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By T. Egleston

THE direct process for the manufacture of iron which is principally used in the United States, in New York and New Jersey, is called the Jersey forge, the Champlain forge, the Catalan forge, the Bloomary forge or fire, and sometimes a Forge fire. Dr. T. Sterry Hunt, who has discussed the process as applied to the beach sands of Canada as well as to ores, in the Report of the Canadian Geological Survey for 1867-69, has shown that the name of Catalan forge is incorrect, as this process in no way resembles the Catalan, but is really the old German bloomary modified by long use in this country. Dr. Hunt gives the probable history of the introduction of the process into the United States, and a series of historic citations of great interest relating to it. Not¬withstanding the improvements which have been made in the construction of the furnace and its greater output, the process to-day, in all its essential features, is carried out as Karsten described it. It should now be known as the American Bloomary. The name of Jersey or Champlain forge or fire is not sufficiently distinctive. The name of Bloomary, by which the process is usually distinguished, is objectionable, not because it is incorrect but because it is indefinite, as the Knobbling fires, which are a very slight modification of the Walloon process, for making blooms either from pig iron or by sinking scrap, are also called Bloomaries, and although Knobbling fires are only used in a few localities where charcoal pig is made, and special grades of charcoal-refined blooms are required, one does not, without an explanation, know whether the blooms are being manufactured from ore or pig. The name Forge fire is equally indefinite, as it might just as well apply to any of the five direct methods of making blooms which have been in use in Europe, but which have now mostly gone out of date. The Dame of American Bloomary, however, is the one which most completely describes it, and is the one least open to objection. The names of German, Jersey, and Champlain bloomary are too local, and these adjectives are thought unnecessary by those who use the process, and we shall not therefore describe it under any of these names, but as the American Bloomary process. * Read at the Montreal meeting, September, 1879.

Jan 1, 1880

By J. R. Long, E. T. Hayes, D. C. Root, R. S. Dean

THE U. S. Bureau of Mines has recently reported on the development of a process for preparing pure ductile titanium in substantial quantities' and on the physical properties that may be attained in the metal, when consolidated by powder metallurgy methods and fabricated by certain hot and cold-working procedures.2 The high physical properties (Table I), combined with excellent corrosion resistance and light weight, will lead no doubt to appropriate applications of the metal. In any application, methods of joining will be of considerable importance. The relatively high activity of the metal toward the common gases raises the question of weldability and conditions that might be required for successful welding. Since hydrogen, oxygen, and nitrogen embrittle the metal, it should be protected from these gases at elevated temperatures. This was demonstrated by a few preliminary trials of arc, gas, and resistance welding. In these trials only the resistance method proved to be immediately applicable. While atomic hydrogen welding of titanium may be successful in some instances, a considerable amount of development work will be required to prove its worth. In addition, it would be suited only to small assemblies that could be heated subsequently in a high vacuum to remove embrittling hydrogen. Heli-arc methods likewise would be limited to small assemblies, which could be completely protected by a helium atmosphere. It was quite apparent that titanium required more protection than was afforded by the normal flow of helium gas used for welding magnesium and aluminum. The hot metal is attacked by oxygen and nitrogen, and the rapid diffusion of the oxide into the metal prevents the formation of a protective coating and requires the helium atmosphere to be maintained until the weld has cooled nearly to room temperature. The preliminary work indicated that titanium could be successfully spot-welded without deterioration of the metal and that the microstructures of the welds were normal, exhibiting good bonding, and no oxidation. The high resistivity of titanium (53 microhms per cu. cm.) suggested that it would behave somewhat like stainless steel and allow considerable latitude in the several welding variables. The results reported here are intended to give a general picture of the effects of varying welding current, welding time, and tip pressure on single spot welds made on several different thicknesses of titanium sheet. The work was undertaken to demonstrate the feasibility of welding titanium rather than as an exhaustive study of spot welding. There are, therefore, a number of factors that will require further investigation to establish the specific controls required for actual applications.

Jan 1, 1946

By Joseph W. Leonard, T. S. Spicer

INTRODUCTION Reasons for Thermal Drying The continuing increase in the percentage of minus %-inch coal produced as a result of the increased use of mechanical mining methods has, over the years, tended to shift considerable portions of the work of producing saleable coal to the fine coal cleaning section of the preparation plant. Because a given weight of fine coal will contain substantially greater surface area than an equivalent weight of coarse coal, it follows that, when subjected to wet cleaning processes, the fines will absorb and retain consider- ably more moisture than coarser fractions. Increased moisture pickup in the finer sizes complicates fine coal cleaning since beneficiation may not be limited to the removal of ash and sulfur but often must be expanded to include the additional step of thermal drying to remove excessive moisture. Thus, water which provides the medium for cleaning fine coal is in itself detrimental and, like ash and sulfur, reduces coal quality. Removal of surface moisture by drying is done for one or more of the following 1 reasons: (1) To avoid freezing difficulties and to facilitate handling during shipment, storage and transfer to the points of use; (2) to maintain high pulverizer capacity; (3) to reduce heat loss due to evaporation of surface moisture from the coal in the burning process, thus increasing heating efficiency; (4) to improve the quality of coal used for special purposes, such as in the production of coke, briquettes, and chemicals; (5) to decrease transportation costs; and (6) to facilitate dry coal-cleaning processes. Because benefits to coal transportation and utilization are the most common reasons for thermal drying, the following sections will examine these areas in greater detail. Benefits to Transportation Initial benefits from drying are the reduction of shipping costs from the mine to the point of utilization since more coal can be concentrated into a given weight of product when worthless moisture is removed. Non- combustible~ such as water and mineral matter in railroad shipments of coal are billed the same as coal at $3.32 per ton, according to the recent average costs. Savings of 10 to 20 dollars from drying on the shipment cost of each 50 to 60 tons of coal contained in a typical railroad car is common. Savings on coal shipments from individual mines which result from coal drying can be expressed in terms of hundreds of thousands of dollars and more each year. For example, a reduction of shipping charges of only 5 percent on one million tons per year would mean a savings of 166,000

