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By James J. Bryja

The production capabilities of today?s longwall systems have resulted in significant increases in retreat rates. This has in turn resulted in a heightened demand on panel development rates to assure that subsequent panels are completed in time to avoid a longwall production outage. As a means of reducing the pressure on the panel development activity a trend has developed towards the use of wider face lengths. The aim of using a wider face is to reduce the longwall retreat rate without sacrificing productivity and thereby reduce the pressure on increasing panel development rates. However, as the face width increases so too does the number of hydraulically powered roof supports that are required to control the longwall face roof. This increase in the number of units inherently translates into increases in the level of required maintenance relative to the multitude of mechanical and hydraulic components, and an increase in the time required for tear-down and installation time during the moves between panels. An obvious method of mitigating the maintenance and move-time impacts of wider faces is to employ the use of individual roof supports having a wider center-to-center spacing. This practice would serve to minimize the number of roof supports and maximize the time availability for longwall face production. With this target in mind a joint research project with DBT was initiated in 1998 to study the feasibility of using 2 m wide shields to replace the then standard 1.75 m wide shields. After four years of comprehensive work, the technical team from DBT and RAG American Coal completed the design and development of a prototype shield that would later become part of the world?s widest longwall face employing the use of shields having a spacing of +2 meters. The final spacing of the shields actually became 2.058m in order to match the standard pitch of the rack bar shearer haulage elements on the conveyor. In July 2002, the 2 m wide shields were successfully installed in LW-46 panel at RAG Cumberland mine in the U. S. The authors in this paper summarize the design considerations of and operational experiences with the world?s widest longwall face using +2 meter wide roof supports.

Jan 1, 2008

By Jorge Munoz Reyes

There are three main oil areas in Bolivia (Fig. 1) although so far only one has yielded petroleum in commercial quantities. The Sub-Andean zone is along the easternmost ranges of the Andes, bordering the large eastern and northeastern lowlands. It extends from the Peruvian frontier, north of Lake Titicaca in a southeasterly direction towards the city of Santa Cruz and from there southward to the Argentine border. This zone forms a belt about 1200 km. long by 100 km. wide, and comprises a series of parallel, very rugged, low ranges. Oil has been known and utilized by the natives in these regions since colonial times, from the large number of seepages, which in modern times have led to the discovery of many fields. The second oil zone of Bolivia lies along the eastern and southern borders of Lake Titicaca, on the Andean high plateau, at an average altitude of 13,000 ft. above sea level. It comprises an area of approximately one million hectares (2,470,000 acres). Several seepages are known here, but little development has taken place, because of the difficulties encountered, as the greater part of the territory is covered by volcanic tuffs and ashes, which conceal the structure underneath. The third area is called the "Central zone," and is in the heart of the country, in the Department of Cochabamba, covering approximately five million hectares (12,350,000 acres). This area consists mainly of broad valleys flanked by low rolling ranges. Natural seepages are not known to exist, but there are secondary evidences of the presence of oil. The outcropping rocks are mainly Paleozoic (Silurian and Devonian sandstones and shales). Albertite and other forms of polymerized petroleum have been found in this region. Of these three main oil areas, only the first one is at present productive on a small commercial scale. This zone, developed almost exclusively by the Standard Oil Co. of Bolivia, a subsidiary of the Standard Oil Co. of New Jersey, is divided from south to north into the following local fields: 1. Bermejo (On the Argentine border) 3. Sanandita 5. Camatindi 2. San Telmo 4. Caigua 6. Machareti

Jan 1, 1935

CHARLES F. WILLIS,* Bisbee, Ariz.-(written discussion?).-The consensus of the discussion of the paper of Dr. Lanza indicates that the physical examination, while it is probably a good thing, is fought by the workingman, and that, because of this fact, it has been proved unsuccessful. The physical examination standing alone is worth but little, and could easily be made a subject both of ridicule and dissension unless the company having such examination shows its own good faith in promoting a thoroughly better health program. It is easily seen why a workman would resent his employer expecting him to be physically fit, if at the same time the employer provides un-healthful, unsanitary, working conditions, or if the town in which the employees are expected to live is dirty and unkempt. One mocks the other. The employer cannot say, "You must remain healthy so that I can get by with unhealthy conditions." But if working- conditions are as good as can be obtained to keep men well, the employer can ask his men to be in a healthy condition. A State examination and standard would have many difficulties, owing to the fact that a man would pass or would not pass the standard set, thus eliminating the discretion on the part of the employer in placing men whose physical condition might well permit working in one place and not another. Any physical examination that is run for the purpose of eliminating the physically unfit is unjust, both to the worker and to the nation as a whole; a State examination would make a distinct dividing line, whereas examination by the employer is conducted with a vision of the positions available. The workman's opposition to the physical examination comes from the fact that he has been taught to believe that it is an interference in his personal affairs, that he can be clean or dirty as he chooses, that he can he healthy or unhealthy, and that it is nobody's business but his own. The war has taught us, however, that the individual is no longer the unit and that all such propositions must be based on the greatest good for the greatest number.

