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By J. D. Lubahn, R. P. Carreker, J. G. Leschen

THE formation of slip bands in crystalline solids undergoing plastic deformation has recently been treated as a problem of nucleation and growth.1 A simplified theory was developed and shown to be qualitatively consistent with certain experimental observations reported in the literature, such as the frequent failure of slip bands to traverse the entire crystal, the effect of specimen diameter and temperature on the yield stress, and the occurrence of incubation periods in the deformation of suddenly loaded crystals. The theory further predicts the appearance of transients in the rate of strain of a crystal when the applied stress is suddenly changed from one constant value to another. A transient consists of a discontinuous change in the strain rate followed by a gradual approach to a steady-state value. Such transient behavior apparently has not been recognized in previous experimental work. The preliminary experiments reported in the present paper were undertaken to confirm the existence of the predicted transients and thus to determine whether a more detailed treatment of the nucleation theory of slip might be theoretically and experimentally fruitful. EXPERIMENTAL PROCEDURE A simple creep apparatus was assembled as shown in Fig 1. Very little insulation was used on the furnace in order to facilitate rapid changes of temperature. Temperature was measured with a thermometer placed in the center of the furnace and was [ ] controlled by adjusting the Variac setting. The specimens were cold-headed in split-cylinder grips. The strain was measured as total elongation by a dial gauge sensitive to 1/10,000-in. movement of the weight pan. Since the specimen gauge lengths were

Jan 1, 1948

By E. T. Dumble

The domes of the Texas coastal plain are structural features, consisting of bosses or stocks of salt, gypsum or anhydrite, or of combinations of these, intruding into and occurring in connection with broken and uplifted sedimentary beds of Cretaceous and Tertiary age. Some of these domes show on the surface as mounds of greater or less elevation, while others are only known from drilling records. They may be divided into two classes: interior domes and coastal domes. The interior domes include those which occur in a zone 40 to 50 miles in width lying immediately east of the Cretaceous-Tertiary contact, and extending from the Sabine to the Colorado. With a single exception, these domes, so far as now known, occur in approximate alignment with the contact, but at irregular intervals. East of the Brazos, the domes are entirely surrounded by Eocene sediments. The coastal domes are found nearer the Gulf, lying entirely within Neocene territory and stretching from the Rio Grande to the Sabine. They are much more numerous than the interior domes, and, apparently, are ranged along several lines having a general northeast-southwest direction. No domes are known in the Oligocene belt. INTERIOR DOMES The interior domes so far, identified are Butler's, in Leon county, Palestine and Keechi in Anderson county, Brooks and Steen in Smith county, and Grand Saline in Van Zandt. In connection with these interior domes we must also consider the Sabine Peninsula,. of Harris, which is, without question, genetically connected with them. The Palestine and Keechi domes have been described recently by 0. B. Hopkins,1 who gives a clear idea of their corn position and structure. Others have been described at different times, and an excellent resume of the literature is given by De Golyer.2 _

Jan 10, 1918

By James M. Townsend

INTRODUCTION The first stage in planning any mining venture is to determine whether the reserves are of sufficient quantity and quality to warrant commencement of mining activities. In addition to total reserve values a modern mining operation requires information on possible support problems, various pillar sizes, and an estimate on recoverable reserves. To achieve this goal in U. S. coal mines, up-to-date computer methods have been applied to existing ground control technology to provide the mining engineer with a reasonably accurate method of determining such figures. The purpose of this paper is to present a mine planning suite comprised of three computer programs, CONTUR, RESERV-COAL and RAMPLAN, created to accomplish this task. These programs were developed at VPI under the sponsorship of the Office of Coal Research (now Energy Research and Development Administration), and are currently available to the mining industry. A basic assumption in the construction of the CONTUR program is that a coal seam is variable in nature. The data available to the mining engineer comes from randomly spaced points, namely boreholes and sampling points, on outcrops or in adjacent mines. These randomly spaced data points are used in the CONTUR program to estimate numerical values at evenly spaced grid points and to provide approximate contour plans. Given the necessary gridded data, RESERV-COAL calculates raw and clean coal tonnages and then provides breakdown on the quantity of coal within specified ranges of ash, sulfur, BTU and reject. RAMPLAN (Rock Mechanics Applied to Mine Planning) also uses gridded data to calculate mining dimensions and estimate recoverable reserves, thereby