Jan 1, 1968

By T. Egleston

The direct process for the manufacture of iron which is principally used in the United States, in New York and New Jersey, is called the Jersey forge, the Champlain forge, the Catalan forge, the Bloomary forge or fire, and sometimes a Forge fire. Dr. T. Sterry Hunt, who has discussed the process as applied to the beach sands of Canada as well as to ores, in the Report of the Canadian Geological Survey for 1867-69, has shown that the name of Catalan forge is incorrect, as this process in no way resembles the Catalan, but is really the old German b1oomary modified by long use in this country. Dr. Hunt gives the probable history of the introduction of the process into the United States, and a series of historic citations of great interest relating to it. Notwithstanding the improvements which have been made in the constrnction of the furnace and its greater output, the process to-day, in all its essential features, is carried out as Karsten described it. It should now be known as the American Bloomary. The name of Jersey or Champlain forge or fire is not sufficiently distinctive. The name of Bloomary, by which the process is usually distinguished, is objectionable, not because it is incorrect but because it is indefinite, as the Knobbling fires, which are a very slight modification of the Walloon process, for making blooms either from pig iron or by sinking scrap, are also called Bloomaries, and although Knobbling fires are only used in a few localities where charcoal pig is made, and special grades of charcoal-refined blooms are required, one does not, without an explanation, know whether the blooms are being manufactured from ore or pig. The name Forge fire is equally indefinite, as it might just as well apply to any of the five direct methods of making blooms which have been in use in Europe, but which have now mostly gone out of date. The name of American Bloomary, however, is the one which most completely describes it, and is the one least open to objection. The names of' German, Jersey, and Champlain bloomary are too local, and these adjectives are thought unnecessary by those who use the process, and we shall not therefore describe it under any of these names, but as the American Bloomary process.

Jan 1, 1880

By L. E. Young

The purpose of this paper is to start a discussion on: (I) methods of supporting the immediate roof, particularly of local areas of poor roof, during the mechanical loading of coal; (2) methods of increasing the rapidity of the movement of the mining faces so that, without the use of cribs, jacks, park walls, and filling, there will be no danger to men, equipment, and working places from the subsidence of the overlying strata. In the Pittsburgh district the application of mechanical loading devices in mines working in the Pittsburgh seam has been retarded by the difficulties of holding and handling the draw slate. Normally the thickness of this slate averages about 8 in. but the hardness varies, and a cut of coal cannot always be loaded without placing posts or crossbars to support the slate. Locally, the slate may be thicker and special methods of support may be required. If crossbars are placed to hold the slate when the coal averages 5 ft. in thickness, the standard methods of transporting the coal cannot be followed, and the use of conveyors may be desirable. Very little information is available on the effect of increasing the rate of movement of advancing or retreating break lines or longwall faces. A few British publications have presented some data but all such data relate to longwall faces that have moved not more than 6 ft. a day. The most rapid rate of movemerit of longwall faces in Germany is 6 ft. per day. In the ordinary hand-loading mine in western Pennsylvania break lines on full retreat will move about 2 ft. per day. If loading machines are used under similar conditions the rate of retreat may reach 4 ft. per day. In a mine where coal is loaded by hand on conveyors three shifts per day, the rate of retreat has ranged from 11 to 16 ft. per day, with an average of 13 ft. If mobile loading machines could be used to load on conveyors on break lines, the rate of retreat should be increased substantially During 1935 and 1936, the United States Bureau of Mines, under a cooperative agreement with the Pittsburgh Coal Co., carried on studies of roof movement at Montour To. 10 mine. The work war done urider the direction of Mr. H. P. Greenwald, Supervising En neer, Experi-

