Search Documents

By Donald P. Schlick

This report presents a representative cross section of methods success- fully used to ventilate continuous-miner places as well as various factors that should be considered when selecting auxiliary ventilating equipment. Line brattice can direct fresh air to the active face reasonably well, provided that adequate area for installation is available. Continuous mining equipment, however, often restricts clearances to such an extent that proper installation of line brattice is impossible. Consequently, in many instances face ventilation is inadequate; therefore, many methods of auxiliary ventilation for continuous-mining equipment have been developed and have been discussed in this study.

Jan 1, 1963

By C. M. Bouton

Although much valuable work has been done in the study of dust explosions, the laboratory technique has not been developed to the point where the many factors involved can be properly controlled, and thus where really fundamental information can be obtained. This paper presents a brief discussion of the difficulties encountered in fundamental work on dust explosions, a description of apparatus intended, to overcome some of them, and an account of some results obtained. FACTORS INVOLVED IN DUST EXPLOSIONS The more important factors pertaining to the dust cloud itself which are known to determine the phenomena of explosions are (1) the kind of dust; (2) its fineness; (3) its concentration in the exploding cloud; and (4) the nature of the interior motions, or turbulence, of the cloud before and during the explosion. These factors are arranged in what seems to be an ascending order of complexity. The kind of dust is the factor most easily subject to control. The fineness of the dust at first sight seems to be a controllable factor, but when it is recalled [that] most explosible dusts are mixtures of particles of continuously varying sizes so small as to pass through the finest woven sieves, and therefore difficult to separate either for purposes of analysis or experiment, the fineness is seen to be a factor difficult to control accurately.

Jan 1, 1929

By John M. Devine

The oxygen bomb-is used extensively for determining sulphur in petroleum, although it has been suspected that the results obtained with this method are somewhat lower than the true varies. In this paper are compared the results given by the oxygen-bomb and Carius methods, the latter being generally accepted as the standard procedure for the determination of sulphur in organic compounds. The Carius determinations given hero were made in connection with a special study of this method.4 Only petroleum oils of the less-volatile type are covered in the present work. Summary and Conclusions. When used with oils containing 2.3 to 0.15 per cent of sulphur the oxygen-bomb method gives results that are consistenly if slightly lower than those obtained with the Carius method. This variation, for the oils used, amounts to 3.1 per cent (on tae basis of sulphur present) for the sample containing 2.47 per cent of sulphur, and gradually increases (as the percentage of sulphur in the oils decreases) to 7.3 per cent for the oil containing 0.15 per cent of sulphur. With the oils studied the presence of ammonium nitrate in the bomb does not influence the results materially.

Jan 1, 1928

By Raymond B. Ladoo

Cne of t·: . .:: i::,portt recent developrr.ents in the feldspar industcy l:.a.s beer. tl:.e r,:ipid. rise of Ne·N H.v-:psr.ire as a. feldspar producing State. Tl:.e unusual size and purity of t: e deposit now 'being worked ne3.r Keene, and tr.a i.nproved metl:.ods ot:' rr.ining srd ir,illing used l:.ave been responsible foe tt.is situation. ti'eldsp'.:l. w'ls occ':tsiona.lly produced sorr.e ye1rs ago in srr.a.ll (tuantities in New Hrunpshi :e, but t::.e State had not been considered a producer of" feldspar ui til lS3l. In the s::ring of tr .. at yea!', t:.e '[eane iic Products co. of Keene, N.H., beg3Il in a srr.9.ll way tl:e production of feldspar fro:n t1eir property in Gilsum, H.H., whicr. l-.a.d long been opera.tei a.s a :tl.ca mine. The purity of the feldspar at enoe '\ttracted f''.lvorai)le attention. and tt.e production of crude ore rapidly in­ cre'.\sed. Early in 1922, a new company, t'he Golding-Keene Co,

Sep 1, 1922

By D. N. Nilsen

The U.S. Bureau of Mines investigated the use of unsupported liquid emulsion membranes (LEM's) for the extraction of copper from relatively dilute aqueous solutions (=0.3 and 2.5 g/L Cu), The performance characteristics of the three main unit operations of an LEM circuit (emulsion generation, metal extraction, and emulsion breaking) were assessed in laboratory-scale batch tests. In single-stage extraction tests using 2.5-g/L Cu feed solution, emulsion membranes extracted up to 94 pct of the copper from solutions without pH adjustment and 99.7 pct when the pH was maintained at about 2.5. Simulated two-stage crosscurrent and countercurrent circuits extracted all but 3 and 4 ppm of the original copper content, respectively. Extraction data from solutions containing mixtures of metals indicated a strong preference for Cu2+ extraction when oxime-type extractants were used in the LEM; however, some coextraction of Fe 3+ and Zn2+ was experienced. An electrostatic coalescer was used to break the copper-loaded emulsions for separation of the component phases. Up to 96 pct of the contained stripping solution (internal solution) containing the extracted copper was separated from the organic phase of the emulsion membrane. The recovered organic phase was recycled without apparent problems.

