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By E. D. Eastman

The recent determination by Eckman and Rossini of the heat of formation of sulphur dioxide appears to be of much greater accuracy than any previous measurement . The value obtained by them , 70,940 cal . , is in good agreement with that of Thomsen ( 71,080 ) , but differs by about 1,700 calories from Berthelot's result ( 69,260 ) , and by 1,940 calories from the provisional figure ( 69,000 ) adopted by Lewis and Randall in their studies of the free energies of the sulphur compounds . This large discrepancy suggested the desirability of a recalculation of the free energy of sulphur dioxide . In addition it is now possiblt to fix the specific heat of S₂ gas with greater certainty than at the time of the original calculations . These two changes are incorporated in the recalculations described below , and directly affect the values of AH , and the Ar terms in the free energy equation . In the determination of the integration constant of the latter equation , the free energies and specific heats of water vapor and the oxides of carbon are required as auxiliary data . In this work these are based , with certain exceptions , upon the equations previously deduced , which differ appreciably from the corresponding equations of Lewis and Randall . 56 · The principal equilibria employed below , and the plan of calculation , remain the same as in the calculations of Lewis and Randall . Before beginning this revision a search of the literature was made , extending to August , 1930 , for studies of additional equilibria . Only one reaction was found that gives promise of increased accuracy . This is the equilibrium of sulphur dioxide with copper , cuprous oxide , and cuprous sulphide . In this case , however , certain of the subsidiary data are lacking , and until they become available , the existing studies of the equilibrium in this system can not be successfully utilized . The changes in the numerical data mentioned above , especially in the thermochemical constants , are therefore solely responsible for the rather significant differences of the revised from the original values of the free energy .

Apr 1, 1931

By Manuel Gomez

The purpose of this study was to evaluate the feasibility of using statistical response surface regression analysis to predict the sulfur and ash distributions and the washability characteristics of coal along a seam in advance of mining. Prediction equations were developed with experimental data from channel, bench, and core samples from the Pittsburgh coal seam in Greene County, Pa. It was not possible, with the available experimental data, to construct mathematical models to predict ash and sulfur concentrations between sample points. In the authors' opinion, however, the good agreement between experimentally determined and predicted values at given sample points demonstrates the usefulness of the method. More input data, such as geologic information, seam characteristics (rock-to-coal ratio), petrographic analysis, and chemical data, would perhaps make it possible to predict sulfur and ash concentrations and washability characteristics between sample points.

Jan 1, 1970

Develop quieted, hand-held pneumatic percussion drills that can replace standard hand-held drills in many underground mining applications. The Problem Percussion drills are the noisiest machines used in underground mines; noise levels of 115 to 120 dBA are common, requiring the use of hearing protectors and limiting the time a miner is permit-ted to operate the drill during an 8-hour shift. Hand-held pneumatic percussion drills pose a particularly difficult problem because the operator cannot be isolated from the noise source (e.g., an acoustical cab), and alternative technologies for drilling roof bolt holes and blastholes in tight quarters are not readily available.

Jan 1, 1984

By O. P. Hood

The smoke problem means different things in different places . In the neighborhood of industrial plants , especially smelting plants and cement plants , the term " smoke " is applied to material discharged from these plants , consisting of a mixture of solid particles ( dust ) , fume which has condensed from vapors , and gases of various kinds that are produced in the operations . In the ordinary use of the word , however , " smoke" refers to the visible material which escapes from the burning of coal . White smoke usually owes its color to small drops of water which have condensed from the water vapor that it formed in the burning of coal . When smoke is black, the color is due to unconsumed particles of carbon and usually when the smoke problem is spoken of , it is this black smoke produced in the burning of coal that is referred to , Many inquiries in regard to smoke are addressed to the Bureau of Mines , and the following brief summary has been prepared as covering the usual questions . For references to the smoke problem in England , I am indebted to a recent interesting paper on this topic by David Brownlie .

Feb 1, 1922

By Robert H. Merrill

A method of determining the strength of a mine roof layer in place is described in this report. The method was tested on a limestone roof layer 50 feet wide, 100 feet long, and 20 inches thick. In place measurements were accomplished by introducing air under pressure into a separation between the layer and the overlying roof, and as pressure was increased, the corresponding strain and deflection of the roof layer were measured until the roof failed. The ultimate strength of the roof agreed with the tensile strength of the roof rock (modulus of rupture) as determined in the laboratory; the modulus of elasticity as measured in place did not agree with the laboratory-determined values; the deflection and tensile strain in the layer in place showed good agreement with the theory of a body-loaded beam clamped at both ends. This procedure for determining the strength of a mine-roof layer is safer and less costly than successively widening a roof to failure. For example, it would have been necessary to mine the room to a width of 114 feet and a length of 228 feet to produce failure in this roof layer. The method is not necessarily limited to limestone; any thinly bedded rock type can be tested by this procedure when there is an open parting over the mined area.

