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By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to be a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumb-bobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white surface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz.: one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in-

Jan 1, 1873

By James J. Norton, Lincoln R. Page

Effective methods for determining grade and reserves of pegmatites in advance of mining have been developed in recent years. When intensive work began on the economic geology of pegmatites during the early years of World War II, it was widely believed that grade and reserves could be estimated only in a most general way. The literature indicated that not all pegmatite deposits are unpredictable, but statements emphasizing unpredictability and irregularity seem to have been more widely accepted. Many standard references reflect the prevailing opinion that minerals are unsystematic in their occurrence in pegmatites. Pegmatites have been de- scribed as "notorious for their irregular structure," and minerals within pegmatites as "irregularly distributed," "irregularly disseminated,'' of "erratic occurrence," "proverbially erratic in distribution," "characterized by extreme irregularity in size and distribution of the essential minerals, and variety and proportion of the accessory minerals, and "spotty."

Apr 1, 1956

By H. M. Conger

Kaiser Steel Corporation's Eagle Mountain mine is located in the Colorado Desert, 60 miles east of Indio, California. Iron concentrates from the mine are shipped by rail 164 miles to the' Company's steel mill at Fontana, and also to Longbeach, California for export. Temperatures are typical of the lower desert ranging from a high of 120 degrees in the summer to a low of 25 degrees in the winter. The average, annual rainfall of about two inches comes mainly as cloudbursts during the summer months. From its inception, the Eagle Mountain mine has had the problem: of breaking its mine rock. Practices followed from 1949 until 1962 were very costly, did not produce uniformly good fragmentation, and were incapable of sustaining, high production. During this period, every conventional type of explosive was tried and found to be unsatisfactory for one reason or another.

Jan 11, 1965

By Percy Hopkins

KIRKLAND LAKE, the second most important gold area in Ontario, is situated in the north¬eastern part of the Province, 392 miles north of Toronto by railway. It is reached by a five-mile macadam road from Swastika, a village on the Temiska-ming & Northern Ontario Railway, 63 miles north of Cobalt. Gold, was first found at Kirkland Lake in 1911 by W. H. Wright. on claim No. 1830, now a part of the Wright-Hargreaves mine. In January, 1912, the metal associated with various tellurides was found by Harry Oakes and George Tough on the Tough-Oakes property 3/4 mile east of the lake. The shipping of hand-sorted, extremely high-grade ore, valued at $350 to $450 in gold per ton, from this property created great interest and resulted in numerous other discoveries. The early developments of the area, however, were much retarded on account of war conditions, labor troubles, and owing to the ore zone being largely under the bed of Kirkland Lake or in drift-covered depressions. It was not until early in 1918, when the Lake Shore Co. found its rich orebody under the bottom of Kirkland Lake, that the various ore deposits were believed to be more or less continuous along one main vein system. From that time most of the work in the area has been done along the "main vein" with gratifying results. Production began late in 1912, and up to the end of March, 1923, the five producing mines have yielded gold, with some silver, valued at $8,379,403. The production in 1922 was $2,162,548; that of 1923 should be over $3,000,000. The same general assemblage of rocks which occurs at. Kirkland Lake extends easterly for many miles to Larder Lake and beyond; hence there is a large area containing formations favorable for gold prospecting. In this general area numerous prospects are being operated, and among the most promising ones, may be mentioned the Argonaut, Crown Reserve and Asso-ciated Goldfields near Larder Lake. A 25-mile branch railway is now being constructed across the mineral area from Swastika to Larder Lake, passing through Kirkland Lake.

Jan 8, 1923

G. B. WATERHOUSE,* Buffalo, N. -Y. (written discussion?).-One of the most essential features of rail manufacture is the production of rails that will give good service and be free from failures. To this end rails are made to careful specifications and their manufacture is controlled by rigid inspection on the part of both the producing mill and the railroad or its representative, such as the Hunt special inspection referred to in the paper. Captain Hunt refers to the crescent-shape base failures and describes them as ruptures in the rail flanges extending from the outside inward toward the web. This is hardly correct and may be misleading. It has been shown, over and over again, that the base breaks originating in seams invariably start at the center of the rail base; and run longitudi-nally in varying lengths from 3 to 12 in. and sometimes longer. Most of them are from 5 to 8 in. long and then curve outward to the edge of the flange. The split at the center of the base may exist for an indefinite time and not be discovered until the break shows on top of the flange or the piece of flange breaks off. The. stresses that cause the break are explained in two ways: (1) by the eccentric bearing of the rail base, that is taking contact at one side or edge and bringing excessive strain at the center of the base which starts fracture in any seam that may he present at that point; (2) the split may be due to cross strain in the base where this member is thrown into. compression, as happens where a pair of trucks are on opposite sides of the cross tie or rail-base hearing, and the head is put in tension. A careful study of "split base breaks" shows that fully 95 per cent. occur on the tie bearing, which is further evidence that the above de-scribed causes for the initial break are probably correct. These split base breaks are almost invariably progressive, but always start at the center of the rail-base running longitudinally.