Jan 6, 1919

W. C. MATTESON (communication to the Secretary*).-The criticism and question raised by Arthur Knapp regarding the standardization of nomenclature is most important. Faulty rock classification-is generally the result of carelessness or ignorance on the part of the driller. Two remedies might be suggested. In a field where several large companies are operating on an extensive scale, a geologist from each concern might be assigned to superintend the gathering of well-log data and the classification of samples. The geologists from the several operating companies might then combine their data, which would doubtless give valuable information to all interested parties. At present, coordination is not a big factor, unfortunately, but the time will come when conservation will demand such systematic coordination on the part of competing companies. The second remedy lies in instructing and educating the driller to a thorough understanding of the importance of an accurate log and correct classification of the various formations. The writer does not agree with the statement that "90 per cent. of the logs as taken today are absolutely worthless to any one but the one who has taken the log." While mistakes in nomenclature often occur, the driller is generally able to classify the important water-, oil-, and gas-bearing formations with a fair degree of accuracy. Such information is often sufficient to permit accurate correlation and also constitutes valuable data for projection purposes. It must be borne in mind that to attempt to use well-log data in a strict scientific sense of accuracy is impracticable and impossible. A broad interpretation and a comprehensive knowledge of the practical limits of such' information are essential in applying it successfully. Even experienced geologists do not always agree on rock classification. The question as to what constitutes correct nomenclature should receive the earnest and immediate attention of geologists, operators, and producers. Although standard textbooks on geology give correct definitions and descriptions of the general rock species, such textbooks fail to develop the subject in sufficient detail for the work under consideration. A committee composed of appointed members from the American Institute of Mining Engineers, the Geological Society of America, and the

Jan 6, 1917

By M. H. Richman, W. D. Sproul

THE indexing of a field-ion micrograph is in many cases similar to the indexing of the poles of a stereo-graphic projection.* If one has a standard projection as a guide, the task of indexing is relatively simple. In this way, field-ion micrographs of bcc and fcc wires have been oriented from projections available in most any text on X-ray diffraction. These books always illustrate the projections for the bcc and fcc structures and even for a particular hcp structure. There is no "standard" hcp projection because the angles between planes depend on the c/o ratio of the unit cell. In order to index field-ion micrographs of hcp metals, one must compute the angles between various planes—a rather laborious task. In recent work,, we have had to identify the structure and index the orientation of field-ion micrographs of the compounds WC and W,C. To overcome the problem of computing angles by hand or calculator, a program was written in Fortran lV for use on the IBM 360, Model 50 which will compute all angles between planeswith indices (hlklll) and (17,k,l2) in the range from (447) to (444) for any given c/o ratio. The program, which is more specific than that of Camp and clum, was so written as to take advantage of the multiplicity of the hexagonal system, and, for the limits defined above, only 26,649 values out of a possible 265,721 values had to be computed. This is a 90 pct saving in time (and cost) and was accomplished in the following way. Because the lattice parameters of the hexagonal crystal system are defined such that: a = b * c [1] the I index does not enter into the multiplicity (i.e., it cannot be transposed with the h or k indices), and all possible values of h and I, from 4 to 4 must be used—a total of eighty-one combinations. The index h2 varies the most—it must assume values from - Ill,: to 3Ihl. The indices kl and k2 are always equal and vary

Jan 1, 1969

By F. D. Mahone

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than Pper cent. with commercial success. Standard Cottrell Apparatus The present standard Cottrell apparatus consists essentially of the electric treater and a settling or trap tank. The treater is a galvanized-iron tank approximately 3 ft. in diameter and 10 ft. high, which con-

Jan 1, 1924

By A. J. Lanza

THE prevention of illness among the employees of the mining industry is especially important in view of the importance of the industry, the unsettled conditions of labor, which emphasize the economic necessity for conservation of labor, and for humanitarian reasons. The burden of chronic illness is altogether unwarranted and unnecessary. If the industry is to maintain its labor supply in an efficient manner and keep the standard high, it is essential that it make every effort to keep its labor in good physical condition. The basic principles underlying health conservation are the same for any industry, but they are here applied especially to the mining industry, and more particularly, perhaps, to metal mining, as it is with this phase of the industry that the writer is most familiar, and as it is conceded that metal mining presents more health hazards than coal mining. The first step in the prevention of illness lies in securing employees who are in sound health and free from organic disease. I do not mean that all men who go underground should be physically perfect, but they should be free from organic defects of the heart, lungs, and other organs, or from anatomical defects that would- markedly increase their liability to accident. The number of men working underground in mines in this country whose physical, condition totally unfits them for such work presents-a situation that should not be allowed to continue, and which I believe is 'not equalled in any other, industry in the country. There is but one way to secure men who come up to the required standard, . and that is by a thorough physical examination before employment. I am fully aware of the objections felt toward such a procedure by many employers and employees. There is much to he said on both sides, but to any one who is at all familiar with the mining industry as it is today in this country, and who approaches the matter with an unbiased mind, there can be absolutely no doubt as to the necessity for physical examination. As a purely logical proposition this is self-evident, but there remains the further necessity of placing physical examinations on such a

