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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' 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 G. A. Hellstrand

IN 1915, H. A. Guess, Vice President of American Smelting & Refining Co., in charge of its Mining Department, learned that the Anglo-New-foundland Development Co., Ltd., a pulpwood and paper-mill enterprise, had found upon its large concession in Newfoundland, and had opened up by shaft to the third level and some drifting, a lenticular orebody indicat-ing about 100,000 tons, as an extremely fine-grained sulfide ore, averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Cu, 10 per cent Pb, 18 per cent Zn; and that having sent parcels of this ore to Minerals Separation, Ltd., and various other metallurgical testing concerns without obtaining any success in commercial separations thereon, had discontinued work thereon and let the workings fill. Mr. Guess wrote to the general manager of that company and obtained a few hundred pounds of the typical ore, which he sent to his company's metallurgical testing laboratory at Flat River, Mo., outlining various flotation tests desired thereon, in an endeavor to obtain separation into a commercial lead concentrate and a zinc concentrate. But the art of flotation had not then progressed far enough to treat such ore, the galena and zinc blende being so fine grained that grinding to about 300 mesh was required to release the mineral particles in their gangue. Mr. Guess had flotation and other tests continued upon this ore from time to time with whatever new reagents and flotation devices were evolved as time went on, and finally, in 1925, he succeeded in effecting in his company's testing plant, then at Wallace, Idaho, separations into lead concentrates and zinc concentrates of satisfactory commercial grade. Mr. Guess then proceeded to unwater, examine and sample the property and made with the owners a partnership operating agreement upon the mine itself and a considerable area surrounding it, and in the early summer of 1926 began to prospect for additional orebodies, utilizing for such prospecting geophysical methods, under the direction of Hans Lundberg, methods which up to that time had been little used in mining in the western hemisphere.. This geophysical work found two large flat-lying orebodies of a type precisely similar to the smaller body of the original discovery. The larger orebody, some 3500 ft. west of the original

Jan 1, 1934

By Guy Ruggles

IN this paper the authors aim to chronicle the experience and salient points brought out in changing flotation reagents at a concentrator which had probably been using a minimum amount of oil at a minimum cost per ton, to a more complicated system requiring a partial chemical control. The original oils were coal tar and pine oil. The new reagents are line, xanthate and pine oil. It was found that there were no insur-mountable difficulties and eventually the cost of the new reagents per ton of ore proved to be very little more than that of the old. LIME PLANT When the question of handling lime came up there were two propositions open: (1) to handle the lime dry; (2) to handle it wet in the form of an emulsion. Granting that a dry lime feeder would function properly, delivering lime uniformly, the chief objection was the dust that would be raised when these feeders were being charged or operated, as the only possible location was on a gallery beneath which men were working. With this objection the handling of lime as an emulsion seemed to he the better scheme. The lime plant which was first installed was for experimental work on one section. This was gradually changed and developed until it was of sufficient size to accommodate 20 sections. The various changes will not be discussed and the following description deals only with the fully developed plant. Crude as it is, and perhaps somewhat expensive to operate, the lime-handling plant has been quite successful. Much has been learned which will pave the way for a better installation in the future.

Jan 1, 1927

Mining and Metallurgy of Lead and Zinc, AIME Vol. 121, edited by Dr. C. R. Hayward in 1936, remains a document of importance today even though 34 years have passed in the meantime. Since nothing in this world seems to be permanent, however, and progress brings new and better ways to do things, a two-volume set has just been published to bring the state of the art of 1936 up to date. This two-volume set, Mining and Concentrating of Lead and Zinc and Extractive Metallurgy of Lead and zinc, incorporates the papers to be presented during the Proceedings of the 1970 World Symposium on the Mining and Metallurgy of Lead and Zinc. The Symposium is being held October 20-24, 1970, in St. Louis, a site near to the famous Lead Belt of southeast Missouri. Some eighty papers are bound in these two volumes covering exploration, geology, mining, concentrating, roasting, smelting, electrolytic processing, residue fuming, refining, etc. All of this is laced with data on tonnages, processes, assays and efficiencies obtained, and the man-hours and equipment needed to achieve these performances.

