearing fissures themselves extend above the top of the ore, being often traceable, though barren of all valuable minerals, for hundreds of feet above the stopes in the mines, and even observable in outcrops at the surface. This abrupt cessation of the ore at a uniform horizon does not appear to be connected with any change in the countryrock adjacent to the lodes. The strata above and below this horizon seem to be in every way equally favorable to ore-deposition. Explorations above it have developed an open-fissured country, barren not only of ore, but also of indications that minerals bearing gold, silver, lead or copper were ever deposited in the strata at that elevation. The height reached by the ore, while usually constant throughout the length of a given lode, may vary in particular sections, from the operation of local causes. Each lode in a district has its own distinct horizon, above which the oredeposits do not extend. Where the ore-bodies are continuous

Jan 1, 1903

By L. H. Simons, H. H. Spain

I NT RODUCTION Theory indicates that linear water-floods should exhibit scaling and stabilization properties in both oil-wet and water-wet porous media&apos;. Experimental verification of these proper-ties in oil-wet media was obtained some time ago&apos;, and more recently, Perkins&apos;, employing a high permeability unconsoli dated sand and a low oil-to-water viscosity ratio, has obtained flooding data in a water-wet medium which follow the pattern of scaling and stabilization. Also, Root and Calhoun3 have found similar trends in the displacement of gas by liquids from unconsolidated sands. In general, however, the experimen-tal evidence appears still somewhat conflicting since scaling and stabilization of water floods in water-wet media has not been observed in most of the studies to date&apos;.".&apos;. The purpose of this paper is to provide a more comprehensive picture of waterflood behavior in water-wet media and to corroborate the validity of the scaling and stabiliza-tion concepts. The need for differentiating between the intrinsic nature of water-oil displacements inside a porous medium and perturbating secondary end effects is discussed, pertinent experimental procedures are outlined and the results of flooding tests conducted at low and at high oil-to-water viscosity ratios on con- solidated, water-wet Alundum cores are analyzed. END EFFECTS IN WATER-WET MEDIA Outlet End Effects The peculiar feature of the outlet end effect in water-wet cores is that it not only results in an excessive wetting phase saturation at the outflow face,&apos;.&apos; but that it also retards the moment of water breakthrough: i.e., causes an undue delay in the appearance of water in the produced effluent. Conditions existing in a water-wet core when water first arrives at the outflow face are schematically shown in Fig. 1. At this flooding stage the saturation distribution, Fig. la, has not yet been distorted by the outlet end effect. A water-invaded pore at the outlet core face, opening into the oil-filled void space between the end of the core and the end plate of the flooding cell, is illustrated in Fig. lb. The curvature of the water-oil interface is concave toward the outlet, and the pressure on the water side of the interface is lower than on the oil side by an amount equal to a certain capillary pressure (Fig. lc). Before the water (of this particular pore) can be produced from the core, it is apparent that the pressure in the water phase must exceed that in the oil outside the core. Accordingly. when water first reaches the outlet face, it will not leave the core but will accumulate inside, and only oil will be produced. Eventually, as the water injection is continued. sufficient pressure is built up in the water to reverse the curvature of the interfaces in the outlet pores, and only then will water be produced from the core. This stage, illustrated in Fig. 2. corresponds to the conventional "water breakthrough" observed in flooding experiments. For purposes of discussion, it is convenient to distinguish between the flooding stage at which water first arrives at the outlet face of a core (Fig. 1) and the stage at which water is first produced from the core ( Fig. 2). The former will be referred to as "water arrival" and the latter water breakthrough. In oil-wet media

