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By D. E. Pollock, Andrew B. Cecala

It has long been known that ventilation is a cost-effective method to lower respirable dust concentrations in all types of mining applications. The National Institute for Occupational Safety and Health has been working on a number of different research techniques that use ventilation as a critical component to lower respirable dust levels at surface and metal/nonmetal operations in the United States. This article presents five such research efforts. The first research area discusses how improving the ventilation flow patterns in an iron ore mill facility lowered respirable dust concentrations by 31 pct throughout the primary grinding area. The second research area examines how respirable dust levels were lowered at a dimensional stone shop by using air cleaning units suspended from the ceiling. A third area discusses how improvements in ventilation at underground limestone mines lowered respirable dust concentrations. The fourth area examines how improvements in dust filtration and pressurization systems significantly impacted the air quality in enclosed cabs of surface mining equipment. The last area presents a newly developed clothes cleaning technique. This technique uses an air spray manifold to blow dust from a worker’s clothing in an enclosed booth, which confines the dust for capture and removal by a baghouse dust collector. These research areas represent an array of different control technologies to lower respirable dust concentrations. Ventilation is an integral part of these control technologies.

By Ronald P. Hollenbeck

Shales in the Appalachian Region of Kentucky and Tennessee were sampled and tested to determine their use as raw materials for the manufacture of lightweight aggregate by the rotary-kiln method. Nine samples were obtained from eastern Kentucky and 143 samples were obtained from eastern Tennessee. As a result of preliminary testing of these samples, two sources in eastern Kentucky and 11 sources in eastern Tennessee were resampled for rotary-kiln tests. The rotary-kiln tests showed the two sources in Kentucky and seven sources in Tennessee contained shale that would produce satisfactory aggregate. Lightweight aggregate processed from these nine sources was tested in concrete shapes and was found to be suitable for use in structural concrete.

Jan 1, 1968

By John W. Sweeney

The southeastern phosphate industry is investigated to determine its role in supplying the United States and world phosphate demand. The report shows that the southeastern (Florida, Tennessee, and North Carolina) phosphate industry is the leading domestic and world producer of phosphate rock, The report emphasizes size and organization, production capacity, transportation, and marketing of the southeastern phosphate product, Factors affecting the supply- demand relationship of the southeastern phosphate industry and world phosphate production-consumption relationships are analyzed and related to the southeastern phosphate industry. Past trends are projected and the future role of the southeastern phosphate industry is analyzed to determine its ability to supply the United States and rest-of-the-world phosphate requirements in 1985 and 2000. The projections show that southeastern resources are ample to supply domestic and export requirements at the projected rates of consumption well beyond the year 2000.

Jan 1, 1970

By S. H. Lorain

This paper is a preliminary report on recent lode gold mining activity, operating conditions, and mining and milling methods at properties in production in September 1936 in the gold belt of northeastern Oregon. A few inactive properties are described also. Districts, inactive in 1936, that have been important producers at some time in the past are mentioned briefly. This is one of a series of similar papers describing western mining districts. The past production record of the gold mines of northeastern Oregon entitles the region to be ranked as one of the important gold-mining regions of the United States. Although comparatively inactive for many years, lode mining in the region has recently undergone a marked revival.

Jan 1, 1938

By G. W. Jones

As part of its program for the promotion of safety, the Bureau of Mines has investigated various means of mitigating or eliminating the explosion hazards of combustible gases and vapors found in the mining and other industries. Knowledge as to the explosive characteristics of cyclopropane in air, oxygen, and other gaseous mixtures is of both theoretical and practical importance because cyclopropane is now used extensively in anesthesia. As such an agent it has many desirable characteristics, and increased consumption of this gas may be expected if the explosion hazards now attending its use can be minimized or eliminated. The present practice of using mixtures of approximately 20 percent cyclopropane and 80 percent oxygen should be discouraged because such mixtures are violently explosive and have led ,to fatal accidents.

Jan 1, 1940

By G. W. Jones

As part of its program for the promotion of safety, the Bureau of Mines has investigated various means of mitigating or eliminating the explosion hazards of combustible gases and vapors found in the mining and other industries. Knowledge as to the explosive characteristics of cyclopropane in air, oxygen, and other gaseous mixtures is of both theoretical and practical importance because cyclopropane is now used extensively in anesthesia. As such an agent it has many desirable characteristics, and increased consumption of this gas may be expected if the explosion hazards now attending its use can be minimized or eliminated. The present practice of using mixtures of approximately 20 percent cyclopropane and SO percent oxygen should be discouraged because such mixtures are violently explosive and have led to fatal accidents.

Jan 1, 1940

By Doris M. Hyde

There were no significant changes in the mineral industries of the smaller Caribbean Islands during 1980. Imported petroleum requirements continued to erode economic gains that may have occurred in other sectors. Some relief may be forthcoming as more qualified Caribbean countries take advantage of Trinidad and Tobago's petroleum product financing program (see Trinidad and Tobago). There were no crude oil discoveries in these areas during 1980, although some geophysical testing around the British Virgin Islands and Antigua war underway. In March 1980, the Government of Antigua sold a 75% interest in the 16,000-barrel- per-day West Indies Oil Co. refinery to the Swiss Intermaritime Bank and Intermaritime Management Services for $6 million. The new refinery company is called the National Petroleum Co. Shutdown since 1976, it was originally planned for the refinery to reopen in 1980, but refurbishing has proved to be more extensive than anticipated. The reopening is now expected in 1981.