Jan 1, 1970

The following list comprises the names of those persons who became members during the period May 10, 1916, to June 10, 1916: ARCHIBALD, JOHN CHRISTIE, Min. Engr., Supt. of Cyanide Plant, Guanajuato Reduction Mines, Guanajuato, Mex. BRUNEL, FRANK P., Cons. Min. Engr Mitchell & Brunel, Ajo, Ariz. CALVERT, WILLIAM ROBERT, Cons. Geol. ...225 Kearns Bldg., Salt Lake City, Utah. CHAMPION, J. R., Supt The Yak Mining, Milling & Tunnel Co., Leadville, Colo. CHARLES, LAVERN JOHN, Construction Engr., Elephant Butte Dam, Elephant Butte, N. M. CHASTEL, ANDRE, Min. Engr., Societe Miniere & Metallurgique de Penarroya, 12, Place Vendome, Paris, France. CHRISTIE, WALLACE H., Vice-Pres. and Mgr., Alt. Bert Gold Dredging Co., 604 Mission St., San Francisco, Cal. CLARK, RONALD ..Hardinge Conical Mill Co., 120 Broadway, New York, N. Y.

Jan 7, 1916

By W. H. Bassett

A 10-year, sea-water, corrosion test of tubes of several copper alloys has shown that many alloys withstood attack by solution, pitting, and dezinkification; a 1-year, salt-spray test of sheet-metal specimens of the same composition showed the same results. THE late J. P. Sparrow, chief operating engineer of the New York Edison Co., carried out a series of practical tests on condenser tubes of several copper alloys and reported on the results to the Association of Edison Illuminating Companies at its meeting in' September, 1913. In the preparation of these tubes the senior author had the pleasure of cooperating. Copper-zinc alloys in the proportions of 60-40, 70-30, 80-20, 90-10, and Admiralty metal, which is in effect 70-30 with 1 per cent. of tin, were tried. Monel metal and several copper-nickel alloys, and 8, 5, and 3 per cent. aluminum bronze were also tried. At the time of this report, the aluminum bronze had been in service for 4 1/2 years and seemed to be giving especially good results but later it began to fail and showed no substantial improvement over Admiralty metal. Monel metal was unsatisfactory and the nickel alloys apparently did not give better service than the Admiralty alloy. Previous to the publication of the report, and after considerable discussion, it was agreed that a test where tubes of different kinds could be under laboratory observation would be advisable, so the apparatus described here was set up in The American Brass Co.'s Waterbury Laboratory. This was fitted with tubes of copper, brass, bronze, nickel silver, cupro-nickel and other alloys, and the test started Oct. 11, 1912. Salt water from East River, New York harbor, was barrelled and transported to the laboratory for the test. A fresh supply, completely replacing the water in service, was obtained at the end of each six months period.