By William L. Saunders

MANY members of the Institute, who participated in the visit made, during the Bethlehem meeting of February, 1906, to the shops of the Ingersoll-Rand Company, at Phillipsburg, N. J., inspected with interest the new Electric-Air drill, which the company had set up for the purpose of showing it in actual operation to American. mining engineers. At the request of the Secretary of the Institute, I promised at that time to prepare a paper for our Transactions, describing the construction and advantages of the machine. But such a paper would then necessarily have contained much that was only expected or claimed by the designers and manufacturers of the drill, and not yet incontrovertibly proved by varied and long-continued practice. However moderate such statements might have been, they would have given inevitably to the paper, to some extent at least, the air of a prospectus, rather than of a technical contribution. I therefore decided, with the Secretary&apos;s approval, to postpone the writing of the promised paper until it could set forth the results of adequate actual practice, as well as the latest details of construction, etc., based upon practical experience. That period has now arrived. The Electric-Air drill has been exhaustively tested in the field, under varied and arduous conditions and upon the hardest rocks. It is now fairly in the field; its merits and performances are matters of unimpeachable record, and its place among established competitors can be definitely determined. As a representative of the Ingersoll-Rand Co., as well as a member of the Institute, I may be permitted to add that my company, being largely interested in the manufacture of air-

Jan 9, 1907

By R. N. Edmondson, L. Mair, M. Tenenbaum

It is the policy of The Metallurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers according to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editor, Dr. Gerhord Derge; Editorial Assistant, M. A. Redmyrski; Staff Coordinator, James J. Burke. THE METALLURGICAL SOCIETY: W. R. Hibbard, Jr., President; J. C. Kinnear, Jr., Past-President; John Chipmon, Vice President; T. D. Jones, Treosurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. w. Thornton, Chairman; Dennis Carney, John Chipman, J. C. Fulton I. H. Hollomon H. H. Kellogg, A. E. Lee, R. Maddin, J. D. Sullivan, and D. Swan. Review and selection of manuscripts is under the supenision of the following Publications Committees: Extractive Metallurgy Division: T. 0. King Chairman; S. J. Dickenson, R. P. Hermsdorf R. Schuhmann. Jr.. and P. T. Stroup. Institute of Metals Division: Robert Maddin, Chairman F. Lincoln Vogel Jr., Vice-chairman, W. A. Baikofen, R. W. Boliuffi J. H. Bechtold M. B. Beyer. R S. Busk, C. G. Gaetzel, Paul Gordon C. D. Groham, Jr., Robert F. Hehe-mann,&apos; R. I. Joffee, F. c. Joumot Jr lrving R. Kramer A. J. Lena Harold Morglin, C. J. McHargue, Russell A: Meussner, J. B. Newkirk H. W. Paxton, G. E. Pellissier, I. S, Servi, Alon U. Seybolt, A. J. Shaler, and Jack Washburn. Iron and Steel Division: J. C. Fulton, Chairman; T. B King, F. C. Langenberg, W. 0.. Philbrook, and T. 0. Winkler. Published bimonthly by the American Institute of Mining Metallurgical and Petroleum Engineers Inc., 29 West 39th Street, New York 18, N. Y. Telephon: pEnnsvlvanio 6-9220. Subscription 522 Per year for non-AIME members in United States and North South and Central America; $25 foreign;, $5 for AIME members. Single copies, 54.00, single copies foreign, $5.00. The AIME is not responsible for any statement made or opinion expressed In its publications . . . Copyright 1958 by the American lnstltute of Mining Metallurgical and Petroleum Engineers Inc. . . . Registered cable address AIME New York , . . lndexed in Engineering Index Industrial Arts Index and Chemical Abstrats . . . Application for second class mail privileges ii pending at New York, N. Y. Volume 212, Number 4.