Jan 2, 1919

By J Centofanti, D Conti, R Riske, C Morley, A Cook

Why is it so difficult? Why are there differences throughout the resources industry in how reconciliation factors are reported and calculated? Why is there no standard formula to use? These are common questions asked when mining companies try to compare reconciliation results across operations or attempt to undertake internal or corporate governance reporting processes. For many mining companies the calculation of reconciliation factors is often a very time and resource intensive part of mandatory reconciliation reporting. Some major mining companies, that move millions of tonnes of material per annum, dedicate full time resources to the calculation of reconciliation factors. The willingness of these companies to set aside resources demonstrates the value that operations place on good reconciliation reporting. Reconciliation is about measuring the variance between two like measures at different points along the mining sequence. It can be undertaken between predictive models, forecast plans and actual measured performance. Calculations are used to derive a variance between two sections within the mining sequence, with the result being commonly known in the resources industry as a æfactorÆ. Mining companies use the calculation of reconciliation factors as key performance indices (KPIs) to provide a æhealth checkÆ of their operation, with variances often pointing to issues either with the accuracy of the original estimate or the quality of the measurement being used in the comparison. There are many reconciliation factors that can be calculated and reported. This paper will set out, clarify and provide a recommended standard means of calculating each specific factor that, where adopted by a company, will ensure compliance with the international reporting codes, such as JORC. Using case studies from Rio Tinto Group (Rio Tinto) and BHP Billiton Mitsubishi Alliance (æBMAÆ), and the authors experience across a wide range of mine sites, the outline of a generic solution for tracking a parcel of material from the pit through to the port along with appropriate reconciliation factors is provided. The intention of proposing standardised reconciliation factor terminology and methodology is to provide the foundations of a system to enable communication and comparison across different commodities, companies and mines sites.

Jan 1, 2009

By R. B. Adair, J. S. Browning

The Bureau of Mines conducted laboratory research to determine the applicability of heavy liquid separation to the evaluation of certain mica ores and plant products. After careful standardization of the particular mica ores and associated gangue, accurate analysis of muscovite content could be obtained from results of heavy liquid separation. Where applicable, the method should be particularly suited to the analysis of ores and control of plant operations wherein savings in time would be of considerable advantage. Specifically, there are many instances where a quick plant control method should enable the production of a more uniform grade of mica concentrate. The laboratory use of various heavy liquids for separating minerals of different specific gravities has been recognized for many years.1-8 Sink-float procedures have proven their utility as a rapid and moderately accurate means for determining the mineral content of ores, test products, and plant products in certain nonmetallic concentrating operations. A standard method of analysis for mica in ore samples has not been published or generally accepted by the mica industry. Recently, the U.S. Bureau of Mines investigated methods for analyzing mica by heavy liquid separation. This report has been prepared to make the methods available to others who may need simple, relatively rapid methods of determining the mica content of ores and plant products. The heavy liquid method of mica determination has recently been adopted by one of the major mica producers for evaluating exploration and mill control samples. DESCRIPTION OF THE ORES AND HEAVY LlQLllD The weathered mica pegmatite ores used in the investigation were obtained from commercial mica op erations in Alabama, Georgia, and North Carolina. The major mineral constituents of the ores were muscovite, quartz, kaolin, and minerals of the feldspar group. The ores also contained minor quantities of biotite, limonite, and tourmaline. A comparison of the specific gravities of the major constituents of the ores (muscovite 2.76 +, quartz 2.65, kaolin 2.61, and feldspar 2.57), indicates that an effective separation of muscovite from the other minerals can be made in heavy liquids at a specific

Jan 1, 1968

By Donald Gilbert

PRIOR to July, 1919, the sampler at each mine of the Anaconda Copper Mining Co. in Butte did his work in his own way and was responsible to the mine foreman only. At that time, the sampling at all the company's Butte mines was placed in charge of a member of the geological department and stand-ardized methods of doing the work, were adopted. These standards were incorporated in a set of instruc-tions accompanied by blueprints representing typical conditions. The main features of the instructions were as follows: All samples to be cut at breast height and horizontally, regardless of dip of vein, and the horizontal width reported. A single sample to include not more than a 5-ft. width of the breast and to weigh not less than 4 lb. for this width. Where the vein is made up of two or more streaks of different hardness or mineral content, each streak is to be sampled sepa-rately and the average value of the combined width figured. If two streaks of ore are separated by a streak of waste, which is not sampled, in obtaining the average value of the breast the waste must be figured in with a zero assay. Drifts to be sampled in the breast after each round. Raises to be sampled for each floor raised. Each end to be sampled separately and the average width and value of the two ends to be used as the average of the floor. All veins cross-cut to be sampled along the side of the cross-cut, at breast height and horizontally. Where the vein strikes at an acute angle to the line of the cross-cut, the width of sample must be corrected to show the horizontal width at right angles to the line of strike of the vein. Rill stopes must be sampled across the full mining width. In square-set stopes, each set must be sampled separately along the line of the caps. Waste portions of the vein which are mined for filling must not be included in the sample.

Jan 2, 1922

THE great event in American affairs was the sudden death of President Harding, on Aug. 2, in San Francisco. A few hours later Vice-Presi¬ dent Coolidge took the oath of office while in his father's farmhouse in Vermont and forthwith proceeded to Washington as the 30th president of the United States. The French and Belgian governments' replied to the British refusing the proposed discussion of the German offer and declaring that they would pursue their policy in the Ruhr until the German government abandoned its resistance and surrendered unconditionally. The economic collapse of Germany .appears to be nigh. Chancellor Cuno and his cabinet resigned the govern-ment of Germany on August 12, and Gustav Strese-mann, head of the People's party, accepted the task of forming a four-party coalition government. Coinci-dentally, there were food riots throughout Germany, and many persons were killed and wounded. The , National Assembly of the Turks at Angora ratified the Lausanne treaty, in the latter part of August, whereupon the retirement of the military forces of the Allies from Constantinople and the Straits began. Thus, Turkey was fully reinstated as a European power. The Greek government also ratified the Lausanne treaty and commenced to put its army on a peace basis. The number of unemployed persons in Great Britain is again increasing, which is causing much concern. The flood of crude oil and gasoline, which is severely taxing storage capacity, had its natural economic effect. Some small refiners were constrained to liqui-date in distress. The Governor of North Dakota, having acquired a supply of such cheap gasoline, insti-tuted a drastic cut in price, deliberately egging on the big refiners to do likewise. The Standard Oil Co. of Indiana accepted the challenge with enthusiasm, say-ing that it had always been its policy to sell as cheaply as any competitor. There was a humor in this situation which paved the way for the Standard to extinguish its small competitors and do by invitation of the State exactly what the muck-rakers had always charged as its greatest crime. The gasoline war spread to other states and reductions in price were made even on the seaboards. All of this was purely economic.

