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By G. S. Ansell, J. Weertman

The creep behavior of an aluminum alloy hardened with a finely dispersed phase of aluminum oxide was investigated. The as-extruded alloy shows an approximate steady-state creep in which the creed rate depends exponentially on the applied stress. The activation energy of creeb is abbroximately 150,000 cal per mole. The recrystallized alloy shows no steady-state creep. ONE method of improving the creep resistance of a metal is to introduce a finely dispersed second phase into the metal matrix. The improvement of the creep resistance has been qualitatively explained by assuming that the dispersed second-phase particles act as obstacles to dislocation motion. If the main effect of second-phase particles is simply to hinder dislocation motion then it is possible to derive a high-temperature creep equation for a dispersion-hardened alloy in a straightforward manner. In the Appendix of this paper such an equation is derived from a creep model which works very well for pure metals. Recently, F. V. Lenel has fabricated, for the first time, powder extrusions of aluminum-aluminum oxide in a large-grained recrystallized form. This alloy, designated as MD 2100, consists of a fine dispersion of aluminum oxide plates in a matrix of commercial purity aluminum. A considerable amount of investigation has been carried out concerning the microstructure and physical properties of this alloy.&apos; ) The aluminum oxide is present in the form of flakes 130A units thick and 0.3 u on edge. They are dispersed in the aluminum matrix with an average spacing of approximately 0.5 jx. The spacing varies in the range of 0.05 to 1.5 µ. The alloy structure is extremely stable at high temperatures. For this reason the alloy offers a unique opportunity for a fundamental study of creep of a very finely dispersed two-phase alloy. Lenel supplied specimens in both the unrecrystallized and recrystallized condition. This paper reports high-temperature creep experiments carried out on these specimens. The results obtained were rather unexpected. No steady-state creep was observed in the recrys-tallized material. In fact, after some transient creep which takes place upon loading, the creep rate is essentially zero ( < 10-8per min). If the second-phase particles acted solely as obstacles to the motion of dislocations, measurable steady-state creep would be expected. Since none is observed it appears that the main effect of the fine dispersion in the recrystallized material is to inactivate the dislocation sources themselves, rather than hinder the motion of dislocation loops created at these sources. EXPERIMENTAL DETAILS Specimens were tested in wire form, 0.087 in. in diam for the as-extruded alloy, and 0.035 in. in diam for the recrystallized alloy. These samples were held in friction-type wire grips; a gage length of 2.5 cm was used for all the creep tests. The specimens were held at 600°C in the test apparatus for at least 15 hr prior to each test. The tests were run under the condition of constant loading and, since the creep strains were small, can be considered as constant stress tests. The temperature of testing was held constant within 3°C. Elongations were measured with an optical cathetometer which was capable of measuring strains as smaIl as 0.00012. This allowed the measurement of strain rates as low as l0-8&apos;per rnin. In addition to the creep tests optical micrographs were made in order to determine both the grain size and microstructure of these materials. RESULTS Fig. 1 shows a few typical creep curves obtained from the as-extruded material. The elongations were somewhat erratic, but each curve shows a region of quasi-steady-state creep from which an approximate steady-state creep rate can be obtained. In general the higher the stress at a given temperature, the greater the total elongation before fracture. The lower the applied stress, the longer is the region where the creep rate is almost constant. Summary data from the creep tests of the as-extruded material are listed in Table I. The steady-state creep data of the as-extruded material for a range of stresses at a constant temperature follow a creep equation of the type creep rate = K&apos; = A exp (&) [11 where A and B are constants, k is Boltzmann&apos;s constant, T is the absolute temperature, and a the stress. The standard error of estimate of the data received is less than one order of magnitude. As shown in Fig. 2, if one compensates the creep-rate data for the effect of temperature over the range of test temperature, the steady-state creep data roughly follow a creep equation of the type Temperature compensated creep rate = K* = A exp