Jan 1, 1925

By C. R. McEwen

This paper presents a technique for calculating the original amount of hydrocarbon in place in a petroleum reservoir, and for determining the constants characterizing the aquifer performance, based on pressure-production data. A method for doing this based on a least-squares line-fitting computationwus proposed by vanEverdingen,Timmerman andMcMahon in 1953. We found that their method would not work when there is error in the reservoir pressure data — even moderate error. The technique presented here appears to give reasonable answers when pressure data are uncertain to the degree expected in reservoir pressure determinations. The major change introduced in the present analysis is to limit the least-squares line-fitting to yield only one constant— the amount of hydrocarbon in place. The water-influx constant is then taken as proportional to the oil (or gas) in place. The constant of proportionality can be computed from estimates of effective compressibility and reservoir water saturation. It is also pointed out that the commonly used least-squares analysis assumes all of the uncertainty to be in the dependent variable. The material balance should be arranged so that this condition is fulfilled if correct inferences are to be made from statistical calculations. Examples are shown of the application of the new technique to gas reservoirs—both hypothetical and real—and to the oil-reservoir example of van Ever-dingen, Timmerman and McMahon. INTRODUCTION The amount of hydrocarbon originally in place in a petroleum resenroir can be estimated by means of the material-balance calculation. Simultaneous observations of pressure and amounts of produced fluids are required, together with the PVT data applicable to the reservoir fluids. If water encroachment is occurring, it is desirable to try to infer the behavior of the aquifer, as well as the original hydrocarbon in place, from the pressure-production data. This imposes additional demands on the method of calculation, and uncertainty in the data can result in large uncertainty in the answer. In addition, if the size of a gas cap is to be established, the whole problem becomes indeterminate, as pointed out by Woods and Muskat.1 Brownscombe and Collins2 simulated a gas reservoir and its aquifer on a reservoir analyzer and derived quantitative information on the effect of uncertainty in pressure and aquifer permeability on computed gas in place. Among the various techniques of estimating the performance of an aquifer, the method of van Ever-dingen and Hurst? based on compressible flow theory, seems to have been the most generally successful (see Ref. 4, for example). In this paper we shall confine ourselves to their representation of the aquifer. In 1953,' van Everdingen, Timmerman and McMahon5 introduced a statistical technique for deriving the amount of oil originally in place and the parameters which describe the aquifer. (We shall refer to this technique as the "VTM method'', as suggested by Mueller.6) Their example reservoir had no gas cap. It has been our experience that the VTM method gives a reasonable answer when the data are very accurate, but that inaccuracy (particularly in pressure) can cause the method to break down. The effect was first observed in gas reservoirs, but has since been seen in oil reservoirs also. In this paper we present another statistical method which has been successful in achieving a reasonable answer where the VTM method has failed. In the new method, one less parameter is derived from material-balance computations. It is assumed that values can be established for effective compressibility in the aquifer and reservoir water saturation independently of the material-balance calculation. The water-influx constant can then be obtained from these data and the quantity of hydrocarbon in place.

By Richard Akerman

At the International Sessions of the Iron and Steel Institute of Great Britain, the American Institute of Mining Engineers and the Verein Deutscher EisenhUttenleute, held in Allegheny City, Pa., in October, 1890, Sir James Kitson, then President of the Iron and Steel Institute, presented an account by Sir Henry Bessemer of the origin of the process which bears his name.? The paper graplhically told how, after the first successes immediately following the first reports given at Cheltenham of the new process, there rapidly succceded such obstacles and difficulties in its practical application, that the whole matter was nearly abandoned in 1858. Suddenly, however, the situation changed, so that at length it became possible

Jan 1, 1894

By K. Thirumalai, D. P. Schlick

Longwall Technology has a potential of resulting in safety and productivity improvements of U.S. underground coal mining similar to those experienced by the introduction of continuous miner systems. The study presents a comprehensive national evaluation of longwall technology to assess the potential of longwalls to improve health and safety and coal productivity. The study was conducted by the authors during the spring of 1980 as part of MSHA New Technology Coordination activities and with a view to examine the factors that may limit the acceptance of longwall technology in the U.S. coal mining operations. The study points out areas where adjustments need to be made in MSHA regulations and enforcement to help Longwalls. A two-entry longwall system appears to offer a practical method of improving underground coal productivity and safety. Applying regulations that are primarily designed for room and pillar methods to longwall mining, in some instances, reduces the effectiveness and productivity benefits feasible by new technology application. Controlling dust is the single predominant problem in the design and operation of longwalls in the United States. The results of this study points out a need for a coordinated program between government and industries on dust control technologies for examining acceptable technological options to control dust in longwalls without restraining the production capability of the system.

