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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' 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 Bernt Ellingsaeter, Terkel Rosenqvist

IN the silicothermic reduction of magnesia, burned dolomite is treated with high grade ferrosilicon in an evacuated steel retort at temperatures between 1150° and 1200°C. The following reaction is assumed to occur MgO + CaO + 1/2 Si (Fe) - Mg(g) +- & Ca,SiO, + Fe with the equilibrium constant on the basis of thermodynamic data for the substances involved and assuming unit activity for all solid constituents, Kubaschewski and Evans' calculated the magnesium pressure as a function of temperature logp,, (mmHg) = 15.06-1.61 T- log T- 13,16O/T. Pidgeon and King," who measured the magnesium pressure by means of a flow method, found values about three times the calculated ones. This may be caused by uncertainties in the thermodynamic data, but may also be caused by the formation of other reaction products, such as Ca,SiO,, which is known to be the stable silicate in equilibrium with lime. Whatever the exact reaction may be, it is evident that as long as all other factors are maintained constant the magnesium pressure will vary with the silicon activity, viz: p,, = &,. (p,,) ", where (p,,)" is the magnesium pressure by the reduction with silicon of unit activity. In the present investigation, p,,, was therefore measured for various grades of ferrosilicon and their silicon activities were calculated. The experimental method was similar to that used by Pidgeon and King. Briquettes of burned dolomite and Fe-Si alloys were placed in a 1 in. heat resistant steel tube and were heated to 1200°C. By means of a flow of purified hydrogen, the magnesium vapor was swept into a condenser filled with steel wool. From the amounts of hydrogen used and magnesium condensed the magnesium partial pressure was calculated. First a tube of 28 pct Cr steel, and later a tube of Kanthal D (a ferrous alloy with 22.6 pct Cr, 2 pct Co, and 4.5 pct Al), was used as a heat resistant tube. The latter tube showed the best heat resistance. The dolomite used had the following composition: 43.6 pct MgO, 55.5 pct CaO, 0.2 pct K,O + NalO, 0.2 pct Fe,O,, and 0.3 pct insoluble. The ferrosilicons were prepared from 98 pct Si of technical grade (0.7 pct Al, 0.3 pct Ca, and 1 pct Fe) by melting with various amounts of electrolytic iron of high purity. The alloys thus obtained were analyzed on their iron and silicon contents, which added up to between 99 and 100 pct. The amounts of reactants were chosen so that there would always be an excess of the oxides, and the average decrease in silicon content during the experiments would be about 1 pct. Most of the reaction occurred in the part of the reaction mixture facing the gas flow. The change in the silicon concentration in the part facing the condenser was, therefore, negligible. To facilitate the reaction, about 1 pct fluorspar was added to the briquette mixture. Fluorspar does not enter the reaction, but is known to act as a

Jan 1, 1957

By Winston W. Spencer

ALTHOUGH by far the largest A consumer of platinum metals in the world, the United States until recently has been in- significant as a producer. Writing in the "Minerals Yearbook" for 1939, H. W. Davis states that 1938 probably marked the beginning of an- other period of transition in the world production of the platinum metals. In that year, he says, their production in the United States jumped to 49,380 oz., or fourth in the rank of world output. In the ten-year period 1925 to 1934 United States output ,averaged only 8300 oz. Practically all of this sudden in- crease in production is attributable to the introduction of mechanized equipment at the placer deposits in the Goodnews Bay district of Alaska. This district adjoins the Bering Sea and Kuskokwim Bay (accented on the first syllable), and is approximately 120 miles south of the mouth of the Kuskokwim River. The nearest village and post office is Platinum, which lies about eleven miles north- east of the Goodnews Bay Mining Company's camp. A good gravel road connects the mine camp and the village.

