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By d&apos, D. V. Andrea

Nine rock properties were determined for rocks coming from 49 locations and having a wide range of compressive strengths. Plots of the nine rock properties versus each other were prepared. A stepwise multiple linear regression analysis was performed to obtain several equations for predicting compressive strength. Both linear and curvilinear relationships were assumed between compressive strength and the other rock properties. The prediction equations had multiple correlation coefficients ranging from 0.947 for an equation with 1 variable (point load tensile strength) to 0.986 for an equation with 25 variables. Of the properties tested only point load tensile strength could be used alone to estimate compressive strength with fair accuracy.

Jan 1, 1965

By A. B. Hooker, L. C. IlsLey

Explosives have been fired electrically for several decades. Mountains have been tunneled, deep shafts sunk, extensive coal and metal mine workings excavated and, in times of war, railroads, buildings, bridges, and fortifications have been destroyed by means of electrically fired explosives. Modern engineering depends so much on explosives that their safe and efficient handling and especially their detonation are of prime importance to all those connected with the use of explosive agents. Electric shot-firing is only one method of igniting explosives, but it is rapidly spreading and because of certain inherent safety features should be encouraged. Data collected by the Bureau of Mines indicate that in the United States a large percentage of the blasting in quarries, shafts,· and tunnels, and from 15 to 25 per cent of the blasts in mining operations, are set off electrically. The Bureau of Mines is interested in electric shot-firing because of its use in mining, and especially because electric methods, when properly applied, are undoubtedly safer than other methods commonly used. Electrical problems of many kinds must be solved in dealing with the various phases of electric shot-firing. Success in using an electric detonator is closely linked with the resistance of its bridge, the resistance of its leg wires, and the insulation of its current-carrying parts. The proper layout of a circuit where a number of shots are to be fired simultaneously depends not only on the types of detonators that are used and their arrangement and interconnections, but also on the size and insulation of the wire leading back to the source of power, and even on the source of power itself. Various types of electric shot-firing machines have been developed, and these offer still another field for study. In investigations of electric detonators and electric blasting equipment, the oscillograph is valuable because it can record electrical activity over very short intervals of time. By its use more complete information about electrical performance can be obtained than by any other means.

Jan 1, 1926

By Thomas O. Llewellyn

This U.S. Bureau of Mines (US8M) report presents a concise review on sources, processes, supply, and historical use patterns of domestic cadmium. It also covers a preliminary estimated cadmium material balance for the year 1989.

Jan 1, 1992

By Juel H. Stears

Research was done to determine if a hydraulically operated penetrometer developed by the Bureau of Mines could be used to estimate the roof-bolt anchorage capacity of mine roof rock. Tests were conducted both in the laboratory using cement cylinders and underground in shale rock. Hardness readings were measured by the penetrometer around the periphery of the bolt holes at the anchorage horizon. Roof bolts Nere then installed and subjected to an anchorage test. The results showed that the penetrometer readings could be used to determine the optimum stratum for roof-bolt anchorage but could not be used to make an accurate estimate of the anchorage capacity.

Jan 1, 1965

By Frederick W. Horton

The lack of comparable and accurate statistics of coal-mine accidents in the United States as a whole led the Bureau of Mines in 1911 to undertake the collection of such data. The importance of such statistics as a basis for remedial legislation can not be overestimated, moreover they serve to indicate the results of the efforts made by the Federal Government, State mining departments, and mine operators throughout the country to lessen the hazard of coal mining. The mining departments of the leading foreign coal-producing countries have long taken cognizance of the importance of such statistics. In Great Britain, official statistics of coal-mine accidents have been collected and published since 1851, in France since 1853, in Austria since 1875, in Germany since 1852, and in Belgium since 1831. The United States not only leads these countries in the production of coal but the output of its coal mines is greater than those of Great Britain, France, Belgium, Austria, India, Japan, and New South Wales combined. Accordingly, it is proper that there should be some official record of the accidents in this, the greatest mining industry not only in the United States but in the world. It is especially appropriate that this work should have been undertaken by the Bureau of Mines, as, through its investigations of mine accidents in the field, it is constantly in close touch with coalmining conditions throughout the country. Its engineers are not only able to obtain first-hand information as to a great many accidents, but, through their special training and experience, are able to appreciate the significance of the figures reported by the coal-mine operators, thus aiding an intelligent and uniform classification 01 the accidents for the country as a whole. Further, the State mining dnpartments and State mine inspectors of every State in the country having a system of coal-mine inspection are cooperating with the bureau by sending it monthly reports of accidents in the coal mines of their respective States. The receipt of such reports places the bureau in a most advantageous position to publish promptly statistics of these accidents. Although a few years ago accurate statistics of c~al-mine accidents in the United States as a whole were entirely lacking this bureau was able to pubjiish the 1912 statistics within three n:onths after the close of the year and long before corresponding statistics had been issued by the mining departments of the leading foreign coal-producing countries. The cooperative agreement with the State coal-mine inspectors has not only made possible the prompt publication of the statistics, but it has also enabled the bureau to classify the fatalities by months and according to cause, showing the months in which the greatest and the least number of men were killed and from what causessomething that has never before been accomplished for this country.