Jan 1, 1981

By H. B. Pulsifer

The unprecedented high price of zinc ore prevailing through the early months of 1915 caused great activity in the Joplin district of Missouri. The Media mill is conspicuous as one of the first of the new "big mills" of the district. The mill was built over a mine previously worked but abandoned in 1912 because of the leanness of the ore and the large quantity of water encountered. The ore prices prevailing—$100 a ton in June, 1915, as against $50 in 1912-—favored the new undertaking. The mill was designed for good recovery so that it might operate in times of depression. In design and equipment, the mill is exclusively local in conception and construction. Former Exploitation The tract of land is a part of the large Guinn holdings; 70 acres are comprised in this particular lot, which is situated just a mile north of the center of Webb City on the Alba line of the Southwest Missouri Electric Railway. The ore lies 242 ft. below the surface at the top of the knoll which is surrounded by the well known properties: Black Cat, Ground Floor, Florence, Hurry-Up, Electrical, and Mercantile. Since the abandonment, in 1913, of the Yellow Dog a bit farther to the north, the Black Cat, Ground Floor, and Florence workings had been flooded. However, as there was no cut through from this side into the area it was proposed to exploit, it was thought that moderate pumping facilities would take care of the water. Three shafts had already been sunk to the ore horizon during the previous operations; the ground was connected by wide drifts and possibly 10 acres mined out, principally about the two southerly shafts which at surface are 8 and 13 ft. lower, respectively, than the collar of the shaft at which the new mill was built. The former mill on the lease was known as the Bohemian Girl. This mill, built in 1910, was removed after some 3 years' work. A head frame and hopper still existed at the middle shaft, sometimes known as the lower Hold Out shaft, but at the most northerly

Jan 1, 1918

By N. N. Clark

Pachuca tanks are used widely as reactors for treating gold slimes, and for alumina digestion and uranium leaching. In some designs, slurry mixing in the tank is achieved by introducing air at the base of a draft tube, which is the full height of the tank. A buoyant air-slurry mixture rises in the draft tube and is discharged at the top. The slurry flows back through the bulk of the tank volume. Little information is available to predict the relationship between slurry flow rate in the draft tube, and the volume of air added at the base of the tube. Most current designs are based on the energy balance proposed by Lamont 25 years ago. Recent two-phase flow theory is used to develop a momentum balance for the flow in the draft tube, and a new, accurate design equation is derived. Bubble slip, frictional (wall) losses, entrance losses, and acceleration effects all contribute to the pressure gradient in the draft tube. None of these factors may be neglected under typical operating conditions. The new design equation accounts for all of these factors, and finds good agreement with Lamont's experimental example. Also, the new equation demonstrates that it is uneconomical to operate the draft tube with high airflow rates.

Jan 1, 1985

By H. A. Schlesinger

Various studies have estimated that for the next few decades, about half of all new power plants will be nuclear. The other half will be fueled with coal. Pending legislation on air pollution control would require all new coal-fueled power plants to install stack gas scrubbers or other technology to reduce sulfur oxide (SO,) emissions. These regulations would require flue gas desulfurization (FGD) or other technology for SO, reduction even on lower sulfur western coals. Among the options for FGD are single or dual alkali throw away processes using lime or limestone as the major reagent. These processes are currently more economically attractive than recovery processes, such as magnesium oxide and Wellman- Lord, that produce a salable product such as sulfur or sulfuric acid. One of the major problem areas with the throw away processes is disposal of the thrown away solid wastes, primarily calcium sulfite (CaSO3) and calcium sulfate (CaS04). Coal ash also must be disposed of, even if SOx reduction is not required. This paper addresses the alternatives for handling and disposal of throw away lime, limestone, and dual alkali process solid wastes. Advantages, disadvantages, and the economics of various methods are discussed. Both large central station power plants (500-1000 MW capacity) and smaller industrial power plants (up to 100 MW capacity) are considered. High sulfur eastern coals (53% S) and lower sulfur (3 1% S) western coals are considered.

