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By H. Furman Byars

INTRODUCTION of bottom dump hauling units into the Ray, Ariz., stripping operation of the Isbell Construction Co., was motivated by several reasons, with what appears to be debatable results. The accepted theory of truck design for use in open-pit holds that end dump vehicles are the most adaptable for the work. But, because operations of the bottom dump, under certain construction and haulage conditions, proved economically feasible, the unit was put to work in the Ray copper pit. The decision to try bottom dump was reached after considerable observation of the unit in action on construction of earth filled dams, levees, airport construction and several other similar tasks. Basic tire design also motivated the choice. All things being equal, a vehicle running on low pressure single tires will outperform another operating on dual high pressure tires, providing load carrying capacities are the same. The investment required to equip a vehicle with four single tires to handle the same load as one with dual tires mounted on two axles and single front axles is about 60 pct greater. Thus, in order to reach the break even point on tire costs, single tires must operate 60 pct longer. Comparison is made with a truck outfitted with 10 16:00x25 tires. Two other factors were considered in selecting bottom dump trucks. It was felt the bottom dump principle would work well in dumping ore into a hopper where gate design fits this particular method. Also, with the absence of hydraulic dumping, ore pollution with oil is reduced. The mechanical simplicity of the unit also lent weight to its choice. Ordinary reasoning indicated maintenance costs would be low compared with other units carrying similar loads. The bottom dumping principle is not new. It dates back to the days when horses were used to haul the same kind of rig. The unit employed at Ray holds 25 cu yd struck measure, or approximately 42 short tons. Dumping is accomplished by releasing an air cylinder opening a dog holding the doors. Doors are closed by a cable system operating off a wheel wind deriving power by friction with the trailer tire. The unit is mounted on four 27.00x33 and two 14.00x24 tires on the front axle. The power unit is a 300 hp Cummins engine. Hydraulic power boosts the steering. A straight mechanical drive and friction clutch with 10 speeds is used. Conditions Not Ideal Top performance of the truck can be expected only under the conditions for which it was designed, in particular grades under 5 pct, handling fine material, and dumping where one thin layer can be placed on top of another. The machine will handle 42 tons per haul, operating at high speed, with only seconds used for dumping. On a 2 or 3 pct grade over a one mile haul,

Jan 1, 1952

By S. F. Ravitz

IN his excellent book on the Principles of Flotation, Wark' makes the following significant statement concerning the theory of flotation: Two questions of first-rate importance must be considered . . . First, it must be decided whether the sulfide minerals require a collector in order that they may float, or whether as has been claimed, they possess an inherent floatability and need no collector. Second, it must be decided whether the xanthate type of collector can react with or be adsorbed by the unchanged sulfide minerals themselves, or whether, as many claim, reaction with the collector is dependent upon initial oxidation of the mineral surface. In the theory of flotation there are no two questions of greater importance than these. Ravitz and Porter' presented evidence that galena can be floated without a collector, and even without any reagent, provided oxidation products are thoroughly removed from its surface. They found also that thoroughly cleaned galena floated faster when xanthate was used than when a frother alone or no reagent was used, and that, without a collector, the recovery decreased gradually upon exposure of the mineral to air. Their work, however, has met with considerable criticism. I(127).3-6 This paper is presented to answer the objections that have been raised, and to present additional data that confirm their results. EXPERIMENTAL PROCEDURE The apparatus used to provide oxygen-free conditions for flotation has been described in detail by Ravitz and Porter. An atmosphere of purified nitrogen was maintained within the apparatus; all water and solutions used were freed of dissolved air, and could be transferred where desired by the use of nitrogen pressure; nitrogen was used as the gaseous medium for flotation. The flotation cell was essentially a glass cylinder 15 cm. long and 4.6 cm. in diameter. Near the bottom was sealed a fritted glass filter, which broke up the gas into small bubbles, and 6 cm. above this filter was a side arm through which the froth overflowed. The pulp was agitated by a glass impeller, which entered the cell through a mercury seal. For each test 17 grams of galena and 75 ml. of water were placed in the cell, after which the speed of the impeller and the rate of gas flow were adjusted. Water was added gradually during the test to keep the froth level at the proper height. The mineral was prepared and cleaned in the following manner. Exceptionally pure galena was crushed by hand on a clean bucking board, screened to - 150+ 200 mesh, and deslimed on a zoo-mesh sieve with a fine spray of water. It was then boiled on a hot plate for a number of hours with several changes of the desired cleaning solution, after which both the solution and the mineral were placed in the "mineral flask" of the apparatus. The cleaning solution was drained off, and the mineral was boiled with oxygen-free water