Jan 1, 1913

By W. J. Fene, J. J. Forbes

Through education, investigations, and studies and an expanded coal- mino inspection program the Bureau continued to dischargo the responsibility placed on it by Congress 39 years ago for promoting safety and health in the mineral industries. Although much still remains to be dono, definite progress was made in combating physical and psychological hazards in mines and plants. Accident-prevention cours os for coal-mine supervisory officials and special courses for coal-mine safety committeeman were inaugurated. First- aid, mine rescue, and other safety training was conducted for those engaged in all branches of the mineral industries. Assistance was given in recovery work after mine explosions and fires. Studies to reduce the danger of roof falls, the greatest single cause of fatal mine accidents, resulted in the development and adoption of new coal-mine roof-support techniques. Knowledge of the explosion and health hazards of mine and plant dusts and ways of pre-. venting them were advanced. Electrical equipment was tested for safety of operation in gassy coal mines, and emergency mine communications apparatus was developed and tested. More progress was made in the study of controlling flood waters that threaten life and property in the Pennsylvania anthracite region. More coal-mine inspections were made than in any previous year, and an impressive number of improvements resulted from the Federal inspectors' recommendations, even though many of them went unheeded. A program of con- trolling fires in inactive coal deposits on the public domain and private property was instituted during the year.

Apr 1, 1950

Water infiltration control techniques are designed to reduce the total volume of water entering an underground mine, and thus, reduce the volume of mine water discharge During the development of underground mines, water may be encountered in various quantities This water must be pumped from the mine during active mining, and in many situations, the weight of water removed will be more than the total weight of mineral extracted After abandonment of the mine, infiltrating water either floods the mine workings or discharges from the mine (27, 127) Infiltrating water may enter underground mines from above, below, or laterally through adjacent rock strata Earth fractures such as faults, joints, and roof fractures resulting from surface subsidence are commonly primary causes of water entrance Into abandoned underground mines Factors affecting the quantity of water entering a mine will be the depth of the mine, location of water bearing strata, and ground water flow patterns Investigations of the quantity of water entering underground coal mines have found the average rate of infiltration to range from approximately 6,262 to 10,280 liters per hectare per day (670 to 1,100 gal/acre/day) (27) Water flowing through underground mines flushes pollutants from the mine and may result in their discharge to the environment A reduction in the amount of flow usually results in a reduction in total pollution load discharging from the mine The techniques discussed in this section can be used to reduce the volume of surface and groundwater available to enter the mine system and transport pollutants The selection of a control technique will depend upon the characteristics of the mine system and the expected cost effectiveness of the technique In order for water infiltration control to be effective in controlling mine drainage pollution, the reduction in mine water flow must not be accompanied by an increase in concentration of pollutants (127) REFERENCES 2, 27, 51, 58, 127, 132

