Search Documents

By Wallace Pratt

INTRODUCTION IRON-ORE deposits in the Philippine Islands became the subject of official record as early as 1664. Undoubtedly iron ore was known and recognized by the Filipinos long before the earliest Spanish records. It is even possible that the Filipino practice of smelting iron ore is, like the native copper smelting, older than the Spanish conquest of the islands. The first records have to do with the magnetite-hematite ores near the towns of Santa Inez and Bosoboso in Rizal Province, from 15 to 20 miles east of Manila. The magnetite-hematite ores of Bulacan were exploited in 1783. Similar ores near the town of Mambulao in Camarines Province yielded a number of specimens to be exhibited in Spain in 1834. With the exception, then, of the lateritic iron ores on the eastern coast of northern Surigao, the true nature of which was not recognized until 1914, the important iron-ore deposits of the Philippines had all been discovered before the islands came under the dominion of the United States. Indeed, in the Spanish documents relating to the history of iron mining are statements which, if their accuracy be not questioned, leave us in the Philippines today with much less iron ore than the Spaniards found. To quote, for example, a report submitted to the Superior Government in Spain in 1835 by one of its emissaries, Don Lorenzo Calvo: "The Philippine Islands, most excellent Sir, possess iron and exhibit it in nearly every known mineralogical combination, and in such abundance that the cordillera of the island of Luzon, from Montufar Point in San Bernardino Straits to Cape Bojeador, is composed of no other mineral than iron, its ranges, of the third order, being in content and structure totally iron of the best quality, the more valuable in that its combinations are such as to facilitate its fusion and to render its reduction to metal simple."

Jan 2, 1916

By W. M. Albrecht, M. W. Mallett

The solubilities of hydrogen in titanium and several of its alloys were determined at 600 to 1000°C and pressures of 0.05 to 10µ of mercury. Solubility increases with increasing beta phase in the alloys. Factors found to affect degassing rates are specimen size and presence of thick surficial oxide. Removal of hydrogen by heating in vacuum and in flowing inert atmospheres was studied. Practical curves predicting minimum degassing times are presented. THE presence of hydrogen in titanium and titanium alloys has detrimental effects on the mechanical properties of the metal.'"," The hydrogen content of commercial titanium is sometimes of the order of 200 ppm by weight' and varies with alloy composition. As a consequence, titanium and some titanium alloys as normally processed are sometimes not ductile unless treated to lower the hydrogen content. The best known hydrogen-removal treatment is heating the material in a vacuum. The rate of removal (degassing) at a give temperature determines the duration of the treatment required to attain a satisfactory low hydrogen level.

Jan 1, 1959

By Gilbert Francklyn

The requirements of coals for the manufacture of coal gas, water gas and producer gas will be considered sparately and a short description of each gasmaking process will be given. In this report the term "gas coal" is confined to coals suitable for the manufacture of city gas in horizontal, inclined or vertical retorts. The report does not refer to coke-oven practice.' Briefly, the process of manufacture consists of distilling the coal at high temperature in an externally heated retort out of contact with the air. The products of distillation, consisting of gas, tar, ammonia, etc. are collected and purified. The residue consists of coke, which is removed from the retort at the end of the carbonizing period. To supply the heat required in the process, a portion of the coke produced is converted into producer gas, which is burned under the retort settings. Qualities of Gas Coals The chief qualities that coal must possess in order to be classified as a gas coal are as follows: 1. Gas Yield.—The coal must be capable of yielding gas in sufficient volume and of a satisfactory quality. The yield depends considerably upon the temperature of distillation; a higher temperature will give a larger yield of gas, but the qualit,y of gas (now measured by the British thermal units per cubic foot) will be lower, while a lower carbonizing temperature will give less gas of higher heating value. The true measure of the yield is the number of British thermal units produced in the gas from a given quantity of coal. This number is obtained by multiplying the cubic feet of gas from 1 lb. of coal by the British thermal units per cubic foot of gas; it is called B.t.u. feet per pound. It is found that the

