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By Clyde E. Williams, JAMES L. GREGG

THIS review of the past year's progress in iron and steel metallurgy presents examples of only a few of the interesting or important accomplishments made in the United States. In the field of iron ore concentration increased attention was given to the study of the more difficultly separated wash ores and some progress was made in tabling. One difficulty with the table, in concentrating iron ore where the percentage of concentrate in the feed is large, has been the removal of fine silica from the thick layer .of concentrates in the cleaning zone. One company has -Made an important contribution toward the solution of this problem by an extension of the well-known plateau principle. By a special riffling of the plateau section of the table, the concentrates are crowded together. This action forces the fine silica to the top of the bed in the cleaning zone, whence the cross-flowing currents of water -can wash it into the middling product. Some work has been done on the application of froth flotation to the concentration of iron ores. Laboratory experiments were made at the Colorado School of Mines in which hematite was, successfully floated. Using oleic acid as a frothing and collecting agent and sodium carbonate as the conditioning agent, a high recovery of rich ,concentrate was obtained. A laboratory flotation unit is in use at Taconite, on the Mesabi range, and a commer-

Jan 1, 1932

By G. Krauss, W. Pitsch

The fine structure of the bcc martensite formed in an Fe-33 wt pct ATi single crystal of arrstenite is sho~on by transmission electron microscoPy to consist of combinations of transformation twins, stacking faults, deformation twins, and regular arrays of parallel screw dislocations. These structures constitute evidence for the multiple lattice-invariant deformations which operating during the formation of martensite could produce the real habit-plane scatter measured by a two-surface analysis of the plates formed in the single crystal of this investigation and reported in the literature for other Fe-Ni rnartensites. CRYSTALLOGRAPHIC theories1,2 of martensitic transformation show that the habit plane of martensite in a parent lattice is dependent in part upon an inhomogeneous distortion or lattice-invariant deformation which takes place on a fine scale within a martensite plate during its formation. Several recent theoretical papers3,4 have addressed themselves to an analysis of a wide variety of conceivable lat-tice-invarient deformations and the habit planes which they produce, while experimental investigation have been concerned with either the measurement of habit planes or the description and identification of the martensitic fine structure which reflects the nature of the lattice-invariant deformation operating during transformation. In Fe-Ni alloys with subzero Ms temperatures, the group of alloys with which this paper concerns itself, habit planes have often been found to scatter an amount greater than might be expected from possible experimental errors,5-7 and fine twinning has been identified as a major constituent of the fine structure of martensite.8-11 It has been suggested3,4 that more than one type of invariant shear occurs during martensitic transformation. This possibility has been experimentally supported12,13 by the observation of both dislocation configurations and twinning in a single martensite plate. The purpose of this paper is to report additional evidence for multiple lattice-invariant deformations in martensite and so to account for the real scatter in the habit planes of the martensite plates formed in Fe-Ni alloys. EXPERIMENTAL PROCEDURE The Fe-Ni single crystal was produced by pulling a high-purity iron and nickel charge through a single-crystal vacuum furnace in an alumina crucible. The crystal was double-melted to promote homogeneity and to increase its size by further additions on the second pass. In its final form the crystal was 4 cm in diam and 5 cm long. The nickel and carbon contents were analyzed at 32.9 and 0.006 wt pct, respectively. The austenite of this alloy first transformed to martensite by bursts at about -120°C, and, to preserve as much of the austenite as possible, all transformation was performed just below -120°C. Some observations were made on transformed samples which had been heated for 2 min at 340°C. It is assumed that the features of the martensite of these samples, Figs. 1 and 4, are the same as those of the as-quenched martensite. Orientation of the crystal by X-ray diffraction established 10.735 0.609 0.3161? as the axis of the crystal, an orientation that was checked within 2 deg by neutron diffraction. Further checks by electron diffraction of samples cut normal to the axis confirmed this orientation within the larger limits of error inherent in electron diffraction of thin foils. The X-ray orientation was the one used for the two-surface analysis of the martensite habit planes. A two-surface analysis was performed on the quadrant of the single crystal which had been oriented by both X-ray and neutron-diffraction techniques. Photomicrographs at X50 were made on two surfaces along an edge 2 cm long. Fiducial marks and the fact that many of the plates were almost completely surrounded by retained austenite made good matching of individual plates on two surfaces possible. The habit-plane trace on a surface was taken as the best line parallel to the long axis of a plate. A measure of the accuracy afforded by this criterion was provided by a family of very large plates which appeared at intervals along the entire 2 cm length of the edge. The plates all had habit-plane traces within 2 deg of one another. Many of the plates did not show midribs and, therefore, the use of midribs7 to represent habit-plane traces was not feasible in this investigation. The over-all experimental accuracy is estimated to be better than ±2 deg. Samples for transmission examination in a Siemens Elmiskop I at 100 kv were prepared by cutting 2-mm-thick discs from the single crystal, removing about 0.5 mm by chemical polishing,14 trans-

