Search Documents

By Hansheinz Portisch, Harold Margolin

A surface expansion was found to occur sometime after etching in Ti-A1 alloys containing 9.5 to 12.5 wt pct Al. The structure formed, grew, and disappeared with tzrrze. The surface expansion was followed by microscope observations and interferometric and lattice parameter measurements. Activation energy measurements for the growth of the "expansion structure" and chemical analysis indicated that the phenomenon occurred as a result of hydrogen pzckup during etching. It is proposed that hydrogen initially enters octahedral sites of Ti3Al coherent with a Ti and later shifts to the tetrahedral sites. It is postulated that expansion occurs when hydrogen enters the tetrahedral sites. The expansion structure disappeared, it is proposed, because of diffusion of hydrogen from the surface into the body of the alloy and because of loss of coherency of Ti3Al. In examining Ti-A1 alloys, Ence and arolinl observed markings on the surface of specimens. These markings did not appear after electropolishing only, but rather appeared only after etching. The markings appeared to grow as a function of time after etching and later seemed to disappear. Although the markings had some similarity to precipitates, showing, frequently, a Widmanstatten type of arrangement, the observation that other microstructural markings continue to be seen within the new structure suggested that it was actually not a precipitate. The source of this structure was unknown and an attempt was made in the present investigation to develop some understanding of its nature. It has been labeled expansion structure. 1) EXPERIMENTAL PROCEDURE A) Alloys. Alloys in the range 6.5 to 14.5 wt. pct A1 were studied. Bars, 4 in. sq, forged from Bureau of Mines (73 Bhn) titanium consumably arc-melted 4-lb ingots,' as well as 50-g arc-melted buttons of desired aluminum contents were used. The 50-g buttons also used Bureau of Mines titanium (73 Bhn) and aluminum of 99.99 pct purity. Buttons containing up to 8.5 wt pct A1 were hot-rolled from a furnace at 900' . Those with higher aluminum contents were hand-forged on a titanium anvil, and heated with an oxygen-hydrogen torch in the region of 1200" to 1300°c. Frequent reheating kept the samples at the desired temperature range. After a reduction of about 30 pct, the samples were water-quenched. To eliminate any contamination picked up either during hot rolling or forging, at least 1 mil of the surface of the sample was taken off. B) Heat Treatment. Prior to heat treatment all alloys were vacuum-annealed to remove hydrogen. Samples were annealed at 900' until a vacuum of 10'5 mm Hg was established. After this treatment, the samples were wrapped in molybdenum sheet and heat-treated in argon-filled quartz capsules, which were broken under water or iced brine at the conclusion of the heat treatment. All heat treatments under dynamic vacuum were performed in a rapid-quench furnace. This consisted of a molybdenum-lined quartz tube attached to a vacuum system and through a stopcock to a beaker of water. At the completion of the heat treatment the vacuum stopcock was closed, the furnace shut off, and dropped below the quartz tube. Then immediately the inlet stopcock was opened and water admitted until the tube was filled. The steam formed was allowed to escape through the inlet stopcock. This method was used in heat treatments up to llOO°C. C) Metallography. Specimens for metallographic examination were ground, then electropolished using a Disa Electropol machine with a perchloric acid electr01te. Specimens were etched with R-etch.3 A standard etching time of 3 min was used, with the specimen being agitated during immersion. D) Sample Preparation for X-ray Analysis. Samples 0.2 to 0.5 mm in diam were produced from heat-treated rods which were turned to 2 mm diam on a lathe and then rotation-etched. An etchant consisting of 1 pt HF, 7 pt HN03, and 12 pt HzO was satisfactory. With the rod rotating in a vertical position at 50 to 100 rpm, a needle with uniform dimensions could be obtained. Care had to be taken to insure that the rod was at the center of rotation, otherwise cavitation developed. If a small unevenness developed, it was possible to grind it off with a fine emery paper. E) X-ray Diffraction. All X-ray work was done on a North American Phillips X-ray diffraction apparatus and a Jarrell Ash microfocus X-ray unit. The Phillips unit was used with a copper target and nickel filter. The Jarrell Ash unit was fitted with a cobalt target and iron filter. For the Phillips unit 35 kva and 20 ma were used, whereas for the microfocus unit with the 100-p fixed-focus gun 40 kv and 1.5 ma were used. It was found that alignment of cameras on the Jarre11 Ash unit was very critical. The X-ray beam contains an intense area which is not the beam center. The cameras were aligned with the intense region by monitoring the beam coming out of the camera with a Geiger counter. Adjustments were made until a maximum intensity was obtained. A Phillips diffractometer with a Brown chart recorder furnished some of the lattice parameter data. The divergence slit up to 80 deg 28 was I deg; above 80 deg, a 4-deg opening was used, while the scatter slit was1 deg and the receiving slit had a 0.003-in. opening. The general scanning rate was 1 deg per min, while peaks of special interest were rescanned at -j deg per min. For elevated-temperature X-ray diffraction a Uni-cam High Temperature Camera with a film diameter