Jan 1, 1959

By Nathan C. Rockwood

THE title of this paper, I understand, was suggested by professional mining engineers as an opportunity for someone to pose problems rather than to offer solutions for them, but the paper will merely attempt to pose some of the production problems of the mineral aggregates industry in such manner as to create professional interest in their solution by the mining engineer, geologist, geochemist and the metallurgical engineer versed in mineral-dressing technique. DEFINITION OF MINERAL AGGREGATES "Mineral aggregates" may be defined as fragments of any rock or mineral used to supply bulk or volume or substance for a given purpose. For example, mineral aggregates are used in portland-cement concrete to provide bulk with the expenditure of the least feasible amount of cement binder. Mineral aggregates are used without portland cement or bituminous binder in highway and railway roadbeds to provide substance, to carry loads. Mineral aggregates are used in filters for water and sewage, to provide substance for the liquid to trickle through. These are only a few typical uses of mineral aggregates. For all these uses, strength, toughness, resistance to abrasion, and durability are usually prime requisites; so, while theoretically mineral aggregates may be of any mineral composition, what really is desired is a mineral composition as nearly inert under the conditions of use as anything of earthly origin can be. EXPLORATION AND POSSIBILITIES OF DEVELOPMENT The distribution of deposits of mineral aggregate is universal, since almost any part of the earth&apos;s crust can be used; even the top soil is sometimes used in stabilized surfacing for highways or airport runways. Nevertheless there is ample opportunity for exercise of the talents of the mining engineer and the geologist in finding the particular deposit that will be most economical to develop, keeping in mind such considerations as: (1) quality and mineralogical characteristics of the material; (2) size and permanency of the market; (3) final cost of opening and development of the deposit; (4) selection of location of plant; (5) methods and costs of distribution of the product in comparison with both present and possible future competition; (6) selection of the proper type of operating equipment; (7) estimation of probable waste products and their disposal. These are typical but there are other considerations also. Because profit margins are far smaller than in any comparable mining operation, it is all the more logical to assume that a higher degree of expert knowledge is desirable to make a success of a mineral-aggregates business. The industry has much engineering talent in its operating branch, but it lacks, to a considerable

Jan 1, 1943

By J. E. Nesset, J. A. Finch

A model of the fully-loaded condition of particle accumulation on the matrix of a high gradient magnetic separator is developed. The model accurately predicts the build-up profiles reported recently by Friedlaender et al. A powerful development from the model is that loading (volume of accumulated material per unit volume of matrix) is uniquely defined by a dimensionless group, called the loading number, NL. From direct measurements, NL proved superior to the dimensionless group proposed by Watson as a measure of loading. The fine size limit of hematite recovery is examined using NL.

Jan 1, 1980

By Hillary W. St. Clair

An equation is derived for the rote of reaction of a sphere of metal oxide in a restricted enclosure through which a reducing gas is flowing. The equation takes into consideration the reaction rate coefficient, transport through the gas and through the porous shell of reduced oxide, the rate of gas flow, THIS paper describes a mathematical study of the chemical and physical processes that determine the rate of reduction of solid metal oxide with a reducing gas. The study was a part of a theoretical study leading to the development of a mathematical model for the simulation of the thermochemical behavior of the iron blast furnace. An essential feature of such and the volume of- space surrounding the sphere available for gas flow. The equation is applied to experimental data on vote of reduction of iron oxide in hydrogen. The equation serves as a model for predicting the course of reduction of a particle of. metal oxide in a shaft furnace. a model is an adequate mathematical relationship defining the rate of reaction in terms of all the important chemical and physical phenomena that affect the rate of reaction. This includes not only the reaction rate coefficients, equilibrium ratios, gas composition, and temperature, but also the relevant physical properties of the oxide, rate of gas flow, and relative volumes occupied by gas and solid. In many previous experimental studies of the rate of reduction of oxides by hydrogen or carbon monoxide, the rate of reduction was assumed to be controlled primarily by the chemical reaction at the

Jan 1, 1965

By A. J. R. Curtis

THE Portland Cement Association was organized more than a third of a century ago by a group of cement manufacturers, to do cooperatively the educational and research work needed to ensure proper use of their product. Specifically, the Association has a threefold purpose: (1) to search out facts to ensure the best possible service from concrete; (2) to give the widest possible circulation to facts affecting the use of concrete; (3) to urge practical application of those facts on actual building projects. An organization of technically trained men conducts many research projects in the Association laboratories, interprets their findings and applies them practically in the field. The net effect of this work has been to improve the design and prolong the life of roads, bridges, industrial, commercial and public buildings, homes, farm structures and concrete products. The results of this technical research and experimentation are made available to the entire construction industry through bulletins and reports. Information is also released to the general public through newspapers, magazines and Association publications. In addition to a1 technical staff in the general office in Chicago, the Association has district offices in 22 cities. Field engineers cover 37 states, the District of Colum-bia and British Columbia, to give service to users of Portland cement.