Jan 1, 1981

By T. F. Witherbee

On .the 22d of November, 1879, white, iron unexpectedly ap peared while working the Cedar Point Furnace, Port Henry, N Y., on the following burden, calculated to turn out mill and foundry iron: Anthracite coal,. ., .. .. 8000 pounds. Connellsville coke,. ..1500 " Total,..4500 " Old Bed ore,........ 3750 " New Bed fine ore,. ..2000. " New Bed chunk ore,. .. 1000 " Kearnev hematite ore,.750 " Total,..... 7500 " Magnesian limestone,. 1665 " Common limestone,. ...835 " Total,........ 2500 " The production per week since making mill iron-—from September 1st, 1879, to date, seven weeks—was 412 gross tons. Ore was not immediately taken off, as nothing serious was looked for. The iron for the next week graded from No. 4 to white, and in six days the make was 2741/2 tons. At 10 p.m., Friday, the 28th, a slip of -14 feet occurred, and on Saturday, at 5 A.M., another of 3 feet on the south side and 7 feet on the north side took place. At this time it was found that the south side had been hanging for over a week—a fact which had not been reported. Throwing off the wind, to produce slips and reduce pressure, had been tried with no effect. The stock, as seen through the tuyeres, seemed to consist almost entirely of coal, with just enough infusible cinder to cement it into a mass through which the blast could not be forced. At 3.50 A.M., Sunday, the 30th, the first cinder seen in seventeen hours came into tuyeres Nos. 1, 2, 3, and 6. At 9.30 A.M. No. 3 was taken out to see if the stock

Jan 1, 1881

By N. F. Schulz, H. A. Lex, J. D. Zetterstrom

A green ball of iron ore faces many perils from the time it is formed until it finally emerges from the pelletizing furnace as a hardened pellet. For instance, if the rate of heat transfer into a ball is sufficient to produce vapor from either the free or combined water more rapidly than it can escape at a tolerable pressure, the ball may split, spall, or even explode, a failure commonly known as decrepitation. To avoid such failures, one must either limit the rate of heat transfer during the drying and preheating stages, at the expense of production rates, or improve the decrepitation resistance of the green balls. The latter remedy may often be accomplished through changes in ore preparation, balling procedures, or the judicious use of binders or other additives. INTRODUCTION Pelletization has become established as an especially desirable method for the agglomeration of fine taconite concentrates and it promises to be equally satisfactory for improving the physical structures of certain natural ores. A high-quality pelletized iron ore consists of uniformly sized spheres, usually about 1/2-in. diam, which are strong enough to resist abrasion and breakage during handling and which reduce well without disintegration in the blast furnace. The unfired agglomerates, "green balls", are subject to several destructive effects that must be avoided or minimized if a high-quality product is to be obtained by pelletization. Among these are abrasion and impact deformation or breakage during handling of the wet green balls, deformation and breakage by compressive forces in the bed of ore in the pel-letizing furnace, decrepitation during drying and preheating, wind erosion, and radial cracking at firing temperatures. Moisture condensation from the warm saturated gases downstream from the drying zone on wet, cool balls may cause bed collapse if it becomes excessive. Decrepitation is defined as the sudden disintegration of green balls, usually with an audible pop, that occurs when they are heated too rapidly during the drying or preheating stages of the pelletization process. The extent of ball disintegration may vary from merely splitting off a small fragment to almost total disintegration into the original ore particles making up the ball. Such ball destruction results in a decreased yield of pellets, and the fragments, which also tend to interfere by obstructing the gas flow through the bed, must eventually be screened from the fired product and recycled. The closely related type of ball failure that sometimes occurs during the high temperature firing stage, resulting in radial cracks without fragmentation, was not considered to be decrepitation for the purpose of this investigation. Failure by decrepitation is not usually a serious problem in the pelletization of taconite concentrates. The problem is significant, however, in the pelletization of some natural ores, especially those containing hydrous iron oxides. In some instances, economicd production rates cannot be maintained if the drying and preheating rates are slowed down enough to avoid decrepitation. OBJECTIVES This investigation was undertaken to: (1) Develop a practical laboratory means for quantitatively measuring the tendency for green balls to decrepitate in iron ore pelletizing furnaces, and (2) Investigate the causes and cures of ball decrepitation. MATERIALS Two iron ores were used in the work reported here: a taconite concentrate at 90% minus 325 mesh, containing 65.0% Fe, 8.4% SiO2, and no loss-on-ignition; and a crude oxidized ore at 54% minus 325 mesh, containing 59.1% Fe, 3.6% SiO2, 1.1% A12O3, and 9.5% loss-on-ignition. For a special test of effect of particle size distribution on decrepitation, two other

