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By Robert S. Dalzell

Following the introduction of roof shields to the U.S. longwall mining scene in 1975, the number of shield faces (faces supported by shields) has increased steadily, and the occurrence of accidents associated with ground control inadequacies at longwall operations has shown a downward trend. However, ground control problems in longwall mining still exist. New mining systems, however efficient, have run afoul of roof control. Shield faces have suffered extended stoppages because of roof cavities. In this report, the Bureau of Mines addresses the problem of longwall roof control. The report presents a review of foreign remedial and strata replacement techniques for longwall faces and evaluates their potential for domestic application. The technology reviewed includes meshing, chemical rock stabilization, cribbing, strain-absorbent modules, inflatables, synthetic foam, and monolithic fills.

Jan 1, 1985

By A. Aly Selim

This report describes the feasibility of predicting percussive drilling rates by equations derived from statistical regression analysis. The least squares statistical method was used and the analysis was performed both by direct and by stepwise linear regression analysis. The predicted penetration rate is a function of the drill power and the physical properties of the rocks penetrated. The results show promise that the technique may be of value in providing a mathematical model by which percussive drill manufacturers and users can predict the performance of a given drill. Experimental work involved two mining type percussive drills. Penetration data for these drills were determined from nine rocks drilled in the laboratory. Drill work rates (power) were determined in a separate series of experiments. Rock physical properties were measured from diamond-drill core samples taken from the same blocks used for percussive drilling.

Jan 1, 1970

By D. J. Parker

In attempting to discuss a subject of this character it should be clearly understood at the outset that the purpose is not to emphasize the mere fact of occurrence of such catastrophes, the memory of which time has largely relegated to oblivion, but rather to stress the means of their prevention, available not only subsequent to but also at the time of occurrence. A careful, conscientious, unbiased study of the causes of mine explosions leads inevitably and definitely to the conclusion that the human element is the most important factor. The human factor should however, be evaluated in terms of responsibility--responsibility on the part of the employer to recognize the existing hazards and take the necessary remedial action, and on the part of the employee to perform his duties faithfully, diligently, scrupulously, and in strict conformity with State mining laws and company rules or other regulations.

Jan 1, 1933

By Wilbert J. Huff, Raymond H. Moore

"Black powder is employed widely in peace and war. Its properties are therefore of considerable interest to many. The Bureau of Mines frequently is asked to furnish information on its use and safe handling in the mining and mineral industries in times of peace and is now engaged in studies of its application to the arts of war.Black powder has been the agent in many accidents - some very disastrous - and its handling and use are deemed very hazardous. The belief is widespread that the hazards are due principally to the ease with which the powder is ignited by a hot spark or flame in contradistinction to high explosives; these usually are ignited only with difficulty, and some burn incompl0tely and to a certain extent are self-extinguishing. Primary precautions, .therefore, should be taken to prevent the access of heat, spark, and flame.In black powder manufacturing operations a frequent source of disaster is the initiation of fires and explosions in the wheel mills in which the sulfur, charcoal, and nitrate are incorporated. Long experience has indicated that the wheel mill probably will fire if the powder is not kept moist enough; manufacturing supervision calls for the maintenance of a minimum moisture content, at least during the milling. Accidents occur elsewhere in the manufacturing line, and in an endeavor to minimize these, particularly those happening in corning mills, one of the writers suggested many years ago that a suitable humidity be maintained in other operations in the hope that it would serve protectively as in the wheel mill. The experience of one company for many years with this practice was favorable. It seemed desirable therefore, to explore the question experimentally."

Nov 1, 1944

By W. T. Benson

The Bureau of Mines has examined selected deposits of titanium minerals throughout the United States. The titaniferous magnetite deposits in the western San Gabriel Mountains, Los Angeles County, Calif., were among those selected for study, and in 1956-58 field work was conducted to determine the extent and character of the titaniferous magnetite deposits occurring in the area. This report describes this work and summarizes earlier work in the area by the Bureau and others. The titaniferous magnetite occurs disseminated as seams and lenticular pods in an anorthosite belt 4 to 6 miles wide that trends about. N. 80° W., extending from sec. 13, T. 3 N., R. 12 W., to the west boundary of R. 14 W., at which point the titaniferous magnetite-bearing rocks disappear beneath the sediments in the Santa Clara River Valley.