Jan 1, 1937

By L. W. Casteel

St. Joseph Lead Company&apos;s Southeast Missouri mines have been successfully converted to the use of ammonium nitrate and fuel oil as a blasting agent. This is significant to the company because it means a savings of a quarter of a million dollars per year. It is significant to the mining industry because of the unusual conditions involved and the methods and materials used to overcome them. St. Joe has been mining the low grade lead deposits of southeast Missouri since 1864. This ore occurs as disseminated galena in widely scattered pockets within the Bonneterre dolomite. The daily production of 20,000 tons is obtained from several hundred small, room and pillar stopes covering an area 10 miles long and five miles wide. Distribution of explosives and other materials is a real problem. Drilling in the stopes is done with air legs, column- mounted machines or jumbos, depending on the size and location of the stope. Drill hole sizes vary from 1 3/8-in. diam down to 1 1/8-in. Each driller charges his own holes and shoots them at the end of the shift. Numerous shafts provide natural ventilation which is supplemented in isolated areas by churn drill holes equipped with blowers. Water, in most stopes, is not a serious problem, although the mines do produce about 20,000 gpm.

Jan 5, 1962

By Donald P. Bellum, Lee Nugent

Southwestern Utah is well known for its scenic attractions. The beauties of Bryce Canyon, Zion Canyon and the Grand Canyon are of world renown. Thusly, Cedar City is known, at least by the local Chamber of Commerce, as the Gateway to the Utah Parks. However, of the thousands of tourists flocking to Utah&apos;s many points of interest by way of Cedar City, few realize that any mining takes place in the vicinity, in spite of the fact that iron mines have been in continuous operation for 40 years. The Pinto-Iron Springs Mining District is only 15 miles west of Cedar City, and is the largest iron ore producing district in the West. In recent years, the shipments have ranged from 2% to 4 million tons per year making Utah the fifth-ranking state in iron ore production.

Jan 11, 1963

By K. L. Ludeke, A. D. Day

For many reasons, it appears that deep rooted, perennial shrubs offer potential for improved stabilization and provide maintenance free vegetative cover to harsh sites where perennial grasses have not been successful. The major objective was to select various shrub species of arid plants for initial soil stabilization of disturbed mining areas. The very fact that a drought-adapted shrub has a massive root system that can use moisture from a greater volume of mineral waste soil materials suggests that arid environment disturbed soils may be vegetatively stabilized using desirable forage shrubs. A secondary effort is underway to assemble information and plant materials of promising species from many arid regions of the world for reclamation of mined lands. Surprisingly, many of the better plants for arid sites are quite high in protein content. With proper management, breeding, and selection, they may prove to be very desirable livestock feed when mined lands are used in range land areas. Advancements in arid land solid waste stabilization hold favorable promise for many industries that mine and mill in arid regions for effective reclamation of disturbed areas. Particularly exciting is the possibility of establishment of high density maintenance free vegetative cover of climax vegetation that reclaims the disturbed area back to its original land use. Due to high shrub productivity, stabilization potential, nutritional quality, and reclamation success, greater use should be made of shrubs in disturbed land reclamation associated with mining and milling operations in harsh aril environments.

