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By W. Luyken

A NUMBER of articles have been published, notably those by R. S. Handy, R. T. Hancock and A. P. Watt in Engineering and Mining Journal, dealing with the calculations involved in ore dressing.. These publications demonstrate both, the importance of the subject and the lack of success in developing a generally recognized method for comparing enrichment effects. Considering that we may wish -to compare enrichment results on similar or dissimilar ores, that we may desire to make the comparison on the basis of either the absolute or the economical efficiency, and that the number of factors upon which the result depends is large, the question arises whether it is possible to set up a positive method for such calculations. In the following pages it is our aim to show that a sure, complete and successful way to overcome existing difficulties has been found. GRAPHICAL ANALYSIS OF ORE-DRESSING PROCESSES The following is from Truscott's Text Book of Ore Dressing (London, 1923) x = assay of ore treated (feed). y = assay value of the concentrate. z = assay value of the tailing. a = weight of feed. b = weight of concentrate. c = weight of tailing. C = fractional concentration = b/a= x-z/y-z (1) K = ratio of concentration = 1/C = a/b =y-z/x-z (2) R = fractional recovery = yb/xa = Cy/x. (3) 100R = percentage recovery. Copt = theoretically best concentration. 100 - Copt = waste in the feed.

Jan 1, 1929

By Leonard A. Wood, A. G. Winslow

Subsidence has occurred in several areas of the upper Gulf Coast region of Texas, although in most cases this is not evident without precise instrumental leveling. As referred to in this report, the region com- prises about 7200 sq miles of the Gulf Coastal Plain and includes all or parts of the following counties: Harris, Fort Bend, Waller, Brazoria, Galveston, Liberty, Chambers, Orange, and Jefferson (Fig. 1 ). Topographic relief is low, ranging from sea level at the Gulf of Mexico to 300 ft or more in northwestern Harris County.

Jan 10, 1959

By J. W. Marx

A method is given for predicting the complete gravity drainage characteristics of arbitrarily long columns from centrifuge drainage measurements on reconstituted core samples. Oil residuals corresponding to hundreds of years of normal gravity depletion can be obtained in a few hours on the centrifuge. The gravity flow rate at any stage of the depletion process may be determined from the time correlation derived, and experimentally checked, in this study. INTRODUCTION Apart from the original observations of Muskat et al1, research publications2,3,4 on the subject of gravity drainage have been largely concerned with establishing in detail the saturation, S as a function of the height, z, in a draining column at any given time, t. Some form of numerical integration must be employed to obtain production rates and cumulative production even when S(z, t) is known. Furthermore, the relevant experimental work has been concentrated on drainage of a single wetting liquid from unconsolidated media. Since oil production usually concerns the drainage of a partially wetting liquid from consolidated media, in the presence of connate water, and since it is unlikely that sufficient information exists to establish S(z, t) in detail for any natural reservoir, the published research work appears to be, at best, only qualitatively applicable to production problems. With this in mind, the present study was undertaken by the writer. Experiments were planned whose results would have two advantages over existing measurements: 1. Observations were to be made on specific reservoir rock, reconstituted with formation water and formation oil. This would reduce their generality, from the research viewpoint, but increase their utility for production purposes. 2. The measurements were to be self-integrating, i.e., the phenomena were to be described and interpreted in terms of cumulative results. THEORETICAL DEVELOPMENT It was commonly known that centrifuging a liquid bearing porous medium increases the drainage rates and minimizes capillary end effects. The specific problem lay in selecting an acceleration, a, such that the mean residual saturation of a model cylinder was equal to the residual saturation of an arbitrarily long prototype column when the latter was drained by earth gravity alone. The physical conditions required to permit a valid scaling of model drainage time, tm with prototype drainage time, t, may be stated as follows: (a) At t = tm = O, So = Smo; (b) At t = tm? 8 Sr. = Smr.; (c) For all intermediate values of t and dS/dt=dsm/dtm whenever S = Sm; (d) S(z) = Sm(z) = a constant when t = tm = 0. 1 Here S = T I S(z)dz, where h is the length of the « Jo cylindrical column being drained and the subscripts S,Sm, and refer to model, initial, and residual systems, respectively. The first three conditions mean, simply, that an 3 vs t plot will be numerically identical with an S, vs t, plot,

Jan 1, 1957

By Molly Gleiser, John Chipman

The standard free energy of formation of WC was obtained from determination of the equilibrium WC + CO2 = W + 2CO between 1215° and 1266°K. Its uallie is -8340 * 300 cal Per mole over the above range of temperature. AS a part of a program devoted to measuring the stabilities of the carbides, a study was made of the free energy of formation of tungsten carbide, WC. The homogeneity range of this compound is very small,' and it is generally accepted and is dealt with here as a stoichiometric compound. The heat of formation, ?H°f, of WC has been accurately measured by Huff, Squitieri, and snyder.2 The only attempt, however, to measure the free energy of formation of this compound was made by Schenck, Kurzen, and wesselkock3 who brought tungsten carbides into equilibrium with H2 and CH4. Unfortunately their results are not sufficiently accurate nor consistent enough to permit the calculation of free energies. METHOD Heating mixtures of tungsten and carbon powders in hydrogen for 4 days at 1050°C led to formation of some WC without any trace of W2C. It was deduced, therefore, that at least below this temperature W2C will not be formed during experiments with mixtures of tungsten and WC. This was subsequently shown to be correct. The method chosen was the measurement of the equilibrium of the reaction