Jan 1, 1965

By Harry Klemic

Zirconium and hafnium minerals are used industrially both as minerals valuable for their chemical and physical characteristics and as ores of zirconium and hafnium. The principal zirconium-hafnium-bearing minerals, their composition, and their ranges in content of zirconium and hafnium dioxides are listed in Table 1. The supply of zirconium and hafnium is based almost entirely upon the supply of the minerals zircon and baddeleyite. Eudialyte may eventually also be of importance as a source of these elements. Zircon, which generally contains nearly 49% zirconium and between 0.4 and 1.5% hafnium, is the principal industrial mineral of this group. Baddeleyite, a commercially important but less abundant mineral, contains as much as 73% zirconium and 0.4 to 1.7% hafnium. Eudialyte has a wide range in content of these elements, but analyses of material from several localities indicate values of 6 to 11 % zirconium and 0.07 to 0.4% hafnium. Zircon is a mineral consisting principally of zirconium, silicon, and oxygen that crystallizes from magmas during the formation of igneous rocks. Zircon also occurs in veins and in metamorphic rocks. It is in the tetragonal crystal system. It commonly forms as small well-developed prisms having pyramidal terminations but also occurs as irregular-shaped grains. Zircon has a hardness of 7.5 on the Mohs' scale. Its specific gravity is commonly between 4.68 and 4.70 (Dana, 1932), but the specific gravity varies somewhat depending upon com- position and state of alteration. Zircon has no good cleavage directions and is brittle, breaking with a conchoidal fracture. Zircon of the composition ZrSiO, would contain 67.2% Zr02 and 32.8% SiO2. However, in addition to about 1 % of hafnium, minor amounts of thorium, uranium, rare earth elements, yttrium, calcium, magnesium, iron, aluminum, phosphorus, and hydrogen, and trace amounts of other elements are commonly present in the mineral (Frondel, 1957). Radiogenic lead and other daughter products from the radioactive decay of uranium and thorium also accrue in the mineral. Radiation damage to the structure of zircons that contain appreciable amounts of uranium and thorium may alter the internal structure of the crystals to

Jan 1, 1975

By Robert L. Frantz

Progress and improvement continue to be the bywords of a dynamic coal industry. The industry continues to gain strength and expand its horizons in the face of competition from atomic energy and the problems of restrictive legislation. The direct contribution of coal mining and transportation to the national economy is about $3 billion a year ac- cording to a study made by the National Coal Policy conference. Coal remains the backbone of the power industry producing almost two-thirds of all the electrical energy generated by fossil fuels and one-quarter of all the energy consumed in the nation. Power supplied by electric utilities increased 6.9% last year. The chairman of the Federal Power Commission predicted a 7.5% growth rate until 1980 for the nation's electric output. Some 80,500 MW of fossil fired power plant capacity are on order or under construction before 1974, compared to a present capacity, all sources, of about 290,000 MW. The comparable new additions of nuclear power plants is expected to total about 51,000 MW.

Jan 2, 1969

By Thomas S. Blair

I FEEL a certain sense of responsibility in bringing before you the subject of the direct process in iron manufacture. I am aware that, in such a body as I have now the honor of addressing, there are few who are not already so well informed upon its past history that it would be a weariness to them to listen to anything else than an account of practical success. Yet, to claim that success involves so much that, if I do not make good my claim, I deservedly expose myself to severe criticism. The whole literature of the art, so far as it relates to the direct process, is, up to this time, but a history of failure. It is safe to say that more money, time, and talent have been fruitlessly spent in the pursuit of this object than in all the other unsuccessful efforts in the whole line of iron metallurgy. A distinguished authority in patent law has remarked that " the invention records of the United States and of foreign countries are filled with the waifs and abandoned relics of these abortive struggles." Dr. Percy, whose great work may be taken as an epitome of all that was worth mention, whether useful or curious, in pig-iron metallurgy, up to the date of its publication (1864), after giving elaborate accounts of various attempts at the direct process, condenses his own opinion of all that had been then effected, into a brief but summary comment upon a pamphlet of one of the sanguine inventors who had said: "It is evident that the present mode of working iron