Jan 8, 1923

By R. V. Wheeler

A matter of much concern at present to the coal-mining industry of Great Britain is the effect of the working of the Coal Mines Act, 1930. This Act, which received the Royal Assent on Aug. 1, 1930, contains five parts: (1) production, supply and sale of coal; (11) the reorganization of the coal-mining industry; (111) hours of work; (IV) the Coal Mines National Industrial Board; (V) general. The first three parts are of major interest and discussion can be confined to them. Part I.—Production, Supply and Sale of Coal Under Part I of the Coal Mines Act, 1930, provision is made for central and district schemes to regulate the production, supply and sale of coal by the fixation of standard tonnage, quota and minimum prices. By Nov. 1, 1930, all the district schemes came into force with the exception of that for Scotland, where the majority of the coal-owners did not see their way to accept the amendments to their draft scheme demanded by the Mines Department. A compulsory scheme for Scotland was thereupon prepared by the Mines Department and put into force on Nov. 24, 1930. It is administered by the coal-owners of the district. The essence of the schemes is the allocation of tonnage for each district by a Central Council, and the allocation of quota for each pit in a district by an Executive Board for that district. Up to Dec. 31, 1930, the various bodies of coal-owners engaged in administering the schemes were employed in work preliminary to their full operation. Standard tonnages had to be determined and coals had to be classified. In consequence, it was not found possible to put the regulation of output into force until Jan. 1, 1931. The determination of minimum prices proved to be an even longer process, and only in a few districts were minimum price schedules operative during the first quarter of this year. The working of the schemes during the March quarter, 1931, has been reviewed in an official publication by the Mines Department,' which can be summarized as follows:

Jan 1, 1932

By E. W. Henderson

Oil and gas development in Utah in 1936 added nothing of importance to the commercial possibilities of the state and consisted principally of efforts to reach objectives in wildcat wells started prior to 1936. Leasing activity on structures having oil and gas possibilities in beds of Pennsylvanian age or older followed announcement by the Standard Oil Company of California that a test of beds of Mississippian age would be made on the San Rafael structure. DRilling Clay Basin, Dagget County.—The Mountain Fuel Supply Co. completed a third well, sec. 16, T. 3 N., R. 24 E., on a flank of this structure. Total developed open flow of the field is approximately 50 million cubic feet and sufficient reserve has been established to warrant construction in 1937 of a pipe line connecting with the Salt Lake City-Ogden line. San Rafael, Emery County.—The Standard Oil Company of California started a wildcat test in sec. 22, T. 23 S., R. 11 E. Circulation was lost in a water-filled cavity, in dolomitic limestone, below 2185 ft. and the hole conditioned as a water supply for drilling a second test in sec. 27, T. 23 S., R. 11 E. The Carter Oil Co. in 1921 drilled a well in sec. 24, T. 23 S., R. 11 E., which was abandoned at a depth of 3035 ft. after testing at least a part of the Pennsylvanian section. Czsco, Grand County.—Drilling operations at the Utah Sout.hern Oil Company's test in sec. 33, T. 22 S., R. 22 E., continued throughout the year. Information obtained by means of a seismographic survey of the area indicated that beds of Pennsylvanian age would be found at approximately 2500 ft. The bottom of the hole at 6300 ft. is believed to be in beds of Pennsylvanian age but positive determination has not been made froin the drill cuttings. Green River, Grand County.—Test of Glen Ruby et al., sec. 34, T. 21 S., R. 16 E., was abandoned at 2627 ft. as a dry hole after drilling into Permian Kaibab limestone. Shows of oil and gas were reported and a flow of carbon dioxide gas under low pressure encountered.

Jan 1, 1937

By F. G. Tryon

This paper treats only of the practicability of introducing a standard classification into the records of production and distribution of coal which we try to keep in the Bureau of Mines. From the point of view of gathering and analyzing statistics, the requirements of a satisfactory classification are that it shall be so definite as to eliminate the factor of arbitrary judgment, that it shall be reasonably simple and, finally, and most important, that it shall be understandable to the trade. In other words, to be woven in the statistical record it must be adapted to the raw material which flows in from the 7000-odd mines that produce the coal. The success of any scheme of classification, from the point of view of use, will depend largely on the degree to which it utilizes the accumulated experience of the trade and employs as far as may be possible the accepted trade designations. The experience of the Tidewater Coal Exchange during the war would be an excellent point of departure for a use classification of the coals of the Eastern Appalachians. Although the exchange long since passed out of existence, coal is still quoted and sold by the old pool numbers, and they have shown rather extraordinary vitality. Some years ago, in the Geological Survey, the experiment was tried of getting operators to classify their own coal by offering them a list of standard designations on the annual statistical questionnaire. The results were more amusing than informative. What with the confusion in terminology and the natural temptation to put one's best foot foremost, there was a general tendency to grade up the quality. Floods of semi-bituminous coal flowed in from many sources, millions of tons from districts where not a pound of that quality has ever been produced. The producers of semianthracite in Arkansas almost without exception would report their product as anthracite and their neighbors in the little Paris field, producing a fine blocky house coal averaging about 17 per cent, volatile, would say, "Our coal isn't anthracite; it's a semianthracite." Finally we discontinued the publication of those data as being more misleading than helpful.

