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By Albert E. Long

This paper presents a description of the operational mechanics involved in block-caving a granodiorite-capped, limestone deposit. This method was used for 24 years at the Crestmore mine, near Riverside, Calif., which was operated by the Riverside Cement Co. as a source of raw material used to manufacture a portland cement. The Crestmore mine is the only place where a block-cave method has been used to mine a limestone deposit. Structurally, limestone is relatively strong, and it is not usually considered to be a substance amenable to mining by block caving. It is therefore a credit to the engineering department of the Crestmore mine that it developed a satisfactory, relatively efficient method of block-caving a structurally stable rock. In the discussion, covering the methods applied to produce about 7.9 million tons of limestone and granitic rock materials by block caving, particular emphasis has been placed on an assessment of (1) physical properties of the deposit, (2) ground pressure and support, (3) methods used to induce fragmentation and maintain cave action, (4) surface and subsurface subsidence, (5) secondary blasting of oversize, (6) production rate, (7) safety, and (8) the advantages and disadvantages of the cave method as applied to this specific limestone deposit.

Jan 1, 1958

By John B. Gayle

During studies of the various methods for determining and specifying the factors that indicate whether a particular coke is better or worse than other cokes for metallurgical uses, questions arose as to the precision of screen-analysis tests on coke. Although the usual index of precision, the standard deviation of the test result, gives a measure of the precision of these data, the experimental determination of the standard deviation for a particular set of conditions requires tests on a large number of duplicate samples. Because this procedure necessaily involves a great deal of labor, an equation for predicting standard deviations from theoretical considerations has been developed. Results predicted with this equation agree satisfactorily with the experimental values and are applicable to tests on coal, coke, gravel, and other bulk materials.

Jan 1, 1952

By D. Harrington

Advocates of health and safety in mining have found themselves confronted in recent years with what might appear to be contradictory procedures with regard to dust occurrence in mines and what appear to be suitable methods or measures to give the mines and mine workers a maximum measure of protection against dust. A concerted and relatively effective drive has been made to introduce rock dust into bituminous and lignitic coal mines to prevent or limit explosion and fire disasters, while an equally determined effort has been and is now being made to curb rock dust or to eliminate it from air in metal mines to prevent or at least limit the occurrence of miners' consumption and other diseases. Both procedures are logical even though the efforts appear to be of an opposing nature. While rock dusting has not been applied in coal mines nearly as universally or as effectively as could and should be done, nevertheless a careful analysis of the record of the past 10 years indicates that the amount of rock dusting that has been done has resulted in the saving of a minimum? of 200 lives annually certainly no small achievement. Largely but by no means wholly due to the use of rock dusting, the number of fatalities from explosions and fires in our coal mines in the last 4 years haw been reduced more than 75 percent as compared with the 4-year period 1911-15, the first years of the existence of the United States Bureau of Mines, which was brought into existence in 1910 largely to try to do something about reducing the disgracefully high fatality occurrence from explosion disasters in our coal mines. Hence, rock dusting has been given at least a. trial and has proved its effectiveness definitely.

Jan 1, 1937

By Irving Hartman

The results of the first experimental study by the Bureau of Mines on the explosive properties of metal powders were published in 1945. Since that time the explosibility of numerous other industrial dusts and powders has been investigated. Part of this information has been published, but most of the data has not been released to date. This paper summarizes the results of experiments on 22 samples of titanium, zirconium, thorium, uranium, and hydrides of these metals. The major part of the investigation was made under cooperative agreement with the Atomic Energy Commission.

Jan 1, 1951

By Earl T. Hayes

[This work represent a continuation of the efforts of the Metallurgical Division of the Bureau of Mines to ascertain and apply knowledge of miner physics to processes metallurgy.]

