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By Dennis Cox, Stephen P. Signer, Joanne Johnston

A method to assist in the evaluation and selection of roof bolts using in situ measurements of roof bolt loading has been developed by researchers of the Spokane Research Center, National Institute of Occupational Safety and Health. Both axial and bending forces are measured by strain gauges at many locations along the length of fully grouted bolts during various stages of mining. This information is then used to (1) predict bolt loading for variations in bolt spacing, grade, and diameter, (2) calculate the design changes necessary in zones where bending loads are high, and (3) determine if bolt length is adequate. Results from several case studies of full-column bolt loading in coal mine gate roads are used to illustrate the design method. This knowledge will give design engineers a tool for the selection of roof support systems that will improve underground safety by reducing roof bolt failures.

By F. J. Gallagher

The purpose of this circular is to present information on the construction and use of reinforced rubber-jacketed tubing and insulating air-line couplings in coal mines where Airdox is used for breaking coal in order to eliminate, insofar as possible, arcing at the face between Airdox tubing and the track or other face equipment.

Sep 1, 1949

By C. K. Rose

A hydraulic scaling rig was placed in operation at the Bureau of Mines oil-shale mine near Rifle, Colo., in 1953. The rig consists of a self-leveling platform mounted on a hydraulic-powered boom. The boom is mounted on the bed of a diesel truck. The equipment provides a movable work platform from which two men can work in safety and comfort while barring loose rock from the backs and walls of the rooms, pillars, and haulageways. INTRODUCTION As a part of its synthetic liquid fuels program the Bureau of Mines has developed a mine in the richer oil-shale beds of the Green River formation near Rifle, Colo. An important part of the work of the Oil-Shale Mining Branch is investigation of techniques for low-cost mining of oil shale on a commercial basis. It is evident that scaling loose rock from the high backs and walls of the mine represents a portion of the direct mining cost. This paper describes the development of a scaling rig for operation in the upper heading of the mine, which is 39 feet high.

Jan 1, 1954

By D. D. Bolstad

The Bureau of Mines has developed procedures for sampling the geometry of fractures in underground coal mines. Stratified cluster sampling and the unit area concept are applied to the collection of fracture orientation data. The use of unit area mapping, stratification, and site delineation is made to assure collection of representative data. The procedures developed here help to isolate sources of variability in the fracture patterns.

Jan 1, 1973

By H. Schultz

Urban refuse that was mechanically separated at the U S Bureau of Mines pilot plant in College Park, Md., was successfully evaluated for its fuel values using standard coal analysis methods. Analyses performed on refuse samples taken from five sample points included moisture, ash, sulfur, chlorine, and heating value. It was recommended that characterization of the combustible portion of urban refuse by standard coal analysis procedures should be widely adopted.

Jan 1, 1975

By C. H. Elder

An experimental degasification program using a vertical borehole and vacuum pump to drain gas from the gob area of a longwall panel was successful at Bethlehem Mines Corporation, Cambria Division, No. 33 coal mine. Sixty-one million cubic feet of methane has been exhausted during a 9-month period. Daily production time in the panel increased as a result of lower methane levels in the returns. Removal of large quantities of methane in this way and the exclusion of it from the ventilating system will provide reduced cost in mine ventilation and provide a safer environment for the mine.

May 1, 1969

By J. R. Wait, D. A. Hill

A survey of the literature on ELF and VLF atmospheric noise has been made. Most measurements have concentrated on the vertical electric field and the horizontal magnetic field rather than the vertical magnetic field which is of interest in transmission between horizontal loops. The limited vertical magnetic field data indicates that the vertical component is generally 10 to 20 dB below the horizontal component. Three laterally inhomogeneous earth models have been analyzed for conversion of horizontal to vertical magnetic field. The rough surface model examines surface effects, the inhomogeneous thin sheet model treats volume effects, and the buried cylinder model treats localized man-made effects. All three models predict the possibility of significant conversion from horizontal to vertical magnetic field. A thin sheet model has also been used to examine transmission from a buried magnetic dipole source. It is found that the pre- dicted fields more nearly model the measured data than does the homogeneous half-space model.