Jan 1, 1962

By Jr. Herty

Manufacturers and consumers of steel have come to realize during the past few years that cleanliness is of great importance in steels which must meet rigid specifications for various physical properties. Of equal importance is the consistent production of steel which is uniform in these properties. For maximum utility, steels should be uniform not only from heat to heat, but also from ingot to ingot and within each ingot. In the manufacture of killed steels such as the higher carbon forging grades, uniformity as indicated by the usual chemical analysis is easy to obtain, provided that a normal top discard is taken, as is always the case in steels poured with hot-top practice. No such uniformity, however, holds true for the nonmetallic matter, which consists for the most part of the products of deoxidation of the steel. For a large tonnage of steels which go into articles manufactured by deep-drawing processes, killed steel has never been successfully applied because with the present deoxidation practice, low-carbon killed steel is almost invariably extremely dirty. To obtain the desired qualities for deep drawing, the steel is rimmed, - that is to say, deoxidized with manganese and perhaps a small amount of aluminum, - the resultant product being of high purity in the skin of the ingot, but very badly segregated at the center of the ingot, particularly in the upper-central section. This segregation necessitates a very heavy top discard, and one of the major segregates is carbon which renders the steel too hard to draw properly. If clean, low-carbon killed steel could be made successfully, much better ingot yields would be obtained than by the present rimming steel practice. Furthermore, banded structures and outside and inside seams, which are undoubtedly due in a large measure to blowholes in the ingot, are defects which are very difficult to control in rimmed steel.

Jan 1, 1931

By Richard F. Zaffarano

The Bureau of Mines compiled information for the nonspecialist about natural gas liquids recovery from hydrocarbon streams in natural gas processing plants. Attention is directed to the impact of the technology of processing and the quality of gas processed in view of the increased availability of natural gas for processing. Significant changes in product and market trends within the natural gas processing industry are highlighted. Fixed capital-plant costs for grassroots, refrigerated-oil absorption and conventional adsorption schemes, adapted from published studies, are presented giving ranges of cost estimates for medium-sized plants. Marketed products of the natural gas processing industry are briefly discussed in relation to automotive air pollution problems and approaches to their control.

Jan 1, 1970

By E. S. Leaver

Experiments dealing with the dissolution of silver by cyanide from various silver minerals-were reported, several years ago.4/ This work showed that the silver in some silver minerals is completely and readily soluble in cyanide solution, whereas other silver minerals must be given special treatment before or during cyanidation to obtain much dissolution of the silver by cyanide. Flotation as a method for treating silver ores has not been studied much, except in the case of base-metal ores carrying silver, Particularly lead-silver ores. However, many mills now are concentrating gold ores by flotation, and when such ores also contain silver the recovery of the silver by flotation is of considerable importance. Moreover, many mines contain ore in which silver is the principal valuable constituent. Some of these ores are amenable to cyanidation, but the cost of a cyanide plant may be prohibitive because of limited ore bodies or other factors. In such instances the successful application of flotation would mean that the property could be operated.

Jan 1, 1939

By P. M. Gruzensky

Several experiments have been carried out in efforts to evaluate qualitatively a variety of electrolytes for refining bismuth. Most extensive work was done with the basic tartrate, hydrochloric acid, and hydrofluosilicic acid electrolytes. Deposits that are smooth and adherent can be obtained from these three electrolytes if low cathode current densities are employed. All three electrolytes were effective in purifying crude bismuth considerably, with additional purification indicated in each instance by a reelectrolysis step. With the basic tartrate electrolyte best results were obtained when the electrolyte was at 40° C, and contained at least 100 grams of bismuth per liter, An apparent disadvantage was depletion of bismuth from this electrolyte, causing the deposits to become spongy and nonadherent.

Jan 1, 1956

By Donald W. Ross

Petroleum oils of widely different grades have long been clarified or decolorized by contact with fuller's earths. More recently, so-called activated clays have also been used for this purpose. Still more recently ouch clays have been used in the form of nodules termed "catalytic pellets." Clays of varied appearance and from different localities possess the desired bleaching qualities, but evaluation of such clays, so useful to the oil industry, has not been simple. Previous methods of identification and evaluation have largely followed procedures of production methods and were not primarily based upon the fundamental properties of the clays. Thus) a false assumption has grown up that) bleaching clays probably have no common properties on which a-method of comparison can be based. Fuller's earths and activated clays have a large absorptive capacity for the color constituents of petroleum and its products decolorizing is accomplished by bringing the oil into intimate contact with the clay and later separating the decolorized oil from the clay with its load of absorbed coloring matter. Former practice in absorbing "color" was to use the clay as granules or In' powdered form. More recent practice is to use clay pellets that are more abrasion-resistant than the granules. The oil is either filtered through a bed of clay, percolation method, or agitated on contact with the clay, contact method. Viscous oils are decolorized at an elevated temperature, so that their viscosity is lowered to the point at which thorough contact with the clay is insured. Nonhumidifying, nonoxidizing gas, such as dry steam or dry nitrogen, is used to seal such hot oil masses from the atmosphere.