Jan 1, 1960

By C. E. BOCKUSD

WHEN Mr. Bain asked me to lunch with you he requested that I say a few words as to how the Institute could be helpful to the bituminous coal industry. I feel like saying, "Thank you, what have you?" I do not want to trace in detail the story that is old already to many of you. On the other hand it does take some little stage-setting to illustrate what is the matter in the bituminous coal industry, a trouble that must some day be cured. There has been something over a century of bituminous coal production as a real business in this country. True, Joliet and Marquette discovered coal in Illinois in 1673, according to published accounts of their travels, and shortly thereafter Father Hennepin also found Illinois coal in 1689. Coal was mined near Richmond in 1750, and Richmond shipped coal to New York and Philadelphia in 1789. But it was not until 1838 that the production of bituminous coal in this country totaled a yearly output equal to the minimum for one class A mine today, for that was the first year that production exceeded 200,000 tons.

Jan 1, 1930

By Charles E. Heinrichs

IN the last decade one of our oldest and largest non-metallic metallic mineral industries has been the subject of persistent technical research, the results of which are another example of the benefits following the systematic application of scientific principles. The consequent improvement in the technique of phosphate recovery represents the greatest material advance in the industry since the discovery of phosphate in Florida in 1881. Moreover, these successes have stimulated interest and development in numerous other nonmetallic industries. Strange as it may seem, and despite the fact that the phosphate deposits of Giles County, Tennessee, together with those of Polk and Hillsborough Counties, Florida, have yielded more than 50,000,000 long tons in the last twenty years, the mineralogy of phosphates has been given scarcely any space in our technical literature. For many years it was the general consensus that these so-called phosphate rocks represented a physical mixture composed principally of tri-calcium phosphate, together with smaller quantities of calcium carbonate, calcium fluoride, iron phosphate, aluminum phosphate and other less important constituents. More recent investigations, however, led to the conclusion that these phosphates really represent a complex mineral in which calcium, iron, aluminum, phosphorus pentoxide, carbon dioxide, and fluorine all form a definite part of the molecule. Colony, after a careful study, utilizing chemical, microscopic, and X-ray diffraction methods, reported that American phosphates consist principally of calcium-carbono-phosphate of the staffalite type.

Jan 1, 1933

By Axel Sahlin

Jan 1, 1898

By JOHN JERMAIN

In my opinion, the explanation of the fuel-requirements involving the conception of heat available and necessary above a critical temperature, as advanced by Johnson 1 and elaborated by Howe, Raymond and others,2 affords a theoretically correct basis for such an accounting. It is the purpose of this paper to set forth a first crude attempt to construct a formula which shall show quantitatively the relation between the various factors affecting fuel-economy, and afford a means of comparing the enormous amount of data on the fuel-consumption of various blast-furnaces, at various times and under various conditions of operation. I have also applied this formula to a large number. of individual cases, and have, by its means, compared the furnace-practice of several important iron-making districts. II. DERIVATION OF FORMULA FOR FUEL-REQUIREMENTS. The general expression for the fuel-requirements of the blast-furnace, which I believe to be theoretically correct as to form, is as follows Carbon per ton of iron = Heat per ton of iron necessary in hearth above Tc./Heat per pound of carbon available in hearth above Tc. XFactor of rate of driving. +Carbon dissolved by CO2 of flux. +Carbon dissolved incidental to reduction of ore. + Carbon dissolved in pig-iron. (NOTE.-Tc = critical temperature.) Since, according to Johnson&apos;s theory, fuel-economy is usually limited by heat available and necessary in the hearth, rather than by the total heat supplied and necessary, we may write Carbon needed in hearth = Hn/Ha in which Hn is the heat per ton of iron necessary in the hearth above some critical temperature, and Ha is the heat per pound of carbon available in the hearth above this same critical tem¬perature. 1 Trans., xxxvi., 454 (1906). 2 Trans, xxxvi., 792 to 798 (1906) ; Trans, xxxvii., 216 to 237 (1907).