Jan 1, 1940

By David W. James

DURING a recent investigation of the transition from a planar to a nonplanar solid/liquid interface for the systems H20-NH4F and 0-AIR,' an apparatus was developed which enabled the morphology of the ice-water interface to be examined during the transition. The slightly curved interface was viewed at a glancing angle with a Bausch and Lomb X30 stereomicro-scope. The interface was obliquely illuminated by a polarized light source. It was thus possible to differentiate between small projections or depressions at the interface, both by a shadowing effect and by the way in which they distorted the colored interference fringes across a particular crystal surface. Many attempts were made to photograph the various stages of interface breakdown. Unfortunately, the limited depth of focus of the microscope rendered the system unsuitable for photographic recording. Visual examination, however, was facilitated by continuous adjustment of the microscope focus control. The following observations of the interface transition were recorded for dilute solutions of ammonium fluoride in water. They are compared with iller's postulated morphologies shown in Fig. 1. i) The initial departure from planarity was characterized by the appearance of a large number of small depressions or "pores" in the interface. ii) The pores were arranged in wavy rows all lying roughly in the same direction within a particular grain. iii) The pores did not appear to form near to grain boundaries. iv) The pores appeared in certain grains before others. v) The transition from the pore structure to the elongated cell structure, Fig. l(d), was difficult to follow. It occurred quite rapidly and no truly irregular cell structure, Fig. l(c), was noticed. vi) The elongated cells gradually became more uniform in size and shape, with straight cell boundaries. They remained elongated, however, and no regular hexagonal cells were observed, cf. Fig. l(e). Several conclusions may be drawn from these observations. Firstly, the appearance of a poxed or, more accurately, a pore structure can be used as a criterion for the onset of constitutional supercooling. Care should, of course, be taken to distinguish between the true pore structure and artifacts caused by splashed-back liquid, particles of oxide, or inefficient decantation of liquid retained between cell boundaries, as described by Spittle et al? Secondly, and contrary to the suggestions of Tiller el l., it seems that interfacial perturbations are characterized not by curved projections but by small depressions or pores. A recent independent investigation by Biloni, Bolling, and cole5 reported in this issue indicates that the depressions might be explained in terms of dislocations intersecting the solid/liquid interface. It is possible that the dislocation concentration is reduced in the vicinity of grain boundaries. This would then explain the grain boundary depleted areas noted in (iii) above. This work was partially supported by the Air Force Office of Scientific Research, Contract No. AF 49-(638)-1029.

Jan 1, 1967

By R. L. Rickett, W. C. Leslie

The influence of deoxidation practice, prior thermal history, and aging time and temperature on the strain-aging behavior of low-carbon open-hearth steels was investigated. The criterion of aging employed was the increase in yield strength in the tensile test, after straining and aging. Composition, prior heat treatment, and aging conditions were all found to be important in governing the strain-aging characteristics of these steels. THAT deoxidation changes the strain-aging propensities of low-carbon steels has been known for a long time, but there has been little agreement, and even contradiction, between results obtained by different investigators and between results obtained in the laboratory and in the mill. This investigation was begun in the hope that some of the uncertainties connected with the strain aging of commercial steels could be eliminated. In considering this problem, it was necessary to define strain aging and to examine the methods used to measure this property. Strain aging can be defined as the changes in properties of a metal or alloy with time, after cold working. The rate at which these changes occur increases as the temperature is raised above atmospheric. The requisite plastic strain is the principal distinction between strain aging and quench aging, the latter being due to precipitation from supersaturated solid solution. Strain aging is also characterized by rapid attainment of maximum hardness at high aging temperatures and lack of softening (overaging) at low aging temperatures. Several possible criteria of strain aging have been listed by Sachsl and by Davenport and Bain.' Because changes in mechanical properties are the most easily measured and the most commonly used, consideration of methods to be used in this investigation was confined to three tests: tensile, notch-impact, and hardness. Hardness tests are the most economical and easiest to perform, but produce only one measure of strain aging. Also, as pointed out by Felmly, Hartbower, and Pellini,³ hardness changes due to aging are not pronounced for steels containing more than 0.15 pct C. Notch-impact tests require careful preparation of large numbers of specimens. Above and below the transition temperature the test lacks sensitivity; furthermore, it is extremely difficult to impart a uniform strain to the specimens, followed quickly by aging and final testing; machining must generally take place after straining. For these reasons, the tensile test was selected for use. Although this test requires a considerable expenditure of time, labor, and money in preparation of the specimens and performance of the test, more information can be gained than from any other single mechanical test, information which includes upper and lower yield points, yield-point elongation, tensile strength, strain-hardening exponent, reduction of area, and elongation. Low and Gensamer' and Schwartzbart and Low5 lso used the tensile test, taking the increase in flow stress after straining in tension and aging as a measure of strain aging. In our work, as in theirs, each specimen was strained an arbitrary amount, sufficient to pass through the

Jan 1, 1954

By Ronald J. Roman

Research pertaining to flow of solutions in leach dumps has generally been neglected. This technical note proposes a method for evaluating the flow patterns and incorporating the results into dump-leaching models. Three dump-leaching models1-3 have been proposed to scale up laboratory test data to expected field results. These models are based on the same physical picture in a dump and differ only in the importance of diffusion or surface chemical reaction rate. Selection of this rate-controlling phenomemon is based on type of ore (sulfide or oxide), physical dimensions of the particles being leached, and the leach heap itself. All three models are applicable to specific types of operations. The models are similar in the use of a size distribution analysis for the dump material and the assumption that the leach solution flows around each particle. Transport of the leaching agent to the interior of the particle takes place by diffusion [(Fig. 1)]. However, normal dumps are of a higher bulk density than the material in a laboratory column used to generate the scale up data. How does this difference in bulk density affect the scale up equations? Increasing the bulk density can be expected to give more particle-to-particle contact; therefore, individual particles will be blinded by each other. As blinding increases with bulk density increase, the particles will behave like larger particles with a coarser apparent size distribution. The extreme will occur when the bulk density reaches that of the undisturbed rock, the entire dump behaving as a single particle with the dimensions of the heap itself. Harris4 alluded to this phenomenon in his paper. An alternative method of describing the same phenomemon is to consider the flow paths of the solution. At high bulk densities leach solution no longer surrounds each particle, but flow paths are separated by several particles and channeling is said to take place. Instead of the particle radius being the maximum distance through which the leaching agent must diffuse, the maximum distance is half the separation distance of the solution flow path. Particle size distribution must then be replaced in the models by the concept of channel separation distribution. Like size distribution, channel separation distribution specifies the cumulative percentage of the rock in the dump situated less than a specified distance from a solution channel. Thus, [ ] Distribution of the solution channels is a function of how the dump was built (among other things), and therefore it cannot be determined in the laboratory. Accordingly, it becomes necessary to determine a range for d and a in existing operations or measuring these parameters before leaching starts. Howard5 gives a clue to one possible technique of measuring solution channel distributions. When his paper was published little was known about the phenomemon of leaching; the importance of this type of data was not recognized. [Fig. 2] is a Y-Y log for one hole drilled