Jan 1, 1940

D EC. 20-The spirit of Christmas and good will toward men has managed a few brief appearances on the front pages, welcome relief from man's usual ill-will toward man. A couple politicos did their best to brighten the scene by well-publicized romances. There was a general exodus to Florida to patch up nervous systems, and even the UNO quieted down as Mr. Vyshinsky departed for home via Eastern Germany. Before going he opened up a preliminary bombardment for the worldwide "communist peace offensive," and it is now the duty of the 600 million (according to the Cominform) ideological converts to press home the attack. In Washington, Mr. Lilienthal resigned as Chairman of the Atomic Energy Commission and demonstrated again the difficulty of government to retain the services of capable men. The President has yet to appoint another victim- possibly someone nicely noncontroversial and timid. So might the critics be appeased, but it would bode ill for the rapid exploitation of peaceful uses of atomic energy, the relaxation of excessive secrecy, wider sharing of developmental work with friendly nations and possible revision of the Acheson-Lilienthal proposals for inter- national control of the atomic bomb.

Jan 1, 1950

By AIME AIME

AT FOUR O'CLOCK members gathered in the auditorium for the annual business meeting of the Institute which, according to its charter, must be held on the third Tuesday of February each year. President Turner presided and after the usual formal action on minutes announced that he would create a precedent by transferring the President's annual address (which by tradition has always been delivered at the banquet on Wednesday evening) to the business meeting, and, furthermore, would only present a brief abstract of it. Since it appears in full on pages 127-131 of this issue it can be followed with the careful attention its thoughtful analysis of current conditions deserves.

Jan 1, 1933

THE following nominations for officers in the, Petroleum Division have been made by the nominating committee, of which Alfred G. Heggem was chairman: Chairman, John M. Lovejoy, Vice-pres., Amerada Petroleum Co., Tulsa, Okla.; vice-chairman for Refinery Engineering, Walter Miller, Vice-pres., Marland Refining Co., Ponca City, Okla.; vice-chairman for Production En-gineering, M. E. Lombardi, Vice-pres., Pacific Oil Co., San Francisco, Cal.; associate vice-chairmen for Produc-tion Engineering, T. E. Swigart, Prod. Engr., Shell Co. of Cal., Los Angeles, Cal.; Joseph B. Umpleby, Vice-pres., Goldelline Oil Corp., Oklahoma City, Okla.; vice-chairman for Production, W. E. Wrather, Cons. Geol., Dallas, Texas; associate vice-chairman for Production, Joseph Jensen, Associated Oil Co., Los Angeles, Cal.; vice-chairman for Transportation Engineering, E. P. Bly, Engr., Pipe Line Dept., Standard of California, San Francisco, Cal..; vice-chairman for Economics., Joseph E. Pogue, Cons. Geol., New York City. The election will take place, at the annual meeting of the Division in New York in February. Any independent nominations received before Jan. 20 and endorsed by ten members, will be announced in MINING AND METALLURGY for February and placed before the meeting for considera-tion. Extensive plans are being made for the meeting and a large number of excellent technical papers have already been received.

Jan 1, 1927

By P. H. Royster

On the Continent, ferromanganese has been produced in the blast furnace almost continuously since 1876, but little definite information concerning the practice is to be found in technical literature, and almost nothing in the way of a theory of the manganese furnace. In this country, prior to 1904, but one company had attempted its production in a serious way, and none of the operating data or other information from this company has been, or is, available to the public..In the last 5 years, as a result of the restriction of imports, a number of furnaces have been blown in on this alloy, with the result that in 1918 as many as 18 furnaces were in blast. The majority of the men in charge of these furnaces had had little previous experience in such operations; so the Bureau of Mines, in the summer of 1918, undertook the collection of data from ferromanganese furnaces. Operating data were collected by the Bureau from eleven ferromangahese furnaces, which will be referred to throughout this paper as furnaces A, B, C, F, G, I, J, K, L, M, and P; the dimensions of seven of the furnaces are given in Table 1. The companies from whom this information was obtained, and to whom should go the credit for whatever value this information may possess, are the Bethlehem Steel CO.,

Jan 1, 1920

Taking advantage of the lessons in administrative organizations which were taught by the war, Director Van H. Manning has put into effect a new form of organization in the Bureau of Mines. The Bureau is divided into two branches, one the investigations branch and the other the operations branch. F. G. Cottrell, who has been chief metallurgist of the Bureau, has been promoted to the position of assistant director and will be in charge of the investigations branch. F. J. Bailey, who has been chief clerk of the Bureau, has been placed in charge of the operations branch with the title of, assistant to the director. All research and technical control will be exercised through the investigations branch, while the non-technical work, administrative duties, and dissemination of the results of the Bureau's activities will be handled by the operations branch. Under the investigations branch comes the division of mineral technology, in charge of Dr. C. E. Parsons; the division of fuels, under the chief mechanical engineer, 0. P. Hood; the division of mining, under the direction of George S. Rice, the chief mining engineer; the division of petroleum and natural gas, under the direction of J. 0. Lewis, the chief petroleum technologist; and the division of experiment stations, under the direction of D. A. Lyon.