Jan 1, 1938

By W. O. Philbrook

An engineering analysis indicates that the coke rate in present blast-furnace practice is set not by chemical or thermal needs but to give adequate charge permeability for economical driving rates. An equation showing interrelations among pressure drop, gas flow, and charge characteristics has been derived. Flooding conditions and the location of the fusion zone are discussed. Maximum ore size is probably limited by chemical re-ducibility rather than by heat transfer. THE intention of this paper is to show that the ].imitations on the production rate and coke requirement of the iron blast furnace are not primarily chemical or thermal in nature but are related to characteristics of the burden and operation that govern gas flow, heat transfer, and stock movement. A semiquantitative analysis will be developed in terms of standard engineering principles to give a useful picture of the relative importance of physical and mechanical factors in contrast with the chemical features of the process that are more commonly emphasized. Most of the details of calculation have been omitted in the interest of brevity and to avoid submerging the rnain points in a sea of arithmetic. Numerical values have been arrived at by objective methods from reported operating data or by reasonable estimates of material properties where exact data are lacking and then tested to see how well they fit practice, rather than by working backward to find what assumptions are needed to give the desired answers. The analysis is oversimplified in many ways because exact engineering relations have not yet been studied for bed distributions as complex as are known to exist in the blast-furnace stock column. One objective of this paper is to show that the blast furnace, in spite of its complexity, can be at- tacked by engineering methods in the hope that this viewpoint will stimulate the kind of research needed for a more exact treatment. The basic ideas and many of the conclusions presented are qualitatively well known. A careful literature survey to credit the source of all observations not original to the author would indeed be voluminous, and such has not been attempted. T. L. Joseph's Howe Memorial Lecture' gives an excellent background of what is known about the internal workings of a blast furnace. Other important reference works or sources of specific information will be noted. It is hoped that the present paper will contribute something new, in method of attack and interpretation, that will aid in a clearer understanding of how to operate the blast furnace to best advantage. Factors Limiting Production and Coke Rates The rate of combustion of coke in a blast furnace, as in any fuel bed, is exactly proportional to the rate at which air is supplied. It is axiomatic, then, that the production rate of a furnace is limited by the rate at which it will take wind, i.e., burn coke, and the amount of coke that must be burned at the tuyeres to make a ton of iron of suitable composition. These two possible limiting factors will be considered briefly in the order mentioned. One common restriction on wind rate is flue-dust production. Since the volume of top gas is nearly proportional to the blast volume (by a factor of about 1.35 on a dry basis), an increased wind rate causes a correspondingly increased linear velocity of top gas in the throat of the furnace. The higher

Jan 1, 1955

By E. S. Machlin, Morris Cohen

GRENINGER and Troiano' were the first to establish the fact that the habit planes of mar-tensitic products are usually planes of high indices. In steels containing 0.55 to 1.4 pct C, the habit plane indices are {225}A.* In steels with more than 1.5 pct C and in Fe-Ni alloys, the indices are {259In. The presence of both habits in certain alloy steels has been reported recently." Several investigators"-" have subsequently attempted to provide an understanding of these complex habit relations. Bowles'6 work is the most recent and the most successful. Like Greninger and Troiano, Bowles concluded that the transformation occurs in two steps, the first, a strain (or displacement) that is homogeneous throughout the volume of the martensitic plate, while the second is a strain that is homogeneous only within relatively small portions of the martensitic plate. The first strain yields the measured tilt of the specimen surface, but does not produce the final martensitic structure. This and the correct lattice orientations are achieved by the second strain. Bowles also reasoned that each strain could be described by the motion of a plane of no rotation and no distortion (hereinafter called the invariant plane) in a direction not necessarily contained in the plane.** In applying these considerations to steels with {225}a habits, Bowles found that the habit plane coincided with the invariant plane of the first strain, a result which signified that the atoms move along certain paths during the transformation. Whether this correlation results from the existence of some sort of a plate nucleus6 lying along the invariant plane of the first strain, or whether the invariant plane primarily defines the preferred directions of propagation of the first strain, will be discussed in a later section. There are two obstacles to the general acceptance of Bowles' treatment: 1—it has not been shown that elements of his double-strain analysis are unique, and 2—it is not known whether his treatment applies to transformations yielding the {2591A habit. Unless these two questions are resolved, the correlation between the habit and invariant planes in the {225}A systems might be regarded as coincidental. Experimental Procedure Using a 70 pct Fe-30 pct Ni alloy as an example of a {2591A habit system, preliminary attempts were made to obtain a double-strain solution based on a Nishiyamax** set of orientation relations and on a Greninger-Troianot set, adopting the stereographic technique described by Bowles" who used the Kurd-jumow-Sachstt set in connection with the {225}A habit. These attempts were unsuccessful because the method is essentially one of trial and error and requires either exceedingly good luck or a prior knowledge of the results being sought. Consequently it was decided to measure independently the strain associated with the formation of a martensitic plate as well as the habit-plane indices of the particular plate. By means of matrix algebra, the measured strain was applied to the austenite lattice, whose orientation with respect to the strain was determined, in order to ascertain whether the resultant structure would have the lattice of martensite. This was not found to be the case, and hence it was assumed that the measured strain was the first of two Bowles-type strains, characterized by the motion of an invariant plane. A solution of this displacement was obtained in terms of the invariant-plane indices and the direction of motion of the atoms. Then the second strain

