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By Stephen Krickovic

A methane emission rate study was conducted in 1969 on a longwall section of a Lower Kittanning coalbed mine in central Pennsylvania. The longwall face was mined with a drum shearer between developed headings on the head end and headings on the tail end that were driven with a ripper-type continuous miner as needed. The study was conducted over 22 consecutive shifts (7-1/3 days). The average methane emission rate from the Lower Kittanning coalbed during mining at the face and developing the headings at the tail end of the face was 34 Am. Caving of the gassy overlying strata as the result of mining at the face increased the methane emission to rates ranging from 702 to 1,049 cfm.

Jan 1, 1971

By C. M. Frost

Crude shale oil produced by gas combustion retorting of Green River oil shale was hydrocracked over a cobalt molybdate catalyst at operating pressures of 500, 1,000, 1,500, and 3,000 psig, an operating temperature of 8900 F, and a liquid hourly space velocity of 1.0. Hydrogen feed rate was maintained at 6,000 scf/bbl. The volume-percent yields of total liquid product were directly proportional to the operating pressure. Weight-percent conversion and volume-percent yields of gasoline were directly proportional to the log of the operating pressure. Catalyst deposit percentages were inversely proportional to the log of the operating pressure. Nitrogen and sulfur removal rates as well as saturation of the liquid products increased as the operating pressure was increased.

Jan 1, 1973

Improve the dust control effectiveness of dry collection systems on surface coal mine drills. Approach Use a dust pelletizer to convert the respirable dust particles discharged by the dry collector into dust pellets that present no health hazard. Background Blasthole drills are well-known sources of respirable dust that can contain significant amounts of quartz. The drills frequently use a dry cyclone-filter type collector that can obtain dust reductions theoretically greater than 95 pct. However, surface mine drills using dry collectors typically have three major dust sources that significantly reduce the overall effectiveness of the collection system: (1) the dust collector dump cycle, (2) drill shroud leakage, and (3) leakage around the drill stem seal in the drill table.

Jan 1, 1989

By W. E. Miller, Kennedy. R. E., G. W. Jones

"INTRODUCTION Ethyl mercaptan (CH3,CH2SH), a combustible organic liquid of the thioalcohol type, is employed at an odorant in many types of fuel gases and dangerous atmospheres, which in themselves are devoid of characteristic odors, to give warring against leakage of such gases or atmospheres into places where they might constitute health or explosion hazards.Ethyl mercaptan has a penetrating disagreeable odor resembling that of onions, garlic, hydrogen sulfide, or rotting cabbage, that exceedingly low concentrations of it can be detected. The of odorants as a beans of detecting leakage of gases and atmospheres has been investigated extensively by chemists and engineers of the Bureau of Mines, and numerous reports as to its value have been published."

Jun 1, 1942

By James S. Browning

The Bureau of Mines conducted laboratory and small-scale continuous tests of kyanite ore from Georgia to determine the technical feasibility of recovering commercial-grade kyanite concentrates by flotation. The research indicated that combinations of sulfuric acid and petroleum sulfonate may be used effectively for flotation of kyanite from quartzite-kyanite ore. Over 87 percent of the kyanite was recovered in a concentrate analyzing 55.8 percent A1203 and 5.3 percent acid-soluble Fe203. Subsequent treatment of the flotation concentrate by high-intensity wet magnetic separation reduced the acid-soluble Fe203 to 0.8 percent and increased the alumina content to 57.6 percent, with a recovery of 82.7 percent of the total alumina in the ore.

Jan 1, 1970

By Garrett R. Hyde

Sintered yttria and sintered dysprosia can be used to make single-component thermistors having typical thermistor geometries and operable in the temperature range 500° to 1,200° C. However, at these temperatures, instability of platinum electrodes can contribute a slight aging effect if the thermistor is kept near 1,200° C for long periods. Typical characteristics at 500° C for an yttria disk thermistor 12 mm in diameter and 2 mm thick are a resistance of 12.4 megohms and a temperature coefficient of resistance of -3.8 percent per degree C. Typical characteristics at 500° C for a dysprosia thermistor of the same dimensions are a resistance of 1.84 kohms and a temperature coefficient of resistance of -1.6 percent per degree C.

