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By T. L. Joseph

BLAST furnaces are most efficient thermally when the C02 in the top gas is highest. Oxygen introduced in the air blast is converted to CO in the combustion zones. The extent to which CO, generated in front of the tuyères, is converted later to C02 depends upon the ratio of ore to coke in the charge and the degree to which C02, formed by reduction of iron oxides with CO, reverts to CO by the secondary reaction C + C02 = 2C0. About 300 to 400 lb. of carbon1 per ton of pig iron is normally involved in the solution-loss reaction or direct reduction of FeO with carbon, which produces the same over-all results; that is, lower C02 in the top gas. Riche has recently reported a reduction in fuel consumption at slower rates of blowing on two furnaces in spite of higher heat losses per ton of iron. Lower fuel consumption at slow operating rates was due to more complete reduction of the ore that resulted in higher C02 in the top gas and consequently more efficient use of carbon. Kinney3 has reported substantial savings in fuel as a result of crushing and sizing the ore charge. Improvements in practice brought about by sintering magnetite concentrates, flue dust and fine ores have been due to the establishment of conditions favoring more complete reduction of the ore in the upper part of the furnace. The extent to which oxides and fluctuations in composition in pig iron affect the quality of steel and finished product needs further study. There is evidence that more thorough preheating and reduction of the ore in the upper part of the furnace tend to give a better quality of iron. Bogatzkii4 found from laboratory work that the amount of oxygen enter-

Jan 1, 1936

Operating Characteristics of Centrifugal Fans and Use of Fan Performance Curve Discussion of paper by. Louis W. HUBER, presented at the New York Meeting, 1926, .and issued, as Pamphlet No. 1542-A, with MINING AND METALLURGY, February, 1926. G. BRIGHT, Pittsburgh, Pa.-Apparently from the pressure curves for a forward-curved-blade fan, in Mr. Huber's paper, practically all ventilation-might be stopped with increased resistance. In order, to discuss the characteristics of a fan we need, some better way to measure the characteristics of a mine. You all know that. the average anemometer is not very-reliable. Sometimes two anemometers, supposed to be recently calibrated, will differ 50 per cent. Either this or some other committee should standardize measuring methods. The characteristic curves of fans, given by Mr. Huber, would indicate that the forward-curved-blade fan would cause trouble in attempting parallel operation, because two machines will not parallel unless they have dropping pressure characteristics. On the other hand, it is indicated that with the backward-curved blade, they could easily be paralleled. But few mines use more than one fan. Mr. Huber said that if the resistance of the mine was considerably more than contemplated, the quantity of air might be such that the efficiency of the backward-curved fan would be seriously affected, dropping say from 70 to 55 or 50 per cent. In such event, could a difference of speed be selected for the fan that would give the quantity desired at a higher efficiency? L. W. HUBER, Pittsburgh, Pa.-The backward-curved-blade fan responds to change in speed the same as any other fan; if' the speed is doubled, the quantity of air is doubled, the pressure is increased four times and the horsepower eight times. One point not mentioned in the paper is that the backward-curved fan is more efficient than the forward-curved or any other type. If the latter were more efficient, it would pay to install that type and keep the resistance of the mine constant, which is hard to do but it can be done with care. But the total mechanical efficiency of a fan with backward-curved blades is from 10 to 20 per cent. higher.

Jan 1, 1927

By Floyd C. Kelly

There is an ever-increasing demand for furnaces with controlled atmosphere, due to the large quantities of steel being used in the automotive industry, such as the high-chromium stainless irons, the 18 Cr, 8 Ni stainless iron and low-carbon steel sheets. The difficulties involved in the annealing of such materials, if they are to be kept absolutely free from oxidation, are many. It is possible to bright-anneal these steels in small laboratory hydrogen furnaces, using specially purified hydrogen and taking some additional precautions. In the first place, the insulation, usually of alumina or magnesia, holds small amounts of water vapor, which it is almost impossible to remove completely. Secondly, there is always condensataion of water vapor in the cooling chambers of such furnaces, and with the continuous circulation of the hydrogen gas in the furnace, the water vapor is carried from the cooling chamber back into the heating chamber. This water vapor oxidizes the charge. Lastly, the supply of moisture is made sure by the diffusion of small amounts of air from the atmosphere into the furnace against the pressure of the hydrogen. The oxygen combines with the hydrogen and forms more water. Under such conditions there is little gained by using specially purified gas, because it becomes contaminated after reaching the furnace. Low-carbon Steel If a sheet of low-carbon steel is annealed in such a furnace at 750" C. and allowed to cool with the furnace, an adequate flow of purified hydrogen being maintained all of the time, the steel will come out with a very thin coating of blue oxide. If a similar sheet is annealed at the same temperature and quickly pushed into the cooling chamber, it will come out nearly bright, or perhaps with only the edges slightly discolored. It is difficult to get a piece of steel through a furnace of this type with an absolutely bright surface. This is due to the fact that there are always traces of oxygen or water vapor in the furnace. When the steel is allowed to cool with the furnace, it reaches a critical temperature where the affinity of iron for oxygen is greater than that of hydrogen for oxygen, and the steel comes out discolored. If the steel is pushed from the hot zone