Jan 1, 1930

By G. C. Rauch, T. H. Courtney, J. Wulff

The superconducting behavior of Nb-Ti alloys containing 40 and higher wt pct of Nb and variable oxygen content was studied as a function of thermomechanical processing. Critical current density (Jc) us applied transverse magnetic field (H) data were obtained for 0.010 in. diam wires at 4.2° Kin steady fields up to 120 kOe. The precipitate responsible for increase in Jc in each of the alloys studied was related to niobium and oxygen content. In alloys containing 40 to 60 wt pct Nb with less than about 1600 ppm of oxygen, w precipitation in the range 350° to 450°C appears to be responsible for the maximum value of Jc observed. In alloys of higher oxygen content (-2500 ppm), the oxygen-enriched a phase which precipitates in the temperature range 450° to 550°C is a more effective fluxoid pinner. Maximum Jc in low oxygen (350 ppm) 80 wt pct Nb alloys was achieved by 600°C aging heat treatments. Measurements of resistive critical field also reflect the changes in composition accompanying precipitation in these alloys. It is well known that the superconducting critical current density, Jc, of solid solution superconducting alloys can be increased by precipitation heat treatments.1-4 The precipitate, to serve as an effective superconzlucting fluxoid pinner and increase Jc, must be of proper size and spacing.' Its electronic properties must also be different from those of the matrix.6 As in age-hardenable systems, optimum temperature and time of aging are dictated by the composition and history of the particular solid-solution alloy under consideration. The alloy diagram of Ti-Nb7-9 shown in Fig. 1 is typical of ß-stabilized Ti alloys. Precipitation to achieve high Jc in Ti-Nb and Ti-Ta alloys is usually carried out in what is believed to be a two-phase a + ß region.1,2,4,10 Previous work on Ti-Nb4,11 and on other ß-stabilized systems such as Ti-V, Ti-Mo,12-14 has shown, however, that the first precipitate to appear is not necessarily (Y. Under specific conditions the meta-stable w phase is precipitated instead. A further complication arises in such alloys from the strong influence of contained oxygen on the phase stability and on the kinetics of precipitation.15,16 The superconducting critical current density of Nb-Ti alloy containing less than 36 wt pct Nb has been studied by Vetrano and Boom1 and Kramer and Rhodes.4 The most effective aging temperature was found to be about 425°C; fluxoid pinning was attributed to the precipita- tion of a by Vetrano and Boom and of w by Kramer and Rhodes. Although the latter workers used recrystal-lized material and the former cold-worked, studies carried out in our laboratory lead us to believe that the type of precipitate responsible for increased Jc is unaffected by prior cold-work.17 That other types of precipitates may also be effective, especially in higher oxygen-containing alloys, has been demonstrated by Reuter, et al.2 in this laboratory with the aid of electron microscopy. Reuter et al. found that at an aging temperature of 600°C, fee-TiO is precipitated, resulting in high values of Jc. Even higher values of Jc were observed after heat treatment at 500°C, but the precipitate could not be indexed as fee-TiO. Whether the precipitate was oxygen-rich w or a could not be clearly distinguished. The work nevertheless indicates that appreciable amounts of oxygen alter the nature of the phases precipitated at different temperatures, at least in alloys containing more than 36 wt pct Nb. Since such compositions are more readily worked into suitable wire than lesser niobium content alloys, it was decided to study the response to aging of the alloy compositions reported in the present paper with the hope of clarifying the effect of composition on the precipitation processes responsible for high values of Jc. I. EXPERIMENTAL Nb-Ti alloys containing 40, 50, 60, and 80 wt pct Nb were prepared by are-melting 35 g ingots of iodide crystal bar titanium and electron-beam melted niobium.

