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P. W. SHIMER, Easton, Pa. (written discussion*).-When lump calcium cyanamid is immersed in the melt of mixed chlorides of the alkalies and alkaline earths in the manner described in the paper, the amount of sodium cyanide formed in the melt, as shown by numerous analyses, is but a small fraction of that formed by the reaction referred to by Mr. Johnson. The case-hardening effects in my process are, however, at least as good as when the common cyanide baths are used. Moreover, when compared with the cyanide baths, the gases evolved in the new process are harmless, consisting of nitrogen, carbon monoxide (which burns to carbon dioxide on the surface of the melt), and occasionally a little carbon dioxide. These gases are not irritating or poisonous, whereas the vapors arising from cyanide baths are both irritating and poisonous. The complex chemical reactions that take place in and on the surface of the melt are being investigated by the writer, who hopes, in due time, to communicate the results of his work.

Jan 7, 1919

By Samuel Lasky

WITH the movement of American capital into foreign investment, a new field of specialization for the American mining engineer is gradually opening a field hitherto entered almost wholly by chance and without full appreciation of its possibilities. Our age has been fitly called the "Age of Specialization." The special application of one's knowledge and ability to a definite and restricted branch of .his profession is purely a modern condition. Any profession, or branch of a profession or, industry, in which the problems may be segregated into definite types, calls for specializa-tion. Modern industry demands efficiency and that, reduction and ultimate annihilation of waste. Effort and time wasted by workers' on a problem with which they are not familiar is as flagrant a waste of money -the final standard-as any waste of materials. One of the subdivisions of mining engineering which is beginning to be recognized is of engineers who are clearly conversant with the particular and peculiar problems obtaining under foreign operating conditions. The need is as yet obscured, however, by the domestic prosperity of our American mining industry. The opportunity here lies more with the American engineer than with other nationals. The foreign en-gineer now in that service is not there through a realiza-tion of the special opportunities that exist, but through necessity, whereas, with the American engineer, more especially ,the recent graduate or those who will soon graduate, this is a new field to be entered wholly by choice. As a matter of fact, many engineering students will find it necessary to seek foreign service if they wish to remain in mining. Although the scope of the domes-tic industry is tremendous and there are many positions open to the junior engineer, there are not enough for the great number of graduates turned out yearly from our, mining schools. Educators tell us that less than 40 per cent. of the students in engineering schools gradu-ate; and of these but a minority continue in engineering. Even this minority is too great for our domestic. In-dustry, and although the young engineer realizes that condition after a few years he rarely seeks foreign work. A. perusal of the directory of the American Institute of Mining Engineers indicates that, but about one-half of one per cent of the Junior Associates are in positions outside of North America. Granting that most of them are still in school, the figure is surpris-ingly small.

Jan 1, 1927

Primarily, 1961 was a year for widespread application of tools and techniques which have become operational in the past several years • • • Raising --Raise climbers and climber raising techniques have been improved; narrow veins as low as 55° dip are now being mined from climber raises. Climber modifications include: larger motors, tighter radius curves negotiated, improved lubrication and new methods of stowing the climber during a blast. Climber raises are now ventilated in several ways: a 12-in. diam flexible vent tube behind the climber rail; a 6-in. diam pipe behind the climber rail (with fan); or a 6 to 8-in. diam drill hole along the axis of the raise. In hot raises, these ventilating techniques have resulted in more rounds per shift. When driving raises from crosscut and lateral development, mucking machine loading of raise rock is preferred over slusher ramp loading for the following reasons: a) faster set-up and teardown of climber facilities; b) easier access for climber maintenance, repair and loading of raising supplies; c) area at the bottom of the raise can be kept cleaner. Both wide and narrow veins are mined from 7 x 7-ft climber raises at Butte and at Republic, Wash. At Republic, climber rollers have been modified to support increased weight when driving 55°dip raises • Drilling-The new largebore, short-stroke push feed drills are much faster drilling than previous models and are most satisfactory in hard ground. Although reports on maintenance studies of the new drills are not yet available, increased steel and bit wear and breakage, and increased drill maintenance are seen as potential problems. Mines in Montana and Idaho continue to test rubber-collared drill steel. The fabricating methods used are successful but advantages in increased steel life have yet to be proved. Underground applications of down-the-hole drills continue. Drilling speed and accuracy are reported as the outstanding advantages. Manufacturers are now hopeful of making drills which will operate in any direction. Present applications are for ventilation holes (to 8 in. diam) for climber raises, holes for hydraulic fill distribution, drain holes and "predrilled" raises. Good drilling accuracy has been reported to a depth of 200 ft. Cutting holes in drifting is seen as a future application