Jan 1, 1874

By Paul J. Sirkegian

A detail of the guide rollers is shown on Fig. I; and Fig. 2 shows a photograph of a guide roller that has been in service for several months on the haul-back cable. The former practice of supporting and guiding the haul-back cable on slusher hoists at Kimberly was accomplished by using the conventional type of snatch-block pulley, but it was found that an excessive amount of cable whipping and unreasonable wear on both rope and pulley resulted from this type of cable support. The guide, which is wholly made in the Corporation's shops, consists of two vertical and one horizontal roll assembled in a frame that is lagged to the cap timber in a slusher drift. In some slusher drifts more than one guide-roller assembly is used, depending upon the length of the drift. The installations usually are placed at 30-ft. intervals. We have found by actual experience that these rollers have increased the life of the haul-back cable approximately 200 per cent, as compared with the usage of the conventional sheave-block pulley. Cable Care The underground rigging crew and the slusher operators are trained in rope splicing. No cable clamps or knots are permitted on slusher cables and all cable "eyes" are spliced. The standard practice has been to use preformed cables of ?-in. diameter for haulage and ½-in. diameter for the haul back. The preformed cables have proved to be important factors for safety in use and speed in making splices. No external lubrication is used on the cables. It has been found that dry ropes have about 400 per cent longer life than those that were lubricated under these operating conditions. An accurate record is kept of all cable life and the tonnage moved by the slushers in each working place, and if the rope wear is excessive in any particular working place, an investigation is made to determine the reason. Wire-rope Sling for Snatch-block Anchor The rope sling is shown by Figs. 3 and 4. These slings support the snatch-block pulley for the haul-back rope. The standard practice at Kimberly is to use a roller-bearing snatch-block pulley 10 in. in diameter. The snatch-block housings are equipped with a clevis attachment in preference to swivel hooks, as it has been found that the more rigid clevis keeps the cable in better alignment. The snatch blocks are hung from the cable sling, which is wrapped around the posts of the drift sets as shown on Fig. 3. This method of anchoring the pulley provides better anchorage and flexibility than those of the rigid or spring-mounted types. When the slusher-drift headings are being advanced, the snatch blocks are hung from a "gin" pole ahead of the last set of timbers' An employee is assigned on each production shift to take care of the lubrication of all slusher hoists that are being used and he is provided with tools for minor repairs.

Jan 1, 1946

By A. E. Weissenborn

Current knowledge of the substantial resources of zinc that exist in northwestern Washington is reviewed. These zinc-lead deposits are all associated with the Kootenay Arc, a narrow arcuate belt of folded and faulted rocks that dominates the regional structure of Stevens and Pend Oreille Counties and adjacent parts of British Columbia. The deposits of the Arc are only part of a major lead-zinc silver metallogenic province that includes the deposits of the Coeur d'Alene district and the famed Sullivan ore body of Kimberly, British Columbia. Most, but by no means all the zinc-lead deposits of the Kootenay Arc are in carbonate rocks. They occur in several stratigraphic units, and in different parts of the Arc are quite diverse in character. The deposits appear to have undergone a complex geologic history and have not necessarily all been formed at the same time or by the same geologic processes.

Jan 1, 1976

By A. A. Jr. Smith, J. S. Smart

The controlled amounts of phosphorus, arsenic, sulphur or selenium found in commercial coppers perform a variety of highly useful functions. Indeed, a large segment of modern copper technology is essentially dependent upon the presence of one or more of these elements. Consequently, the literature contains many references to their effects but the scope is broad and has been only partly covered. New data are presented herewith directed toward a better understanding of the basic behavior of these elements in copper, with particular emphasis on the composition range o to 0.05 per cent. These data are a part of a general program of research on the effects of impurities on the properties of oxygen-bearing and oxygen-free copper, other portions of which have been reported previously. Schematically, the behavior of individual elements is determined from measurements of conductivity and softening temperature,'v2 and the binary alloys employed are synthesized from high-purity copper in order to eliminate interference from the effects of extraneous impurities. Alloys of selected composition were first prepared in the oxygen-free form by continuously casting the melts in the form of %-in. diameter rod. Oxygen was added subsequently to portions of the alloys, either by remelting or by diffusion at 8jo°C. from a surface scale. Test wires wcre drawn one B. and S. number per pass, using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in., and a final cold reduction of 75 per cent to 0.081 in. Oxygen-bearing slugs made by remelting nere hot-rolled to 4ia in.. drawn to 0.162 in., annealed for 30 min. at 6o0°C. and cold-drawn 75 per cent to 0.081 inch. The alloys containing phosphorus, having been compounded very early in the program, were prepared in the form of 3i6-in. rod, and processed to wire with only the last three intermediate anneals listed above, all of these having been conducted in commercial nitrogen. In addition, the conductivity anneals on these alloys were also performed in the same atmosphere, and the small amount of oxygen present as an impurity in the gas resulted in some loss of accuracy at temperatures of 700' to 8o0°C., as will be shown later. Subsequently, the anneals for all oxygen-free alloys were conducted in hydrogen to prevent oxidation, and purified nitrogen was employed only for oxygen-bearing samples. All conductivity anneals wcre of one hour duration followed by a rapid quench in 10 per cent HZSO*. Effect of Phosphorus The widespread use of phosphorus as a deoxidant has resulted in universal appreci-

