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By E. A. Gulbransen, W. S. Wysong, K. Andrew

INTRODUCTION THE reaction of carbon in solid solution in a metal with the surface oxide film on many metals may be inferred from thermodynamic calculations for high vacua and high temperature conditions. Holm1 has recently shown that oxide films may be removed from ferrous materials by heating in a vacuum at high temperatures and that carbon is the essential element in the reaction. Considerable work has been described in the literature on the decarburization reaction. Several general references may be noted.2,3,4 However, the nature of the mechanism involved in the decarburization is not well understood. Our interest in this reaction resulted from many attempts to degas and to reduce by pure and dry hydrogen the surface oxides 0n strips of various types of chrome-nickel alloys. Some of the early experiments on the behavior of 13 pct chrome-iron in vacua of the order of 5 X 106 mm and at a temperature of 600°C have been reported.5 These experiments showed a slow reaction with the residual oxygen or water vapor in the system and no reaction with hydrogen. This is in accord with thermodynamic data which would lead to the prediction that it is extremely difficult to maintain a hydrogen atmosphere at 600°C pure enough to reduce Cr203 formed on the surface. The crystal structure of the superficial oxide film formed on 13 pct chrome iron and Nichrome V has been investigated in the thin film range by Gulbransen, Phelps and Hickman,6 and shown to be Cr203. It was surprising to us to note that when a specimen of Nichrome V containing approximately 80 pct nickel and 20 pct chromium was heated to 850°C in a high vacuum, the specimen' lost weight. The rate of weight loss was very temperature sensitive. A study of this reaction in vacua and in a hydrogen atmosphere is the subject of this communication. TYPE REACTIONS Let us consider the various reactions which may occur when a metal is heated in vacua, in a hydrogen atmosphere, or in an oxygen atmosphere. The number and kind of reactions will depend upon the chemical nature, of the metal, its alloying constituents and the location of the alloying constituents. The metals used in this study are chrome-nickel alloys of the heater type. They consist essentially of chromium, nickel and iron, small amounts of carbon, silicon and manganese and traces of zirconium, calcium, aluminum and magnesium. The trace elements are added to improve the lifetime and other characteristics of the alloy when used as a heater. Seven of the more important reactions with which we are going to be concerned here are as follows: [I. Metal • (gas) ;--* metal + gas - degassing of the metal 2. xM(s) + y ½ 02(g) tom- M.0„ (s) – oxidation]

Jan 1, 1948

By E. C. Babson

In order to explore the possibility of predicting reservoir performance from laboratory data, behavior of a hypothetical low-permeability reservoir has been estimated by applying data and methods currently available in the literature. A method of calculating decline in productivity index is discussed, and recoveries by internal gas drive, external gas drive and water drive are estimated. Introduction During the life of a producing oil property an operator is faced with many perplexing problems. Any attempt to determine proper well spacing, optimum rate of production, or the desirability of pressure maintenance requires the evaluation not only of a host of economic and practical operating factors but also of the future performance of the reservoir. Although in some cases economic or operating con-siderations may be of primary importance in planning a development or production program, the anticipated effect on ultimate recovery is more likely to be the decisive factor. The soundest basis for evaluating reservoir performance is past experience with oil fields, but pertinent data are difficult to obtain or apply under conditions normally encountered in California fields. Many of these fields are characterized by thick sections of alternating sands and shales complicated by faulting and rapidly changing lithologic conditions. Further compli- cations are introduced by haphazard development and production practices resulting from competitive conditions, changing demand for oil, and insufficient knowledge of structural conditions during early development. Even in the rare cases where development has been systematic and adequate, production policy has usually been controlled by economic and competitive factors rather than a desire to obtain information for use in future operations. In other words, comparable reservoirs in which development and production practices have been systematically varied are seldom found. In the light of these conditions, conclusions based on experiences usually lack the certainty required for decisions involving large sums of money. Some other method of attacking these problems is needed to supplement and orient field experience. Progress in laboratory investigations of the flow of oil, gas, and water through sands has been so rapid in recent years that these data may furnish such a supplementary approach in the near future. In order to explore this possibility the author has attempted to predict the behavior of one type of reservoir by applying published data and methods. Basic Data and Assumptions Calculations outlined in this paper are dependent upon a detailed knowledge of the properties of oil, gas, and water present in the reservoir and the portion of the total pore space originally filled by each. It is also necessary to know how the permeability of the sand to oil, gas, and water varies with the saturations of these fluids 20

