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By T. S. Spicer, C. C. Wright

A characteristic property of bituminous coal is that upon being heated the coal becomes plastic, evolves volatile gases, and finally solidifies into coke. This fundamental characteristic is of utmost importance and is utilized in the production of the high-temperature coke upon which the steel industry is so dependent; but from the standpoint of operation in the domestic underfeed stoker this coking tendency seriously interferes with efficient combustion. When the coke formed has too strong a structure, certain difficulties result, such as low rate of burning, slow response to heat demand, and, in extreme cases, extinction of fire. The plastic mass prevents uniform distribution of air through the fuel bed and, with strongly coking coals, large dense pieces of coke are produced which have much less reacting surface than was possessed by the original coal. In both ignition and combustion of solid fuels, the extent of the reacting surface is an accelerating factor. Poor combustion permits a surplus of fuel to accumulate in the furnace because the rate of feed and the rate of combustion are not in equilibrium, and this produces an unbalanced condition detrimental to continued automatic service. In order to bum strongly coking coals satisfactorily in a conventional stoker during the three requisite types of operation—continuous, intermittent and hold-fire, frequent attention is necessary. Domestic stokers are defined by the industry as residential stoker heaters that burn 60 lb. of coal or less per hour. With a few exceptions, these units employ the underfeed principle of combustion in which both air and coal move in the same direction up and through the fuel bed. Domestic combustion equipment has difficulty in meeting the problems presented by the several variations in ash and volatile matter, in ash-clinkering tendencies, in coking properties, and in the particle size of bituminous coals. The work of Bituminous Coal Research Inc. at Battelle Memorial Institute has shown that, of these, coking characteristics and the clinkering tendencies have the greatest effect upon the operation of the conventional clinkering type of stoker. Typical coke formations in a clinkering type of underfeed domestic stoker are illustratcd in Fig. I, which shows (A) the ideal fuel bed obtained with a noncoking or free-burning coal; (B) the type of fuel bed formed with a coal that produces a weak coke; and (C) the type of fuel bed obtained with a strongly coking coal. C is characteristic of the fuel bed developed when the average Pennsylvania bituminous coal is burned in an underfeed stoker of conventional type. It is apparent from these pictures that the formation of coke trees will seriously interfere with the efficient automatic combustion of Pennsylvania bituminous coals.

Jan 1, 1942

By W. S. Potter

The proportions of manganese and carbon in manganese steel are familiar to all…

Jan 1, 1915

By Richard H. Jahns

Such minerals as beryl, lepidolite, sheet muscovite, spodumene, and tantalite-columbite are obtained chiefly from pegmatite bodies that are internally zoned. As shown by examples of such pegmatites from the Southwestern and Southeastern States during World War II, studies of their internal and external structure have value in prospecting and the planning of exploration, development, and mining.

Jan 1, 1951

By D. W. Duncan, A. Bruynesteyn

An ore containing chalcopyrite was microbiologically leached in 6 ft columns at particle sizes ranging from -2 +1 ½ inches, to -3/8 + 3/16 inches. The rate of leaching increased exponentially as the particle size decreased. The controlling factor was the active leaching volume made up of the particle surface area and the depth of penetration of the bacteria and leach liquor into the particle. This volume became an increasingly larger part of the total volume as the particle size decreased. The sample under test leached poorly at larger particle sizes and it was calculated that under commercial conditions, it would produce at best a pregnant solution containing 100 mg/l (0.2 lb/ ton) of copper per 100 ft of dump height.