Jan 1, 1977

By R. E. Hook, H. J. Garrett, A. M. Adair

X-ray diffraction and metallographic techniques were employed to examine the impurity phases occurring in as-swaged and recrystallized chromium produced fvom high-purity iodide chromium crystals. Chromium oxides are found to form in a consistent manner associated with the temperature of recrystallization. Microscopically observable second phase particles of Cr203 are observed to form intergranulurly beginning at 1300T. Beginning at 1500°C. Cr30, is formed intergvanulurly, atzd at 1600°C and above Cr30, is also formed in association with migrating grain boundaries. Geometrical traces formed by particles of this high temperature oxide uithin the grains rez)eal the histmy of grain boundary motion. X-ray evidence is presented which suggests the existence of a high temperature form of Cr203. Other impurity phases in addition to the oxides of chromium are also present. THE partitioning Of impurity elements between grain boundary aid lattice sires, either as solutes in solution or as second phases, may exercise an important influence on the mechanical behavior of metals and alloy systems. This partitioning of impurities could have a direct bearing on the iecrys-

Jan 1, 1963

By Charles W. Goodale

The attention of the Institute has been called by Prof. John A. Church* and Mr. W. Lawrence Austin? to the free-milling ores of the Tombstone mines and their treatment, but the silver-bearing man ganese ores of the district have received only a passing notice. As these ores show some interesting peculiarities, and have yielded not less than 750,000 ounces of silver, they are worthy of some study. The Knoxville, Lucky Cuss, Luck Sure, and Wedge mines (named in the order of their importance) are situated along the northern border of the district. They have been the leading producers of this manganese ore, and possess the same general characteristics. Special attention will be given to the Knoxville, as it has been the one most extensively developed. The limestone belt, in which the Knoxville ore bodies occur, has an easterly and westerly trend, is about 1680 feet wide, and rests on granite on the north, the plane of contact being nearly vertical. It is overlain by quartzite, the contact-plane having a dip of 82°. Some mining has been done along these contacts, and a considerable amount of pay ore has been extracted, but development has been very superficial. The ore found along these contact planes contains very little manganese, and differs entirely from the ore in the lime stones. No attempt will he made to assign this limestone country-rock to a particular geological horizon, as no fossils have been found in it. Prof. Blake, in a paper on "The Geology and Veins of Tombstone, Arizona" (Trans., x., 334), speaks of the middle and upper strati-

Jan 1, 1889

By S. A. Lever, R. Hultgren

The solidus is usually the least satisfactorily determined portion of a phase diagram. Cooling curves, which succeed well with the liquidus, show the solidus inaccurately or not at all because of segregation which occurs during freezing. Heating curves of carefully homogenized alloys might be expected to indicate accurately the solidus, but they are seldom used. Dynamic methods involving heating or cooling are never completely satisfactory because of uncertainty as to whether equilibrium is attained. A static method in which the specimen may be allowed hours, days, or even weeks to attain equilibrium is to be preferred. In a static method a solid solution, for example, is first made thoroughly homogeneous, then heated to successively higher temperatures. After sufficient time at each temperature to assure equilibrium, some property is measured which should alter strikingly when melting begins. Microscopic examination can be used to detect the beginning of melting, but the method is tedious since the specimen must be quenched, sectioned, polished, and etched before each examination. Of all the physical properties which change on melting, electrical resistance is probably the most satisfactory to measure. The measurement may be made while the specimen is at temperature without damage to the specimen. It may be repeated indefinitely to ascertain when equilibrium has been achieved. Measurements may be made on a single specimen over the whole range of temperature. Most metals approximately double their resistance on melting. Since an accuracy of a few tenths of a percent is easy to achieve, the method is highly sensitive to the beginning of melting. In spite of these advantages, which have been perceived for a long time,l,2 a reasonable search of the literature has failed to reveal a single case in which the method has been satisfactorily applied in practice to the determination of solidus temperatures. The use of electrical resistance measurements appears to have been confined in practice to changes in the solid state. In the work described in the following pages we have applied the electrical resistance method to the solidus of the lead-tin system. We have found the method to be convenient, reproducible, and highly sensitive. We chose the lead-tin system because it leads to few technical difficulties. Furthermore, a number of determinations of solidus have been made in this system by various methods and results could be checked against them. However, all published results are not in good agreement with one another, so this work should help in determining the solidus more precisely. The Lead-tin Diagram Because of its commercial importance, there have been numerous investigations of the lead-tin diagram. The results of the most recent work on the solidus are indicated in Fig 7, as well as the results of the present work. The works of Honda and Abe3 and of Stockdale4 agree fairly well with each other and with the present work. Jeffery's5 data indicate the solidus to be about 50°C lower. Honda and Abe3 used differential thermal analysis on both heating and cooling cycles. Stockdale4 used the microscopic method and also differential heating curves. Stockdale's results were about 4" higher than those of Honda and Abe at low tin contents and lower at higher tin contents. These results also agree with those of Rosen-hain and Tucker.= Jeffery5 used electrical resistance measurements of the alloy as it was being heated or cooled. Apparently he did not attain equilibrium as his results are about 40°C lower than those of Stockdale4 or Honda and Abe.3 MATERIALS AND METHODS The lead and tin used were of high purity. They were supplied by the American Smelting and Refining Co., who gave the following analyses: Lead: silver, 0.0016 oz per ton; copper, 0.0008 pct; cadmium, 0.0007 pct; zinc, 0.0002 pct; arsenic, 0.0003 pct; antimony, 0.0002 pct; bismuth, 0.0005 pct; tin, 0.0001 pct; iron, 0.0020 pct; lead (by difference), 99.995 pct. Tin: antimony, 0.037 pct; arsenic, 0.020 pct; bismuth, 0.004 pct; cadmium, trace; copper, 0.025 pct; iron, 0.004 pct; lead, 0.020 pct; nickel and cobalt, 0.005 pct; silver, 0.0005 pct; sulphur, 0.005 pct; tin (by .-difference). 99.88 pct. One hundred grams of metal with the desired proportions of lead and tin was weighed out to the nearest one-tenth of a milligram. The mixture was placed in a silica crucible, covered with charcoal, and melted in a reducing atmosphere in a gas-fired furnace. The alloy was well stirred. Chemical analysis of two of the alloys checked closely with the weighed portions. The compositions of the remainder of the alloys were taken directly from the weighings, without chemical analysis.