Jan 9, 1919

(The following list contains the names of those members of the Institute of whose connection with military service we have only recently become acquainted; it also includes the names of a few who have recently been promoted or transferred, indicated by a *. A complete list was published in the Year Book, issued as a supplement of the Bulletin for March, 1918.) ANDERSON, AMIL A., Co. A, 309th Regiment Engineers, 84th Div., American E. F., Care Postmaster, New York. ARMSTRONG, HAROLD K., Pilot, Naval Aviation, U. S. Naval Air Station, Miami, Fla. BASSETT, ARTHUR F., Co. 6, -E. 0. T. S., Camp Humphreys, Va. BEDDALL, THOMAS H., Adjutant, 1st Battalion, 1st Gas Regiment, American E. F. BERNARD, CLINTON P., Candidate, 12th Observation Battery, F. A. C. 0. T. S., Camp Taylor, Ky. BROOKE, LIONEL, 50th Co., 13th Battalion, 5th Replacement Engineers, Camp Gordon, Ga. BROWNING, EDWARD, Corp., 1st Regiment Engineers, Co. D, American E. F. BUGBEE, EDWARD E., S. A. T. C. Headquarters, Raleigh N. C. BUTTERFIELD, G. BRUCE, CO. C, 605th Engineers, American E. F. CADOT, J. J., 1st Lieut., U. S. Air Service, American E. F., Care Post- master, New York. CARLOCK, J. B., Major, 2d Battalion, 1st Gas Regiment, American E. F., France.

Jan 12, 1918

By James F. Kemp

In earlier gears, the custom prevailed of regarding the anthracite basins as cases of folding with slight development of faulting. Folding is so pronounced and, in the eastern and western Middle Fields, at times so violent, that the inference was a natural one and led to the widespread impression that practically all the disturbances of the seams could be explained in this way. The cross-sections and maps prepared forty or more years ago for the Second Geological Survey of P ennsylvania, by Mr. Ashburner under Prof. J. P. Lesley, exhibit little else than folds.' So far as I can discover faults fail in the charts, except in one small case in the Henry colliery near Plainsville on the outskirts of Wilkes-Barre. Some years ago, while spending a day or two in Wilkes-Barr, under the guidance of R. V. Norris, I looked over some recent and accurate cross-sections of a numbcr of the large collieries and was deeply impressed with the peculiar behavior of some of the seams and the intervening shales. Thus, a seam might present a small, more or less overturned fold, rising 30 to 50 ft. (9 to 15m.) above its general course, and yet the movement would be taken up in the overlying shales, so as hardly to be noticeable in the seams next above or below. These and similar anomalies, especially when shown with the accuracy of engineer's surveys, possess great scientific and practical interest, bearing as they do, not alone on coal mining, but on theoretical geology and the actual behavior of strata under great compressive stresses. In preparation for the semicentennial meeting of the Institute, an effort was therefore made to secure some of the most interesting sections for presentation to the members. The collection of illustrations here shown is mainly due to Douglas Bunting of the local committee, to whom and to the contributing companies acknowledgments are due. The illustrations are taken from all four of the main basins, but are chiefly from the portions nearest Wilkes-Barre. The first are in the