Jan 1, 1944

By J. B. Bassett, E. S. Rowland

The experimental work reported herein firas inspired by the publication of a paper by Grange and stewart, in which it was suggested that at low chromium contents the effect of this element on the Ma point was greater than at higher chromium contents, It was argued that, if a small increase of chromium in solution in austenite caused a sharp lowering of the M, point, it might lead to an explanation of occasional unsolved stress cracking of SAE 52100 during heat treatment. Commercial hardening is carried out at temperatures of incomplete solution, leaving carbides available to enrich the austenite during any inadvertent increase in temperature, such enrichment of the austenite in chromium content would lower the M, point nearer room temperature where cracking is more likely to occur. According, it was decided to investigate the effect of chromium, in quantities between o and 2 pet, on the M, point of commercial steels. Fig I summarizes the data available on chromium steels. For purposes of comparison, the M, temperature values were corrected by means of the Grange and Stewart formulas to (I) Hypoeutectoid compositions: 0.50 pct carbon and 0.80 pct manganese (z) Hsereutectoid compos-sition': 1." pet carbon and O.35 pct manganese. Only the steels having compositions reasonably close to these corrected values were included, because large adjustments inevitably introduce increased error such as are experienced in using the formula. The straight lines of Fig I were drawn by the authors. These data obviously do not settle the question Of the effect Of chromium On the Md Oint, particularly at low chromium contents. While it is fairly well established that chromium causes the M, to be lowered when present in quantities of I pet Or more, Grange and Stewart1 have suggested that in small amounts (less than 1 pet) it is more effective in lowering the Ma point, while Klier and Troiano2 have suggested that in small amounts it is less effective in lowering the Ma point. Payson and Savage3 concur with Klier and Troiano and further suggest that the effect is not linear at these concentrations. Rose and Fischer4 report that small amounts of chromium actually raise the Ma point of a 0.20 carbon steel. Material Two series of 35 Ib induction heats were melted for this work, the analyses of which are given in Table I. One series was aimed at 0.50 pct carbon and 0.80 pct manganese with chromium additions in 0,25 pet increments from o to 1.5 pct with a single heat at 2.0 pct Cr. This series was considered necessary because the commercial heat treatment of SAE 52100 does not generally introduce more than about 0.60 pct carbon in solution in the austenite. The high

Jan 1, 1949

By Lloyd R. Jackson

In the past 15 years there has been a great deal of interest in the fundamentals of plastic flow and rupture in metals and a number of papers have presented substantial advances toward a fundamental insight into the mechanism of these two processes. This paper is an appraisal of the present position with respect to the following: 1. The relative importance of shear and hydrostatic stresses in controlling the plastic flow of metals. 2. The relative importance of shear and hydrostatic stresses in determining the amount of flow before rupture in metals. 3. The use of generalized strains in determining the effect of plastic flow on the work-hardening of metals. FundamentalS Involved in Plastic Flow In attempting to devise a quantitative description of plastic flow in metals, it has been customary to assume that metals are homogeneous and isotropic. The fact that neither of these assumptions is correct complicates the experimental appraisal of relations developed. Nevertheless, as will be shown, metals are close enough '0 being isotropic and homogeneous so that considerable insight into the mechanism of plastic flow can be obtained. The assumptions of isotropy and homogeneity allow both the elastic and plastic behavior of metals to be described in terms of 12 variables—six being stress variables, and six being strain variables. From this viewpoint, it should be possible to represent the stress-strain relations in the plastic range for metals by a surface in 12 dimensions. One boundary of this surface would be the surface of transition from elastic to plastic behavior; the other would be the surface of rupture. These two surfaces would be joined by the surface of plastic flow. The shape of this composite surface would depend on the test temperature and speed of straining This paper is concerned only with results obtained at constant temperature and constant speed of straining. While such a representation is conceivable, the demonstration of such a surface would present almost insurmountable obstacles. The most fruitful simplification of this concept has been the recognition that the behavior of metals in the plastic region is primarily a result of shear stresses and strains. Based on this viewpoint, it is possible to utilize stress and strain invariants that are independent of hydrostatic components to define an effective stress and strain. In effect, this amounts to reducing the task of representing stresses and strains in 12 dimensions to one of representation in two dimensions. The two invariants (one for stresses and one for strains) that have received most attention are the following: q2 = ½[(Txx= - Tyy)2 + (Tyy - Tzz)2 + (Tzz - Txx)2 + 3(Txy2 + Tyz2 + 7xx2) [1]