Jan 12, 1919

By Julian Kennedy

The different types of blowing-engines in use are so numerous that it would not he practicable to consider them all in this paper. I shall therefore only take up briefly a few well known types. The style of blowing-engine most largely used in this country is the vertical engine with air-cylinder above, cross-head between steam and air-cylinders, and two fly-wheels, each having a wrist-pin in its hub, or in one arm. This kind of engine can be built cheaply, takes up little room and is very accessible. Its disadvantages are that the cross-head is liable to break, and that putting the wrist-pins in the wheels tends to set up vibrations in them. It is likely that on the whole this type of engine will continue to be built quite ex tensively. The same general arrangement has also been used to some extent, but not widely, in horizontal engines. The Bethlehem Iron Company has some very fine blowing-engines of this type, except that they are compound, having the one steam-cylinder replaced by two, side by side. These engines are noticeable not only for the very excellent workmanship on them, but also on account of the weight of the pistons being carried by steam-pressnre applied in chambers in the lower side, the steam being supplied to these chambers through the hollow piston-rods. This arrangement, I believe, has always worked well. Another type of engine which has given good satisfaction is the vertical double-engine, having air-cylinders above, steam-cylinders below them, and cranks at bottom, the engines being coupled to cranks on the ends of the shaft, placed at right angles to each other, the shaft carrying the fly-wheel at its center. Engines of this type, except that they are arranged horizontally, are also used to a con siderable extent. These engines avoid the disadvantage of having wrist-pins in the fly-wheels, and also dispense with the long cross head with its attendant disadvantages. They give a very uniform pressure of blast, and are very convenient for starting. The vertical engines of this type, as compared with the horizontal, take up less

Jan 1, 1894

By P. Duwez, H. Martens

Dimensional changes generally occur during the sintering of metal powder compacts. These changes may have several causes and their magnitude depends upon the numerous variables involved in the process, such as the nature of the powder, size and shape of the grains, compacting pressure, rate of heating, maximum temperature, length of time at temperature, and furnace atmosphere. Among all the variables, time, temperature, and compacting pressure are probably the most important ones, and the effect of each one of the other variables can be studied separately once the effect of these is well understood. The most precise method of studying the phenomenon of dimensional changes in a compact consists of heat treating the compacts at various temperatures for different lengths of time. In this method, only very small specimens can be used, in order to achieve rapid rates of heating and cooling. The technique involved in these measurements is very simple, but is time consuming. Another experimental approach to the problem consists of measuring the change in length of a compact as it is being heated at a constant rate. Although the two variables, time and temperature, are combined into a single one (rate of heating), the results obtained by this technique may be of great interest from both practical and theoretical points of view. The purpose of this paper is to describe a systematic investigation of the change in length during sintering of compacts made of one or several metal powders. Experimental Procedure The change in lenght of compacts during sintering was measured with an automatic recording dilatometer. In this instrument the change in length and the temperature are recorded as functions of time on two separate charts and the rates of heating and cooling may be varied from 1 to 20°F per min. The temperature may be kept constant at any value up to 2200°F during any predetermined length of time and the change in length recorded as a function of time. Provision is made for atmosphere control inside the fused silica tube containing the specimen. Three different magnifications are provided, so that 1 in. on the chart corresponds to 0.002, 0.005, or 0.010 in. change in length. The mechanism following the change

Jan 1, 1950

By C. C. McDermond

In reviewing petroleum development in Venezuela during the year 1936, it is well to bear in mind certain factors that affected progress, although not directly connected with the oil industry itself. At the start of the year, when the present Federal Administration took over the reins of government, reaction against the former regime resulted in some popular uprisings. Although these were entirely political in character, they were not without their effect on the oil industry itself. Such popular agitation really ended with a short general strike in Caracas, Maracaibo and other cities during June, these strikes being based on demands for certain changes in government policies. The strikes were duly investigated and their motives taken into consideration by the executive power or by Congress, and during the year many of the civil, political and administrative laws have been revised. In June and December, however, it was necessary to suspend activities in drilling and production work, particularly in the Lake Maracaibo Basin area. In June a strike caused a five-day shutdown in the main producing fields and on Dec. 14 labor difficulties resulted in a shutdown that continued to the end of the year, which necessitated suspension of all drilling and production in the Lake Basin area and curtailment of shipments to deep-water terminals. Actually, the strike lasted for a period of 42 days, until Federal intervention brought the dispute to a close with minor wage increases to workers hut with no loss of initiative or independence on the part of the oil companies. Operations in eastern Venezuela were not affected by the labor disturbances, production and exports having been reduced in December only in the Lake Basin fields. Well Completions On Jan. 1, 1937, a total of 3384 wells had been completed throughout Venezuelan fields, as compared with 3094 on Jan. 1,1936. Of these wells, 2005 were producers. The 290 completions effected during 1936 were by the following operating companies: Lago Petroleum Corporation, 123 completions; Dutch Shell group, 104; Standard Oil Company of Venezuela, 46; Mene Grande Oil Co., 15; British Controlled Oilfields, Ltd., 2.