May 1, 1911

By R. L. Dietrich

Magnesium alloy sheet has less ability to accept bending at room temperature than most of the heavier metals. In work designed to improve the bend properties, the preferred orientation of the sheet is of major importance as it is in all studies of the properties of wrought magnesium products. When rolled into sheet, all of the common magnesium alloys form an orientation texture having the basal (002) planes approaching parallel to the surface of the sheet. This texture is only slightly affected by annealing. Magnesium single crystals are highly anisotropic, and, as might be expected, so are magnesium alloy wrought products in which a strong preferred orientation is developed. It is therefore not surprising that bend properties are affected by orientation. Ansel and Betterton1 reported that the orientation of AZ3lXt sheet varies from surface to center and that bend properties are improved by etching away the sharply oriented material at the surface of the sheet to reach the more broadly oriented structure below. This paper covers a study of that orientation, either during the rolling process or by treatment of the finished sheet, in an effort to improve the bend properties and toughness of sheet. Literature The orientation texture of magnesium and magnesium alloy sheet has been studied extensively. Early determinations2 showed that pure magnesium sheet has a preferred orientation in which the basal planes are parallel to the sheet surface within very narrow limits. J. C. hIcDonald3 and J. D. Hanawalt4 reported that sheet containing a small amount of calcium develops a "double" texture, that is, the majority of the basal planes are a few degrees from parallel to the surface and there is a noticeable vacancy at the parallel position. Bakarian5 made careful quantitative pole figures of both pure magnesium sheet and MI alloy SEPTEMBER 1949 sheet which show these features. In all of these studies, however, the orientation was determined by transmission methods in which the resulting pattern is an average through the thickness of the sheet. The tendency of wrought metal to exhibit a different orientation at the surface from that in the center has been reported by many investigators. G. von Vargha and G. Wasserman6 found that with copper, aluminum, iron, and brass the textures of rolled compared to drawn wires were the same at the center but differed markedly at the surface. It was also reported by investigators7 that the orientation of rolled aluminum varies from surface to center. Har-greaves8 found that the surface texture of AM503 (magnesium alloy similar to MI) sheet was different from the center texture. It is reported by Edmunds and Fuller9 that zinc alloy sheet sometimes had a thin layer at the surface with a strong orientation of the basal planes parallel to the surface, which, if present, impaired the bend properties of the sheet. Part1 Surface Orientation ofMag- nesium Alloy Sheet and the Effect on Properties Attempts to correlate the bend properties of magnesium alloy sheet with tension ductility over short gauge lengths proved unsuccessful and the subsequent investigation showed that nonuniformity in orientation is a con- tributing factor as the properties of the surface material have a much more important effect in bending than in tension. A program to study the relationship between surface orientation at the surface and bend properties was then undertaken. First, the effect of etching away the surface of sheet on the bend properties and the orientations at the various depths were studied. Sheet samples of M1, AZ31X, and AZ61X were etched in dilute nitric acid to remove the surface material for various depths to 0.015 in. As may be seen in Table 1, the minimum bend radius improved considerably as the surface layers were etched away but it was necessary to etch the sheet quite deeply, much more so than was found necessary by Edmunds and Fuller9 on zinc sheet. It is also apparent that the amount of etching required is a function of the sheet thickness. In all of this work, radii were measured as R/t, the radius divided by the sheet thickness, in order to eliminate the effect of the reduction in sheet thickness produced by the etching. To determine the orientation texture of the sheet, X ray reflection patterns were taken using copper radiation with the bearn striking the specimen at an angle of 17&apos; to the surface, which is the Bragg angle for the (002) planes of magnesium. Two exposures were made of each specimen, one with the beam perpendicular to the rolling direction and the other with the beam parallel to the rolling direction. The symmetry of the preferred orientation in magnesium sheet is such that these two photographs gave an approximation of the pole figure sufficiently accurate for qualitative work and it was not thought worthwhile to make complete pole figures. These X ray patterns show that the orientation has a much narrower spread at the original surface of the sheet than below the surface. The narrow spread is found in sheet having the majority of the basal planes (002) parallel to the surface, and since this is an unfavorable position for slip, it is