Jan 1, 1931

By Clarence Zener

IT has long been known that the density of a metal usually decreases with cold-work. Thus O'Neill1 observed as early as 1861 that cold hammering of commercial hot-rolled copper is accompanied by a decrease of density of 0.2 per cent, and that subsequent annealing restores the original density. The origin of this density change, however, has remained obscure. In particular, experiment has not yet decided whether it is due to the presence of small cavities and an increase in intergranular surface or to an actual expansion of the lattice itself. This uncertainty in the origin of the change in density is a reflection of our uncertainty as to the changes induced in a metal by cold-working. One school regards cold-working as a breaking up of the original grains into a large number of perfect crystallites somewhat randomly orientated with respect to one another.2 According to this viewpoint, the mere introduction of a large intercrystallite surface induces a net volume expansion. Another school regards cold-working primarily as a distortion of the grains. It is not obvious that this second viewpoint will lead to a net volume expansion. The purpose of the present paper is to show that this is indeed the case, and that this expansion is of the right order of magnitude to explain existing experimental data. The physical basis for the association of an expansion with distortion lies essentially in the variation of the elastic moduli with volume. This variation is considerable. Thus from Table I we see that a I per cent increase in volume for the case of copper will decrease the bulk modulus K by i0 per cent, the shearing modulus µ by 3.8 per cent. If we thus twist a rod through a given angle, we shall do less work upon it if it increases slightly in volume, thereby reducing the torsion modulus that involves as a factor the shearing modulus. A general principle' in physics states that the rod will so adjust itself as to have a minimum potential energy consistent with the end restraints. It will therefore expand. [ ] In order to obtain a quantitative comparison with experiment, we follow Maier4 in comparing the lattice expansion with the latent energy of cold-work. This latent energy has been measured directly by Taylor and Quinney5 on copper rods subjected to torsion, and may amount to as much as 15 per cent of the total work done upon the specimens. We shall assume that this

Jan 1, 1941

By George Otis Smith

That an oil-land law is the most needed item in the proposed program of mineral-land legislation follows from the fact that Congress has never enacted a law really applicable to petroleum and natural gas. The action of Congress in 1897 in authorizing entry of oil lands under the placer law, enacted 27 years before for the mining of gold in surface gravels, was plainly only makeshift legislation. Naturally the provisions of this placer law with its requirement of discovery as a prerequisite to location are nothing less than absurd when applied to petroleum deposits hundreds or thousands of feet beneath the surface. Other reasons which render oil-land legislation an urgent necessity arise first from the large acreage of lands believed to be valuable for their deposits of oil and gas and therefore withdrawn by Executive order from all entry pending the enactment of . an appropriate law for their disposition—a withdrawal that has been specially ratified by Congress in the case of one State, Utah—and second from the exceptional importance of this resource to the nation, the large industrial worth of petroleum, and indeed its paramount value to the navy, not being suspected 17 years ago when Congress last legislated upon this subject. Mineral land of this type is also well adapted to serve for purposes of illustration in discussing the general principles that demand recognition in legislative reform. Most of the issues involved in the consideration of oil-land legislation are clean-cut, and essential differences of opinion will be seen to be based upon radical divergence in economic theory rather than upon conflicting views concerning unimportant details. For the last five years or more the geologists of the Federal Survey have discussed this subject and prepared memorandums and reports on the various bills introduced in Congress. Most of the provisions suggested in the present outline have been under consideration at one time or another during that period, and many of the statements which follow can be said to represent the consensus of opinion among those of us who, both in the field and in the office, have given special attention to the public oil lands.