Jan 1, 1969

By H. R. Peiffer

Hardening of soft metals can be accomplished by dispersing finely divided hard particles in them. The dispersing of finely divided alumina in silver in the presence of oxygen yields a high strength material which is unusual in that its mechanical properties above the melting point of the continuous Ag-O alloy matrix are similar to other solids. The tensile strength is studied for two of these alloys, one of which contains 15 pct by weight alumina and the other 20 pct by weight alumina. The average fracture strengths above 960°C of these alloys were found to be 0.4 x106 dynes per sq cm and 3.8x106 dynes per sq cm respectively. The strengths appenred to be independent of temperature above 960° C. The creep behavior of the 20 pct alumina material was studied above 960°C. The initial creep rate, 6 , of this material can be represented by where s is the applied stress and E the activation energy for the process. This energy is of the order of 1.7 to 2.1 ev. HARDENING of soft metals by the addition of finely divided, hard particles has resulted in the production of materials with excellent creep resistance and with inhibited recrystallization.' It has been demonstrated that such composites have useful strength up to temperatures very near the melting point of the soft metals, but one might expect that the strengthening by the dispersed particles ceases to be of importance above the melting point of the softer phase. This, however, is not so.2 In this paper the strengthening of a liquid Ag-O solution by the presence of dispersed alumina is discussed and experimental data concerning the mechanical properties of such a material at temperatures above 960°C presented. EXPERIMENTAL PROCEDURE Specimens were prepared using powder metallurgical techniques. Finely divided silver oxide was mixed in the appropriate proportions with "Linde B" alumina. For these experiments the specimens contained 15 or 20 wt pct alumina in pure silver.* These alloys were used in these experiments since they were the ones that could be handled readily enough to yield experimental data. Silver oxide was used in preference to silver because it is readily available in a very finely divided form and because the presence of excess oxygen in the silver is important to the properties2 of the material. The powders were mixed wet, using alcohol as the medium, in an ordinary food blender until a uniform mixture was obtained. They were then dried and heated to reduce the silver oxide to silver. Only a fraction of the finely divided silver remains unoxi-dized upon removal from the oven since the finest particles of silver oxidize immediately upon contact with air. The remaining fine silver served as a binder during pressing. The mixture was then pressed at 20 tons per sq in. into shoulder-grip (reduced section 1/4 in. by l/4 in. by 1 1/4 in.) and rectangular bar specimens (l/4 in. by 1/4 in. by 2 in.). The green specimens were heated very rapidly in a globar furnace to 1000°C, held at temperature untic they had reached theoretical density and then furnace cooled. The strength of the two compositions at temperatures above 960 °C was determined by pulling shoulder grip specimens inside a furnace mounted on a tensile machine. Specimens were gripped by means of wires wrapped around the shoulders of the specimen. Temperatures were measured by means of a chro-mel-alumel thermo-couple placed in the vicinity of the specimen. Control of temperature (within ±°15C) was accomplished by means of a Weston Recorder-Controller. Before loading, specimens were held at temperature for approximately 15 min in order to insure uniform specimen temperature. The low loads were measured by a special load cell designed by Baldwin Lima Hamilton. All testing was performed on a FGT testing machine of the same com-pany. Creep studies were performed in bending utilizing rectangular specimens of the 20 pct alumina alloy. Specimens supported at both ends by knife edges of inconel were placed in a globar furnace, heated quickly to temperature, and the deflection of the beam measured optically as a function of time. The weight and size of the specimen were predetermined and the maximum stress on the beam calculated from

Jan 1, 1962

By R. W. Fountain, John Chipman

The solubility of nitrogen in Fe-B alloys (0.001 to 0.91 pet B) is determined by the Sieverts' technique for temperatures of 950° to 1150°C. The activity coefficient of nitrogen is decreased by boron. The three-phase equilibrium between ? iron, BN, and gas is established and also the four-phase equilibrium between iron, BN, Fe2B, and gas. The above equilibria are calculated for a iron. The relation of these data to hardenability and strain aging of boron-treated steels is discussed. BORON additions are known to enhanbe the hardenability of heat-treatable steels and to assist in the control of strain aging in sheet steel for deep drawing. The increase in hardenability is explained by the theory that adsorption of boron on austenite grain boundaries reduces their free energy and thus retards ferrite and upper bainite nucleation.l,2 Digges and Reinhart3 have shown that the full effectiveness of boron in commercial steels is achieved only when strong nitride formers such as titanium and zirconium are also present. The influence of nitrogen on eliminating the boron contribution to hardenability was also demonstrated by Shyne and Morgan.4 These workers prepared Ni-Mo steels containing either nitrogen or boron or nitrogen plus boron. The nitrogen-plus-boron steels showed the lowest hardenability which was attributed to the presence of stable nucleating particles, presumably nitride. Morgan and Shyne5-7 have shown that boron in the amount of 0.007 pet will completely eliminate strain aging due to nitrogen in low-carbon, open-hearth steels. In addition, by proper control of the boron additions, a rimming steel can be produced. Since the effectiveness of boron on hardenability and eliminating strain aging is influenced by the amount and distribution of the nitrogen in the steel, the present study was. undertaken to determine the influence of boron on the solubility of nitrogen in iron. EXPERIMENTAL PROCEDURE The solubility of nitrogen in Fe-B alloys was measured by the method of Sieverts, which consists of determining the amount of gas dissolved by the metal in a constant volume system. The apparatus employed in this investigation and the experimental details have beendescribed previously.B AMcLeodgage was added to the apparatus to allow measurements at very low pressures. The alloys were melted at reduced pressure in a basic-lined induction furnace using electrolytic iron and ferroboron. Ferroboron was added after the primary deoxidation of the iron with carbon. Since it was difficult to attain a constant low level of oxygen by this procedure, silicon was added after the carbon deoxidation and prior to the ferr obor on addition. The alloys were castas 2-in. sq ingots, heated in argon at 1050loC, and forged to 1/4-in. plate. After forging, 1116 in. was machined from each side of the plate to remove any possible contamination, and it was then cold-rolled to 0.010-in. sheet. The sheet was cut into approximately 1/4-in. squares and pickled in an inhibited H2SO4 solution to ensure a clean surface. In the case of the boron alloys, a hydrogen treatment could not be used for surface cleaning because boron losses resulted. The composition of the alloys is given in Table I. For a solubility determination, a 75-g sample was inserted in a quartz tube and sealed in place in the apparatus. The entire system was evacuated at room temperature and leak tested for 24 hr. If no leaks were observed, the system was heated to the temperature of measurement and again leak tested for 24 hr. If no leaks were detected, the hot volume and solubility determinations were begun. The hot volume was determined at a constant temperature for each run by admitting successive amounts of argon and recording pressure vs volume, which, in all cases, resulted in a straightline relationship. The argon was then removed and the procedure repeated with nitrogen. Successive additions were made until the desired nitrogen content of the metal and equilibrium pressure of the system were obtained. The