Jan 1, 1950

By Donald McLaughlin

INCREASING variety of interests among mining geologists is becoming more and more marked, as the frontier of their science and of its applications continues to expand. Each of the traditional lines of inquiry provides its crop of new and better defined problems, and answers to them are being found in far more precise terms than in the past as older uncertainties .are swept away with the sharper techniques and the even sharper ideas of modern geology. A glance over the assemblage of projects and publications in 1939 reveals conspicuous activity in many different parts of the front, such as the attack on the controversial question of the acid or alkaline character of ore-forming solutions, the place of mineral districts in the larger structural framework of continents, and the place of ore shoots in the local patterns of districts. Instructive comparisons are being made which cut across lines of older correlations or which reinforce them by pointing out heretofore ne-

Jan 1, 1940

By G. M. Gay, R. L. Perrine

This paper describes a method of numerical computation for three-dimensional, unstable, miscible displacement behavior useful for heterogeneous systems, as well as for more ideal conditions. In the method, flow equations are first linearized by a perturbation approach. The basic flow process is separated and a solution for its behavior readily obtained. The remaining problem of deviations from the basic flow caused by non-ideal conditions is then subjected to numerical analysis. Results obtained from use of the method are also presented. Although conditions assumed in the test cal-culations were severe, results show the type of dispersing flow expected and appear quite satisfactory. The method has eliminated or reduced in importance problems of oscillating values near steep fronts, excessive computer smoothing, etc. A unique advantage of the method is that the source of variations from ideal behavior can be observed. ,The one serious drawback results from the algebraic complexity of the perturbation approach, and the need for second-order terms to be retained in calculations of interest. Fewer array points are available and more computer time is required than would be desired. However, these difficulties are also experienced with other approaches to the solution of three-dimensional dispIacement problems. INTRODUCTION Prediction of behavior of the miscible displacement process within a porous medium for any system of engineering importance is plagued by a number of difficulties. With typical fluid properties the displacing fluid has the lower viscosity, and there is a natural tendency toward flow instability. The problem of predicting instability is compounded by the fact that every real system is heterogeneous. Permeability will vary from point to point — not entirely systematically, and yet not in a random fashion leading to a readily defined average. Furthermore, permeability is unlikely to be isotropic. These permeability properties, which are characteristic of any real porous medium, accentuate the effects of flow instability. Another factor to be considered is that flow dispersion accompanies the displacement process in a porous medium. Mechanistically, dispersion is due to the fact that flow between any two points in the medium follows multiple tortuous paths, each characterized by slightly different flow properties. The fact that the coefficient characterizing dispersive properties of the real medium JS a tensor with variable elements complicates matters. Further difficulties arise because the parabolic influence, while not negligible, is small. Thus, there is a tendency toward steep and uneven displacement fronts along which dispersion smoothing must be represented accurately. Yet frequently used numerical analysis schemes may tend toward either instability, oscillation or excessive smoothing, none of which gives the desired accurate picture of flow behavior. Thus, while many experimental and analytical studies of the process have been made, predictions of actual performance are still subject to considerable uncertainty and possible improvement. This paper reports on part of a study which attempts to develop improved methods for solution of the flow equations describing the miscible displacement process. Of necessity, the calculations were performed on a large digital computer. A three-dimensional system is represented, and the coefficients defining dispersion and permeability can be varied in a manner representative of a real system. Because the differential equations are nonlinear, a first step is to linearize them using a perturbation approach. Objective of this approach has been to separate the basic flow which would occur in an ideal system and for which predictions are readily made. Then the numerical analysis, which is necessarily complex, is directed toward solution of the perturbation equations. These equations state how the basic flow is modified

Jan 1, 1967

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 Kenneth S. Ritchie

TOO often, many foremen; superintendents, managers, and executives, "The Bosses" of the oil and mining industries, do not fully realize: (1) How much personal actions &apos;.on the job" may reduce their effectiveness in getting work done; and, (2) The importance of harmonious relations with their fellow men. Today. these qualities of personality in the people entrusted with the positions of responsibility are more important than ever with the shortages of labor so critical in vital war production. Likewise, many engineers do not fully realize that their work is essentially executive in character; i.e., other people do the actual labor. Without their help. the engineer&apos;s work would not be done. A clearer appreciation of this fact would increase their interest: (1) in the nontechnical aspects of their work. and, (2)in their relations with others, particularly the individuals in their own organization. Consequently, these engineers would be more successful in equipping themselves for greater responsibilities and increased remuneration.