Jan 1, 1915

By Jos. J. Walsh

Ventilation within a coal mine is essential to the welfare of those employed therein, from the standpoint of health, safety, and efficiency. While the saving of life and the preserving of health are the chief reasons for ventilation, efficiency and production are increased. In spite of the fact that we speak of air as having a certain composition, the proportions of oxygen, nitrogen, and carbon dioxide are not fixed, but vary between small limits. The different elements are not chemically united, they are merely mixed and each is free and can be separated with little energy. For this reason air in the mine workings is seldom found in a pure state. Factors that necessitate ventilation in coal mines are those that change the composition of pure air. Contamination of mine air results from the burning of oil-fed flames, the use of explosives, the oxidation of coal, and the liberation of gases by the coal. The extent to which these factors exist governs the size and general plan of the ventilating applianccs required. An efficient ventilating system is one that will furnish air at the working faces in sufficient volume to dilute and render harmless noxious gases and at the same time maintain an oxygen content closely approaching that of pure air. In a well-ventilated mine, the oxygen seldom falls more than 0.5 per cent. below normal. The carbon-dioxide content of the air in the average coal mine will vary from 0.1 to about 0.8 per cent., which amounts are not harmful. Three per cent. of carbon dioxide in air doubles the frequency and the depth of breathing; it is plainly noticeable and if breathed continuously for several hours its effect would probably be harmful. Slight reductions in the oxygen content of the air, such as occur in well-ventilated mines, have no debilitating effect on the worker. A person not exerting himself would fail to observe any unusual physical effect in an atmosphere: containing 17 per cent. of oxygen. This condition, however, or even a condition showing an oxygen content below 20 per cent., would indicate poor ventilation and that the elements which tend to reduce the efficiency of the worker are present, namely water vapor and a high wet-bulb temperature.

Jan 1, 1923

By G. E. Tardiff, A. A. Hendrickson

THE objectives of this communication are to present the solid-solution strengthening data for silver-base zinc single crystals and to evaluate the importance of strength contributions from several mechanisms through the use of this data combined with that for the silver-base aluminum case.' Some features of the yield point behavior of silver-base zinc crystals were previously reported.' Silver-base zinc alloys were prepared by induction melting 99.99 pct Ag with 99.9 pct Zn in high-purity graphite crucibles contained in argon-filled quartz tubes. After the first melting, the ingots were cut into short lengths, redistributed in the molds, and remelted in order to reduce solute-concentration variations. Alloy single crystals were then grown from the melt through the use of a modified Bridgeman technique which consisted of lowering the graphite crystal mold through a hot zone at a rate of 3/8 in. per hr. As in the melting operation, the molds were contained in argon-filled quartz tubes. Gage lengths 2 cm in length were introduced by both spark machining (circular cross sections) and abrading and acid etching (rectangular cross section) followed by electropolishing (a comparison of the critical resolved shear-stress values prepared by the two techniques showed no differences in strength values). The final cross-sectional areas of the crystals were approximately 5 sq mm. Prior to testing, the crystals were annealed at 600°C for 20 hr in argon atmospheres, furnace-cooled, and lightly electropolished. Crystal orientations were determined using the back-reflection method. The tensile testing was done on a Model FM Instron at a strain rate of 1(T4 per sec. Test temperatures of 77", 200°, and 400°K were attained by immersing the specimens in liquid nitrogen, dry ice-acetone mixtures, and silicone oil, respectively. The critical resolved shear-stress (CRSS) values for silver-base zinc crystals as a function of composition and testing temperature are given in Fig. 1. It will be noted that the CRSS for silver-base zinc solid solutions, as in the silver-base aluminum1 case, depends on temperature in a manner typical of fcc solid solutions: at high temperatures (-300°K and above), the CRSS is relatively temperature-independent but becomes strongly dependent on temperature at lower testing temperatures. A reasonable picture of solid-solution strengthening for silver-rich solutions at room temperature based on "direct" strengthening mechanisms3 is as follows. Since silver alloys have low stacking-fault energies, extended dislocations are expected and it is possible that Suzuki locking4 makes the major contribution to the room-temperature solute strengthening. This provides essentially temperature-independent strengthening since thermal motions of the dislocation line are not large enough to aid the dislocation in escaping the solute atmosphere extending over the fault width. An estimate of the

