Search Documents

By Shosei Serata

Conventional roof bolting may be giving ground to a new technique that utilizes only the ground itself to stabilize mine openings. This newly developed stress control technique (SCT) has initially been used in sedimentary ore bodies that are both overlain and underlain by weak strata. The technique is also suited to the design of production panels and main entry systems, and is readily adaptable to room and pillar as well as total- extraction mining, including both shortwall and longwall coal mining. In applications where the technique has been used, the requirements for roof bolting and floor renewal were virtually eliminated. The SCT comprises three basic methods and covers a wide range of problems associated with failing roofs and heaving floors in underground mines (see Table 1).

Jan 5, 1976

By Mack H. Shumate

1 Raw coal from Truax-Traer Coal Co.'s Burning Star Slope mine, Jackson County, Ill., is brought to the surface by the new 42-in. slope belt haulage conveyor at the rate of 850 tph. The loading system shown above employs four storage tracks, two tail tracks for loading, and four 25-hp hoists, operating in pairs, and coupled to two dolly cars to move the trains of cars through the tipple. The system has a capacity for loading 1800 tph. One operator is needed to load on each of two shifts. A third man working for a few hours on night shift sets up for the morning cycle. Railroad crews bring in empties placing them in the storage yard, twenty cars to the track. Trains of empties are pulled through to the tail track and loaded on the return; hoists at opposite ends pull the trains in each direction. [ ] 2 Pairs of hoist drums are interconnected electric- ally by a Trench lay cable buried between the tracks. When one hoist operates moving the cars, the tail hoist idles with brake released. The operator, situated in the tipple over the cars, views the storage yard at the end of the first shift (left). When returning loaded cars to yard, four or five cars are held on the dolly to couple the next string of empties. Empties are ready for loading on the tail track (right). Differing from a gravity system in which empty and load tracks are on a slight grade, this system is designed for 80 railroad cars for a two-shift operation and one rail service per day.

Jan 6, 1962

By T. A. Griffin

Surface mining today is faced with a twin challenge: (1) accelerating the rate of removal of massive quantities of overburden and ore, and (2) replacing comparable high volumes of overburden in the mined-out portion of the pit. It is against this background, coupled with increased demands for fossil fuels worldwide and legitimate environmental concerns, that the role of bucketwheel excavators and reclaimers has been raised to new prominence.

Jan 10, 1974

The earliest reference to coal in Tennessee is that by Dr. Walker in 1750 (see p. 18) where he saw it near the present site of Middlesboro. The next reference found is in 1798 when Morse stated, "some of these mountains, particularly in the, Cumberland, or Great-Laurel Ridge, are the most stupendous piles in the United States. They abound in ginseng and coal."' There must have been many places where it was seen in that interval, but nearly as long a time elapsed before Morris, in 1834, said that "fine beds of stone-coal exist in both East and Middle Tennessee."2 In a description of the Dover Iron Works, on the left side of the Cumberland River, a few miles above Dover, in Stewart County, it was said that "80 hands were employed in digging and transporting stone coal" and that the "plant had been running at least since Oct. 2, 1834."3 While doubtless coal had been used locally, this is probably the first use of it commercially in the state. The consumption of stone coal was 4,000 tons per year. In this same geological report openings of coal are mentioned near Battle Creek, Marion County, and in Bledsoe and Rhea Counties, where it was being used locally by blacksmiths; some other places were being worked near the turnpike road from Kingston to the Crab-Orchard, the product being hauled three miles to the Tennessee River and loaded in barges; farther west in. White County several outcrops were found. In Fentress County, several pits had been opened, the coal being sent down the Obey and Cumberland Rivers, and openings were also seen in Morgan, Anderson, Roane, Warren, Hamilton and Franklin Counties. The writer had hoped to publish an account of the iron works in the state but was unable to obtain the necessary information. He was told by an old iron-master, Mr. E. Embree, that