Jan 1, 1930

By Phillip E. Deering, Robert M. Cox

A model pillar study was conducted in which the engineering principles of dimensional analysis were applied to the problem of coal mine pillar design. The paper reviews the theory of similitude as applied to the model pillar study conducted in the investigation. An example solution of a design problem is included to indicate how the results of the study may be used as a first approximation in the design of coal mine pillars. The design of mine pillars for adequate support with minimum loss of valuable raw materials has always presented a problem to the mining engineer. Most often, for lack of a better method, past practice has influenced the design of new mine pillars. This process has always left doubt as to the safety factor of the pillars. The work presented in this paper is an initial attempt toward adapting the engineering principles of dimensional analysis to the problem of pillar design in underground mines. The use of the dimensional analysis technique is advantageous because all the variables associated with the problem are considered, and by systematic analysis the relative influence of each variable is determined. The model material utilized in this study was taken from the Helena seam of the Cahaba coal field located in central Alabama. The research study was sponsored by The Southern Electric Generating Co. as part of an over-all rock mechanics investigation of the Helena seam area. THEORY OF SIMILITUDE Model analysis is used extensively in engineering today, particularly in the solution of design problems that defy the classical methods of analysis. Such problems arise when materials with a nonlinear stress-strain relationship are involved, when geo- metric boundaries are difficult to define in simple form, when strains become large, or when partial failure occurs. All of these difficulties usually exist in pillar design problems. Those principles which underlie proper design and construction of models, and the interpretation of test results, comprise the theory of similitude. That is, the theory of similitude includes a consideration of the conditions under which the behavior of two separate entities or systems will be similar, and the techniques of accurately predicting behavior of one from observation of the other. The theory of similitude may be developed by dimensional analysis. Dimensional analysis, as a powerful analytical tool, is developed from a consideration of the dimensions in which each of the important quantities involved in a phenomenon is expressed. It is based on two axioms: 1) Absolute numerical equality of quantities may exist only when the quantities are similar qualitatively. 2) The ratio of the magnitudes of two like quantities are dependent on the units used in their measurement, provided that the same units are used for evaluating each. Dimensional analysis, developed from these two axioms, differs from other types of analysis in that it is based solely on the relationships that must exist among the pertinent variables because of their dimensions, rather than on the relationship of natural laws. In itself, dimensional analysis ~rovides qualitative, rather than quantitative relationships, but when it is combined with experimental procedures, it may be made to supply quantitative results and accurate prediction equations. APPLICATION OF THEORY The design of an adequate mine pillar requires the determination of a design equation and the selection of a dimensional system with which to work. Since force plays an important part in the design of mine support, the FLT (force, length, time) system has been used. The factors involved in the dimensional analysis of mine pillars and their dimensions are: A = cross-sectional area L Cp = design strength FL- E, = tangent modulus of elasticity FL