Jan 2, 1962

Discussion of the paper of Earl S. Bardwell, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 79, July, 1913, pp. .1429 to 1441. H. O. HOFMAN, Boston, Mass. (communication to the Secretary*) :-It is pleasing to the originators of the planimetric determination of oxygen in refined copper to see that the method has been taken up by a large smelting plant to be used in every-day work after it has been simplified to suit the new conditions. Several years ago Huntington and Desch 1 had improved our mode of working. They projected the developed negative on to a screen, traced the outlines of the picture with a pencil, drew a border, and measured one constituent with. the planimeter. In order to give the work greater precision, they divided the area into squares of 1 cm. side, shaded the

Jan 11, 1913

By Eugene McAuliffe

The mining press, as well as certain federal and state bulletins, refer from time to time to the relative hazards that attach to loading bituminous coal by hand when compared with the so-called "mechanical loading" process. Much of the coal coming under the head of hand-loaded coal is won in part by the use of machinery; the coal-cutting machine is in general use, the electric power drill employed to a lesser extent. Therefore it may be said that the principal difference in the process employed, mechanical loading versus hand loading, lies in the fact that some type of loading machine is employed in the mechanical loading process to lift the coal from the face of the room, place or entry, after it is mined, placing it in the pit cars for transport to the tipple. It is a common practice to compute accident records on the basis of tons mined per fatal and per nonfatal accident, disregarding the fact that it is possible to produce by the aid of coal-loading machines the same daily, monthly and annual tonnage with a much smaller force than is required where the coal is all shoveled by hand. Inasmuch as the men who are released by the substitution of machinery for hand labor must find employment elsewhere, suffering some measure of hazard in their new occupation, we are of the opinion that the true relative hazard that attaches to the processes of mechanical loading and hand loading can be determined only by using as the basis of comparison "man shifts worked" or "hours of exposure" experienced per accident. The Union Pacific Coal-Co., beginning with the year 1929, undertook to maintain a true record of man shifts worked per compensable accident, giving equal weight to fatal and nonfatal accidents. Accidents lacking sufficient severity to come under the compensable terms of the Workmen's Compensation Act were not included in the compilation, the Act providing that "no compensation, except the expense of medical attention, shall be allowed for the first seven (7) days of disability, unless the incapacity runs beyond the period of twenty-one (21) days, in which case the compensation shall run from the time of the injury." With the further thought that all accidents suffered by employees engaged in any service, in or about the place where the loading process

Jan 1, 1931

By J. H. Nead

The experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. Conclusions No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability. Composition of Materials An attempt was made to secure steels increasing in carbon by increments of 0.1 per cent. from 0.1 per cent. up to 0.8 per cent., and from that composition to 1.6 per cent. by increments of 0.2 per cent. Actually, however, steels of the composition given in Table I were procured, and as the carbon contents were arranged sufficiently well so that satisfactory curves could be drawn showing the relation between carbon content and other properties, these steels were used in the experiments.