Jan 1, 1962

By J. F. Havard

Gypsum is a useful industrial mineral found abundantly on the earth's crust. It is inexpensive to mine and process, and its calcined products have a wide range of readily controllable properties such as strength, density and setting time. It has proven to be such a useful material indeed, that ten American companies, operating some 57 calcining plants in 25 states in 1958, produced or imported in that year a total of 13,649,000 tons of the crude mineral valued at $39,361,000, which they then converted into manufactured products with a value of $329,070,000. Gypsum (CaSO4.2H2O) is calcium sulfate with two molecules of combined water, which are responsible for most of its useful properties. It is closely associated in most deposits with anhydrite (CaSO4), which contains no combined water and has limited commercial value in the United States. Man has long recognized the useful qualities of gypsum. It was utilized by the Egyptians in the construction of the pyramids and, later, by the Romans for important structures. Many of the ancient peoples prized gypsum for artistic and ornamental purposes, carving statuary from alabaster and making casts with plaster. The tabular variety, selenite, was used for windows, and the light transmitted through these windows reminded people of light from the moon (selene), hence the name selenite. The use of gypsum continued through the Middle Ages and into modem times. Benjamin Franklin was a famed exponent of gypsum because he applied ground gypsum to clover fields in the form of large letters which later read, in the more luxuriant growth, "land plaster used here." Gypsum is still used as an effective conditioner for some soils, but in recent decades, particularly in North America and Europe, it has become much more important as a major material for the building industry. Description Gypsum and anhydrite are closely associated minerals. Gypsum is found in a number of forms: massive rock gypsum, alabaster, selenite, satin spar, and gypsite. Anhydrite is found as massive rock or as smaller bodies or isolated crystals included in gypsum. Massive Rock Gypsum comprises most of the commercial gypsum and occurs as a sedimentary rock, interbedded in most places with shale, limestone or dolomite. This rock is soft and crystalline. Its color is white or shades of gray, pink, yellow, brown or other colors. Alabaster is a pure, compact and fine-grained variety suitable for use in sculpture or turning into artistic forms; it may be white or selected for attractive coloration. Selenite is gypsum crystallized in flat, transparent, flexible foliated plates, found in clays or in surface vugs in gypsum. Satin Spar is a fine silky fibrous variety with the axes of the crystalline fibers perpendicular to the vein or joint in which it has formed. Gypsite is an earthy mixture of gypsum with clay and sand in secondary formations; it is sometimes useful as a soil conditioner and has been used in making base-coat plasters. Pure gypsum contains 20.9 pct combined water, 46.6 pct sulfur trioxide (SO3) and 32.5 pct lime (CaO). Standard specifications (American Society for Testing Materials Designation C 22-50) read that minimum purity for material to be called gypsum is 70 pct CaSO4.2H20. Most of the commercial gypsum is 85 to 95 pct pure as produced. Impurities in

Jan 1, 1960

By Lane Mitchell

A ceramic product or processed material is a solid composed of materials which have been subjected to heat above 875°F. The raw materials, which are blended together (or in some cases used singly), are selected and utilized for various reasons such as ease of fabrication, aid to processing, to yield desired properties after processing, lack or controllable degree of toxicity or hazard, availability, cost, and perhaps other considerations. Almost all solid inorganic, some organic, and some liquid and gaseous materials have the potential to be used individually in some ceramic product. There are several fundamental functions to be fulfilled in every ceramic product and a number of secondary functions are desirable in specified products. These functions are generally met by the most widely occurring minerals and rocks of the earth and their debris. This fact characterizes ceramics as a field utilizing the raw materials most available to man. Of course, specified products utilize synthetics, organics, and rare inorganics to produce desired results. Any solid nonmetallic product processed by subjection to temperature above a red heat may be called a ceramic product. Widely used construction materials and units, domestic utensils and units, industrial parts to facilitate manufacture, technical components, and aesthetic creations are very often of a ceramic nature because of the durability, inertness, hardness, ease of fabrication, cost, and availability of the ingredients. Often, organics or metals cannot meet desired specifications for some of these products. The rocks and minerals and mineral debris of the earth are largely siliceous. Oxygen and silicon comprise roughly 75% of the earth's crust with aluminum, iron, calcium, and the alkalies following in abundance. Silica ( SiO, ) and silicates can be melted to form glasses. Alumina (A1,0,), present in a mineral com- pound, gives greater durability, hardness, and strength, but lessens the glass-forming property. Iron, calcium, and the other alkalies flux silica and reduce melting points. Thus, sand, which is generally almost pure SiO,, and clay, which is generally hydrated alumina silicate, are the most widely used of all ceramic raw materials-principally because of the glass-forming propensities of silicates. In ceramic formulations, clay is generally a refractory filler or skeletal material, having in the raw state a plasticity derived from its colloidal grain size and its water-loving nature. On the other hand, silica sand is a glass former or nonplastic filler. Clay and silica sand in pure forms are quite refractory, i.e., not easily melted. Clay, although siliceous, is less of a glass former than pure silica and is more refractory. Natural contaminants, such as iron oxide or limestone, adulterate many clays and some sands. These contaminants act as fluxes and reduce the fusion points of the mineral or blends. Glass is made from silica sand by fluxing the sand with strong bases, usually soda ash and limestone. Red building bricks are hard and durable because the sand and clay have been partially fused with help of natural iron oxide serving as a flux. The iron oxide per- forms a dual function, serving as a pigment as well as a flux. In a blend of clay and sand and iron oxide, the sand is more susceptible to fusion than is the clay. Although silica sand and clay are the most widely used raw materials in most ceramic products, many other minerals, and some non- minerals are utilized in products where these materials can produce or aid in achieving desired results. Limestone and dolomite, feldspars, pigmentary minerals, refractory oxides or carbides, and special property producers can

