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A brief review is given of the history of the Colliery to date together with the reasons for the development of an additional seam.Investigations into the quality of the coal ami its suitability for the production of metallurgical coke and determination of the economic mining limits and coal reserves are discussed. The commencement of mining operations and the inter-seamarrangements necessary for the disposal of coal won are described with the stages in the opening out of the seam itself and the reasons for the installation of a 48-in. trunk conveyor belt. Choke and manning of face equipment are considered and also the work of secondary development and pillar extraction.It is concluded that with modern face equipment and conveyor belt lines, concentrated mining followed by immediate extraction of pillars is practicable and is giving excellent results at Burwood Colliery.INTRODUCTIONBurwood Colliery, the total holding of which now comprises some 3,140 acres of land and 1,450 acres of sea leases, has mined the Borehole Seam since 1883. The early work took place from Nos. 1 and 2 shafts at Glenrock Lagoon and later on at Nos. 3 and 4 shafts at Whitebridge to which the centre of operations shifted in 1893, shaft sinking at this latter area having commenced in 1888.As all the early operations were confined to the Borehole Seam, reserves of coal on this horizon had been considerably reduced by the mid 1930's, so a cross measure drift was driven to the Victoria Tunnel Seam which is about 300 ft. above the Borehole Seam, and fully mechanized coal winning commenced from the second seam in 1938. Subsequently this cross measure drift was extended to the Borehole Seam and complete mechanization of the south-west sections of this seam achieved by 1945.Four track mounted mechanical units were put into operation in the latter area and these worked in a southerly and...

Jan 1, 1958

By Fred C. Wrobbel

Two counties in Illinois, Ope and Hardin, and three counties in Kentucky, Crittenden, Livingston and Caldwell comprise the entire Kentucky-Illinois fluorspar district. The output from these five counties, however, makes up over 60 percent of our domestic fluorspar production, amounting to some 175,000 tons of finished product in 1956, The area is rough and hilly. It is bisected by the Ohio River, and has numerous smaller rivers and creeks. Add to this a generous average annual rainfall, in excess of forty inches, and it is understandable that the-area-can boast of an ample water supply. An abundance of water, however, is unfortunately not always conducive to ideal mining conditions. The faulted structure of the area and the soluble Mississippian limestones make the subsurface sediments' willing hosts to the surface water. Limestone cavers and sinkhole topography also compound the occurrence of underground water. It is little wonder, then, that water frequently presents an economic problem in the area, particularly in vein-type mining.

Jan 1, 1958

By E. E. Creitz

Application of the usual chemical methods to the determination of beryllium in the mineral-dressing products of a spodumene pegmatite was found to be unsatisfactory as to speed, accuracy, sensitivity, and range of analysis. A spectrographic method is described for the determination of beryllium. Samples are ground, mixed with borax, high-purity, flake graphite, and an internal standard; then they are fused, reground, pelletized, and excited with a high-voltage-spark discharge. Investigation of several spectrographic techniques to overcome matrix effects are described. The method developed gives results for beryllium in the concentration range from 0.002 to 5.0 percent; the average probable error of duplicate determinations was below 3.0 percent of the quantity present. INTRODUCTION The main source of beryllium in pegmatite is the mineral, beryl. Many of the conventional methods for the determination of beryllium in beryl are not suitable for control purposes because of lack of speed and accuracy, especially in the range below a few tenths percent. Beryl resists the usual chemical attack and can be lost in a hurried chemical analysis.

Jan 1, 1958

By H. A. Steane

THIS PAPER describes the re-grind section in the 2,000-ton per day, lead-zinc flotation mill of Canadian Exploration Limited, near Salmo, B.C. There are two re-grind units in operation, one in the lead circuit, and one in the zinc circuit. In each unit, the rougher concentrate is re-ground ahead of the cleaning circuit. These re-grind units have made valuable improvements in the concentrate grade, and with no loss in recovery by over-grinding galena or sphalerite. Since the initial installation of this re-grind section, the plant throughput has been increased gradually from 1,600 tons to 2,000 tons per twenty-four hours, and, as shown by the screen analysis of mill tailing, a coarser overall grind has been accepted, from 55 per cent to 45 per ?cent minus 200 mesh. There has been no increase in grinding capacity, but two mills have been taken from the main grinding circuit and used for the re-grind circuit.