Jan 1, 1964

By Walter Miller

AFter a year's continued impact of war, the task of the petroleum-refining industry stands out clearly and looms up in larger aspect. This time it is not, as it was so largely in the first World War, simply a matter of increased quantity—more and more of the same petroleum products that had substantially been standard for years. In this era the emphasis is largely on newer and improved materials which had been produced, if at all, in comparatively insignificant quantities, and for which manufacturing equipment was not available on a large scale. At the beginning of 1942 four great product needs (besides a number of lesser ones) confronted the industry: 100-octane aviation gasoline, toluene for T.N.T. production, high-quality lubricating oils for aviation and Army equipment service, and petroleum chemicals for synthetic rubber manufacture. The difficulty in presenting a review of engineering progress in petroleum refining during 1942 is that there is so little one is free to say about so much which has been and is being accomplished. At the opening of 1942 the program was to increase the then existing capacity of 50,000 bbl. a day of aviation gasoline to over 150,000 bbl. daily by building new plants at an estimated installation cost of $150,000,000. Later in the year. after the announcement by President Roosevelt of a large increase in the program for war-plane building, additional contracts were made between the Reconstruction Finance Corporation and rehers to raise the capacity to 250,000 bbl. per day. The greatly increased scope of the war activities in all parts of the world, the obligation of the United States as the arsenal of the United Nations, and the greater importance and use of bomber, transport, and cargo planes will undoubtedly bring about plans and installations for a further increase in production of aviation gasoline over the present announced plan. In this connection, Jesse Jones, Reconstruction Finance Corporation Chairman, announced that as of Oct. 31 the R.F.C. had through its subsidiary Defense Plant Corporation entered into contracts for the construction, expansion, or equipping of 28 plants to increase 100-octane aviation gasoline production, but gave no data on 'capacity involved or completion dates. His list did not, of course, include a number of existing plants, and some installations being made by companies who are themselves financing the construction. Production from existing operating installations was materially increased in a number of instances as a result of pooling knowledge of improvements in operation and also by the exchange of Components going into 100-octane blend to enable greater quantities of aviation gasoline to be produced from the over-

Jan 1, 1943

The Western World's gold reserves now exceed 23,000 mt (750 million oz), 65% of which exist in South Africa. Although several major mines are reducing production or closing because of depletion of reserves, new mines or expansions of existing mines are coming on-stream which will maintain an annual production of 684 mt (22 million oz) of gold well into the 1990s. These new operations by the South African mining industry represent the largest expansion since the opening of the Witwatersrand gold fields in 1886. Included in three new mines being opened is that of Anglo American Corporation's Elandsrand plant, their fir& new gold venture in South Africa in seventeen years. Current average grade of South African mines is 8.2 g Au per mt (0.24 oz per st); and while the cost of the Elandsrand 135,000 mt (149,000 st) operation, including mine development, was about $314 million, it is estimated that the cost of a comparable operation started today and completed in the mid-1980s would be of the order of $480 million. New mines to exploit low-grade ore bodies are, therefore, likely to be few in number, and further expansion will undoubtedly be in the form of extensions to existkg operations where cash flow can be used to finance development. The authors' first monograph, "Gold and Silver Cyanidation Plant Practice," devoted a section to South African cyanide plant operation; and it is believed that this new volume would not be complete without a description of Elandsrand, South Africa's newest gold plant. The Elandsrand mine is adjacent to Anglo American's Western Deep Levels on the Far West Rand. The decision to go ahead with the development was taken in mid-1974 from the results of exploration drilling carried out over a period of .lo years. Results of 17 bore holes and 68 intersections of the Ventersdorp Contact Reef had indicated a gold-.bearing reef less than one meter thick at a depth of 1,800 to 3,000 meters (5,900 to 9,840 ft). Preliminary studies indicated a mine of 900 km (560 miles) of underground workings would yield 725,000 kg (23. 3 million oz) of gold from 60 million mt (66 million st) of ore to be milled over a period of 34 years. Eventually, when the mine is in full production, the total hoisting capacity will be 300,000 mt per month (331,000 st) for a milling capacity of 225,000 mt per month (248,000 st). The Elandsrand surface facilities have been built on a low range of 0 hills to take maximum advantage of the 10 slope in transporting ore