Jan 1, 1975

By Lane Mitchell

A ceramic product or processed material is a solid composed of materials which have been subjected to heat above 468.3°C (875°F). The raw materials, which are blended together (or in some cases used singly), are selected and utilized for various reasons such as ease of fabrication, aid to processing, to yield desired properties after processing, lack or controllable degree of toxicity or hazard, availability, cost, and perhaps other considerations. Almost all solid inorganic, some organic, and some liquid and gaseous materials have the potential to be used individually in some ceramic product. There are several fundamental functions to be fulfilled in every ceramic product and a number of secondary functions are desirable in specified products. These functions are generally met by the most widely occurring minerals and rocks of the earth and their debris. This fact characterizes ceramics as a field utilizing the raw materials most available to man. Of course, specified products utilize synthetics, organics, and rare inorganics to produce desired results. Any solid nonmetallic product processed by subjection to temperature above a red heat may be called a ceramic product. Widely used construction materials and units, domestic utensils and units, industrial parts to facilitate manufacture, technical components, and aesthetic creations are very often of a ceramic nature because of their durability, inertness, hardness, ease of fabrication, cost, and availability of the ingredients. Often, organics or metals cannot meet desired specifications for some of these products. The rocks and minerals and mineral debris of the earth are largely siliceous. Oxygen and silicon comprise roughly 75% of the earth's crust with aluminum, iron, calcium, and the alkalies following in abundance. Silica (SiO2) and silicates can be melted to form glasses. Alumina (A1203), present in a mineral compound, gives greater durability, hardness, and strength, but lessens the glass-forming property. Iron, calcium, and the other alkalies flux silica and reduce melting points. Thus sand, which is generally almost pure SiO2, and clay, which is generally hydrated alumina silicate, are the most widely used of all ceramic raw materials-principally because of the glass-forming propensities of silicates. In ceramic formulations, clay is generally a refractory filler or skeletal material, having in the raw state a plasticity derived from its colloidal grain size and its water-loving nature. On the other hand, silica sand is a glass former or nonplastic filler. Clay and silica sand in pure forms are quite refractory, i.e., not easily melted. Clay, although siliceous, is less of a glass former than pure silica and is more refractory. Natural contaminants, such as iron oxide or limestone, adulterate many clays and some sands. These contaminants act as fluxes and reduce the fusion points of the mineral or blends. Glass is made from silica sand by fluxing the sand with strong bases, usually soda ash and limestone. Red building bricks are hard and durable because the sand and clay have been partially fused with help of natural iron oxide serving as a flux. The iron oxide performs a dual function, serving as a pigment as well as a flux. In a blend of clay and sand and iron oxide, the sand is more susceptible to fusion than is the clay. Although silica sand and clay are the most widely used raw materials in most ceramic products, many other minerals, and some nonminerals are utilized in products where these materials can produce or aid in achieving desired results. Limestone and dolomite, feldspars, pigmentary minerals, refractory oxides or carbides, and special property producers can

Jan 1, 1983

By S. C. Sun

With the aid of emulsifiers, intense high-frequency sound waves are capable of emulsifying any collector in water. The data show also that ultrasonically emulsified collectors are more effective in floating minerals than the nonemulsified collectors. THE use of ultrasonics in forming emulsions is not new. As early as 1927 Wood and Loomis reported preparation of emulsions with ultrasonics. In 1935 Rschevkin and OstrawskyV escribed the use of great ultrasonic power in producing fine emulsions of various oils and paraffin in water. Recently Oyama and Tanaka3 employed ultra-emulsification to increase the effectiveness of sodium ethyl xanthate in flotation of chalcopyrite and galena. An emulsion is a two-phase system consisting of two incompletely miscible liquids, the one being dispersed as finite droplets In the other. The dispersed liquld is known as the internal or discontinuous phase, and the surrounding liquid is termed the external or continuous phase. There are two types of emulsions; one is oil-in-water (O/W) and the other water-in-oil (W/O). The word oil refers to the liquid other than water. Circumstances exist in which the emulsion type is not clearly defined, and the internal and external phases both contain portions of the opposite phase. This is said to be a dual emulsion. Among the many hypotheses, 5a, B proposed for the formation of emulsions, the Bancroft's adsorbed film or double interfacial tension theory is widely accepted. Bancroft 7, 8 deduced that in the process of emulsification the interfacial tension between oil and water is lowered by the formation of an emulsifying film, which contains the adsorbed molecules and/or ions from the emulsifying agent and the two liquids. This film has two interfacial tensions, one with the water and the other with the oil, which are not necessarily equal. The difference in interfacial tension between the two surfaces of the film is chiefly responsible for forming different types of emulsions. For example, if the interfacial tension between water and film is less than that between oil and film, the film will become convex on the water side, thereby tending to form an oil-in-water emulsion. On the other hand, if the interfacial tension between water and film is greater than that between oil and film, the film will become concave on the water side, thereby tending to make a water-in-oil emulsion. In line with this theory, emulsifying agents soluble in water have the tendency to form oil-in-water emulsions, while those soluble in oil form emulsions of the reverse type. Apparatus and Experimental Procedure: The ultrasonic apparatus shown in Fig. 1 consisted of a hypersonic generator (A), Brush Development Co. model Bu-204; a hypersonic transducer bowl (B) whose resonant frequency is 400 kc per sec; and a round-bottomed glass tube (C) of 2.2 cm ID and 21 cm in length. The acoustical output power of the hypersonic transducer bowl was standardized with a Hewlett Packard vacuum tube voltmeter, model 41 0B, across the hypersonic generator output. The glass tube, containing the materials to be emulsified, was placed 1 cm above the central surface of the transducer bowl, which was filled with water as shown in Fig. 2. Ultrasonic emulsification was performed in three steps, although a one-step method has been used: 1) emulsifying the predetermined amounts of col-