Jan 1, 1975

By C. O. Anderson, W. M. Meyers

Since 1922, when a brief report3 on the production and utilization of garnet was issued by the Bureau of Mines, there have been a number of interest—in developments in the technology of that mineral. Greater activity has been displayed in mining, new mills have been erected, and more attention has been paid to improvements in milling so that a more efficient and economical recovery of garnet has been possible. These activities have resulted in larger production; therefore, attempts are being made to broaden the market for garnet abrasives, and to find new uses for the unusual combination of physical properties than this mineral possesses. The writers have recently completed a field study of the occurrence, methods of mining and milling of garnet, and the manufacture and utilization of abrasive garnet products. This preliminary report indicates the most important sources of garnet, the methods by which it is recovered, and the manner in which it is recovered, and the manner in which it is utilized.Chemical and Physical Properties.The term ""garnet"" is applied to a closely related group of minerals which crystallize in the caste forms and possess similar physical properties, although their chemical composition may exhibit greater variation. The chemical composition of the garnet group may be represented by the general formula 3R"" O.R""' 203.3S102, in which R represents the bivalent elements calcium, magnesium, in the manganese state and ferrous iron, R"" represents the trivalent elements, ferric iron, aluminum and chromium in the chromie state. An account of the amorphous substitution of the different bivalent and trivalent elements, specimens whose composition may be represented by a definite formula are rare, the composition of any given specimen generally exhibits treat complexity.

Jun 1, 1925

By A. W. Khair, M. Ahmad, Gehi. L. D.

"This paper presents an analysis of the effect of the dynamics of bit wear on dust generation. Two surveys have been conducted in order to assess the mechanism and type of bit wear and to evaluate the impact of bit wear on the productivity of the continuous miners. Used bits were collected from the underground coal mines and these used bits were utilized in laboratory coal cutting. The effect of bit wear on dust generation has been quantified and its impacted on dust generation and ventilation system has been exemplified.INTRODUCTION Research has reduced the prevalence of Coal Workers Pneumoconiosis from 15 to 5 percent according to NIOSH reports (Breslin 1982). However CWP still have not been eliminated as a hazard to mine workers. To prevent coal workers from having black lung MSHA has established a very strict standard for coal mine operations (2.0 mg/m3 with silica content equal to or less than 0.1 mg/m3,). There are numerous coal operations still experiencing great difficulty with meeting the 2mg/m3 dust standard. Among these are the longwall sections and continuous mining sections. In order to meet the rising demand of energy and coal, the number of longwall operations and continuous mining operations would have to be increased. Thus a long term research commitment is required to develop basic solutions that are more generic and greater benefit to the mining and mineral industry.In continuous-mining operations, the miners are exposed to the dust produced during the fragmentation of the coal from the face plus the dust produced during loading and transferring of the coal. The fragmentation process generates most of the respirable dust. The amount of dust generated during fragmentation depended on the coal properties, cutting parameters and cutting bit configuration. Bit wear changes bit configuration, therefore, it also affects dust generation. Bit wear can be defined as the removal of material from surface as a result of mechanical action. In soft coal mines bit wear may not be a serious problem but in hard coal seams bit wear is very significant. In addition, as the good coal seams are depleted, the operators are mining thin seams and the seams with rock partings. During cutting these seams operators are sometimes forced to cut roof and floor rock or rock partings which result in more rapid wear of bits."

Nov 1, 1995

By H. P. Hermance

The Ore Hill zinc-lead mine in Grafton County, N. H., was investigated by the Bureau of Mines from March to July 1943 and from August to October 1944. Fourteen holes with an aggregate bore of 4,899 feet were diamond-drilled, the old workings were unwatered and sampled to an inclined depth of 250 feet, and the tailings dumps were surveyed and sampled. The deposit at the Ore Hill mine comprises a bedding-plane vein of massive sphalerite and galena with subordinate chalcopyrite and pyrite in a series of interbedded metasedimentary and metavolcanic schists about one-quarter mile east of their contact with the intrusive Baker Pond gneiss. The property was first opened about 1850 and was active at times to 1914. Production records are not available, but the output is believed to have been considerable. In 1944, leasers recovered a marketable mica product from mica schist from the dumps and certain outcrops. This report describes the work performed in the Bureau's investigation and presents the data obtained.