Jan 1, 1947

By M. J. Marcinkowski, D. Koskimaki, A. S. Sastri

THIS is the second in a trilogy of investigations carried out in order to understand the solid state transformations and their accompanying effects on the deformation behavior of near-equiatomic Ni-Ti alloys. The first stage of this effort has dealt with the strictly martensitic structures obtainable in these alloys, i.e., those in which diffusion processes were not involved.1,2 These martensites could be produced either by rapid quenching or by plastic deformation of the originally B2 type phase. The present investigation, on the other hand, will deal with those transformations in Ni-Ti which do involve diffusion. A majority of investigators3-10 have shown that the B2 modification of TiNi, which is stable at elevated temperatures, decomposes into one or both of the intermetallic compounds NiTi2 and Ni3Ti below about 650°C. On the other hand, this has been disputed by several Workers was undertaken in order to resolve this discrepancy, as well as to shed more light on the nonmar-tensitic decomposition of B2 NiTi. EXPERIMENTAL PROCEDURE Sample preparation, fabrication, and examination were the same as those described previously in Ref. 2. In addition to the 50 at. pct Ni (55.06 wt pct) hypoeu-tectoid alloy used previously, a second hypereutectoid alloy containing 54.4 at. pct Ni (60 wt pct) was also prepared for this study. RESULTS AND DISCUSSION The equilibrium diagram for the Ni-Ti alloy system in the vicinity of Ni-Ti is shown in Fig. 1. The solid lines have been established by the work of Poole and ~ume-Ftothery4 whereas the dotted lines are based on findings obtained in the present investigation as described below. Structure and Morphology. Fig. 2(a) shows a bright field transmission electron micrograph of a two-phase structure obtained in a polycrystalline Ni-Ti alloy that was furnace cooled (approx 200°C per hr) from 1050' to about 300°C. Large plate-shaped precipitates can be observed in a matrix which was found by electron diffraction to possess the high temperature B2 structure. A selected area diffraction pattern of the region covered by Fig. 2(a) is shown in Fig. 2(b), while Fig. 2(c) is a detailed schematic interpretation of Fig. 2(b). The B2 matrix reflections are illustrated by squares while those of the precipitate are shown as circles. The d values associated with the precipitate reflections could be determined quite accurately since the reflections from the B2 matrix, for which the lattice constant is known precisely, were simultaneously present in the diffraction patterns. All of the reflections

Jan 1, 1970

By Thomas D. Bailey, Alec M. Crowell

Although natural gas was first discovered in Northwest Arkansas in 1887, . near Fort Smith, Sebastian County, the literature contains very little information on the region, which is separated distinctly from the oil area of Southern Arkansas. For that reason this brief and concise report is a summary of developments from discovery to the present time. Northwest Arkansas produced 5,736,-ooo,ooo cu. ft. of natural gas during 1942, the trend of production having been generally upward over the past five years, as is shown in Fig. I. Since 1904 a reserve of 237 billion cubic feet of natural gas has been discovered in Northwest Arkansas, of which approximately 162 billion cubic feet have been expended, leaving a reserve of approximately 75 billion cubic feet available as of Jan. 1, 1943. A prolific new field discovered in Pope County Oct. 23, 1942, will add to the reserve of the region materially. Per well reserves, over-all, are unusually high because of the practice of multiple completion. As yet no commercial deposits of oil have been discovered in Northwest Arkansas. but the gas deposits have proved of immense value industrially, principally in the processing of zinc ore mined in the local area as well as that imported from distant states. With the war, new interest in the exploitation of the metallic ores of the region lends new significance to the gas reserves tabulated herein. Geological Discussion The region covered in this report comprises the Arkansas Valley from Pope County weslward to the Arkansas-Oklahoma state line as shown in Fig. 2. This valley is a westward trending structural trough with sharp-topped ridges and mesa-like mountains rising above the valley's undulating surface. It is bounded on the north by the Ozark Highlands and on the south by the Ouachita Mountains. The sedimentary beds of the Arkansas Valley are composed mainly of noniossil-iferous shales and sandstones. The rocks contain a high content of carbonaceous material and many coal beds are found in the region. The Gxed carbon ratios (ratio of fixed carbon to volatile combustible matter of surface coals) are very high and average about 80 per cent over the region covered in this report. Little or no calcareous material is present. Rocks of the Arkansas Valley are sharply folded, and igneous intrusive rocks cut the sedimentary beds at a few places. The Arkansas Geological Survey' made a detailed reconnaissance survey of the Arkansas Valley province in 1927, the purpose being to delineate the major structural features (Fig. 3) and to point out the possibilities of discovering addi. tional gas deposits. More than fifty anticlines were mapped as a result of this survey. The information gained by this