Jan 1, 1981

By E. R. Brownscombe, Francis Collins

The pressure distribution in a reservoir producing an incompressible fluid by radial flow in a horizontal structure is a simple logarithmic function' used daily by reservoir engineers. The assumption of an incompressible liquid is equivalent to assuming that pressure is maintained constant at the well radius and at some external "radius of drainage," or, in other words, that the entire flow into the well passes across the external radius. In most cases a well is surrounded by other wells draining adjoining areas so that the "radius of drainage" is not a line of constant pressure with flow equal to the flow into the well but rather a contour of zero pressure gradient across which no flow occurs, production being due to the expansion of the liquid within the area. The radial flow steady state pressure distribution for this case does not seem to be extensively used despite the fact that the mathematical analysis has been given in detail' and the results are simple and generally applicable. 'The object of this discussion is to develop this result from a physical rather than a mathematical viewpoint, thereby aiding intuition in judging circumstances to which it may be applicable. If the production rate at a well in an unsaturated reservoir is maintained constant while no flow occurs across the outer radius a steady state will soon be reached in which the flow rate or pressure gradient is constant with time at all points in the reservoir. To preserve such a condition it is necessary that the pressure decline at the same rate at all points in the reservoir, that is, the curves of pressure versus radial distance at successive times are all parallel. Then each unit volume of oil is expanding at the same rate and contributing an equal share to the production. The rate of flow q across any circle r is thus proportional to the volume of the reservoir between r and the external radius re, or q = qw (I-r2/r2e) ......(1) where q, is the production from the well and it is assumed that rw is very small compared with re. This equation can be combined with the differential form of Darcy's law for radial flow, 2phkr dp q =—— ........(2) aµß dr ( where q is not a constant as in the incompressible flow case but is a function of r given by Equation (1). If Equation (1) is substituted in Equation (2) the variables p and r can be separated and the result integrated to obtain the pressure distribution p = pw +--------In------------- 2pkh[ rw 2re2] ......(3) This equation differs from the incompressible case only in the addition of the term proportional to the square of the radius

Jan 1, 1950

By G. W. Thompson

G. W. THOMPSON,* Brooklyn, N. Y.-This subject has two aspects, neither of-which can be ignored: these are the economic aspect and the technical aspect. Under ordinary conditions, economic law will take care of the conservation of tin. Under present conditions it seems desirable that economic law should still be permitted to operate as far as is practicable. It is true that this law operates rather slowly, and that under war conditions it cannot be depended upon to give our Government the supply it immediately needs. There should, therefore, be a designation of the essential industries by the Government, and tin should be supplied for those needs, letting the non-essential industries take what is left. At the same time, information ought to be forthcoming as to how tin can be conserved; with tin selling at 80 c. per pound, more or less, it is to the interest of every consumer to get the best information he can as to how he can save tin. Economic law would properly punish those who do not study their own interests in this way. I deprecate, therefore, any centralized socialistic effort toward avoiding penalties through failure to observe and obey economic law. In saying this, however, I am not unmindful that it is desirable for our Government to take such control of the tin situation as may be necessary to the prosecution of the war, practically regardless of the effect of such action upon individual industry, which should studiously seek to adjust itself to the new condition. The Government should promulgate such technical information as it can collect, showing how tin can be conserved, and should urge upon every consumer the exercise of his common sense in self-protection. There is very little danger of any one attempting to hoard or corner tin, in the present state of the market. Most consumers will be glad to live from hand to mouth, covering their sales by purchases, or vice versa. As to the technical aspects: Tin and tin alloys are used to give certain practical and also certain artistic results. The practical factors are those involved in proper adhesion, continuity of surface, protection, the right degree of hardness, proper working qualities, etc. The artistic results are those that appeal purely to the eye or to our cultivated sense of what is desirable. There is no doubt that a great deal of tin could be saved if there were not a demand for certain pleasing effects. How can this saving be brought about? The users of tin hearing alloys are not the only ones involved in this question. The manufacturers of solder and babbitt have for a long time sought to give certain appearances to their fabricated bars and ingots in order to make them more salable. The user of a solder is very apt to judge of its working qualities by the appearance of the bar; the same thing is true with regard to babbitts. Under ordinary conditions, manufacturers are justified in trying to

Jan 12, 1918

By I. Hawke, K. Barron

I. Hawkes (Postgraduate School in Mining, University of Sheffield, Sheffield, England) — The photoelastic stressmeter is proving to be a very practical tool for 'in-situ' measurements in the fields of civil and mining engineering and Barron's article has therefore come at a very opportune time, supplementing as it does, the considerable amount of laboratory and field data which is being accumulated.1,2,3 There are however several points relating the application of Barron's conclusions to the practical use of the meter which require further elucidation. EASE OF READING If the photoelastic stressmeter is to have a wide application, the fringe orders must be easily measured. The system adopted by the writer and his colleagues at Sheffield for the uniaxial stress case is to read the fringe order at the 45 point, 0.20 in. from the center (11/4 in. diam meter). This procedure has been recommended because the fringes not at this point form a very distinct 'eye' which is obvious even to those who have had little experience with photoelastic fringe patterns. Barron points out that this point can also be used up to a stress ratio of 0.33 and in practice this is normally done. In biaxial fields above a ratio of 0.33 the 'eye' is no longer apparent and the fringe order must be ascertained at some other point. The writer and his colleagues experimented at various points and finally chose a point at a distance 0.175 in. (11/4 in. diam meter) on the minor stress axis and fixed this point on the meter by inserting a collar of this diameter. This procedure enables the 'eye' technique to be used for uniaxial stresses as the 'eye' falls outside the collar; any other technique for biaxial patterns would require lines to be engraved on the meter itself and reading difficulties would be experienced by all but the most highly trained. It is interesting to point out that in a great many field applications ranging from underground pillars to building foundation piles the stresses measured have been uniaxial. In such cases, reading the fringe order has been simple even for unskilled persons. SENSITIVITY The photoelastic stressmeter acts as an inclusion, and as such its theoretical behavior is as described by Barron's mathematical analysis. When considering its practical application, however, it must be remembered that rocks and concrete are not mathematically ideal substances. The theory relates the fringe order in the meter to the stresses and the E (Young's Modulus) and the µ (Poisson's Ratio) values of the surrounding material. There is of course no unique E or µ value for rocks or concrete. These values change both with stress level and time load application sometimes to the order of 300%. We at Sheffield have very accurately calibrated the photoelastic stressmeter in a wide range of materials and have also measured the average E values for these materials. The results prove that the meter sensitivity