Jan 1, 1922

By David J. Mack

A survey and critical appraisal of published information about Young's modulus was originally made by the writer because of a complete lack of information about this very important quantity in works on. mechanics, physical metallurgy, physics, and other sciences. It was felt that a comprehensive summary of such information about Young's modulus might be of general interest and may suggest new problems or lines of attack on other problems that involve E. Hence this paper has been prepared even though it is only a review, with no new ideas or experimental data. The references are only those used in assembling the paper. No attempt was made to compile a complete bibliography on the subject of Young's modulus. CalculatioX oP YouNg's Modulus from Theoretical or Empirical CoNsidera-tions Many attempts have been made to compute E from theoretical considerations. The earliest calculations were probably those of Tomlenson (1883) and Souther-land (1891), but Fess'enden4',~ made extensive calculations a few years later and arrived at the relationship: £ = 78.TOw(i)* where V is the atomic volume. In 1923, Peczalski, working from the same standpoint but with more information available on atomic structure, arrived at an identical relationship, which he expressed as: where B is a constant of value about 8 . 107, p is density and mis atomic weight; the atomic volume, of course, being ml p. Portevind4 immediately pointcd out that while the equations of Fessenden and Peczalski were true of the common metals, they gave low values for the refractory metals with high moduli (Fig. I). He showed (Fig. 2) that much better concordance was obtained by means of an empirical equation of the form: F- KT" where K is a constant; T the absolute melting point; V, atomic volume, and a and b constants of value approximately I and 2 respectively. This constant K in the Portevin equation is not necessarily the same for all elements, as shown by Thompson. Other equations for E based upon theoretical considerations have been derived by Honda and Yamada49 and Lasareff.50 The most recent calculations of elastic moduli based upon quantum mechanics are probably those of Fuchs He extended the method of Wigner and Seitz for calculating the lattice energy and compressibility of monovalent metals and computed the elastic constants of lithium, 18

Jan 1, 1946

By Don H. Baker

THE need for new or improved refractory materials has caused metal phosphides to be given renewed scrutiny. Some metal phosphides show high-temperature inertness, are exceptionally hard, and exhibit a marked resistance to chemical attack. Various metal phosphides have been prepared for study by direct combination of the elements,'-' by reaction of metal or metal compounds with phosphine or phosphorus trichloride,'"' by thermal decomposition of a metallic phosphate or phosphite,"-'8 and by molten salt electrolysis.19 Electrolytic preparation of phosphides of titanium, manganese, and chromium from their oxides is reported in this paper. An externally heated 3-in.-ID by 6-in.-deep graphite cell, that served as the anode as well as a container for the electrolyte, was used in these investigations, and a suspended, centrally positioned graphite rod served as the cathode. A closely fitting silicon carbide furnace liner minimized atmospheric oxidation of the crucible. Electrolyses were performed for predetermined periods and current settings. Preliminary research had indicated the more efficient current and potential settings that could be used. Upon completion of the deposition period, the deposit was hot-stripped from the cathode. The mass of crystalline deposit, plus occluded and adhering salt, was crushed to minus 10 mesh and hot-leached in dilute hydrochloric acid. The leached crystalline material was water-washed, dried, and sampled for analysis. Products were identified by X-ray diffraction and standard analytical procedures. Electrochemical studies were initiated to establish the optimum conditions necessary to produce manganese phosphide (MnP), titanium phosphide (Tip), and chromium phosphide (CrP). Among the factors studied were the operating temperature, the imposed current, and the electrolyte system. If the temperature, or imposed current, was too high, deposition of phosphorus resulted, and if either were too low, partially reduced lower oxides were deposited. The operating conditions established for repetitive high-quality production of metal phosphides of the MP structure are presented in Table I. The metal phosphide crystals varied in size, but all had a definite metallic appearance. Typical are the crystals of CrP shown in Fig. 1. Evaluation data and analysis of the crystals are presented in Table 11. Efforts to measure resistivity of these three compounds over the temperature ranges of 250o to 400°K were hampered by the small physical size of the crys-