Jan 1, 1952

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

By W. A. Tiller

The unidirectional freezing of a semiinfinite liquid from one end has been treated by calculating the solute and temperature distributions in the liquid and solid phases with time, when the solid-liquid interface advances at a rate proportional to (time)lt2. The nucleation probability for new grain formation is calculated as a function of the constitutional and thermal properties of the alloy, the pouring conditions and the catalytic efficiency of the nucleating agents. The transition from columnar crystal formation to equiaxed crystal formation is assumed to occur at a critical nucleation frequency for a particular alloy and the quantitative dependence of the ratio (columnar zone length/equiaxed zone length) upon the freezing conditions has been predicted. The effects of (i) fluid flow in the liquid, (ii) heat transfer through a mold wall, and (iii) a finite ingot length, have been explicitly tveated as departures from ideality. These departures from ideality are found to have very important consequences on the ingot stmcture. In Part I&apos; of this series, a qualitative description of the general ingot structure was developed. The factors that determine i) the ratio of the equiaxed zone length to columnar zone length and ii) the grain sizes in these zones, were discussed. In the present paper, topic (i) will be treated quantitatively, and it is intended that topic (ii) will be treated quantitatively in Part 111. The complete treatment has been split in this manner for ease of development and coherency of presentation. The treatments are quite mathematical in nature and, although some of the conclusions to Part 11 depend upon the treatment presented in Part 111, it was felt that the intended audience would find the material more readable and more useful in its present form. To this same end, it seems worthwhile to reiterate some of the qualitative aspects of grain nucleation during ingot solidification before embarking on the mathematical description. QUALITATIVE ANALYSIS In the conventional method of casting, a liquid alloy with a certain degree of superheat is poured into a mold. The outer rim of liquid metal cools rapidly to the liquidus temperature of the alloy and begins to undercool. As the degree of undercooling increases, nuclei of solid begin to form in this chill layer, this nucleation being catalyzed by certain heterogeneous particles in the liquid. The grains in the chill layer which are generally of random orientation, begin to grow inwards because of heat conduction through the mold. The grains usually develop a columnar shape since the frequency of nucleation of new grains in the liquid ahead of the advancing interface is generally insufficient to seriously impede the growth of the original grains. Due to the slow diffusion rate of solute in the liquid, a solute distribution is formed in the liquid adjacent to the interface which is either an excess or a depletion if the partition coefficient, ko, of the solute is < 1 or > 1, respectively. Thus, the liquidus temperature of the liquid adjacent to the interface is a function of position. The actual temperature in the liquid is also a function of position and the temperature gradient at the interface decreases as the interface moves away from the mold wall. Since the rate of advance of the interface decreases with time, the equilibrium temperature distributions and the actual temperature distributions as a function of interface position, X, can be illustrated as in Fig. 1. Thus, a region of liquid may exist in which the actual temperature is below the liquidus temperature. This liquid is contitutionally supercooled and therefore unstable with respect to the nucleation of new grains. Now, since the supercooling in Fig. 1 increases as the interface moves further away from the mold wall, the nucleation rate of new grains will increase. When the nuclea-

Jan 1, 1962

By Gerhard Derge

The rapidity of oxygen steelmaking has created renewed interesl in the mechanisms and kinetics of the various processes involved. These studies can now be approached with increased confidence because of the more adequate thermodynamics, physical chernislry, and relevant engineering infornzation available. These combine to offer promise of useful control and automation if the details of each specific problem can be sufficiently well-defined. The hot filament microscope provides new insig-hi into many of these problems by direct observation at temperature, allowing the appraisal of the relative importance of thermal gradients, convection, and intermediate phases. All of these have a direct bearing on the overall rates and control of most pyrometallurgical processes. It is one of the special privileges of the Howe Lecturer to become better acquainted with this distinguished man. All of us interested in the metallurgy of iron and steel have developed some sense of his widespread influence by the annual reference to his work in these Memorial Lectures. Each lecturer since 1923 has been able to identify his personal specialty with the broad interests of Professor Howe. This has become even more rewarding with the background information from Professor Gensamer&apos;s monograph, "Henry Marion Howe&apos;s Contributions to Metallurgy, which brings out his happy combination of intellectual and professional activities. Beyond this, I found my personal bond with Professor Howe in his book on The Metallurgy of Sleel first published in 1891.&apos; After a detailed discussion of the dephosphorizing action of slags, he relates the mineral species identified in the frozen sample to the chemistry of the fused slag with the question, "Is it not most philosophic to hold that these independent entities were wholly integrated in the initial magma; that their presence in it was wholly

Jan 1, 1968

By Robert A. Colten, Frederick C. Hull, Robert F. Mehl

It is known that pearlite forms from austenite by a process of nucleation and growth, and that the rate of formation of pearlite may be described by a rate of nucleation and a rate of growth.l,2 The manner in which these two quantities operate to produce the observed isothermal reaction curve has been analyzed in a paper published in I939.3 Two types of process were described: (I) that in which nucleation occurs at the grain boundaries of the parent phase, with the nodules growing toward the centers of the grains, initially as hemispheres and then after impingement as roughly radial-columnar structures; and (2) that in which nucleation occurs generally, with the nodules growing to full spheres until impingement with other growing nodules restricts growth. Both cases are met in the formation of pearlite from austenite (Fig. I);2,4 the former, occurring near the knee of the S-curve, has been named "grain-boundary transformation," and the latter, occurring at temperatures near Ael, has been named "group-nodule transformation." In developing our knowledge of the factors that determine the rate of formation of pearlite from austenite, it is important1,2 to obtain data on the rate of nucleation and the rate of growth of pearlite. Such data, when obtained near the knee of the S-curve, will furnish information of use in understanding the factors that affect hardenabil-ity; when obtained at higher temperatures, such data will be useful in understanding the behavior of steels that during heat-treatment react to pearlite.2 It is the purpose of this paper to present data on the rate of nucleation and the rate of growth of pearlite in dependence upon composition, grain size, temperature, and the degree of homogeneity of the parent austenite. The studies are restricted chiefly to plain carbon commercial steels." Previous Data on Rate of nucleation and rate of Growth Data on the rate of nucleation and the rate of growth of pearlite have been published by Scheil and Lange-Weise,5 by Mirkin and Blanter,6,7 by Meh1,l and by Dorn, De Garmo and Flanigan.2, It is difficult to interpret the data, for in most cases too little information is given on austenitizing temperatures and times, the state of homogeneity of the austenite (presence or absence of carbide, etc.), austenite grain size, and mode of formation of pearlite at the temperatures given. Except for the approximations of Mehl and the work of Dorn, austenite grain size was disregarded, though it is well known