Jan 1, 1942

By J. J. Gilman

The data presented indicate that the critical shear stress and strain-hardening Thedatapresentedrate of a zinc monocrystal depend on the orientation of its slip direction with respect to its external boundaries. The tendency of a crystal to form deformation bands also depends on its shape. THE plastic behavior of pairs of zinc monocrystals in which both members of the respective pairs had the same orientation with respect to the longitudinal axis, but each had different orientations with respect to their rectangular external shapes, were compared in this investigation. The purpose of the investigation was to see what influence the shape or surface of a zinc crystal has on its mechanical properties. In a previous investigation of triangular zinc monocrystals,1 anomalous axial twisting was observed which seemed to be related to the triangular shape of the crystals. Wolff,' in 400°C tensile tests of rectangular rock-salt crystals bounded by cubic cleavage planes, found that, of the four equivalent slip systems, the two with the "shorter" slip directions yielded and produced slip lines at lower stresses than the other two. This observation and the work of Dommerich³ as formulated by Smekal4 as a "new slip condition" for rock-salt: "among two or more slip systems permitted by the shear stress law, with reference to the formation of visible slip lines by large individual glides, that slip system is preferred which has the shortest effective slip direction." More recently, Wu and Smoluchowski5 reported essentially the same effect for ribbon-like (20x2x0.2 mm) aluminum crystals at room temperature. Experimental Chemically pure zinc (99.999 pct Zn), purchased from the New Jersey Zinc Co., was the raw material. Glass envelopes, containing graphite molds and zinc, were evacuated while hot enough to outgas the graphite but not melt the zinc. At a vacuum of about 0.2 micron the envelopes were sealed off and then lowered through a furnace at 1 in. per hr so as to melt and resolidify the zinc and produce mono-crystals. One-half of one of the molds is shown in Fig. la. Each mold consisted of four pieces from a cylindrical graphite rod that was split longitudinally and transversely at its midpoints. Rectangular milled grooves 0.050 in. deep and % in. wide formed the mold cavity when the split halves were assembled with twisted wires. Fig. lb shows the specimen shape obtained when the top and bottom mold-halves were rotated 90" with respect to each other. Good fits prevented leakage and excess zinc was necessary to provide enough liquid head to fill the mold completely. In removing soft crystals from the molds it was impossible to avoid small amounts of bending. However, manipulations were carried out whenever possible with the crystals protected by grooved brass blocks. All specimens were annealed prior to testing. From the top and bottom sections of each crystal, X-ray specimens and tensile specimens 7 to 8 cm long were sawed. The tensile specimens were annealed inside evacuated tubes for 1 hr at 375°C. Next the crystals were cleaned and polished by 2-min dips in a solution of 22 pct chromic acid, 74 pct water, 2.5 pct sulphuric acid, and 1.5 pct glacial acetic acid.' Cleaning was followed by a 10-sec dip in a 10 pct caustic solution, then washed in water and alcohol, and dried. This treatment results in a bright surface covered by an invisible oxide film. The testing grips were a slotted type with set screws and were supported in a V-block during the mounting operations in order to avoid bending the crystals. A schematic diagram of the recording tensile-testing machine is shown in Fig. 2. The machine has been described elsewhere.' The head speed was 0.3 mm per sec for all tests. The crystal orientations were determined by the Greninger X-ray back-reflection method with an estimated accuracy of 1. Description of Crystal Geometry A schematic picture of a rectangular zinc mono-crystal is shown in Fig. 3. ABD designates the front edge of a basal plane (0001) of the crystal, the only active slip plane for zinc at room temperature. Of the three possible (2110) slip directions, the active one is indicated by an arrow. Cartesian coordinates are taken parallel to the specimen edges. The normal, n, to the basal plane (n is parallel to the hexagonal axis) has the direction cosines a, ß and ?. X0 = 90 — y is the angle between the longitudinal axis and