By C. M. Frost

Crude shale oil produced during in situ retorting by the Bureau of Mines at Rock Springs, Wyo., was refined by three schemes. In the first, the crude oil was fractionated to raw naphtha and 400° F+ residuum. The residuum was hydrogenated over cobalt molybdate catalyst at 815° F and 1,100 psig. The blended raw and 160°-400° F hydrogenated naphthas were hydrodenitrified and then catalytically reformed. The 400° F+ hydrogenated oil was catalytically cracked. In the second scheme, the crude was hydrogenated over nickel-tungsten catalyst at 800° F and 1,500 psig. The hydrogenated fractions were processed by methods used in the first scheme. The third scheme resembled the second but, prior to hydrogenation, the crude was "hydrostabilized" over cobalt molybdate at 500° F and 500 psig. Yields of reformate and cat-cracked gasoline as volume-percents of the crude, and research-method octane numbers (with 3 ml TEL) for the three methods were as follows: First method, 32 pet reformate, 90 octane; 19.5 pct cracked gasoline, 99.2 octane. Second method, 29 pet reformate, 81.1 octane; 21.3 pct cracked gasoline, 99.6 octane. Third method, 28.2 pet reformate, 86 octane; 28.7 pct cracked gasoline, 95.9 octane.

Jan 1, 1974

Improve the efficiency of stainless steel pickling (chemically cleaning) operations by providing the industry a quick and convenient method to estimate pickling solution behavior and to estimate recommended ranges of nitric and hydrofluoric acid concentrations for effective pickling of stainless steels. Background Iron, chromium, and nickel in stainless steels react with nitric and hydrofluoric acids during pickling. Ions of these dissolved metals complex or combine with the acid anions. When the total metal concentration reaches about, 50 grams per liter of pickling solution, the solution no longer serves its purpose and is considered spent. Knowledge of cation and anion species in these pickling solutions contributes an insight into pickling chemistry and allows estimates to be made of the most effective ranges of acid concentrations. The Bureau developed a computational model of the complex equilibrium chemistry occurring among iron, chromium, and nickel and the pickling solution. Total concentrations, in grams per liter, of nitrate, fluoride, iron, chromium, and nickel were used as input; output was 17 cation and anion molar concentrations. The model, in the form (if an equilibrium program on a mainframe computer, was used extensively to facilitate Bureau research by determining chemical complexes in numerous stainless steel pickling solutions. However, the program's availability to members of the stainless steel industry, its intended users, was limited because of lack of mainframe compatibility and the difficulty of program maintenance.

Jan 1, 1989

By Stuart R. Zimmerley, John Gross

"In the study of ball-mill grinding at the Intermountain Experiment Station of the United States Bureau of Mines at Salt Lake City, Utah, it was desirable to measure the work input to a ball mill at the mill itself so that consideration of motor efficiency and transmission losses would be eliminated.The device adopted is essentially that used by Prof. H. E. T. Haultain4 in measuring work input to rolls. The mechanism was changed only so as to adapt it to a ball mill.Figure 1 is a diagrammatic sketch of the apparatus.The pulley which rotates the mill is loose on the mill shaft and is equipped with ball bearings. This pulley is connected by means of three tangential springs to the driving plate, which is solid on the mill shaft. Power applied to the loose pulley is transmitted to the driving plate, and hence to the mill, by the three springs; the greater the resistance of the mill, the greater the spring extension. The extension of the springs is transmitted by the steel extension tape to the differential integrating meter.The integrating meter is operated by two friction wheels in contact with the integrator disk which revolves at a definite ratio of speed to that of the mill. The friction wheels are held in contact with the disk by the spring suspension of the integrator and are connected to a differential gear cage, the revolutions of which are recorded on a counter such as is used in gas meters. Due to the differential gears the c e is stationary when the two friction wheels revolve at the same speed in opposite directions; this condition exists when the integrator is centered on the disk and corresponds to no load or to a zero spring extension. As the lead is applied, the springs extend and move the integrator from the center or zero point, resulting in a difference of speed between the two friction wheels. Due to the revolution of the differential cage this change in. speed is transmitted to the counter. The integrator and extension tape system is kept taut by means of a light spring attached to the integrator, the spring having just enough tension to assure that the integrator returns to zero when the load becomes zero."

Feb 1, 1931

By Charles Vaught

This paper discusses the fact that US coal mining organisations are losing the knowledge they need in order to be able to respond to emergencies. The authors note that knowledge management provides a useful perspective from which to view the problem, but that the debate about what constitutes knowledge should be broadened to include a debate about what constitutes management. It is argued here that knowledge is actually shared knowing distributed across group members; that such knowledge can be managed by cultivating it; and that narrative is the medium through which this may be done. The paper then examines NIOSH research that has attempted to use such an alternative knowledge management approach to help potential mine emergency responders better deal with the predicaments they are likely to encounter on-site.