Jan 1, 1986

By Frank Foote, E. R. Jette

Precision lattice-constant measurements have been widely used in the study of cubic solid solutions but as yet have been rarely applied to noncubic solid solutions. (See, however, references I and 2.) With the high precision at present attainable in the measurement of lattice constants, the X-ray method should be readily applicable to noncubic solid solutions. In the work reported here, hexagonal close-packed magnesium was used as the solvent and either lead, bismuth or gold as the solute. In the magnesium-lead and magnesium-bismuth systems the a and c lattice constants were determined as a function of composition, densities were calculated from these lattice-constant data, these theoretical densities were compared with those directly measured and the solid solubility limit was determined on quenched specimens over a considerable range of temperature. In the magnesium-gold system, the solid solubility is very small but we have obtained an indirect check on the solubility limit previously reported. Materials and Preparation oF the Alloys The magnesium used was obtained from the Aluminum Company of America and was 99.987 per cent pure. Impurities as reported On the label were: Fe, Al, 0&apos;004 per cent; Si, 0.009 per cent; Zn, trace; Cu, Pb, nil. The bismuth was Merck&apos;s analytical grade, minimum purity 99.95 per cent. Maximum impurities as listed on the label were: Fe, 0.008 per cent; Pb, 0.010 per cent; Ag, 0.010 per cent; Cu, 0.005 per cent; Sn, 0.003 per cent; Sb, 0.00; As, 0.000; S, 0.01 per cent. The gold was purified by double precipitation with sulphur dioxide. The lattice constants of these three metals have been previously reported.3 The lead used was test lead, silver free and with a maximum of 0.10 per cent heavy metal impurities. The lattice constant 01 this lead has been measured and found to be 4.94057 ± 0.00016 at 25°C. The alloys were prepared by melting together weighed amounts of the constituent metals in magnesia-lined alundum crucibles under an atmosphere of hydrogen purified by passing over magnesium heated to 500°C. The magnesia lining prevented contamination 01 the alloys with aluminum. Vacuum melting could not be used because of the volatility of magnesium. A high-frequency induction furnace was used for the melting operation and the stirring action of the current resulted in thorough mixing of the constituents. The melts were allowed to freeze in the crucible, the ingots obtained weighed about 10 grams. An extremely thin white film formed on the surface of the melts, sometimes covering only a part of the exposed surface. The ingots were filed clean, placed in small iror crucibles with close-fitting lids and indi. vidually sealed into Pyrex glass tubes Before sealing off, the tubes were alter

Jan 1, 1941

By Frank Foote, E. R. Jette

Precision lattice-constant measurements have been widely used in the study of cubic solid solutions but as yet have been rarely applied to noncubic solid solutions. (See, however, references I and 2.) With the high precision at present attainable in the measurement of lattice constants, the X-ray method should be readily applicable to noncubic solid solutions. In the work reported here, hexagonal close-packed magnesium was used as the solvent and either lead, bismuth or gold as the solute. In the magnesium-lead and magnesium-bismuth systems the a and c lattice constants were determined as a function of composition, densities were calculated from these lattice-constant data, these theoretical densities were compared with those directly measured and the solid solubility limit was determined on quenched specimens over a considerable range of temperature. In the magnesium-gold system, the solid solubility is very small but we have obtained an indirect check on the solubility limit previously reported. Materials and Preparation oF the Alloys The magnesium used was obtained from the Aluminum Company of America and was 99.987 per cent pure. Impurities as reported On the label were: Fe, Al, 0&apos;004 per cent; Si, 0.009 per cent; Zn, trace; Cu, Pb, nil. The bismuth was Merck&apos;s analytical grade, minimum purity 99.95 per cent. Maximum impurities as listed on the label were: Fe, 0.008 per cent; Pb, 0.010 per cent; Ag, 0.010 per cent; Cu, 0.005 per cent; Sn, 0.003 per cent; Sb, 0.00; As, 0.000; S, 0.01 per cent. The gold was purified by double precipitation with sulphur dioxide. The lattice constants of these three metals have been previously reported.3 The lead used was test lead, silver free and with a maximum of 0.10 per cent heavy metal impurities. The lattice constant 01 this lead has been measured and found to be 4.94057 ± 0.00016 at 25°C. The alloys were prepared by melting together weighed amounts of the constituent metals in magnesia-lined alundum crucibles under an atmosphere of hydrogen purified by passing over magnesium heated to 500°C. The magnesia lining prevented contamination 01 the alloys with aluminum. Vacuum melting could not be used because of the volatility of magnesium. A high-frequency induction furnace was used for the melting operation and the stirring action of the current resulted in thorough mixing of the constituents. The melts were allowed to freeze in the crucible, the ingots obtained weighed about 10 grams. An extremely thin white film formed on the surface of the melts, sometimes covering only a part of the exposed surface. The ingots were filed clean, placed in small iror crucibles with close-fitting lids and indi. vidually sealed into Pyrex glass tubes Before sealing off, the tubes were alter