Jan 1, 1950

By John Gross

THE method of measurement of surface on quartz particles was given in a previous paper.1 With such a method the relation of surface produced in crushing quartz can be compared to the work in crushing without recourse to sieve sizing or microscopic measurement. In crushing, the work input must be known with a fair degree of accuracy. With crushers, rolls, ball mills, and similar apparatus the measurement of the work in crushing is subject to possible errors, due to friction in .the transmission as well as in the machine itself. Moreover, relatively large quantities of material must be crushed to get an average figure. In the selection of a method of crushing, simplicity in design and operation was desired and this was most readily obtained by the use of a free-falling body. A description of the apparatus embodying this principle is given herewith. THE CRUSHING DEVICE The apparatus used is shown in Fig. 1 and in cross-section in Fig. 2. The material to be crushed is placed in the crushing chamber C in the steel mortar M. The mortar is 3 in. dia. by 3 in. high. Two mortars are used, one having a crushing chamber 1-in. dia. by 1/2 in. deep, with a capacity of 4 g. of quartz, the other having a crushing chamber 1 ½ in. dia. by 3/4 in. deep, with a capacity of 12 g. of quartz. The position of the mortar is adjusted by means of three centering screws A. The steel plunger P, which fits neatly into the chamber, is placed on top of the material to be crushed. Plungers of different lengths were tried and as they were found to give practically identical results the length adopted was equal to the depth of the chamber.

Jan 1, 1928

By A. R. Powell

Four, general methods have been used in the study of the decomposition of coal. The first has been directed toward the processes of coal formation, the second has been by means of microscopic studies, the third from the data of destructive distillation, and the fourth has made use of various solvents. Applying these methods to the sulfur of coal, it has been found that the organic sulfur of plant and animal life enters into the formation of coal and remains in organic combination in the final product. The inorganic sulfur is almost entirely combined as iron pyrites and marcasite. The infiltration of hydrogen-sulfide waters is doubtless a large factor in these combinations. Sulfates are found in very small quantities except where free oxygen has entered the coal strata. The mechanical mixing of detritus with the early coal material is another source of sulfur. In this case the sulfur is distributed in microscopic particles throughout the mass. In destructive distillation, a part off the sulfur comes off as hydrogen sulfide and various thiophen compounds, but this furnishes little information as to the nature of the sulfur compounds in the coal itself. The use of solvents has given valuable data concerning the sulfur compounds in coal. Fremy1 and later E. Guignet2 noted the action of alkaline solutions on coal after treatment with nitric acid and Anderson and Roberts3 showed' the presence of large quantities of organic' sulfur in the extract so obtained. In a study of the phenol extract of coal, Parr and Hadley4 found organic sulfur in the soluble organic material. These investigations proved the presence of organic sulfur in coal in addition to the inorganic forms, such as iron pyrites and sulfates. T. M. Drown5