Jan 1, 1948

By Thomas M. Nasiatka

This report briefly describes the present state of the art and the technological highlights of tunneling from its inception to the present. The discussion is concerned primarily with tunnels driven through relatively competent rock for mine development and various civil purposes. In addition to pinpointing the major technological breakthroughs in tunneling, this report indicates their general effect on the speed of tunneling. The tunneling speeds are based upon data from approximately 80 tunnels listed in the appendix. These data include length; cross section shape and dimension; type of rock; tunneling method; method of breaking, loading, and transporting the rock; average linear progress rate; and cost in values during the period of construction. Most of the tunnels described have diameters of 15 to 30 feet.

Jan 1, 1968

By R. M. Gooding

This paper presents a short history of the production of mineral-energy fuels and energy from waterpower in the United States, with brief discussions of the utilization of each of the fuels and hydropower, and a look at fuels competition and interchangeability. Basic data, in figures and tables, are brought together in this publication for the production of coal in the United States from 1800 to 1960, for crude petroleum, natural gas liquids, and natural gas from 1859 to 1960, and for hydropower since 1900. Production for each segment of the fuels complex in the principal producing States from 1946 to 1960 is shown. Data are not included for consumption as such or for imports and exports.

Jan 1, 1963

By T. A. Henrie

One objective of Project Gnome is to study the feasibility of a phase of the Plowshare program recovering thermal energy from an underground nuclear explosion. The test will be conducted in an underground salt deposit. It is anticipated that some of the energy thus released will be stored as thermal energy in molten salt. This report describes the pre-Gnome experiments conducted at the Federal Bureau of Mines Metallurgy Research Laboratory, Boulder City, Nev. The objectives of this study were to determine the problems involved in the recovery of thermal energy from molten salts to assist in planning the experimental program for the Gnome project.

Jan 1, 1961

By R. V. Higgins

Tarner (1),3/ Muskat (2), and Schilthuis (1) have presented methods of calculating oil recovery by the expansion of dissolved gas with and without return of gas to the reservoir. Although electronic computers have eliminated the tedious and time-consuming calculations (4) required by each of these methods, many petroleum engineers do not have access to electronic computers. For these engineers a short method is presented that uses the Tarner method as a base. Moreover, for engineers who have access to computers and have not as yet prepared a program, the short Tamer method requires less computer time than the long iterative methods. In the proposed short method, no plotting of the calculated data is required to determine a point of intersection described in the original Tarner presentation, as only one calculation is needed to determine the value sought, or two calculations if greater accuracy is desired.

Jan 1, 1960

By A. C. Smith

The U.S. Bureau of Mines conducted a study to evaluate the effect of underground mining conditions on the activation of automatic sprinkler heads. Sprinklers were exposed to liquid fuel fires in a rectangular tunnel at airflows of 0, 45, 90, 150, and 250 m/min to determine the effect of ventilation and fire size on the time to activation. As the airflows were increased, the time to activate the sprinklers for a given fire size increased. Also, as the fire size increased, the activation time decreased. Temperature profiles of the tunnel showed that the maximum temperature near the roof was shifted downstream as the airflow increased. Experiments to determine the effect of rated activation temperature and response time index (RTI) value on activation time showed that the time to activate increased with increasing activation temperature, and decreased with decreasing RTI value. Exposure to the mine environment showed little effect on the activation times in large-scale experiments, and no significant effect in laboratory experiments. The results showed that airflow can have a significant effect on the activation times of automatic sprinklers. This needs to be considered in the design of effective sprinkler suppression systems for ventilated areas.

Jan 1, 2010

By H. C. Carpenter

Data are presented comparing results obtained with 17 different catalysts in hydrogenating crude shale oil to gasoline in single-pass operation. A method is described for predicting the maximum yield of gasoline obtainable at constant pressure for each catalyst from results of a limited number of experiments at different temperatures. Operating variables have considerable influence on yields and properties of products. With most of the catalysts, at operating temperatures below 890° F. liquid yield exceeded 100 volume-percent. Above this temperature the volume of liquid product decreased rapidly. Maximum gasoline production in most instances was achieved at a temperature higher than that at which the maximum volume of liquid product was produced.