Jan 1, 1937

By G. Thodos, R. B. Grieves

A method has been developed For predicting the critical temperatures and critical pressures of binary mixtures of carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen with the normal paraffin hydrocarbons. For carbon-dioxide and hydrogen-sulfide systems, relations are presented that take into account the peculiar behavior of mixtures with closely boiling components, such as carbon dioxide-ethane and hydrogen sulfide-propane mixtures which exhibit minimum critical temperature points. For hydrogen, nitrogen and carbon-monoxide systems, the extreme critical behavior caused by wide differences in pure component properties is established In addition, those fixed gas-paraffin systems which resemble paraffin-paraffin systems are also accounted for. For a mixture of known composition, the pure component critical temperatures, critical pressures and normal boiling points are all that are required to determine its critical point. Graphical relations are presented relating Tc and PC , of the mixture to the pure component properties. From the treatment of 12 carbon-dioxide and hydrogen-sulfide systems reported in the literature (74 mixtures), the expected error lor the critical temperature is approximately 1.5 per cent, and for the critical pressure, approximately 2 per cent. From the treatment of six hydrogen, nitrogen and carbon-monoxide systems reported in the literature (30 mixtures), the expected error for both the critical temperature and critical pressure is approximately 2.5 per cent. The relationships, which have been developed with only normal paraffins as the hydrocarbon components, may be extended to those isoparaffins and olefins which fall within the allowable volatility ranges. INTRODUCTION Many of the fixed gases — carbon dioxide, hydrogen sulfide, nitrogen, hydrogen, carbon monoxide and oxygen — occur in natural mixtures with hydrocarbons. Carbon dioxide and hydrogen sulfide are frequent components of the fluids produced from underground petroleum reservoirs. Nitrogen, carbon dioxide and hydrogen sulfide are present in varying quantities in most natural gases and gas-condensate well effluents. Hydrogen mixtures are of considerable interest in many phases of refining processes of petroleum. The determination of the critical temperatures and critical pressures of such mixtures is of value in vapor-liquid equilibrium studies, for the prediction of the characteristics of underground reservoirs, and for reduced-state correlations of PVT, transport and thermodynamic properties. The accurate estimation of the critical point for binary mixtures is an important initial step toward a complete analysis for the establishment of the critical temperatures and pressures of multi-component mixtures. Methods for predicting the critical temperatures and critical pressures of binary hydrocarbon systems have already been presented in the literature.8 It is possible to apply these existing methods to fixed gas-paraffin mixtures, but due to their unusual critical behavior, values calculated deviate considerably from experimental values. For systems containing trace quantities of the fixed gases, these methods are acceptable; however, for systems containing more than 5 mol per cent of the fixed gases, these utterly fail to produce reasonable critical values. Consequently, in this study a method has been developed for handling such binary mixtures over the entire composition range. CARBON-DIOXIDE AND HYDROGEN-SULFIDE SYSTEMS The critical behavior and the vapor pressure behavior of mixtures of carbon dioxide and hydrogen sulfide with paraffinic hydrocarbons may be quite similar or quite dissimilar to that of paraffin-paraffin mixtures, depending on the volatilities of the components involved. The critical temperature and normal boiling point of carbon dioxide are very close to the corresponding values for ethane, while its critical pressure is considerably higher than that of ethane. The normal boiling point of

By J. O. Scott

Transient pressure behavior of wells intersected by a single vertical fracture has been examined by means of a heat pow analogy. Results are correlated in terms of dimensionless pressure change and dimensionless transient time. The resulting curves are found to lie between the dimensionless curves for a cylindrical well and a line source when effective well radius is expressed as one-fourth of the total fracture length. Results are also shown for various degrees of afterflow. Use of the curves provides a means of determining reservoir permeability, wellbore radius, and thereby fracture length, even when the final slope of the transient curve is not obtained. Superposition of curves may be used to confirm existence of vertical fractures in the reservoir adjacent to the well or to indicate a damaged zone on the fracture face. INTRODUCTION Hydraulic fracturing has become a standard well completion practice for the purpose of increasing flow. Results are normally gauged in terms of some sort of "stabilized" flow rate established before and after the treatment. This procedure may be misleading because pressures in or around the well do not become "stabilized" during the test period. Transient pressure tests on fractured wells can overcome the objections to stabilized flow tests by indicating when a stable pressure gradient is reached. In addition, the transient pressure tests can be used to determine formation flow capacity and effective wellbore radius. The effective wellbore radius may be used as a measure of the success of the fracturing operation. The slope and position of the transient pressure-log time curve may be used to determine the flow capacity and wellbore size after sufficient lapse of time so that the pressure gradient in the vicinity of the fractures becomes constant. However, in tight reservoirs or in short tests this condition may not be reached. Presence of the fractures in tight reservoirs may cause a constantly increasing slope to the transient pressure curve. If this slope is picked too soon, formation flow capacity will appear high and the fracture size will appear too small. This paper is intended to clarify the early transient behavior of vertically fractured wells. It shows how formation flow capacity and wellbore size can be determined even though the maximum slope of the transient pressure curve is not obtained during the test. Development of the techniques of transient pressure analysis for wells has been summarized by Perrine.' He reviews the various definitions of wellbore effects such as skin effect, productivity ratio, damage factor and condition ratio. In the present paper, use of these terms is avoided by defining an effective wellbore size. For the fractured well this effective wellbore size is larger than the actual wellbore. Assumptions made are constant flow rate at the well, constant fluid compressibility, constant fluid mobility and uniform porosity and formation thickness. From the basic differential equations of flow, two different solutions may be obtained. The first, the line source solution, is commonly used in transient pressure analysis.' It expresses the change in pressure at any radius due to withdrawal or injection of fluid at the line source from an infinite reservoir at uniform initial pressure. This equation, in oil field units: is