Jan 1, 1916

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

Ingots of four steels (1045, 1080, Ni-Mo-V, and Ni-Cr-Mo-V) were cast at pressures varying from about 1 to 760 mm of mercury, so as to obtain a range of hydrogen contents in each steel. The susceptibility of these steels to flaking was evaluated by cooling hot-rolled blooms at a range of cooling rates, varying from water quenching to slag cooling, and studying the occurrence of flaking as a function of cooling rate. The steels exhibited differences in susceptibility to flaking, and a tlzreshold value for hydrogen content for each steel was found, below which the susceptibility was very low and above which the susceptibility increased markedly with increasing hydrogen content. Mechanical property evaluations, metallogvaplzic exantinations, and X-my diffraction determinations o,t retained austenite were made on samples from the blooms. A mechanism of flaking which is consistent with the observed behaviors, the effects of hvdrogen content, and the differences in susceptibility among the steels investigated is postulated, based on the results of mechanical property evaluations and metallographic and X-ray diffraction studies. ThE important role of hydrogen as a factor in the occurrence of "flakes" or "hair-line cracks" in steel has now been established by many investigations. These have included investigations by steel producers and forging manufacturers, to whom the prevention of flaking is a very real and serious problem, and many research studies aimed primarily at establishing the mechanism of this behavior Several investigators3 have reported that steels cast at reduced pressures (absolute pressures of about 1 mm) not only are low in hydrogen content but are essentially insensitive to the formation of flakes. These investigations have shown that a general relationship exists between hydrogen content and susceptibility to flaking. The difficulty of obtaining suitable samples of steels of a given composition with the desired range of hydrogen contents, particularly in the relatively large sections in which flaking most commonly occurs, has been the principal obstacle to quantitative evaluations of these relationships. Steels with intermediate hydrogen contents between 1 ppm, and the 4ppm or higher of air-cast steels are generally not available in commercially produced steels. Laboratory procedures, in which the hydrogen is introduced into solid steel samples by heating in a hydrogen atmosphere under pressure, generally involve a limitation in the size of the sample which can be treated, and thus are not representative of the behaviors in large sections. The availability of a facility at the South Chicago Works of U.S. Steel, in which several ingots could be cast from a single heat of steel at total air pressures ranging from 0.25 to 760 mm of Hg, has made it possible to overcome this obstacle and to obtain ingots of a given steel covering the intermediate range of hydrogen contents desired. These ingots, furthermore, are of a size suitable for the production of product with section sizes large enough to be representative of the products in which flaking most commonly occurs in commercial production. In these experiments, this facility was used to study the relationships between hydrogen content and the susceptibility to flaking of four steels, two plain carbon steels at 0.45 and 0.80 pct C and two low-carbon alloy steels representing a medium and a rather high hardenability level. These flaking studies were supplemented by evaluations of mechanical properties and by metallographic studies on samples from the blooms, in order to obtain pertinent information on the factors other than hydrogen content which influence the susceptibilities of these steels to flaking. Based on the results of these tests, a mechanism for the initiation and propagation of the flaking cracks, which is consistent with the observed behaviors, is postulated. MATERIALS AND EXPERIMENTAL WORK Steelmaking and Conversion. To provide material for the investigation, five 29- by 35-in., hot-topped, big-end-up ingots were cast from each of four 80-ton, basic electric-furnace heats of four different steels (a 1045 steel, a 1080 steel, a Ni-Mo-V steel, and a Ni-Cr-Mo-V steel). A double-slag practice was used on all steels and the two plain carbon steels were Si-A1 deoxidized with an addition of 2 lb of A1 per ton, while the Ni-Mo-V and Ni-Cr-Mo-V steels were deoxidized only with silicon and