Jan 1, 1982

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead "blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

By T. M. Barczak

A primary objective of the Bureau of Mines geomechanics research program is to develop a better understanding of support behavior and interaction of supports with the strata so that supports can be more closely engineered to the geological conditions in which they are employed. Four longwall shield supports were instrumented with an eight-transducer instrumentation array to measure leg, canopy capsule, and compression lemniscate link forces from which resultant shield loading was determined. The instrumented supports were monitored over a 4-month period, producing over 75 shield cycles of resultant shield loading. Resultant loading is the true measure of support resistance, providing both roof-to-floor and face-to-waste support reactions as well as the location of the reaction on the shield canopy. Observed roof support reactions were analyzed, with particular emphasis on horizontal shield loading, since it is the least understood design parameter. Average, peak, and change in shield loading during the mining cycle are discussed. Correlations among data parameters are examined, as is the distribution of support loading at the headgate and midface. Conclusions are drawn as to the effectiveness of the shield support at this installation. Recommendations are made for further research needs.

Jan 1, 1987

By James R. Aggson

This Bureau of Mines report describes floor heave ground control problems that have been encountered in a new underground coal mine in West Virginia. Previous experience in the coal seam, the results of physical property investigations, and in situ rock stress determinations are discussed. The apparent cause of the ground control problems is the existence of a high, biaxial, horizontal stress field coupled with a floor member that has time-dependent deformation characteristics, A theoretical analysis of the failure process is developed. The analysis is assisted by finite element techniques. Mine design recommendations based on this analysis are presented.

Jan 1, 1978

By F. W. Lee

This paper purposes to outline briefly results of seismic measurements made in the vicinity of blasts in a mine and in open-quarry operations. It endeavors to examine the amplitude and frequency of such vibrations as influenced by the loading, geology, and distance from the source and includes comments on factors that may index the destructiveness of a vibration and a method for measuring the stresses produced. There seems to be no simple mathematical analysis of the transmission of seismic energy through the ground, and experimental observations are at present most feasible. SEISMOLOGIC INSTRUMENTS Instruments developed by the Bureau of Mines for recording ground vibrations from quarry blasting comprise a new type of seismometer, oscillators, and a recording oscillograph. The seismometers respond to vibrations reaching them through the earth and transmit their characteristics by electric current to the oscillograph, where they are recorded by a beam of light on a moving strip of sensitized photographic paper. The seismometers are so constructed that their sensitivity to earth vibration can be controlled, thus keeping the amplitude of the recorded wave within bounds on the paper. Each instrument has been calibrated against vibrations of known intensity and frequency so that correction factors are known for the idiosyncracies of each unit. Moreover, each seismometer is calibrated in the field for its particular sensitivity setting at each blast. By these controls the actual movement of the earth due to vibrations of one ten-thousandth of an inch can be accurately measured.

Jan 1, 1936

By F. W. Lee

This paper purposes to outline briefly results of seismic measurements made in the vicinity of blasts in a mine and in open-quarry operations. It endeavors to examine the amplitude and frequency of such vibrations as influenced by the loading, geology, and distance from the source and includes comments on factors that may index the destructiveness of a vibration and a method for measuring the stresses produced. There seems to be no simple mathematical analysis of the transmission of seismic energy through the ground, and experimental observations are at present most feasible. SEISMOLOGIC INSTRUMENTS Instruments developed by the Bureau of Mines for recording ground vibrations from quarry blasting comprise a new type of seismometer, oscillators, and a recording oscillograph. The seismometers respond to vibrations reaching them through the earth and transmit their characteristics by electric current to the oscilloglaph, where they are recorded by a beam of light on a moving strip of sensitized photographic paper. The seismometers are so constructed that their sensitivity to earth vibration can be controlled, thus keeping the amplitude of the recorded wave within bounds on the paper. Each instrument has been calibrated against vibrations of known intensity and frequency so that correction factors are known for the idiosyncracies of each unit. Moreover, each seismometer is calibrated in the field for its particular sensitivity setting at each blast. By these controls the actual movement of the earth due to vibrations of one ten-thousandth of an inch can be accurately measured.

Jan 1, 1936

By C. R. Summers, J. N. Murphy

In response to the Coal Mine Health and Safety Act of 1969, mandatory noise standards have been developed that specify time-noise limits of mine personnel exposure. Most affected by elevated noise levels is the pneumatic roof bolter operator, both in terms of levels near or in excess of 115 dbA and in terms of length of exposure. Therefore, the principal emphasis of this Bureau of Mines report is on pneumatic drill noise control. It is not the intent of this report to suggest any drill redesign; instead, methods are suggested to reduce the noise level by complementing existing machines. An integral muffler system and a separate muffler system were tested in an attempt to lower pneurnaric drill noise levels. Pneumatic drills, when new, operate at about 115 dbA when drilling in sandstone. Using the drill muffler systems, it was possible to decrease the noise level of a 115 -dbA s rope drill to approximately 100 dbA.