Jan 1, 1942

By Walter Crafts, D. C. Hilty

The liquidus diagram for the iron field of the Fe-S-O system has been derived experimentally. The solubility of oxygen in molten Fe-S alloys has been measured at several temperatures and found first to decrease slightly and then increase rapidly with increasing sulphur content. IT is well-known that the types, distribution, and amount of inclusions in any given steel are closely allied with the oxygen and sulphur contents of the metal, so that the term "deoxidation" as conventionally applied in steelmaking refers not only to the control of oxygen and oxide inclusions but to collateral modification of sulphide inclusions as well. Inclusions commonly occur in steel as mixtures of oxides and sulphides, sometimes closely associated and sometimes apparently completely divorced. Their effects on the properties of the metal may vary widely depending on their types and distribution as well as on their quantity. The mechanism by which inclusions form, however, and the means for controlling it are exceedingly complex and not well understood. Nevertheless, as described by Benedicts and Lofquist&apos; and by Wentrup&apos; all oxide and sulphide inclusions, excluding mechanically entrained matter, must result from specific modifications of the basic equilibria of the Fe-S-O system. In an investigation of the mechanism of deoxidation and inclusion formation being carried out at the Union Carbide and Carbon Research Laboratories, it became evident that quantitative data for the fundamental Fe-S-O system were essential to a better understanding of the problem. Consequently, the liquidus surface of the portion of the Fe-S-O diagram of interest in steelmaking has been determined, and the solubility of oxygen in liquid iron containing sulphur has been measured. Fe-S-O Diagram The portion of the Fe-S-O diagram of specific interest in steelmaking is the Fe-FeS-FeO corner. Of the contiguous binary diagrams for this partial system, only those for Fe-FeO and Fe-FeS are known with reasonable certainty.3 Several attempts to derive the FeO-FeS diagram have been made, chief among them being the work of Giani as reported by Oberhoffer,4 and, more recently, that of Vogel and Fulling." Although both Giani and Vogel and Fulling published diagrams for the FeO-FeS system, their observations indicated that the oxide component approximated Fe3O4 rather than FeO, so that there is doubt whether the system is truly binary. Benedicts and Lofquist and also Wentrup published qualitative sketches of the ternary diagram based on the assumption that it was of the type described by Marsh for a ternary system in which two of the contiguous binary systems are simple eutectic systems and the third exhibits a solubility gap in the liquid. Apparently, however, the only previous effort to establish the diagram experimentally was that of Vogel and Fülling whose results are reproduced in Fig. 1. Although defining approximately the limits of the miscibility gap and the location of the ternary eutectic, point E in Fig. I, Vogel and Fülling&apos;s diagram must be considered only semiquantitative. It was derived from a limited number of observations mainly along two quasi-binary sections, and the directions of the tie-lines and the location of the critical point, K in Fig. 1, were estimated by computation. Experimental Procedure The experimental technique employed for the present investigation involved melting mixtures of ferrous sulphide and ferric oxide in contact with iron. Since it was considered that in this part of the system the vapor pressures of sulphur and SO, are so low that they would not affect the results significantly, the melting was carried out in a current of argon to sweep out products of any initial re-

Jan 1, 1953

By Leon W. Dupuy

INTRODUCTION A BRIEF elemental discussion of the fundamental factors involved in diamond drilling often fills a need, particularly when a mine operator is contemplating for the first time an exploratory drilling campaign. Mr. James A. Barr, of the Mining Methods Committee of the Institute, has suggested that many engineers must undertake a drilling program of one kind or another and, in the case of diamond drilling, sometimes even are at a loss as to how to start correspondence. The Bureau of Mines has acquired much experience in managing exploratory diamond-drilling activities. Its activities in diamond drilling included exploring for potash in Texas, Utah and New Mexico 1-4 during the 1920&apos;s. The Strategic Minerals Exploration program was started in 1939 and was materially expanded during the war to include critical and essential minerals. At the peak of its war-time activity more than 200 engineers were employed, a majority of whom supervised diamond drilling. Many of them had little experience with such work prior to their employment with the Bureau, and it was necessary to instruct them in their duties. The purpose of this paper, therefore, is to present the fundamentals of exploratory diamond drilling from the viewpoint of management in such a way that they will serve as a basis on which those beginning exploratory diamond drilling may build an experience and acquire ability to direct exploration as they gain that experience. SELECTION OF METHOD OF DRILLING Selection of the method of drilling is governed by the type of material to be penetrated and by the type of sample needed to determine the quality and importance of a deposit. Types of drills that might be used for a given job include diamond drills, churn drills, hand auger drills, power auger drills, bucket drills, and rotary drills (sometimes called "seismograph rigs"). Each type has a specific field in which it is most useful. While the Bureau of Mines utilized all the types of drilling mentioned, diamond drilling was used on a majority of its exploratory projects. FACTORS GOVERNING SELECTION OF DIAMOND DRILLING The prime consideration in selecting a method of drilling is first to determine what results are desired and then to choose a method that will furnish reliable data in the ground to be penetrated. Use of diamond drills permits recovery of a core as well as sludge at a comparatively low cost. The core provides an excellent means of studying the formation being drilled and furnishes much information that would be difficult to obtain otherwise. Diamond drills will recover a satis-