Jan 1, 1943

By K. K. Rao, M. E. Nicholson

IN a recent paper on the solubility of carbon in Ni-Cu alloys,' Nicholson reported that the carbon solubility appeared to be limited by the electronic structure of the alloys and that the solubility was propor- tional to the density of states at the Fermi surface of the "3d" band. In order to determine whether or not this relationship is a general one, the study has been extended to other systems. One of these is the CO-Ni system. This system was chosen for study because 1) it is adjacent to Ni-Cu system in the periodic table, 2) the alloys of cobalt and nickel do not form stable carbides at 1000°C, and 3) the system exhibits no pronounced change (less than 1 pct) in lattice parameter from cobalt to nickel,' see Fig. 1. The alloys were prepared from -200-mesh 99.92 pct Ni furnished by the International Nickel Co. and spectroscopically pure -200-mesh cobalt sponge obtained from Johns on-Matthey and Co. The powders were weighed, mixed, and pressed using a pressure of 40,000 psi. The samples were sintered for 24 hr at 900° C in dry hydrogen and then cold rolled to a thickness of 0.010 in. (Samples containing more than 70 wt pct Co had to be annealed after cold reductions of about 20 pct to avoid cracking.) The alloys were carburized at 1000°C in an alun-durn boat containing Acheson AUC powdered graphite in an atmosphere of carbon monoxide cylinder gas which had been passed through Ascarite to remove carbon dioxide. After carburizing for either 12 or 24 hr the samples were moved to a cool zone of the furnace to cool. Cooling required about 5 min. The samples were filed to remove about 0.005 in. from the surface and then analyzed using a conventional combustion-gravimetric analytic method. The results of this investigation are shown in the lower portion of Fig. 1 and Tabulated in Table I. The nickel percentages for these alloys were determined from the weights of the powders from which the alloys were made. The solubility of carbon in pure cobalt at 1000°C (fcc) is 0.25 wt pct. This is somewhat less than the 0.33 wt pct measured by Boecker.3 From his data, it would appear Boecker's samples were supersaturated before the equilibrating treatment and that a 20-min treatment was not long enough to achieve equilibrium. Since in the present investigation the 12 and 24 treatments produced essentially equal carbon contents, our figure is presumed to represent more nearly the equilibrium value. The solubility of carbon in nickel of 0.19 wt pct agrees quite well with the value of 0.21 wt pct

Jan 1, 1963

By J. O. Mack, J. B. Russell

In recent years, solders containing 20 per cent tin with no bismuth or cadmium have been developed by a few companies, and personnel have been properly instructed in their use. In addition, since the tin shortage, a number of solders containing less than 10 per cent Sn, and some with no tin, are being used in special applications; however, a solder of this type has yet to be developed that is satisfactory for general use. Table i.—Composition Ranges Prescribed for a Commercial Substitute Solder Element Per Cent Tin............................ 18.0-20.0 Bismuth (maximum)a............ 0. 80 Silver.......................... O. 10-1. 25 Bismuth plus silver (minimum).... 0. 85 Antimony (maximum)............ o. 50 copper (maximum),,,,,,,,..,,,, 0. I3 Other elements, each (maximum)6 0.03 Lead........................... balance a When silver is present in excess of I per cent, the Bi content shall be 0.50 per cent or over. b Total not to exceed 0.10 per cent. The Purpose of this investigation was to develop an alloy containing a maximum of 15 per cent tin, with no cadmium or bismuth, having solder properties equivalent to or better than those of substitute solders now specified containing 18 to 20 per cent tin (Table I), or even approaching the properties of the standard 40 to 60 tin-lead solder. The wartime restriction of bismuth and cadmium, elements that have beneficial effects on fluidity, solidification range and strength, makes it increasingly difficult to develop a general-purpose solder containing a maximum of 15 per cent tin. In the course of this investigation, 11 elements were used in various combinations with the basic I5-85 tin-lead alloy. These elements were antimony, silver, copper, indium, thallium, lithium, calcium, barium, potassium, sodium and arsenic. In all, 116 low-tin solders were investigated, with the idea of developing a solder that will give satisfactory working properties, specifically in regard to "wetting" of copper, brass and iron, solidification range, capillarity and shear strength of a soldered joint. The relative importance of these various properties plays an important role in the search for substitute solders, since it is almost impossible to retain all of the desired qualities of a high-tin solder and still make drastic changes in the alloy composition. Because of the expected uses of a general-purpose solder, it is necessary that it have properties, especially in regard to wet-tability, that will enable it to be used on the metals in common use. Basic Considerations The maximum liquidus temperature of a solder is determined by the particular application involved and the temperature that can be obtained by the source of heat. If a soldering iron is used, it must not only

Jan 1, 1945

Occasionally it is interesting, and sometimes useful, to review the past for early references to our industry, and to learn of the trials and travail passed through before it arrived where it now is - and the results of such a review follow. Some time ago one of our modern playwrights and poets, Arthur Guiterman, turned to coal, with the following result : Afar in the Carboniferous time I grew in Paleozoical slime, A lepidodendron with boughs on my stem And lepidostrobusea grew out of them. My roots in the mud of the ages I spread And up to the heavens I vaunted my head, I throve in the heat of tropical sun, And now I am coal at two dollars a ton.