Jan 1, 1956

By AIME AIME

SOME 65 members of the Institute, including most of the Local Section delegates and several Directors and officers, were on hand for the Annual Business Meeting of the Institute held in the Engineering Societies Building on Monday, Feb. 21, at 4:30 p.m., immediately following the second session of the Local Section Delegates Conference. President Mathewson presided. The meeting was largely taken up with the presentation of committee re- ports, discussion of which was invited. F. E. Wormser presented the report of the Admissions Committee ; Philip Kraft, Papers and Publications Com-

Jan 1, 1944

By H. J. Hager, P. H. Haskell

For the past 20 years Alabama has probably led all other coal-producing districts in the proportion of coal prepared by wet washing. All rail mines, with one exception, and a high percentage of truck mines now wash all coal under 3 or 4 in. Most of this coal has been cleaned by jigs, though within the past few years one or more wet-table plants have been installed for cleaning some of the coal from practically all the major seams. These tables supplement either single or multicell jigs usually for one of the following purposes: (I) to wash the finer sizes of raw coal, (2) to rewash the finer sizes of washed coal after they leave the jigs, (3) to re-treat jig middling products. The main purpose of this paper is to present cleaning data and operating factors involved in the preparation by tables of the finer sizes of raw coal. The specific information and data pertain to the Mary Lee seam of coal as extracted at three of the mines of the Alabama By-Products Corporation, which produces coal for both byproduct coke-oven consumption and the general steam market. The Mary Lee seam has long been recognized by coal-preparation authorities as presenting a very difficult ash-reduction problem. Washing characteristics and physical structure of the seam vary widely. Its thickness ranges from 32 in. with no rock parting to 100 in. with from one to three partings. Over the entire field the bed contains bands of bone and rash. These are distributed throughout the seam cross section. A portion of this bone or bony coal occurs as definite bands I in. or more thick; however, some bone is interlocked as layers within the coal and consequently breaks into flakes when the coal is broken. This material is relatively high in ash and its specific gravity varies widely. It has been observed that in most cases in the washing of Mary Lee coal from 10 to 18 per cent of the raw coal is within +0.10 specific gravity of the attempted point of separation. Therefore with the average wet jig, only with extreme difficulty can a low-ash product be obtained without loss of much marketable coal in the refuse. Without entering into the controversial question as to whether modern washing equipment can efficiently handle simultaneously all sizes up to a given maximum, suffice it to state that the comparatively old-type jigs in service at the Alabama By-Products Corporation's mines could not clean the he sizes satisfactorily. Therefore, in 1931 that company installed six diagonal-deck tables at the Barney mine, which were installed as an addition to a complete plant cleaning all coal below minus 3 in. The primary washed product is shipped as steam coal and another portion may be prepared as washed nut for domestic trade. These tables are washing 9 tons per hour of raw coal sized to ¼ in. to o. The washed table coal is mixed with the 3 to ¼-in. jig product to constitute a 3 in. to o steam coal.

Jan 1, 1942

By H. J. Hager, P. H. Haskell

For the past 20 years Alabama has probably led all other coal-producing districts in the proportion of coal prepared by wet washing. All rail mines, with one exception, and a high percentage of truck mines now wash all coal under 3 or 4 in. Most of this coal has been cleaned by jigs, though within the past few years one or more wet-table plants have been installed for cleaning some of the coal from practically all the major seams. These tables supplement either single or multicell jigs usually for one of the following purposes: (I) to wash the finer sizes of raw coal, (2) to rewash the finer sizes of washed coal after they leave the jigs, (3) to re-treat jig middling products. The main purpose of this paper is to present cleaning data and operating factors involved in the preparation by tables of the finer sizes of raw coal. The specific information and data pertain to the Mary Lee seam of coal as extracted at three of the mines of the Alabama By-Products Corporation, which produces coal for both byproduct coke-oven consumption and the general steam market. The Mary Lee seam has long been recognized by coal-preparation authorities as presenting a very difficult ash-reduction problem. Washing characteristics and physical structure of the seam vary widely. Its thickness ranges from 32 in. with no rock parting to 100 in. with from one to three partings. Over the entire field the bed contains bands of bone and rash. These are distributed throughout the seam cross section. A portion of this bone or bony coal occurs as definite bands I in. or more thick; however, some bone is interlocked as layers within the coal and consequently breaks into flakes when the coal is broken. This material is relatively high in ash and its specific gravity varies widely. It has been observed that in most cases in the washing of Mary Lee coal from 10 to 18 per cent of the raw coal is within +0.10 specific gravity of the attempted point of separation. Therefore with the average wet jig, only with extreme difficulty can a low-ash product be obtained without loss of much marketable coal in the refuse. Without entering into the controversial question as to whether modern washing equipment can efficiently handle simultaneously all sizes up to a given maximum, suffice it to state that the comparatively old-type jigs in service at the Alabama By-Products Corporation's mines could not clean the he sizes satisfactorily. Therefore, in 1931 that company installed six diagonal-deck tables at the Barney mine, which were installed as an addition to a complete plant cleaning all coal below minus 3 in. The primary washed product is shipped as steam coal and another portion may be prepared as washed nut for domestic trade. These tables are washing 9 tons per hour of raw coal sized to ¼ in. to o. The washed table coal is mixed with the 3 to ¼-in. jig product to constitute a 3 in. to o steam coal.