Jan 1, 1947

By David R. Mitchell, E. C. Carris

THE particular field of application of machines utilizing air currents as the primary separating medium is in the cleaning of fine sizes of bituminous coal. Approximately 18,000,000 tons of bituminous coal was cleaned by air machines in 1947, but such machines have not yet been applied in the cleaning of anthracite. This chapter is limited to a description of the processes in which the separation between coal and refuse depends mainly on a difference in specific gravity. Dry processes depending on differences in coefficient of friction, shape, or other property, are described in chapter 17. The possibility of using air for the separation of coal from refuse was recognized early by mining men and many attempts were made to develop commercial machines. Some of these early machines are described by Berrisford,1 Chapman and Mott,2 and Mitchell.3 Only two machines are extensively used today in the United States, the Stump air-flow jig and the American oscillating table. GENERAL CHARACTERISTICS OF AIR CLEANING MACHINES The principles of gravity concentration and the properties of air as a medium for separation were explained in chapter 9. It was pointed out that because of the low density of air a medium of sufficient density has to be built with the material itself. Hence there must be some device to impart to the bed the necessary mobility for proper classification. It was also noted that the compressibility of the air may cause "geysering" of the bed and disturbance of the hindered-settling classification if the correct balance of conditions is not maintained. Most devices use a vertical upward current of air through the bed of material. They differ by the method of imparting mobility to the bed and the method of removing the refuse. In general terms, the air machines can be divided into three types: 1. Pneumatic jigs where the air current is pulsated. 2. Pneumatic tables where the refuse is diverted from the direction of flow of the clean coal by a system of riffles fixed to the deck.

Jan 1, 1950

By M. R. Pickus, I. W. Pickus

Ordinarily age-hardening is thought of as being associated with a limited solubility of one metal in another. Much less has been written about the type of age-hardening that attends the formation of superstructures. Solid solutions generally have a disordered or random arrangement of atoms; that is to say, in a unit cell, such as that of the face-centered cubic lattice, there is no distinction between atomic sites. Atoms of a given metal may occupy cube corners or face centers. Under certain conditions, however, some alloys develop what is known as an ordered structure. In this case, cube corners would be occupied by only one type of atom and face centers by another type. Associated with this ordering process are many interesting changes in physical and electrical properties. Moreover, in many instances the alloys become susceptible to age-hardening. From the evidence now to be described, it appears that age-hardening in 14-carat gold alloys is due to the formation of both a superstructure and a precipitate. Alloys of the metals gold, silver and copper were known in antiquity. The available knowledge regarding their constitution has been ably summarized and extended by Sterner-Rainer,&apos; Jänecke,2 Carter,3 Wise,4 and Coleman.5 Despite the long familiarity with these alloys and the numerous investigations of their properties that have been made, there is still much that remains unexplained. It has been known for a long time that the hardness of these alloys is closely related to the rate of cooling. Similar changes have been observed in the binary gold-copper systemI6 one alloy of which corresponding to the formula CU³AU, has been the subject of a careful and competent report by the English investigators, Sykes and Evans.7 They have established the fact that the shift of atoms from the ordered to the disordered condition takes place in some critical temperature range. At temperatures above the critical range the structure is random, and at temperatures below it the structure is ordered. No difference between these two structures is revealed by the microscope. Both have a face-centered cubic lattice and complete solubility, so that there is no evidence to suggest that the changes in properties are associated with a phase change. The more slowly the alloy is cooled, the higher is the degree to which the ordering process proceeds and the more marked is the increase in hardness. As experimental data were accumulated on I4-carat gold alloys, several contradictions arose. Certain observations tended to confirm the existence of a superstructure, while other observations seemed to be inconsistent with such a transformation. Present Investigation As a focal point about which to develop this subject, it is expedient to consider first

Jan 1, 1943

By L. R. Page, J. J. Norton

EFFECTIVE methods for determining grade and reserves of pegmatites in advance of mining have been developed in recent years. When intensive work began on the economic geology of pegmatites during the early years of World War 11, it was widely believed that grade and reserves could be estimated only in a most general way. The literature indicated that not all pegmatite deposits are unpredictable, but statements emphasizing unpredictability and irregularity seem to have been more widely accepted. Many standard references reflect the prevailing opinion that minerals: are unsystematic in their occurrence in pegmatites. Pegmatites have been described as "notorious for their irregular structure," and minerals within pegmatites as "irregularly distributed." "irregularly disseminated," of "erratic occurrence," "proverbially erratic in distribution," "characterized by extreme irregularity in ... size and distribution of the essential minerals, and variety and proportion of the accessory minerals," and "spotty.&apos;"" Over many years, however, geologic techniques have been applied with increasing success to economic analysis of pegmatites. Investigations, chiefly since 1939, have shown that mineral distribution and structure of pegmatites are largely systematic and that detailed geologic study can be used to predict the size and shape of mineral deposits in pegmatites. Because the writers are most familiar with the pegmatites of the Black Hills, S. D., examples cited are from that area." Pegmatites mined in other dis- * All examples are described more cornpletely elsewhere.: tricts are similar to those in the Black Hills," and the techniques described here have been applied by geologists and engineers working in other districts. In actual practice few pegmatite mine operators attempt to make accurate estimates of grade and reserves in advance of mining. Many deposits are too small for mining except on a very small scale; few pegmatite mines have more than ten employes. Hence there is little systematic preparation for mining, and the capital outlay may be so small that only a general knowledge of reserves is necessary. Technical personnel are rarely employed by pegmatite mine operators to make such estimates. In the future, however, as capital outlay becomes larger, estimates of grade and reserves will have to be more accurate. Geologic Aspects of Determining Grade and Reserves Estimating grade and reserves requires that the type of pegmatite, the size and shape, and the internal structure be determined by detailed geologic mapping and careful mineralogic study. The wide variations in the texture and distribution of minerals within many pegmatite deposits make a thorough geologic study of this kind necessary before it is possible to decide what sampling methods should be used to determine mineral content or grade. Types of Pegmatites: The first step in economic appraisal of a pegmatite is to determine the min-eralogical and structural type. In general, pegmatites may be classified into two groups: 1) those in which component minerals are more or less evenly distributed throughout the entire body and show relatively minor variations in texture, and 2) those in which component minerals have been segregated into units with recognizable differences in texture, mineralogy. or both. Johnston" has classified these types of pegmatites as homogeneous and heterogeneous, respectively. Cameron et al.10 have used the terms ~inzoned and zoned for similar types. The difference between the homogeneous and heterogeneous types is of great commercial importance. Homogeneous pegmatites can seldom be mined where the products are concentrated by the hand methods now commonly used, but they have been mined in a few places where a milling process has