Jan 1, 1954

By George T. Bator

If confronted with the problem of pumping a mixture of slime-free sand, gravel and boulders up to six in. in diameter, at the rate of 175 tons per hr in one single-stage pump against a static head of 90 ft and a total head of 140 ft, of which 20 is on the suction side, an engineer might be forgiven for backing away from the job, especially if he were also told that the pump wearing parts must have a minimum hardness of 550 Brine11 for the sake of abrasion resistance. Yet precisely that feat has been accomplished in the gravel pit of John B. LaGarde, Inc., near Anniston, Ala. The pump used is of decidedly novel design and its successful operation since installation 1.5 years ago suggests that it may be of timely interest in numerous other applications in the mining industry, such as pump transportation of coal washer refuse or rock from open-pit's without unduly fine crushing.

Jan 9, 1950

By W. H. McFarland

The mechanical properties have been determined for a large number of alloy-free martensitic steels with carbon contents ranging from 0.08 to 0.20 pct and with manganese contents of about 0.4 to 0.5 pet. These steels were tested 1) as water-quenched, 2) after quenching, temper rolling, and tinning, and 3) after tempering treatments which involved temperatures from 400o to 1300oF and times from 1 min to 8 hr. The majority of these tests represent steel from commercial-size coils, i.e., strip 32 in. wide, coil weights up to 20,000 16, and steel thicknesses from 0.0055 to 0.024 in. As a result of these treatments, it has been shown that as-quenched low-carbon alloy-free steels can be produced with tensile strengths ranging from 140,000 to 220,000 psi and tensile elongations from 3.0 to 4.0 pet in 2 in. The tensile strength of the as-quenched martensites can be represented by the equation, tensile strength (ksi) = 119 + 560 (wt pet C). The response to tempering of these steels is related to previous work by Muir, Averbach, and Cohen and by Grange and Baughman. Strain aging of low-carbon martensite has also been investigated. If low-carbon steels are defined as those steels with a maximum carbon content of 0.2 pet, it is found that the literature on low-carbon, alloy-free martensites contains little data on the mechanical properties of these steels. However, the following facts concerning low-carbon alloy-free martensites seem firmly established:'-' 1) The major factors in controlling the strength of the martensite appear to be a) fine structure, b) the internal strain resulting from the transformation, and, particularly, c) the amount of carbon in solid solution. 2) In low-carbon steels, the martensite is auto-tempered and is in the form of needles with only minor amounts of internal twinning, whereas the martensite in high-carbon steels forms as plates which are internally twinned on a fine scale. 3) Care must be taken in comparing the results of work that has been done on low-carbon steels with varying amounts of alloying elements to data on plain carbon steels. As has been noted by Irvine, Pickering, and Garstone,6 alloying elements generally lower the martensite start temperature and, thereby, decrease the amount of auto tempering obtained during the quench. This makes it difficult to

Jan 1, 1965

Society of Chemical Industry (London), American Section. Foster D. Shell, Secretary, 130 Clinton St., Brooklyn, N. Y. Publications of this Society are not of direct interest in this directory but the address of the Society is listed that the reader may have it on record for reference. Subscription to the Journal (A the Society costs £ 2 10s, or $12.50 at the normal rate of exchange. Individual copies are is 9d, postage extra.

Jan 1, 1933

By J. Dehais, W. A. Wallace

The pressures of urbanization are forcing producers of construction minerals either to transport their product greater distances or find new mineral sources. In areas with significant urban development near the coastal zone, offshore resources may prove to be an economically attractive alternative source. This paper addresses the economic viability of offshore mining of fine mineral aggregate. It proposes a model using a mathematical programming formulation based upon past research on both the onshore construction aggregate industry and the coal industry. The model is then used to assess offshore mining economics in the greater New York metropolitan area. Results show that in this region total consumer cost would be reduced by offshore mining of fine aggregate. In addition, increasing economies of scale could be realized by progressively larger mining operations. The distribution of these savings is also discussed.