Jan 1, 2010

The current procedure for measuring the concentration of respirable coal mine dust is as follows. Each filter is preweighed by the filter manufacturer to ±0.1 mg. Following sampling with the Coal Mine Dust Personal Sample Unit (CPSU) at 2.0 L/min, the filter with coal mine dust is sent to MSHA for weighing. The current MSHA procedure for weighing respirable dust samples uses a Mettler Model AE163 analytical balance in conjunction with an automatic weighing system with a precision of ±0.02 mg [Tomb 19901. Each balance is calibrated twice per day. Quality control for the automatic weighing system includes the systematic weighing of one in eight filters on a second Mettler AE163 balance. Tolerance is set at ±0.1 mg between the two weighings of the same sample. Weights are truncated at the 0.1 mg level (e.g., 3.457 mg is truncated to 3.4 mg) [Bowman et al. 19851. The difference of the two truncated weights is then recorded as the weight of coal dust deposited. The respirable concentration (mg/m3) is computed by multiplying by a correction equal to 1.38 and dividing by the volume of air sampled (2.0 L/min x sampling time [min]).

Jan 1, 1997

By John R. Shattuck

Preliminary examination of the McCormick chromite property was made by the Federal Geological Survey and the Bureau of Mines during the spring and summer of 1943. In October 1943 an exploratory project was undertaken by the Bureau in cooperation with the Survey and was completed in February 1944.The urgent need during the war for high-grade lump chromite such as produced at the McCormick mine, was one of the pertinent reasons for the project. The McCormick mine is situated about 12 miles southwest of the town of Sonora, in the foothill belt of the Sierra Nevada Mountains, Tuolumne County, Calif. The chromite occurs as irregularly shaped lenses in masses of dunite contained in a steeply dipping, sheared, serpentinized zone of peridotite, near a contact with granodiorite.

Jan 1, 1949

By A. U. Miller

The added hazards to mining incident to oil and gas wells penetrating the coal measures in proximity to mine workings , have long been recognized in those fields where the extraction of oil , gas , and coal , has been in progress for a number of years . The history of these fields is replete with stories of serious mine fires , explosions , and miraculous escapes from both fires and explosions due to either oil or gas finding its way into the mine workings through the strata , or by mining into an unknown or uncharted and abandoned oil or gas well that had not been properly plugged . The Director of the Bureau of Mines , in response to numerous requests from coal operators and oil and gas operators , called a meeting in 1913 to discuss necessary precationary measures to take when drilling oil or gas wells through workable coal beds and to try, if possible . to formulate a set of regulations that might serve as a guide to those persons preparing regulations covering the drilling of oil and gas wells in the various coal producing States . This meeting was attended by representatives of the coal , oil , and gas industries , State geologists , State mine inspectors , and representatives of the Bureau of Mines . A committee was appointed to prepare a set of regulations , which was later published as U.S.Bureau of Mines Technical Paper 53 ; the discussions and results of the meeting werepublished as U. S. Bureau of Mines Bulletin 65 . Later , the American Institute of Mining and Metallurgical Engineers appointed a committee to draft a model law for the use of the legislature of any State concerned . This committee made its report on April 27 , 1928 . Several of the coal mining States now have more or less comprehensive regulations governing the drilling of oil or gas wells through workable coal beds , others have regulations that are inadequate , while some have no regulations . The State of West Virginia recently enacted a law containing reg lations which are the result of a comprehensive and careful study of the problem .

Nov 1, 1929

By Isaac A. Zlochower

This paper presents data on the limiting (minimum) oxygen concentration (LOC), in the presence of added N2, of methane (CH4), propane (C3H8), ethylene (C2H4), carbon monoxide (CO), and hydrogen (H2), and some of their binary mixtures. It also addresses the issue of the flammable concentration (flammability) limits of these pure gases in air. The study is based on spark ignited explosions in large, spherical laboratory vessels (120-L and 20-L) using a 7% pressure-rise criterion for explosion propagation. The results of the study are compared with the older values which used long flammability tubes with a diameter >5 cm together with visual evidence of substantial upward propagation. They are also compared to results reported recently using a 12-L spherical flask with a visual flame propagation criterion. Finally, they are compared to results reported in Europe using more modest flammability criteria and smaller chambers. The findings reported here show excellent agreement between the 120-L and 12-L results, good agreement with the 20-L results, and reasonable agreement with the earlier flammability tube values for the lower flammability limits. They disagree, however, with the more conservative European values. These results and those from the 12-L experiments also feature lower LOCs than are given by traditional flammability tubes. A model for the LOCs of such fuel mixtures based on the Le Chatelier mixture rule for lower flammable limits is seen to reasonably fit the observed results on binary mixtures and can accommodate more complex mixtures as well. One such set of ternary mixtures containing CH4 and 1:1 CO:H2 is well fitted by the model.