Jan 1, 1974

By P. T. Brooks

Mineral nodules from the ocean floor represent a vast potential source of manganese, nickel, cobalt, and copper. Process development studies to devise methods for recovering these metals were conducted by the Bureau of Mines using two types of nodules--relatively low-grade calcareous nodules from the Atlantic Ocean and higher grade siliceous nodules from the Pacific Ocean. Ammoniacal carbonate leaching of reduced nodules appeared to have the best potential for processing the calcareous nodules, but the method proved to be impractical for recovering manganese. Extraction of 90 percent or better of the nickel, cobalt, and copper showed the technique to be attractive for recovery of these metals. The siliceous nodules appeared amenable to a process that starts with either a sulfur dioxide leach or a sulfation roast followed by a water leach to dissolve the soluble sulfates.

Jan 1, 1971

By Eleanor Abshire

[THE INCREASING use of hafnium as a vital component in atomic power reactors has brought this metal into recent prominence. A literature survey was made and this bibliography was compiled to provide research and production groups with a ready source of reference to this important metal anti its compounds. This service is rendered by the Zirconium Information Center, which is sponsored by the Department of the Navy, Bureau of Ships, and the F .S. Department of the Interior, Bureau of Mines, tit the Bureau's Northwest Electrodevelopment Experiment Station, Albany, Oreg. The following reference sources have been reviewed for this compilation : Chemical Abstracts; Industrial Arts Index; Crerar Metals Abstracts; Nuclear Sciences Abstracts; Bureau of Mine; Information Cicular 7771, Bibliography of Zirconium; anal Bureau of Mint' Information Circular 7830, Bibliography of Zirconium, suppllement to Information Circular 7771.]

Jan 1, 1960

By W. K. Overbey

The Bureau of Mines conducted surface joint and stress measurements, airborne remote sensing imagery studies, compass-oriented borehole televiewer surveys, numerical simulation of fractured wells, and well productivity studies in a four-quadrangle study area of Ohio, to determine the effects of earth fracture systems on the deliverability of gas storage fields. The results of these studies indicate that much useful information about a gas storage reservoir can be obtained and put to practical use by studying--(1) oriented cores for fractures and directional permeability, (2) orientation of induced hydraulic fractures for alignment of well patterns, and (3) aerial photos and multispectral scanner imagery for general surface geology comparison and to determine if some, development patterns can be generated by such results. The absence of known tectonic elements associated with flat-lying sediments, such as faults or fracture zones that can be seen on the surface, indicates that the use of remote sensors such as radar or aerial photography is not likely to be useful in picking well locations for drilling. Studies similar to those discussed here should be conducted in gently folded and strongly folded sedimentary formation areas to determine if the increased knowledge of earth fracture systems under these conditions might be beneficial in gasfield and gas storage reservoir development.

Jan 1, 1974

By M. O. Serbousek

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed an eight-piece precast reinforced concrete drift set for a small opening. Twenty-two sets of three different member sizes were tested to destruction under two loading conditions. A discussion of the test results and typical failure patterns is presented.

Jan 1, 1969

By H. E. Thomas

[The Bureau of Mines has conducted a field hydraulic fracturing experiment to determine the preferential orientation of induced fractures in oil shale at a depth of about 400 feet in the Green River Basin of Wyoming. The hydraulic fracturing treatment was performed by injecting extremely viscous water-base gel and 8- to 12-mesh sand into the oil shale through straddle packers set in an impermeable section of smooth-walled, 6-1/4-inch-diameter open hole. An impression packer proved that a horizontal fracture, which has an average width of about 1/2 inch at the borehole, was induced. A corehole drilled 100 feet from the fractured well intersected the fracture and confirmed its horizontal orientation. Because a horizontal fracture was successfully initi¬ated, it is inferred that the creation of multiple, closely spaced horizontal fractures may be feasible in Green River Basin oil shale.]

Jan 1, 1972

By H. F. Yancey

About 65 percent of the more than 400 million tons of coal produced annually in the United States is mechanically cleaned to remove the inorganic impurities before being sent to market. The impurities, principally shale and clay with some pyrite, average about 20 percent of the raw coal treated. Nearly 95 percent of the tonnage is treated by wet processes, in which water, suspensions of solids in water, or occasionally calcium chloride solutions are employed. Difference in density of coal and impurity is the basis of these processes. Of major importance in the separation is the competency of the impurities, that is, the resistance of the impurities to size disintegration in water. In general, the impurities are more resistant in geologically older coals or those in effect made older by metamorphism. If the impurities suffer reduction in particle size when immersed in water, the separation of organic from inorganic material becomes more difficult, Recently the Scientific Department of the National Goal Board (Great Britain) undertook fundamental research into the interaction of shale and water and also developed an empirical method of assessing shale breakdown or disintegration. 6

Jan 1, 1962