Jan 1, 2006

By M. D. Schlesinger

Mercury exists in coal in minute quantities, but the large tonnages of coal consumed could represent relatively large amounts of mercury entering the environment. Limits have now been placed on the emission of mercury, and it is important that reliable analytical methods be available to the chemist. The Bureau of Mines has evaluated analytical techniques used by a number of laboratories; most used vapor phase atomic absorption as the final detection method. Neutron activation was used by some of the laboratories. All of the methods described could be applied, but they require careful manipulation to prevent loss or mercury contamination. In the samples analyzed the mercury content ranged between 0.05±0.01 and 0.4l±0.06 part per million.

Jan 1, 1972

By B. J. Scheiner

Carbonaceous gold-bearing ores of the type that occur in north-central and northeastern Nevada were investigated by the Bureau of Mines as part of its Heavy Metals Program. Specific objectives were to identify the carbon and organic compounds that prevent adequate gold recovery from the ore by cyanidation and to develop an economical process that would overcome the detrimental effect of the carbonaceous constituents. Activated carbon and long-chain organic compounds containing sulfur and nitrogen were found in the ore. Part of the material consisted of stable gold organic complexes. A mild oxidation technique that allowed gold extraction as high as 96 percent by subsequent cyanidation was developed. A variety of oxidants was shown to be effective in improving gold recovery, including chlorine and sodium hypochlorite (NaOC1). An electrolytic oxidation process was developed that was particularly advantageous from an economic and effectiveness standpoint.

Jan 1, 1971

By John J. McClelland

The Bureau of Mines conducted a study of longwall plow operations to identify dust sources and existing control technology. Three longwalls employing either the high-speed overtaking or conventional method of mining were surveyed. Principal operating parameters and on-site dust control technology at the time of each survey are described. Short-term gravimetric and instantaneous sampling results are discussed in detail. The relationship between longwall dust levels and dust control technology was examined.

Jan 1, 1988

By Richard J. Mainiero, Marcia L. Harris

The New York State Department of Transportation recently commenced highway widening and drainage improvement projects in Clarence and Amherst, NY. Drainage improvements including the installation of storm sewer lines required excavation to a depth of 2.5 m (8.2 ft). In September 2002, NYSDOT stopped further blasting when 800 ppm CO was detected in the basement of a house near the blasting site. At the insistence of NYSDOT, the general contractor developed a new blast plan with the assistance of an environmental consultant. The plan provided for the installation of multi-gas monitors in buildings of special concern and/or with basements and residential type CO monitors in all other buildings within 100m (330 ft) of the blast. The multi-gas monitors would be remotely monitored. The plan provided action levels which would ensure public safety. The blast design was also modified to allow for better venting of CO. Blasts were limited to 20 ft lengths. The overburden was to be removed from the rock and blasting mats put in place to prevent flyrock. Approximately twenty feet of trench adjacent to the blast was left open to allow ground movement and gas release. The use of CO monitors was effective to alert occupants of a building to the presence of CO. The most effective appeared to be the residential type CO alarms with digital readouts. They were simple and easy to use and allowed the public to participate in the process. False alarms were repeatedly received with the more sophisticated instrumentation. Residential type CO monitors are preferable to warn people near blast sites. More sophisticated instrumentation should be avoided unless personnel are experienced in its use. A general overview of the blasting and monitoring is presented and discussed. The use and effectiveness of residential type CO monitors and multi-gas monitors are discussed.

By Seth C. Schaefer

The Bureau of Mines has determined the standard Gibbs energies (AGf°) of CoS1.035 (cobalt sulfide) and Ni2.515S2 (nickel sulfide) with high-temperature galvanic cells using stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, CoS1.035, CoO, S02(g, 1 atm)//Zr02//02(g, 0.0114 atm), Pt, with the overall cell reaction C0S1.035(c) + 1.535 02(g, 0.0114 atm) = CoO(c) + 1.035 S02(g)¬ These results, combined with the best available data for ?Gf° of CoO and S02 from the literature, give the standard Gibbs energy of formation of CoS1.035 for the reaction Co(c) + 0 5175 S2(g) = CoS1.035(c) ?Gf° = -38.890 + 18.87 x 10-3T ± 0.185 kcal/mole (866.0 - 1,104.9 K), where temperature (T) is expressed in kelvins. Similar measurements were obtained for the cell Pt, N12.515S2, NiO, S02(g, 1 atm)//Zr02//02(g, 0.0122 atm), Pt, with the overall cell reaction Ni2.515S2(c) + 3.2575 02(g, 0.0122 atm) = 2.515 NiO(c) + 2 S02(g). Combination of these results with data for ?Gfo of NiO and S02 from the literature yields the standard Gibbs energy of formation of Ni2.515S2 for the reaction 2.515 Ni(c) + S2(g) = Ni2.S1SS2(c) ?Gf° -65.377 + 24.67 x 10-3T ± 0.541 kcal/mole (968.6 -1,053.7 K).