Jan 1, 1958

By EINAR M. ARENTZEN

This information circular. deais primarily with an engineering descrip- tion of a type of longwall cutting and loading machine developed by Eick- hoff Maschinenfabrik, Bochum, Germany..: This machine is supposed to have been developed and tested during the latter part of 1941 and early 1942. The only source of information is con- tained in certain literature and engineering data, with drawings which were acquired by the Allied Military Authorities when Germany was occupied; and the information will have to be limited because the writer has not seen the machine in the factory or in operation. However, the information may be of interest to the coal-mining industry in this country, and for this reason our Government has decided to publish the data procured so far. The Eickhoff cutting and loading machine is particularly suitable for the longwall mining system. It can only be used under that type of mining system and is not suitable for the more common type known in this country as room-and-pillar work. The material for the description of the machine and its operation was compiled and translated from German drawings and operating instructions. These detailed drawings and instructions are on file with the Bureau of Mines and are available for inspection by any responsible person interested in the details of the construction of the machine.

Dec 1, 1946

Design a high-production coal mining machine with inherent low dust generation and low frictional ignition potential. Approach Constant depth linear cutting (CDLC) provides a longterm solution to excessive dust generation from shearers and continuous mining machines through new design of the rotary drum culling system. Problems with rotary drum systems, which must be eliminated to control the dust generation at the source, include the effect of a con¬stantly varying depth of cut using fixed bit spacing, secondary fragmentation of already broken coal and, frictional heating of bits and entrainment of dust by fanning action due to high drum rotational speed, Each bit on a rotary drum enters the coal face at zero depth of cut, goes to some maximum depth at the horizontal centerline during sump, and exits at zero depth.

Jan 1, 1989

By Erle C. Donaldson

The pendant drop interfacial tensiometer is being used to study interfacial phenomena that influence the production of crude oil. A description of the instrument showing the modification of the cell and cell holder is presented. The modified cell and cell holder allow formation of a precise and reproducible drop size, and the image of the drop is easily alined and focused. Interfacial tension measurements and observations of film formation can be conducted at various temperatures with the jacketed cell.

Jan 1, 1967

By L. W. Higley

Procedures were developed for reclaiming high-temperature alloy scrap in the form of standard cobalt-base alloy. A cobalt-base, multicomponent, high- temperature alloy, such as S-816, can be successfully melted from scrap, and its specified chemical composition can be retained. Induction furnace melting in a controlled atmosphere was used to obtain ingots that were subsequently fabricated by impact forging to provide specimens for heat treatment and testing. Of the numerous metal elements in S-816 alloy, only small quantities of molybdenum were lost in the melting operation as finally developed. Test results indicated that the scrap material, after melting, forging, and heat treatment, was equivalent in room-temperature tensile strength, in high-temperature creep and stress-rupture properties, and in chemical composition to commercially produced S-816 alloy made from virgin material.

Jan 1, 1963

Lower the respirable dust exposure of longwall shearer operators by isolating and con-fining the dust cloud near the face. Approach Install conveyor belt screens at various locations on the body of the shearer to contain and hold the dust cloud toward the face side of the machine. This approach provides a cleaner air split in the walkway, over the shearer operators. How It Works On most longwall shearer sections, the dust exposure of the shearer operators is primarily attributable to the machine it-self. The dust cloud originates at the face, and the exposure of the operators depends largely on how quickly this dust spreads into the walkway. Conveyor belt screens placed on the gob side of the body of the machine can reduce the amount of dust which spreads out into the walk-way. In addition, belting may be installed over any open spaces between the shearer under-frame and the panline to prevent conveyor dust from boiling out into the operator's walkway.