Jan 1, 1946

By A. A. Jr. Smith, J. S. Smart

The controlled amounts of phosphorus, arsenic, sulphur or selenium found in commercial coppers perform a variety of highly useful functions. Indeed, a large segment of modern copper technology is essentially dependent upon the presence of one or more of these elements. Consequently, the literature contains many references to their effects but the scope is broad and has been only partly covered. New data are presented herewith directed toward a better understanding of the basic behavior of these elements in copper, with particular emphasis on the composition range o to 0.05 per cent. These data are a part of a general program of research on the effects of impurities on the properties of oxygen-bearing and oxygen-free copper, other portions of which have been reported previously. Schematically, the behavior of individual elements is determined from measurements of conductivity and softening temperature,'v2 and the binary alloys employed are synthesized from high-purity copper in order to eliminate interference from the effects of extraneous impurities. Alloys of selected composition were first prepared in the oxygen-free form by continuously casting the melts in the form of %-in. diameter rod. Oxygen was added subsequently to portions of the alloys, either by remelting or by diffusion at 8jo°C. from a surface scale. Test wires wcre drawn one B. and S. number per pass, using four 30-min. 600°C. anneals at 0.3125, 0.257, 0.204 and 0.162 in., and a final cold reduction of 75 per cent to 0.081 in. Oxygen-bearing slugs made by remelting nere hot-rolled to 4ia in.. drawn to 0.162 in., annealed for 30 min. at 6o0°C. and cold-drawn 75 per cent to 0.081 inch. The alloys containing phosphorus, having been compounded very early in the program, were prepared in the form of 3i6-in. rod, and processed to wire with only the last three intermediate anneals listed above, all of these having been conducted in commercial nitrogen. In addition, the conductivity anneals on these alloys were also performed in the same atmosphere, and the small amount of oxygen present as an impurity in the gas resulted in some loss of accuracy at temperatures of 700' to 8o0°C., as will be shown later. Subsequently, the anneals for all oxygen-free alloys were conducted in hydrogen to prevent oxidation, and purified nitrogen was employed only for oxygen-bearing samples. All conductivity anneals wcre of one hour duration followed by a rapid quench in 10 per cent HZSO*. Effect of Phosphorus The widespread use of phosphorus as a deoxidant has resulted in universal appreci-

Jan 1, 1946

By H. A. Coy, James A. Noble

The Mascot mines of the American Zinc Co. of Tennessee are situated at Mascot, Tenn., 14 miles northeast of Knoxville, on the Southern Railway. The district is centrally located in the Great Valley, or Appalachian Valley Province. Prior to 1900, a small output of zinc was obtained from oxidized ore mined in open pits. In 1900, a shaft was sunk to sulfide ore, and in 1903, a second shaft was put down, neither being as deep as 200 ft. The American Zinc Co. of Tennessee began drilling in 1911, and outlined an ore-body to which its No. 1 shaft was sunk, to a depth of 365 ft. Since that time, the American Zinc Co. of Tennessee has been the only operator in the district. The Federal mining laws have never been in operation in Tennessee and mining lands are as irregular in boundary and area as farm lands. Ownerships are generally held in fee. In most cases the surface and mineral rights are transferred together. Electric power is supplied at 66,000 volts by the Tennessee Power Co., from a hydro-electric plant at Parksville, Polk County, Tenn., 100 miles from Mascot. No other power is used, but an emergency steam plant is held ready in case of interruption of service. Labor is all native and non-union. Negroes are employed for most of the shoveling, and for a few miscellaneous jobs, but for almost no other work. Exploration Exploration is carried ahead of mining largely by surface drilling. Both churn and diamond drills are used. Holes are not spotted according to geometric plan, but to block out ore outlines with the least number of holes. Churn-drill cuttings from each 5-ft. run are mounted for formation record, and in ore ground, all the bailings from each 3 ft. of advance are sampled and assayed. Diamond-drill cores are sampled and a specimen core filed for formation record. In ore ground, all the core

Jan 1, 1925

P. Herasymenko (New York University, New York) —The authors' experiments on equilibria between water vapor and liquid synthetic slags represent a valuable contribution to our knowledge of the nature of liquid slags. They can be regarded as a proof of ionic splitting of water molecules dissolved in slags. The assumption that water dissolved in slag was com- pletely ionized was made in my report on hydrogen equilibria in steelmaking as early as 194010. In that paper, the first systematic data were given on the content of ionized hydrogen in acid and basic open-hearth slags. The paper probably escaped the notice of the authors, although they mention the articles published later by other investigators who reported erratic and