Jan 1, 1969

By J. B. Newkirk, A. H. Geisler

The alloy Cu4Pd has a disordered face-centered-cubic structure when quenched from temperatures between 478ºC and the melting point (about 1100°C). Below 478ºC an ordered phase is stable. The results of a Debye-Scherrer X-ray analysis indicate that the ordered phase has a tetragonal unit cell described by the space group C24h — P42/mt with 2 Cu in 2a, 2 Cu in 2f, 4 Cu in 4j (x = 0.2, y = 0.6), 4Pd in 4j (x = 0.4, y = 0.2), and 8 Cu in 8k (x = 0.1, y = 0.3). The orientation relationship between the face-centered-cubic phase and the ordered tetragonal phase is given by: [100],,. // [130]al,. COO1Ia.d.//COO1I,,.. • The behavior of Cu,Pd is typical of ordering alloys except that the transformation is very sluggish. The increase in hardness and the microstructural and X-ray diffraction effects are interpreted in terms of coherency strains caused by the ordering. AN anomalous construction in the Cu-Pd phase diagram (Fig. 1) was reported in 1939 and has been allowed to stand without further published attention since that time. The odd figuration about the composition 10 to 27 atomic pct Pd is derived mostly from the work of Jones and Sykes.1 Evidently several features of this binary system require further study if the constitutional forms are to be well understood. The present paper includes a study of one of these features, that is, the crystal structure of a single ordered alloy containing nominally 20 atomic pct Pd. This choice of composition was suggested by the work of Harker and associates who determined the structure of Ni4Mo2 and Ni4W.3 The nature of the ordering process in Cu4Pd was studied also by observing the hardness, microstructure, and Debye-Scherrer patterns of specimens which had been aged at various temperatures after quenching from an initial disordering treatment. Experimental Methods A 20 gram ingot of Cu4Pd was made by melting spectrographically standardized copper from Johnson, Matthey, and Co., and commercially pure (99.5 + ) palladium in an argon-filled quartz tube. Chemical analysis showed that the ingot contained 80.0 atomic pct Cu. The ingot was rolled about 60 pct to a strip 0.060 in. thick and was homogenized for 16 hr at 950°C in low pressure argon. Rods cut from the rolled strip were worked into wire 0.015 in. in diameter, and specimens for hardness and microscopic examination were cut from the remaining strip. All specimens, with the exception of some of the wire, were given an initial disordering treatment by heating for 16 hr at 950°C, followed by water quenching. A 10 cm length of as-drawn wire was water quenched after being held in a temperature-gradient furnace4 for 89 days. Room-temperature Debye-Scherrer photograms were then made at points along the wire to determine the temperature below which the ordered phase was stable. Although the accuracy of temperature determination in the gradient was only about ±10 °C, the temperature gradient was sufficiently gradual that the sensitivity was much better and locations which had differed by as little as 1°C could be distinguished. An analysis of the crystal structure of the well ordered alloy was made by X-ray diffraction using a specimen cut from this wire. The change of Debye-Scherrer pattern as ordering progressed was studied by using isothermally aged samples of initially disordered wires. The wires were sealed under low-pressure argon in small quartz tubes for heat treatment. After the aging treatment, the tubes were quenched in water and photograms were made at room temperature in a 10 cm diam camera using filtered Cu kX. (A = 1.540511) Hardness was measured on a Vickers hardness tester using a 10 kg load and 2/3 in. objective lens. Reported values are the average of at least three impressions made on flat specimens 0.060 in. thick. After the hardness of a heat-treated sample had been measured, it was resealed in low-pressure argon and returned to the furnace for continued aging at the same temperature. In this way, two samples served for all aging times at each temperature. Hardness specimens which had been aged 500 hr or more were used for metallographic examination after the final aging treatment. A dilute potassium-dichromate etching solution was used.

Jan 1, 1955

By S. F. Shaw

In 1913, the Tiro General mine, at Charcas, S.L.P., Mexico, which had been making from 125 to 150 gal. of water per min., was allowed to become flooded, after all the pumps had been removed, and in 1918 the problem of unwatering it came up for solution. There are two vertical shafts, the Tiro General, 1390 ft., and the San Fernando, 1225 ft. in depth, with five connecting levels between them. The San Fernando shaft had been partly retimbered, while the Tiro General had been newly timbered from the collar to 1090 ft. in depth. It had been possible to place guides in only one compartment of the Tiro General, from the collar to the seventh or 850-ft. level, to which it was necessary to lower the water before station pumps could be installed. Soundings indicated that compartments in the Tiro General were open to 1082 and 428 ft., and in the San Fernando shaft to 471, 488, and 586 ft. The water had risen to a point 140 ft. below the collar of the Tiro General shaft.. Pumping Equipment The steam plant at the Tiro General shaft includes one 300-hp., one 150-hp. and one 100-hp. Erie City water-tube boiler, and two 160-hp. Heine water-tube boilers. All but one of these boilers were supposed to be in good shape, but it was soon discovered that six years of idleness in a climate that is foggy for several months of the year had left them in poor condition. The compressed-air plant comprises one Nordberg cross-compound compressor with piston displacement of approximately 2500 cu. ft.of free air compressed to 96 Ib. per sq. in.; and another Nordberg cross-compound with piston displacement of 1235 cu. ft. of free air, to the same pressure. The main pump station is on the seventh level where had been installed a Prescott pot-valve plunger pump with capacity of 200 gal. per min.; also a Gould triplex plunger pump with capacity of 135 gal. per min., driven by a 6 1/2 by 10 by 12 in. steam engine. From the lower levels, the water had been raised to the seventh level by small station pumps and sinking pumps.