Jan 1, 1958

By A. W. Cochardt

MOST of the current high temperature materials are precipitation-hardened alloys. These alloys are usually soft when quenched from a solution heat-treatment temperature, but become harder

Jan 1, 1958

By A. G. Oppegaard

Most iron ores treated by the R-N direct reduction process yield metallic iron products considerably lower in titanium, manganese, and chromium oxides and alkaline metal sulfates/sulfides than were contained in the original ores. These metallic iron products are suitable as feed stock for the open hearth and electric steel-making furnaces. The elements which are rejected in part are acceptable in the product since the product is designed to by-pass the blast furnace. R-N reduction conditions (PCO+H2-1 atmosphere, 1830° to 2150° F.) are adjusted for each ore. The iron ore which is reduced to 90 to 95 percent metallic iron is then subjected to the conventional beneficiation techniques. Under these conditions, 55 to 80 percent of titanium oxides, 75 to 95 percent of manganese oxides, 60 to 90 percent of chromium oxides and up to 97 percent of alkaline metal sulfates contained in the ore are rejected with the gangue to the non- magnetic tailings. The metallic iron products illustrated in this work contained 89 to 96 percent total iron, one to five percent TiO2, 0.2 to one percent MnO, 0.3 to 1.6 percent Cr2O3 and/or up to one percent alkaline metal sulfide. Usually only one of these components was present. Recoveries ranged from 80 to 96 percent of the iron in ore.

Jan 1, 1958

By H. R. Shell

To obtain a better understanding of the crystallization of fluoride containing amphiboles from melts, an investigation of the range of stability between fluoramphi-boles and other minerals was conducted by the Bureau of Mines. This study has shown that the stability of fluoramphiboles is strongly influenced by both fluoride concentration and isomorphic replacement. Over 150 reactions were made with different compositions and reaction conditions. substitutions attempted and the phases that formed when the composition was crystallized by cooling from the melt are discussed. The attainment of equilibrium in these multicomponent systems is not claimed. Many ions that would be expected to enter the amphibole structure instead resulted in crystallization of phases other than amphibole. Those compositions that resulted in a high yield of acicular fluoramphibole by crystallization from the melts are shown in table 2. The fluoramphiboles obtained from melts typically had an acicular crystal habit and a hardness of 6 to 7 on the Mohs' scale. Although many had relatively high length to cross section ratios, none were fibrous; it was concluded that the possibility of synthesizing a fibrous fluoramphibole from a melt was low. However, many compositions can be crystallized into a tough, hard, impact-resistant mass of interlocking acicular crystals.

Jan 1, 1958

By C. T. Baroch

CESIUM-137 ISOTOPE began to displace cobalt-60 III the treatment of cancer during 1956. Production and Consumption.-Consumption of cesium and rubidium was approximately the same as in 1955. Production, however, decreased, as several companies shipped from stocks produced in previous years. South Africa was the source of most cesium and rubidium minerals used in the United States in 1956. Cesium and rubidium metals and compounds were produced from ore by: DeRewal International Rare Metals Co., Philadelphia, Pa.; Fairmont Chemical Co., Inc., Newark, N. J.; Foote Mineral Co., Philadelphia, Pa.; and Rocky Mountain Research, Inc., Denver, Colo. Most sales were to domestic consumers, but small quantities were exported to Australia, England, Germany, and Sweden. New production facilities were under construction in. 1956 by San Antonio Chemicals to produce mixed potassium, rubidium, and cesium carbonates. A plant capable of separating and packaging 200,000 curies of cesium-137 annually was under construction at Oak Ridge National Laboratory.6