Jan 1, 1970

By Charles Findlay, Stephen Krickovic

A methane emission rate study was conducted in 1969 on a longwall section of a Lower Kittanning coalbed mine in central Pennsylvania. The longwall face was mined with a drum shearer between developed headings on the head end and headings on the tail end that were driven with a ripper-type continuous miner as needed. The study was conducted over 22 consecutive shifts (7-1/3 days). The average methane emission rate from the Lower Kittanning coalbed during mining at the face and developing the headings at the tail end of the face was 34 cfm. Caving of the gassy overlying strata as the result of mining at the face increased the methane emission to rates ranging from 702 to 1,049 cfm.

Jan 1, 1971

By W. A. Heitbrink, M. Schmitz, J. A. Organiscak, A. B. Cecala, E. Ahrenholtz

Operator cabs on a front-end loader and a rotary rock drill were retrofitted with ceiling mounted heating1AC units and air filtration systems. Subsequently surface coal mine field studies were conducted to evaluate the respirable dust protection these retrofitted cab systems offer to the equipment operator. A significant 10: 1 respirable dust protection factor (ratio of outside to inside cab dust levels) was measured for the front-end loader cab with positive pressurization of the cab interior. Whereas an insignificant 3: 1 respirable dust protection factor was measured for the drill cab without positive pressurization of the cab interior. These results indicate that achieving positive interior cab pressurization with retrofitted cab filtration systems is a key element to their dust control effectiveness.

By Jr. Oitto

A polyester-type resin and deformed-steel reinforcing bars (rebars) were used in to strengthen and to stabilize bolted, fractured wall rock along pas 1:'y. in a western gold mine. Reinforcing bars were placed in boreholes drilled into fractured rock and then were surrounded by resin pumped under pressure into the holes and intersecting fractures until the wall rock was thoroughly impregnated. Pumping and injection equipment and infusion procedures are described. Visual examinations for movement in bonded and adjacent unbonded rock were made for 3 years. Fractured walls containing resin-rebar installations were strengthened. The results suggest that resin-rebar support can be used advantageously and economically in repairing fractured or broken rock when compared with rock bolting or timbering.

Jan 1, 1965

By M. L. Williams

In recent years the use of visual aids has expanded the? field of safety education. This is a modern adaptation of a method employed in ancient times, when simple paintings and drawings were the only means of recording current events. In its present application, visual aid employs sound and silent motion pictures, stripfilms, lantern slides, descriptive posters, and color. According to Roberts,3/ "Visual education is a method of imparting information which is based on the psychological principle that one has a better conception of the thing he sees than of the thing he reads about or hears discussed." Dent4/ further defines visual aid as "all the materials used to facilitate the understanding of' the written or spoken word."

Jan 1, 1951

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

Appendix B - Mine Evacuation Simulation Program - User's Manual B 1 Introduction Appendix B documents information necessary to use the emergency escape simulation program and to make modifications if necessary. For a user interested in using the program as it exists, Sections B 2, B 5 and B 6 are particularly useful. The program listing (B.6) can be used to prepare a card deck and the data cards can be punched from the directions given in Section B. 2. Typical input data and output printout summarized in B 5 provides guidelines for the program use. Sections B 3 (Program Nomenclature) and B 4 (Subroutine Description) describe, in detail, the inner workings of the program and are particularly useful for a user interested in modifying the program.

Jan 1, 1976

By R. B. Stroud

This report, part 3 of a series, describes and gives results of field. investigations by the Bureau of Mines on manganese resources of the Batesville district, Arkansas, from July 1956 through June 1961. The purpose of the Bureau's work was to evaluate the manganese potential of the district in fur- therance of the Government's program with respect to domestic resources of critical and strategic minerals. The work comprised areal reconnaissance, mapping, churn and core drilling, and sampling. In more recent years, the investigations were confined to manganiferous limestone, which constitutes a significant potential resource of manganiferous material. The resources of manganiferous material in the district are inferred to be on the order of 198 million long dry tons averaging between 4 and 5 percent manganese.

Jan 1, 1964

It is now widely accepted that horizontal stress is present nearly everywhere underground. Often it is more severe than the vertical stress. It is a major cause of roof control problems in underground mines. The AHSEM computer program contains two modules to improve mine layouts for control of horizontal stress. For development, the user specifies the orientations of the maximum horizontal stress, the entries, and the crosscuts. Angled crosscuts may be used, and the angles may be different for the right- and left-hand crosscuts. AHSEM then shows the user how the stress condition would vary as the entry and crosscut orientations are changed. The second module is for longwall mining. Severe stress concentrations can make headgate conditions hazardous when the entries are improperly oriented. AHSEM shows whether a particular longwall orientation and extraction sequence places the headgate corner in a stress concentration or in stress relief. It also estimates the magnitude of the stress concentration.