Jan 1, 1968

By Brian F. Dyson

The surface tensions at 1550°C of some Fe-S alloys (in the range 0.008 to 0.052 wt pct S), Fe-Sn alloys (0.31 to 48.4 wt pct Sn), Fe-P alloys (0.038 to 2.38 wt pct P), Fe-Cu alloys (2.15 to 22.8 wt pct Cu), and Fe-1 pct C-S alloys (0.005 to 0.076 wt pct S) along with the surface tension of the base iron have been measured by the sessile-drop method. A mean value of 1754 dynes per cm was found for the surface tension of the base iron. Sulfur was found to be highly surface-active, the surface-tension results being in quantitative agreement with existing data. Tin and copper were found to be less surface-active than sulfur while phosphoms was completely nonsurface-active. The surface tensions of Fe-1 pct C-S alloys were found to be lower than those of the Fe-S alloys containing the same sulfur content. This was shown to be a mmzifestation of the increase in the thermodynamic activity of suZfur by carbon. It is only in recent years that attempts have been made to measure the surface tension of liquid iron of known high purity.1-3 Earlier measurements4-7 were made on liquid iron containing variable amounts of what are now known to be surface -active solutes. The exact value of the surface tension of liquid iron is still, however, open to some doubt. Halden and Kingery' reported a value of 1720k 34 dynes per cm at 1570°C, Kozakevitch and Urbain8 gave 1790k 25 dynes per cm at 1550°C, while Van-Tszin-Tan et al. obtained a value of 1865k 37 dynes per cm at 1550°C. The first systematic investigation into the effect of controlled solute additions on the surface tension of iron was made by Halden and Kingery.' They showed that sulfur and oxygen were highly surface-active, whereas nitrogen was only slightly active, and carbon inactive. A subsequent investigation by Kingery indicated that two other group-6B elements, selenium and tellurium, were also surface-active. This highly surface-active nature of sulfur and oxygen has recently been substantiated by Kozakevitch and Urbainla and Van-Tszin-Tan et al. l1 Kozakevitch and Urbainl2 have also conducted an experimental survey of the effects of a number of metals on the surface tension of liquid iron. Their surface-active nature was, in all cases, less than that of the group 6B elements. The present investigation was undertaken to study in more detail the surface tensions of dilute Fe-S alloys and to measure the surface tensions of binary alloys of iron containing phosphorus, copper, and tin. The effect of sulfur additions on the surface tension of Fe-1 pct C alloys was also determined. EXPERIMENTAL PROCEDURE The sessile-drop method was employed in the present investigation. An apparatus was built similar in principle to that described by Humenik and Kingery.lS It consisted of a horizontal silica tube, which could be evacuated to pressures less than 10-5 torr, with its central portion surrounded by a water jacket within which was a high-frequency coil. This generated heat in a tantalum susceptor placed inside the silica tube, which in turn radiated heat to the specimen mounted on a recrystallized alumina plaque. Temperatures were measured by an optical pyrometer and photographs of the molten drop were taken on a fixed-focus plate camera giving a magnification of X2. Surface-tension values were determined from the resultant drop using the method described by Baes and Kellogg.l4 The high vapor pressure of molten iron made it necessary to conduct all the experiments under a 1/4 atm of argon (greater than 99.995 pct purity). The analysis of the base iron used in the investigation is given in Table I. Each sample was approximately 3 g in weight and had a hemispherical base to ensure a uniform advancing contact angle on melting. The iron alloys were prepared individually in the sessile-drop apparatus by drilling a hole in the top of each sample and adding the required amount of solute, the drops being analyzed after the experiment. This method of preparation had the advantage of ensuring a consistent minimal contamination by oxygen due to refractory attack and also allowed surface tension to be measured at the same time. Every precaution was taken to ensure that the specimen was not contaminated by grease when it was introduced into the apparatus, the samples being cleaned in acid, dried in alcohol, and rinsed in petroleum ether. All handling was done with tweezers. Once the specimen had been placed inside the susceptor, the furnace was evacuated and the Sample leveled. The furnace was then degassed at approximately 1000"C before the argon was introduced. In every case the surface tension was determined at 1550" C.