Jan 1, 1981

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

By F. W. Cox

Exhaust emissions were measured from 25 aircraft turbine engines using Jet A fuel. Analytical apparatus, procedures, and results are described. Carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, and aldehydes were measured at engine operating modes representing power levels used in airline operation. Carbon monoxide, hydrocarbon, and aldehyde emissions were highest at idle and lowest at takeoff; oxides of nitrogen were lowest at idle and highest at takeoff. Of the total oxides of nitrogen emitted, nitrogen dioxide constituted from 10 to 100 pct, depending on the exhaust gas temperature. Engines retrofitted with smoke-reducing burner cans produced less carbon monoxide, hydrocarbon, and aldehyde emissions, and slightly more oxides of nitrogen then engines with standard burner cans.

Jan 1, 1972

By D. Harrington, C. W. Owings

Each year at least one and in some years several explosions are reported as having resulted from firing of mudcapped shots in coal mines; undoubtedly a number of small or local explosions occur that are not reported; in addition there are numerous accidents, some of them fatal, attributable to this reprehensible blasting practice. It is surprising that so few explosions and other accidents from this cause occur since the practice of firing mudcapped, Even in gassy "adobe," "dobe," "sand blast," or "bulldozed" shots is widespread. mines where general blasting is safeguarded by being done with permissible explo- sives, rocks or bowlders frequently are blasted with mudcapped shots of dynamite; even if permissible explosives are used, this type of shooting is dangerous. The usual method of preparing a mudcapped shot is to place the explosive, either in loose or cartridge form, with the detonator or "cap" on top of a piece of rock or coal and cover it with several handfuls of moist clay, loam, sand, or When the shot is road dust; in many cases there is no covering of any kind. fired a dense cloud of dust, together with an intensively hot fleme, are thrown into suspension, and if the dust is explosive or ignitable an explosion or igni- tion is likely to result practically simultaneously. The presence of gas greatly increases the explosibility of the dust, as well as the probability of an ignition. Every shot, of any known explosive, fired in a coal mine without having the charge properly confined in a drill hole and tamped with incombustible stemming to the collar of the hole, is capable of initiating an explosion that may cause the death of every man in the mine. Attention has recently been directed to this unsafe practice by an explo- sion resulting from a flagrant disregard of safe blasting practices in one of our The mine had been idle for several years most productive coal-mining regions. and was being prepared for reopening on a different system of mining. Six to 10 inches of bottom coal had been left in place during former mining operations, but in the new system it was felt desirable to remove the bottom coal left in certain parts of the mine. Instead of drilling holes in the coal, loading them, and fir- ing in the usual safe manner, five or six charges of dynamite were placed on top of the coal in each of several rooms; and while the men were at the mouth of the

Aug 1, 1929

By Seymour Wasserman

To develop noise control designs for secondary crushers in Taconite plants. Taken into consideration: 1. Acoustical criteria 2. Day-to-day operational considerations and maintenance accessibility 3. Materials of construction 4. Adaptability of design to other Taconite plants having crushers 5. Cost of noise control treatment.

Jan 1, 1977

By F. D. Osgood, H. M. Cooper, A. C. Fieldner

The analyses in the tables are arranged geographically with respect to county and towns, and are grouped as follows: l The proximate analysis--moisture, volatile matter, fixed car bon, and ash; 2 The ultimate analysis-carbon, hydrogen, nitrogen, oxygen, sulphur, and ash; 3 The calorific value of heat of combustion; 4 The softening temperature of ash, when such determinations were made. Ultimate analyses are given in three conditions-namely, (1) as received, (2) moisture free, and (3) moisture and ash free Proximate analyses and heating values are given generally in one condition -namely, as received, some are in two conditions, as received and moisture free.

Jan 1, 1928

? A roof bolter reaches for a lever while guiding the drill with his other hand. Since he's watching the drill and many of the controls look and feel alike, he hits the wrong control and crushes his hand. ? Six hours into the night shift, an ore truck driver dozes off. The truck plows over the berm and down into the pit. ? Fleeing a afire, a face crew sees smoke in the intake entry. Assuming the fire is ahead, they cross over to another entry, but soon encounter even worse smoke. These very different accidents have at least one factor in common: the human factor. The actions, decisions, thoughts, or perceptions of one or more humans contributed to the accident. These are just a few examples of safety problems researched by the Human Factors Group of the Pittsburgh Research Center, U.S. Department of Energy.