By R. M. Genevray, M. B. Bever, E. J. Suoninen

THE martensitic transformation in the ß-phase of the Cu-Zn system has been the subject of several investigations. The transformation is known to be reversible and to be affected by stress. Its temperature range has been determined as a function of composition. In the investigation reported here, the effect of tensile stresses on the transformation was investigated quantitatively. Some information was also obtained on the thermoelastic behavior of the martensite formed in the first stages of the transformation. Most of the experiments were done with alloy E of an earlier investigation;' this alloy analyzed 60.49 pct Cu and 39.51 pet Zn by weight. The methods of shaping and heat treatment were also essentially the same as those previously used. The stress was applied to the specimen immersed in a cooling liquid. The transformation was followed by measuring the electrical resistance with a Kelvin bridge and the elongation with a cathetometer. Fig. 1 shows the M, temperature as a function of stress. Resistance and strain measurements gave essentially identical values. The results suggest a roughly linear relation between M. and in the range investigated, up to 12 kg s mm". At higher stresses, plastic deformation begins to interfere seriously with this relationship. The increase of M, with stress is consistent with published work on the effect of stress on the martensitic transformation. The slope of the curve, 4°C per kg mm ", is of the same order of magnitude as the corresponding value calculated for steel.' Fig. 1 also shows the difference, AM, between the temperature of 50 pct transformation on cooling, as measured by changes in length, and that of 50 pct reverse transformation on heating. This difference, which may be considered a measure of the hysteresis, increases with stress; the decrease at highest stresses is probably associated with plastic deformation. Preliminary work using only resistance measurements was done with an alloy containing 60.15 pct Cu and 39.79 pct Zn by weight. The results indicated higher values o-F M, in agreement with the known variation of M. with composition.' The effect of stress on M, (2°C per kg mm-') was of the same order of magnitude as that shown in Fig. 1 for composition E. An increase in hysteresis with stress was also found. The following experiment was made in order to investigate a partially transformed structure. A specimen of alloy E was cooled to — 85°C under a stress of 4.7 kg mm-'. Under these conditions, the martensitic transformation started but did not go to completion. The stress was then released and the specimen cooled to — 105°C. Fig. 2 shows the measured elongation c. The first change in the slope of the curve indicates the beginning of the transformation under stress. Removing the load at —85°C caused a decrease in length to the value corresponding to the elastic elongation of the parent phase resulting from the applied stress. Hence, the marten-site formed in the first part of the experiment apparently disappears completely and without hysteresis upon the release of the stress. The increase in length on further cooling indicates renewed formation of martensite. These conclusions are consistent with the concept of "thermoelastic" martensite," which has been confirmed by test." Acknowledgments The authors are greatly indebted to Professor M. Cohen for his advice and encouragement. They also thank F. Paxton for assistance. Thanks are due the American Brass Co. which supplied the alloys. References E. Kaminsky and G. V. Kurdjumov: Zhur. Tekhn. Fiziki SSSR (1936) 6, p. 984. A. B. Greninger and V. G. Mooradian: Trans. AIME (1938) 128, p. 337. "J. E. Reynolds, Jr. and M. B. Bever: Trans. AIME (1952) 194, p. 1065; Journal of Metals (October 1952). 'A. L. Titchener and M. B. Bever: Trai~s. AIME (1954) 200, p. 303; Journal of Metals (February 1954). " 3. A. Kulin, M. Cohen, and B. L. Averbach: Trans. AIME (1952) 194. p. 661; Journal of Metals (June 1952). "J. K. Pate1 and M. Cohen: Acta Metallurgica (1953) 1, p. 531. 'C. Crussard: Comptes Rendus (1953) 237, p. 1709. ' G. V. Kurdjumov: Zhur. Tekhn. Fiziki SSSR (1948) 18, p. 999. G. V. Kurdjumov and L. G. Khandros: Dokl Akad. Nouk. SSSR (1949) 66. p. 211.

Jan 1, 1957

By F. H. Vitovec, D. W. Hoeppner

Pusk-pull fatigue tests were conducted on copper tricrystals of 99.988 pct purity to ascertain the role of grain boundaries in the initiation and propagation of fatigue cracks. Significant differences in behavior were found for specimens which possessed different transverse-boundary misorientation. In speciwens with low boundary angles cracks initiated within the transverse boundary, while higher angles led to transcrystalline fatigue failure. It is suggested that at low angular misorientation moving dislocations may interact with dislocations of the boundary or dislocations present in adjacent pains on favorably oriented glide planes, thus initiating a fatigue crack. MANY fatigue studies have been concerned with fatigue-crack initiation within grains and the mechanism causing initiation and propagation1-3 Although the initiation of fatigue cracks in or near grain boundaries of pure metals has been observed and reported in the literature, the mechanism of this phenomenon has received little attention.4"11 EXPERIMENTAL PROGRAM Testing Procedure. To investigate the role of grain boundaries regarding initiation and propagation of fatigue cracks, copper tricrystals were tested in push-pull. Axial-stress tests were used to avoid the stress gradients introduced by stressing of some other nature. Copper was selected as the most suitable test material since extensive work has been done on the formation of fatigue-induced slip in copper. Tricrystal specimens were used to provide a grain boundary geometry with one boundary transverse to the principal stress axis and one or more boundaries nearly coincident with the direction of maximum resolved shear stress. The boundary energy and the slip characteristics in the vicinity of the transverse boundary depend on the relative orientations of grains across the boundary. Testing was done at room temperature, at a frequency of 700 cpm, in an atmosphere of either air or argon. It is known that the incidence of grain boundary cracking increases with increasing temperature and decreasing frequency.4 The fatigue machine applied a uniaxial tension-compression load to the specimen by a flat spring which was actuated by an adjustable eccentric. Use was made of an adjustable head and a load cell which had strain gages mounted at 120-deg intervals around its periphery, thus providing a means for eliminating any detectable superimposed bending moment. A clip gage was mounted between the gripping heads to record the cyclic strain amplitude applied to the specimen. Each specimen's hysteresis characteristics were recorded by supplying the load and strain signals to an oscilloscope. Microstructural changes were observed and recorded with an optical microscope which was mounted on the fatigue machine. Immediately prior to insertion in the machine, each specimen was chemically polished. Extreme care was exercised while inserting the specimen in the test machine to avoid either bending the specimen or introducing a mean load. Each specimen was stressed in the tensile direction first and subsequently the load was reversed. Specimen Preparation. Tricrystal fatigue specimens of 99.988 pct Cu were grown from the melt using a modified Bridgman technique. Ingots about 1 in. high were grown to the configuration shown in Fig. 1. Upon sectioning the resultant ingot, several specimens were provided with an identical shape and grain boundary orientation. Except for plane sectioning and final polishing, this method eliminated machining the specimens. The apparatus used for growing the tricrystals is shown in Fig. 2. A spectrographically pure graphite mold, Fig. 3, was inserted in a vycor tube which was mounted on a vertical zone-refining table. Prior to insertion in the tube the mold was assembled as follows. The insert and graphite rods were fixed in position in the mold. The copper was then placed in the mold and the entire mold assembly was positioned in the vycor tube, Fig. 2. At this point the tube was sealed, evacuated, purged with helium gas, and finally placed under a slightly positive helium pressure. The heating coil was then adjusted to melt the copper charge, after which it was raised at a speed of 4 in. per hr. It is also possible to use