Jan 1, 1963

By Olav Klomstadlien

The lean, but extensive iron ore deposits of the Dunderland Valley north of Mo i Rana, Norway, are the raw material base for Rana Mines, a division of the state-owned A/S Norsk Jernverk steel mill. The iron bearing minerals are magnetite and specular hematite. The magnetite/hematite ratio varies considerably both within each deposit and from one deposit to another. The ore bodies that lend themselves to mining have generally a thickness of 30-60 m grading 30-35% Fe and 0.15-0.25% P. The grain size varies from 0.05 to 2.5 mm. The fine grained ores are hard while the coarse grained ores are soft and easy to grind. The A/S Norsk Jernverk steel mill operates both a sinter and a pellet plant, and this necessitates production of two types of concentrates. The present flowsheet is shown in [Fig. 1]. The crude ore from the pits is crushed in a 1.07-m gyratory crusher with an open side setting of 12.7 cm. The crusher product is transported by rail to the concentrator located 25 km from the mines. The ore is fed by twelve 1.22 X 1.83 m vibratory feeders onto conveyor belts which carry the ore to a surge bin ahead of the autogenous mills. The feed rate is automatically adjusted to maintain a set power load at a level suitable for the ore type being processed. The mills operate in closed circuit with twelve dual-drum screens equipped with a 0.8-mm screen cloth. Oversize is returned by gravity to the mill feed while undersize flows to the gravity separation section which consists of Humphrey spirals in three stages. The ores are very heterogenous and analysis may vary quite considerably. The quantitative need for concentrate in the steel mill may also change rapidly. The process in the concentrator must therefore be easily changed, and consequently alternative process lines have been established. This is indicated with the dotted lines in the flowsheet. Apatite is removed by flotation by fatty acids to give a final sinter concentrate of 63% Fe and 0.020% P or less. Pellet concentrate contains about 65% Fe and less than 0.020% P. The fineness is about 1500 Blain.

Jan 1, 1981

By E. H. Phillips, A. F. Keenan

6.2-1. Historical Development. Hammering on hand-held drill steel was the earliest type of percussion drilling. It was not until 1838 that Singer developed a steam-operated drilling machine that lifted a drilling bar and let it drop by gravity. J. J. Couch of Philadelphia patented the first percussion drill in 1849. His machine was a steam drill which literally hurled the drill bar at the rock and retracted it by means of a ratcheted wheel. Later J. W. Fowle added automatic rotation of the steel. In 1871, Simon Ingersoll patented a rock drill mounted on a tripod which permitted drilling holes at any angle, vertical to horizontal. Up to the turn of the century, percussion drills in use were piston-type drills. The drill steel was solid and attached to an extension of the drill piston. Hole cleaning was accomplished by the pumping action of the steel in the hole. Down-holes were drilled wet and cleaned with a blow pipe while up-holes were drilled dry, allowing the cuttings to drop out by gravity. The forerunner of our present hammer drill was the free-piston drill which was first patented in 1884, by Sargent. Because solid drill steel was used, it did not successfully clean down holes. J. G. Leyner solved the problem of applying the hammer drill principle to down-hole and horizontal-hole work in 1897. The key was to pass com- pressed air and water through hollow drill steel to clean the hole. Leyner's work on valves and rotation mechanisms increased the blows per minute of hammer drills from 300 or 400 up to 1800 and more blows per minute and made possible the first lightweight drilling machines. The development of automatic feeds followed. 6.2-2. Percussion Drills. TYPES OF DRILLS. There are two types of percussion drills in use today; the piston drill and the hammer drill. In the

Jan 1, 1968

By F. C. Farnham

THERE has been very little, if any, uniformity in the reference datum used for magnetometer surveys. It has been the practice to choose a base station at which the magnetic field is assumed to be normal and call the difference in field strength between a given station and this base the anomaly at the given station. For small-scale surveys latitude and longitude corrections may or may not be applied, but for large-scale surveys such corrections usually are applied. The United States Coast and Geodetic Survey maps showing lines of equal magnetic intensity are commonly used to determine the normal latitude and longitude variation by scaling values from the map for given points and computing the change per mile north and the change per mile east. This method has been quite satisfactory for isolated surveys, but when two surveys originating at different base stations were extended until they joined, difficulty arose, not only because of discrepancies between base-station values, but also because of differences between the latitude and longitude correction factors used for the separate surveys. It is the purpose of this paper to describe a reference datum for magnetometer surveys which, it is believed, will eliminate most of the difficulty arising from this source. In order to be satisfactory, a general datum for magnetometer sur-veys should be as close as possible to the observed field and still he based on some assumed distribution of magnet poles, in order that the "normal" value of any component of the field for any given point may be computed to as many significant figures as desired. Such a field has been com-puted, and a comparison of the intensity of its vertical component with the average vertical intensity for the United States as shown by the U.S.C.G.S. map of lines of equal intensity for 1935 is shown in Fig. 1.