Jan 1, 1942

By Arthur W. Ruff

One of the major challenges to management in the mining industry today is the establishment and maintenance of positive and dynamic programs for cost control and cost reduction. To meet the challenge, management must have a good cost system. There are various types of cost accounting systems in use today: some companies check their, performance by comparing the costs incurred during one period with the costs incurred during previous periods, while others compare the current costs with estimated costs which the company considers desirable. A third type of system is a standard cost system which provides predetermined allowances for the various cost elements and operating activities. Such a system, based on sound standards, can be established to fix responsibility for cost performance in each segment of the operation; recognize the impact of volume or rate of activity by establishing a standard volume and evaluating departures: take into consideration fixed and variable costs and their dissimilar behaviour at varying levels of operations: and provide consistent and equitable yardsticks for measuring performance.

Jan 11, 1962

By G. K. Burgess

THE question of the allotropy of iron, in spite of a vast amount of experimental work and perhaps an even greater amount of theorizing, is not yet settled. That there is a definite transformation in iron near 900,° the A3 point, is generally recognized, as well as the fact that the temperature of this transformation is lowered by the addition of carbon and metallic elements. On heating, the transformation Ac3 is always found at a higher temperature than the transformation on cooling, Ar3. Whether the A3 transformation is sharp like the melting point of a pure substance, or extends over a considerable range of temperatures, embracing perhaps as a lower limit the A2 change, appears to be still an open question for pure iron. The nature and identity of the A2 transformation, it would appear from recent publications, has not yet been satisfactorily settled. In the present paper a critical, historical summary is given of the experimental investigations of the location of A2 and A.3 in pure iron, together with brief mention of some of the theoretical aspects of the subject, and an account is given of a series ?of experiments carried out with several samples of very pure iron which were studied by two methods of thermal analysis in the range from 5000 C. to 1,000° C., and which it is believed furnish a contribution of considerable interest as to the location and nature of the A3 and A2 transformations. Great attention has been given to the details of experimental manipulation and to the preparation of the samples, as it was soon found that some of the discrepancies noted in the work of many experimenters may be traced largely to lack of precautions which we have found essential. For example, to anticipate somewhat, it is necessary to provide a suitable practically gas-free furnace, the heating and cooling of which may be regulated to a nicety. To render a minimum the deforming effects on the cooling and heating curves of the poor conduction of the sample, it must be of a form and mass to pass on its heat rapidly and completely to the thermocouple; and finally the sample itself must be freed from gases which, if present, further mask the definiteness of the heating and cooling curves. We, have also varied within wide limits the several factors which may influence the determination of the exact location and shape of the transformation ranges, especially the mass and preparation of sample, rate of heating and cooling, design of furnace; and finally, as nearly as it is experimentally possible, we have worked with a substance approaching pure iron, free from occluded gases and other impurities, and contained within a vacuum.

Jan 10, 1913

By Byoung Whie Lee

In order to investigate the change in surface energy as a function of cold work ad environment, the contact angles between a liquid and the surface of elec-tropolislzed aluminum with various degrees of cold work were measured. Specinlens cut from aluminum rod (99.99 pct Al) were annealed at 600°C for 24 hr and then cold compressed parallel to the drawing di-rectzon of the rod in increments of approximately 10 pcl from 0 to 70 pct. The sections, taken transversely to the drawing direction, were mechanically and electro chemically polished. Contact angles between the sessile drop of distilled water, glycerin, and glycol and the specimen surface were measured optically. The differences in interfacial energy were calculated from the contact angle data. The effects of chemical washing and surface roughness of the specimen on the contact angle were also studied. The liquid contact angle was a linear function of the degree of cold working (D) ad changed markedly with differed liquids. THE plastic deformation of polycrystalline metals induces a preferred orientation in crystal structure. A preferred orientation changes the atomic density of a metal surface. This change in surface atomic density brings about the changes in surface interactions of the metals."' Also, the plastic deformation of metals raises the internal energy by increasing the stored energy.' Consequently, the total Helmholtz free energy of the metal increases and, in turn, the surface free energy of the metal. In order to study the effect of plastic deformation on solid surface phenomena, the liquid contact angle of a sessile drop made on cold compressed and elec-trochemically polished aluminum was measured. The preferred orientation in aluminum, due to uniaxial compression, is known to be [110] direction parallel to the compression axis. However, this description is only a first approximation of a rather complex orientation. In actuality, half the crystallites are more than 10 deg from this orientation, regardless of the amount of compression." For randomly oriented fcc crystals, the average surface atomic density can be calculated as follows: The number of atoms in a unit volume is 4/a3, where a is a lattice constant. Hence, the number of atoms per unit surface area is about (4/a3)2/3 = 2.52/a2 However, when the preferred orientation took place along [110] direction, the surface atomic density is as follows: The area of (110) plane of a unit cell, considering ridges and valleys, is BYOUNG WHlE LEE, Member AIME, is Research Metallurgist, Atomic Energy Research Institute of the Republic of Korea, Seoul, Korea. Manuscript submitted May 29, 1968. IMD 2 x J2- a x Ga = 6a2 Since this plane contains 4 atoms, the surface atomic density is 4i6a2 = 2.3/a2 Upon changing from random to preferred orientations, the surface atomic density decreases about 10 pct. The increase in the stored energy and the change in surface atomic density due to plastic deformation would certainly alter the surface tension of a metal. EXPERIMENT High purity aluminum rod of 6-mm diam (99.99 pct Al, obtained from Johnson, Matthey & Co., Ltd, London, England) was cut into sections approximately 1 cm long. The transverse cross section was mechanically polished. Then, the specimens were annealed in air at 600°C for 24 hr. Thus, eight annealed specimens were uniaxially compressed at room temperature from 0 to 70 pct of cold working with an increment of 10 pct. The extent of cold working was determined by the percentage of reduction in axial length to the original length. The specimens were further polished mechanically and, then, electrochemically with the Modern Battelle Type 1 electropolishing solution with a current density of 0.3 to 0.4 amp per sq cm and an electrode potential of 8 to 12 v at the solution temperature of 78" to 82°C for approxirr~ately 5 min. The Modern Whlte Diffusing Screen \t/ --------------- re Goniometer for Mercury Lamp ^-^ Sessile Drop ¦=• Condenser c=> Microscope l_*~_i bJ Mlcromster Filer with Protmcter Fig. 1—Schematic diagram of apparatus set-up for liquid contact angle measurement.