Jan 9, 1919

By William G. Schultz

Sylvite’s potash mine probably ranks as one of the most highly mechanized and automated mining operations in the world. Employing, on a normal 10-hr production shift, one supervisor and a crew of seven operators, Sylvite is able to mine at an average rate in excess of 600 tph. The ore is produced by two Marietta miners weighing 258 tons, making them the largest and heaviest piece of equipment ever taken underground. The ore produced by these two Marietta miners is conveyed to the shaft area, cycled through a 15,000 ton storage system and hoisted to surface completely automatically. The operation of all equipment in the mine can be monitored and controlled from a central control panel located underground.

Jan 7, 1972

By J. M. Armstrong

Jan 1, 1934

By E. J. Roberts, E. B. Fitch

THE mechanism of classification by settling pools is most simply shown in the case of batch sedimentation such as was analyzed by Oden.1 The batch model will be considered, therefore, and it will be shown that the same mechanism applies to continuous operation. Classification in Batch Settling Pools: Consider a beaker or tank of slurry containing particles so dispersed that they can settle independently of one another under the influence of gravity. Originally all particle sizes are uniformly distributed throughout the suspension. All particles start immediately to settle towards the bottom at rates determined by their size, shape, and density—among other factors. Particles reaching the bottom settle out of suspension. After some given time the slurry above the deposited solids is siphoned off or otherwise removed, leaving the deposited solids behind. The deposited solids, together with entrained and any unremoved supernatant slurry, represent the underflow of a classifier. The slurry removed represents the overflow. There is a certain separation, size of particle which during the sedimentation has just time to settle from the top surface of the slurry to the level at which underflow and overflow are parted. All particles with a faster settling rate will have dropped to below this level, no matter where in the beaker they started from originally, and therefore will be absent from the overflow. Particles with a slower settling rate will not reach this level if they started from the top of the slurry, but a portion of them,

Jan 1, 1957

By Stanley Herold

As an accompaniment to the interesting papers which discuss the practical aspects of forced drive, or flooding, in our oil fields, and to others which deal with laboratory or field tests on the same subject, a few remarks on the theoretical principles concerned may not be considered inappropriate at the present time. Without claiming to have had the field experience which some of you certainly possess I venture to present some of the results of an analytical investigation upon this method of increasing the recovery of oil from our natural reservoirs. I firmly believe that these results will accord with your experience. I shall confine the present discussion to the consideration of a perfectly ideal situation Let us assume that the productive formation lies perfectly horizontal, that it is of uniform thickness, of perfectly homogeneous texture, and that it contains oil with gas in solution, and no water, throughout a definite, although undefined, lateral extent. We shall furthermore assume that the pressure existing within the reservoir as thus specified, is such that some of the gas is in the free state, spread uniformly throughout, in the form of minute bubbles within the pores of the formation. We now have an ideal reservoir subject to the peculiar action of capillarity as described by the French physicist Jules Jamin. In all directions within the reservoir we see these bubbles of gas, separated by globules of oil which tend to remain in the capillary channels that connect the pores. The action of these bubbles and globules under the application or release of pressure has been fully described by Jamin.1 Most of our oil fields in the Mid-Continent and Eastern districts are subject to this action of capillarity: The fact that the actual reservoir is often far from being ideal in the manner specified above does not preclude the, influence of this phenomenon. The oil, existing under a pressure exerted by the compressed gas, is securely locked in place

Jan 11, 1926

By F. A. Jerabek, H. L. Hartman

This study presents results of investigations in a small model of segregation in discharged fill slurry, the quantity of solids escaping in the drain liquid, and the relationship of solids to slurry concentration and discharge rate. Compressibilities of fine fill material, in dry and wet states and individual size fractions, are compared. Two terms are frequently used in describing the hydraulic placement of fill material underground: hydraulic stowing is mostly associated with the underground flushing of coarse-sized fill material, such as coal washery refuse; while hydraulic backfilling refers to placement of small-sized fill material, e.g., sand or classified mill tailings, mainly in metal mines. Characteristically, in backfilling, only a few hours may elapse between the time the material is hoisted as ore and redeposited as fill underground. Hydraulic filling was first used about 100 years ago to control subsidence in coal mines. It was subsequently adopted in many mining operations all over the world, but its basic concepts have never been adequately studied and analyzed. This is not surprising, when one considers the number of variables involved in the hydraulic backfilling operation. Recently, much work has been done on the problems of transportation of slurries in pipes. Comparatively less research work has been done concerning the physical properties of fill material (compressibility, cementation, permeability, etc.). Very little work has been done on the problems of fill placing, distribution, and segregation of fill material discharged in the mine void. It is the purpose of this paper to explore two of the basic, lesser known aspects of filling: segregation and compressibility in discharged fill slurry. Difficulties in observing the behavior of hydraulic fill slurry during the pouring operation underground, and insufficient knowledge to conduct any kind of meaningful theoretical analysis, suggest experimental model studies. The tests described in the following sections were conducted in the Rock Mechanics Laboratory of the Department of Mining at Penn State.