Jan 1, 1969

By John Jermain Porter

In taking up this subject it is first necessary to define our terms. Efficiency, in its engineering usage, means the ratio between actual and theoretical results, and efficiency-records thus involve the use of scientifically determined standards with which all results are compared. Scientific management is the methods used in increasing efficiency, and includes the use of efficiency-records. Efficiencj-records do not alone constitute scientific management, but they are necessary to it, and any so-called system of management which is not based upon standards and standardization is fundamentally wrong. An efficient management and efficiency-methods in management are not the same thing. There are some people who have an instinctive genius for management and accomplish results without exactly knowing how they do it. Such a manager may obtain a very high efficiency without the aid of scientifically determined standards. On the other hand, it sometimes happens that poor results will accompany the use of efficiency-recorcis, due to a weak or indifferent management, which fails to make use of the information acquired. Efficiency-records are only a tool, and like other tools are worthless unless used. The ordinary cost-sheet and production-statement do not go far enough. They tell what has been done, but give no information as to how well it has been done. It is true that the man who is familiar with the industry and the plant in question may draw inferences and form a general idea of good work or bad work, but it can only be a very general and hazy idea. Comparisons with previous records or records of other plants are unsatisfactory, since there is nothing to show the cause of the differences. Efficiency-records supply this need. They compare actual

Jan 1, 1913

By G. S. Brooks

The tendency of the oxides of such metals as aluminum, zinc, chromium, and calcium to form compounds at high tempera tures with iron oxide is well established by past investigation. Data of this reaction, as developed in laboratory research, have been contributed by Burleigh, Hofman, and Wells, in America, and by many others abroad. A partial bibliography of the subject is appended. From these authorities we learn that the ferric oxide here has the function of an acid, giving in the case of ZnO a zinc ferrite, with a normal composition of ZnOFe2O3 This formation of zinc ferrite particularly affects the success of such processes as leaching or magnetic separation, and thus becomes practically important to the metallurgist. But the meager existing data do not entirely agree; and quantitative results from muffle-practice are conspicuously absent. Furthermore, it being of some general importance to the zinc smelter in both roasting and reduction, the following few notes of operations oil a commercial scale are contributed: I. Physical Properties of Zinc Ferrite. As formed for the most part synthetically by investigators, zinc ferrite exhibits characteristic physical properties, such as octahedral crystals, dark color, and a density over 5, together with a slight magnetic attractability. In examining with the microscope many products of mechanical muffle-roasting kilns, it is, however, impossible to find individual grains which can be identified as consisting entirely of zinc ferrite. The variety of colors, especially where each grain of blende was mechanically free from marcasite, rather conveys the impression of a partial ferritization of the grain. One side or end, for example, may often have the hard, dense surface and dark red to black color of the ferrite, while the balance shows the usual light yellowish brown of a normal iron-free blende.