Jan 1, 1958

By Roshan B. Bhappu, Ronald J. Roman, Dexter H. Reynolds

The reaction between manganese dioxide and molybdenite in a water- sulfuric acid medium was studied at atmospheric pressure and from 25° to 103°C. Both solids are dissolved to give, as final products in solution, Mo(VI), S(VI), and Mn(II). Stoichiornetric relationshifis are most simply represented by the equation MoSz + YMnO2 + 15H+ - HMoO-4 + 2HSO-4 + 9Mn++ + 6H20 The rate of this reaction was found to be dependent on temperature, manganese sulfate concentration, acid concentration, and, in a complex way, the surface areas of both manganese dioxide and molybdenite. Both the total amount of manganese dioxide and tnolybdenite and the ratio of manganese dioxide to molybdenite played a part in determining the over-all rate of the reaction. The effect of acid concentration on the rate was also dependent on the ratio of manganese dioxide to molybdenite. SEVERAL reports in the literature describe reactions using manganese dioxide in water-sulfuric acid media as an oxidizing agent. Nearly all previous work describes interactions between an ion and manganese dioxide, such as the oxidation of ferrous to ferric iron,' or the interaction between a molecule in solution and manganese dioxide, such as the oxidation of toluene to benzaldehyde.2 Only a few references describe the use of solid manganese dioxide to oxidize another solid in sulfuric acid. One report3 states, "Manganese dioxide in dilute sulfuric acid solutions had no beneficial effect (in leaching copper from chalcopyrite), but in more concentrated acid solutions the rate of solution was about the same as that for permanganate." In 1902 a German patent4 described a process which used manganese dioxide in strong (50°Be') sulfuric acid for oxidizing chromite ores to soluble iron and chromium salts. The process consisted of mixing the sulfuric acid with the finely ground ore and manganese dioxide. The pulp was then heated to about 120°C and an electric current passed through it. The manganese dioxide apparently dissolved in the strong, hot acid solution, oxidized the iron and chromium and itself was reduced to manganese 11! then was oxidized at the anode back to manganese dioxide, and the cycle repeated. An extensive study5 of the kinetics of the oxidation of pyrite with manganese dioxide indicated that in dilute sulfuric acid solutions (about 0.1 N) and at elevated pressures the dissolution of the pyrite was brought about by air oxidation of the iron to ferrous sulfate, followed by manganese dioxide oxidation of the ferrous sulfate to ferric sulfate. The mechanism proposed by the authors involved the oxidation of the iron at the surface of the manganese dioxide. Also! the oxidation of sulfide sulfur to sulfate was credited to the oxygen in the air, not to the manganese dioxide. Since the metallurgical literature is lacking in information concerning the use of one solid to oxidize another solid. the current investigation was under-

Jan 1, 1965

By Thomas Egleston

All industrial establishments whose operations depend upon chemical reactions use gases. In the simplest case the oxygen of the atmosphere, heated or not, as the case may be, is used, and in other cases, gases which are produced by a special apparatus of more or less complex composition. The manufacturer depends, for the success of his operations, entirely upon having these gases arrive at the right time, in the proper proportions, at the required temperature. It often requires but a slight variation in their composition to make a given process a success or a failure. In most cases the gas used is formed from fuel, and according as variations in its composition are produced by alterations in the manner of charging the grate, not only different, but often directly opposite, results are obtained. The great industrial question of the present time, and one upon which the prosperity of the world depends, is how to get the greatest amount of useful effect from fuel, whether the caloric is used directly or is transformed into horse-power. In almost all industrial pursuits this translates itself into the question of how to construct a fireplace and its adjuncts in such a way that the heat of the flame and of the products of combustion shall be made to produce a maximum effect. Unfortunately, until very recently, except by comparison, there was no means of ascertaining whether the loss of useful effect was 80, 40, or 20 per cent. of the total amount of fuel employed. It seems now strange that there should have been furnaces so constructed as to produce 20 per cent. of carbonic acid in the fireplace, but this has been proved by analysis to have been true. It does seem incredible that, notwithstanding the immense number and variety of furnaces used for different processes, and the great difference in kind, quality, and quantity of fuels consumed, there should formerly have been used for them all, the same stereotyped fireplace, varied only in its dimensions of height, length, and breadth. It is true that, with a good fireman, excellent effects may be, and have been, produced, but the manufacture is here, as in many other cases, dependent on the intelligence of the workman, a very uncertain reliance for capital to rest upon. The workman, unless he receives a prime for fuel saved, or is fined for excessive use of it, may be said