Jan 1, 1965

By A. L. Holley

Those who are familiar with working gas furnaces will perhaps admit that the ordinary producer is the least satisfactory feature of the- whole system, chiefly by reason of its great waste of fuel, both above and below the fire. The waste of fuel in cleaning the fire has not, as fdr as I am aware, been carefully measured ; it has been roughly estimated at various works as averaging twenty per cent. to twenty-five per cent. The coke that falls into the ash-pit is largely mixed, if not stuck together with clinker; when this coke is not recovered and utilized (and where coal is cheap it does not pay to recover it), the waste is certainly as high as above estimated. Cleaning a fire on a grate (especially a fire of dirty coal, like much of our Western coal), by inserting a few temporary grate-bars, then withdrawing the regular grate-bars and letting the whole lower part of the fire tumble into the ash-pit, must necessarily be wasteful of fuel, but it has been found to be the most practical system. The fire under a boiler should be thin, to insure perfect combustion; hence it may be moved from one side to the other, so that .the clinker and ashes may be uncovered and removed. But a producer fire should be so thick that carbonic oxide only shall rise from it; a thick fire cannot be thus manipulated. In several of the French works the ordinary producer without grates is employed ; the whole body of the fire rests on the floor of the ash-pit. It did not seem to me that less fuel was wasted here than with grates in cleaning fires. The bottom layer of the fire had to be drawn out with hooks, and there was nothing to prevent much coke from coming away with the clinker and ash. A producer shaped like a cupola furnace has many advantages, but if grates are employed the waste of coke in cleaning is not lessened. But the waste at the bottom of the fire is only a part of the waste in the ordinary producer. Mr. Emmerton, chemist to the Juliet Iron and Steel Company, has lately made a number of gas analyses from the producers of that company, worked with impure Illinois