Jan 1, 1939

By THOMAS G. FEAR

THE COAL DIVISION started its share of the annual meeting Monday morning with a study of coal classi fication. A. C. Fieldner was in the chair. The report of the tellers of the ballot for division chairman, stating that Thomas G. Fear had been elected to that office, was read by M. D. Cooper. Mr. Fear acknowledged the honor in a few words. In reviewing the history of the Coal Classification Committee the chairman pointed out that this was its third symposium, the last previous one having been held at the 1930 Annual Meeting. Throughout its work the com¬mittee has had the active cooperation of the Canadian workers who are interested in the subject which should result in a uniform scheme of classification in Canada and the United States. F. E. Lathe, of the National Research Council, Ottawa, abstracted the first two papers of the session entitled "Determination of the Alkali-Soluble Ulmins in Coal," by Edgar Stansfield and K. C. Gilbart, and "Moisture Determination for Coal Classification," by the same authors. The third paper "Condition of Water in Coals of Various Ranks"' was presented by its author, A. W. Gauger. Written discussions of these papers were presented by H. C. Porter and Gilbert H. Cady. In the oral discussion which followed, W. T. Thom, Jr., brought out the advisability of considering age as a factor in classification. Mr. Fieldner favored retaining bed moisture as a partial classification basis, stating that a review of many coal analyses revealed a remarkable consistency in this item in samples from a given mine particularly where the moisture content was not high. Mr. Porter pointed out that the structure and porosity of coal often have much to do with its moisture content and that these vary in different parts of a seam, particularly in anthracite. Mr. Gauger expressed doubt as to whether the Stansfield method gives the true moisture content of coal, which is needed for classification purposes.

Jan 1, 1932

By Willard L. Hunter

Four solvent extraction systems were studied to determine their efficiency jor extraction and separation of tantalum and columbium. Aqueous feed solutions of varying HF-HCl concentrations and metal content were contacted with equal volumes of cyclohexanone, 3-methyl-2-butanone, and 2-pentanone and solutions of varying HF-H2S04 concentrations were contacted with equal volumes of 2-pentanone. One multistage continuous test was made in a polyethylene pulse column using cy clohexanone as the organic phase. In each system studied, columbium and tantalum purities in excess of 95 pct with respect to each other were obtained in single-stage tests at low acidities in the feed solution. Separation factors ranging from 1700 to 2400 were obtained when rising HF-HCl mixtures in the aqueous phase. Best results were obtained when a solution of HF-H2S04 was used as the aqueous phase and 2-pentanone as the organic phase. A separation factor in excess of 6000 was obtained in one stage with aqueous solution concentrations of 2 _N HF and 2N H2S0,. When acid concentrations were increaszd to 52 HF and 10 _N H2S0,, 99.9 pct of the tantalum and 98.2 pct of the columbium initially present in the feed solution were transferred to the organic phase. The separation of columnbium and tantalum obtainable by means of the solvent extraction systems presented in this paper was found to corn -pare favorably with other systems, including the HF-H2SO4-methyl isobutyl ketone system currently used by most producers for the extraction and separation of these metals. TANTALUM and columbium are always found together in minerals of commercial significance, although the proportion of the two metals in ores varies within broad limits. Columbium is estimated to be 13 times more abundant than tantalum. Five methods generally employed for the separat:ion of these metals are: 1) fractional crystallization (the Marignac process),2 2) solvent separation, 3) fractional distillation of their chlorides, 4) ion exchange, and 5) selective reduction. Of these methods, the one currently used by industry to the greatest extent is that of solvent separation. One of the early technical developments in solvent separation of tantalum from columbium was reported by the Bureau of Mines: the HF-HC1-methyl isobutyl ketone system; data were presented for both laboratory and pilot-plant experimentation.3 Of twenty-eight organic solvents tested for their ability to extract tantalum from an HF-HC1 solution of columbium and tantalum, 3-pentanone (diethyl ke-tone), cyclohexanone, 2-pentanone, and 3-methyl-2-butanone were chosen for further study. Data on the HF-HC1-diethyl ketone system has been published4 and data describing the use of cy clohexanone, 2-pentanone, and 3-methyl-2-butanone as the organic phase are included in this report. RAW MATERIAL The source of tantalum and columbium oxides for this study was ('Geomines" tin slag from the Manono Smelter, Cie Geomines, Gelges, S.A., Congo. In order to extract the valuable Ta-Cb content, the slags were carbided, chlorinated, and the sublimate from chlo-rination was hydrolized and washed free of chloride with water. The washed material was air-dried and stored in a stoppered container. Throughout the paper, "feed material" refers to this mixture of hydrated oxides which was employed because of its high solubility in aqueous solutions. Typical analysis of the hydrated oxides is shown in Table I. I) HF-HC1-CYCLOHEXANONE SYSTEM Batch Separation. Effect of Acid Concentration. To determine the effect of varying the acid concentration upon the transfer of tantalum and columbium, a series of tests was made in which approximately 2.5 g of feed material was added to 25 ml solutions of 2, 4, 6, 8, and 10 N HF and 0 through 5 N HC1. Tantalum pentoxide concentration of the solu%ons was approximately 21 g per liter and columbium pentoxide was 14 g per liter. These starting solutions were shaken with equal volumes of cyclohexanone in 100 ml polyethylene bottles for 30 min. The phases were carefully separated in 125 ml glass separatory funnels. The time of contact of the solutions with the separatory funnels was kept at a minimum to reduce silica contamination. The measured phases were separated into 400 ml polyethylene beakers and the metal contents of each were precipitated by addition of an excess of ammonium hydroxide. Precipitate from each phase was filtered on ashless filter paper, ignited at 800" to 1000°C for 45 min, weighed, and analyzed by X-ray fluorescence.5 Data tabulated in Table I1 and illustrated in Fig. 1, show that maximum separation of tantalum from columbium for each HF concentration was obtained with no HCl present. The purest tantalum product was obtained with some HCl present. The highest separation factor was obtained at 2 N HF and