Jan 1, 1974

By John Henry Harden

This shaft, located in the northern anthracite coal-field about 2300 feet southwest from the court-house at Wilkes-Barre, in the County of Luzerne, Pa., is the property of the Lehigh & WilkesBarre Coal Company. The sinking and cribbing to the solid rock (see isometrical view on Plate IX) was conducted by Mr. W. W. Kenrick. Dimensions of the earthwork to the foundation of the cribbing, 51' 2" long, 17' 4" wide, 31' deep. Total amount of excavation in cubic yards, 998.5. Dimensions within the permanent cribbing, 45' 4" long, 11' 16" wide, 31' deep, divided into six parts by buttons 8" x 12", each division, 7' x 11' 6". Permanent cribbing 12" x 12"; temporary cribbing 8" x 10" ; backing, 3" thick ; clay puddle to exclude surface water, 12" thick; conductors, 8" x 5"; lining, 1" thick from top to bottom of the shaft. In the latter part of the year 1871, Mr. H. Murray & Son contracted with the company for the continuation of the work at the rate of four hundred dollars per yard in depth, to a point 100 feet below the Hillman seam of coal; for the succeeding 100 feet the price to be increased twenty-five dollars per yard, and so on until the bottom rock of the Baltimore seam of coal was found. The size of the shaft within the cribbing timbers is 45 feet 4 inches by 11 feet 6 inches, having six divisions of equal dimensions, 7 feet by 11 feet 6 inches, giving room for what is known as the "standard diamond " car, whose capacity when level full is 100 cubic feet, but when loaded by the miner 4 inches above the top contains 112 cubic feet." Two divisions of this shaft are intended for hoisting coal from the Hillman seam, two from the Baltimore seam, one for ventilation, and one for pumps. The works were planned for two pairs of direct-acting, high-pressure engines, twenty-four boilers, and for an estimated output of 2500 tons of coal per day from the two seams.

By K. I. Savage, S. C. Sun

This paper describes a process developed to recover coal, clays and pyrite from coal wastes. The process consists of fine grinding followed by coal and pyrite flotation which leaves the clays in the flotation pulp. A bituminous coal refuse containing 10% sulfur and 30% carbonaceous material was treated by this method to yield a coal product containing 4% sulfur, 10% ash; a pyrite product containing 45% sulfur (84% FeS2), 1% carbonaceous material; and a clay product containing 2% sulfur (3.5% FeS2). The coal yield was about 89%. The pyrite yield was about 77%. The process steps may be entirely flotation, or gravity separation (hydrocycloning) may be used to increase the pyrite : coal ratio in the flotation feed. Cost estimates for the process show a profit of $2.28 per ton of low pyrite grade refuse, but these do not include labor, maintenance, overhead and plant depreciation. The development of this process consisted of three parts: (1) exploratory tests, (2) op-timazation tests and (3) confirmatory tests. The objectionable qualities that sulfur imparts to coal have been commented upon from early times, and they have become more objectionable as the uses of coal have grown. In whatever form coal takes — raw, carbonized or gasified —the sulfur content remains objectionable, and therefore its compounds are removed as completely as possible. It has long been known that sulfur occurs in coal in different forms. In 1861, sulfur was said to exist in the state of sulfuric acid in combination with a base; in combination with iron as iron pyrites; as bisulfides of iron; and in combination with the organic elements of coal.' Pyritic sulfur is a term loosely used to cover the sulfur associated with iron in its various forms. The mineralogically recognized forms are pyrite (FeS2), pyrrhotite (Fe 1-x S) and marcasite (FeS2). The particle sizes of pyrites vary widely. Isolated grains of marcasite smaller than 15 microns have been found disseminated through coal.2 Hair-like "veins" of pyrite filling cracks in vitrain have been found. At the other extreme, lumps or nodules of pyrites large enough for removal by hand picking have been encountered. Organic sulfur, unlike pyritic sulfur, does not exist as discrete particles, but is instead intimately associated with the coal structure and thus it is impossible to remove it or reduce its concentration by physical or mechanical means.2 In the preparation of coal for its various markets, the pyrite minerals (pyrites) are separated from the raw coal feed. This separation process concentrates the pyrites in the tailings or other waste products. It would be desirable to recover these pyrites for three reasons: (1) Pyrites are potential sources of sulfur and iron. In 1967, for the fifth consecutive year, Free World consumption of sulfur exceeded production.3 Propelled by the shortage, the domestic price of sulfur has risen from $24 to $38 per long ton (bright). (2) The refuse, when placed in piles, becomes ignited. The pyrites (FeS2) bum, giving off SO,. Thus, the pyrites are a cause of air pollution. (3) Also, the pyrites undergo chemical reaction when exposed to air. The refuse is leached by waters which result in stream pollution due to the water-soluble iron and acidic reaction products. Coal refuse also contains coal minerals and clay minerals. Therefore, any process for recovering the pyrites must successfully separate them from the coal and clay minerals. In the study discussed here, ten different bituminous coal refuse samples were successfully upgraded in pyrite content. These samples represented a wide variety of coal waste materials from Pennsylvania and other states. The variabilities of the sulfur and coal contents are shown in Table I. The extremes are Sample J, a high sulfur-low coal, and Sample B, a low sulfur-high coal. Definitions of some of the symbols or terms used in this report are given below: Mesh size—Tyler standard mesh screen sieves with an opening based on the square root of two. Fe —Indicates iron, as determined by a stannous reduction-dichromatic oxidation method. S—Indicates sulfur, as determined by the ASTM "Eschka" method for sulfur in coal.