Jan 1, 1970

By J. E. Gould, H. J. Hand

Many independent studies are being made on slag-metal relationships in the open-hearth furnace, and these studies cannot help but result in an ultimate improvement in the quality of open-hearth steel of both the open and killed types. In maintaining quality control at the National Tube Company's plant, emphasis has been placed on an evaluation of the iron oxide content of the steel in as quantitative a manner as possible, in order that the most desirable level of oxidation might be obtained for a given type of steel, and to secure a more precise basis for final de-oxidation. In the past, various methods were used for estimating FeO content of the metal at tap to ensure uniform and thorough deoxidation of killed steel, avoiding overdeoxidation to minimize the amount of inclusions present and to make as sound a steel as possible. For the open-type steels, such control involves obtaining the necessary level of oxidation for the most suitable action of the steel in the molds to provide good surface quality and cross section for the specific grade involved. While rapid analytical methods are available for determination of FeO in the liquid metal, such methods are still not sufficiently rapid for routine control on the open-hearth floor, nor do such analyses provide information as to what causes high or low FeO values. The method of sampling can still be considered a problem in view of the variability encountered in taking simultaneous duplicate tests. With the accurate rapid methods now available for determining carbon in the metal, estimating slag basicity and obtaining temperatures of liquid metal, it was believed possible to determine the influence of the various furnace reactions in establishiug the state of oxidation at a given time. Simultaneous slag and metal tests were used in this analysis, aided by statistical methods, to determine the factors that affect the metal FeO, and also to make a quantitative evaluation of these factors. Data obtained are from actual iurnace operations, the metal test being of the I spoon, Herty type, and taken in duplicate. Metal temperatures were taken with the open-tube bath pyrometer developed by the Research Laboratory of the United States I Steel Corporation. This method of taking open-hearth metal temperature was invented by Collins and Oseland,l and was developed into its present form by L. 0. Sordahl,2 of the Research Laboratory. The instrument and its mode of operation have been fully described by Sordahl and Sosman in three publications.3,4,5 lag components were obtained by chemical analysis. Data were taken from four 165-net-ton furnaces during the working period of the heat. Recognizing that additions of ore affect the metal FeO. no tests were included within 30 min. after ore additions. In all, 65 tests (48 heats) were used in this study.

Jan 1, 1942

By J. E. Gould, H. J. Hand

Many independent studies are being made on slag-metal relationships in the open-hearth furnace, and these studies cannot help but result in an ultimate improvement in the quality of open-hearth steel of both the open and killed types. In maintaining quality control at the National Tube Company's plant, emphasis has been placed on an evaluation of the iron oxide content of the steel in as quantitative a manner as possible, in order that the most desirable level of oxidation might be obtained for a given type of steel, and to secure a more precise basis for final de-oxidation. In the past, various methods were used for estimating FeO content of the metal at tap to ensure uniform and thorough deoxidation of killed steel, avoiding overdeoxidation to minimize the amount of inclusions present and to make as sound a steel as possible. For the open-type steels, such control involves obtaining the necessary level of oxidation for the most suitable action of the steel in the molds to provide good surface quality and cross section for the specific grade involved. While rapid analytical methods are available for determination of FeO in the liquid metal, such methods are still not sufficiently rapid for routine control on the open-hearth floor, nor do such analyses provide information as to what causes high or low FeO values. The method of sampling can still be considered a problem in view of the variability encountered in taking simultaneous duplicate tests. With the accurate rapid methods now available for determining carbon in the metal, estimating slag basicity and obtaining temperatures of liquid metal, it was believed possible to determine the influence of the various furnace reactions in establishiug the state of oxidation at a given time. Simultaneous slag and metal tests were used in this analysis, aided by statistical methods, to determine the factors that affect the metal FeO, and also to make a quantitative evaluation of these factors. Data obtained are from actual iurnace operations, the metal test being of the I spoon, Herty type, and taken in duplicate. Metal temperatures were taken with the open-tube bath pyrometer developed by the Research Laboratory of the United States I Steel Corporation. This method of taking open-hearth metal temperature was invented by Collins and Oseland,l and was developed into its present form by L. 0. Sordahl,2 of the Research Laboratory. The instrument and its mode of operation have been fully described by Sordahl and Sosman in three publications.3,4,5 lag components were obtained by chemical analysis. Data were taken from four 165-net-ton furnaces during the working period of the heat. Recognizing that additions of ore affect the metal FeO. no tests were included within 30 min. after ore additions. In all, 65 tests (48 heats) were used in this study.