Jan 1, 1964

By D. E. Menzie, D. L. Dauben

This paper discusses the physical parameters involved in the slow flow of high molecular weight polymer solutions in porous media. The interacting effects of polymer properties and porous media properties on flow performance are considered. Experiments were conducted with the polyethylene oxides, with molecular weights ranging from 200,000 to over 5,000,000. Frontal advance velocities ranged from I to 30 ft/day. The porous matrix consisted of a flow cell packed with glass beads. Polymer solutions were characterized by viscosity and normal stress measurements. Under certain conditions, unexpectedly high flow resistance was observed. This behavior was observed to be a function of flow rate, pore size, polymer molecular weight and concentration. The polymer solutions exhibit "dilatant" flow behavior in porour media in contrast with the pseudo-plastic behavior in simple flow systems. A theoretical ex-planation of such behavior is presented. INTRODUCTION The use of polymers in the injected water of a waterflood increases oil displacement efficiency by reducing the mobility (k,/pu) of the driving phase. A reduced driving phase mobility results in improvements in the areal sweep efficiency and in the vertical coverage in stratified reservoirs. This mobility reduction may be achieved by a permeability reduction, a viscosity increase or by a combination of the two. Early attempts at increasing the injected water viscosity were not successful because of the poor economics involved. The use of such materials as glycerin, sugar or glycols to increase water viscosity was not economically feasible. Attempts in using certain naturally occurring polymers were not too successful because of the high polymer losses to the rock. A high molecular weight, partially hydrolyzed polyacry-lamide was introduced 3 years ago as a waterflood additive.',' Initial work by Pye' indicated that the presence of these polymers in dilute concentrations decreases the water mobility 5 to 20 times more than would be expected from measurements of the solution viscosity. Such an effect would be of obvious economic value since only a small polymer concentration would be required to accomplish a large reduction in water mobility. This research was designed to study the basic flow mech anisms of polymer solutions in porous media. The interacting effects of polymer properties and porous media properties on flow performance are considered. This study indicates some of the conditions under which these interactions can lead to significant mobility effects. is valid only for Newtonian fluids. For polymer solutions and other non-Newtonian fluids the equation must be modified to consider that viscosity is a variable quantity. Modification of the Darcy equation to include non-Newtonian effects has been the subject of several recent investigations."" The modifications generally adopt a rheological model. such as an Ellis or Dower law model. to Dorous media by defining some characteristic channel radius. Most of these studies showed the porous media flow behavior to be predictable from viscometric data. Investigations involving the flow of high molecular weight polyacrylamide solutions through cores have generally encountered the high flow resistances reported previously by Pye. This high flow resistance has generally been attributed to an in-depth permeability reduction, as evidenced by a reduced permeability to water which has displaced polymer solution from the porous media. Marshall and Metzner" report high flow resistances, which they attribute to viscoelastic effects. In this paper, the effects of polymer molecular weight, pore size, flow rate and concentration are considered. The polymers used are the polyethylene oxides known as Poly-ox. This class of polymers was used because of its availability in a wide range of molecular weights and because of its known ability to propagate well through porous media. THEORY PHYSICAL PROPERTIES OF POLYMER SOLUTIONS The polymer molecule dissolves in water by means of hydrogen bonding, but retains some of its own structural identity while in solution. Nonionic polymers, such as polyethylene oxide, are generally considered to have a random coiling configration. This type of molecule has the ability to "sequester" or hold a large volume of solvent within its coils in a manner similar to that of a sponge. The random coil is easily deformed and under an applied stress

Further discussion of the paper of JAMES JOHNSTON, presented at the New York meeting, February,. 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133. See also Bulletin No. 91, July, 1914, pp. 1473 to 1496. THOMAS CROWE,* Victor, Colo.-The interest manifested of late in the treatment of low-grade ores, together with Mr. Clevenger's discussion of the Mill and Metallurgical Practice of the Nipissing Mining Co., prompts me to acid a few remarks relative to concentration in connection with cyanide treatment of low-grade ores. Mr. Clevenger in this discussion does not condemn concentration in this connection, but, nevertheless, the tone of his remarks would lead one to believe that his conclusions are like those of many others: that concentration is often turned to as a last resort in an attempt to improve or obtain an extraction upon an ore by the recovery and sale of the refractory portion of the ore. This, I will attempt to point out, is not always the case. Concentration in connection with cyanidation often performs an entirely different function, i.e., one of saving fine grinding. Economy being the keynote of successful treatment of low-grade ores, the problem often becomes more commercial than metallurgical, and, as there is generally a definite ratio existing between cost of operation, degree of comminution, and percentage of extraction, the grade of ore under treatment usually imposes a limit upon these factors. With many ores grinding is the most expensive single item in their treatment; therefore, the degree of comminution is very apt to be governed by the allowable cost of operation. With most ores the degree of comminution controls to a great extent the percentage of extraction. So in the treatment of low-grade ore it often becomes necessary to sacrifice extraction, through coarse grinding for the benefit of cost, in order that the greatest ultimate profit may be obtained, and it is under these conditions that it is, possible for concentration to play an important part in overcoming to some extent the effect of mesh. The precious metals occurring in an ore are usually closely associated with the metallic portion of the ore, and as this metallic portion is generally fairly well liberated from the gangue at comparatively coarse meshes, further grinding of the ore is necessary only in order that the metallic portion may be reduced sufficiently fine that the precious metal part of it may be dissolved by cyanide solutions in a reasonable length of time.