Jan 1, 1935

By T. R. Graham, R. G. Feustel, J. R. Long, R. S. Dean

The comprehensive study of the copper-manganese-zinc alloy system in the Bureau of Mines Laboratories has so far been principally concerned with alloys that lie within the alpha solid solution field of the system. Two regions, one centering about 65 per cent copper, 10 manganese and 25 zinc, and the other centering about 70 per cent copper, 20 manganese, 10 zinc, have been carefully examined. These have indicated that when the alloys are made with electrolytic manganese considerable amounts may be readily introduced and that the strength and hardness are increased without excessive losses in ductility. In the course of the work of establishing the limits of the alpha solid solution range,3 enough of certain of the alloys was prepared to permit determination of their- physical properties at a future date. The 60 per cent copper alloys concerned here are part of that series. They cross through the alpha field and into the adjacent alpha plus beta and alpha plus X fields, and are of interest because they offer some information on the effects of manganese on alloys lying in these fields. Composition and Fabrication of Alloys The chemical composition of the alloys involved is given in Table I. They were intended to contain 60 per cent copper with manganese increasing from 5 to 25 per cent in 5 per cent steps and zinc decreasing from 35 to 15 per cent. The analyses are so close to the intended composition that the alloys mill be referred to hereafter by their norninal compositions. They were finished into sheet by cold-rolling and intermediate annealing procedurzs calculated to produce sheet $i6 in. thick, cold-reduced by 20, qo, 60, and 80 per cent in thickness. Physical properties were determined on standard flat tensile specimens with 4-in. gauge length, although the test gauge section used was 2 in. The properties were obtained on cold-worked material and on material annealed at temperatures ranging from 700' to r500°F. after 60 per cent cold reduction. Since an annealing temperature of 1200°F.

Jan 1, 1946

By J. R. Long, T. R. Graham, R. G. Feustel, R. S. Dean

The comprehensive study of the copper-manganese-zinc alloy system in the Bureau of Mines Laboratories has so far been principally concerned with alloys that lie within the alpha solid solution field of the system. Two regions, one centering about 65 per cent copper, 10 manganese and 25 zinc, and the other centering about 70 per cent copper, 20 manganese, 10 zinc, have been carefully examined. These have indicated that when the alloys are made with electrolytic manganese considerable amounts may be readily introduced and that the strength and hardness are increased without excessive losses in ductility. In the course of the work of establishing the limits of the alpha solid solution range,3 enough of certain of the alloys was prepared to permit determination of their- physical properties at a future date. The 60 per cent copper alloys concerned here are part of that series. They cross through the alpha field and into the adjacent alpha plus beta and alpha plus X fields, and are of interest because they offer some information on the effects of manganese on alloys lying in these fields. Composition and Fabrication of Alloys The chemical composition of the alloys involved is given in Table I. They were intended to contain 60 per cent copper with manganese increasing from 5 to 25 per cent in 5 per cent steps and zinc decreasing from 35 to 15 per cent. The analyses are so close to the intended composition that the alloys mill be referred to hereafter by their norninal compositions. They were finished into sheet by cold-rolling and intermediate annealing procedurzs calculated to produce sheet $i6 in. thick, cold-reduced by 20, qo, 60, and 80 per cent in thickness. Physical properties were determined on standard flat tensile specimens with 4-in. gauge length, although the test gauge section used was 2 in. The properties were obtained on cold-worked material and on material annealed at temperatures ranging from 700' to r500°F. after 60 per cent cold reduction. Since an annealing temperature of 1200°F.

Jan 1, 1946

By A. J. Bartlett

ISLAND Creek conditions are generally referred to as ideal; yet, as at all other properties, there are all known hazards of coal mining. The hardest of these hazards to combat is the human element. The basic thought in the minds of the management of these properties is to produce coal with the utmost safety, and it has impressed upon its supervisory force that it does not want a ton of coal unless it can be produced safely. This company has instituted a mine inspection department, which reports direct to the general manager, and all matters pertaining to safety come under the direction of this department. Through the medium of the inspection department, the management is kept in touch with the actual conditions existing in general at all mines. Inspections are made regularly and continuously; that is, at all times while the mines are in operation some sections of some mines are being examined. These inspections cover all active and inactive workings. Miners are con-tacted in their working places and other employees at their respective work. A thorough check is made to see that the state mining laws are complied with and that company safety rules are being observed. Night shifts receive the same attention as day shifts. All violations and dangerous practices are brought to the attention of the plant supervisory force with suggestions and recommendations; major hazards of emer-gency nature are taken up immediately with the management. Peri-odical inspections are also made of all tipples, preparation plants, dumping and hoisting equipment, to see that all machinery is properly guarded, and walkways and platforms properly fenced; conditions of equipment and mechanical defects are also reported. Reports of inspection are written in letter form and in such a manner as to give the management a picture-of the existing conditions at the time of inspection. Copies of inspection reports are forwarded; to the superintendents with the general manager's comments.