By T. Prof. Egleston

ALL industrial establishments whose operations depend upon chemical reactions use gases. In the simplest case the oxygen of the atmosphere, heated or not, as the case may be, is used, and in other cases, gases which are produced by a special apparatus of more or less complex composition. The manufacturer depends, for the success of his operations, entirely upon having these gases arrive at the right time, in the proper proportions, at the required temperature. It often requires but a slight variation in their composition to make a given process a success or a failure. In most cases the gas used is formed from fuel, and according as variations in its composition are produced by alterations in the manner of charging the grate, not only different, but often directly opposite, results are obtained. The great industrial question of the present time, and one upon which the prosperity of the world depends, is how to get the greatest amount of useful effect from fuel, whether the caloric is used directly or is transformed into horse-power. In almost all industrial pursuits this translates itself into the question of how to construct a fireplace and its adjuncts in such a way that the heat of the flame and of the products of combustion shall be made to produce a maximum effect. Unfortunately, until very recently, except by comparison, there was no means of ascertaining whether the loss of useful effect was 80, 40, or 20 per cent. of the total amount of fuel employed. It seems now strange that there should have been furnaces so constructed as to produce 20 per cent. of carbonic acid in the fireplace, but this has been proved by analysis to have been true. It does seem incredible that, notwithstanding the immense number and variety of furnaces used for different processes, and the great difference in kind, quality, and quantity of fuels consumed, there should formerly have been used for them all, the same stereotyped fireplace, varied only in its dimensions of height, length, and breadth. It is true that, with a good fireman, excellent effects may be, and have been, produced, but the manufacture is here, as in many other cases, dependent on the intelligence of the workman, a very uncertain reliance for capital to rest upon. The workman, unless he receives a prime for fuel saved, or is fined for excessive use of it, may be said

Jan 1, 1874

By J. O. Whiteley, C. Dietz

It is difficult to give a refining outline that may be followed for any and all combinations of the platinum metals; different combinations require different methods of attack. This paper does not pretend to go into all of the reactions of the metals of the platinum group, but will outline the commercial refining of platinum scrap. Typical Platinum Scrap As a concrete case, let us take 100 oz. of miscellaneous scrap, made up of jewelry scrap, dental scrap and laboratory ware. This lot will contain some platinum, palladium, iridium, ruthenium, rhodium, gold, silver and copper. The first problem is to get all of the metals in solution. If the scrap is principally platinum, palladium and gold, a treatment with aqua regia is the course to pursue; but if the scrap contains alloys high in iridium or ruthenium, aqua regia will act too slowly. In the case in hand, we are going to presume that we have scrap high in iridium and ruthenium, and proceed accordingly. Obtaining Residue A Place the scrap, together with six times its weight of granulated test lead, in a solid carbon crucible. This crucible may be placed inside a clay graphite crucible packed with charcoal, to prevent the excessive oxidation of the carbon crucible by the furnace blast. Place a tight cover on the carbon crucible; heat gradually to a good red heat and allow it to soak in the heat for 4 or 5 hr. After the leaded mass is cool, dissolve in dilute nitric acid (1-6) on a steam plate or sand bath. This dissolves practically all of the lead and most of the palladium, silver and copper, together with seme of the platinum and rhodium, and leaves the iridium, ruthenium, gold, and most of the rhodium and platinum as a finely divided residue. Siphon off the clear solution and treat the residue with another portion of dilute nitric acid to insure the solution of the lead and copper. The second nitric acid solution is added to the first, and the residue is filtered on suction and washed thoroughly with hot

Jan 1, 1928

By A. W. Furbank

In reviewing the aerial cameras produced in different countries, it becomes apparent that in nearly all of them an attempt has been made to secure the greatest possible angle of view. This angle, of course, is determined by the objective. The objectives most commonly in use in aerial cameras have a maximum angle of 65". The objective developed for this new Zeiss camera combines freedom from distortion and brilliant definition, with an angle of 95". Aerial mapping, it is claimed, has been placed on a different economic basis, and new possibilities presented, particularly in connection with automatic stereoscopic plotting instruments, to which some short references are made. One way of enlarging the angle of view is to couple several instruments with their axes convergent, thereby producing a multilens camera. Typical of cameras of this sort in the United States is the Bagley four-lens camera, which later was developed into the five-lens camera (T3-A) of the U. S. Air Corps. More recently, in order to get away from the unfavorable Maltese cross image field of the five-lens camera, and to obtain a more practical form, two five-lens cameras were combined. By using them in tandem and rotating them by 45" relatively to each other, a ten-lens camera was produced, covering an octagonal ground area, with a total angle of view of 140". Similar designs have been evolved in other countries. In all of them, however, a number of difficulties have arisen, quite apart from their large weight and high cost. Because of their complex mechanism, numerous shutters and magazines, and the high precision with which these parts must be interadjusted and synchronized, these cameras are far from dependable. Moreover, a multilens camera by itself does not yet constitute a complete outfit for producing pictures suitable for photogrammetric survey. Because all the component pictures, except the central one, are obliques, it is always necessary to employ rectifying apparatus which transforms the marginal views to the perspective of the central one. In multilens cameras with many individual magazines, it is not convenient to