Jan 1, 1965

By T. A. Klinefelter, O&apos, R. G. Meara, Glenn C. Truesdell, Richard W. Smith

The investigation of domestic talcs was undertaken by the Bureau of Mines, Department of the Interior, in cooperation with the University of Alabama, at the request of the U. S. Army, on Dec. 1, 1941: "Considerable concern has been expressed by the Supply Arms and Service over maintaining continued availability of supplies of the necessary raw materials. These ceramic products are used by the Signal Corps in all army radio equipment, and to a greater degree in the new ultra-high-frequency equipment. The Air Corps has become a user of large amounts of radio-grade ceramics for' aircraft spark-plug covers required for high-altitude operations. In addition, the use of this material is essential to the proper functioning of the radio air-navigation aids of the Civil Aeronautics Board." History The use of steatite and talc in ceramic bodies goes back a great many years. If pure, talcs shrink little under heat-treatment and are very resistant to heat shock. The massive form, commonly called "steatite" by the trade, cuts and works easily, and this was naturally the first method used in obtaining articles of talc. When gas was in general use for illuminating purposes, a. large business was carried on in the manufacture of tips for gas burners.' With the development of uses for electricity, low-tension insulators were made in a similar manner; and, in fact, the forming of shapes from massive talc continues. However, as the business increased, cuttings and waste became more and more of a problem. In the twenties, one of the larger producing firms had a cooperative agreement with the Bureau of Mines at its Columbus station to work out a body using the finely powdered material. Somewhat earlier, manufacturers of spark plugs used the finely ground talc as part of the body and to some extent in wall-tile bodies. Somewhat later it came into use for kiln furniture and similar products and still more recently it has been used in some dinnerwares. With the development of the radio and the high-frequency fields generated, it was found that a dense steatite porcelain was far better than even high-tension electrical porcelain, which is a clay-flint-feldspathic type of body. Until the war increased the demand, the several pioneer steatite-porcelain manufacturers were able to furnish adequate supplies. When war began in Europe and Asia, three important foreign sources of raw material were cut off; i.e., the French, Italian, and Man-churian talcs. Domestic producers of high-grade porcelain are few, and the trade

Jan 1, 1948

By Alfred E. Hunt

The charge to be described was made in a seven-ton furnace, with a hearth twelve feet long and eight feet wide, with three gas and three air ports on each side. The stock of the entire heat was charged cold in one hour and five minutes, a part of the pig being first placed upon the bottom to protect it, then upon it the plate-scrap and blooms, and finally the remainder of the pig—some two thousand pounds. In fire hours and twenty-five minutes after beginning the charge the metal was melted down level, and two hundred pounds of hot twelve-per cent. spiegel was charged, care being taken to have it entirely immersed in the bath. In two hours more the bath was thoroughly melted and hot, and began to boil, i. e., the carbon began to be oxidized and evolved through the bath of covering slag as carbonic acid and carbonic oxide gases. Seventy-five pounds of lumps of Republic specular iron ore were added at this time, increasing the action, so that in ten minutes after the metal was in active ebullition. A test of the metal showed it to have about 0.90 per cent. carbon. One hour after the first ore was added a test was again taken, after thorough rabbling of the metal, and it was found to be 0.37 per cent. carbon. One hundred pounds more of lump Republic ore and about seventy-five pounds of limestone were then added, and fifty minutes later, after the bath was thoroughly rabbled, a -test showed the metal to have 0.23 per cent. carbon. Twenty-five pounds more of Republic iron ore were added and the metal allowed to boil for twenty minutes, when a test, after rabbling, showed the carbon to be 0.18 per cent. and the manganese to be 0.01 per cent.; the slag fracture was vitreous and of a very dark-green color. About forty pounds of limestone were added, and, the metal being hot and in a state of quiet ebullition, a hickory pole of twelve feet length and about four inches diameter, was run through the aperture in the centre door and held in a steady inclined position in the bath, with the end touching the bottom, the pole being shoved in further as it was burned away. The bath was carefully watched to see that the action that ensued was not too violent, the pole being several times