Jan 1, 1978

By Harry Udin

IN 1948, the writer and his associates determined the surface tension of solid copper by balancing the force of surface tension in a very fine wire against an external load.' At that time we, in common with other early workers, assumed that grain boundary energy in a pure metal is very small in comparison to the energy of an external surface. Accordingly, we neglected the internal surface energy of the coarse-grained specimens. Since that time, experimental evidence has accumulated showing that grain boundary energy, far from being small, is generally about one-third of the energy of an external surface.2-4 This is sufficient to introduce a significant error into our determination. The differential equation governing equilibrium is: wdl - yds, + y*ds2 [I] rather than wdl = yds as originally written. w is the balancing force in dynes, 1 the length of the specimen, sl the external and s2, the internal surface area, y the copper/ copper vapor surface tension, and y* the grain boundary tension. Fortunately, we had made for another purpose a careful study of the size and shape of the grains, and found that the boundaries, with rare exceptions, traversed the specimens and were perpendicular to the wire axis. For this case, eq 1 leads to w = rry -(n) r2y* [2] where r is the wire radius and (n is the number of grains per unit length. A count of some twenty 5-mil wires indicated that - n became 80 & 10 after a short anneal near the melting point, and remained nearly constant for as long as 96 hr at temperature. An assumption of y* = 1/3y leads to a defining eauation for r: [31 The term in the brackets may be considered a correction factor applied to eq 11 of ref. 1. Upon applying this factor, the surface tension of solid copper at its melting point is found to be 1650 & 100 dynes per cm, rather than 1370 as previously reported.' The new temperature coefficient is —0.55 dynes per cm per "C. Grain boundary energy is more significant than surface energy to the physical metallurgist. It is evident from eq 2 that a series of experiments with wires of different grain size can lead to an evaluation of y*. The details of such an experiment are being worked out now. References 1 H. Udin, A. J. Shaler, and J. Wulff: The Surface Tension of Solid Copper. Trans. AIME, 185, 186-190; Journal of Metals (Feb. 1949) TP 25303. 2 G. L. C. Bailey and H. C. Watkins: Surface Energies in the System Solid Copper-Molten Lead. Proceedings Physical Society. (London) (1950) 36B, 350. 3 L. H. VanVlack: Inter granular Energy of Iron and Some Iron Alloys. Ph.D. Dissertation, Univ. of Chicago, Sept. 1950. 4 . P. Greenough: Grain Boundary Energies in Silver. R.A.E. Report, No. Met. 52. (May 1950) Fan-borough, Hants, England.

Jan 1, 1952

THE second part of the mould for making guns is the core. Without this the space could not be made where the powder is to be and through which the ball, impelled by the fire, can pass and take flight. To make this it is necessary to take two things into consideration, because they are very important. One is what you are to make it on so that it may be supported and kept true. The other is what composition of clay will stand up during casting and yet not be very difficult to extract from the body of the finished gun. For the first, it is found that only an iron spindle of a suitable thickness is able to support the weight of the clay without bending under the heat of the fire or wobbling as it is turned on its journals or when handled. This should be a braccio or more longer than the mould of the gun and worked exactly round, straight, and well tapered like a spindle; above all every one of its joints should be well secured and solid. At the upper end a per-orated heel should be made, and lower down, exactly at the point corresponding to the length of the mould, are one or two other holes through which the little crossbars can be passed that fasten the core to the outer mould and also serve for constructing the disc. Now this iron is to be arranged on two trestles, pivoted so that it may turn truly when rotated. In order that it may not run up and down, make a little iron fork which engages a notch made with a file at the foot, and another at the head. After this, you must prepare clay for the core which is well made and tenacious ,enough not to crack. Fint take care that there are no pebbles in it and that it is composed of a small amount of cloth clippings and much sifted horse dung and some washed and clean wash ashes so that it may be of a tender and crumbly consistency in order that it may later be more easily extracted from the space inside the gun. In the same way, in order that you may be able to take out the iron piece at the same time, first cover it with ashes, and then wrap it all over with a rope of ordinary thickness, leaving a dito of the iron uncovered in every palmo length. [86] Alternatively, you may cover it all very tightly with hemp tow in the same way after it has been covered with ashes. Or heat your iron considerably and then cover it all to the thickness of a good cord with wash ashes or powdered charcoal that has been made into a paste with a little