Jan 1, 1969

Jan 1, 1922

Jan 1, 1959

By Raymond Edmundson

BARITE probably was first mined in the United States in 1845, when a small deposit was operated in Prince William County, Virginia1. The next state to produce barite was Missouri, and according to Weigel2, mining began about 1860. Virginia was the leading producer during the early period of barite mining, but by 1893, Missouri was producing almost an equal amount3. From this date, Virginia, although not the leading producer, furnished large quantities of crude barite until oper-ations gradually declined about 1907. Since 1910, there has been only one producer in Virginia. It is not known when barite was discovered in each of the Virginia areas (Fig. 1), but it is reliably reported that mining on a commercial scale began in Campbell-Pittsylvania counties about 1874; Smyth County in 1877; and in the Russell-Tazewell area about 1890. Barite is widely distributed in Virginia, occurring in nineteen counties. The localities that contain material of some economic value have been grouped into six areas (Fig. 1), each designated by the county or counties in which the barite is found. As many of the smaller areas show a similarity in geologic occurrence, they will be considered in this paper as two major groups; namely, Appalachian Valley and Piedmont Province. The first group, which includes the barite deposits of Russell, Tazewell, Smyth, Botetourt and Roanoke counties, lies northwest of the Blue Ridge and its foothills and southeast of the Appalachian plateaus. The other group includes deposits from the Blue Ridge on the west to the western margin of the Coastal Plain, in Campbell, Pittsylvania, Bedford, Grayson, and Fauquier counties.

Jan 1, 1936

By W. J. Babyak

The habit planes for hydride precipitation in large grains of alpha zirconium and Zircaloy-4 were determined in specimens containing 161 and 136 ppm hydrogen, respectively. In zirconium, the hydride platelets precipitated on various pyramidal planes inclined to the basal plane at angles ranging from 10 to 50 deg and 75 to 90 deg. Hydrides were most frequent at inclinations of about 20 deg and 90 deg. In Zircaloy-4, hydride plates were inclined to the basal plane at angles vanging from 5 to 25 deg with the predominant inclinatioiz equal to 12 deg; no platelets were found near the prism plane position. In both zircoinium and Zir-caloy-4, hydrides were principally, but not exclusively, parallel to (1011) type planes. When the Zircaloy-4 gmins were subjected to tension stresses of 12,100 psi and 19,400 psi during hydride precipitation, the hydride habit was unchanged except that precipitation favored those habit planes which were inore nearly perpendicular to the stress direction. The stress-orientatioiz effect increased with the magnitude of the stress. THE hydride habit plane in a zirconium has been determined by several investigators. Langeron and Lehr1 in 1956 found platelets parallel to (1010) slip planes. In 1962, Westlake and Fisher2 confirmed these findings and showed that hydride precipitation on twin planes, as reported by Kunz and Bibb,3 was probably due to incomplete removal of worked metal from specimen surfaces. Secondary habit planes, ( 1011) and (1015), were also found by Westlake and Fisher under particular charging conditions where a hydride layer may have existed at the hydrogenation temperature. Most recently, walters4 and westlake5 again observed the (1010) habit exclusively in zirconium. Louthan and hgermans have reported that hydrides precipitate on various ( 101l ) and (112l) planes positioned 31.5 to 90 deg to the basal plane in Zircaloy-2. The present investigation was concerned with the hydride habit in Zircaloy-4 in relation to that in zirconium and the possible change in habit when precipitation occurs under stress. The latter consideration was prompted by the stress-orientation phenomenon originally reported by Marshall and Louthan.7, 8 I) EXPERIMENTAL Materials and Specimens. Chemical analyses of all materials are given in Table I. The zirconium specimen was a 1 by 4 in. section cut from wrought crystal bar that was hot-rolled at 790°C to 0.300 in. and cold-rolled to a final thickness of 0.095 in. All surfaces were mechanically polished and then chemically polished with a solution of H2O, HNO3, and HF (10:10:l by volume) prior to annealing. Grains as long as 0.25 in. were grown by thermally cycling the specimen three times (in 10-5 mm Hg vacuum) between 825" and 1000°C at approximately 125°C per hr. The specimen was isothermally annealed at 825°C for 24, 40, and 120 hr after each cy-