Jan 1, 1962

By C. S. Finney, John Mitchell

The growing popularity in the United States of the vertical-flue even was emphasized when in 1905 the United States Steel Corp. chose the Koppers oven as the type which best suited their requirements. Heinrich Koppers was born on November 23. 1872. at a small farm in Walbeck near Geldern on the lower Rhine. When young Koppers was eight years old, however the family moved away from the farm to the industrial city of Bochum in the Ruhr. Here Koppers attended public school and subsequently served an apprenticeship to a tinsmith before taking a job as a lathe operator with a local steel company. He had ambitions to be much more than a machinist, however, and used his week-ends and evenings to improve his theoretical background by taking courses at a vocational-training school in Bochum. After winning the highest honor the school could bestow (the silver Staats-medaille), Koppers went on to continue his education at the Rheinisch-Westfalische Hüttenschule in Duisberg. One of his teachers there, Fritz Wüst who later became a professor at the Technische Hochschule at Aachen, recognizing Koppers' unusual abilities, predicted for him a great future. In 1894 Heinrich Koppers joined the firm of Dr. C. Otto and Co. in Dahlhausen, and in 1899 while superintendent of the Mathias Stinnes mine he built his first battery of ovens for Hugo Stinnes, the German industrialist. Two years later he started his own organization, and in 1902 he made Essen his headquarters. It was to Essen that a group of engineers from the United States Steel Corp. went in 1906 with an invitation to Koppers to design and supervise the construction of four batteries of ovens at the Joliet works of the Illinois Steel Co. Each battery was to consist of 70 ovens. Arriving in the United States in 1907, Koppers established a branch of his firm in Joliet, and construction began. The first battery was fired on July 27, 1908. Rugged and simple, these ovens incorporated basic design features which were to make the Koppers oven and its future modifications the choice of a very large segment of the by-product coking industry of America. The 280 ovens at Joliet were 35 ft long, 8 ¾ ft in height, and tapered from 21 to 17 in. The total daily capacity of the four batteries was 2240 tons of coke. The ovens were of the new cross-regenerative type; that is, instead of longitudinal regenerators serving an entire battery, as in the older Koppers ovens, cross regenerators for each separate oven were employed. Fuel gas was supplied from the side of the battery through ducts in the brickwork known as gun flues, which reached to the center of the battery under the vertical heating-flues. Removable, ceramic gas-nozzles fitted at the top of each gun flue helped to insure good control over the distribution of the fuel gas, and uniform heating conditions were also promoted by regulating the air supply to, and the suction in, each heating flue. A different refractory w& used for each battery. One was built of American silica brick, one of American quartzite, and two of imported German quartzite. The installation at Joliet proved to be very successful, and in 1911, 490 additional' Koppers ovens were built for the Illinois Steel Co. at the great new steelworks at Gary, Ind. By 1912 the H. Koppers Co. had established its headquarters in Chicago and was rapidly extending its business to include construction for such iron and steel companies as the Woodward Iron Co. at Woodward, Ma. (80 ovens in 1912); the Tennessee Coal, Iron and Rail- road Co. at Fairfield, Ala. (280 ovens in 1912); the Inland Steel Co. at Indiana Harbor, Ind. (86 ovens during 1913 and 1914) ; and the Republic Iron and Steel Co. at Youngstown, Ohio (68 ovens in 1913). In 1914 a group of men in Pittsburgh bought a major shareholding in the H. Koppers Co., and moved the headquarters of the organization from Chicago to their own city. Under its new management the company was highly successful in obtaining a large share of the contracts for by-product installations built during World War I. In 1917 the remaining German interests in the company were