Jan 1, 2009

By R. L. Schmidt

The Methane Control and the Respirable Dust Groups at the Twin Cities Mining Research Center (TCMRC) cooperated recently in obtaining production samples of approximately 1 ton each, from the loading conveyors of a ripper, a borer, and a loading machine in conventional development headings. These samples were sized, in four stages, from plus 4 in to minus 10 µm. The conventional product had the least fines of the three production methods. The borer product had more fines than did the ripper product, but it also had a greater amount of large pieces. All three products, as sampled, had essentially the same amount of minus 10-µm particles. Photomicrographs and surface?-area comparisons were made. Gas -adsorption, surface-area determinations on particles under 37 µm give essentially the same value. Surface-area calculations, assuming spherical particles and no porosity, give a smaller area to the conventional product.

Jan 1, 1972

By S. E. Khalafalla

The Bureau of Mines has used colloidal solutions of magnetite in a magnetic field to segregate nonmagnetic materials such as nonferrous scrap metals and to concentrate precious minerals. Conventional magnetic separation relies on the inherent magnetic susceptibility of the material to be separated and may be designated as magnetic separation of the first kind the medium of separation rather than the separated particles are made magnetizable, a new system of gravity separation results. In this new magnetic separation of the second kind, a magnetic fluid rather than air or water acts as the separation medium. The same force that attracts magnetic objects in separations of the first kind also attracts the entire separation medium in separations of the second kind, thereby creating a reactionary force of equal magnitude in the opposite direction. This force, sometimes called the levitation force, can be made to segregate nonmagnetic particles in a flowing stream according to their specific gravity. The technique has been applied to segregate nonferrous metals from automobile and appliance shredders and mixed scraps. The system has also been used to upgrade diamondiferous jig concentrates from certain river gravels in order to facilitate the sorting and recovery of their diamond content.

Jan 1, 1981

By D. Harrington

In recent years over 100,000 persons have been killed annually in the United. States by accidents; about one-fifth of these have been workers in some of our industries; about one-third have been killed by motor vehicles; about another third have mot death in home accidents, chiefly falls, burns, scalds, explosions, poisons, asphyxiations, suffocations, cuts, scratches, and so forth; and the rest have been killed in public accidents, excluding those caused by vehicles but including accidents on railroads or electric cars, drowning, and deaths by firearms and. other means. Definite statistics on nonfatal accidents are not readily available, but at least 10,000,000 fairly serious accidents probably occur in the United States annually. The latest industrial-accident statistics are obtainable from 1935 National Safety Council publications, in which annual industrial fatalities are divided about as follows (in round numbers): Agriculture, 4,500; trade and service, 4,500; construction, 3,100; transportation and public utilities, 2,900; manufacturing, 2,600; mining, quarrying, petroleum, etc., 1,900.

Jan 1, 1938

By E. J. Gleim

In April 1932, the Bureau of Mines published Information Circular 6595, entitled "Data in Reference to Installation of Cables in Shafts and Boreholes", in which were described methods followed in various sections of the United States when electrical circuits are taken into mines by means of cables suspended in shafts and boreholes. In view of the present tendency to extend high-tension cables along entries and passageways from the bottom of the shaft, borehole, or other point of entrance to coal mines rather than over the surface, it is deemed that the various methods of installing such cables deserve careful consideration, particularly in mines in which gas and coal dust contribute to explosion hazards. This is especially true of localities where there is an inclination to restrict the extension of 2,300- and 4,000-volt circuits into the mines. Probably it is feared that accidental contact with the cables of such circuits may result in more serious shock than with lower voltages; also, it is possible that new circuits are regarded merely as explosion hazards additional to those already existing, regardless of the manner in which the new circuits may be installed. It is the firm belief of some engineers that the circuits can be installed so that they will not be damaged by wrecks or roof falls, thereby eliminating the hazard of explosion from this source while at the same time making the chance of accidental contact remote if not impossible. Moreover, some believe that fire hazards from direct-current systems can be reduced by keeping motor-generator sets close to load centers. Thus, although the alternating-current circuits would be lengthened, the size and extent of direct-current circuits would be kept to a minimum.