Jan 1, 1942

By William A. Johnson

The fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems; but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state.l-3 It is doubtful that this mechanism can ever be directly ascertained; rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected. Because of its relative simplicity, diffusion in a system containing only one kind of atomic species—commody called self-diffusion—is of considerable theoretical interest. It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments—of which diffusion in a chemical concentration gradient and self-diffusion are two important types—are carefully performed and inter-compared. Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance. The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data.† Self-diffusion implies the diffusion of something into its exact counterpart; the detection of such a process is patently impossible, and it is necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element. There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties; neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon. In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atom down its chemical concentration gradient. The first measurements of self-difiusion were made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead. The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7, 8 copper,2, 9 and zinc.10, 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness; it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves. The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By E. A. Nichols

The purpose of this paper is to present a contour map that shows the geographical variation in geothermal gradients in the Mid-Continent and Gulf Coast oil fields. Introduction Frequently there arises the need for an estimation of the temperature to be expected at a predetermined depth in working with a wildcat or in deepening old production into 'Ones that are relatively unknown. The study of geothermal gradients in oil fields has been made previously by many investigators. One of the pioneers in this work was C. E. Van Orstrand,' who, as well as most of the other investigators, was primarily interested in the relation between temperature and depth in a given locality. Between 192r and 1929, American Petroleum Institute Research Project NO. 25 fostered a thorough study of earth temperatures.2 K. IV. French did some work in California, the results of which were published in 1939.3 In most of these studies, an attempt was made to correlate temperatures in a rather localized area. This paper will show the results of an attempt to correlate temperature gradients over rather large Portions of the Mid-Continent and Gulf Coast area. Method of Obtaining Data It has been found that for complete thermal equilibrium to be established in a well, the well must stand undisturbed for a period of several hours to several weeks, depending upon the way the well was produced prior to the shut-in period. The data in this paper were obtained in conjunction with running pressures in wells or in taking samples of reservoir fluid. Glass maximum recording thermometers were used in all but a few instances. The wells had been shut in from one hour up to I. or 12 days. Since the wells were normal producing wells, some of the shut-in times undoubtedly were insufficient for complete thermal equilibrium to have been established and the temperatures measured do not necessarily represent the true earth temperatures. They do represent the temperature conditions that will be encountered in a well that is producing oil. The data, therefore, can be useful in working with or in estimating the temperatures to be expected in producing reservoirs. In obtaining a thermal gradient by dividing the difference in temperature of the formation and the mean annual surface temperature by the depth of the formation, one is assuming the depth-temperature line to be straight. Depth-temperature curves are almost straight lines (Fig. I). However, on close examination of accurate data, a slight curvature usually is observed. Most wells yield curves with slopes increasing with increasing depth. These curves are believed to be from wells that are in and are underlain by sedimentary material. Some few curves have slopes that decrease with increasing depth. These curves are believed to be from wells that are underlain rather closely by granite or some other igneous rock. Most investigators

Jan 1, 1947

By L. S. Chabot

The bibliography of mining methods in the past few years has contained many articles dealing with the use of the diamond drill for blasthole drilling. In the Canadian mines, this method has been used with great success in stoping at Noranda, Aldermac, Waite Amulet, East Malartic and Sladen Malartic mines in the Province of Quebec. It has also been used at the Dorchester and Beattie gold mines in Duparquet, Quebec. The method has found useful application at Copper Mountain mine, British Colombia, and at Flin Flon mine in Manitoba. In the United States, the diamond drill blasthole method has been used at Cornwall Iron Ore Mines in Pennsylvania and at the Republic Steel Corporation magnetite properties in the Port Henry district of northern New York. In the Lake Superior iron district, the method has been used at the Anvil-Palms mine of Pickands, Mather and Co. at Bessemer, Mich., and is also used at the Book mine of the North Range Mining Co. at Alpha, Mich. Other companies in the district have also experimented in some degree with the method at some of their properties. This Paper is being offered as a prelimi- nary report on the use of the diamond drill method of stoping at the Book mine. Sufficient work has been done with it to prove its worth and it is the purpose of the article to present some results, operational details, equipment ideas and recommendstions which we have found in its use at our mine. Location and Description The Book mine is situated about a mile north of the village of Alpha, in the NE-NE1/4 and the SE-NE1/4 of set 12-42-33, between the Dunn mine and the Balkan-~~d~~~ mine, and about four miles southwest of the village of Crystal Falls, on the menominee Range of Michigan, The property was found to have ore near surface in sufficient quantities for open-pit operations and stripping was begun in the latter part of 1942 to prepare it for ore production in 1943. During 1943, 288,447 tons of direct shipping ore were produced from the open pit and 382,933 tons in 1944 While the mine was being operated as an open pit some 350,000 tons of lean ore were stockpiled for later treatment. This material is beilng treated in a washing and jig plant and concentrates are produced during the shipping season. The ore bodies at the Book mine are characteristic of the Menominee Range. They are found on the flanks of sharply folded anticlines which have a fairly steep pitch to the northwest. The open-pit operatiOns in 1943 and 1944 revealed two of these anticlinal structures. A detailed study and classification of the old diamond drill records, coupled with the information of some new holes drilled, has established the