Jan 1, 1948

By K. K. Kelley

The entropy values at 298.1° K. for the elements and inorganic compounds, on which sufficient data were available for calculation in 1931, were discussed in a previous publication (96).3 Since that time the specific beats at low' temperatures of many more inorganic substances have been determined, and considerable advances have been made in the realms of spectroscopy applicable to the determination of thermodynamic properties. Moreover, a critical study of the existing vapor-pressure data made by the author (98) furnishes entropy of vaporization results suitable for obtaining approximate values of the entropies of a number of gases from the entropies of the solids or liquids. Consequently, it appears worth while at the present time to supplement the former publication, giving the new values now obtainable and making such revision in the older values as the data warrant. The methods of calculating entropies were discussed in previous publications (96, 98) and will not be repeated here. ENTROPIES AT 298.1° K. FOR INORGANIC SUBSTANCES In the following pages, the same arrangement is followed as in the previous publication (96). All entropy values are expressed in 15° gram-calories per degree Kelvin per gram-formula mass of substance. The figures given for gases do not include the effect of nuclear spin, as is nearly universally customary at present. The estimates of accuracy in the case of the values obtained from heat-capacity data apply only to the existing measurements and to the necessary extrapolations as they are made. It is assumed usually that the substances are in such an energy condition at the lowest temperatures reached in the specific-heat measurements that the usual normal type of extrapolation may be made. No allowance is made for error in this assumption. The recent work on Gd2SO4. 8H2O and FeC13 illustrates the difficulties that may arise in obtaining the entropies of some paramagnetic substances. Also the data and calculations for such substances as CO, H20, and N20 show that the correct entropy is not obtained in all cases by indiscriminate application of the usual

Jan 1, 1936

By J. W. Paul

Withdrawing timber in coal mines is done for the purpose of inducing the roof to cave in the mined-out areas and thereby relieve stresses in the immediate roof material over the working places adjacent to the breakline of the roof, thus preventing the crushing of the ends of pillars and adding to the safety of those engaged in pillar extraction. A secondary purpose is the recovery of timber for further use either as prop-, crossbars, lagging, sprags or cap pieces. At some mines timber is withdrawn as a precaution against fire which may he of spontaneous origin, because wood always aids a fire of any origin. With some of the power-driven types of machines now in use a greater proportion of mine timber may be recovered, and in mines where pillars are left too narrow for their removal some of the timber in rooms might be salvaged for further use.

Jan 1, 1933

By H. B. Brunot, Ilsley. L. C., E. J. Gleim

"INTRODUCTION One of the various phases of the work by the U.S. Bureau of Mines, in its endeavors to minimize the hazards that attend coal mining, is the investigation of electrical motor-driven machinery. The object of this investigation is to foster the development of explosion-proof machines for use in gassy mines. This investigation is conducted under the provisions of Schedule 2C, which prescribes the inspection and tests made upon motors, controllers, and other electrical parts to determine their ability to withstand internal explosion without discharge of any flames. The method of conducting these inspections and tests is described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine-Type Electrical Equipment for Permissibility, published in 1929. Formal approval of a machine for use in gassy mines is not granted by the Bureau of Mines until the machine is found to comply with the requirements, including inspection and test. When it is approved it is entitled to classification as a ""permissible"" machine.The high regard in which machines approved by the U.S. Bureau of Mines are held by engineers of other countries is attested by the growing number of shipments of permissible equipment; to other nations, including Australia, Russia, Norway, Japan, and Manchuria."

Aug 1, 1936

By W. L. Crentz

Before Korea was partitioned along the 38th parallel following World War II, the coal fields of South Korea, with the possible exception of the Samchok area, were not considered important to the industrial needs or Japan or Korea. Much of the demand for electric power in South Korea was met by hydroelectric installations north of the 38th parallel. Following cessation of hostilities between Japan and the' Allied nations in 1945, hydroelectric power continued to flow into South Korea from the north until 1949, when the North Koreans severed the power lines into South Korea, thereby forcing that section of the country to depend almost entirely upon coal to generate electric power.

Jan 1, 1953

By H. F. Yancey

The Baum-type jig used so widely to clean bituminous coals has not been adopted for anthracite. If proved suitable for anthracite, its use might lower preparation costs in some plants. Cleaning trials on a Pennsylvania anthracite in a laboratory-size Baum-type jig were undertaken by the Bureau of Mines to provide indicative information that would be helpful in determining whether the cost of a full-scale installation would be justified. Clean coal surpassing standard anthracite specifications was obtained in all sizes from Stove through No. 5 Buckwheat. Recovery effi¬ciencies were acceptable down to 3/16-inch size, but there was excessive loss of coal in the finer sizes. Thus the fine refuse produced in a commercial plant might re¬quire retreatment. A comparative cleaning trial in a dense-medium pilot plant provided a recovery efficiency only l percent higher than obtained in jigging.