Jan 1, 1937

By R. S. Shoemaker, D. L. Harris

PST investigations into the possibility of concentrating the low-grade iron ores of the Gogebic Range in Wisconsin have been hampered by the complex association of the constituent minerals. In part the problem arises from the fact that the iron occurs essentially as two minerals, hematite and goethite, having nearly the same chemical composition but exhibiting different physical properties. Individual grains of these minerals are usually so small that the ore must be ground to a size finer than 325 mesh if substantial liberation of the minerals is to be secured. Appraisal of beneficiation tests on this iron ore requires, therefore, some method of determining quantitatively the contents of constituent minerals in the various products of the beneficiation. Because of the chemical similarity of the two iron minerals, chemical analyses do not provide a means of differentiation. Although the minerals are different physically, they are both opaque and friable, and as the ore must be ground to a very fine size for liberation to be secured, quantitative microscopic methods of analysis are extremely difficult at best. In an effort to overcome these analytical problems, a quantitative X-ray diffraction analysis method has been developed at the University of Wisconsin for the research program on iron ore beneficiation. The X-ray diffraction analysis of chemical compounds of crystalline form has proved of inestimable value for structure studies and rapid qualitative analytical purposes in a number of fields.' In some cases X-ray diffraction analysis has been found suitable for quantitative determinations. H. P. Klug2 found that quantitative procedures for quartz powders when mixed with calcium fluoride were reproducible within ±1.0 pct. Talvenheimo and White3 reported quantitative analyses of clay minerals to be accurate within 10 pct and also detected 1 pct of bentonite in 99 pct illite. In other investigations,'" powders of quartz and mica have been analyzed quantitatively with accuracies from 1 to 5 pct. A powder of tungsten carbide was analyzed similarly by Redmond7 and Rooksby8 reported the determination of small amounts (0.11 pct) of calcium oxide in magnesium oxide. In the most generally practiced use of X-ray diffraction, traces of the diffracted beam are recorded as lines on a film much as lines of elements are recorded on an optical spectrograph film. As with the spectrograph, the darkness of the lines denotes the amount of the constituent in the sample. If the film is replaced by a Geiger tube assembly and a graphic recorder or a scaling unit, the intensity of the diffracted beam can be registered as a peak on a chart or energy impulses per unit of time on the scaler. Several methods of quantitative measurement have been investigated and reported in literature. Klug2 used manual operation of the goniometer and a counting technique to determine the difference in counting rates at the diffracted angle and for the background. In another case3 the area under the recorded diffracted peak was the basis for the determination. In other instances the height of the recorded diffraction peak above background, measured while the goniometer was moving, has been the basis for the measurement. The sizes of particles most suitable for diffraction techniques are reported in the literature as follows: for tungsten carbide a maximum of 40 microns7 and for quartz a maximum of 5 microns.' Very fine sizes of crystals are known to cause a broadening of the diffused beams; hence some workers have set a lower limit of 0.1 micron for quantitative results. Guinier10 has indicated that broadening of the diffracted X-ray beam is not appreciable for crystallites larger than 0.02 to 0.03

Jan 1, 1956

By W. E. STOKES

COMPANIES operating airplanes have had a relatively prosperous year, permitting them gradually to re- place old types of equipment. The pre-eminence of American-made planes, engines, and accessories has been challenged, either by foreign designs or by domestic patterns that have, for one reason or another. been licensed for manufacture abroad.

Jan 1, 1938

By H. R. Banks

Pondering the action of a ball mill employed to carry on comminution from the product of fine crushing to the point where flotation, cyanidation or other concentrating methods are applicable, one wonders where this machine had its origin. When Henry Wadsworth Longfellow reiterated the observation of that older poet Von Logau, and wrote "Tho' the mills of God grind slowly, yet they grind exceeding small," he probably visualized the type of mill that was employed in medieval times for the production of flour, and can therefore not be considered as having gained admittance to the fraternity of millmen, on behalf of either poet. He does, however, make it quite clear that the efficiency of even these Mills of Destiny was low, and to that extent voices a characteristic of fine-grinding equipment that has been the bugbear of all metallurgical engineers. Principle of Ball Mill The principle of the ball mill probably is traceable to the action along the coast line of oceans or lakes, or in the mountain streams. Wave action on rocks and pebbles, close to the shore line, gives the potential energy to the grinding media, which, in their rolling and tossing, break down the sands, and the resultant "pulp" carried out from the shore is classified and settles out in sizes ranging downward to extremely he mesh. Surely, these are the real mills of God. If we allow our minds to dwell on the total tonnage that has been handled in this way, adding to the sands and clays at present in existence those enormous tonnages of metamorphosed sedimentaries we sense the vast quantity of rock that has been so reduced. Is it not likely, therefore, that the answer to the beginnings of pebble milling, and eventually ball milling, came through the perception of this natural mill by one of our engineering forebears? Methods of Grinding The relatively low return of mechanical input to a ball mill, in terms of useful work accomplished, has always intrigued me immensely. The potential energy absorbed by a ball raised to a high point in its path is apparently released with a very small return in useful work. Is the ball mill the most desirable means of he grinding, or is there some other method through which we can recover a reasonable amount of the energy input in terms of useful work? Some years ago, on his retirement, H. W. Hardinge was questioned as to his thoughts on the trend of fine-grinding equipment. As I recall, his prophecy at that time was that the most likely field for improvement in grinding media would be toward a charge of flat disks with some mechanical scheme to cause them to slide over each other. Undoubtedly, Mr. Hardinge went through the usual experience of the muller and bucking board, the customary introduction of the budding millman to his calling. I have often wondered, but have never got beyond the wondering stage, as to the