Jan 1, 1939

By L. C. IlsLey

"The underlying principle of the storage battery was discovered within the memory of many still living, hence storage-battery locomotives, which were made possible by this discovery, represent a still more recent development. The Journal of the Franklin Institute for December, 1883, gives an account of the building of an electrical omnibus by The Electrical Storage Battery Co., of Millwall, London, This, if not the first, was among the first attempts to, use the storage battery as the source of energy for locomotion.During the period 1888 to 1893 occasional attempts were made to apply this idea practically, but not much was achieved along useful lines.. The progress during the next, 15 years was slow, and little success was achieved. Therefore, the last two decades may be considered the successful development period of the storage-battery locomotive.In coal mining, the application of the storage-battery locomotive is chiefly in gathering service in competition with animal or cable-reel locomotives. The locomotive delivers empty cars to the rooms or working places where the coal is being mined and hauls the loaded cars from the rooms. The length of haul depends upon the distance of, the junction point from the active workings of the mine. As a rule the haulage from the junction point to the foot of the shaft or bottom of the slope is done by trolley locomotives, but in some instances where the grades permit this main-line haulage work it: performed by storage-battery locomotives.As the place storage-battery locomotives occupy with respect to safe haulage in gassy mines appears to be misunderstood, it is the purpose of this paper to clarify this point.Those who originally designed storage-battery locomotives had no thought of safety in mind and it is just as well that they did not, as these early types of storage-battery locomotives with open controller open motor, open rheostats, flimsy headlights, and crude wiring were very dangerous electrically and not at' all suitable for use in a gassy mine. These locomotives, however, were placed in mines in which open lights were permitted and they replaced considerable animal haulage. Later they were gradually introduced in mines where closed lights were used, but in most cases these mines were not extremely gassy."

May 1, 1928

By H. P. Greenwald, G. E. McElrey

"Part IV.- The Resistance Caused by Right-Angle Bends. IntroductionThis paper deals with the fourth phase of an extensive research on coal-mine ventilation factors. A comprehensive report of the entire work is in course of preparation, but abstracts of the various chapters are being prepared in order to make the major results public as rapidly as possible. Parts I, II and III were issued as Serials Nos. 2621 (July 1924), 2647 (October 1904) and 2671 (March 1925) and dealt with the resistance of unobstructed entries, the resistance due to mine cars and, the resistance of timbered entries respectively.Description of the Tests With the last cutthrough between the two butt entries of the test section in the Experimental Mine open, the air flow was deflected, around two right-angle bends in the same direction, the butt entries being 50 feet center to center and approximately 6 by 9 feet in cross section. Each bend had a dead end opening off of it; that at the first bend was in the direction of flow and that at the second bond was at right angles to the flow. For a primary test condition the inner corner of each bend was trimmed square and the dead ends were closed off with board brattices set flush with the line of the cut-through.The two corners of the first band were, then modified both independently and in conjunction. Various modifications of both bends in conjunction were also tested with rather surprising results as to the effect of conditions at the first bend, upon the pressure losses at the second. To confirm the theory developed to fit these results a series of tests were made to give a direct comparison of the -pressure losses as between two bends with the air flow deflected in the some direction at each and with the air flow deflected in opposite directions. The former is designated ""double"" and the latter a ""reversed"" right-angle bend. This series of tests was conducted, however, on the bends at one of the intermediate cutthroughs at which the flow could be deflected us either direction at the second, bend. Here also the average cross-section was 6 by 9 feet and the bends were 50 feet apart."

Jan 1, 1928

By P. W. Jeran, M. C. Irani, Maurice Deul

This Bureau of Mines survey of methane emissions indicates that total daily emissions have declined from 227 MM ft3 in 1971 to 214.7 MM ft3 in 1973. The highest average daily emissions in million cubic feet per day observed in U.S. bituminous coal mines were, in decreasing order, Monongalia County, W. Va. , 40.7 ; Marion County, W. Va. , 23.1 ; Buchanan County, Va. , 22.1; Washington County, Pa., 12.4; Greene County, Pa., 11.7; McDowell County, W. Va. , 11.4; Cambria County, Pa., 9.8; Jefferson County, Ala. , 9.5; Wyoming County, W. Va., 6.0; Marshall County, W. Va., 4.8; and Indiana County, Pa., 4.8.