Jan 1, 1944

By P. D. I. Honeyman

DURING 1938 many copper companies again felt the economic pinch and smelter operations were often on a reduced basis which some- times resulted in intermittent operations and complete shutdowns. During the last half of the year production was stepped up and smelting operations resumed a more normal appearance. One of the present-day trends in reverberatory sme1ting is definitely toward high-tonnage operations. i\ t the Phelps Dodge Corporation&apos;s Douglas plant, the reconstructed 107 by 26- ft. reverberatory furnaces are operated at the rate of 1000 tons of solid charge per day. The arch, all of silica brick; is sufficiently high above the bath to give

Jan 1, 1939

By Alfred E. Hunt

The late Alexander Holley said, on returning from a careful study of the relative merits of the Bessemer and the open-hearth processes, as shown in the best European practice, that, in this country, the open-hearth process would live to attend the funeral of the Bessemer ; and he said this several years ago, when in this country the Bessemer plant and practice had been developed to far outstrip that abroad, and when, proportionately, it had reached an advancement much beyond the improvements in open-hearth plants and practice. At the same time, the prevailing idea in the metallurgical world, a few years ago, seemed to be in favor of the substitution of Bessemer for open-hearth steel for most of the higher qualities, and Bessemer enthusiasts loudly proclaimed, that as good steel for all purposes could be obtained by their favorite process as by the open-hearth. It was, in fact, confidently prophesied that very soon tool-steel and similar grades, which consumers had learned to specify, in ordering, to be made by the crucible process, would by common consent be made by the Bessemer, as best adapted to give the desired results. But these expectations have failed to materialize; not only do the crucible people keep on in the even tenor of their way and talk with pride of their comparatively large outputs of " hundreds " of tons per month, as usual, but the open-hearth people have kept fast hold of their original domain of nearly the entire amount of sheared plates, of locomotive tires, of large forgings, spring-steel, agricultural steel, steel castings and the like. Further, owing largely to one of the great advantages of the Bessemer process, which is also one of its inherent dangers, namely, its large output, it has also fallen into considerable disrepute for structural purposes. Not a few experienced engineers are now stipulating in their specifications that Bessemer steel will not be allowed to be used, especially for tension-members.

Jan 1, 1888

By Franklin G. Pardee

WARTIME depletion of the reserves of iron ore in the Lake Superior region of the grade and character now being shipped down the Lakes was serious. The time has come to take stock of the resources that remain in order to plan our future program of supply for our blast furnaces and protect, as far as possible. the tremendous investment made in the Lake Superior iron mining industry. Hugh M. Roberts and William H. Crago have estimated the reserves of the Lake Superior region in the United States at two billion long tons. These reserve figures are of direct-shipping ore and those concentrates produced by methods now in commercial use or those methods that may be expected in the near future. In their estimate they have assigned 392 million long tons to the Michigan ranges (all reserves in long tons) : 112 million tons for the Gogebic. 140 million tons for the Menominee, and 140 million tons for the Marquette.

Jan 1, 1948

By Alexander Anderson

TABLES showing the drift and inclination of wells surveyed in the years 1924 to 28&apos; and in the year 1929&apos; have already been published. Each of these tables included a little over 1,000,000 ft. of rotary hole. In the year 1930 the table -shown-in . Fig. 1, comprising, the results of surveys .of 1,030,344 ft. of hole and representing 11,642 individual survey readings, was compiled. For that purpose we selected &apos;I only wells that had been drilled in California during that year. The footage of Fig. 1 differs from the two earlier tables in that the wells were all drilled in the year 1930. In the earlier tables, the footage shown was surveyed in the years designated, but some of the wells were drilled in earlier years.