Jan 1, 1957

By Simon H. Ash

The coal-mining districts of Washington are mainly west of the Cascade Mountains; Fig. 1. The mines are on the foot hills of the slope, the lignite fields of Lewis and Thurston counties extending into the valleys west of the mountains. An exception is the Roslyn field, a small but important area on the eastern slope. If western Washington is divided into three areas from north to south, the bituminous coal fields and most of the active operations will be found largely in the middle area. The southern portion contains lignites over a large area. In the northern portion, mining is practically restricted to one mine, the Bellingham, which is working a subbituminous coal seam near the city of Bellingham. The degree of alteration that the coal of a particular field has undergone may be gaged roughly by the position of the field with reference to the Cascade Mountains. The lignites of Tenino, Tono, Mendota, and Castle Rock, on the railway line connecting Seattle and Portland, occur in a region of low relief, in which the Eocene coal measures have suffered only minor disturbances. Subbituminous coals occur in the foot hills, as at Renton, Newcastle, and Bellingham. Coalg high in fixed carbon are found nearer the mountains, where the measures have been sharply tilted and folded, as at Black Diamond and Carbonado. The two typical anthracite fields are located still higher, in the rugged mountains where outcrops appear both in deep gorges and on ridges at elevations approaching 5000 ft. At Carbonado is found the only semianthracitc seam worked on a commercial basis. The occurrence of this seam in a region of bituminous coal is due to the nearness of an igneous sill, which has changed its character from bituminous to semianthracite. Purpose of Paper On account of the various faults and dips and the varying nature of the wall rock, many difficulties are encountered in mining and winning the coal. The paper gives some of the methods used in mining and, in some detail, the conditions that affect the efficiency of these methods.

Jan 1, 1925

By D. W. Fuerstenau, P. C. Kapur

The kinetics of green pelletization in a laboratory balling drum have been studied, using pulverized limestone as a model system. The growth characteristics of green pellets were found to be extremely sensitive to the moisture content of the material. Empirical kinetic equations, which incorporate a function of specific surface of the pellets as the criterion for growth potential, have been found to describe growth in a nucleation region and in a ball growth region. The rate constants in the kinetic equations are strongly dependent on the moisture content of the material being pelletized. Size distributions of the balls at different stages of pelletiz-ing are also discussed. In many industrial chemical processes, particulate matter can only be utilized if it is in an agglomerated form, such as pellets. Pelletizing is now widely used in iron ore technology1, and it has also been applied to a number of diverse fields such as the production of cement-kiln feed2, fertilizers3, and fluorspar4. Recently, it has been proposed to pelletize dispersion-type ceramic nuclear fuel elements5. In iron ore technology, for example, the production of agglomerates by pelletizing involves two major steps: 1) the preparation of green balls by rolling particles in a suitable balling device and 2) the firing of the green balls to form compact, strong bodies upon sintering. The critical step in a successful iron ore pelletizing operation is generally considered to be the balling operation1. In this paper, which is not concerned with the sintering of green pellets, the words green pelletizing and balling will be used interchangeably. Green pelletizing, or balling, will be defined as the process of forming larger bodies by rolling fine particles on a surface without the application of direct pressure. Two recent literature surveys6" indicate that in spite of the considerable amount of industrial pelletizing, very little is known about the fundamental principles of balling and its kinetics. The first reported research on the kinetics of pelletizing is the work of Newitt and Conway-Jones8. Using silica sands of different sizes in a batch laboratory balling drum, they found that the average green pellet diameter increased linearly with time at constant drum speed, and qualitatively the growth rate increased with moisture content. Generalized conclusions cannot be drawn from their research since the materials which they pelletized were sand and sand-silt mixtures rather than comminuted materials. Moreover, Newitt and Conway-Jones used testing sieves to estimate the size distribution of the green pellets, and this technique limited the range over which they could study the growth kinetics of the pellets. Bhrany and co-workers9 investigated the kinetics of balling iron ore fines on disk pelletizers ranging in diam from 1 to 18 ft. In their investigation, balling was carried out as a continuous operation, and growth kinetics were studied in terms of retention time of the material on the disk. Although the feed material in their study was quite coarse (the maximum size being about 1/2 in.), they also found qualitative relationships between pellet growth and water content, and feed size. In the present investigation, a number of innovations were introduced that refined the experimental measurements and established the reproducibility of balling experimentation. This enabled extension of the range of measurements to include study of agglomerate nucleation phenomena in the fractional mm size. This paper presents a detailed analysis of the nucleation and growth of green pellets in a laboratory balling drum. MATERIALS AND METHOD Pulverized limestone of specific gravity 2.72 was used as a model system in these studies. It has already been established that the balling characteristics of limestone and silica are similar to those of iron ore concentrates 2,8,10, depending on physical, rather than chemical, properties of the particles. The size distribution of the limestone was determined by a wet-dry sieving technique in the sieve range and by a sedimentation balance in the sub-sieve range. Fig. 1 presents the size distribution of the limestone used in this research. This figure shows that the material is finer than 200p (65 mesh) and that 25% of it is finer than 12. The specific surface area of this powder, as measured by BET gas adsorption methods,