Jan 1, 1941

By A. W. Furbank

In reviewing the aerial cameras produced in different countries, it becomes apparent that in nearly all of them an attempt has been made to secure the greatest possible angle of view. This angle, of course, is determined by the objective. The objectives most commonly in use in aerial cameras have a maximum angle of 65". The objective developed for this new Zeiss camera combines freedom from distortion and brilliant definition, with an angle of 95". Aerial mapping, it is claimed, has been placed on a different economic basis, and new possibilities presented, particularly in connection with automatic stereoscopic plotting instruments, to which some short references are made. One way of enlarging the angle of view is to couple several instruments with their axes convergent, thereby producing a multilens camera. Typical of cameras of this sort in the United States is the Bagley four-lens camera, which later was developed into the five-lens camera (T3-A) of the U. S. Air Corps. More recently, in order to get away from the unfavorable Maltese cross image field of the five-lens camera, and to obtain a more practical form, two five-lens cameras were combined. By using them in tandem and rotating them by 45" relatively to each other, a ten-lens camera was produced, covering an octagonal ground area, with a total angle of view of 140". Similar designs have been evolved in other countries. In all of them, however, a number of difficulties have arisen, quite apart from their large weight and high cost. Because of their complex mechanism, numerous shutters and magazines, and the high precision with which these parts must be interadjusted and synchronized, these cameras are far from dependable. Moreover, a multilens camera by itself does not yet constitute a complete outfit for producing pictures suitable for photogrammetric survey. Because all the component pictures, except the central one, are obliques, it is always necessary to employ rectifying apparatus which transforms the marginal views to the perspective of the central one. In multilens cameras with many individual magazines, it is not convenient to

Jan 1, 1941

By M. Gell, G. R. Leveran

The high- and low-cycle fatigue properties of the nickel-base superalloy, Mar-MBOO, in columnar-grained and single-crystal forms were determined at room temperature. It was found that the fatigue lives of these materials were greatly affected by the size of preexisting cracks in MC-type carbides contained in the micro structure. Most of the data falls on two curves given by: (zN)'/A€= K, where Nf is the number of cycles to failure, Af is the total strain range, and K is a function of carbide size. No difference was observed in the fatigue behavior of the columnar-grained and single-crystal materials for the same MC carbide size. Matrix slip and crack initiation occurred at precracked MC carbides and, to a lesser extent, at micropores. Fatigue crack propagation was mainly in the Stage I mode, i.e., on cry stallo graPhic slip planes. The Stage I fracture in these materials was unusual in that distinct features were observed on the fracture surfaces. In high-cycle fatigue, these features resembled those commonly observed on the cleavage fracture surfaces of bcc and hcp materials. Yet, in this study, the cracks propagated slowly in a cyclic manner. In low-cycle fatigue, the Stage I facets contained equiaxed dimples, similar to those observed on the tensile fracture surfaces of ductile materials. These observations indicate that both local normal and shear stresses are involved in these Stage I fractures. A model is proposed to explain these results based on the weakening of the cohesive energy of the active slip planes by reversed shear deformation and the fracture of the bonds across the weakened planes by the local normal stress. RECENT developments in casting technology have produced cast nickel-base superalloys in columnar -grained and single-crystal forms.1'2 The tensile and creep properties of the nickel-base superalloy, Mar-M200, cast in these forms have been shown to be superior to the corresponding properties of the conventionally cast polycrystalline material.lp2 This improvement in properties results, in part, from the elimination of grain boundaries in the single crystals and the alignment of the grain boundaries parallel to the stress axis in the columnar-grained castings. As part of a program to evaluate the fatigue properties of nickel-base superalloys cast in single-crystal and columnar-grained forms, a study has been made of the cyclic deformation and fracture of Mar-M2OO at room temperature. M. fiFl I .hininr Mpmher AIMF ic ^pninr Rocoarrh Accn^iata anH I) EXPERIMENTAL PROCEDURE The composition range of Mar-Ma00 in weight percent is: 8 to 10 Cr, 9 to 11 Co, 11.5 to 13.5 W, 0.75 to 1.25 Cb, 1.75 to 2.25 Ti, 4.75 to 5.25 Al, 0.01 to 0.02 B, 0.03 to 0.08 Zr, 0.07 to 0.12 C, bal. Ni. All of the castings met the above specifications. The castings were solutionized for 1 to 4 hr at 2250°F followed by aging at 1600°F for 32 hr which resulted in a 0.2 pct offset yield stress of 150,000 psi at room temperature. The microstructure of the material consisted of cuboidal, coherent particles of ordered, fcc Ni3(A1,Ti) (commonly designated y'), approximately 0.3 p on edge, distributed in an fcc y solid-solution matrix. MC carbides together with shrinkage and gas micropores were also distributed throughout the materials. The MC carbides and micropores were located preferentially in the interdendritic interstices, as well as in the grain boundaries in the columnar-grained castings. The (100) direction of all the single crystals and the common (100) axis of the grains in the columnar materials were aligned within about 5 deg of the specimen axis. Fatigue testing was carried out in the high-cycle (HCF) and low-cycle (LCF) fatigue regions, with the major difference being gross yielding of the specimen occurred during the first cycle in the LCF region. This division also corresponded with the more usual one in which the life of a specimen in LCF is less than lo4 cycles and that in HCF is greater than lo4 cycles. The designs of the high-cycle fatigue and low-cycle fatigue specimens are shown in Figs. l(a) and (c), respectively. The gage sections of both HCF and LCF specimens were electropolished prior to testing. The HCF specimens were tested in an MTS, closed-loop, hydraulic fatigue machine at 10 cps in air. The specimens were cycled between a tensile stress of 5000 psi and a maximum tensile stress which ranged from 35,000 to 125,000 psi, Fig. l(b). The LCF specimens were cycled under strain control from zero to a maximum tensile strain, Fig. l(d), in a Wiedemann-Baldwin testing machine. The experimental procedure has been described elsewhere.3'4 Both HCF and LCF tests were interrupted periodically in order to replicate the development of slip and cracking at the specimen surface. This was accomplished by placing plastic replicating tape around the gage section of the specimen while the specimen was in the mahine. The size of the MC carbides for all specimens was measured on a polished longitudinal section through the gage section after fatigue testing. The method of measurement consisted of carefully scanning the entire polished section in order to locate the largest MC carbides. Photographs were then taken of the six longest carbides oriented approximately normal to the