Jan 1, 1958

By G. W. Birge

This report describes the carbonizing properties of the principal coal beds of McDowell County, W. Va. Coals from 14 coal beds were selected for study: Upper Cedar Grove, Middle Cedar Grove, Lower Cedar Grove, Eagle, Douglas, Iaeger, Sewell, Welch, Beckley, Fire Creek and Pocahontas Nos. 3, 4, 5, and 9. Selection was based upon estimated minable reserves. McDowell County coals rank either as high-volatile A, medium-volatile, or low-volatile bituminous coal, and this variation in rank is reflected in the wide diversity of the carbonization properties of the coals. All coals tested were either satisfactory as mined or could be upgraded to meet present chemical standards for metallurgical coke; the coals produced strong coke, as determined by ASTM shatter and tumbler tests.

Jan 1, 1958

By Robert Alfred

This paper is one of a aeries being published by the Federal Bureau of Mines on methods and practices used in mining and preparing crushed stone for market. Performance, in terms of units of work or tons produced per machine and per operator man-hour, is given whenever that information can be obtained. Direct operating costs are useful for comparing different methods and are included if available. In addition to descriptions of equipment and methods used the Bureau considered it desirable to discuss the engineering reasons for the choices that have been made, This paper is particularly concerned with the operation of the Liberty quarry and plant of the Campbell Limestone Co, The plant is in Pickens County, adjacent to the main line of the Southern Railway, and is about 18 miles west of Greenville, S, C. Access also is available by United States Highway No, 123, The company's main offices are at Knoxville, Tenn.

Jan 1, 1958

By d&apos, Kathleen J. Amico

THIS SUMMARY is identical to the summary given in volume III of this series of mineral production in the United States (including Alaska and Hawaii), its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico and of the principal minerals imported into and exported from the United States. For further details on production see commodity and area chapters. A summary table comparing world and United States mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers [ ]

Jan 1, 1958

By J. R. Tonry

In the grinding of dry non-metallic materials such as rocks, ores, gypsum, lime, and cement clinker, it is recognized that only a relatively small portion of the energy is utilized for actual size reduction, and the major portion of the energy used is converted into heat. As a result, heat is generated inside grinding mills imparting to the ground product a higher temperature than that of the mill feed. In some cases, as for instance in grinding cement clinker and gypsum into finished cement, it may be desirable to keep this temperature increase within certain limits, to avoid any change in the properties of the product and, because consumers may specify a maximum temperature of the finished product for reasons associated, with the tulimate use of the cement. The actual proportions of heat and useful work are somewhat indefinite. Some tests have indicated that nearly all the energy is converted into heat, and. other investigators have found that they could account for "everything except the noise." Investigations sponsored by the American Institute of Mining and Metallurgical Engineers, and carried out with an adiabatic calorimeter, indicated that a surprisingly high 19 percent of the energy might actually be used for size reduc¬tion. However, for the purpose of the following discussion it will be assumed that: (Fig. 1) 10% is lost in motor and gears 10% is lost by radiation and convection from the mill body 10% is used for size reduction, and. that 70% of the energy input leaves the mill as heat in the ground. product. A typical example (Fig. 2) would be a 7x22-ft tube mill operating in open circuit, driven by a 400 hp motor, charged with 77,000 lb of grinding media and producing 70 bbl or 26,300 lb of cement per hour. Reducing this cement from a clinker size of 96 percent passing a No. 16 mesh sieve to a specific surface of 3,230 sq cm per gm (Blaine) will increase the temperature of the cement approximately 143F above the temperature of the feed, as explained later. If the tempera¬ture of the clinker therefore is 125F, the finished cement will be 268F, which in some cases may be too hot. : When cement temperatures approach a range during grinding where dehydration of the gypsum becomes a problem, a logical consideration would be some means of reducing the temperature before it attains the range conducive to gypsum dehydration. Regardless of the varying degrees of heat generated within the mill or mills during grindingto various finenesses, consideration of the maximum safe limit for any type of cement being ground, which may vary fromplant to plant, govern in refining the mill circuit to obtain a safe temperature range. All plants are not necessarily required to do the same cooling job, and may or may not use cement coolers following the grinding circuit. (Not discussed in this paper). In the past, various means have been employed for controlling this temperature increase, Such means have included water cooling of the outside of the mill shell; equipping the shell with cooling fins; injection of moisture inside the mill; ventilation through the mill; and., in cases of closed-circuit grinding, drawing cooling air through the classifier; the purpose in all such cases being to remove heat from the grinding system.