Jan 1, 1964

By T. H. Alden

A correlation has been found in rock-salt structure single crystals between the latent hardening, measured by the direct stress activation of oblique slip systems, and the stress-strain behavior in simple compression. Materials with high latent hardening, like LiF, strain-harden at a low rate (Stage I) even when severely constrained. KCl, in contrast, shows low latent hardening and a tendency to strain-harden at a high rate (Stage 11). This correlation suggests that oblique slip is essential for Stage II hardening of these materials. THE role of secondary slip in the strain hardening of metal single crystals is a topic of lively controversy. On the one hand are theories in which secondary dislocations participate directly in Stage II hardening in the fcc metals, for example through the production of sessile dislocations,1 forest intersections, or jog formation. Much of the experimental evidence on which these theories are based has been reviewed by Clarebrough and Hargreaves.~ On the other hand, a recent theory5 denies that secondary slip has an essential role in Stage II hardening or in the transition from Stage I to Stage 11. In the latter view, Stage I is not terminated by an increase in the activity of secondary systems but by the exhaustion of undeformed material.6 The experiments reported in this paper will not resolve this controversy since the materials being studied are cubic ionic crystals rather than metals. However, the results do show in an unusual way a direct connection between "secondary" (nonortho-gonal or oblique) slip and strain hardening in these materials. Specifically, a correlation has been found between two independently measured properties, first the latent hardening of oblique (110)(1i0) slip systems as measured by direct stress activation of these systems, and second the stress-strain behavior at small strains. From prior work, it was known that in most cubi-cally oriented rock-salt structure crystals, two orthogonal slip systems operate and exclude the other equally stressed pair, oblique to the first pair.7'8 This observation apparently indicates that a significant interference exists between slip on oblique (110) planes and a relatively small interference between orthogonal (110) planes. The present experiments were begun with the intent of obtaining a quantitative measure of this difference by means of a study of latent hardening in these crystals. I) EXPERIMENTAL METHODS The experiments were basically of two types, first the determination of stress-strain curves by compression along a single (100) axis, and second the measurement of latent hardening by compressive prestrain along one cube axis followed by the determination of the yield stress in a second (latent) cube direction. All tests were done at room temperature in an Instron machine by compression between lapped, parallel steel faces. Three specimen shapes were used. For long crystals (nominal dimensions, 1/8 in. square by 1/2 in. long) the ends were lubricated with an oil-graphite mixture. Superior results with short crystals (about 1/8 in. cube) were obtained using 0.003-in. teflon film.' Thin crystals (1/4 in. square by 3/32 in.) were used for latent-hardening measurements and similar results were obtained with either lubricant. Test specimens were cleaved from Harshaw single crystals which had been irradiated to a dose of lo8 roentgen using a cobalt-60 source. The irradiation raises the yield stress and tends to prevent plastic deformation during sample preparation.10 Prior to testing, the irradiation hardening was removed by an anneal at 400°C. Ideal compression specimens have flat, parallel faces. In short specimens particularly, satisfactory results demand a close approximation to this ideal. In the present work, cleaved surfaces were often used directly as compression faces. The degree of success using this method depends on two factors: 1) the smoothness of cleavage faces, and 2) the extent to which the crystal is deformed or crushed by the chisel during the cutting of a long crystal into short pieces. Unfortunately, only one material of those studied, LiF, was completely satisfactory. NaF, NaC1, KC1, and KBr behaved less well so that

Jan 1, 1964

By J. B. Wagstaff

The raceway in front of the tuyere of the blast furnace has been studied quantitatively and a correlation obtained for the penetrastudiedtion of the blast. Some evidence is presented for the height and width of the raceway which suggests that all the raceways of a ffurnace overlap. The size of the coke in this zone has been measfurnaceoverlap.ured photographically during normal operation and results are given for the various areas. IN an earlier paper,' it was shown that a raceway exists opposite each tuyere of a blast furnace. This raceway is formed by the jet effect of the air emerging from the tuyere and consists essentially of a turbulence in which coke particles are recir-culated at high speed. Its presence was deduced originally from observations on movies taken with a high-speed camera through the tuyeres of various furnaces and was confirmed by experiments made on a model. In the model described,' this raceway was shown as operating in a vertical plane only, although there was a suggestion in the motion-picture film exhibited at that time that the raceway was three dimensional, unless artificially restricted. There was also some doubt then about the factors influencing its size. This paper describes the next steps in the investigation. Since the size of the raceway is obviously of importance in the operation of the furnace, it seemed worth while to study the subject more carefully. It is probably in this region that about half the coke in the furnace is consumed, so that the movement of the stock column may well be controlled by raceway behavior. Furthermore, there is some evidence to suggest that the coke is packed densely in the center of the furnace to form the "dead man" and more loosely above the raceway. It is therefore probable that the bulk of the gases passing up the stack flow from the top surface of this raceway. Clearly then, a knowledge of this critical zone is of interest to the blast furnace operator, and the first half of this report is devoted to a quantitative discussion of the subject. A further topic of interest among operators is the degree of breakdown of coke in the furnace, with which is inseparably linked the importance of a strong coke. Indeed, the whole question of the optimum size and type of coke may be as dependent on the condition of the coke in the bottom of the blast furnace as at the top. Attempts have been made from time to time to obtain samples of coke from the tuyeres and other furnace openings but they all suffer from the fact that the coke is filled to a varying degree with metal and slag and is probably broken up by the very act of taking the sample. It has proved difficult to make any reliable studies of coke size by these methods. However, it did seem possible to use the highspeed movies mentioned earlier1 to estimate the size of the coke. These movies provide an accurate record of individual coke particles so that, in theory at least, it should be possible to measure the size of the particles one by one and to obtain, for the first time, information on the coke being blown around the raceway under actual operating conditions while the furnace is performing normally. Such a study has been made and is discussed in the second half of this paper. The results obtained enabled the blast furnace data to be correlated with the model results given in the first half. Raceway Size In order to make a quantitative study of the size of the raceway it was necessary to devise some apparatus of laboratory scale, which could be handled quickly and easily. This focused attention on models, which in turn means that the laws of similarity governing this particular process must be ascertained. Method of Procedure: Since the work was to be carried out on a smaller scale than the blast furnace, the linear dimensions of the model became unimportant provided that the scale was known; it is only important to insure that the container does not affect the raceway being observed. The studies therefore were carried out in a glass-sided box, 11 in. high x 7 in. wide x 3 in. deep, using air jets ranging