Jan 1, 1941

By C. C. Harris

A critical literature review leads to a descriptive model of tumbling mill operation based upon energy partition concepts and the necessary requirements for particle fracture. As grinding proceeds into the ultra-fine region, conditions which are of little significance during normal operations gradually become controlling. These involve increasing resistance to fracture and an increasing tendency to aggregate as particles become smaller, and a growing fraction of the power input being consumed fruitlessly. The result is that fineness asymptotes to a maximum value as comminution proceeds indefinitely; thus where t is time, p and n are experimentally determined parameters, and Ø is a measure of fineness, which is presumed to be proportional to specific surface area, or proportional to the reciprocal of the size modulus (provided that the distribution modulus remains constant with time), or both. Ø, is the asymptotic value of Ø and is a measure of the grind limit. A method for its graphical determination is given. In a previous paper1 the physical and mathematical principles requisite to a study of the role of energy in comminution were reviewed. The micro-process of comminution — or the comminution event — can be investigated in terms of (a) the magnitude of the force-field localized around the individual particles which gives rise to the stresses generated in the particles, which in turn induces their fracture, and (b) the distribution of fragment sizes, should the event prove fruitful. The entire fragmentation operation can be considered to be the totality of its individual events, and in order to obtain a single independent variable of the process it is necessary to transform and sum the local stresses in terms of energy.1 This energy, however, will account for only a fraction of the energy input to the comminution process, the actual magnitude depending upon the kind of mill and several related factors. From the comminution viewpoint the primary function of a mill is that of stressing as many as possible of the individual particles of the charge to failure, with the maximum economy of energy expenditure. This is difficult indeed to achieve, for stressing a particle does not always break it, while the overwhelming portion of the energy input is involved with various internal mill processes which — almost incidentally — determine the magnitude, frequency, and manner in which the forces are applied to the particles. Essentially, these processes depend upon the mill dimensions, loading and speed, and they may be little affected whether fracture occurs or not. These processes must be delineated if a complete description of the role of energy in comminution is to be given; the energy account sheet1 (Fig. 1) in showing how the energy is partitioned for the requirements of the several functions it performs, provides a framework for the development of a model of the comminution process. Actual numerical values for the variables appearing in Fig. 1 will depend upon the mill, materials, and operating conditions. A possible general relationship between the variables will be suggested in this paper. Before proceeding further, a cautionary note must be issued. It was pointed out in an earlier paper&apos; that while energy input is not changed by increasing the power and decreasing the time in the same proportion, and vice versa, the results of the process in terms of particle fineness may be different. Thus, although energy is chosen as the independent variable of a comminution process, it is not absolutely independent, and care must be exercised to ensure that it is used within its range of valid application. Time has the necessary independence, and it will be used in place of energy where it is appropriate. The residence time in a mill is usually of the order of minutes. Under these conditions the particles are subjected to "... a relatively constant fracture producing environment".2 However, under the more rigorous conditions of greatly extended time, which pertain in ultra-fine grinding, indications are that the fracture producing environment no longer remains constant; this is the major subject of this paper. At this extreme limit the mill is probably taxed to its utmost, and at the same time the bulk material properties are becoming closer to ideal, while the physico chemical effects associated with surfaces, edges and corners are multiplying. (The edge length per unit volume is proportional to the square of the specific