Jan 1, 1967

By W. S. McCain, B. A. Wilcox, A. H. Clauer

The creep and creep-fracture behavior of a Ni-200-2Th0, alloy has been studied over the temperature range 816° to 1038°C and stress range 4000 to 19,000 psi Specimens having their axes either parallel or transverse to the final sheet-rolling direction were tested in air, and the apparent activation energy for creep was found to be 92 kcal per mole, regardless of specinien orientation. The stress dependence 01- the steady-state creep rate, was satisfied by where n depended on orientation; n = 9.7 for rrzaterial transverse to the rolling direction and n = 24.3 for material parallel to the rolling direction. In the latter case, the relation was also valid. The rupture strength of material parallel to the rolling direction was -1.5 times gveater than the transverse rupture strength. Several tests in vacuum revealed that here the creep rate was higher and rupture life lower than for comparable tests in air. THERE is an increased interest today in producing improved dispersion-hardened alloys for high-temperature structural applications. This had led various materials designers to modify existing alloys, such as thoriated nickel. One system that has received considerable attention is based on chromium additions to Ni-ThO2, with the obvious motive of improving the oxidation resistance. Another effect of chromium is that of lowering the stacking-fault energy, y, of nickel. For example, the addition of 30 wt pct Cr decreases y from -225 erg per sq cm for pure nickel1 to -70 erg per sq cm.' This decrease in y could have several effects on the deformation behavior. There is some evidence that cross slip of dislocations around Tho2 particles is a mechanism of tensile3 and creep4 deformation in TD Nickel (Ni + 2 vol pct ThO2) at temperatures below 0.5 the absolute melting point of nickel, T,. A decrease in ? by chromium additions should increase the difficulty of cross slip. Also it has been suggested that the high-temperature (T > 0.5Tm) rate-controlling creep process in "recrystallized" Ni-Tho2 alloys is the climb of edge dislocations over Tho2 particles.5 According to weertman6 a decrease in the stacking-fault energy should decrease the dislocation climb velocity resulting in a decreased steady-state creep rate. Thus, chromium additions to recrystallized Ni-Tho2 alloys would be expected to decrease the creep rate, all other conditions being constant. However, a difficulty arises when the stacking-fault concept is applied to high-temperature creep of dispersion-strengthened metals which are produced on a commercial or semicommercial scale. This occurs because the materials are processed so that they have a high-stored energy of cold work, and the other substructural effects could obscure any influence of stacking-fault energy per se. An example of an alloy with a high stored energy of cold work is TD Nickel bar. This material has a fibrous grain structure (1 I diam by 10 to 15 p long), and the structure is stabilized by the ThO2 particles. Annealing at high temperatures, e.g., 3 hr at 1300°C, causes no recrystallization or grain growth.4 Previous work by the authors4 showed that the high -temperature creep behavior of TD Nickel could not be related to any simple dislocation theory of creep, and this probably was associated with the complex initial structure of the material.

Jan 1, 1968

By Clarence Zener

Contents Page General Principles................................................................. 551 Equilibrium Diagrams......................................................... 551 Nucleation................................................................... 553 Kinetics of Phase-boundary Propagation......................................... 553 Kinetics of Growth of New Phase............................................... 556 Spheroidization............................................................... 560 Pure Iron-carbon System........................................................... 561 Formation of Pearlite.......................................................... 561 Interlamellar Spacing........................................................ 562 Pearlite C-curve............................................................. 563 Bainite Formation............................................................. 565 Formation of Martensite....................................................... 570 Loss of Tetragonality of Martensite.............................................. 570 Effect of Alloys upon Decomposition of Austenite..................................... 572 Pearlite...................................................................... 572 Bainite and Martensite......................................................... 574 Time-temperature-transformation Curves............................................. 576 Appendix A............................................................. ......... 579 Appendix B....................................................................... 580 Appendix C....................................................................... 580 The present investigation started in an attempt to understand certain details of the decomposition of austenite, and of the effect of alloying elements thereon. As the investigation proceeded it became apparent that not only these details, but all the general features of austenite decomposition, could be understood in terms of fundamental physical principles. Since the direct applicability of these physical principles has not been previously recognized, it was decided to incorporate the original results of the investigation into a review of the general subject of the kinetics of austenite decomposition. This review constitutes the present article. An extended summary of the results is given on pages 576 to 579. This article, which deals with the kinetics of phase transformations, may appropriately be considered as a sequel to two recent articles1,2 from this laboratory on the equilibrium relations in medium alloy steels.