Jan 1, 1958

By Frank L. Gaddy

In this report, a description of mine practices, the preparation of roof bolts for laboratory experiments, the results of tensile-strength determinations, and a discussion of results of these tests are presented. Certain restrictions are recommended for roof bolts subjected to repeated bending, and two methods of complying with these limitations imposed by the restrictions are presented. The practice of bending steel roof bolts for installation in areas where the height of the opening was less than the length of the bolts required to support the immediate roof adequately has been adopted recently in several coal mines in lieu of sectional rods designed for that purpose. In addition, a few of these same mines have been reclaiming the bent rods and reusing them numerous times. The purpose of this study was to determine if these practices decreased the strength of such bolts and thus jeopardized the safety of the men working in these mines.

Jan 1, 1958

By Emma Smith, R. W. Guard

INVESTIGATION of the nickel-rich end of the Ni-Zr system has been prompted by an interest in the effect of small amounts of zirconium in high temperature alloys. Hansenl presents a hypothetical diagram based on the work of Allibone and Sykes,2 who investigated the system up to 44 atomic pct (55 wt pct) Zr by metallographic means. Since the alloys they used were melted in Alundum crucibles they were probably contaminated with appreciable amounts of aluminum. They found two compounds which they called Ni3Zr and Ni4Zr. Hayes, Roberson, and Paasche3 identified a compound NiZr (50 atomic pct Zr) with a melting point of 1470°C. Such a high melting compound is not compatible with the observation of Allibone and Sykes2 hat a eutectic is formed near 50 atomic pct. The alloys containing up to 60 atomic pct Zr were melted in an inert atmosphere in a noncon-sumable electrode arc furnace. Analysis of most of the alloys indicated negligible loss of zirconium. The alloys were examined in the as-cast condition and also after annealing for 6 hr at 1175°C (or 1000°C for the alloys between 25 atomic pct and 45 atomic pct). Metallographic specimens were etched using mixtures of HF-HNO3-H2O or acetic acid- HN0,-H,O. The specimens for the solidus determinations were wrapped in molybdenum foil and sealed in evacuated quartz tubes. Specimens to be heated above 1300°C were enclosed in zirconia tubes inside the quartz to prevent reaction with molybdenum. The solidus determinations were carried out by heating the specimens at various temperatures for a few minutes and then examining the interior structure metallographically to determine at what temperature melting began. The 150 mesh powders for X-ray analysis were annealed in an evacuated quartz tube for 2 hr at 540 °C to remove cold work. Alloys with 22.5 atomic pct Zr and 44.4 atomic pct Zr required annealing at 700 °C for complete recovery. The grains of both of these alloys were soft and rather ductile. Both Debye-Scherrer film patterns and spectrometer traces were made for each alloy using filtered copper radiation. Results and Discussion The presence of a substantial amount of second phase in an alloy with 1.1 atomic pct Zr indicated that the solid solubility of zirconium in nickel is somewhat less than 1 atomic pct. The a0 value for the face-centered-cubic matrix in the same alloy was equal to that of pure nickel, so that the solubility must be very small. This observation is as expected from the large atom size difference. Annealed specimens of alloys with 15.0, 16.7, 22.5, 28.6, 44.4, and 59.4 atomic pct Zr showed. micro-structures that were essentially single phase. When