Jan 1, 1982

By Gerard A. Flierman

INTRODUCTION There is a lot of discussion about the relative merits of sinter and pellets as components of a BF-burden. Many people claim that sinter is to be preferred and that the percentage of pellets in the burden must be restricted to 20%. During BF-trials in IJmuiden various amounts of pellets having various basicities were tried. It was concluded that there were no significant differences in furnace performance. Consequently the choice between sinter and pellets must be based on the local manufacturing costs (1). Table 1 gives a summary of the pellet experience in IJmuiden. [ ] Because the BF-trials were relatively short, a survey of published BF-operating data has been undertaken to investigate if differences between a sinter and pellet based BF- practice could be found. The comparison of BF-operating results has been restricted to coke rate and productivity.

Jan 1, 1977

The Empire IV expansion is on schedule for completion in January 1980; Hibbing Taconite's 2.7 million ltpy* expansion should be finished late in 1979; and Reserve Mining's tailing disposal project is on target for April 1980. Erie Mining Co., the first to bring 170-ton haulage trucks to the Mesabi Range, reports excellent operating results, and Inland Steel expects to produce 80% of its pellets in 1979 using coal rather than oil. One Michigan mine has so many inspectors that it has hired a school bus to transport them around the operation; and a contractor reports that mine construction projects of the future may require the training of 15,000 workers. All of this was covered at the 52nd Annual Minnesota Section AIME Meeting and the 40th University of Minnesota Mining Symposium, a joint event held each January in Duluth.

Jan 3, 1979

By Edwin S. Johanson, Ronald H. Wolk, Clarence A. Johnson, Harold H. Stotler, Katherine C. Hellwig

The H-Coal process, an ebullated bed reactor system for converting coal to liquid fuel, is described. Results from long-duration continuous flow bench-scale operations with Wyoming Wyodak, Arizona Black Mesa, and Utah Kaiparowits Plateau coals are presented. Economic data on the conversion of these coals to liquid products are given. The potentials of the H-Coal process in regard to coal from western producers is stressed.

Jan 1, 1974

NOT all the lead in the country comes from the big operations. A member sends in this photograph of the wash-up from the "Old Timers Lead Mine," at Galena, Ill. He omitted to inclose a flow-sheet of the concentration process, which detracts somewhat from its value to the technical man, and cost figures are lacking. Perhaps he was run off the lease when his questions on milling recoveries became too searching. Still and all, according to the picture the plant ap-pears to be operating efficiently. It is reasonable to believe that the cost of electric power per ton milled is held to a low figure. We commend the proper pro-fessional stance of the gentleman on the business end of the hand jig, though we look in vain for the time honored spring board to aid him in giving the most efficient stroke.

Jan 12, 1927

By S. H. Ash

Safety records in the mineral industry for 1954 will do well to hold their own as compared with 1953, because of the poorer rate in the coalmining branches, even without the recent mine explosion at the No. 9 mine of the Jamison Coal & Coke Co., Farmington, W. Va., that killed 16 persons. .The cause of that disaster has not yet been ascertained. The metal-mining branch appears to have improved its record over the last year, however. Health Diesel equipment continues to be favored in non-coal mines. Equipment includes locomotives, trucks, tractors, and muckers. Of major concern and interest is the establishment of a new threshold limit for oxides of nitrogen-5 ppm as compared with 25 ppm. This gas is the most harmful component of diesel-engine exhaust gas

Jan 3, 1955

By Henry Otto

THE anthracite industry can be divided into two parts-the underground, or mining, and the outside, or preparation or manufacture. To understand recoveries in the two branches, some of the history of the industry and the changes that have taken place in the past century should be considered. It is a long step from 1807, when 55 tons were produced in the Wyoming field, to 1917, the peak year, when 80,841,223 tons were shipped to market from all the fields. In 1820, the Lehigh Coal Co., the predecessor of the Lehigh Coal & Navigation Co., shipped 365 tons in arks down the canal of the Lehigh Navigation Co. The Schuylkill field was not opened until 1822, when 1480 tons were shipped. The Wyoming field really became a producer in 1829, when 7000 tons were mined and shipped. It is well to note, at this time, the passing of the Coleraine colliery after a life of 88 years; in collieries of this age will be found the. romance of the region, as well as the history of the changes to date.