Jan 1, 1931

By R. F. Krueger, L. C. Vogel, P. W. Fischer

Previous studies have shown that the permeabilities of sandstone cores are markedly reduced following exposure to drilling fluid and subsequent clean-up with oil at high-pressure gradients. Laboratory experiments reported in this paper indicate that permeability damage from drilling mud or water can be substantially avoided through use of an initial low-pressure gradient followed by gradually increasing gradients during clean-up by reverse oil flow. On the other hand, attempts to improve the permeability of damaged Berea and oil formation cores with high-rate oil backflush (simulated well stimulation) and low-rate clean-up gave erratic results. Essentfully complete permeability repair was achieved in most of the fresh water-damaged cores from Miocene and Pliocene oil-producing formations; only minor improvement was noted generally in tests with both water-and mud-damaged Berea sandstone. Field well stimulation treatments using high-rate back-flush resulted in long-term productivity improvement when production was brought in at gradually increasing production rates and then restricted to a steady value less than the maximum possible rate. Wellbore plugging at high production rates correlated with increasing solids content in the produced oil. Observations and results from these tests agree with current concepts that formation damage in water-sensitive rocks results from movement and bridging of formation fines, rather than from clay swelling alone. INTRODUCTION Many laboratory studies1-g have shown that the permeabilities of sandstone cores are often markedly reduced following exposure to fresh water or water-base drilling mud filtrate. However, work with cores in the restored state has demonstrated that, although permeabilities to water may be very low for sandstones containing hy-dratable clays, flow of oil can often restore a substantial portion of the effective permeabilities to oi1.Neverthe- less, water invasion into water-sensitive sandstone cores results in varying degrees of permanent reduction in permeability to oil.24&apos; Based on field data, Wade&apos;s statistical study" of well completion effectiveness also indicated a correlation between productivity damage and water invasion during completion. Similar damage can result from fluid invasion during workover. Nowak and Krueger&apos; and Bertness4 observed in their early work (1951-53) that formation damage in water-sensitive sandstones was associated not only with swelling of expandable clays but also with movement of dispersed particles. Subsequent work by Monaghan et al." (1959), Atwood&apos;&apos; (19641, Mungan" (1965) and Gray and Rex&apos;" (1965) has led to general acceptance of the hypothesis that permeability damage in water-sensitive formations is caused by migration of finely dispersed minerals and bridging in "brush heap" arrangements at pore constructions. In laboratory studies, Monaghan et al.&apos; found the use of chemicals to be of only minor value for repairing formation damage. Atwood? however, was successful in substantially repairing damage in a number of low-permeability cores using an n-hexanol flush. In the field, except for treatments with acids, the use of chemical washes to reduce wellbore damage has had limited and sporadic success and generally is unpredictable. A statistical analysis of stimulation treatments in silt-blocked wells has shown that physical manipulation of wash materials is more important than chemical composition." The recent work reported on formation damage in water-sensitive sands brings to mind the results of some unpublished exploratory work done in 1954 in connection with drilling fluid studies.&apos; This laboratory work and subsequent field stimulation treatments indicated a beneficial effect of controlled pressure drawdown and the associated production rate on formation clean-up. This paper reports the results of this work and more recent supplemental experiments on the clean-up of water-sensitive sandstones damaged by water or filtrate invasion. PERMEABILITY RECOVERY AFTER DAMAGE BY DRILLING MUD APPARATUS AND TEST SAMPLES A drilling mud circulating system was used to expose cores to simulated wellbore conditions. The mud flow system is the same as that described by Krueger and Voge17 except that no provision was made for scraping