Jan 1, 1920

By M. J. Pool, J. R. Guadagno

THE relative partial molar heats of solution in liquid tin have been determined for phosphorous, arsenic, and antimony at 750°K. This work was carried out as part of an over-all program to determine the heats of formation of the III-V semiconducting compounds. A differential twin-type liquid tin solution calorimeter was used in the investigation. All three elements are endothermic upon solution in tin. The relative partial molar heats of solution go through a minimum value at arsenic. No concentration dependence of the heat of solution was found in the dilute (0 to 2 at. pct solute) solution range investigated. The measured heat effects and the calculated relative partial molar heats of solution at infinite dilution are listed in Table I along with the relative heat contents of the solutes calculated from the data of kelley.1 All of the values are referred to 750°K even though the calorimeter temperature fluctuated by *1°K during the course of the experiments. In this range of temperature change no variations were found which were outside the experimental error. This would be expected since the partial molar heat of solution is in general a very insensitive function of temperature. The limits of error given in Table I represent the standard deviation from the mean. The reported error estimates only apply to the estimated precision of the data and not the accuracy. Systematic errors could be present which would affect the absolute values given. This is especially true in the case of phosphorous and arsenic where vaporization could occur. If this were true, the experimental values reported here would be too high and the true partial molar heat of solution would be less than that given in Table I. Moreover, the heat-content data could be in error and this would also affect the calculated values. The relative partial molar heat of solution of phosphorous at infinite dilution in liquid tin is given in Table I. This value is based on eight drops at

Jan 1, 1965

"For many years it has been known that large bodies of iron ore existed in Iron and Washington counties in Utah. The ore is chiefly hematite—both hard and soft—though some magnetite is found. No definite and complete estimate of the iron ore reserves of the state have been made. The U. S. Geological Survey estimated that 40,000,000 tons of ore were disclosed by development work averaging only 35 feet below the surface of the ore. The ore is found along an area about one and a half miles wide by twenty miles long, and for the most part on the eastern and southern slopes or foothills of Three Peaks, Granite Mountain and Iron Mountain. Later estimates by others have gone as high as ore in sight 164,000,000 tons, probable ore 300,000,000 tons and possible ore 1,000,000,000 tons. Whether this last estimate is too great or not there is sufficient iron ore in Utah to justify the starting of an iron industry.Two companies are now mining iron ore in Utah, the Columbia Steel Corporation and the Utah Iron Corporation. The mine of the Columbia Steel Corporation is at Iron Springs a few miles west of Cedar City. About 650 tons, of ore a day is being shipped to the blast furnace at Ironton. The ore is mined by the glory hole method. After being drilled it is blasted to the bottom of the several glory holes and is dropped through chutes into cars on the ore haulage level below. It is then hauled by electric locomotives to the crushing plant, where it is crushed to blast furnace size before going to storage bins. Some of the softer ore is brought to the chutes by Fresno scrapers."

Jan 1, 1925

By George Stone

THE stack gases from regenerative furnaces are very seldom utilized for the production of steam. If the temperature of the gases is not higher than 300° C. (572° F.) there is no economy in their use for this purpose, as the amount of available heat is very small and the temperature is so little above that of the steam that the interchange is too slow. With higher temperatures of the waste gases, however, good results can be obtained. At the plant of the New Jersey Zinc Co. (of Pa.) at Palmerton there are a number of return tubular boilers, each 6 ft. in diameter and 20 ft. long, with 96 3.5-in. tubes, which are heated by the waste gases from the spelter furnaces. These furnaces have continuous regenerators heating the air only and the stack gases reach the boilers at a temperature of about 450°. The gas producers for one of these furnaces require 14 tons of anthracite (a mixture of Nos. 2 and 3 buckwheat), and the waste heat from the furnace gives a little more than 42 h.p. in steam. The boilers are not well adapted for the purpose, as they are much too large for the amount of heat going to them and the area of the tubes is not sufficient to take the gas from two furnaces without causing an objectionable amount of back pressure. The plant was built without any idea of using waste-heat boilers, and it was impossible to place the latter as close to the furnaces as they should be. Furnace and boiler are connected by an underground brick flue in which the temperature of the gas drops about 100°, losing 40 per cent. of its available heat. If the .boilers were close to the furnaces the horse power of each would be 70 instead of 42. Even under these unfavorable conditions the boilers have been very advantageous, as one boiler easily supplies the steam necessary for two batteries of producers. With such low gas temperatures the heating surface of the boilers is, of course, not as efficient and the flue areas need to be considerably larger than for coal firing.