Jan 1, 1914

By B. G. Ricketts, A. Kelly, P. A. Beck

The isothermal kinetics (at 200" to 400°C) of subgrain growth and of softening were studied in a 99.997 pct pure Al crystal rolled to 80 pct RA, under conditions where recrystallization did not take place. It was found that the kinetics of subgrain growth and of softening were similar, and that the correlation between subgrain growth and softening was in first approximation independent of the annealing temperature. It has been shown by Heidenreich' by means of electron transmission microscopy and by Hirsch and Kellar2 by means of an X-ray microbeam technique that the crystals of heavily cold-worked polycrystalline aluminum consist of subgrains of approximately 2µ diam, which are slightly disoriented with respect to each other. This substructure is found on cold working at room temperature, without annealing. A preliminary study has been previously published3 of the softening upon annealing at 350°C of a heavily cold-rolled aluminum single crystal. Softening and X-ray line sharpening for such a rolled aluminum crystal were later studied in more detail as a function of annealing time and temperature.4 Perryman5, 6 has studied the recovery of polycrystalline aluminum after cold rolling. By means of phase contrast microscopy he found that the subgrain size increases with the annealing temperature but does not alter very much with annealing time at a given temperature. In the present work further study was made of softening as a function of annealing time and temperature and subgrain sizes were determined by two different techniques in an attempt to find any correlation that may exist between softening and subgrain growth. Subgrain size measurements were made both by the X-ray microbeam technique and by transmission electron microscopy. EXPERIMENTAL PROCEDURE For the X-ray studies specimens were cut from

Jan 1, 1960

By Forrest F. Craig

Both early and more recent1 laboratory measurements of gas-oil relative permeabilities were made by subjecting oil-saturated cores to external gas drives. In these runs it was generally assumed that the flowing gas/oil ratio was constant at every point throughout the core. Using this assumption, the resulting equation for the gas-oil relative permeability ratio becomes A where Q is the flow rate at the producing end of the system. This relative permeability was then specified for the average saturation of the core. The assumption and resulting equation fail to recognize that in an external drive, the oil flow rate varies from zero at the injection end to a maximum at the producing end. The assumption also fails to consider the existence of a saturation gradient during an external drive. This saturation gradient is due solely to non-steady-state flow. Some authors2,3,4 have used this erroneous method of calculating relative permeability ratios from external drives. Other authors5,6,7 have used relative permeability ratios in calculating expected field performance by external drive, using Equation (1) and making the incorrect assumption that the saturation is uniform within the driven portion of the reservoir. To find the correct relation between the relative permeability. ratio at the average saturation and the produced gas/oil ratio, the insertion in Equation (1) of a factor, F, to adjust it for oil velocity gradient has been considered. The equation then takes the form Assuming that the oil velocity is directly proportional to the distance from the injection point leads to the conclusion that, for a linear system, the average oil velocity is one-half that at the producing end. Thus, the average gas/oil ratio is twice the produced gas/oil ratio, and Equation (2) is transformed into However, here again the existence of a saturation gradient is not recognized. The produced gas/oil ratio is related to the relative permeability ratio at the saturation of the outlet end of the system. It can be shown quite readily that, if the true log k,/k, saturation relationship is linear over small ranges of saturation, then d log kjko Where aaxv and u2 are the average and outlet saturations, respectively. Examination of Equation (3) shows that the factor F cannot have a single value over the whole saturation range. Another method of dealing with external drives is that of Buckley and Leverett.' Their method, which assumes no gas expansion and outlet end effects, considers fully the saturation gradient present due solely to the displacement mechanism during an external drive, and applies Equation (1) to each point along this gradient. The calculation of production history using relative permeability ratio is straightforward. However, the calculation of relative permeability ratios from production history by this method is impractical. In a recent paper, Welge,1 using an approach similar to that of Buckley and Leverett, presents a simplified method for determining the saturation at the producing end of the system. At thi; saturation, the relative permeability ratio calculated by Equation (1) applies exactly, after breakthrough of the stabilizej front. By this method, relative permeability ratios or production history may be calculated with equal ease. Use of this method as a laboratory tool in determination of relative permeability ratios by external drive requires the knowledge of the total injected fluid volume; in addition to the average saturation and producing ratio. As a preliminary test of this method of calculation, laborntory external gas drives were run on a 3% in. diameter, 11 in. long sample of Nellie Bly consolidated sandstone. This core sample had a permeability of 824 md and a porosity of 28.1 per cent. The driving fluid was air. Three different oils were used, having viscosities of 1.4, 9.8, and 125 cp, respectively. The runs were made under identical pressure differentials,