Jan 1, 1959

By K. Zipf, Z. T. Bieniawski

"An extensive mixed-mode fracture toughness testing programme was conducted on coal from three coal fields. A special mixed-mode testing fixture for coal and other geologic materials was developed together with reliable specimen preparation procedures. Dynamic modulus measurements made on each of the 116 fracture toughness specimens showed that these coals exhibit certain degrees of anisotropy. The fracture toughness testing programme systematically varied the loading rate, specimen orientation and fracture loading mode. Loading rate did not significantly effect the fracture toughness over the quasi-static range tested. Orientation did have a significant effect on measured fracture toughness. In the coals tested, the divider orientation and arrester orientation had higher fracture toughness than the short transverse orientation. Data showed that one orientation could have almost twice the fracture toughness as another. The fracture toughness testing enabled certain evaluations of three mixed-mode fracture theories: maximum tangential stress, maximum energy release rate and strain energy density theory. Due to the extreme heterogeneity of the coals tested, definitive conclusions regarding the best mixed-mode fracture theory are not possible; however, data do tend to support the strain energy density theory. INTRODUCTIONThe major aim of this research is to ·develop a fundamental understanding of how fine· fragments of coal (respirable dust) are generated during a fracture process. In a related paper [l], a hypothesis was presented for the mechanism of fine fragment formation during a generic coal material/cutting tool interaction. In this hypothesis, fine fragments are created during coal material/cutting tool interactions that are best described as general mixed-mode fracture processes. Data are required on the mixed-mode fracture behaviour of coal, the physical character of the newly-created fracture surfaces and the character of the inherent flaw structure of the coal material. Accordingly, a test programme was designed that provided some information in each of these areas. The testing effort seeks to measure critical fracture toughness under mixed-mode loadings as a material parameter characterizing in part the tendency of various coals to generate undesirable quantities of fines and respirable dust."

Jan 1, 1990

By William P. Diamond

This report presents results of a cooperative research project between the U.S. Bureau of Mines and BethEnergy Mines, Inc. Four coreholes (two before mining and two after mining) were drilled at a longwall mine operating in the Lower Kittanning Coalbed to obtain coal and rock samples from over-lying strata to determine their gas content at various times in the mining cycle. The results of those tests indicate that 91 pct of the gas removed from the overlying strata came from coalbeds. Material balance calculations were made to compare the volume of gas produced both from gob gas vent holes drilled on the panel and gas removed by the mine's ventilation system with the volume of gas removed from strata directly overlying the panel to a height of 275 ft. This analysis indicates that only 40 pct of the total gas produced from the panel actually came from the strata directly overlying the panel. The remaining volume of gas production probably migrated to the longwall gob from overlying, and perhaps underlying, strata immediately adjacent to the panel and perhaps from greater distances downdip because of the establishment of a long-term pressure gradient in the study area.

Jan 1, 2010

By G. W. Elger

This report describes pilot-plant studies and an economic evaluation of a process developed by the Federal Bureau of Mines, Albany Metallurgy Research Center, to produce synthetic rutile from a rock-type ilmenite concentrate. In this process, ilmenite blended with coke and lime is smelted in an electric arc furnace to separate most of the iron as salable pig iron and to form a titania-enriched slag of low iron content, which is treated with oxygen and titanium pyrophosphate. The titanium oxides are converted to crystalline rutile; the phosphate glass contains most of the associated impurities. The treated slag is ground and leached with sulfuric acid to liberate rutile crystals, which are concentrated by physical methods. In pilot testing conducted to obtain data for a cost estimation, a synthesized product containing about 88 wt-pct TiO2 and less than 2 pct FeO was extracted from a rock-type ilmenite concentrate containing about 45 wt-pct TiO2. The estimated fixed capital cost (on a mid-1975 basis) of a plant producing 500 tpd of synthetic rutile is $28,290,100. Based on 330 operating days per year, the estimated operating cost for this process is $351 per ton of synthetic rutile. The estimated selling price of synthetic rutile made from rock-type ilmenite is $344 per ton, based on a credit of $160 per ton of pig iron and a 20 pct interest rate of return on investment after taxes.

Jan 1, 1976

By Rexford D. Singer

The purpose of this study was to evaluate the current literature on the use of calcium chloride and ligninsulfonates as dust suppressants with respect to potential adverse effects on health or the environment. Calcium chloride poses little internal hazard to man and animals, but toxicity to vegetation in and around the area of application should be expected. The effects, however, should be considerably less than those observed from using calcium chloride as a road deicer. Except for trout, ligninsulfonates seem to pose little direct systemic toxicity problems in aquatic organisms, animals and man or any problem with local vegetation. Because of a greater volume of information on its use and effects, calcium chloride is recommended over ligninsulfonates.

Jan 1, 1982