Apr 1, 2003

By Allen D. Look, Alan A. Sharp

"Churn drills for blast-hole drilling are important to the operation of most open-pit metal mines, but certain hazards are created through their use that cause fatal and nonfatal accidents.2/ The purpose of this circular is to present a code of safe practice prepared and followed at a large Arizona open-pit copper mine, where safety is recognized as a definite operating problem. Such a code, based upon a thorough study of available published information as well as practical experience gained from accidents and near accidents, is the result of considerable effort and monetary expenditure. It is hoped that other operations using churn drills may benefit by the code presented, either in comparison with existing rules or in the preparation of new operating instructions.The code presented is in use at the Morenci Branch of the Phelps Dodge Corn., Morenci, Ariz. Similar codes are used at the New Cornelia Branch, Ajo, Ariz., and in the waste-pit operation at the United Verde Branch, Jerome, Ariz.The authors gratefully acknowledge the cooperation of the Phelps Dodge Corp., whose personnel made: possible the collection of information included in this circular. Special acknowledgment is due Paul Simmons, safety engineer, and 3. U. Larsen, general drilling and blasting foreman, Morenci Branch, Morenci, Ariz.The importance of churn drills in Arizona mining is apparent when it is realized that at all the open-pit copper mines blast holes are drilled with this equipment. At Morenci, approximately 98 percent of the ground is broken by primary blasting of churn-drill holes.There has been a growing tendency in Arizona's copper-mining industry to change from underground to open-pit mining, with consequent increase in the use of churn-drill blast holes for primary blasting.3/Thirty-three churn drills are in use at Morenci for blast-hole drilling. The drills operate with 440-volt alternating current, and trailing drill cables, in 500-foot sections, connect with the portable drill transformer station.4/ Three Diesel-driven churn drills for drilling prospect holes also are in use. About 25 churn-drill shifts are operated currently on a three-shift basis. Ordinarily, a two-man crew is assigned to each drill; however, with prospect-drill crews a third man is added to handle the sampling.Benches are carried at a uniform height of 50 feet. Churn-drill holes are 9 or 12 inches in diameter and about 60 feet deep. The holes are 18 feet apart in hard waste and 21 feet in soft waste and ore, with toes from 11 to 13 yards at the shovel grade. Both the hole spacing and the toe have been increased gradually, until they are now 2 yards longer than in 1940. The average ground broken per hole is 3,500 tons, or 60 tons of ore per foot of hole drilled. The holes are drilled 10 feet below the bench to avoid leaving hard bottom, which requires secondary drilling and blasting.Starting with a 12-inch casing, the prospect holes average 1,200 to 1,500 feet in depth and terminate with 6-inch casing; the deepest hole drilled to date went to 1,735 feet.In addition, churn-drills are used at Morenci to drill blast holes in the silica pit, limestone quarry, and the tailings dam. Other irregular applications are the drilling of holes to set trolley roles and for concrete piling in building foundations."

Jan 1, 1950

By E. R. Maize, R. D. Currie

"Good ventilation is one of the first requisites in the safe and efficient operation of a coal mine. If a mine is gassy, the uninterrupted circulation of an adequate supply of fresh air is imperative if that mine is to operate with a relative degree of safety. That ventilation is not •only a safety consideration, but is an extremely important economic factor is shown by the fact that in many mines 50 per cent of the total power cost is for ventilation.The system used in the Graceton Coal & Coke Co. mine, Graceton, Pa., is believed to be unusual in many ways. Its application in this mine has re¬sulted in good ventilation of the working faces, no interruption to the venti¬lating current through the use of doors. a large- portion of the air circulated by the fan reaching the working places, low velocity air currents on traveling and haulage ways, low water gage and power consumption of the fan, and well-ventilated gob areas.This investigation was made possible through the courtesy of W. H. Robertson, mine superintendent. Fred Roberts, mining engineer, and Floyd Phillippi, mine foreman, assisted in the collection of information.The Graceton mine is a slope, opening the Upper Freeport or E bed, on the Pennsylvania Railroad about midway between Blairsville and Indiana at Graceton, Indiana County, Pa. The production is approximately 1,000 tons of coal per day and about 170 men are employed underground. The mine is considered gassy and was found to be liberating approximately 300,000 cubic feet of methane in 24 hours. The return airways terminate at a circular, concrete lined shaft 12 feet in diameter and about 115 feet deep at which is the exhaust fan.Mining is done by a block system with flat or level entries turned off the main slope at intervals of 1,350 feet, off which the butt headings are turned up the grade parallel to the slope. Rooms, which are about 225 feet long and 12 feet wide, are turned off the butt headings on 80-foot centers, leaving a block about 68 feet thick between rooms.Haulage on the main slope is by rope, with the hoist on the surface. This hoist is electrically driven through a 500-h.p., 2,300-volt motor. The rope used in this haulage is 1-1/8 inches in diameter. There are five electric trolley locomotives - one 10-ton and four 6-ton - which do all of the hauling in the flat and butt entries.Before it is blasted all of the solid coal and as much of the pillar coal as can be cut with safety is undercut by permissible mining machines. Shooting is done by shot firers who use permissible explosives, electric detonators, and dry-cell, nonpermissible batteries.In rooms where conditions are normal, timbering consists of two rows of posts on 4-foot centers. Posts are required to be within 6 feet of the face in machine-cut places and within 3 feet of the face in hand-mined places. Timbering on entries, where required, is of two types: a bar hitched into the ribs and supported by the coal, or 3-piece sets. The legs of the 3- piece sets used on the slope are set well back into the rib to prevent their being. knocked out by a wreck."