Jan 1, 1954

By Henry H. Logan

THE purpose of mine-hoist safety controllers is to prevent hoists from being operated at speeds above those considered safe and expedient, to ensure proper acceleration and retardation near the ends of travel, and to prevent overwinding. In other words, they are to safeguard the normal speeds and movements of the hoisting drums and cages. The object of this paper is to explain the fundamental principles of hoist controllers, and to aid in their selection, installation, and maintenance. There have been many designs of mechanical hoist controllers, the basic elements of which as ultimately developed consisted of a flyball governor and another movable member supported by a frame and arranged to move in a vertical, horizontal, or rotary direction, depending upon the particular design, the whole mechanism arranged to be driven in synchronism with the hoist drum. In case of overspeeding, inadequate retardation, or overwinding, a pawl or catch controlled by the governor would engage teeth or dogs on the moving member, which through mechanical connections would cut off the power and set the brakes. Since in strictly mechanical hoist controllers valuable time was lost while the various mechanical movements took place, an important development was the invention of controllers partly mechanical and partly electrical. This type of controller has a governor and movable cams to be driven in synchronism with the hoist drum, the governor representing the hoist speeds and the cams profiled to form a pattern for retardation, representing the travel of the cages in the shaft. This type is also provided with an overspeed switch and usually with a pair of selective-limit switches, one for the top limit and the other for the bottom. In overspeeding or failure to retard in accordance with the profile of the cam, the overspeed switch will be opened, or if the top or bottom limit is overrun one of the limit switches will be opened, breaking the retaining circuit of a contactor or magnetic latch, causing the power to be cut off and the brakes applied. When the speed falls to the predetermined safe speed, the overspeed switch closes, and a hoist equipped with power-operated brakes controlled in emergency by a solenoid-operated valve can be restarted immediately by simply moving the master control lever to the "off" position and then applying power-unless brake interlocks are used, in which case the brake lever or levers must also be brought to the "applied" position, after which the hoist can be restarted in the usual way. When hand-reset weights instead of solenoid-operated mechanism are arranged to set the brakes for emergency, it is necessary to reset the weights manually, besides bringing the master control lever to the "off" position before the hoist can be restarted. Should a final limit be slightly overrun, and a stop made with a limit switch held open by a cam, it is necessary for the hoistman to use a "backing-out" switch which short-circuits the overrun limit switch, reestablishing the hoist-control circuit, and simultaneously opening the

Jan 1, 1940

By D. W. Fuerstenau

MEASUREMENT of zeta potentials is a useful tool to study the surface chemistry of minerals under flotation conditions.1,2 Because there is continued interest in this approach, the apparatus for obtaining zeta potentials of nonconducting solids by the streaming potential method is outlined here. Fig. 1 illustrates the streaming potential apparatus." The streaming potential cell or plug consists of two 24/40 standard ground joints (4) joined with a piece of pyrex tubing 60 mm long and 12 mm in diam (5). The electrodes are made of bright platinum disks 19 mm in diam and 1 mm thick through which 0.5-mm holes have been drilled (6). To the surface of each is welded a piece of 80-mesh platinum gauze. Each electrode is permanently mounted on the ends of the inner parts of the two standard joints by means of a platinum wire (7) which connects it to the tungsten seal at the end of the cell (8). For ease in cleaning and handling the apparatus, the streaming cell is fastened to the 500-ml reservoir flasks (1) by means of two 18/9 ball and socket joints (2). This particular arrangement permits passage of the solution in either direction through the plug of particles. Flow of solution can be stopped by a stopcock (3). One of the reservoir flasks has a large opening to permit insertion of either a thermometer or a pair of electrodes for measuring pH of solutions within the system. In making the experiments, the plug is filled with 48 to 65-mesh particles, but a layer of 28 to 35-mesh particles is placed at each electrode to prevent any of the finer particles from passing through holes in the electrodes. The assembled apparatus is shown schematically in Fig. 2. To eliminate CO2 from the solutions, all experiments are conducted in a nitrogen atmosphere. Nitrogen, used to drive solutions through the plug, is passed through a bottle of concentrated KOH solution to remove CO2 (9). A 9-liter ballast reservoir (10) is used to maintain a more nearly uniform pressure. A series of stopcocks controls the direction of flow nitrogen to the flasks (11). Tubes of as-carite prevent backflow of CO2 into the system (12). Driving pressure, which can be set at any desired value, is measured with either a water manometer (13) or a mercury manometer (14). Reservoir flasks have side arms for making pressure corrections for the difference in water levels in the flasks. Streaming potentials are measured by the circuit illustrated in Fig. 2. The electrodes from the plug are connected through mercury wells (15) to a reversing switch (16), which reverses the polarity of the electrodes depending on the direction of flow of solution through the plug. The streaming potential is measured with a Leeds and Northrup type K2 potentiometer (17). Proper choice of null instrument is important because Eq. 1 assumes that the current which escapes through the measuring instruments is negligible. An ordinary galvanometer cannot be used to determine the null point because