Jan 1, 1957

By K. J. Maggs

The U.S. Bureau of Mines has investigated the chemical vapor deposition of diamond films on tungsten substrates. The effects of deposition parameters on the adhesion of the films was determined. The films were produced using a hot filament chemical vapor deposition system. Parameters investigated were substrate temperature and methane concentration in the feed gas. Film quality, morphology, and composition were characterized by scanning electron microscopy and Raman spectroscopy. Adhesion testing was performed using an indentation technique, and the results were quantified by relating adhesion to interface fracture toughness. Diamond films with well-faceted crystalline morphology with grain size greater than 1 µm had poor adhesion properties regardless of substrate temperature or methane concentration. Diamond films with smooth morphologies consisting of rounded clusters of small (<0.2 µm) diamond crystallites and amorphous carbon phases displayed much higher adhesion, although the conditions that led to the growth of these films are not understood.

Jan 1, 2010

By James D. Brown

The Bureau of Mines has written a computer program in FORTRAN to facilitate the calculation of concentrations from X-ray intensities in electron probe microanalysis. Philibert&apos;s absorption and Castaing&apos;s secondary fluorescence corrections are used; no atomic number correction is included. Background and dead time corrections are applied to the data before calculating the relative intensities. Data from any type of electron probe microanalyzer can be used with the program.

Jan 1, 1965

By D. T. Randall

Several years ago investigations were begun by the United States Government to determine the most efficient methods of utilizing the coals of the United States. These investigations, which were continued along several different lines, are now being carried on by the Bureau of Mines, in accordance with the provisions of the act creating this bureau . . It was because of the need for more complete information concerning the conditions under which coal could be economically burned in boiler furnaces without objectionable smoke that tests were made at the Government fuel-testing plants at St. Louis, Mo., and Norfolk, Va. In addition to this experimental work a number of commercial plants in the larger cities were inspected to ascertain what were the best methods then in use for abating smoke. The results of these investigations were reported in Bulletins 334 and 373 of the United States Geological Survey. Because of the continued demand for the information contained in these bulletins, the original editions of which are exhausted, they are reprinted by the Bureau of Mines. The text of this bulletin, particularly the information relating to smoke ordinances, was revised in the latter part of 1910 and the early part of 1911 by S. B. Flagg, engineer, who has charge of the steaming tests being conducted by this bureau.

Jan 1, 1912

By Clarence A. Wright, JAMES T. NORTON, JAMES G. PARMELEE

The object of this paper is to give to mining companies and to all others who are interested some idea of the possibilities in the treatment, by differential flotation, of lead-zinc ores of the Coeur d'Alene region and other districts. The purpose of these investiga.. tions is not to evolve a differential flotation process that would replace present methods of gravity concentration but rather one that could be applied to the relatively fine material and slime produced in the mills and treated unsuc_pessfully by gravity methods or by flotation. It is expected, of course, that the products to be obtained by differential flotation would be of much better grade than those now produced by flotation in the Coeur d'Alene mills. In view of the fact that it has been difficult to obtain representative samples of flotation feed from the mills, owing to the necessity of shipping the material wet and free from oil or other foreign matter that might be deleterious to the differential separation of the sulphides, the writers have felt justified in running flotation tests with the mill feeds in order to ascertain whether a differential separation of the sulphides could be effected. However, two different lots of flotation feed were tested for differential flotation, and the results of tests of one of these are given in this report. It is hoped that it will be possible later to test out the flotation feed for differential flotation on a large scale in some of the mills. This paper covers part of the investigations carried on by the United States Bureau of Mines in cooperation with the Idaho Bureau of Mines, the University of Idaho, and certain mining companies of the Coeur d'Alene region. Although the results of the tests included in this report are not to be considered final, they indicate possibilities and may suggest others leading to a solution of the problem of separating lead and zinc sulphides by differential flotation in the treatment of certain ores.

Jan 1, 1921

By J. P. Coughlin

The U.S. Bureau of Mines has developed a monitoring system that acquires and analyzes data for use in determining the conditions that may precede mountain bumps in coal mines. Based on a UNIX workstation linked to an array of geophones in a working longwall operation, the system captures complete waveforms of microseismic events and simultaneously obtains continuous samples of the voltage levels of each geophone. Event rates and locations are calculated and displayed in real time on the UNIX workstation, which is situated in an underground instrumentation room. These results also are transmitted from the workstation to a display computer near the longwall face. The system runs continuously and has the capability to acquire, analyze, display, and archive microseismic (transient) data and single point data, such as closure and pressure changes, simultaneously.

Jan 1, 1993