Jan 1, 1949

By G. B. Craig, G. L. Montgomery

A simple technique has been developed which reveals glide dislocations in zone-refined aluminum as etch pits. The technique has been tested quantitatively by making dislocation counts on aluminum single crystals deformed in pure bending. The method has the advantage of being insensitive to the orientation of the surface under examination. A number of etchants which will reveal dislocations in annealed aluminum have been reported.'-' These etchants apparently depend on decoration of the dislocations by an impurity (probably iron) and cannot, therefore, be used to reveal fresh glide dislocations. In addition, it is unlikely that screw dislocations will be etched because of their small attraction for impurity atoms. Amelinckx6 has reported that glide dislocations located along slip traces can be revealed by fluo-rated aqua regia. This work indicated that dislocations themselves, irrespective of decoration by impurity atoms, are responsible for the etch pits. However, as a result of additional etching experiments, Wyon and Marchin7 concluded that dislocations alone are not sufficient to explain the localization of etch pits on slip lines in aluminum using chemical etch-pitting techniques. In addition, their results show that glide dislocations are revealed only on surfaces approximately parallel to a (100) axis and that not all slip systems are attacked. These observations have been confirmed by the present authors. The technique described in this article is insensitive to the orientation of the surface, and reveals dislocations on all glide systems. Fig. 1 shows a deformed region in the neighborhood of a scratch. Dislocations can be seen along three slip traces. In the present work, single crystals of zone-refined aluminum are polished for from 2 to 5 min in a chemical polishing reagent held at 100°C, as described by Herenguel and second:' H2Sol 60 pct H3PO4 30 pct HNO3 10 pet The samples are then coated with a thin oxide film by annealing in air at 450°C for 1 hr and cooling in the furnace. After deformation, dislocation etch pits are developed by immersing the specimen in the same polishing solution which is now held at a temperature of 50°C. The formation of small hydrogen bubbles indicates that etching has occurred. The sample is immediately removed from the solution. Prolonged etching results in enlargement of the pits and, in regions of high dislocation density, the overlapping and loss of resolution of individual pits. It is the experience of the authors that contact with iron will ruinously contaminate the reagent. With careful etching, dislocations separated by half a micron can be resolved optically and the method has been shown to be sufficiently sensitive to reveal dislocations produced during the pre-easy glide region of deformation, Fig. 2. A few examples of glide-dislocation configurations, as revealed by this technique, are shown in Figs. 1 to 4.

Jan 1, 1964

By George A. Morrison

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

Jan 1, 1948

By E. A. Nichols

The purpose of this paper is to present a contour map that shows the geographical variation in geothermal gradients in the Mid-Continent and Gulf Coast oil fields. Introduction Frequently there arises the need for an estimation of the temperature to be expected at a predetermined depth in working with a wildcat or in deepening old production into 'Ones that are relatively unknown. The study of geothermal gradients in oil fields has been made previously by many investigators. One of the pioneers in this work was C. E. Van Orstrand,' who, as well as most of the other investigators, was primarily interested in the relation between temperature and depth in a given locality. Between 192r and 1929, American Petroleum Institute Research Project NO. 25 fostered a thorough study of earth temperatures.2 K. IV. French did some work in California, the results of which were published in 1939.3 In most of these studies, an attempt was made to correlate temperatures in a rather localized area. This paper will show the results of an attempt to correlate temperature gradients over rather large Portions of the Mid-Continent and Gulf Coast area. Method of Obtaining Data It has been found that for complete thermal equilibrium to be established in a well, the well must stand undisturbed for a period of several hours to several weeks, depending upon the way the well was produced prior to the shut-in period. The data in this paper were obtained in conjunction with running pressures in wells or in taking samples of reservoir fluid. Glass maximum recording thermometers were used in all but a few instances. The wells had been shut in from one hour up to I. or 12 days. Since the wells were normal producing wells, some of the shut-in times undoubtedly were insufficient for complete thermal equilibrium to have been established and the temperatures measured do not necessarily represent the true earth temperatures. They do represent the temperature conditions that will be encountered in a well that is producing oil. The data, therefore, can be useful in working with or in estimating the temperatures to be expected in producing reservoirs. In obtaining a thermal gradient by dividing the difference in temperature of the formation and the mean annual surface temperature by the depth of the formation, one is assuming the depth-temperature line to be straight. Depth-temperature curves are almost straight lines (Fig. I). However, on close examination of accurate data, a slight curvature usually is observed. Most wells yield curves with slopes increasing with increasing depth. These curves are believed to be from wells that are in and are underlain by sedimentary material. Some few curves have slopes that decrease with increasing depth. These curves are believed to be from wells that are underlain rather closely by granite or some other igneous rock. Most investigators