Jan 1, 1968

Jan 1, 1920

By M. L. Fuller

OWING to the nature of the die-casting process, freshly cast alloys are undoubtedly not at equilibrium from the standpoint of alloy phase relationships. After casting, therefore, they tend to undergo phase changes, with the ultimate effect of reaching a state of equilibrium at the aging temperature, beyond which no further change takes place. This phase alteration undoubtedly is one of the primary causes of the changes in dimensions and physical properties that zinc-alloy die castings undergo during aging. It is planned to report on this problem in a series of papers of which this is the first. The writers have made a study of commercial zinc die-casting alloys over a period of several years, utilizing the X-ray diffraction technic of determining the phase composition changes in the alloys. Up to the present, two principal phase changes have been observed which are capable of causing dimensional changes: (1) the segregation of secondary constituents from the zinc-base solid solution and (2) the beta aluminum-zinc decomposition. The latter is the subject of the present paper and studies on the former will be reported upon at a future time.

Jan 1, 1934

By R. W. Fountain, J. Chipman

THE solubility of nitrogen in iron and steel has been of considerable interest due to the role of nitrogen in strain-aging and in quench-aging. It is generally considered that quench-aging is the result of precipitation of carbide and nitride particles from supersaturated solid solution, while strain-aging results from the segregation of carbon and nitrogen atoms to dislocations.1-9 The rate of strain-aging is controlled primarily by the amount of carbon and nitrogen in solution and the temperature. In experiments on strain-aging of pure iron with only carbon or nitrogen as impurities, Fast" has shown that even after 40 hr at 50°C carbon did not give any strain-aging while

Jan 1, 1959

By M. N. Shetty

LARGE copper whiskers were grown from cuprous iodide by reduction with hydrogen at about 500°C. Carefully selected single-crystal whiskers of [loo], [110], and [Ill] orientations were used and the whisker shapes and cross sections are shown in Fig. 1. Spec-trographic analysis of a typical batch of whiskers showed that the composition was better than 99.9 pct with iron and silicon as the major impurities. The test specimens varied from about 70 to 400 u in diam and they did not show a conspicuous yield drop as observed in very fine whiskers (diam <25 u), tested by Brenner.1 The characteristics of the stress-strain curves were similar to those of bulk single crystals, even though the maximum flow stresses reached in some orientations were comparable to the yield stresses observed in fine whiskers. Mechanical properties of whiskers of different materials and copper whiskers up to about 100 u in diam have been reviewed,&apos; and a mechanism of slip band propagation in fine whiskers has been recently suggested.3 Whiskers in this work were tested in a floor-model Instron testing machine using low strain rates. (Details of the testing procedure, diameter dependence of the yield stress, and the characteristics of the load elongation and stress-strain curves have appeared esewhere.4) Due to the extensive deformation, >50

Jan 1, 1970

By Paul A. Farrar, Louis P. Stone, Harold Margolin

The Ti-Mo-0 system was investigated in the region 0 to 45 wt pet Mo and 0 to 10 wt pet 0, from 600° to 1400°C. Solidus data are also presented. Isothermal sections at 700°, 900°, 1100°, and 1300°C, and vertical sections at 1 and 28 wt pet Mo, and 1 and 10 wt pet 0 are included. STUDY of the Ti-Mo-0 system has been carried out as part of a general study of titanium phase diagrams. The binary Ti-Mo system has been investigated in whole or in part by several investigators.1-8 It was found that molybdenum and ß-tita-nium form a complete series of solid solutions and that the ß/a + ß transus is depressed to below 600°C at approximately 30 pet Mo.* The Ti-O system has been investigated partially or fully in the range 0 to 30 pet 0 by several investigators." Extensive solubility of oxygen occurs in the field. While a is

Jan 1, 1957

By H. A. Dierks

PENNSYLVANIA&apos;s anthracite region lies in the heart of the richest and most densely populated area of the U. S. Nearly 70 million people live within a radius of 500 miles, in which 130,000 manufacturing plants employ more than 8 million workers. The region comprises some 3000 sq miles and contains 484 sq miles of coal measures, which folding and erosion have divided into four separate and distinct fields, known as the Northern, Eastern Middle, Western Middle, and Southern.