Jan 1, 1952

By W. R. Crane

DRAINAGE in these mines has been discussed in papers, on mining practice,1 but the fact that water, varying from 0.16 to 3.46 and averaging 1.43 times the amount of ore mined, has to be pumped from the mines daily, indicates the importance of the problem and the advisability of making a thorough investigation of the source of mine water, its mode of entry into the mines, its effect upon mining conditions; and consideration of means of improving the conditions. While conditions are not serious, yet there is danger that they may become worse if present mining practice is continued, owing to the presence of formations, known to carry large quantities of water, that overlie the ore bed worked. Much detailed information has been collected regarding: rainfall, and run-off in streams draining the district; the effect of different kinds of formations, porous and non-porous; the inclination of the surface; the condition of the surface above the mines, i. e., whether or not disturbed by ground movement; the occurrence of the ore and character of associated formations, particularly with respect to presence of jointing or slip planes, faults, etc.; failure of top rock in the old stopes; and the conditions under which water effects entrance into the mines, i. e., whether as a natural or forced flow. The study furnished fundamental data on the source of waters now entering the mines and that which may later enter due to collapse of top formations in. abandoned workings. The presence of jointing, or slip planes, has a pronounced influence upon the whole drainage problem. These present lines of least resistance to the water and, by weakening the top formations, cause fracturing of the overlying rock, allowing both surface and deep-seated waters to enter the mines.

Jan 1, 1927

By V. C. Allison

The explosibility of a dust is favored by its fineness and content of volatile combustible matter; its explosibility is decreased by its moisture and ash content. The explosibility of a dust can be reduced by admixture of either inert dust or water. The major effect of both the inert dust and water lies in their heat capacity; they absorb the heat of the explosion flame until the temperature of this flame drops below the ignition temperature of the explosive heat. The amount of inert dust necessary to make an explosive dust non-explosive can be calculated from its proximate analysis. FOREWORD LARGE-SCALE testing of the explosibility of coal dust as conducted by the Bureau of Mines in its Experimental Mine involves a large initial investment, and a high charge for maintenance and conduct of the test; in addition the work is necessarily slow because of the time required for the preparation of the tests and the cleaning and repairing of the mine after each test. These tests have been made along practical mining lines that admit of a range of mixtures of dust varying from 5 to 10 per cent. and with gas as low as 0.5 per cent. increments. Because of the time and expense involved, efforts have been made to devise a type of gallery for laboratory use in which the results obtained in the Experimental Mine may be correlated as an aid in a study of dusts, the explosibility of which might be approximately determined quickly and at a minimum of expense. The explosibility of coal dust has been studied by a number of European investors, using small laboratory devices; among these may be mentioned the experiments con¬ducted by Galloway, Vital, Hall and Clark, Abel, Mallard and Chatelier, Thorpe, Bedson and Widdas, Engler, Holwartz and Meyer, and Taffanel, results of whose experiments have been reviewed by the Bureau of Mines., The Bureau has conducted many tests with the Frazer-Clement2 apparatus, which gives the pressures set up when the dust cloud within is, ignited with a platinum coil or tube, heated to different temperatures, but for these tests the sample must be especially prepared as to size (200 mesh) and must be dry. An attempt has been made to design an apparatus that may be used for checking and correlating the experimental tests. The first design was a wooden gallery, 8 by

Jan 7, 1925

By Graham P. Crutchfield

The W. I. Cook pool in Shackelford County, Texas, has been the subject of a number of papers and articles. Its unique position both as to operation and development has made it an ideal location for unit repressuring. The major portion of the pool is located on the W. I. Cook ranch and most of the oil leases are owned by Roeser & Pendleton, Inc. and the Continental Oil Co. and operated by Roeser & Pendleton, Inc. The Humble Oil & Refining Co. and Tom James operate producing leases which have a vital bearing on the unity of the pool. Both have cooperated in the repressuring project. Practically the entire royalty is owned by Mrs. W. I. Cook and she has given the operators her entire cooperation in all phases of unit repressuring.