By Victor O. Strobel

Fire-brick hot-blast stoves have been the subject of frequent discussions at the meetings of the Institute; and although it is my object to elucidate some of the points in connection with this subject, I will not go into the specific features of all types, but more especially call attention to a new type recently designed by Mr. Fred. W. Gordon. As the economical production of a ton of pig-iron is a more essential feature than a large output, much depends, where fuel cannot be obtained cheaply, upon suitable apparatus whereby high temperatures can be maintained. Where iron-pipe stoves have been employed, the fuel-consumption reached one and a half pounds of fuel, and, when a larger output was desired, often two pounds, to the pound of iron produced. The temperature attained rarely exceeded 900&apos; F., and that at the expense of frequent renewals of the pipes, which was not inconsiderable. The fire-brick hot-blast stoves of the past five or six years have clearly demonstrated their superiority over the old system. Of the accompanying drawings, Fig. 3 illustrates a four-pass regen-

Jan 1, 1886

By John D. Sullivan

ALUMINUM and magnesium plants in the United States underwent enormous wartime expansion which made many wonder if ghost plants would result when industry swung back to a peacetime basis. Production capacity of primary aluminum ingots was stepped up from 150,000 tons annually to about 1,150,000 tons; magnesium production increased from 2500 tons in 1936 to nearly 200,000 in 1943, with a production capacity of some 300,000 tons. Not only was primary metal production enlarged but also the capacity of prime fabrications such as castings, forgings, extrusions, and sheets was correspondingly increased. In mid-December it was estimated that production of primary aluminum ingots in the United States in 1946 will be about 410,000 tons while consumption will be about 500,000, close to half of the wartime consumption. The 1946 estimated consumption of secondary aluminum is 200,000 tons. The critical shortage of soda ash is hindering production of primary metal, and the outlook for an early relief of this shortage is dark.

Jan 1, 1947

F. E. Bachman, Port Henry, N. T. (communication to the Secretary*):—In discussing Mr. o.o.Laudig&apos;s paper, the Action of Blast-Furnace Gases Upon Various Iron-Ores,&apos; I took the ground that Mesabi-ore explosions were entirely mechanical; but more observation and later experience has caused me to

Jan 1, 1905

By O. E. Palasvirta

Close examination of most so-called new processes in mineral dressing reveals that they were conceived and developed a long time ago. High-intensity magnetic separation is no exception. Although its application in iron ore beneficiation seems new, in Germany the process has been commercially successful for almost two decades. High-intensity separators have long been standard equipment in the glass sand industry; they have also been used in concentrating some of the more unusual paramagnetic minerals. The basic features of an induced-rotor, high-intensity magnetic separator were described by Désiré Korda in Paris in 1905,1 and many patents have since been issued for improvements on the original design. Fig. 1 shows the basic design of an induced-rotor separator. Several U. S. manufacturers have been supplying induced-rotor separators for many years, but these are all devices of relatively low capacity, not suitable for treating such low-cost commodities as iron ore. On the other hand, two German manufacturers are offering induced-rotor separators of high capacity, both proven in the field.

Jan 12, 1959

By H. H. Waller, C. H. Brehaut

At the Jeffrey mine of Canadian Johns-Manville Co. in Asbestos, Que., automatic batched concrete from surface is placed underground pneumatically for distances of 2500 ft directly into forms or to a second placer for greater distances, through 6-in. pipe of high carbon steel. The use of Celite C-4-C in addition to the usual aggregates achieves greater compressive strengths, lowers cost, reduces segregation, and improves workability and placeability results. Each year 25,000 cu yd of concrete are placed without interrupting production and development work in the mine, making possible a cheaper concrete that can be poured wherever and whenever it is needed. In about 90 pct of the underground openings in the Jeffrey mine concrete is necessary to preserve them in their original sizes and shapes for production. In the remaining 5 pct, the greater portion is united with or without steel support. When large quantities of concrete were forecast for underground use at the Jeffrey mine, preliminary and first hand information regarding pneumatic placing was acquired from articles by Bernhardt and Swanson and visits to their respective mines.

Apr 1, 1956