Jan 11, 1914

By R. A. Fitch, J. D. Griffith

A performance calculation method was used in conjunction with experimental studies to develop means of predicting and interpreting miscible floods and to explore possible methods. of improving their efficiency. The calculation method is based upon the division of reservoirs into multiple independent zones or strata. Comparison was made with some experimental floods and with a field project to obtain some measure of the applicability of the method. Two aspects of miscible flooding were considered: (I) the displacement of a miscible front through a reservoir, and (2) the distribution and utilization of the solvent volume injected to maintain miscibility. Calculations and experihental observations indicate that alternate gas-water injection behind a miscible front significantly improves miscible flood performance, both within a single stratum and in a multistrata reservoir. Calculations were made on the extent to which miscibiliry is maintained by a given solvent volume in a stratified reservoir. Two alternate criteria for determining the optimum volume of solvent for injection are discussed. The preinjection of a small volume of water ahead of the solvent is suggested as a method of obtaining more efficient utilization of solvent. Calculations and experiments were made to investigate the effects of water preinjection. INTRODUCTION Miscible fluid displacement as a possible means of recovering oil has been the subject of extensive research and numerous field tests over the past several years. This work has brought out both favorable and unfavorable features of the miscible recovery methods. Many tests have shown that a miscible fluid can displace all of the oil contacted, leaving no high residual oil saturation, as is characteristic of immiscible displacements. The miscible methods have proven dificult to control, however, as evidenced by early breakthrough of the displacing fluid and poor sweep efficiency in several field projects. It became apparent early in the investigation of miscible displacement that the development of improved techniques and better methods of control would be required to extend the range of applicability to any significant portion of our petroleum reservoirs. The purpose of this study was to consider the problem of designing miscible floods to obtain better performance. A performance calculation was used in conjunction with experimental studies to develop means of predicting and interpreting miscible floods and to explore possible methods of improving their efficiency. Two aspects of miscible floods were considered separately in this study and the results are presented in two parts. The first part concerns the manner in which the miscible front is displaced through the reservoir. In these calculations the condition of miscibility between the reservoir oil and the displacing fluid is assumed. In the second portion the distribution and utilization of the preinjected solvent in maintaining rniscibility is considered. This portion dealing with solvent utilization applies only to the enriched gas or LPG slug processes. CALCULATION METHOD AND EXPERIMENTAL STUDIES COMPUTATIONAL MODEL The calculations for expected reservoir performance are based upon the multi-strata concept of reservoir properties. The method assumes multiple, independent strata (no crossflow between strata) and explicitly includes variations in patterns, injectivity, areal sweep and displacement efficiency. Lateral variation in permeability within the strata (for example, directional permeability) may be considered in the calculations, provided the variations are similar in all strata. The calculations based on this model furnish the rates of injection and rates of production of both oil and the displacing fluid for the composite system of strata. To carry out calculations on the mathematical model described, information is required on the performance of the displacement process under consideration in a single stratum element of the pattern to be used. In particular, for a given pattern and displacement process, data are required relating injectivity and composition of the produced stream to the volume of fluid injected. Data on the variations in areal sweep must also be available if it is desired to track the areal sweeps in the multi-strata model. These data may be obtained from experimental work such as model studies or other suitable methods. This representation of reservoir properties is, of course, an approximation and may be inappropriate in some cases. But the representation is not an arbitrary one since most oil reservoirs are essentially successive layers of sediment with the net producing pay zone often comprising but a fraction of the gross formation thickness. The fact that permeabilities measured in the vertical direction are frequently but a fraction of the horizontal permeability adds some evidence to the validity of this model. This type cal-

Jan 1, 1965

By Elmer A. Jones

Development work in mines of St. Joseph Lead Co., Southeast Missouri, using trackless loading equipment shows definite advantages: Speed of cleaning, ability to work on steep grades and sharp crosscuts, good later tracking conditions, and possibility of wasting rock in old abandoned stopes.

Jan 6, 1950

By Charles F. Brush

THE compression of gases to a very high degree, for purposes of scientific research, has long presented serious difficulties to the physicist. Great advances have been made of late years in the construction of ordinary air or exhaust pumps, while very little has been done towards the improvement of compression pumps. The principal difficulties encountered in the construction of such apparatus are the existence of the so-called "dead space" in the pump barrels, leakage of the piston packings under high pressure, and the trouble arising from the unequal expansion of parts caused by the development of the latent heat of the gas during compression. Of these obstacles to success, the "dead space" is far the most serious, as it fixes a limit to the performance of the pump beyond which it is impossible to carry the compression. The writer having occasion, some time since, to make a series of investigations on gases very highly compressed, and finding no apparatus, or description of apparatus, adequate to produce the required