Jan 1, 1931

By R. Ehrlich, F. E. Crane

A consolidated porous medium is mathematically modeled by networks of irregularly shaped, interconnected pore channels. Mechanisms are described that form residual saturations during immiscible displacement both by entire pore channels being bypassed and by fluids being isolated by the movement of an interface within individual pore channels. This latter mechanism is shown to depend strongly on pore channel irregularity. Together, these mechanisms provide an explanation for the drainage-imbibition-hysteresis effect. The calculation of steady-state relative permeabilities, based on a pore-size distribution obtained from a Berea sandstone, is described. These relative permeability curves agree qualitatively with curves that are generally accepted to be typical for highly consolidated materials. In situations where interfacial effects predominate over viscous and gravitational effects, the following conclusions are reached. 1. Relative permeability at a given saturation is everywhere independent of flow rate. 2. Relative permeability is independent of viscosity ratio everywhere except at very low values of wetting-phase relative permeability. 3. Irreducible wetting-phase saturation following steady-state drainage decreases with increasing ratio of nonwetting- to wetting-phase viscosity. 4. lrreducible wetting-phase saturation following unsteady-state drainage is lower than fir steady-state drainage. 5. Irreducible nonwetting-phase saturation 101lowing imbibition is independent of viscosity ratio, whether or not the imbibition is carried out under steady- or unsteady-state conditions. Experiments qualithtiveIy verify the conclusions regarding unsteady-state residual wetting-phase saturation. Implications of these conclusions are discussed. INTRODUCTION Natural and artificial porous materials are generally composed of matrix substance brought together in a more or less random manner. This leads to the creation of a network of interconnected pore spaces of highly irregular shape. Since the geometry of such a network is impossible to describe, we can never obtain a complete description of its flow behavior. We can, however, abstract those properties of the porous medium pertinent to the type of flow under consideration, and thus obtain an adequate description of that flow. Thus, the Kozeny-Carmen equation, by considering a porous medium as a bundle of noninterconnecting capillary tubes, provides an adequate description of single-phase flow. With the addition of a saturation-dependent tortuosity parameter in two-phase flow to account for flow path elongation, the Kozeny-Carmen equation has been used to predict relative permeabilities for the displacement of a wetting liquid by a gas. 1-5 It has long been recognized that relative permeability depends not only on saturation but also on saturation history as we11.6,7 Naar and Henderson8 described a mathematical model in which differences between drainage and imbibition behavior are explained in terms of a bypassing mechanism by which oil is trapped during imbibition. Fatt9 proposed a model for a porous medium that consisted of regular networks of cylindrical tubes of randomly distributed radii. From this he calculated the drainage relative permeability curves. Moore and slobod,10 Rose and Witherspoon,11 and Rose and Cleary12 each considered flow in a pore doublet (a parallel arrangement of a small and large diameter cylindrical capillary tube). They concluded that, because of the different rates of flow in each tube, trapping would occur in one of the tubes; the extent of which would depend upon viscosity ratio and capillary pressure. They limited

Jan 1, 1970

By Verne D. Johnston

ALTHOUGH the stocks of Lake Superior iron ore on dock or at furnaces at the beginning of the year were about 6,000,000 tons less than at the beginning of 1938, the steel industry was operating at only 52 1/2 per cent of capacity and continued at approximately this rate to about Aug. 1. Consequently the iron mines in the Lake Superior district during the winter and spring period were almost all on a curtailed production basis, governed mostly by the needs of the communities rather than by anticipation of ore demands. Many of these properties gave extra employment by prosecuting heavy strip- ping programs, and the underground mines by shaft sinking and rock development. All underground mines re- turned to full operation in September, mostly two-shift, five days per week. A few operated the sixth day. The ship- ping schedules were increased so that the actual delivery for the year exceeded early expectations by about 20 per cent. Final Lake shipments were slightly in excess of 45,000,000 gross tons.

Jan 1, 1940

By Charles L. Mantell, B. G. Shah

SINCE the beginning of the industry, commercial electrolytic manganese has followed the Shelton patent' among others, which called for the addition of sulfur dioxide in controlled amounts, to a purified manganese sulfate-ammonium sulfate at a controlled pH. Every attempt to eliminate sulfur dioxide additions has resulted in operating difficulties, chiefly solution of the deposited metal and lowered current efficiencies. Many replacements for sulfur dioxide have been proposed and studied, chiefly sulfur compounds, urea, thiourea, and proteins similar to those employed successfully in copper refining. It has been suggested that sulfur dioxide is a re-ductant for higher-valence manganese compounds, or that it is reduced by manganese metal in the deposit to hyposulfites or its compounds, and that these might affect the cathode film or the deposition potential, or the overvoltage of manganese. The additives were studied following the method of Mantel1 and Ferment2 who determined the feasibility of current-potential curves as an analytical tool for monitoring manganese elec trowinning solutions for metallic impurities: nickel, cobalt, silver, copper, zinc, molybdenum, cadmium, magnesium, and sodium. The individual effect of each on the standard polarization was determined for a range of concentrations. Not all affected the polarization curve; cadmium, magnesium, and sodium had no effect. Nickel, cobalt, silver, copper, and zinc yielded a correlation between transition current and concentration of impurity.