Jan 1, 1884

By T. G. Richardson, F. M. Perkins

In the recent paper of Richardson and Perkins entitled "A Laboratory Investigation of the Effect of Rate on Recovery of Oil by Water Flooding,"' the authors found very little appzrent effect on oil recovery of having free gas saturation present prior to water flooding in unconsolidated sands. We agree that the effect in this particular system was small but do not feel that the data presented should be regarded as disproving work of others which has shown an appreciable effect. The authors do not make such a claim, but neither do they advance an explanation of the difference. In our experience the following factors must be carefully considered when studying the relation between residual oil saturation after water flooding and initial free gas saturation: (1) the magnitude of the inherent residual oil saturation, i.e., the residual oil saturation with no free gas; (2) the increase in oil-water viscosity ratio with pressure lowering if the gas saturation is obtained by solution gas drive; and (3) the oil shrinkage which occurs with pressure lowering and gas evolution. The system studied by Richardson and Perkins gave residual oil saturations as low as 20 per cent without free gas present, and one should perhaps not expect much further lowering. As an illustration of the magnitude of the effect when the residual oil saturation is inherently higher we submit the accompanying figure. These data were obtained on an unconsolidated sand under elevated pressure in a system similar to the one described by Richardson and Perkins. Gas saturation was established by gas drive before water flooding. The viscosity ratio was 600:1 under the conditions of the displacement. Here the gas was extremely effective in reducing residual oil saturation. This fact was also indicated by Kyte, et al.2 Their plots of residual oil saturation vs initial gas saturation show trends of greater free gas effect with higher oil viscosities. The pressure-dependent effects were not discussed by Richardson and Perkins. They should be separated from the free gas effect if the objective of the study is a correlation of residual oil saturation vs initial free gas saturation. The increase in oil viscosity when gas is released from solution tends to increase residual oil saturation. This effect is rather small in the viscosity range of kerosene. A Buckley-Leverett calculation, assuming an increase in viscosity ratio from 1.2 to 1.8, indicates an increase in residual oil saturation of about 1 per cent of pore volume. Thus, one would expect this system, if operated at constant viscosity ratio, to show a slightly greater free gas effect. As Dyes- as shown, oil shrinkage can offset the beneficial effect of free gas on waterflood oil recovery, if the gas saturation is established by depletion. Since

Jan 1, 1958

By H. B. Aaron

DIFFRACTION micrography provides a useful tool for studying complex strain fields. Newkirk1 observed an X-ray diffraction effect due to strain interactions at the intersection of slip lines in LiF and attributed this effect to a reduction of primary extinction due to strain-gradients. It is the object of the current study to correlate the observations and rationalize the appearance of the strain fields around intersecting slip planes in x-ray extinction contrast studies by a semiempirical method. Fig. 1 shows typical strain patterns observed by Newkirk on (200) reflections in LiF using chromium radiation and a variation of the Berg-Barrett (B-B) technique. In other reflections (e.g., {220}) the strain patterns are absent. If one defines a vector 3 along the striations from the more to the less dense portion, and a vector v in the direction of the X-ray beam parallel to the reflecting plane, such that both 3 and v lie in the reflecting plane of the crystal, Fig. 1, then the positions of the striations on (200) reflections appear to be confined such that where is the angle between v and 3, Fig. 1. It will be seen later that 3 is the projection of Sb on the reflecting planes. In some instances the strain effects are observed only above the slip plane, Fig. l(C), in others only below, Fig. l(D). Where the strains appear to be both above and below the slip line, Fig. l(E), one sees that there are actually two slip lines present, Fig. 1(F) and (G). Furthermore, the strain patterns are observed in the vicinity of the intersection of emergent edge dislocations (diagonal lines on the micrograph) with emergent screw dislocations (horizontal lines on the micrograph), e.g., Fig. l(HJ) and (MN), but not in the vicinity of the intersection of two emergent edge dislocation arrays, Fig. l(HJ) and (KL). However, in the latter case the contrast of the dislocation array itself is reduced along (KL) and increased along (HJ). Line (AB) in Fig. 1 is the edge of the crystal, and the material to the left of (AB) is the side of the sample. Any empirical correlation will have to include most, if not all of the aforementioned observations. Lang2 and Newkirk1 determined that the condition for contrast is given by g-b#0 [2] where b is the Burgers' vector and g the diffraction vector (normal to the reflecting planes). If one assumes that the direction of the observed strain fields is given by the vector sum of the slip vectors (Sb1) of the intersecting slip planes, then Eq. [2] may be generalized to g-S#0 [3]