Jan 1, 1998

Lower the respirable dust exposure of longwall shearer operators by use of a modified head to tail cutting sequence. Approach Modify the cutting sequence of double-drum shearer operations cutting unidirectionally head to tail, so that the tailgate drum is used to mine the entire coal face except when cutting out at the head. This approach would place the primary dust generating source, the cutting action of the drum, on the return air side of both shearer operators. How It Works Currently, 75% of the double-drum shearers in operation employ a unidirectional cutting sequence. On half of these operations, the primary cut is taken as the shearer travels from the headgate to tailgate ends of the face, with roof support to be advanced on the intake air side of the shearer. Typically, the leading (tailgate) drum is taking a full cut during the head to tail pass and the trailing (headgate) drum is cutting bottom coal. In this mode of operation, the dust generated by the trailing (headgate) drum can spread out into the walkway, and increase the respirable dust exposure of both head and taildrum operators. As an alternative, if the trailing drum is "free wheeling" or cutting minimal coal during the head to tail cut, and bottom coal taken by the tailgate drum during the tail to head clean-up pass, both operators are able to work on the intake air side of the primary dust generating source (drum) except when cutting out at the head. This modified cutting sequence would save wear on the conveyor and help to eliminate overloads, as well as reduce the respirable dust exposure of both shearer operators. This modifcation is only applicable to long-wail operations currently cutting unidirectional head to tail, and to those operations where this unidirectional cut would not produce operating constraints.

Jan 1, 1981

By J. A. Herdlick

"INTRODUCTION The Bureau of Mines began a broad program of exploration of various proportion in the Pine Creek area of the Coeur d'Alene mining region in the fall of 1943. As a part of this project, exploring was done at theLittle Pittsburg property in 1945. The work included driving a 500-foot crosscut from the No, 6 level and drilling four diamond core drill holes to test the behavior of the Little Pittsburg vein at depth. This report presents the data obtained by the Bureau.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources, to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyses samples and performs beneficiation tests.The Bureau's exploration of the Little Pittsburg vein was one of the activities of the Albany Division of the Mining Branch, S. H. Lorain, chief. The project was started by R. M. Gammell, mining engineer, and was continued by the author and J. R. Reynolds, assistant mining engineer.The chemical analyses included in this report were made at Reno, Nov., under the direction of A.C, Rice, acting engineer in charge, Rare and Precious Metals Experiment Station, Bureau of Mines.The cooperation and assistance of the management of the Denver Development Co. is gratefully acknowledged, in particular that of C. E. Nugent, who made available much of the operational data included in this report."

Jan 1, 1947

Increase the safety of operators of front-end loaders by providing a means of monitoring the machine's stability. Approach Through a research contract, the Bureau of Mines developed a front-end loader stability indicator which provides the machine operator with a reliable, easily interpreted display assessing the stability of the machine. How It Works Statistics show that front-end loader accidents are the largest single category of machinery-related accidents in the surface mining industry. Many of the fatalities resulting from these accidents occur when front-end loaders rollover and either crush the operator who is trapped within the cab or strike the operator who is trying to jump to safety. Although rollover protective structures (ROPS) are required by law on front-end loaders to protect operators in the case of a rollover, these do not prevent the actual rollover from occurring. In fact, the operator has no way of evaluating the stability of the machine except by using personal judgment. The Bureau of Mines responded to this problem by developing a front-end loader stability indicator whose primary function is to Indicate to the operator when the machine is approaching an unstable situation which may trigger a rollover. The device bases Its interpretation on measurement of the normal loads on the machine's wheels. Strain gage instrumentation located on the machine is used to monitor the magnitude and change of forces acting normal to the front-end loader's wheels. These forces are direct indicators of the machine's center of gravity relative to its position on the ground. The strain gages are connected to electronic circuitry which amplifies and processes the signals. Stability or instability of the loader is relayed to the operator through a display of green, amber and red lights.

Jan 1, 1986

Louisiana's coal reserves, located in the north-western part of the state, consist entirely of lignite, with estimated recoverable reserves of about a billion tons. Although lignite deposits were discovered in the early 1800s, the first documented use of lignite occurred at the federal arsenal near Shreveport during the Civil War. By the late 1800s, lignite use was common by blacksmiths, railroads, and steamboats. Lignite production ceased, however, from the early 1900s until 1985. A new lignite mine permitted September 1, 1985, produced 0.2 million tons in its first year. The operation uses a seven-mile-long conveyor to transport lignite to the associated mine-mouth power plant. The surface coal mining reclamation and enforcement program in Louisiana was approved October 10,1980. Louisiana's Abandoned Mine Reclamation Plan was approved December 10, 1986

Jan 1, 1992