Jan 1, 1968

By M. J. Scoble, W. J. P. Leigh

This paper aims to characterise the forms of slope instability incident in surface coal mines in Britain. These are related to observed controlling factors, with particular reference being given to slope geometry and structure. The work is based on specific data collection programmes considering actual stable and unstable mine slopes. Reference is made to field examples.

Jan 1, 1982

By Jack Fox

Three years ago we attended the V International Mining Congress in Moscow. This year we attended the VI International Mining Congress in Madrid. By almost any criterion, this was a most successful convention. There were 1717 registrants, not counting the ladies. I don't know how many of the latter there were, but they certainly made a welcome addition to the group. Once again, the International Organizing Committee put together a very impressive technical program which the Spanish National Committee backed up with a brand new Palacio de Congresos admirably equipped with simultaneous translation devices and an organization that provided an excellent social program, a tremendous set of post- meeting excursions, and very impressive opening ceremonies, entertainment and closing ceremonies. There was also an exhibit on the subject of Spanish and Spanish American mining history in the Palacio de Congresos.

Jan 1, 1970

By S. R. B. Cooke, R. O. Huch, C. S. Chang

IN the flotation of iron ores laurylamine derivatives have been used for considerable time.12 To effect satisfactory separation of the gangue, predominantly silica, from the iron oxide minerals, the addition of specific depressants for the iron oxides has been found necessary. Starches and starch products have been used for this purpose. 3 There is, however, very little published information on the effects of these materials and other variables on this process. In some cases it has been found that prior acid scrubbing and desliming are essential, 4 and depending upon the efficiency of the subsequent washing step, there will be accompanying changes in pH. It was the object of this investigation to test and observe the effects of the above factor as well as to examine and compare the action of various starches and starch products.

Jan 12, 1953

By S. Yukawa, M. J. Sinott

The low solubility of bismuth in copper and its segregation at copper grain boundaries with resulting embrittlement is well known.1-3 The heterogeneous diffusion of liquid bismuth into polycrystalline copper has also been studied.4 This work presents some further observations on these phenomena using high-resolution auto radiography to detect the presence of bismuth in copper polycrystalline and bicrystal specimens. The auto radiographs were made by the stripping film technique which produces an autoradiograph that is intact with specimen surface and can be examined simultaneously with the under-lying microstructure. The details of the technique have been described previously.3 In one series of experiments, high-purity copper was alloyed with 0.02 to 0.03 wt pct radioactive bismuth obtained from the Oak Ridge National Laboratory. Melting and casting was done under a

Jan 1, 1960

By Ferid Kromer

This paper is the first in a series which will describe geology, mining methods, and production costs of some of Turkey's more important minerals. In this paper the economically significant minerals-chromite, meerschaum, and magnesite-of the Tastepe district are described. The cost data presented are believed by the author to be the first made public on Turkish chromite mining.

Jan 1, 1950

By Hannu Penttila, Harrison R. Cooper, Olli Mattila

Two approaches to automated operation in metallurgical processes involve the conventional analog control or, more recently, digital control. The expanding use of digital controls applied to process automation is a comparatively new development. Several current technical reports describe digital control systems in concentrator grinding control, 1, 2, flotation, 3 and smelter operations. 4,5 The principle factors influencing trends to digital control are:

Jan 10, 1976

By Walter O. Snelling

In combating mine-fires the use of carbon dioxide as a means of producing an atmosphere in which combustion cannot be sustained, has been many times suggested and frequently tried, generally with a fair degree of success. The carbon dioxide is produced by acting on limestone with dilute sulphuric acid, large wooden boxes being used to hold the limestone, and arranged in such a manner that one box may be cleaned and refilled with blocks of limestone while another is being used in generating the carbon dioxide.. The gas is led by means of pipes of large diameter to the location of the fire, tight brattices having been previously put up as close to the fire as possible on every side, so as to limit the space to be filled with the gas to the smallest possible volume. The cost of producing carbon dioxide has been, however, a decided draw-hack to the use of this method, and the danger of producing carbon monoxide by the reduction of the carbon dioxide by heated carbon, and consequently bringing about an explosion, has also tended to prevent the application of this method. The use of sulphur dioxide in combating mine-fires has not, I believe, been previously suggested or tried, and yet the method presents such decided advantages over the use of carbon dioxide that it seems proper to suggest the advisability of considering it as a cheap, convenient, and safe means of fightr ing stubborn mine-fires. 1. Cost, Preparation, etc.—One ton of brimstone, costing from $20 to $30, will produce about 25,000 cu. ft. of sulphur dioxide gas, and allowing for all sources of loss it is probable that sulphur dioxide gas can be produced for about $1,300 per 1,000,000 cu. ft. For carbon dioxide gas, produced by the action of sulphuric acid on limestone, a good estimate would be $4,000 per 1,000,000 cu. ft., provided that sulphuric acid

Jan 1, 1909

By H. W. Camp

The past year has had no revolutionary change in the process of petroleum refining, although there have been improvements and developments in practically every phase of operation, due largely, perhaps, to economic pressure. A few years ago, a Mid-Continent skimming plant using 35 gravity crude obtained 28 per cent. gasoline and naphtha; 9 per cent. kerosene, and the remaining yield gave gas oil and fuel oil. Figuring manufacturing cost, but not including sales, transportation, overhead and depreciation, the realization was $1.45 per bbl. of crude. Today, a thoroughly modern and up-to-date skimming plant, having all latest equipment, shows a realization of $1.74 per bbl. on the same basis. Thus it is evident that progressive developments have taken place in the last 2 or 3 years when potential earnings have been increased about 20 per cent. The average refiner is compelled to exert his utmost ingenuity in order to operate with a profitable margin. He has two factors to consider—recovery of maximum yields of profitable oils and the reduction of operating expenses. For the past 8 years, the margin between price of gasoline and cost of crude has grown narrower, constantly. Both these prices are determined by external conditions and not by the refiner himself, but the refiner might have been able to increase that margin had he more carefully controlled his output, limiting his production of light oils to current consumption. Be that as it may, this same economic pressure has given impetus to progress in improvements of primary distillation equipment, including stills, towers and heat-saving devices. A pipe still and bubble cap fractionating equipment can now replace a battery of shell stills, giving better yields, better control, elimination of rerunning and lowering of operating costs. The most recent pipe stills are being equipped either with radiant-heat furnaces or air-preheating systems and improved heat exchange equipment. These can be operated on a fuel consumption as low as 1 per cent. of the charge as compared to a fuel consumption of

Jan 1, 1929

By Sir Robert Hadfield

Table 1 gives the composition of the specimens listed by the author. The details of test procedure and the results of the tests on mechanical, magnetic and electrical properties and cor-rodibility of the alloys are published in full in a paper by the same author, "Alloys of Iron and Manganese Containing Low Carbon," presented before the Iron and Steel Institute (of Great Britain) and published in full in their Proceedings for 1927, to which reference should be made. After reporting these tests the author gives the following discussion of results:] The studies here reported do not indicate that any of the series has really valuable or useful qualities for industrial applications, though the demands of industry are so varied that it is unsafe to prophesy that no special use will be found for a given material. The non-magnetic property of manganese steel is due to the association of Fe and Mn, but carbon has also an effect, enabling non-magnetic qualities to be obtained with a much lower percentage of Mn than would otherwise be the case; for example, 16 per cent. Mn is necessary for alloys practically free from carbon, while with 1 per cent. C nonmagnetic alloys may be obtained with as little as 7 per cent. Mn. Carbon, however, is the prime cause of the development of magnetic qualities by heat treatment. (Sec section 8 of the paper referred to above.) These Fe-Mn alloys show a resistance up to 87 microhms per c. c., but. as there are other alloys which have a resistance as high as 130 microhms per C. c., this does not provide any new feature of value. The most marked feature of the series studied is the brittleness in the range 3 to 10 per cent., with a maximum of brittleness at 7 per cent. Material with this percentage, while possessing quite appreciable hard-

Jan 1, 1927