Jan 10, 1913

By E. G. Dean

A method of top slicing has been devised at the Miami Copper Co.'s mine at Miami, Aria., which differs radically in some ways from the customary methods of top slicing. The area of that section of the orebody in which top slicing is used is about 800 ft. square. The ore, while for the most part soft, is, nevertheless, considerably harder than the capping. The latter is siliceous, seldom containing any clay or other binding material, and breaks into fine particles so that it runs like sand if given the opportunity. Because of these facts, and because the ore is above the average grade of the mine ore, it has been mined by top slicing. Haulage levels are opened up 150 ft. apart, vertically, with two sub-levels between at 50-ft. intervals, to facilitate the putting up of ore chutes. These sublevels are used during slicing for distributing air in the ventilation system. On the haulage level the drifts are spaced on 50-ft. centers, and raises along these drifts are also spaced on 50-ft. centers, except the incline raises as hereafter noted. The raises are cribbed where necessary. Where the wear will be excessive, 1/4-in. iron plates are spiked to the top of every third set of cribbing, for its protection. When top slicing was first used, an attempt was made to carry a slicing face from fifty to several hundred feet long. Timber and other supplies were brought in through long drifts from an auxiliary shaft. Great difficulty was experienced in keeping these drifts open, the side pressure breaking the posts and the top weight breaking both caps and posts. Furthermore, the men could not work efficiently while these drifts were being repaired. The slicing faces advanced irregularly, due to varying conditions, and in many ways the results were not all that could be desired. It was then decided to divide the slicing area into blocks 200 ft. square and this was later changed to 250 ft. square. At the center of each block a two-compartment raise is put up as a supply raise, the compartments being 2 ft. 6 in. and 4 ft. by 4 ft. 4 in., the smaller being used as a manway. Station sets of 12 by 12 timber with

Jan 1, 1917

By Edwin R. Walker

The old adage, " Necessity is the mother of invention," is fully borne out in the case of the device described in this paper. About four years ago the firm of the writer received instructions from Sir John Hawkshaw, C. E., and I. Wolf Barry, Esq., C. E., to construct and erect three large Guibal fans for ventilating a portion of the Metropolitan and District Underground Railway, of London. On account of the cost of coal and the very limited space for boilers, it was arranged that the fans should be driven by gas-engines. Those who have had experience with Guibal fans will be aware that as each blade or vane passes the lower edge of the shutter a pulsatory action takes place. When the fans above mentioned were set to work, the pulsation or vibration of the immense volumes of air discharged was so great that it caused a corresponding vibration of the window-sashes, doors, etc., of the surrounding buildings; and this was so unpleasant that the shopkeepers and others near obtained an injunction against the railroad company, compelling it to stop one of the fans. The work was by this time out of our hands, and we only casually heard what had taken place, learning also that, in addition to this injunction, another was threatened in the case of the second fan, and that the railroad company had thus far escaped the enforcement of this threat by agreeing to run the second fan at a few short stated intervals only during each day. In considering the case, it occurred to us to incline the lower edge of the shutter, instead of making it parallel with the axis of the fan,. by which means we thought that the waves of air might be broken