Jan 1, 1963

Jan 1, 1935

By N. S. Stoloff, R. G. Davis

It is concluded from an X-ray stztdy that the formation of the hcp Mg3Cd superlattice is a nuclea-tion and growth reaction. A two-phase, ordered-plus-disordered, region is observed between 153" nnd 141"C. A maximum in the flow stress is observed both at temperature and in quenched specimens within the two-phase region. The peak arises fro112 the extra energy required to create antiphase boundary upon cutting the ordered regions. Hardening during isothermal annealing in Mg3Cd has been shown to be similar to the domain hardening in Cu3Au-type alloys in that up to the maximum the structure is ordered domains growing into a short range ordered matrix. The hardening is due to a combination of short range order strengthening and the strengthening produced when antiphase boundary has to be created. In a recent study1 of the effect of long-range order upon the mechanical properties and deformation modes of hcp Mg3Cd a comparison was made be- tween quenched (disordered) and slow-cooled (fully ordered) specimens. The most striking observations were that the disordered alloy yields at a much higher stress than the ordered alloy, and that there is a change in slip mode from primarily (_0001) ba_sal slip in the disordered state to (0001), {1010}, {1122}, and {l011} slip in the ordered state. The main purpose of the present work is to extend these observations to determine whether MgsCd exhibits a peak in flow stress at an intermediate degree of order, or at a critical domain size, as do other orderedstems. However, disagreement exists about the Mg3Cd order transformation with respect to: 1) the location of the critical temperature for order, 165°C or 153"~,' and 2) how the degree of order varies with temperature. Welber et a1.5 concluded from specific heat measurements that the formation of Mg3Cd is a second-order reaction with the degree of order a continuous function of temperature, while Moore and Raynor concluded that it is neither a first-order reaction, with the degree of order a discontinuous function of temperature, nor a second-order reaction. Consequently it was considered necessary to undertake an X-ray investigation into the change in degree of order and structure in the

Jan 1, 1964

By Walter Miller

AFter a year's continued impact of war, the task of the petroleum-refining industry stands out clearly and looms up in larger aspect. This time it is not, as it was so largely in the first World War, simply a matter of increased quantity—more and more of the same petroleum products that had substantially been standard for years. In this era the emphasis is largely on newer and improved materials which had been produced, if at all, in comparatively insignificant quantities, and for which manufacturing equipment was not available on a large scale. At the beginning of 1942 four great product needs (besides a number of lesser ones) confronted the industry: 100-octane aviation gasoline, toluene for T.N.T. production, high-quality lubricating oils for aviation and Army equipment service, and petroleum chemicals for synthetic rubber manufacture. The difficulty in presenting a review of engineering progress in petroleum refining during 1942 is that there is so little one is free to say about so much which has been and is being accomplished. At the opening of 1942 the program was to increase the then existing capacity of 50,000 bbl. a day of aviation gasoline to over 150,000 bbl. daily by building new plants at an estimated installation cost of $150,000,000. Later in the year. after the announcement by President Roosevelt of a large increase in the program for war-plane building, additional contracts were made between the Reconstruction Finance Corporation and rehers to raise the capacity to 250,000 bbl. per day. The greatly increased scope of the war activities in all parts of the world, the obligation of the United States as the arsenal of the United Nations, and the greater importance and use of bomber, transport, and cargo planes will undoubtedly bring about plans and installations for a further increase in production of aviation gasoline over the present announced plan. In this connection, Jesse Jones, Reconstruction Finance Corporation Chairman, announced that as of Oct. 31 the R.F.C. had through its subsidiary Defense Plant Corporation entered into contracts for the construction, expansion, or equipping of 28 plants to increase 100-octane aviation gasoline production, but gave no data on 'capacity involved or completion dates. His list did not, of course, include a number of existing plants, and some installations being made by companies who are themselves financing the construction. Production from existing operating installations was materially increased in a number of instances as a result of pooling knowledge of improvements in operation and also by the exchange of Components going into 100-octane blend to enable greater quantities of aviation gasoline to be produced from the over-

Jan 1, 1943

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