Jan 1, 1947

By P. H. Cardwell

The effect of various plastics upon the permeability of a sand and the mechanism of their ensuring permeability within the consolidated sand body is discussed. Data are presented on various properties of the plastic materials used in sand consolidation and the effect of temperature and usable temperature ranges are considered. The recovery of petroleum from uncon-solidated sands presents serious production problems, owing to sloughing of the formation. The solution of some of these problems usually has been by mechanical methods.' The ideal way of controlling the sloughing tendencies of these un consolidated formations, however, is to prevent the movement of the individual sand grains by the use of a bonding medium. A step in the desired direction was taken by Irons and Stcesser2 when they taught the use of liquid plastics to produce a consolidating deposit that prevents sloughing. More recently, Wrightsman and Buckley3 proposed a modification of this process. In this use of the liquid plastic, the sand grains become coated and the ensuing hardening of the plastic by polymerization or condensation cements together the sand Particles. Liquid plastics that have been suggested for this Purpose are of the following types: phenolformaldehyde, alkyd resins, vinyl type resins, polystyrene and the acrylic esters. When the flow of fluids through a sand must not be materially reduced, it is essential only to cement together the sand grains with liquid plastic and leave a portion of the interstitial space for fluid flow. TO be assured of obtaining fluid flow through the sand interstices after injection of plastic, it has been necessary in the past to remove the excess plastic from the interstices between the particles before it sets. Wrightsman and Buckley suggest two methods for the removal of the excess plastic from the interstices of the sand: (I) to flush the excess plastic back into the formation, away from the well bore, by use of oil or water; (2) to produce the well before the plastic has set, thereby moving the excess plastic into the well bore. Under certain well conditions it is very difficult to remove the excess plastic from all parts of the formation by either of these methods and leave the formation consolidated with no sections completely sealed. The method* described herein of retaining permeability within a sand body is to use a liquid plastic that upon setting ensures permeability within the consolidated sand body. This cements the sand grains but obviates the need for removing plastic from the interstices of the sand. One of the ways of accomplishing this is to use a liquid plastic that occupies a considerably greater volume than the solidified resin it yields on further polymerization or condensation in situ. In order to be satisfactory, the volume of the plastic while liquid should be at least one and one half times the volume of the solid formed. Preferably,

Jan 1, 1947

By Louis Huntoon

HISTORY of the Porcupine area has been pub-lished in detail by the Ontario Bureau. of Mines in several issues of its annual reports. An. interesting volume could be written on: this topic; especially if personalities were introduced, such as the. transaction whereby the original title to the Hollinger group of claims was settled between Ben Hollinger and Alex Gillies by the toss of a coin. The early history of the McIntyre mine also had its thrilling events, such as its manager, R. J. Ennis, dodging the sheriff and deposit-ing red-hot gold bricks in the bank to meet his pay-roll. The occurrence of quartz veins containing low gold values was reported in 1896 by E. M. Burwash and again in 1899 by W. A. Parks. The first application for a mining claim appears to have been applied for on Dec. 30, 1906, by W. 0. Taylor, of Toronto, one of the old employees of the Hudson Bay Co. On the recom-mendation of Mr. Taylor, early prospecting was done on the shores of Porcupine Lake. It. was not until the spectacular discovery of the surface croppings at the Dome mine, by J. S. Wilson in 1909, that a rush to the district took place. Exploration was carried on during 1910 and 1911. The big boom was on in 1911, when claims sold on the evidence of mere rock croppings, owing to the prevailing heavy overburden. Rock croppings with specks of gold brought big prices. The country was heavily timbered and most difficult to prospect. My first trip was made during the summer of 1911, while the railroad was under construction from Porquis Junction to South Porcupine. I published my observations in the Canadian Mining Journal, Dec. 15, 1911, discussing in particular the character of the ore deposits and the future prospects of the camp. The first mills were erected in 1911, only to be destroyed by the disastrous fire in July of that year. They were rebuilt and the first important shipments are recorded in 1912. The history of the camp from the discovery of the Dome to the present consists of alternate chapters of great optimism and those of a more non-committal nature. For the engineer unfamiliar with the character of the deposits of this area, and the north country in general, it is at times most difficult to draw conclusions and submit definite recommendations. When valuable orebodies apex at depth, with no surface showings other than slightly mineralized veins of quartz or quartz containing a little visible gold; when at depth valuable veins and ore deposits, paralleling the one being explored, are developed by cross-cutting, such as Nos. 85-58 on the Hollinger, which have been its largest producers, the engineer assumes responsibilities rarely called for in other mining districts. This fluctuating aspect is exemplified in the three large producers, and may be duplicated with some of the old producers now being explored.

Jan 8, 1923

WHILE papers on cleaning coal and mining coal were presented at the iron and steel and mining methods sessions, respectively, the first general session on coal was held on Wednesday afternoon. Howard Eavenson of Pittsburgh, Pa., as chairman of the session,* reported progress by the Committee on the Valuation of Coal for Blast-Furnace Coke. A paper on blasting coal effectively and safely in Southern Illinois, by J. E. Tiffany and S. S. Lubelsky, was abstracted and commented on by Dan Harrington, of the U. S. Bureau of Mines. W. J. German commented on some conditions mentioned in the paper as unsafe or bad practices, and added to these some further ex-amples; he made a strong plea for holes to be: drilled parallel to the bedding as the easiest way to determine the proper length or depth to agree, with the depth of kerf cut. Mr. Barron called attention to proper cutting and-drilling and rate of detonation of the explosive used, as effective aids in blasting coal. Another speaker mentioned an odd case where compressed black powder or "pellet powder," had decreased accidents at a non-gaseous mine where permissible explosives had been formerly used; the permissible cracked or shattered the roof, with a resulting high accident rate from falls of roof, and pellet black powder overcame this trouble. Eugene McAuliffe of the Union Pacific Coal Co. told of difficulties in changing from black powder to permissible in Wyoming mines. J. B. Dilworth read a paper on valuation of coal prop-erties, expressing a preference for the method of capi-talizing the earning power of a property. Eli T. Con-ner of Scranton, Pa., with much experience in valuation work, stated that the method was undoubtedly good, but many times failed because of inability to forecast accurately future earnings, and further contended that total valuation -and royalty rates could generally be fixed fairly when based on similar neighboring proper-ties' rates when these had recently been established by a free bargaining. S. A. Taylor of Pittsburgh, Pa., stated that a leasehold value could be fairly established by figuring based on 10 to 20 per cent of the profit resulting from operation. The chairman read a written discussion from Henry Louis of England, called atten-tion to differences in valuation resulting from whether gross or net profit or earnings were used as a basis for capitalizing. John A. Garcia of Allen & Garcia gave a most inter-esting account of coal mining and general conditions in Russia as noted in his recent extensive visit there, which appears elsewhere in this issue. Although agree-ing with most thinking Americans that government operation is incompatible with progress, he showed that mining conditions were far from impossible in present-day Russia. Charles E. Stuart gave motion pictures of parts of the trip, with, his own comments supple-menting those of Mr. Garcia.