Jan 10, 1957

By R. H. Cox, A. S. Allen, James Paone

The southwestern Illinois communities of Belleville and Maryville lie within the greater metropolitan area surrounding St. Louis, Missouri. They also lie within that part of the Illinois coal basin where the Number 6 coalbed has been mined for more than a century. About half the coal was left as pillars to support the ground surface. Years later, however, damaging movements are affecting buildings, streets, and public utilities in some areas. They are generally believed to be related to abandoned mine workings. The threat of continued or increasing incidence of damage raises the need to explore other subsidence-control measures for protecting affected areas with high population density.

Jan 2, 1978

A LARGE proportion of the steel that is melted and refined in the United States and poured into ingots is made in basic open- hearth furnaces. The capacity of these furnaces varies over a wide range with a large majority falling within limits of 50 to 200 tons (Fig. 1) The two general types of furnace design used are stationary [ ] and tilting furnaces, the former being much more common. The fuel burned in such furnaces is either one of several types of gas, or a liquid fuel such as oil or tar, or a combination of gas and liquid fuel. GENERAL FEATURES OF FURNACE CONSTRUCTION The design of a modern stationary furnace built to burn liquid fuel and with a capacity of 175 tons is shown in Figs. 2 to 4. The cross- section of the furnace at the tap hole is illustrated in Fig. 2, which shows the bottom construction, sloping back wall, and the rigid steel

Jan 1, 1944

By Robert Glass Cleland

THE OUTBREAK of World War II found Phelps Dodge, thanks to both foresight and good fortune, in a position to increase production of its mines and factories to meet the insatiable military and domestic needs of the times, far beyond all previous records. With the timely completion of the expansion program at Morenci, the company&apos;s copper output rose to approximately 447 million pounds in 1942 and to over 478 mil- lion pounds the next year, compared to some 300 million pounds in 1939. To meet the civil and military needs for fabricated cop- per products, the Phelps Dodge Copper Products Corporation carried out an expansion program comparable in size to that of the Phelps Dodge mining operations. It built new plants, enlarged and reorganized those already in operation, multiplied the number of technical experts on its staff, adopted new methods and new machines for the new prod-

Jan 1, 1952

By Charles Pack

Die castings may be defined as metal castings made by forcing molten metal, under pressure, into a metallic mold or die. It is necessary to keep this definition in mind to avoid confusing this process with other permanent-mold casting processes. The fundamental principles of the process have been known and practised many years. The simplest application is embodied in the modern linotype machine in which molten metal (usually tin-lead alloy) is forced under pressure into a metallic mold. The pressure is derived from a piston and cylinder immersed in the molten metal. Progress in the art of die casting may conveniently be divided into three groups: Machine for imparting pressure to the metal, material for the die or mold, casting alloys. The problem of delivering molten metal under pressure into a die is comparatively simple, when dealing with low-fusing-point alloys, as the alloys of lead and tin, but it is much more complicated when dealing with metals of higher fusing points, such as the alloys of zinc, aluminum, and copper. Although the art of die casting is comparatively new and, to a large extent, unknown, the records of the patent office are replete with patents on the subject. Fig. 1 shows the Underwood machine patented in 1902; this is probably one of the first machines designed for the production of commercial die castings. The relation of this machine to the linotype casting machine is clearly apparent. A cylinder and piston are immersed in the molten metal, the application of power to this piston forcing the molten metal, under pressure, into the mold or die. The Doehler machine, Fig. 2, patented in 1907, is based on the same general principles. This machine is used to a large extent at the present time, throughout the United States, for the production of zinc, tin, and lead alloy die castings. In the machine shown in Fig. 3, patented by Doehler in 1910, compressed air is used for forcing the metal into the die. In Fig. 4 is shown another of this type of machine. Here compressed air is applied to the surface of the molten metal to force it into the die. In a machine patented by Chandler in 1914, shown in Fig. 5, the

Jan 1, 1919