Jan 1, 1876

By Charles F. Brush

The compression of gases to a very high degree, for purposes of scientific research, has long presented serious difficulties to the physicist. Great advances have been made of late years in the construction of ordinary air or exhaust pumps, while very little has been done towards the improvement of compression pumps. The principal difficulties encountered in the construction of such apparatus are the existence of the so-called "dead space" in the pump barrels, leakage of the piston packings under high pressure, and the trouble arising from the unequal expansion of parts caused by the development of the latent heat of the gas during compression. Of these obstacles to success, the "dead space" is far the most serious, as it fixes a limit to the performance of the pump beyond which it is impossible to carry the compression. The writer having occasion, some time since, to make a series of investigations on gases very highly compressed, and finding no apparatus, or description of apparatus, adequate to produce the required

By P. A. Beck, Hsun Hu

It has been known for many years that in cold drawn polycrystalline aluminum the recrystallization texture is practically identical with the deformation texture.l,2,3 V. Goeler and Sachs4 stated that in cold rolled polycrystalline aluminum, too, the deformation texture is retained upon recrystallization. This behavior was interpreted by Dehlinger9 as an indication that each recrystallized grain inherits the orientation of the matrix in which it grew. However, Burgers and Basart showed6 that in deformed aluminum single crystals the orientation of the recrystallized grains strongly deviates from that of the matrix. Barrett demonstrated8 that even in deformed polycrystalline aggregates the local orientation within each deformed grain changes on recrystallization. No explanation has as yet been offered of how the aggregate texture can be retained, while the local texture is everywhere changing. According to Burgers and Louwerse6 the orientation change on recrystallization in compressed and rolled aluminum single crystals corresponds to a rotation around [112] axes lying in the active slip planes and perpendicular to active slip directions. This orientation change was rationalized by them on the assumption that the orientation of the recrystallized grains is determined by the orientation of the available nuclei, and that these nuclei are small fragments of the deformed crystal, rotated in the deformation process. Barrett pointed out,? however, that these assumptions were by no means proven, and that the total volume of material necessary for the nuclei is so small, that it must be available in any orien- tation whatever. It is, therefore, unlikely that an "oriented nucleation" theory could satisfactorily explain the orientation changes in recrystallization of a deformed crystal. Furthermore, in contradiction to Burgers and LOU-werse's conclusions, Barrett's results for the orientation change could be best expressed in terms of rotations around. [Ill] axes. Thus agreement is lacking not only in the interpretations but apparently even in the experimental results contributed by the various investigators. The orientation relationships on coarsening* in a highly oriented polycrystalline matrix were first investigated by Burgers and Basart.5 They produced a fine grained highly oriented matrix by the recrystallization of a compressed or rolled single crystal of aluminum, and studied the orientation relationships in three successive generations of crystals: the "deformation texture" in the single crystal, the recrystallization texture, and the coarsening texture. Burgers24 showed that the preferred orientation of each successive generation was almost always widely different from that of the preceding one, but that the coarse grains often approximately reverted to the orientation of their grandparent, the deformed single crystal. This observation, and the idea that the orientation of the coarse grains is determined by that of the available "nuclei," led to the concept that the coarse grains are nucleated by the remnants of the deformation texture.12,15 On the other hand, Bowles and Boas16 found, in a carefully conducted experiment, that in recrystallized fine grained copper of cube texture coarse grains grow in orientations which can be derived from the orientation of the recrystallized matrix by rotation around a [lll].] direction: the coarsening texture here does not appear to be related in any simple manner to the original rolling texture from which the cube texture had been obtained by recrystallization. It may be assumed that in a recrystallized material, even with a strong texture, there always are present some grains of practically any orientation. These may serve as "nuclei" for the coarse grains, provided that the conditions are favorable for their growth. The existence of a coarsening texture may be considered as an indication that grains with certain relative orientations with respect to the preferred orientation of their neighbors can grow much faster than others. This "oriented growth" theory was briefly suggested by van Arkel, as early as 1936,13 and it was mentioned by Burgers." Recently, C. G. Dunn produced direct