Jan 1, 1970

By James Gayley

The development of blast-furnace practice in America in the direction of large yields is mainly the history of our working since the year 1880, as the advancement that has been made in the last decade is greater than that in the third of a century previous. A new era in the manufactnre of pig-iron began in 1880 with the putting in blast of the Edgar Thomson furnaces. These furnaces at once leaped to the front as pig-iron producers, and have maintained that position—with but one brief interruption—ever since. I shall, therefore, confine myself mainly to a description of these works, showing the changes in design and practice by which these results have been achieved. In order to show more clearly the progress that has been made since 1880, I shall refer briefly to the best work that was done in the ten years previous to that time. The Struthers furnace, in Ohio, was one of the first to attract attention in the matter of large outputs. This furnace was 55 feet high, 16 feet in diameter of bosh, 9 feet in the hearth, and about 8 feet 6 inches at the stock-line. The fuel was raw coal. This furnace, in December, 1871, made 1602

Jan 1, 1891

By Theodore Simons

The rapid and comparatively recent development of flotation has opened so fascinating a field for study and research that the older processes of gravity concentration no longer receive the attention they deserve. The early work of Munroel and Richards12 and the more recent contributions by Clevenger and Coe,3 Laist and Wiggin,4 Ammon,5 Bardwell,6 Crowfoot,' and Hayden8 (to mention only some which have appeared in our own Transactions) and by Schu1z,9 have furnished so much data that to offer something new seems a difficult task. It is still possible, however, to present known facts from a different point of view, and, with this in mind, the writer has undertaken to express basic principles of gravity concentration in terms of simple mathematics and mechanics; the conclusions thus reached will be found to correspond, in general, with those obtained by experimental methods. Rittinger, in his classic Aufbereitungskunde (1867)) reached analogous conclusions by way of intricate higher mathematics, for which reason his interesting investigations have remained a sealed book to most of us. The writer hopes that a more elementary treatment of the subject, based in part on Rittinger's metheds, may arouse new interest in the study of basic principles.

Jan 1, 1923