Jan 1, 1947

By H. R. Banks

Pondering the action of a ball mill employed to carry on comminution from the product of fine crushing to the point where flotation, cyanidation or other concentrating methods are applicable, one wonders where this machine had its origin. When Henry Wadsworth Longfellow reiterated the observation of that older poet Von Logau, and wrote "Tho' the mills of God grind slowly, yet they grind exceeding small," he probably visualized the type of mill that was employed in medieval times for the production of flour, and can therefore not be considered as having gained admittance to the fraternity of millmen, on behalf of either poet. He does, however, make it quite clear that the efficiency of even these Mills of Destiny was low, and to that extent voices a characteristic of fine-grinding equipment that has been the bugbear of all metallurgical engineers. Principle of Ball Mill The principle of the ball mill probably is traceable to the action along the coast line of oceans or lakes, or in the mountain streams. Wave action on rocks and pebbles, close to the shore line, gives the potential energy to the grinding media, which, in their rolling and tossing, break down the sands, and the resultant "pulp" carried out from the shore is classified and settles out in sizes ranging downward to extremely he mesh. Surely, these are the real mills of God. If we allow our minds to dwell on the total tonnage that has been handled in this way, adding to the sands and clays at present in existence those enormous tonnages of metamorphosed sedimentaries we sense the vast quantity of rock that has been so reduced. Is it not likely, therefore, that the answer to the beginnings of pebble milling, and eventually ball milling, came through the perception of this natural mill by one of our engineering forebears? Methods of Grinding The relatively low return of mechanical input to a ball mill, in terms of useful work accomplished, has always intrigued me immensely. The potential energy absorbed by a ball raised to a high point in its path is apparently released with a very small return in useful work. Is the ball mill the most desirable means of he grinding, or is there some other method through which we can recover a reasonable amount of the energy input in terms of useful work? Some years ago, on his retirement, H. W. Hardinge was questioned as to his thoughts on the trend of fine-grinding equipment. As I recall, his prophecy at that time was that the most likely field for improvement in grinding media would be toward a charge of flat disks with some mechanical scheme to cause them to slide over each other. Undoubtedly, Mr. Hardinge went through the usual experience of the muller and bucking board, the customary introduction of the budding millman to his calling. I have often wondered, but have never got beyond the wondering stage, as to the

Jan 1, 1947

By C. C. Nathan

Data are resented on the physical properties of five waxes obtained from fields in Texas and Louisiana in which "parafin" troubles are being experienced. The crude parafin was fractionated into three components, voluble in cold acetone, soluble in boiling acetone, and insoluble in boiling acetone. The acetone insoluble fraction was found to consist essentially of straight chain parafin hydrocarbons in the molecular weight range 525 to 700. Solubilities of the purified high molecular weight parafins were determined in a number of solvents. It was found that in hydrocarbon solvents, including crude oil, solubilities could be calculated satisfactorily by use of ideal solubility relations. In chlorinated, and oxygenated solvents, large deviations from ideal behavior were observed. These deviations could be partially correlated with the internal pressure of the solvent. INTRODUCTION A problem encountered in many producing oil fields is that of "paraffin" deposition. The problem refers to the deposition of material from the crude oil onto tubing, pumping rods, flow lines, or other material contacted by the crude. This problem has been recognized for nearly a hundred years, and numerous investigations have been reported on its causes and prevention or alleviation. One of the more comprehensive of such investigations was published by Reistle1 in 1932. A few of the salient findings of his report are briefly as follows: The term "paraffin" as used to describe this problem refers to the deposit of carbonaceous material which is not soluble or dispersible by the crude oil under the conditions where deposition occurs. The "paraffin" normally consists of high molecular weight paraffin hydrocarbons, both straight chain and branched, resins and asphaltic materials of undetermined nature, occluded oil and water, and possibly sand. In consistency, the deposit may vary from a soft, sticky material, to one which is hard and brittle. Deposits are usually black, although lighter colors are sometimes observed. Under the conditions of temperature, pressure, and crude oil composition occurring in the underground reservoir, the paraffin is in suspension or solution in the crude. As the oil flows to the surface, there is generally a reduction of temperature, pressure, and the amount of dissolved gases contained in the oil. Reduction of temperature and gas break-out were shown by Reistle to be factors causing reduced solubility of the paraffin in the crude. Thus, as the crude containing paraffin rises to the surface and flows to storage tanks at atmospheric temperature, the solubility of the paraffin may be exceeded. Deposition will begin at the point in the system where the temperature of the system falls below its cloud point, and continue as long as there is a further drop in the solution power of the crude for the paraffin. The severity of the deposition as well as the location of the bulk of the deposition, i.e., in subsurface or surface equipment, will depend on the amount of paraffin originally in the crude, the manner in which pressure and temperature of the crude