Jan 1, 1925

By Oliver Bowles

When a new type of equipment revolutionizes methods of quarrying one kind of stone, producers of other kinds focus their attention on its potentialities in their particular fields. The purpose of this paper is to discuss the accomplishments of the wire saw in slate, to show its more limited attainments in other kinds of stone, and to point out the possibilities of much wider application. A wire saw consists of a 3/16-in. or ji-in. three-strand wire cable that runs as a belt and cuts the rock by abrasion. (Fig. 1. The teeth of the saw are sand grains carried in the grooves between the strands. Accomplishments in Slate† Initial experiments with wire saws by the U. S. Bureau of Mines in the Colonial Slate Quarry, Wind Gap, Pa., in 1926, attained success so immediate and pronounced that within two years in virtually every quarry in the neighborhood of Wind Gap, Pen Argyl and Bangor, the most productive slate area in the United States, wire saws were substituted for channeling machines. An 80-ft. cut in slate is shown in Fig. 2. The technique of operation has been described in several reports (references at the end of the paper). The present purpose is to summarize the accomplishments in a large, typical slate quarry after nine. years of experience. Parsons Bros. Slate Co., at Pen Argyl, Pa., substituted two wire saws for six channeling machines in 1927. The following comparisons are made between the present method with wire saws and the former channel-ing-machine method. Rate of Sawing.—The average rate of cutting with a wire saw in the early days of its operation, as determined by the Bureau of Mines', wits 14 to 17 sq. ft. per hour. Parsons Bros. Slate Co. estimates the present rate of cutting at about 25 sq. ft. an hour, whereas the channeling-rnarhirle

Jan 1, 1938

By Oliver Bowles

When a new type of equipment revolutionizes methods of quarrying one kind of stone, producers of other kinds focus their attention on its potentialities in their particular fields. The purpose of this paper is to discuss the accomplishments of the wire saw in slate, to show its more limited attainments in other kinds of stone, and to point out the possibilities of much wider application. A wire saw consists of a 3/16-in. or ji-in. three-strand wire cable that runs as a belt and cuts the rock by abrasion. (Fig. 1. The teeth of the saw are sand grains carried in the grooves between the strands. Accomplishments in Slate† Initial experiments with wire saws by the U. S. Bureau of Mines in the Colonial Slate Quarry, Wind Gap, Pa., in 1926, attained success so immediate and pronounced that within two years in virtually every quarry in the neighborhood of Wind Gap, Pen Argyl and Bangor, the most productive slate area in the United States, wire saws were substituted for channeling machines. An 80-ft. cut in slate is shown in Fig. 2. The technique of operation has been described in several reports (references at the end of the paper). The present purpose is to summarize the accomplishments in a large, typical slate quarry after nine. years of experience. Parsons Bros. Slate Co., at Pen Argyl, Pa., substituted two wire saws for six channeling machines in 1927. The following comparisons are made between the present method with wire saws and the former channel-ing-machine method. Rate of Sawing.—The average rate of cutting with a wire saw in the early days of its operation, as determined by the Bureau of Mines', wits 14 to 17 sq. ft. per hour. Parsons Bros. Slate Co. estimates the present rate of cutting at about 25 sq. ft. an hour, whereas the channeling-rnarhirle