Jan 3, 1928

By H. S. Cannon, F. N. Rhines

The application of a static load to a copper powder compact during sintering at an elevated temperature accelerates the rate of sintering in such a way that a given load induces the same proportional increase in rate for all times of sintering. It is shown that sintering under a load is like creep under a fixed load in that the stress required to accomplish a given degree of densification is proportional to the logarithm of the sintering time. VIRTUALLY all of the theories of sintering that have been put forward within recent years have contained the assumption that the chief driving force of the process is the surface tension resident in the exposed surfaces and internal pores of the compact, or powder mass. An externally applied load might be expected to provide a somewhat equivalent driving force for sintering. It is known that the application of a compressive load, during sintering, hastens densification, but it is by no means clear whether sintering under the influence of surface tension alone and sintering under an applied load are fundamentally similar processes. The present study was undertaken in an effort to obtain an answer to this question and with the hope that the answer may contribute to an understanding of the mechanism of sintering. It has been found that there is a close relationship between sintering and creep processes. Copper powder compacts were sintered in hydrogen at 1000 °C under dead loads of 0 to 165 psi and the progress of sintering was observed by means of density measurements. Using a commercial reduced oxide copper powder, see Table I, cylindrical compacts Yz in. x x in. high were made at a pressure of 12,500 psi. For sintering, these were placed in a cylindrical graphite container into which they fitted snugly. A compressive axial load was applied to the compact through a graphite rod of similar diameter, which rested upon the upper end face of the compact; iron weights, in suitable amount, were placed upon the graphite rod to provide the load. This assembly was encased in a vertical silica tube within a resistance-type furnace capable of maintaining a substantially constant temperature within the working zone. After various predetermined times at temperature, the samples were removed from the furnace and their density was measured by conventional means. The heating-up and cooling-down times have been included in the computed sintering time, using the assumption that the sintering rate doubles for each increase of 10 °C in temperature. The experimental results are presented in Table 11. Upon metallographic examination of the specimens, it was found that there was no apparent change in the shape of the pores as a result of loading, i.e, no flattening, Fig. 1. Substantial contraction away from the container walls was observed in all samples sintered with loads of 10.5 psi and less.

Jan 1, 1952

By R. J. Walter, W. T. Chandler

The Ch-H phase diagram was determined for by-drogen concentrations up to ChHo.9 at temperatures below 400°P'. The phase diagram includes a mis-cibility gap and a eutectoid transformation. A peri-tectoid transformation is postulated at the hydrogen-rich end of the diagram, Phase diagrams were determined for two levels oj purity, of the columbium. A single solid solution exists in the Cb-H system above 400°F. There has been considcrable disagreement among investigators concerning the system at temperatures below 400°F. Albrecht, Goode, and ~allett' proposed a miscibility gap containing two bcc phases with the two lattice parameters converging at about 140°C (285-F), and Brauer and ~erman' found a two-phase room-temperature region between 10 and 41 at. pct H. At sufficiently high hydrogen concentrations in the one-phase region, the hydrogen-rich phase was found to be face-centered orthorhombic. Wainwright, Cook, and Hopkills3 recently reported that the face centered orthorhombic hydride phase is derived from a unit cell which is slightly tetragonal with a small departure from 90 deg of the angle (y) opposite the r axis. The orthorhombic hydride phase was observed for hydrogen concentrations between 0.2 and 0.8 H/Cb atom ratio. Paxton and coworkers4 found that needlelike hydride plates formed in a hydrogen-charged columbium single crystal and suggested that this transformation possessed the characteristics of a diffusionless phase transformation. On the basis of room-temperature, X-ray diffraction data, komjathy' suggested that an order-disorder or martensitic transformation occurs. In the present study, the Cb-H system was investigated to resolve the discrepancies found in the literature for this system. PROCEDURE The columbium specimens were prepared from two heats of wrought 1/2-in.-diameter electron-beam melted columbium rod and from two columbium powders of -80 mesh size of different impurity contents. The columbium bar stock was pur chased from Urah Chmg Corp.; the 99 and 99.5 pct purity colulnbium powders were obtained from Fansteel Metallurgical Corp. and Kern Chemical Co.. respectively. The chemical analyses of the columbium bar and powders are listed in Table I. Hydrogen charging was performed by exposing the columbium specimens to hydrogen at 1 atm pressure at various temperatures. After exposure the specimens were quenched to prevent the hydrogen pickup which would take place if cooled in hydrogen, or the hydrogen loss that would occur if cooled in an inert gas. Adequate hydrogen purity was achieved by passing high-purity tank hydrogen (maximum 5 ppm total impurities) through an Engelhard catalytic Deoxo unit, magnesium per chlorate desiccant, and finally through activated charcoal at the temperature of boiling nitrogen. Activated charcoal at -321°F has been reported6 to remove impurities from hydrogen to a nondetectable level. A schematic representation of the heat-treating apparatus is shown in Fig. 1. A metal-sheathed thermocouple embedded in the colun~bium specimen was used to control the temperature during heat treatment and to pull the specimen boat into