Jan 1, 1964

By George M. Enos, Robert J. Anderson

This paper gives a summary of tests made on the accelerated electrolytic corrosion of the tin brass, 70:29:1 copper-zinc-tin (admiralty metal), of different grain sixes in various electrolytes. There has been great difference of opinion as to the effect of grain size on the corrosion rate of brass, particularly in condenser-tube practice, but so far as is known no information has been published on the subject. It has been assumed, on the basis of the amorphous-cement theory, that fine-grained brass would corrode more rapidly than coarse-grained because the amorphous phase is more soluble than the crystalline and there is more cement per unit area exposed in the fine-grained material. In previous work on the corrosion of metals and alloys in acid mine waters from coal mines,1,2 it was found that the grain size, within a restricted range, had practically no effect on the corrosion of the brass 70:29:1 copper-zinc-tin: In the tests made, samples of three grain sizes were included; viz., 0.025, 0.035, and 0.075 mm. diameter (1600, 817, and 177 gr. per sq. mm., respectively), and the average losses on exposure to the most acid of three waters were 7.07, 6.80, and 6.72 mg. per sq. cm. per day (24 hr.), respectively. No distinguishing features were observed on microscopic examination of the corroded samples. In two other mine waters, the corrosion losses were substantially the same for the respective samples. These tests were -incidental to other tests and were not sufficiently comprehensive to warrant drawing definite conclusions. In further work with the accelerated electrolytic corrosion test, as developed recently in the Bureau of Mines, tests were made

Jan 1, 1924

By David E. Nicholas

INTRODUCTION In this paper, a numerical process for selecting a mining method, with the emphasis on underground mass mining techniques, such as caving, induced caving, and stoping, is proposed. In the past, selection of a mining method for a new property was based primarily on operating experience at similar type deposits and on methods already in use in the district of the deposit. Then, the chosen method was modified during the early years of mining as ground conditions and ore character were bet- ter understood. Today, however, the large capital investment required to open a new mine or change an existing mining system make it imperative that the mining methods examined during the feasibility studies and the method actually selected have a high probability of attaining the projected production rates. Although experience and engineering judgment still provide major input into the selection of a mining method, subtle differences in the characteristics of each deposit, which may affect the method chosen or the mine design, can usually be perceived only through analysis of measured characteristics. The parameters that must be examined when choosing a mining method include: 1) geometry and grade distribution of the deposit; 2) rock mass strength for the ore zone, the hanging wall, and the footwall; 3) mining costs and capitalization requirements; 4) mining rate; 5) type and availability of labor; 6) environmental concerns; and 7) other site-specific considerations. This paper encompasses a detailed look at the first two parameters since they, plus mining costs, have the greatest impact on the selection of a mining method. The proposed method selection process is for a project where drilling has defined sufficient geologic reserves, but little or no underground development has been done. Since each deposit has its own characteristic geanetry/grade distribution, and rock mechanics properties, mining method selection should be at least a two-stage process. In Stage 1, the deposit is described in terms of geometry, grade distribution, and rock mechanics properties. Using these parameters, the mining methods can be ranked to determine which are most applicable; they can then be considered in general terms of mining and capitalization cost, mining rate, type and availability of personnel, environmental concerns, and other site-specific considerations. In Stage 2, the most likely mining methods are costed out, based on a general mine plan. Mining and capitalization costs are used to determine a cut-off grade fran which a minable reserve can be calculated; economic comparisons can then be made to determine the optimum mining method and economic feasibility. During the mine planning phase of Stage 2, rock mechanics information would be used to provide realistic estimates of underground opening size, amount of support, orientation of openings, and caving characteristics, and open pit slope angles. If ground control or operational problems should be encountered with the methods being considered, modifications could be made. Although planning on paper extends start-up time, it is cheaper to err on paper than to find the error after mining has begun. METHOD SELECTION - STAGE 1 The main purpose of Stage 1 is to select those mining methods which should be considered in greater detail. The simplest way to do this is by defining those characteristics required for each mining method and then determining whether the characteristics of the deposit are suitable. However, no one mining method is so restrictive that it can be used for only one set of characteristics, as indicated by the classification system proposed by Boshkov and Wright (1973). In the mining method selection proposed, geometry, grade distribution, and rock mechanics characteristics are ranked according to their acceptability for ten general mining methods.

Jan 1, 1981