Jan 1, 1950

By W. L. Saunders

It is now generally admitted by experts that at least so far as rapid progress is concerned the Alpine system of tunnel-driving is superior to any other. This is perhaps natural in view of the record of experience in driving tunnels through the Alps. These great mountain-chains cannot be treated in the ordinary way by shaft-sinking and driving headings, thus multiplying the points of attack. The work must be done from the ends only, hence speed in driving is of the utmost importance ; and, as necessity is the mother of invention, the concentration of effort to make progress has resulted in an organization and in mechanical appliances that have produced results so much in excess of the usual practice, even in America, that a discussion of the subject in detail should be of much value to the engineer and contractor. The first Alpine tunnel mas the Mont Cenis, length 7.5 miles, driven with a progress that averaged about 7.75 ft. per day. Next came the Saint Gothard, 9.5 niiles long, 18 ft. per day; Arlberg, 6.5 miles long, 27.25 ft. per day; Simplon, 12.25 miles long, 36 ft. per day. The figures represent progress when driving from two headings, so that by dividing them in two we get the daily single-heading progress. The latest of the Alpine tunnels is the Loetschberg, now being driven. In this work the world's record has been beaten by a single day's record in one heading of 36 ft. and by an average daily record in one heading of 29.5 feet. The Alpine range forms a natural barrier between a large section of northern and southern Europe. This range extends from the southeast of Prance to the frontier of Hungary, betveen Italy and the plains of sonthern Germany. The contour

Jan 1, 1912

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

By C. S. Allen

With increased coal production and mechanization of coal mines many transportation problems arise. The main objective is to bring the coal to the tipple or dump it as quickly as possible. Larger and faster haulage locomotives or two locomotives connected in tandem have been adopted to solve the problem. Motor equipment, gears and control systems of locomotives to be placed on these hauls are carefully studied to meet these requirements, by an analysis of motor characteristic curves with the corresponding tractive effort curves, in order to determine the correct load for maximum efficiency and to determine the approximate schedule. Control equipment is usually considered to be the controller and resistance. Sometimes accelerating curves are calculated in order to obtain smooth starting in the least possible time without slipping the wheels. Train control is very important, but why limit this to acceleration ? Deceleratien-or-retardation of the locomotive is a part of the train control and should be given as much consideration as the control for acceleration. Types or Braking Common braking systems for mine locomotives utilize screw-type mechanical brakes, dynamic braking and the air brake. For gathering and haulage locomotives, the srrew-type mechanical brake is regarded as standard. A brake of this kind cannot be applied without much effort and lapse of time. Motormen, like other people, follow the path of least resistance, and therefore have their brakes ready for instant application—which means that the shoes are virtually dragging. Even then, a motorman bucks and plugs the motors to gain time and avoid as much physical effort as possible. "Bucking of motors" consists in turning the reverse cylinder of the controller to parallel position corresponding to the opposite direction of travel while the locomotive is in motion, without applying power from an external source. When this occurs, both motors tend to act as series generators, because the armatures are revolving and there is residual magnetism in the field circuit. Owing to slight differences in motor manufacture, one of these will generate a slightly higher potential and will overcome the generated voltage of the second and tend to drive it as a motor in the reverse Direction.-This action retards the locomotive but is very severe on the segments of the reverse cylinder and on the motor commutators. "Plugging motors" is the application of power to the motors corresponding to the opposite direction of travel. In order to "plug" the motors it is necessary first to "buck,, them (which reverses the connections to the motors) and then to apply power. Theoretically, this should be done only in an emergency, but locomotives in mine service are frequently thus treated., Dynamic braking is retardation of the locomotive by the motors acting as generators, which take no power from the line.

Jan 1, 1942

THE preceding chapter has recorded the initiation of mineral industry education during the period 1890-1910 in numerous institutions that had not previously offered it. It should also be emphasized that in many institutions where instruction had begun before 1890, as recorded in earlier chapters, but had not yet become firmly established, this period was one of marked growth and development. This was not universally true, however, for at the Universities of Pennsylvania, Michigan, Illinois, Wisconsin, Washington (St. Louis), Iowa, Vanderbilt and Tennessee, and at the Polytechnic College of Pennsylvania, mineral industry instruction was being dropped during this period, instead of gaining in strength. It is necessary to emphasize this, because writers on the subject have not infrequently attempted to make a much too simple correlation between mineral discovery or production and the intensity of student interest in mineral industry curricula. It would naturally be true that periods of large mineral production would, in general, coincide with cycles of business prosperity, and the latter are conducive to starting new ventures, educational as well as business. It should be equally evident that opportunities for business and professional success might, in such periods, appear to increase at a more rapid rate in industries other than mineral, or in the utilization of minerals rather than in their production. The author has not been able to perceive any simple and clear relation between interest in mineral industry education and mineral discovery, production, and utilization, or general business prosperity. On the contrary, the more the problem is studied the more complex the factors involved in it appear to be. In a later chapter an attempt will be made to analyze them in more detail