Jan 1, 1880

By J. S. Billheimer, B. H. Sage, W. N. Lacey

A restricted ternary system made up of n-pentane, tetralin, and a purified bitumen was investigated at 70, 160, and 220 °F. Most of the experimental observations were at atmospheric pressure or at 200 psi." However, some experimental measurements were carried out at a pressure of approximately 8000 psi. It was found that the purified bitumen was precipitated from its solution or dispersion in tetralin by the addition of n-pentane and that the separation occurred at lower weight fractions of n-pentane at the lower temperatures. The bitumen-tetralin solutions show some colloidal characteristics at temperatures below 160 °F when near compositions at which the bitumen separates as a solid phase. At states remote from the phase boundaries and at temperatures above 160 °F these characteristics become less evident. Under these latter circumstances the mixtures tend to follow the behavior of true solutions, particularly in regard to the approach to heterogeneous equilibrium. An increase in pressure appears to increase the solubility of bitumen in tet-ralin-n-pentane solutions. This effect is more pronounced at temperatures above 160 °F than at lower temperatures. INTRODUCTION Asphaltic phases of plastic or solid nature have appeared in numerous instances during the recovery of petroleum from underground reservoirs. Such depositions occurring underground appear to have caused adverse production histories for particular wells or zones. Because of this field experience, it is desirable to understand the factors which influence the formation or separation of the asphaltic phases from petroleum. The problem is unusually complex because the number of true components involved is very large and the details of the phase behavior encountered are difficult to ascertain experimentally. The literature relating to asphalts, asphaltines, and bitumen is voluminous and widespread.' Only those references which are directly pertinent to the work at hand are cited. The separation of an asphaltic phase, hereinafter called bitumen? from naturally occurring hydrocarbon mixtures has been the subject of several investigations.2'3'4'5'6 It has been found that as many as four phases4 may be produced from a crude oil by the solution of a natural gas and propane at a pressure of 1500 psi and a temperature of 70 °F. The separation of bitumen from such naturally occurring mixtures results in at least one liquid phase which is substantially free of high molecular weight components.³ The influence of the solution of lighter hydrocarbons on the separation of bitumen from a Santa Fe Springs crude oil has been investigated. The results indicate that in the case of the methane-crude oil system, the quantity of plastic or solid phase separated reaches a maximum between 0.14 and 0.19 weight fraction methane and then decreases until negligible at higher weight fractions of methane. Similiar behavior was encountered in the case of mixtures of ethane and crude oil. The decrease in the quantity of the solid phase with an increase in the weight fraction of the lighter component appears to result from the formation of an additional liquid phase6 in which the bitumen is relatively soluble. The formation of this additional phase probably occurs at a weight fraction of methane close to that at which the quantity of separated solid reaches a maximum. A comparison of the deposition of bitumen in the field with the separation of asphalts from lubrication oil has been made' and apparently the phenomena are similar. The phase behavior of bitumen also appears to be comparable to that of coal tar."' The chemical and physical characteristics of asphalts and bitumen have been the subject of extended investigations which have been reviewed in some detail by Katz.¹º The conclusion was reached that the dispersion of bitumen in a number of organic liquids was not entirely colloidal since it was impossible to isolate individual dispersed particles even with the electron microscope. However, the evidence appeared to indicate that at states close to phase boundaries the extent of the dispersion of the phases influenced the equilibrium to a greater extent than is encountered in many simpler systems. From earlier study of field samples it became apparent that the phase behavior of bitumen-hydrocarbon systems was unusually complex. It was difficult to characterize in detail the phase behavior involved in naturally occurring hydrocarbon systems, even after a relatively extended investigation. For this reason, the study of a somewhat simpler system which still behaved in a similar manner became desirable. Three major constituents were necessary as-follows: a bituminous solid, a liquid constituent which was a reasonably good solvent, and a constituent in which bitumen was largely insoluble. A sam-

Jan 1, 1949

By W. N. Lacey, B. H. Sage, J. S. Billheimer

A restricted ternary system made up of n-pentane, tetralin, and a purified bitumen was investigated at 70, 160, and 220 °F. Most of the experimental observations were at atmospheric pressure or at 200 psi." However, some experimental measurements were carried out at a pressure of approximately 8000 psi. It was found that the purified bitumen was precipitated from its solution or dispersion in tetralin by the addition of n-pentane and that the separation occurred at lower weight fractions of n-pentane at the lower temperatures. The bitumen-tetralin solutions show some colloidal characteristics at temperatures below 160 °F when near compositions at which the bitumen separates as a solid phase. At states remote from the phase boundaries and at temperatures above 160 °F these characteristics become less evident. Under these latter circumstances the mixtures tend to follow the behavior of true solutions, particularly in regard to the approach to heterogeneous equilibrium. An increase in pressure appears to increase the solubility of bitumen in tet-ralin-n-pentane solutions. This effect is more pronounced at temperatures above 160 °F than at lower temperatures. INTRODUCTION Asphaltic phases of plastic or solid nature have appeared in numerous instances during the recovery of petroleum from underground reservoirs. Such depositions occurring underground appear to have caused adverse production histories for particular wells or zones. Because of this field experience, it is desirable to understand the factors which influence the formation or separation of the asphaltic phases from petroleum. The problem is unusually complex because the number of true components involved is very large and the details of the phase behavior encountered are difficult to ascertain experimentally. The literature relating to asphalts, asphaltines, and bitumen is voluminous and widespread.' Only those references which are directly pertinent to the work at hand are cited. The separation of an asphaltic phase, hereinafter called bitumen? from naturally occurring hydrocarbon mixtures has been the subject of several investigations.2'3'4'5'6 It has been found that as many as four phases4 may be produced from a crude oil by the solution of a natural gas and propane at a pressure of 1500 psi and a temperature of 70 °F. The separation of bitumen from such naturally occurring mixtures results in at least one liquid phase which is substantially free of high molecular weight components.³ The influence of the solution of lighter hydrocarbons on the separation of bitumen from a Santa Fe Springs crude oil has been investigated. The results indicate that in the case of the methane-crude oil system, the quantity of plastic or solid phase separated reaches a maximum between 0.14 and 0.19 weight fraction methane and then decreases until negligible at higher weight fractions of methane. Similiar behavior was encountered in the case of mixtures of ethane and crude oil. The decrease in the quantity of the solid phase with an increase in the weight fraction of the lighter component appears to result from the formation of an additional liquid phase6 in which the bitumen is relatively soluble. The formation of this additional phase probably occurs at a weight fraction of methane close to that at which the quantity of separated solid reaches a maximum. A comparison of the deposition of bitumen in the field with the separation of asphalts from lubrication oil has been made' and apparently the phenomena are similar. The phase behavior of bitumen also appears to be comparable to that of coal tar."' The chemical and physical characteristics of asphalts and bitumen have been the subject of extended investigations which have been reviewed in some detail by Katz.¹º The conclusion was reached that the dispersion of bitumen in a number of organic liquids was not entirely colloidal since it was impossible to isolate individual dispersed particles even with the electron microscope. However, the evidence appeared to indicate that at states close to phase boundaries the extent of the dispersion of the phases influenced the equilibrium to a greater extent than is encountered in many simpler systems. From earlier study of field samples it became apparent that the phase behavior of bitumen-hydrocarbon systems was unusually complex. It was difficult to characterize in detail the phase behavior involved in naturally occurring hydrocarbon systems, even after a relatively extended investigation. For this reason, the study of a somewhat simpler system which still behaved in a similar manner became desirable. Three major constituents were necessary as-follows: a bituminous solid, a liquid constituent which was a reasonably good solvent, and a constituent in which bitumen was largely insoluble. A sam-