Jan 1, 1973

By Ann G. Kim

Methane in coal constitutes a serious hazard in coal mining. Draining the methane in advance of mining can mitigate this hazard, conserve energy, and offer economic benefits. This Bureau of Mines report evaluates the Pittsburgh coalbed in Greene County, Pa., to determine if advance drainage is feasible. The gas content of virgin reserves in Greene County is estimated at 100 to 200 ft3/ton, a total of over 370 billion ft3 of gas in an area approximately 310 mi2. Because of the similarity to natural gas, drained coalbed gas could be recovered and added to pipeline supplies of natural gas. The value of conserved gas would offset the cost of drainage and extend energy resources.

Jan 1, 1975

By J. B. Gayle

Because economic and geographic factors have focused particular attention on the use of anthrafines in blends containing Lower Kittanning coal as the low-volatile component, samples from this particular bed were selected for experimentation whenever practical. Carbonizing tests were carried out in accordance with standard procedures, using the Tuscaloosa and sole-heated ovens. Most of the results are in general agreement with those reported by previous investigators. Specific findings are as follows: (1) The effectiveness of anthrafines in reducing coal expansion is such that even highly expanding, low-volatile coals can be carbonized safely with suitable additions of anthrafines and careful control of charge density. (2) Increases in coke size, resistance to shatter, and apparent specific gravity appear to be characteristic for additions up to approximately 15 percent to a fixed base blend. When anthracite of minus-48-mesh size was used and the proportion of low-volatile coal simultaneously increased, these indexes increased only slightly or remained substantially constant. (3) No increase in breeze formation was noted for additions in amounts up to 15 percent. (4) Abradability of coke was increased by additions of anthracite of No. 5 Buckwheat size, but it either decreased or remained sub¬stantially constant when the inert was ground to pass a 48-mesh screen.

Jan 1, 1956

By R. V. Ramani, K. V. K. Prasad

"This paper was the subject of a cross-disciplinary presentation under the chairmanship of Dr A.M. EdwardsManagers need quality information for effective decision making. This demand, at the present time, is being fulfilled by the increased use of computers via information systems, decision support systems and management information systems. The idea of incorporating intelligence into computers to aid decision-makers has been evolving for over two decades. In recent years, significant progress is reported on applications to business and sciences. In engineering functions, the Artificial Intelligence approach that seems to have great potential is the application of Knowledge Based Systems.The primary objective of this paper is to identify domains in mining engineering where application of knowledge based systems could be beneficial. Incorporation of the expertise required during the analysis and interpretation stages of an engineering design problem through knowledge based systems is recognized as an area of significant benefit. To this end, the components of knowledge based systems for mine ventilation and strata control design are described. The potential applications and limitations of knowledge based systems are outlined. IntroductionCorrect decisions are the key to success in any enterprise. Scope of decisions varies with the echelons of management hierarchy. The decisions of top management are strategic, relating to the long-term future of the organization. In a mineral organization, these deal with such issues as the acquisition of a new mineral property or the diversification of the business to exploit additional markets. At the operational level, a manager is concerned with decisions pertaining to day-to- day eventualities related to production activities and other short-term needs. In either case, the prerequisite is the timely availability and use of information. The difficulty involved in decision-making depends on the situational aspect. In. many cases, the decisions to be made under given conditions are fairly straight-forward and standard. This may be due to experience gained from decision-making in similar situations in the past. In fact, many decisions in operations management are either repetitive or routine."

Jan 1, 1989

By S. J. Page, J. A. Organiscak

Dust surveys were conducted around small truck-mounted rock drills operating at surface coal mines to assess their airborne respirable dust generation and in-service dust control methods. Of four out of seven drills sampled, respirable dust concentrations measured around the drill deck ranged from 8.68 to 95.15 mg/m with3concentrations ranging from 1.37 to 2.69 mg/m at distances 12.2 to 30.5 m downwind of these drills. The other3drills had noticeably lower respirable dust concentrations measured around the drill deck at or below 1.30 mg/m.3Rotoclone-type dry dust collectors were commonly used with dust being emitted from around the drill deck shroud, collector exhaust, and collector fines dumping. Wind speed and direction was also a factor in the dust concentrations measured on the bench. Dust control modifications were made to three rock drills to reduce their airborne dust emissions. Dust controls tested included water injection into the Rotoclone exhaust, Rotoclone exhaust extension, improved sealing of drilling deck shroud, shrouding the Rotoclone hopper dump process, and wet drilling. These control techniques showed noticeable improvement in dust concentrations measured around the drills. Finally, repositioning the drill operator showed that operator dust exposure can be improved by avoiding the dust cloud around the drill.

Jan 1, 1995