Jan 1, 1957

By H. Stuart, L. Zwell, N. Ridley

specimen that was subjected to 700°C for 250 hr is shown in Fig. 2(c). The precipitates in this foil appear round and exhibit only very faint strain contrast. From this evidence, along with that described above for the symmetry of the strain field, it may be concluded that this coherent precipitate is spherical, which is generally the favored shape for coherent precipitates when the lattice parameter mismatch is small.12 These observations are consistent with the assumption that this precipitate is the y' (Ni3Al, Ti) phase. y' is known to be spherical in the early stages of precipitation. It is fcc and is similar in composition to the matrix and thus would have contrast similar to that of the matrix as do these precipitates. Direct identification of the spherical precipitate did not prove possible because of its low volume fraction and small size. The results of this investigation suggest that the increases in yield strength and the decreases in elongation observed in 45-Fe 30-Ni 20-Cr alloys containing about 0.4 pct A1 and 0.4 pct Ti on prolonged aging at 550" to 700°C are very likely due to the presence of a coherent, spherical precipitate, thought to be y'. Mi-crohardness measurements indicated that the precipitation of semicoherent M23C6 resulted in some matrix hardening. However, this precipitation process occurs much more rapidly than the changes in mechanical properties at these temperatures. 1C. L. Clark, J. J. B. Rutherford, A. B. Wilder, and M. A. Cordovi: J. Eng. Power, 1962, vol. 84, p. 258. 2 F. A. Comprelli and U. E. Wolff: USAEC Report GEAP-4745, General Electric Company November, 1964. 3C. N. Spalaris: A Monograph, USAEC Report GEAP-4633, General Electric Company, July, 1964. THERE have been many X-ray investigations of the room temperature lattice parameters of austenite which has been retained in quenched steels of various carbon contents. The results of these investigations have been collected by Wrazej,1 Wever et al.,2 and by Roberts3 and are included in Fig. 1 due to Pearson.4 The dashed line in Fig. 1 was considered by Roberts3 to most reliably describe the variation with carbon content of the lattice parameter of retained austenite. This line is given by the equation: a (Å) = 3.555 + 0.044 wt % C and recent unpublished measurements by one of the authors (LZ) support this relationship. The object of this communication is to draw attention to a relationship which describes the variation of the room temperature lattice parameter of 'equilibrium' austenite with carbon content, and which is different from that for retained austenite. The relationship a(Å) = 3.573 + 0.033 wt % C has been obtained from lattice parameter measurements made on equilibrium Fe-C austenites at elevated temperatures, which have been extrapolated to room temperature. The room temperature lattice parameter of 3.555Å which the Roberts' relationship gives for pure y-Fe is no: in agreement with the value of 3.573Å obtained when the high temperature lattice parameter data of Basinski et aL.5 and of Goldschmidt6 is extrapolated to room temperature. A linear extrapolation was

Jan 1, 1970

By F. Weinberg

The distribution of solute during the progressive solidification of dilute Sn-Ag alloys was determined in both solid and liquid as a jbnction of growth rate, rod diameter, temperature gradient, and solute concentration, using radioactive tracer techniques. The results indicated that partial mixing occurs in the liquid during freezing for most of the conditions investigated, approaching complete mixing for larger rod diameters (>2mm) and slow growth rates. Measured solute distributions were fitted to distribution functions based on diffusion controlled solute transport in the liquid state, by treating the normal solute diffusion constant and distribution coefficient as variable solute transport and segregation parameters. Values of these parameters were determined for the growth conditions investigated. Observations were made to determine whether mixing in the liquid was primarily due to volume changes in freezing or to differences in density between solute and solvent. The former effect was investigated using a selected Sn-Bi alloy as a solvent with zero volume change on fusion, and the density effect was studied using vertical solidifications of Sn-In and Sn-Ag alloys, systems having, respectively, very small and large differences in density between solute and solvent. The result indicate that mixing in the liquid cannot be primarily attributed to either volume changes or density differences. THE solute distribution in progressively solidified rods of dilute alloys, in which there is complete mixing in the liquid, is given by the expression1 where C, is the solute concentration in the solid at the point where the fraction g of the material has solidified, C, is the initial solute concentration and k is the equilibrium distribution coefficient. If it is assumed that there is no significant con-vective mixing in the liquid, then the solute distribution in the initial portion of a semi-infinite rod has been calculated to be2 where t is the time from the start of freezing and x1 is the distance in the liquid ahead of the solid-liquid interface at time t. Expressions [1] and [2] describe the limiting cases of solute distribution in the liquid, i.e., complete mixing, or no convective mixing; in practice it might be expected that the solute distribution would be somewhere between these two cases. pfann3 has suggested that Eq. [I] is applicable for partial mixing, as well as complete mixing, if an effective distribution coefficient k1 is used instead satisfactorily describes solute distributions in rods of magnesium, n-g, and b-sb6 alloys that were progressively solidified from the melt without mechanical mixing. The values of kl were observed to depend on the growth rate4-6 and the temperature gradient.6 The purpose of the present investigation was to measure solute distributions in both the solidified rods and the melt as a function of the solidification variables, and to determine to what extent the observed solute distributions could be described by the above theoretical expressions, keeping in mind that expressions [2] and [3] have been derived solely for the case of diffusion controlled solute transport in the liquid and are not theoretically applicable to