Jan 1, 1949

By Charles W. Allen

The Athens mine is in the city of Negaunee, Mich. It is one of the larger producers of soft hematite ore on the Marquette iron range. The property is held under lease by the Athens Iron Mining Co., and is operated by the Cleveland-Cliffs Iron Co., which is a partner with Pickands, Mather & Co. in the Athens company. The mine was opened in 1913, and shipments of ore commenced in 1918, the total reaching 3,063,711 tons up to Jan. 1, 1932. Diamond-drilling from surface, together with a knowledge of geological conditions in neighboring properties, gave a comprehensive picture of the location, size and shape of the orebody before shaft-sinking started. Striking east and west, the orebody entered the east boundary of the property at a depth of about 1500 ft. below surface. A pitch of 15" to the west carried it down to about 2500 ft. on the west boundary, about double the depth of that of any soft-ore property heretofore worked on the Marquette Range. The width of ore averaged close to 500 ft., and the thickness 300 feet. The depth of the deposit and its size, together with an overburden of quicksand, which in places reached a thickness of 150 ft., presented unusual mining problems. The use of a caving system made surface drainage into the orebody inevitable, because the north boundary of the deposit was a vertical diorite dike 200 ft. wide, and the south boundary a northward-dipping impervious slate. S. R. Elliott, manager of the mining department of the Cleveland-Cliffs Iron Co., who was superintendent of the mine at that time, conceived the idea of starting at the bottom of the orebody and working upward, reversing the usual mining procedure. This innovation divided the Athens orebody into a series of steps, or blocks, the first of which was adjacent to the western boundary, and therefore in the lowest portion of the deposit. Top-slicing was to start under the capping in this first block by raising from the bottom level, and development and mining were to progress upward in successive blocks to the east. A complete description of the Athens system of mining was

Jan 1, 1934

By F. F. Lines

It is not the intention of the writer to enter into a discussion of the relative merits of the duplex process as compared with the straight scrap and pig iron process, working under the same conditions, but rather to present in a general way several modifications of the former process, and then describe the method adopted by the Maryland Steel Co., as best suited to local conditions, and also to meet the metallurgical problem presented in the removal from the iron of an unusual constituent— chromium. The principal factors to be considered in. deciding whether or not duplexing should be employed are: (1) Chemical constituents of pig iron. (2) Variety and quantity of steel to be produced. (3) Relative cost of pig iron and scrap. (4) Regularity of operation. (5) Capital to be invested. (6) An existing Bessemer plant. Having decided to adopt the duplex process, several combinations may be used, viz.: (1) Acid-lined converter with basic open hearth. (2) Acid-lined converter with electric furnace. (3) Basic-lined converter with basic open hearth. (4) Basic-lined converter with electric furnace. (5) Basic open hearth with electric furnace. The combination of an acid-lined converter with a basic open-hearth furnace is the one most commonly employed, and as it is the one best adapted to the conditions encountered at the plant of the Maryland Steel Co., we will briefly outline the advantages and disadvantages of the different methods of working. There are two general methods of blowing, as follows: (1) The charge is desiliconized and partly decarbonized in the converter. On account of the difficulty in regulating the percentage of car-