Jan 1, 1981

By Spencer P. Hwell, Charles E. Munroe

"Among the surplus explosives left on band with the War Department was a quantity of that styled Trojan Grenade Powder, which was especially designed during the war for use as a bursting charge in grenades and for which naturally there would be very little military use in time of peace. With a view to its disposal through use in civil projects a quantity was sent to the Bureau of Minas explosives experiment station, where analysis showed that its characteristic explosive ingredient was nitrostarcn and that the powder bad the following composition:Trojan Grenade Powder appears as a dark gray granular substance, part of which is slightly pulverulent. The granules fairly hard. The explosive is not at all dusty, and has the consistency of granulated sugar.Nitrostarch is a substance produced by treating starch with nitric and sulphuric acids and in appearance it looks very little different from powdered starch. It resembles nitrocellulose and nitroglycerin in its constitution and explosive properties and has been longer known than either, it having been prepared by Braconnet in 1833. Nitrostarch explosives have in recent years been developed for industrial use in this country, they having been used to an extent in blasting in the Canal Zone, yet as this grenade powder was a special composition it seemed desirable that a complete series of tests should be run upon it. This was done, and the results are reported in the following table in comparison with those previously obtained in testing ammonia dynamite."

Jun 1, 1920

By Charles D. Martens

Raw non fuel minerals produced in the United States during 1981 had an estimated value of $25 billion, about the same as that of 1980. In terms of 1980 dollars. the value of minerals produced during 1981 was $23 billion.2 This chapter includes tables for 1980 that were not available for publication in the 1980 Minerals Yearbook, but does not include the corresponding tables for 1981. The underlying causes of the overall decline in U.S. nonfuel mine production during 1981 were varied, but the common factor was the worldwide recession. In some cases the decline was traced to foreign competition. For example, iron ore production was lower in part because of increased imports of steel products such as coiled steel sheet. Another problem experienced by the domestic mining industry was the continuing difficulty in attracting capital. This was due in part to the attractiveness of investments outside the mining industry, such as short-term, high-interest securities. Another reason was the importation of commodities from countries where overall costs were lower because of such factors as high ore grade, lower taxes, lower wages, government subsidies, and less stringent safety and environmental regulations.

Jan 1, 1982

In the interest of safety ii: coal mining, the Bureau of Mines recommends: That all active underground coal mines, whether working or idle, have one or more fans in continuous operation. The capacity and installation shall be such that the entire mine workings are adequately ventilated at all times. Main fairs shall be located on the surface in fireproof housing offset from the line of any mine opening. The housing shall be provided with ample pressure-relief doors or other devices easily opened by the force of an explosion. The installation shall permit prompt reversal of air flow. For mines that liberate gas, the fan shall have at least two independent sources of rower immediately applicable. Ventilation of underground workings in coal mines is needed whether or not explosive gas is present. Natural ventilation is unreliable and often uncontrollable. Main fans should be on the surface; if they are in the mine, fire or explosion may make access difficult or dangerous and render the installation inoperative.

Jan 1, 1939

By Donald J. Barnes

Gold was found in samples collected from Pleistocene and Holocene stream and terrace deposits. Approximately 15,000 cu yd (11,400 cu m) of small and discontinuous terrace and stream gravel deposits in the study area are composed of material derived from sedimentary and granitic rocks. The detritus is subangular to subrounded, and poorly sorted, ranging from boulder to sand size. Gold values in samples collected averaged 8.2 cents per cu yd (gold value of $500 per oz). Pan concentrates and rock chip samples collected from reported mineralized zones showed an absence of economic minerals. Stream placer deposits are uneconomic. No potential was observed for metallic or nonmetallic minerals in the La Panza study area. No potential exists for gas, oil, or coal resources.

Jan 1, 1981