Jan 1, 1891

By E. C. Bain, E. S. Davenport

When annealed carbon, or low-alloy, steels are suitably heated the ferrite (alpha iron solid solution) and the carbide, of which they are composed, react together to form a single solid solution of carbon (and other elements) in gamma iron (austenite). This reaction may begin only at a certain minimum temperature called the eutectoid temperature. The first ferrite and carbide thus to react together do so in definite proportions known as the eutectoid composition. With further heating the original constituent that is present in excess is dissolved in the austenite until exhausted. Whether the excess constituent be ferrite (hypoeutectoid steels) or carbide (hypereutectoid steels) the procedure is much the same, and upon slow cooling the homogeneous austenite expels the excess of either (proeutectoid ferrite or carbide) until the eutectoid composition is reached. Thus the reaction upon heating is strictly reversed upon cooling and accordingly an equilibrium diagram of this process may be constructed. Such an equilibrium diagram concerns itself only with the temperatures involved and with the proportions and compositions of the phases developed under conditions that suffice to permit equilibrium. Specifically it has no concern for the type or mode of distribution of these constituents nor with any extra-equilibrium conditions such as undercooling, which is almost universally encountered in metals. Actually, however, of great importance is the sluggishness toward equilibration caused by the not inconsiderable time involved in diffusion. Thus instead of the theoretical transformation point AF, we find for a certain rate of heating or cooling the use of the designations Ar and Ac (transformation temperature found on cooling and upon heating). These figures obviously have no particular meaning except as measured and expressed for a definite heating or cooling rate, and represent the apparent temperature displacement caused by an inadequate time allowance. In this paper are presented the results of a study of the time required for the transformation of austenite to ferrite and carbide at a variety of temperatures and also of the time required for the reaction austenite? martensite at the temperatures at which this reaction occurs instead of

Jan 1, 1930

By Howard M. Graff, Sidney C. Bouwer

The economics of mining has traditionally been viewed quite apart from the economics of blast furnace operations. It was realized, of course, that blast furnaces would operate best with good raw materials, but the shipping grade of ore, for example, was decided by a sort of collective bargaining process between the ore producers and the blast furnace operators. The mine operators had to keep their costs down, and were usually successful in convincing management that the ore in any particular deposit was endowed by nature with a certain iron content and that the mine grade could not be raised beyond a certain economic limit. The blast furnace operators would have liked a better grade, but as long as they were able to make a fairly good showing it was more or less accepted that they had to take the ore as it came. The mine operators were able to ship to the nation's blast furnaces thousands of tons of iron ore that would be completely unacceptable by present-day standards. As late as the early 1950's, the major steel companies were witnessing an actual decline in the iron content of their incoming ore supply as the mining companies mined progressively leaner material and upgraded it only enough to pass competitive market requirements

Jan 8, 1965

By E. S. Davenport

WHEN annealed carbon, or low-alloy, steels are suitably heated the ferrite (alpha iron solid solution) and the carbide, of which they are composed, react together to form a single solid solution of carbon (and other elements) in gamma iron (austenite). This reaction may begin only at a certain minimum temperature called the eutectoid temperature. The first ferrite and carbide thus to react together do so in definite proportions known as the eutectoid composition. With further heating the original constituent that is present in excess is dissolved in the austenite until exhausted. Whether the excess constituent be ferrite (hypoeutectoid steels) or carbide (hypereutectoid steels) the procedure is much the same, and upon slow cooling the homogeneous austenite expels the excess of either (proeutectoid ferrite or carbide) until the eutectoid composition is reached. Thus the reaction upon heating is strictly reversed upon cooling and accordingly an equilibrium diagram of this process may be constructed. Such an equilibrium diagram concerns itself only with the tempera¬tures involved and with the proportions and compositions of the phases developed under conditions that suffice to permit equilibrium. Specifically it has no concern for the type or mode of distribution of these constituents nor with any extra-equilibrium conditions such as undercooling, which is almost universally encountered in metals. Actually, however, of great importance is the sluggishness toward equilibration caused by the not inconsiderable time involved in diffusion. Thus instead of the theoretical transformation point AE, we find for a certain rate of heating or cooling the use of the designations Ar and Ac (transformation temperature found on cooling and upon heating). These figures obviously have no particular meaning except as measured and expressed for a definite heating or cooling rate, and represent the apparent temperature displacement caused by an inadequate time allowance. In this paper are presented the results of a study of the time required for' the transformation of austenite to ferrite and carbide at a variety of temperatures and also of the time required for the reaction austenite ?martensite at the temperatures at which this reaction occurs instead of