Jan 1, 1956

By S. Usui, I. Iwasaki

The adsorption mechanism of dodecylammonium acetate (DAA) on mercury in potassium fluoride solutions at natural, near neutral pH was investigated. Difler-ential capacity combined with electrocapillary measurements on a dropping mercury electrode were found to provide a sensitive and reliable approach. A shift in the electro capillary maximum (or the point-of-zero-charge) towards positive polarization of the surface due to the adsorption of amine indicated a specific affinity of dodecylammonium ion for mercury surfaces. The amine was shown to adsorb competitively with potassium ion on mercury. Through correlation of the adsorption density of the amine, calculated from the thermodynamic analyses of the electrocapillary curves, and of the diflerential capacity curves, the adsorbed state and the orientation of the amine at the interface were considered. The similarities and the differences in the adsorption behavior of the amine on mercury and on such ionic solids as quartz, silver sulfide, and silver iodide were evaluated. With the promise of flotation providing a cheap and large-scale process for the upgrading of low-grade ores and magnetic concentrates, the iron ore industry has made a sustained search over the years for a flotation reagent of general applicability and high selectivity. Having shelves full of commercial reagents already on hand and anticipating more, both the users and the suppliers are in need of an experimental approach sensitive enough to differentiate the individual characteristics in each group of reagents. Therefore, the adsorption behavior of various flotation reagents on mineral surfaces from aqueous solutions has been a subject of much investigation. The current view of adsorption based on the electrical double-layer theory is formulated on the assumption that certain ions in solution act as potential-determining ions. Their concentrations fix the potential drop across the double layer and their adsorptions govern the surface charge.' Two methods used to study the adsorption

Jan 1, 1971

By E. Hoek

INTRODUCTION Rock slope stability research has been in progress for the past four years at the Royal School of Mines in London under the sponsorship of a consortium of 23 companies* with interests in open pit mining. This paper reviews the principal aims and achievements of this research project. In order to assist the reader in following these details, the basic philosophy underlying the formulation and direction of this research project is discussed. DISTRIBUTION OF RESPONSIBILITY In open pit mining, the economic necessity of keeping waste rock removal to a minimum generally means that the mine slopes have to be excavated to the steepest possible slope angle. On the other hand, excessive steepening of these slopes can induce failures, which may negate the economic benefits that have been aimed at and which may also result in loss of life and damage to equipment. Consequently, where slope failures are likely to prove to be a problem, an evaluation of the stability of the slopes to be created should be included as part of the overall pit design. How is the stability of a rock slope evaluated? When this question was examined, during discussions on the research policy to be followed at the Royal School of Mines, it was clear that relatively few satisfactory techniques were available in a form that would be comprehensible and therefore useful to the practical mining engineer. It was recognised that the research project must be directed towards two distinct aims: a) The evaluation of existing techniques for rock slope stability analysis and the provision of new techniques where these existing methods were found to be inadequate and b) The presentation of the results of this evaluation and research in a form that would be useful to engineers without specialist training in rock mechanics. It was soon realized that a university based research team, however large and efficient, could not achieve these aims without the co-operation and assistance of mining engineers,

Jan 1, 1972

By T. A. Rickard

In a former paper* the writer has described the essential features of the general geology of the Cripple Creek region. In the present account it is intended to examine into the occurrence of the ores, the value of which has made this district the most important among existing American gold-fields. The production of Cripple Creek from its discovery, in 1891, to the close of 1901, has reached a valuation of fully $125,000,000. During the past year (1901) the output amounted to $17,285,470. In 1900 it was $18,174,681. The first discoveries, which led to the development of the district, were made in the spring of 1891, but it was not until 1893 that vigorous work was commenced. A great impetus was then given to the exploration for gold on account, of the sudden drop in the market-price of silver, caused by the closing of the Indian mints in the summer of that year. This induced an energetic population from the older silvermining camps of Colorado to go to the new gold-field, which was then beginning to attract attention. Prospecting, at first, was hindered by the comparative absence of outcrops, due to the fact that the surface of the hills is covered with a considerable thickness of shattered rock, resulting from the action of frost at a high altitude; but so much indiscriminate digging was done that a number of rich veins were uncovered, and this stimulated the search for others. The advanced condition of the mining industry of Colorado offered unusual facilities for exploration and reduction; progress was therefore rapid, with the result that the district soon achieved great prominence.

Jan 1, 1903