Jan 1, 1942

By R. I. Jaffee, C. M. Craighead, G. A. Lenning

Hydrogen forms a beta-stabilized system with titanium, with a beta eutectoid at about 300°C and 44 atomic pct H2. 'The solid solubility of hydrogen in alpha decreases from about 8 to about 0.1 atomic pct from 300°C to room temperature. Hydrogen has little effect on tensile properties, but decreases notch-bar toughness to a large degree. This latter effect appears to be the result of increased notch sensitivity. PRIOR to this investigation, only a small amount of information was available on the effect of hydrogen on the mechanical properties of titanium. The effects of the other interstitially soluble elements, carbon, oxygen, and nitrogen, had received detailed study. Jaffee and Campbell1 indicated that hydrogen up to 1 atomic pct did not affect tensile properties deleteriously. Pitler' indicated that 1 atomic pct H, in titanium reduced the impact strength appreciably, but his alloys contained appreciable amounts of oxygen, and it was difficult to attribute the embrittlement entirely to hydrogen. The high temperature portion of the equilibrium diagram for the Ti-H system was established by McQuillan," and his data generally corresponded with the results of Kirschfeld and Sieverts," Gibb and Kruschwitz," Bevington, Martin, and Mathews," and other investigators. The lower concentration limit of the hydride phase varied considerably among investigators, and Gibb and Kruschwitz9 ad shown that small amounts of contaminants in either titanium or hydrogen caused considerable variation in this lower limit. In view of this pronounced effect of contaminants, the extrapolated value of McQuillan's, about 48 atomic pct at the 325°C eutectoid, appeared the most reasonable. McQuillan's lowest experimental value was 54 atomic pct at a temperature of 450 °C. The density of titanium had been shown to decrease with increasing hydrogen content, but discrepancies were noted among the various investigations. The best values indicated that the density was decreased from 4.56 grams per cc at 0.27 atomic pctl to 3.84 grams per cc at 61.3 atomic pct? This investigation was conducted to determine the effects of hydrogen on a titanium, both in high purity and commercially pure metals, and on high purity a titanium alloys. Material and Fabrication The literature indicated that impurities in either the hydrogen or the titanium must be kept to a minimum. For this reason, the initial studies were made with high purity iodide-refined titanium. The vendor's analysis of the iodide titanium and the hydrogen content of the as-fabricated Y4 in. diameter rods are shown in Table I. Two 1 lb ingots were prepared by arc melting under argon in a water-cooled crucible, using a water,cooled tungsten electrode. This equipment has been described.' As-cast Brine11 hardness numbers of 88 and 58 for these ingots were low enough to insure that the high purity of the metal was maintained during arc melting. The ingots were hot forged to % in. diameter rods at 800°C, cleaned by grit blasting, and then cold swaged to Yz in. diameter rods. The rod was then air annealed at 725 "C, ground to remove scale, and cold swaged to Y4 in. diameter (75 pct reduction in area). The material was then annealed for 1 hr in argon at 800°C to develop an equiaxed a grain size of about 0.05 mm. Micro tensile specimens and microimpact specimens were machined from this rod prior to treatment in the Sieverts-type absorption apparatus. Two lots of commercially pure RC-55 titanium were also used in this investigation to determine the effects of hydrogen and the normal impurities on mechanical properties. The commercially pure RC-55 alloy was obtained in the form of % in. diameter rod. The analysis of this material is also given in Table I. The % in. diameter rods were hot swaged

Jan 1, 1955

By M. T. Hepworth, W. B. Sample

HYDROGEN solubility and linear contraction measurements were made at constant temperature on an alloy of titanium of constant oxygen-to-titanium molal ratio but variable hydrogen content. A cylindrical specimen of titanium (0.25 by 1.6 in.) containing 0.75 at. pct 0 and less than 0.03 at. pct N was cast from a master button of iodide process titanium which had been alloyed with titanium dioxide. Four vacuum fusion analyses, which were made along the length of the cylinder after the hydrogen solubility studies were made, revealed a variation of oxygen content of less than 0.02 at. pct. The specimen was introduced into a quartz furnace tube, annealed and outgassedat 1050"~ for about 1 hr, and then held at 800" * 0.5" for about 30 hr, during which latter time experimental data were taken. The leak rate to the furnace chamber was not sufficient to contaminate the specimen during the run as determined by leak-rate studies and vacuum fusion analyses for oxygen and nitrogen before and after the runs. The furnace chamber was attached to a modified Sieverts apparatus used to introduce measured quantities of purified hydrogen to the specimen. A quartz pushrod transmitted changes in length of the specimen to a Chevenard dilatometer. The push-rod passed through a vacuum grease seal to the dilatometer which amplified motion of the rod by a factor of 319. During hydrogen addition, the pushrod did not contact the specimen. Measured quantities of hydrogen were added to the specimen and equilibrium hydrogen pressures recorded as a function of hydrogen content. The solubility data, which appear in Fig. 1, agree well with a separate investigation made with a different apparatus. The solubility limit of the hcp a phase appears as an abrupt discontinuity in slope at 3.4 at. pct H. The solubility plot has been extended as a dashed line at this discontinuity in order to emphasize the discontinuity. The hydrogen content at which bcc P appears is not clearly defined. An arrow indicates solubility data were taken upon hydrogen addition. Upon reaching the arbitrary maximum hydrogen content of the run, the quartz pushrod was pressed against the specimen in order to record the change in length with hydrogen removal. A pressure of about 100 g per sq cm was required to overcome the friction of the vacuum seal in order to obtain reproducible linear contraction data. The contraction ratio ~2/1", change in length divided by original length, was set equal to zero for the maximum hydrogen content. The relative contraction of the specimen was observed upon removal of hydrogen in the following manner. The system was opened to the pumps for a few seconds and an unknown quantity of hydrogen was removed. The system was then isolated from the pumps by closing a stopcock and allowed to return to equilibrium. When the temperature returned to 800°C, the pressure stabilized, and contraction ceased, measurements of contraction and pressure were made. The hydrogen content of the specimen was then deduced by measuring the equilibrium PIydrogen pressure and referring to the solubility plot. Linear contraction was then plotted against interpolated values of atomic percent hydrogen. The justification for this procedure is the established reversibility of the hydrogen equilibrium.' Uniaxial compression was assumed to have no effect on hydrogen pressure. The isothermal linear contraction data are plotted on Fig. 1. An arrow indicates data were taken upon removal of hydrogen. The solubility limits of the two phase a i /3 region can be identified by discontinuities ill slope of the dilatometric plot at 9.1 and 3.4 at. pct H, agreeing well with other studies.' Dashed extensions of the plots emphasize the discontinuities. Isothermal studies of expansion made upon hydrogen addition gave curves of much smaller slope and less pronounced discontinuities. A uniaxial compressive stress tends to accentuate volume changes in going from the more open bcc phase to the hcp phase.2 Incomplete data on ex-