Jan 1, 1968

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,&apos; later as agalmatolite,2 and finally as pyrophyl-lite, has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,&apos; which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments. The rocks in both zones consist of a great volcanic-sedimentary series, composed of air-laid and water-laid tuffs and breccias, lava flows, and slates. On the basis of composition, they may be classed into three groups: 1) tuffs, breccias, and lava flows of acid or rhyolitic composition; 2) tuffs, breccias, and lava flows of a basic or andesitic composition; and 3) water-laid slates composed of fine grained materials derived chiefly from the acid tuffs and breccias and

Jan 1, 1959

By G. Ansell, J. Weertman

G. Ansell and J. Weertman (Rensselaer Polytechnic Institute and Northwestern University, respectively) —The great increase in creep strength that you found in your indium-glass composites is quite striking. You ruled out a decrease in the dislocation source density as an explanation of the reduced creep rates. Could you tell in greater detail why you feel this is an inadequate explanation of the phenomenon. It appears to us that it is a reasonable one. Consider the spacing between the glass spheres in your composites. It is of the order of 10-3 cm. The spacing between dislocations in a (single-phase) annealed metal with a dislocation density of the order of 106 to 107 cm per cm3 also is of the order of 10-3 cm. Therefore it is not reasonable to expect that the arrangement of the dislocation lines is the same in the composite material as it is in pure indium. If the dislocation arrangements are different the density of the dislocation sources likewise will be different. Another way of saying the same thing is the following. The presence of the glass spheres reduces one of the dimensions of the metal phase to 10-3 cm. Thus the metal phase, in effect, is equivalent to a metal whisker or a thin metal film. These are strong because they have so few dislocation sources within them. T. D. Gulden and J. C. Shyne (authors&apos; reply)—It is to be expected that the arrangement of dislocations in the indium-glass composites would be quite different than that observed in annealed pure metals. The dislocations probably exist primarily as segments connecting the dispersed particles. These segments and discontinuities at the very large area of particle-metal interface could act as dislocation sources. For this reason it was considered unlikely that the very high observed creep strengths were due to a low density of dislocation sources. A more likely explanation is that the distance a dislocation can glide is limited by the interparticle spacing. The particles averaged about twenty in diam and were less than 10 µ apart in the 40 pet composite. It seems reasonable to assume that a dislocation loop in a volume of metal surrounded by these relatively large particles would not bow out around them but would be restricted to the region between particles. A general expression for creep rate is given by the product of the dislocation source density, the average rate at which loops are generated from a source, and the average area swept out by a loop times the Burgers vector magnitude. Assuming that the area swept out is limited by the interparticle spacing and the rate of generation of loops is controlled by the rate of climb of loops over second-phase particles, as suggested by Ansel and Weert-men,9 a calculation of the dislocation source density may be made from the experimentally observed creep rates. The result comes out 10" to 10" per cm3 which seems reasonable in view of the assumptions involved. Thus it is concluded that the anomalously low creep rates that were observed were due not to a low dislocation source density but rather to a limitation on the area swept out by each dislocation loop.

Jan 1, 1964

By Sherwin F. Kelly

One of the most succinct and illuminating perspectives of the field of geophysical exploration to appear in recent years is an article by E. A. Eckhardt, in the magazine Geophysics for October 1949. Although his review covers the year 1948, many of the data presented are apropos to a review of 1949, and form a pertinent background for a consideration of current progress. He presents charts of the world-wide distribution of gravimeter and seismograph activity in oil exploration, which show that surveys in the United States accounted for practically 68%; of all gravity work and 80%; of all seismic activity. Canada ranked second, with a proportion of roughly 6%, in each case; South America accounted for about the same percentage of seismic work, and double that amount for gravity surveys. Within the United States, Texas and Louisiana were the scenes of the greatest activity, both claiming about 60% of all surveys by each method.

Jan 1, 1950