Jan 1, 1961

By Jun Hino, P. G. Shewmon, P. A. Beck

THE investigations of Crussard,' of Guinier and Tennevin,' and of Dunn and Daniels," indicate that the subgrains formed in a cold worked and annealed metal are capable of growing at each other's expense during annealing, if the temperature of annealing is sufficiently high and the time is long enough. The results of Dunn and Daniels are particularly convincing in showing that subgrain growth is essentially the result of the free surface energy associated with the subboundaries. In subgrain growth, as in ordinary grain growth, energy is gained as a result of the decrease in total subboundary surface area per unit volume. Recently, Wood and Scrutton4 found that the rate of subgrain growth upon annealing increased very considerably, if simultaneously a creep strain was applied to the specimen at a low strain rate. Working with 99.98 pct pure fine-grained aluminum, these investigators found that the continuous X-ray diffraction back-reflection rings of material strained at room temperature remained continuous after heating for ten days at 250 °C. However, when heated at the same temperature under a stress of 1000 psi even for only three days, the formerly continuous X-ray diffraction rings broke up into numerous dots, which were fairly clearly separated from each other. The continuous X-ray diffraction rings were interpreted as indications of a very small subgrain size, not resolved by the X-ray diffraction method used. The breaking up of the continuous X-ray diffraction ring during annealing under stress was taken as an indication of a great increase in subgrain size, so that the individual subgrains could then be resolved. The effect of simultaneous strain at a low strain rate in accelerating subgrain growth, discovered by Wood and Scrutton and designated by them as "cell growth," is of fundamental importance. The experiments described in this note were carried out in order to confirm Wood and Scrutton's results by direct metallographic observation. Also, information was sought as to the minimum creep strain necessary to produce this effect. A fine grained high purity aluminum strip was prepared by alternate 33 pct rolling and annealing treatments for 1 hr at 350°C. Specimens cut from this strip were subjected to a relatively fast creep strain of 7.2 pct in 3.5 min at 300°C under a constant load initially corresponding to 1185 psi. The subgrains set up were large enough (about 0.015 to 0.03 mm) to be clearly observed (Fig. 1) at X200 magnification with polarized light, after electrolytic polishing and anodic etching, producing a fine oxide film." The corresponding X-ray diffraction pattern is shown in Fig. la. After the fast creep strain treatment a portion of the specimen was subjected to a creep strain of 8.3 pct in 44 hr at 350°C under a constant load initially corresponding to 320 psi. Another portion, annealed under the same conditions, but not strained, served as control specimen. The subgrain size of a typical area of the specimen annealed under strain and of the one annealed without strain is shown in Figs. 2 and 3 (X-ray diffraction patterns, Figs. 2a and 3a). Annealing without strain produced clearly observable subgrain growth (subgrain size: about 0.03 to 0.05 mm). The effect of simultaneous strain was to increase greatly the rate of subgrain growth (resulting in a subgrain size of approximately 0.05 to 0.13 mm), in accordance with Wood and Scrutton. In another experiment, the effect of the amount of simultaneous strain was studied. The initial subgrain structure was set up by fast creep, as described previously. The specimen was then heated at 350 °C under a constant load initially corresponding to 320 psi, as above, for 2.2 hr (0.24 pct strain), and 8.8 hr (0.58 pct strain). Comparison with the corresponding unstrained control specimens by means of X-ray diffraction showed that 0.58 pct strain definitely had an effect, but the effect of 0.24 pct strain was doubtful.

Jan 1, 1953

By D. Akers, R. Dospoy

Introduction The geological processes that form coal can also concentrate trace elements in the coal. For example, the average concentration of arsenic in bituminous coal (20 ppm) is ten times the average concentration found in all the other rocks that make up the earth's crust (2 ppm). Similarly, other elements, such as antimony, cadmium, mercury and selenium, are more concentrated in coal than in the earth's crust. When coal is burned, trace elements can be further concentrated. Although no new constraints on trace clement emissions were placed on the power generation industry under the 1990 Clean Air Act Amendments, the act does mandate a three-year study of air toxics. Any new regulations aimed at electric utilities as a result of this Federally-mandated study will almost assuredly be very costly-an estimated $1 billion per year. Many trace elements in coal are associated with mineral matter. For example, arsenic is commonly associated with pyrite, cadmium with sphalerite, chromium with clay minerals, mercury with pyrite and cinnabar, nickel with millerite, pyrite and other sulfides, and selenium with lead selenide, pyrite and other sulfides (Finkelman, 1980). There are also cases in which some of these elements are organically bound. Just as both organic and pyritic sulfur can be found in the same coal, the same trace element may be both organically bound and present as part of a mineral in the sane coal. Physical coal cleaning techniques are effective in removing mineral matter from coal and can potentially remove at least some of the trace elements associated with specific minerals, thereby reducing the release of these elements into the atmosphere. Conventional coal cleaning to remove trace elements As part of a project funded by the Electric Power Research Institute, CQ Inc., a wholly-owned EPRI subsidiary located in western Pennsylvania, has demonstrated that large reductions in the concentration of many trace elements are possible if conventional coal cleaning techniques are properly applied. Four examples are given in Tables 1 to 4. In each example, the results shown were generated by cleaning the coal at CQ Inc.'s commercial-scale cleaning test facility. Cleaning results for Upper Freeport Seam coal from Northern Appalachia are provided in Table 1. Data are presented in the table in two ways: as a weight-based concentration (parts per million) and as a concentration per heat unit (grams per billion Btu). Grams per billion Btu is analogous to pounds per million Btu, but avoids the use of numbers with many decimal places. The heat-based concentration provides a better measure of boiler impacts, because the increased heating value obtained through coal cleaning reduces the number of tons that must be burned to produce a given thermal output. Reducing the quantity of coal burned reduces the quantity of trace elements entering the boiler. This raw coal is relatively high in several trace elements of environmental concern, including arsenic, cadmium and chromium. Cleaning provided large reductions in the quantity of arsenic, barium, cadmium, chromium, fluorine, lead, mercury, nickel, silver and zinc. The results for tests with a Powder River Basin coal, Rosebud/McKay, are presented in Table 2. Large reductions in arsenic, barium, cadmium, fluorine, mercury, nickel, selenium and zinc were observed with cleaning. The concentration of chromium increased with cleaning, while lead concentration increased in one test and decreased in another. Table 3 presents test results for Croweburg Seam coal from Oklahoma. Large reductions in arsenic, barium, cadmium, chromium and zinc were obtained with cleaning. Smaller reductions were obtained with lead and nickel, while chromium, fluorine and mercury increased in at least one of the tests. Table 4 presents cleaning test data for Kentucky No.11 Seam coal. In this case, large reductions were obtained with all elements measured. In general, these data indicate that physical coal cleaning is effective in reducing the concentration of many trace elements, especially if they are present in the coal at relatively high concentrations. The degree of reduction achieved is coal-specific, relating in part to the degree of mineral association of the specific trace element and the degree of liberation of the trace element-bearing mineral. The extent of trace element removal also depends on the method of cleaning the coal. Figure 1 is a washability plot, by size fraction, of arsenic vs. ash content for Upper Freeport

Jan 1, 1994