May 1, 1932

By Ivan F. Avery

PRODUCTION of carbon black decreased 4 percent in 1961. Output in the major producing States of Texas and Louisiana decreased 1 percent and 8 percent, respectively. Production of channel black continued downward, declining 10 percent in 1961 compared with 9 percent in 1960. Furnace black production also decreased 3 percent from 1960. Total domestic sales, however, increased 2 percent, Sales to most major consumers increased, but sales to the ink industry decreased 10 percent. Producer's stocks decreased 5,083,000 pounds during the year. Exports decreased 4 percent. SCOPE OF REPORT Carbon black is a very pure grade of quasi-graphitic carbon; particle diameters range from 50 to 5,000 angstrom units. Annual reports were submitted to the Bureau of Mines by operators of all commercial plants in the United States.

Jan 1, 1962

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals. Also, miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupational Research Agenda, problems created by occupational hearing loss include (1) the reduced quality of life due to social isolation and unrelenting tinnitus, (2) impaired communication with family members, the public, and coworkers,(3) a diminished ability to monitor the work environment (e.g., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers? compensation and hearing aids.

Jan 1, 2000

By D. E. Kirby

In the preparation of beryllium-copper alloys by fused-salt electrolysis, beryllium was electrowon from beryllium oxide dissolved in fluoride electrolytes and deposited on copper cathodes. At 880° to 1,030° C, deposition was on solid cathodes. Beryllium deposited on the copper, forming a liquid alloy that dripped from the cathode. Dripping alloys containing 3 to 4 weight-percent beryllium were produced with as high as 90 percent cathode current efficiency, by electrolysis at 910°.C. To prepare alloys of higher beryllium content, attempts were made at depositing beryllium on liquid copper cathodes. These efforts were generally unsuccessful, although alloys containing as much as 12 percent beryllium were prepared by this method. At temperatures of 1,100° to 1,300° C, requisite to maintaining beryllium-copper compositions as liquids, the beryllium reacted with cell structures.

Jan 1, 1972

By D. G. Kuehn

Studies were conducted by the Bureau of Mines to determine the positive ions and neutral species produced in glow discharges of gas streams containing 1.0 percent NO in helium, 29 percent dry air in helium, and 1.06 percent NO in N2, Mass spectrographic measurements were conducted for gas pressures from 2.3 to 10.0 torr and dc currents from 10 to 20 mAo Ion species observed included NO+, N2 +, O2 +, N+, and 0+ with lesser amounts of He+, He2+, and N02+. Variations in various ionic and neutral species with discharge duration were interpreted to be consistent with an electrically induced dissociation of NO to produce N2 and O2. No nitrogen oxides were observed to form in glow discharges of the helium-air mixture.

Jan 1, 1975

By C. H. Elder, Maurice Deul

Coal degasification boreholes drilled from the surface have been success - fully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment required, and design criteria for the treatment. Three examples of stimulation treatment show from fivefold to twentyfold increases in gas production. The tests were conducted in the Pocahontas No. 3coalbed, Buchanan County, Va., the Pittsburgh coalbed, Washington County, Pa., and the Mary Lee coalbed, Jefferson County, Ala. Two sites where the coal was hydraulically stimulated and exposed by subsequent mining show no adverse effect on mining operations through the treated zones. The induced vertical partings were confined to the coalbed and did not in any way affect either roof or floor rock.

Jan 1, 1975