Jan 1, 1938

By J. T. Crawford

THE purpose of this paper is to present some data and comparisons regarding three types of Rheolaveur plants washing bituminous coal from the Pittsburgh seam. It deals only with the sections that handle coarse coal. The Rheolaveur system consists of launders or troughs in which coal and its associated impurities are conveyed by water. The impurities, being heavier than the coal, settle toward the bottoms of the launders and are drawn off through specially designed openings called Rheo boxes. Fundamentally, each plant consists of straight-sided, flat-bottomed launders of varying width and length, each launder equipped with one or more Rheo boxes for the removal of high-gravity fractions of the feed that are undesirable in the cleaned coal. Each launder has at least two longitudinal sections, the first with a slope of from 1 1/2 to 4 in. per foot of length, called the classification section. The single-box launder has a classification section followed by a washing section ahead of the box. A two-box launder is a single-box launder followed by a washing section and a second box. The slope of the washing section between the first and second boxes is determined to some extent by tonnage. At the end of the classification section, which may vary from 8 to 15 ft. in length, the slope abruptly flattens out to a slope of from ½ to 1 in. per foot of length. This flatter section of the launder, called the washing section, may vary from a few feet, in a single-box launder, to 15 ft., in a two-box launder.

Jan 1, 1938

By A. H. Daane, B. J. Beaudry

The yttl-irtm-nickel system has been investigated by metallo-graphic, thermal ard X-ray methods. There are nine intermetal-lic compounds present: Y3Ni, Y3Ni,, YNi,, YNi,, Y,Ni,, YNi,, and Y,Nil, which rodergo peritectic decomposition and YNi and YNi, which melt congruently. There are eutectics at 34.8, 57.5 and 93.3 at pct Ni which melt at 805°, 950 and 1285 C, respectively. Crystallographic data are given for YNi, YNi,, YNi,, YNi5and Y,Ni,. The terminal solid solubility is low. In recent work by Fisher and Fullhart' in which yttrium crucibles to be used for containers of uranium-chromium eutectic were clad with a high nickel steel, a low melting phase formed where the yttrium was in contact with the steel. To investigate the cause of this phenomenon, Daane, et al. made a survey study of yttrium systems with chromium, manganese, iron, and nickel and found an 18 wt pct Ni (weight percent) alloy to melt at approximately 950°C. voge13 in a study of the systems of cerium, lanthanum, and praseodymium with nickel found six compounds of the same formula in each system, i.e., R3Ni, RNi, RNiz, RNi3, RNi4, and RNi5. Since there is a great similarity between yttrium and the rare earths, compound formation was likely to occur also in the yttrium-nickel system. voge13 observed that the ability of transition metals to form compounds with the rare earths diminishes in the order nickel, cobalt, and iron while no compounds are formed with manganese, chromium, and titanium. Available data on yttrium systems with these elements indicate similar behavior, except that a slightly greater tendency toward compound formation is apparent. Simple eutectics with limited solid solubility have been found in the yttrium-titanium4 and yttrium-chromium5 systems, but at least one compound is present in the yttrium-manganese system.' In the case of yttrium-iron, at least three compounds are present,5 while only two are present in the cerium-iron,' and no compounds are present in the lanthanum-iron5 system. On the basis of both the trend in the alloying behavior of yttrium and rare-earth metals with the first transition series metals and the large number of compounds in the cerium-nickel system, one might expect six or more compounds to form in the nickel-yttrium system. A consideration of Hume-Rothery's rules of alloying based on size factor, electronegati-vity, and valence predicted low terminal solid solubility and possible compound formation. The present study was undertaken to confirm these predictions of

Jan 1, 1961

By C. R. Fettke, Bela Hubbard

During the summer of 1916, while on a visit to the United States Agricultural Experiment Station at Mayaguez, Porto Rico, the writers were told by D. W. May, the director, that an occurrence of manganese ore had been reported from the mesa southeast of Mayaguez. A visit to the locality showed that the mesa is covered by a mantle of bright red soil resting upon serpentine. Here and there over its surface concretionary masses of limonite have been mashed out of this soil. These were apparently mistaken for manganese ore. On account of the similarity of this occurrence to the extensive iron deposits of northeastern Cuba, it was thought that a brief description based upon a two days'reconnaissance survey of the area mould be of scientific interest. Mayaguez is on the west coast of Porto Rico, at Mayaguez Bay, which is the third in importance of the harbors of the island. The city itself is about 3/4 mile inland on the low-lying plain at the mouth of the

Jan 1, 1920