Jan 1, 1930

By D. A. Farmen

INTRODUCTION In early 1978, engineering personnel at The Carter Mining Company began using photogrammetry coupled with a computer modeling technique to aid in mine planning efforts. The decision to develop this approach was based on the following needs: 1. A method to accurately capture excavated quantities for reporting purposes, 2. A method to produce accurate up-to-date maps for planning purposes, and 3. A computer-based mine-planning technique that would be compatible with techniques used in the past. The system developed utilizes a photogrammetric contractor to provide thousands of aerially-surveyed data points for input into the computer system. Each month the Rawhide and Caballo mines are flown by the photogrammetric contractor. The terrain of the active pit area is digitized and punched out on computer cards. This information is read into The Carter Mining Company's computer facilities, and an updated two-dimensional topographic grid model of the pit is generated. This surface is used to generate quantities moved during the month, to update isopachs, and to update quantities contained in fixed block progression polygons used for forecasting purposes. The system has greatly reduced the amount of manhours spent in field surveying and provides a useful tool for expeditiously evaluating many different forecast cases. It also provides the

Jan 1, 1983

By R. E. Wagner

MISSOURI's famous lead area, in what is known as Southeast Missouri, is locally termed the "Lead Belt." These deposits are in the Bonne Terre dolomite of late Cambrian age which has a thickness of nearly 400 ft. Underlying this is the La Motte sandstone which varies in thickness from 0 to 400 ft. The La Motte beds are deposited directly on the ancient erosion surface of Pre-Cambrian porphyries and granites of probably Algonkian age. The buried igneous peaks extend up into the Bonne Terre in several areas within the Lead Belt. Overlying the Bonne Terre are shales and siliceous dolomites of late Cambrian and early Ordovician age. Within the Lead Belt these have a thickness of from 0 to 500 ft. The district is bounded in general on the southwest by the Sims Mountain fault, on the northwest and north by the Big River fault, and on the

Jan 1, 1947

By Albert Sauveur

As THE years go by, names of distinguished metallurgists will be added to the list of Henry Marion Howe lecturers, and now and then an illustrious one, for to be chosen to deliver the Howe lecture will be, I do not hesitate to predict, a highly coveted honor. I pray, therefore, your indulgence, if I confess to a feeling of gratification in having been appointed the first of these lecturers. It does not follow, however, that I am losing all sense of proportion and that I have an exaggerated idea of the little I have been able to contribute to our knowledge of iron and steel. Indeed, I fully realize how small were my claims to so great a distinction. I realize, also, that those entrusted with the task of selecting a lecturer were actuated, in coming to a decision, by their knowledge of the long and intimate friendship that had existed between the leader we have lost and myself. For their generous impulse, I thank them from the bottom of my heart; and with becoming modesty, I take up my task as the first Henry Marion Howe lecturer. It would be pleasant and indeed most appropriate to devote this entire lecture to a eulogy of Henry Marion Howe and his work, but how short the time for so large an undertaking and how inadequate my qualifications! On Aug. 28, Sept. 4, 11, and 18, 1875, a series of articles appeared in the Engineering & Mining Journal entitled "What is Steel?" With one exception, these constitute the first professional paper of Henry Marion Howe. That was nearly fifty years ago, three years after graduating from Harvard University. He was then but twenty-seven years old and already his keenly inquisitive mind was actively at work. There is a touch of romance in this young metallurgist who, on entering his. scientific career, destined to be so brilliant and so fruitful, on the very threshold of it, seems to have selected as his motto "What is Steel?" Like a knight-errant of science, he started on his quest for an answer to that question, a quest which was to last forty-seven years and which death only brought to an end. And while thus engaged how many wonderful messages we received from him, each one bringing us nearer to the goal! How illuminating, inspiring and encouraging were those messages! How well-equipped he was to wrench from nature some of the secrets she so jealously guards! How broad his learning and how clear his

Jan 5, 1924

By George D. Graffin.