Jan 1, 1947

By Clarence Zener

Contents Page General Principles................................................................. 551 Equilibrium Diagrams......................................................... 551 Nucleation................................................................... 553 Kinetics of Phase-boundary Propagation......................................... 553 Kinetics of Growth of New Phase............................................... 556 Spheroidization............................................................... 560 Pure Iron-carbon System........................................................... 561 Formation of Pearlite.......................................................... 561 Interlamellar Spacing........................................................ 562 Pearlite C-curve............................................................. 563 Bainite Formation............................................................. 565 Formation of Martensite....................................................... 570 Loss of Tetragonality of Martensite.............................................. 570 Effect of Alloys upon Decomposition of Austenite..................................... 572 Pearlite...................................................................... 572 Bainite and Martensite......................................................... 574 Time-temperature-transformation Curves............................................. 576 Appendix A............................................................. ......... 579 Appendix B....................................................................... 580 Appendix C....................................................................... 580 The present investigation started in an attempt to understand certain details of the decomposition of austenite, and of the effect of alloying elements thereon. As the investigation proceeded it became apparent that not only these details, but all the general features of austenite decomposition, could be understood in terms of fundamental physical principles. Since the direct applicability of these physical principles has not been previously recognized, it was decided to incorporate the original results of the investigation into a review of the general subject of the kinetics of austenite decomposition. This review constitutes the present article. An extended summary of the results is given on pages 576 to 579. This article, which deals with the kinetics of phase transformations, may appropriately be considered as a sequel to two recent articles1,2 from this laboratory on the equilibrium relations in medium alloy steels.

Jan 1, 1947

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By Bhudeo N. Sinha, Paul Dean Proctor

Heavy metal contents in stream waters, sediments, and selected aquatic algae were determined for the upper Meramec River basin, Missouri, of 3905 km2 (1508 sq mi) area and site of the proposed and controversial Meramec dam and reservoir. Six distinct drainage areas within the basin are: (1) a lightly industrialized and farm area, (2) a primitive forested- ranch area, (3) an area which includes the Northern New Lead Belt, (4) the westward drainage of an old and extensive barite mining area, (5) the main trunk of the Meramec River, and (6) short north-divide tributaries of the Meramec River. Lower Paleozoic sediments rest nonconformably upon eroded and hilly Precambrian igneous basement. This locally rises as major inliers and also makes up the St. Francois Mountains to the east. Major lead, and lesser zinc, copper, cobalt, and nickel mineralization occurs in the buried Cambrian Bonneterre dolomite. Residual barite is present along the eastern fringe of the basin and is derived from the Potosi formation. Some 62 water samples, active stream sediments (AS), bank samples (BS), and 11 selected aquatic algae samples were collected in the various drainage areas and analyzed for copper, lead, zinc, cadmium, nickel, arsenic, and mercury contents. Heavy metals in water have a maximum range of 1-120 ppb (parts per billion), and this for zinc. The AS and BS sediments have orders of magnitude greater acid leachable metal contents in the -80 mesh fraction, with lead hawing the greatest range of 11-1028 ppm. Heavy metal content of stream-algae approaches that of the sediments in which they grow. Most anomalous heavy metal accumulations occur near mining and milling activities and in the streams draining such areas. Significant distortions of the primary dispersion pattern militate against geochemical exploration for hidden ore zones, but do demonstrate the mining, milling, and smelting activities of man, and sporadic mineral occurrences in younger horizons.

Jan 1, 1980