Jan 1, 1965

By William A. Johnson

The fundamental role of diffusion in many reactions occurring in solid metals has long been recognized, and there have been careful measurements of rates of diffusion in numerous alloy systems; but our understanding of the atomic mechanism by which diffusion occurs is scarcely in an advanced state.l-3 It is doubtful that this mechanism can ever be directly ascertained; rather, all imaginable mechanisms must be examined and the one that is in best accord with such data as can be obtained from suitably chosen experiments should be selected. Because of its relative simplicity, diffusion in a system containing only one kind of atomic species—commody called self-diffusion—is of considerable theoretical interest. It may be expected that diffusion theory will not be advanced appreciably until a wide variety of diffusion experiments—of which diffusion in a chemical concentration gradient and self-diffusion are two important types—are carefully performed and inter-compared. Aside from the purely theoretical interest in self-diffusion measurements, such studies will be of considerable engineering importance. The rate of any process in a pure metal requiring the movement of atoms, of which recrystallization and creep are two familiar examples, will be understood more readily with the aid of self-diffusion data.† Self-diffusion implies the diffusion of something into its exact counterpart; the detection of such a process is patently impossible, and it is necessary to substitute for it the diffusion of one isotope (in this case radioactive) into another isotope (in this case stable) of the same chemical element. There is, however, no reason to suppose that a radioactive atom will not diffuse at the same rate as its stable isotope, for all of the isotopes of the same element have exactly the same chemical properties; neither the difference in nuclear energy nor the difference in mass would be expected to exercise an important influence in this phenomenon. In this sense, self-diffusion may be thought of as the diffusion of radioactive atoms down a radioactivity concentration gradient, just as usual diffusion is the diffusion of one kind of atom down its chemical concentration gradient. The first measurements of self-difiusion were made by von Hevesy4-6 using the radioactive lead isotope thorium B in ordinary lead. The recent development of means for producing artificial radioactive elements has made possible similar measurements on gold,7, 8 copper,2, 9 and zinc.10, 11 Many of the data that have been obtained are rather poor, and no adequate reason has been given for their poorness; it appears, however, that the unsatisfactory results are characteristic of the particular experimental procedure employed, and not of self-diffusion measurements in themselves. The experimental technique that has yielded the poorer results is the deposition of a thin layer of radioactive atoms on the surface of a specimen and the determination of the rate of inward diffusion

Jan 1, 1941

By J. G. Benford, E. B. Stanley

THERE have been numerous papers in the literature1 on the subjects of secondary and tertiary recrystalli-zation in silicon steels. Secondary re crystallization is believed to occur in silicon steel by either a surface-energy phenomenon such as in the usual development of cube texture or by a second-phase phenomenon such as in the usual production of cube-on-edge texture, (110)[001]. Tertiary recrystallization in silicon steel is thought to be a surface-energy phenomenon in which, for example, grains having a (110) plane parallel to the sheet grow at the expense of other grains in the matrix including those having a (100) plane parallel to the plane of the sheet. In all these instances, the orientations involve either a preferred (100) or (110) plane in the plane of the sheet. Until very recently, there had been no experimental evidence reported of the occurrence of a texture by secondary or tertiary recrystallization that involves a (111) plane in the plane of the sheet, although Kohler reported that grains having the (111) plane parallel to the sheet surface can also grow by a surface energy mechanism. Stickels observed a secondary texture in iron described as "near {554}(225)" about 5 deg from {lll}(211).3 Mee reported that in a vacuum-remelted commercial 3 pct Si steel {lll}(hkl) secondary recrystallization took place in a high vacuum and in pure hydrogen.4 Recently in our Laboratory, large-grained structures such as shown in Fig. 1 having an orientation near (111)[211] or (111)[2ii] have been observed. The arrows point to areas of relatively small matrix grains of the kind that the much larger (111) grains consumed while growing. It is of interest that the matrix grains of samples annealed at 2000°F were essentially the same size as those in samples annealed at 2200°F, a matrix-grain-size stability that is characteristic of secondary recrystallization processes. A torque disc taken from Grain 4 of the sample shown in Fig. 1 revealed a very flat magnetic-torque curve, as expected, with a maximum torque of 7000 dyne-cm per cu cm compared to the typical 180,000 dyne-cm per cu cm observed for conventional (110)[001] textured material. A back-reflection Laue pattern for Grain 4 is shown in Fig. 2 and indicates a near-perfect (111)[211] orientation. The other six numbered grains in the sample of Fig. 1 had a similar orientation. The small circles next to each number were the target areas for the X-ray beam. The starting material was an 0.011-in.-thick oriented silicon steel, (110)[001] texture, containing 3 pct Si. It was lightly pickled, cold-rolled to 0.005 in., and annealed 4 hr at 2200°F within a nickel box (not gas-tight) inside a tube furnace through which dry hydrogen was flowing. The samples were heated to 1500°F in 1 hr and then at 60°F per hr to 2200°F. There were other

Jan 1, 1969