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 A.D. graphite crucibles were being made in the Haffnerzell district of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still used for the mineral are "Plumbago," meaning leadlike, and "Black Lead." The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it "graphite" from the Greek word "graphein," meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Ceylon (now Sri Lanka) graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite. Physical Properties and Classification Graphite is found in laminated, flaky aggregates disseminated in schistose rocks. It also occurs in veins and exhibits a foliated or fibrous structure. Graphite is a black lustrous mineral that crystallizes in the hexagonal system, with rhombohedral symmetry. The crystals have tabular form and are six-sided; the faces are commonly striated. The flakes have perfect basal cleavage and are opaque. When well crystallized, the flakes have a black metallic luster while the amorphous material is black and earthy, with a microcrystalline compactness. The flakes feel greasy. Graphite is an excellent conductor of heat and electricity. It melts at approximately 3550°C at a triple point under 1250 psi. It sublimes between 3300-3500°C at 14.7 psi. At 3726°C a second triple point occurs at approximately 100,000 atmospheres. Thermal oxidation in the presence of oxygen begins at 300°C and the rate increases with temperature. The three forms of carbon (charcoal, graphite, and diamond) are distinguished by chemical and physical tests. The specific gravity of charcoal is 1.3 to 1.9, of graphite 2.266 g/ cm3 (crystal density), and of diamond 3.5. Graphite has a hardness of 1 to 2 (Mohs' scale). Natural graphite can be divided into three classes: disseminated flake, crystalline vein (fibrous or columnar), and amorphous. Flake graphite is a lamellar form found in metamorphic rocks, such as marble, gneiss, and schist. Each flake is separate, having crystallized as such in the rock. Crystalline vein graphite is found in the form of well defined veins or as pocket accumulations along the intrusive contacts of pegmatites with limestones. The graphite of such deposits is of two types, foliated and columnar. The important Sri Lanka (Ceylon) deposits are vein type. Amorphous graphite is commonly found as minute microcrystalline particles more or less uniformly distributed in feebly metamorphic rocks, such as slates and shales, or in beds consisting practically entirely of graphite. The latter usually are metamorphosed coal seams and carry as much as 80-85% graphitic carbon, while the former, being altered carbonaceous sediments, commonly range from 25 to 60%

Jan 1, 1983

By A. F. Baker, E. R. Palowitch, A. W. Deurbrouck

As air-pollution regulations become increasingly more stringent, increased significance is being placed on the amount of sulfur present in coals used for steam generation. These regulations are aimed at minimizing the pollution of the atmosphere with noxious gases such as the sulfur oxides that are formed and emitted when coal is burned. Two meet these future requirements, a definite need exists to reduce the sulfur content of some of the coals used for steam generation. Reducing pyritic sulfur involves liberating the pyrite from the coal and then removing it. The specific gravity of pyrite is high (5.0) compared to that of coal (about 1.2, mineral-free), and standard coal-washing devices, such as wet concentrating tables, will efficiently remove pyrite particles larger than about 100 mesh. Particles below this size will be entrained in the table water and will be carried into the clean coal product. Techniques such as froth flotation are of little benefit for pyrite reduction because the flotation characteristics of pyrite are similar to those of coal.

Jan 6, 1966

By Albert Sauveur

THE senior author of this paper has expressed the belief that when gamma iron transforms into alpha iron on reaching the A3 point, each gamma grain does not change bodily into one or more alpha grains but that the alpha phase forms first at the boundaries and along the crystallographic planes of the austenite grains.1 To quote: On cooling through the point A, at about 900° C., iron passes from the gamma condition to a. new allotropic form generally designated as alpha. This transforma¬tion, however, is not instantaneous. There are good reasons for believing that it begins at the grain boundaries and along the octahedral planes of the crystals and that it progresses until each grain of gamma iron is changed into a grain of alpha iron, the resulting structure being similar to that of gamma iron. Were it possible to retain at room temperature pure iron but partially transformed, it seems probable that a Widmanstättian structure, or rather, as later explained, a martensitic structure would be observed (Fig. 1), consisting of alpha iron at the boundaries and at the octahedral planes, and of a groundmass of gamma iron. In order to confirm, if possible, the accuracy of that view, a number of experiments were conducted. Polished samples of electrolytic iron were heated in a vacuum, maintained in the gamma range for several hours and quenched in different media. It was hoped by such means to produce and retain on the polished surfaces a pattern which would reveal the mechanism of the allotropic transformation. The samples were placed in evacuated quartz tubes, heated to 1000° C. and held 2 hr. at that temperature. The tubes were then immersed in the quenching bath. Iced brine and liquid air were used first. The polyhedral austenitic structure existing at the time of immersion was very clearly revealed (Fig. 2). This is generally ascribed to iron volatilizing at the grain boundaries.

Jan 1, 1929