Jan 1, 1963

By O. D. Gonzalez

ThIS communication presents the results of a determination of the permeabilities of hydrogen and deuterium in a iron from 360° to 560°C. Recently Heu-mann and primas' have given values of the diffusivity and solubility in a iron of the two isotopes from which the permeability can be calculated. The work reported in the present communication, however, is a direct measurement of the rate of permeation of the isotopes through an identical iron specimen under the same conditions, so that systematic errors can be minimized in the calculation of the ratio of the permeabilities—the value which is usually of main importance in establishing limits for isotopic differences in diffusive processes. Experimentally the procedure used was the usual one: a steady-state flow of gas produced by a pressure difference across an iron membrane was observed as the pressure rise with time in a previously evacuated, calibrated volume connected to the outlet side of the membrane, while a constant pressure of gas was maintained on the opposite inlet side. The membrane was a cylindrical tube 9.38 cm long, 0.730 cm inside diam, 0.187 cm wall thickness, fabricated of 99.95 pct vacuum-melted National Research Corp. iron (less than 0.003 pct C). One end was sealed by a heliarc-welded iron (99.95 pctj lid of 0.147 cm thickness; the other end of the tube was welded to a 304 stainless-steel tube (0.318 cm ID and 0.318 cm wall) which connects to a vacuum system and to the calibrated volume including a dibutylphthalate manometer. The temperature of the iron membrane was maintained constant to ±0.l°C and was measured with an iron-constantan thermocouple which was calibrated against a standard Pt/Pt-Rh thermocouple: the temperature variation along the length of the membrane did not exceed ±0.5°C. Hydrogen was allowed to pass through the membrane assembly for 72 hr at 615°C before permeability measurements were begun. The system was tested at temperature before and after the experiments by a substitution of helium for hydrogen in the inlet side; under these conditions the pressure rise observed in the outlet side was negligible at all times. The gases used for the permeability measurements were 99.95 pct Matheson prepurified H2 and 99.7 pct D2 (0.3 pct HD) from the Isomet Corp. The gases were dried with liquid N2 before use. In Fig. 1 the logarithms of observed flows, jt, for a pressure difference of 73.4 cm Hg are plotted against T-1 Each point in Fig. 1 represents the slope determined by a least-square evaluation of a plot of the pressure in the outlet side of the membrane against time, including at least two separate sets of observations. Each point in the figure has an uncertainty of ±0.6 pct arising from the experimental uncertainty in the pressure and time measurements. The standard deviation of the observed pressures from the straight lines in all cases is less than the experimental precision of the measurements. The observed flow, jt, includes a small but not negligible flow through the stainless-steel connection.

Jan 1, 1968

By Samuel G. Vera

INTRODUCTION The Climax Mine is a property of Climax Molybdenum Company, a division of AMAX Inc. Climax is located in the central part of the Colorado Mineral Belt on the west slope of the Tenmile Range, Lake County, Colorado at 3,425' m. above sea level. Climax Mine, the largest single producer of molybdenum in the free world, has been a cornerstone of mining in the State of Colorado for many years. Before molybdenum was known, the early hunters of gold and silver laid their hands on the outcrops of the Climax deposit and left it as low quality lead or graphite without much value. Today, 44,000 TPD of ore is extracted from the heart of Bartlett Mountain. The molybdenum, separated from the ore, is vital for mankind, being used for everything from fertilizer to fine components of aerospace ships, because of its valuable physical and chemical properties. The operations at Climax have never remained static. Constant demand for the "gray gold", and technological advancements, have converted Climax into an "open book of technology", where learning the still-hidden secrets of mining is a continuing process. (All figures related to tons are metric tons) BRIEF HISTORY The mine produced its first molybdenum ore in 1918. It was shut down in 1919, resumed production in 1924, and has been in continuous production since that time. During World War 11, a peak of 20,000 tons per day was reached, then tonnage dropped from 1945 to 1950. Since 1951, production has been in- creasing, reaching a peak of 46,000 tons per day during the month of June, 1980. Early mining used shrinkage stoping. Block caving using the grizzly system was introduced in the early 1930's. Caving methods were improved through empirical studies of rock behavior and by trial and error, evolving a very efficient mining method by the late 1940's. This form of continuous retreat panel caving, with small modifications, is still used today, and has made the Climax Mine one of the biggest underground mines in the world. The Climax Mine, synonymous with molybdenum, was essentially an underground mine until 1973 when the open pit was introduced. Since then, both mining methods have operated successfully. Current production is 60% from underground, and the remaining from the open pit. Climax has been in continuous operation for 56 years, and as of December 31, 1980, more than 386 million tons of ore have been mined. The orebody is not fully defined, and at the present mining rate, the known life span of the mine will be to the year 2020. GEOLOGY The Climax deposit is a large low-grade porphyry molybdenum deposit somewhat similar to porphyry copper deposits, with a well- mineralized quartz molybdenum stock work sys- tem. It lies within the pre-Cambrian granites and schists and the Tertiary Climax porphyry. The age of mineralization is thought to be mid-Tertiary and is characterized by fracture filling and replacement through silicification. The main economic mineral is molybdenum, with pyrite, cassiterite and wolframite as by-products. Fluorite and topaz also occur, but are not recovered at this

Jan 1, 1981