Jan 1, 1958

By J. B. Clark, F. N. Rhines

brittlement or notch sensitivity progressively increases. Further, in contrast to results obtained with the impact test, the notch strength for the large specimens does not reveal a 500°F embrittlement range. The notch sensitivity as determined with the 0.3-in. specimen of 4340 steel given the stepped austenitizing treatment has been discussed elsewhere. This quantity as measured for the 1.1-in.- diam notch tensile test and given in Fig. 3, is taken to signify that reduced notch sensitivity is encountered in the 600" to 800°F tempering range for specimens given the stepped austenitizing treatment. The stepped austenitizing treatment may, there- fore, be of use in promoting deeper hardenability for a 4340 steel while at the same time giving reduced notch sensitivity in the high-strength range in which this steel is now being used. Acknowledgments The work reported was supported by the U. S. Navy Bureau of Aeronautics. The authors are indebted to the Bureau of Aeronautics for granting permission to publish results of this research and to N. E. Promisel, H. Hessing, and J. Maltz for their interest.

Jan 1, 1958

By J. J. Gilman

IT is well established that dislocations exist in crystals and account for crystal plasticity.' However, the origins of the dislocations are not clear. Among the means by which dislocations might originate are: a) through crystal growth accidents, b) by the collapse of condensed sheets of vacancies, or c) by stress-induced nucleation. Theoretical calculations' have indicated that the last means should require very high stresses in order to operate. The purpose of this paper is to show that the stresses around the tips of cracks are large enough to nucleate large numbers of dislocation loops. Specifically, it will be shown that (100) cleavage cracks in LiF crystals nucleate dislocations in regions of the crystals where dislocations did not exist previously. It is believed that the use of LiF for this investigation does not restrict the significance of the 1 results. In fact, it is believed that this complements and extends previous papers by the same author which dealt with metal crystals.10,14 The dislocations were detected by means of the etching techniques that were described in a previous paper by Gilman and Johnston.3 In that paper it

Jan 1, 1958

By W. L. Price

Recent publication of United States Bureau of Mines figures showed that the sand and gravel (3) industry is the largest single mining industry in the United States in term of yearly tonnage produced. The yearly production of over 500,000,000 tons per year now exceed bituminous coal production. This disclosure caught unawares many observers who have not been following closely the rapid-growth of this phase of mining. Along with this steady growth in production, the sand and gravel industry has gone through an accelerated and varied program of beneficiation in a period of the last ten years.

Jan 1, 1958

By James S. Browning

Domestic production of lithium minerals, source of the lightest metallic element, has increased from an average of 1,327 short tons of concentrate in the 1935-39 period to approximately 37,830 short tons in 1954. This rather phenomenal growth in production and use reflects growing industrial interest in the metal and its salts. This information circular has been prepared to summarize for the casual technical reader the reserve, mining, processing, and consumption situation pertaining to the mineral spodumene - the principal source of lithium. A relatively complete bibliography is included for those who may need more detailed information.

Jan 1, 1958

By Donald S. Colby

CARBON-BLACK shipments, which had declined in the latter art of 1953, remained low in 1954 until after settlement of the labor strike that occurred in the rubber industry in July and August. The production of new model automobiles in the last quarter of the year spurred the demand for rubber tires and consequently the demand for carbon black. Total shipments of 1,498 million pounds for the year were 4 percent below 1953.

Jan 1, 1958

By Irving Hartmann

At the 9th International Conference of Directors of Safety in Mines Research a paper6/ was presented describing the initial phases of research by the Safety in Mines Research Establishment at Buxton, England, on the remote control of timber fires with high-expansion foam plugs in a rock tunnel. The work received extensive publicity, and great interest was aroused by the implied possibility that the method might be used successfully to control coal-mine fires, which for various reasons cannot be approached and attacked by standard fire fighting measures and frequently require sealing extensive, valuable coal properties and lead to loss of production and coal reserves and occasionally loss of lives. To investigate the practicability of the foam-plug technique under American min¬ing conditions, with room-and-pillar-type extraction and multiple entries, the Bureau of Mines in 1957 began an investigation at its Experimental Coal Mine, Bruceton, Pa, In preparation for this work it was necessary to rehabilitate and reinforce an elliptical tunnel in the mine where studies had been made, many years ago, leading to development of a ventilation system used in the Holland Tunnels between New York and New Jersey, and in many other vehicular tunnels.

Jan 1, 1958