Jan 1, 1962

By J. Spreadborough, D. LaW. King, E. Anderson

Tmzsile tests were performed on Armco iron samples, at various ternpe.ralures and strain rates, ocer a wide range of grain sizes. Analysis of the data suggests that the plot of the lower yield stress, against d-1/2,where 2d is the acerage grain diameter, is not linear (as is often assumed) but is concave toward the d. axis over the range of d-from 7 to 53 . The different values of the parameters obtained by other workers can be explained, in part at least, by the observed curvature. This curvalure is shown to be consistent with a model of yielding based on dislocation pile-ups; however, the values of obtained by fitting our data to this model differ appreciably from the values generally reported. The equation proposed by Cottrell, viz.: is a plausible empirical fit to the experimental results. The purpose of this paper is to comment on the validity of the widely used linear relationship first proposed by all' and Petch and coworkers2"4 between ay, the lower yield stress, and 2d, the average grain diameter, for bcc metals, viz.: Many workers, see Refs. 2 to 7 and Table 11, have fitted this equation to their experimental results and have obtained acceptable fits over the relatively narrow range of grain sizes used by most of them. Indeed, in some cases, so few data points were available that any more sophisticated fit would have been irrational. In most of the interpretations,'-' oi is thought to be a measure of the friction stress accompanying dislocation movement, and ky was originally inter- preted as a measure of the dislocation locking but is now believed by Cottrell" to be a function of the dislocation creation rate. In the "unpinning" theories, k, is equated to where od is the unpinning stress and 1 is the average distance from the boundary of the grain where yielding is taking place to the nearest dislocation source in an unyielded grain. Other considerations (see, for example, Refs. 11 and 12) lead to equations with a similar form to [I] where different meanings may be attributed to the parameters. While there are doubts as to the physical significance of the parameters i and k, they continue to be used by many workers; interpretations of the variations in the behavior of ferrite materials following certain treatments, e.g., aging,'3 neutron irradiation,14 have been given frequently in terms of these parameters. Some theories of the mechanical behavior of bcc metals are based on this relationship. We have investigated experimentally the oy - d-'lZ relationship for Armco iron over a wider range of grain sizes and with more data points than those given in published results. The analysis of our data suggests that the oy—d-'" relationship is not linear but is in fact concave towards the d-'I2 axis. RESULTS AND DISCUSSION The experimental work was carried out on 3-mm-diam Armco iron rods which were prepared by wire drawing from 5-mm-diam rods. By annealing in vacuum at temperatures between 7000 and 1200°C for various times, grain sizes from 7 to 20,000 grains per sq mm were obtained, the grains in all cases being regularly shaped. Grain sizes were measured by lineal interceptand by area methods; only specimens with Amax/A values of 3 to 6 were used in the Petch-Hall plots (where A is the average area of a grain and Amax is the area of the largest grain observed). For all the specimens used, the number of grains in a cross section exceeded 50, which should be adequate to avoid grain size effects.'= Tensile tests were performed at 296", 219, and 17l°K, using

Jan 1, 1969

By J. M. Camp

In conforniity with the design of the oficials of the United States Steel Corporation for the standardization of the methods employed in the sampling and analysis of all materials encountered in their various lines of manufacture, the Chemists' Committee presents this compilatioti of standard methods for the sampling and subsequent analysis of molten pig-iron. In selecting the methods, the Committee employed the same line of procedure as in former cases, viz., the careful consideration of all the methods employed in each laboratory of the Corporation, evolving therefrom the several methods herein described, the immediate adoption of which is desired. The services of Messrs. W. B. N. Hawk, William Brady, and C. H. Rich, a sub-committee appointed for the preparation of the present paper, are gratefully acknowledged. II. Introduction. A quite obvious cause of nonconformity of results of comparative analyses in the various laboratories of the Corporation has been an apparent lack of uniformity of method in the sampling and analysis of molten iron. This condition is particularly apparent with regard to the determination of the sulphur, numerous discrepancies in which would appear t.o indicate the absence of, and the necessity for, some uniform method of procedure. The estimation of the

Jan 1, 1913