Jan 1, 1941

By C. S. Barrett, D. B. Masson

Martensitic transformations have been found in AgCd both upon cold-working at room temperature and cooling to lower temperatures. The crystal structures of the transformation products were found to be close-packed hexagonal in the first case and or-thorhombic in the latter. The transformation characteristics also were studied. Similar treatment of AuZn alloys failed to yield any transformation. THE literature on martensitic transformations of body-centered cubic metals and alloys indicates widespread instability of this structure at low temperatures, a tendency which merits further study. The body-centered cubic ß-phase of CuZn, for example, when it contained less than 42 wt pct Zn, was found by Greninger and Mooradian' and others' to transform on cooling to subzero temperatures to a phase that was tentatively considered to be tetragonal. Further work by Massalski and Barrett" demonstrated that cold work at low temperatures causes a partial transformation of ß CuZn of higher Zn content. The structures of the strain-induced transformation products were found to be different from those induced by simple cooling. Another well-known martensitic transformation among body-centered cubic phases is that of ß AuCd, first studied with X-rays by Olander,' then very thoroughly by Chang and Read.5,6 Here again transformation was found to occur both as a result of cooling and of strain. The alkali metals Li and Na, as well as certain Li-Mg alloys, also undergo transformation from their normal body-centered cubic structure, both on cooling and on cold-working. The phase AgCd, the subject of the present report, should be expected to behave quite similarly to CuZn for a number of reasons. It is the chemical analogue of CuZn, silver being directly below copper and cadmium directly below zinc in the periodic table. The size factors (percent difference in size) of the atoms, possibly a consideration in the stability of the ß-phases, are +3.1 in AgCd and + 4.2 in CuZn. Likewise the relative electronegativities of the two pairs of metals are about the same, CuZn possessing an electronegativity difference of 1.0 and AgCd one of 0.8. These values are from a table of electronegativities given by Darken and Gurry." The phase diagrams of the two systems around 50 atomic percent are similar, both possessing a disordered body-centered cubic phase, ß, at high temperatures and an ordered bcc phase, ß, at room temperature; however, the ß and ß' phases of AgCd are separated by a hexagonal phase, [, stable in the range 220-440oC, which has no analogue in CuZn. There has been confusion in the literature as to the structures of the ß' and [-phases. The phase diagram in the ASM handbook'" has the structures of the two phases interchanged; however, Hansen" reports the correct relative positions and Muldawer" verified that ß', the low-temperature phase, is body-centered cubic. Work by the present authors also

Jan 1, 1959

By R. D. Pehlke, J. V. Gluck

A study was made of the effect of small additions of metallic solutes on the thermodynamic activity of zinc in dilute solution with molten bismuth in the range 450o to 650°C. The experimental measurements were made in a multielectrode galvanic cell using. a fused LiCl-KCl electrolyte. The activity of zinc in binary solution exhibited a strong positive deviation from Raoult's law and obeyed Henry 's law to at least 0.050 mole fraction. The ternary addition of lead, gallium, or indium increased the activity of zinc. Cadmium or tin additions slightly decreased the zinc activity. Copper, mercury, silver, or antimony caused moderate decreases, while gold strongly decreased the zinc activity. The results are expressed in terms of Wagner's interaction parameter ejZn and a second-order cross-interaction parameter. The interactions for copper, gold, silver, and antimony showed a linear dependence with reciprocal absolute temperature, while the other interactions were essentially independent of temperature over the experimental range. Since tin and antimony decreased the zinc activity, the hypothesis of a purely periodic variation with atomic number was rejected. A semiquantitative explanation was possible with a free-electron model when relative electronegativities were used to express changes in the electron/atom ratio caused by the solute addition. Random solution and quasi-chemical models correctly predicted the majority of the interactions for which binary data were available to apply them. A knowledge of the thermodynamic interactions in liquid (and solid) metallic solutions is of considerable theoretical and experimental interest in the formulation of quantitative thermodynamic relations for metallurgical processes. The approaches to defining the interactions may be either phenomenological (i.e., "What mathematical function adequately describes observed behavior and permits extrapolation to new situations?") or theoretical, such as a specific model

Jan 1, 1968