Jan 1, 1916

By J. M. Hodge, M. A. Orehoski

THE relationship between hardenability based on a 50 per cent martensite criterion, and that based on higher percentages of martensite in a number of low-alloy steels was discussed in a previous paper by the authors.1 It was found that the differences between the hardenability values based on the 50 per cent martensite and full martensite criterions increased as the hardenability increased and that, in the steels of higher hardenability, these differences were fairly large. Furthermore, it was found that these relationships could be expressed with reasonable accuracy as a function of the hardenability. The importance of the full martensite criterion of hardenability in relation to the attainment of the optimum mechanical properties of tempered martensite was emphasized in the earlier paper. The purpose of the present work is to study the effects of some of the individual alloying elements on hardenability, using three different percentages of martensite as criteria, and thereby to evaluate the role of these individual elements in the general hardenability relationships previously reported. EXPERIMENTAL PROCEDURE Induction-furnace heats weighing 17-lb., of the compositions given in Table I, were cast and forged into 1 ¼ in. round bars. All heats were killed with aluminum additions corresponding to 1 lb. per ton. The compositions were chosen to represent several series of steels, in which only one alloying element would vary and in which the nonmartensitic constituents on quenching would be predominantly bainitic. All bars were normalized from 1650°F. and tempered one hour at I 150°F. prior to the hardenability determinations. Hardenability values are based on metallographic examination of standard Jominy bars, quenched from 1600°F. (I hr. and 20 min. heating time). The general procedure was the same as outlined in detail in the previous paper; (I) that is, the distance from the quenched end of the bar to the point of 0.1 per cent transformation was first measured on the microscope and then the percentage of martensite was estimated at every 0.05 in. from the quenched end, and these percentage values plotted against the distance along the bar. In this case, samples 2 in. long were cut from the quenched end of the Jominy bars and 10 fields were examined and averaged at each distance. The conversion of Jominy distance to ideal diameter is based on a revised correlation curve (Fig. I). This curve is based on work carried out at the Research Department of the South Chicago Works, Carnegie-Illinois Steel Corporation, and represents a direct correlation between hardenability values as deter-

Jan 1, 1946

By Arthur F. Taggart, T. C. Fitt, A. W. Thomas

IT was noticed early by operators that high recoveries and flocculation of the sulphide minerals were closely correlated in agitation-froth flotation. Later, this readily visible flocculation was found almost invariably to be due to the binding together of the oiled sulphides by minute air bubbles, and is now known to be characteristic of pulps in which at least one of the mineral species is coated with an insoluble collecting oil. In 1930 it was reported1 that in differential flotation a correlation exists between Brownian movement of particles in the pulp and their nonfloatability, and that Brownian movement and dispersion are likewise correlated, whence it would appear to follow that dispersion of a mineral particle in a flotation pulp denotes a particle condition unfavorable to flotation. In 1934 it was postulated2 that Brownian movement, dispersion and nonfloatability all flow from the condition of the surface of the dispersed particles. It was also postulated at that time that the surfaces of dispersed particles are ionized, the ionized compound being a product of reaction between a component of the particle and a. component of the pulp, of a mass solubility of the general order of a fraction of a milligram to 15 to 20 mg. per liter. It was then further asserted, and has since been confirmed by Bankoff,3 that sulphides so conditioned with soluble collectors as to be floatable flocculate without the intervention of air bubbles as binding media. The present paper comprises an inquiry into the nature of the bound and counter ions in zinc sulphide dispersed by sodium arsenate. A part of its findings was mentioned in the 1934 paper above cited.2 The tests show that: I. When powdered granular zinc sulphide is immersed in aqueous solutions of sodium arsenate, arsenate ion is abstracted from solution and anchored to the solid surface, while sulphate and lower sulphoxy ions are concurrently displaced therefrom in substantially stoichiometric quantities. 2. The ion counterbalancing the anchored arsenate ion is zinc. 3. Dispersion and Brownian movement of zinc sulphide are concurrently maxima at an arsenate-ion concentration lying between 0.01 and 0.001-molar sodium arsenate. 4. Any condition or reaction that tends to remove the zinc arsenate coating from the zinc sulphide particles decreases dispersion and Brownian movement concurrently. EXPERIMENTAL Three samples of zinc sulphide were used. Lot I was C.P. zinc sulphide, washed well beyond absence of chloride, as shown by test with silver ion. Lot 2 was prepared by precipita-

Jan 1, 1943