Jan 1, 1969

By Hugh P. Nicholson

IN view of the many articles that have been written on the proper classification of mining systems without so far having produced any particular tangible results it might seem that the subject is hopeless of solution. I do not believe that is so, and my intention in contributing the following outline is to present a slightly different viewpoint. Too much attention is often focused on unnecessary details and not enough on general principles. Too much attention and emphasis is often given to the system employed at one particular mine or in one particular district. In addition, names that are entirely misleading are applied to mining systems, and their adoption by the coming generation perpetuates a condition that needs clarification badly. The following classification is the result of several years of practical experience in mining and also several years' practice in teaching the same subject. It therefore represents a broad picture of the entire field of mining systems from the viewpoint of the miner as well as the teacher. It seems that the difficulty in the past has been in reconciling these two viewpoints. The need of such a reconciliation requires no explanation.

Jan 1, 1934

By C. B. Alcock, R. A. Oriani

Some simple models of solutions are described; these include the regular solution, the subregular solution, and the quasichemical model. The assunzption underlying these models, the physical signzficance thereof, and the experimental manifestations are discussed. Examples are presented from the fields of liquid and solid metallic solutions, liquid slags, mattes, liquid and solid ionic solutions, and mixed carbides to show under what conditions and for which systems these solution models are fair descriptions. The deviations of real solutions from the models are of theoretical interest. Some such deviations, both for dilute and for concentrated solutions, arc pointed out and their Physical sigtzzficance discussed. DURING the past half century there has been a gradual accumulation of thermodynamic data for systems of interest to the metallurgist. There remain many gaps in the data, however, and the metallurgist must often face the problem of estimation of thermodynamic quantities where measured values do not exist. One might hope that the experimental progress would be matched by theoretical advances which would make such estimations possible with a high degree of confidence. However, theoretical progress has been disappointingly slow even for the simplest kinds of solutions, and since the multicomponent systems in which the metallurgist is interested are very complex, one cannot expect theory to be of much help to the metallurgist. In this situation, therefore, it seems worthwhile to examine some simple models of solutions from two points of view: firstly, to see if such crude models represent the thermodynamic facts in as many types of solutions as possible sufficiently well for the needs of the metallurgist, and secondly to see what the deviations from such models show to be important for consideration by theorists. BOND ENERGY MODELS OF SOLUTIONS The simple models that we will examine from these points of view may be termed statistical models, in that they are concerned with the thermodynamic consequences of some simple assumptions about the energy of an assembly of atoms, molecules, or ions, and do not inquire into the physical basis of the interaction. The underlying assumption of these models is that the energy of an assembly of molecules (by which we include also atoms or ions) is given by the sum over all interaction energies of molecules taken two at a time; we will discuss only those models in which the pairwise interactions are restricted to those between nearest neighbors. Thus, in a pure substance of bond energy EAA, the internal energy (with respect to some specific reference state) will be expressed as NAA EAA where NAA is the number of nearest-neighbor pairs. A solution of molecules A and B will be characterized by NAA EAA + NBB EBB + NAB EAB where the Eij represent the bond energies of the nearest-neighbor i-j pairs. If one assumes that the EAA and EBB are the same in the pure components as in the solution, and that the coordination numbers in the two pure substances and in the solution are the same, then the energy of the solution with respect to the pure components (i.e., the energy of solution) is a function of the following linear combination of the bond energies: EAB - 1/2(EAA +EBB) = w. The thermodynamically ideal solution is defined as one in which the activity of each component is equal to the mole fraction of that component at all concentrations and all temperatures. It follows that

Jan 1, 1962