Jan 1, 1941

By D. Harrington

Although the hysteria. with regard to silicosis end other occupational diseases seems largely to haws passed, and more careful sober consideration is being given this subject, it would be very poor policy for any employer to take the stand that the storm has blown over and that he can safely relax and revert to the status of 5, 10, or more years ago in such matters. The real fact is that occupational-disease compensation is nor in its infancy and can be expected to grow by leaps and bounds. At present, while 46 States of the Union3/ and the District of Columbia have compensation acts, only the following have some fern of occupational-disease legislation: California, Delaware, Connecticut, District of Columbia, Illinois, India a, Kentucky, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, North Dakota, Ohio, Pennsylvania, Rode Island, Washington, West Virginia, and Wisconsin. Silicosis appears to be compensable under those acts in California, Connecticut, District of Columbia, Illinois, Kentucky, Massachusetts, Missouri, New York, North Carolina, North Dakota, Ohio, Pennsylvania, West Virginia, and Wisconsin; possibly it may be interpreted as compensable in others. Occupational-disease legislation (largely relating to silicosis) has seen under consideration in some form relatively recently in Arkansas, California, Delaware, Idaho, Maryland, Kansas, Massachusetts, Michigan, Minnesota, Montana, Nebraska, New Jersey, Ohio, Pennsylvania, Tennessee, Utah, and. Washington at least. It will be surprising if comparatively broad or inclusive occupational-disease legislation will not be on the statute books of nearly every State in the Union within the next 5 years. With this situation confronting him, the far-sighted industrialist who has the best interests of his organization at heart will immediately begin to "put his house in order," if he has not already done so, by studying possible occupational-disease hazards to his employees; moreover, he will promptly apply all known remedial measures or will attempt to devise such measures if none of those already devised seem to apply to his establishment.

Jan 1, 1939

By M. R. Geer

The ever-increasing need to guard against stream pollution has intensified interest in the problems of handling and disposing of flotation tailing. Therefore, the Bureau of Mines investigated the possibility of using crushed washery refuse to adsorb the free water in thickened flotation tailings on a bench scale and then in a pilot plant because the conventional methods of disposing of coal flotation tailings--impounding them or filtering them so they are dry enough to be conveyed to the refuse dump--are sometimes either impractical because of space limitations or costly because of low filter capacity. Most of the refuse samples tested were of similar mineralogical composition and exhibited similar water retention capability. The amount of crushed refuse required to adsorb the water in a particular tailing was influenced greatly by the fineness of the solids in the tailing and hence the percentage of solids to which it could be thickened. The ratio of crushed refuse to tailing solids required to provide a mixture dry enough to be carried on an inclined conveyor belt varied from 2.4 to 6.4. Several chemical agents that were tested were very effective in turning the free water in tailings into a stable gel. Fly ash also was very effective in adsorbing water.

Jan 1, 1968

By H. P. Greenwald, H. C. Howarth

There was reported in Bureau of Mines Technical Paper 5754/ a series of tests to determine the compressibility and bearing strength of specimens prepared from blocks of potash salt obtained from a mine near Carlsbad , N. Mex . The events leading up to the investigation were sketched in a foreword by George S. Rice , then chief mining engineer of the Bureau ( retired September 30 , 1937 ) ; this foreword also gives a discussion of the possibility of increasing the ultimate total recovery of the potash salt by " second mining" of pillars or by use of a longwall system . In June 1936 , Rice and the senior author visited Carlsbad with H. I. Smith , chief of the mining division of the Geological Survey , to observe mining then in progress and to discuss with the management of one of the mines records of convergence of roof and floor which they were obtaining . It developed that serious thought was being given to the possibility of roof failure resulting from shear at the faces of pillars . There was envisioned the danger of such cracks extending upward to water - bearing strata . Obviously , the simple compression tests of the potash salt then being made would throw no light on this question , and tests of assemblies of potash and roof salts would have to be made . In this connection it is to be remembered that in the mine no sharp division exists between the potash salt being recovered and the nearly pure halite which forms the roof . The interlocked crystalline structure is continuous , and there is merely a very rapid decrease in the proportion of sylvite in a short distance vertically . Figure 2 of Technical Paper 575 shows that two samples near the top of the salt being mined contained , respectively , 51 and 65 percent potassium chloride . Contrasted with this is an analysis of the roof salt given on page 24 of that publication , which showed only 3.6 percent potassium chloride . As the data given in Technical Paper 575 show , the roof salt is much less plastic than the potash salt . The immediate roof may then be thought of as a more rigid stratum of indefinite extent resting on and continuous with yielding supports and loaded uniformly at the rate of 900 to 950 pounds per square inch . Just what thickness of the salt should be considered as immediate roof is uncertain .

Feb 1, 1938

By Thomas Fraser

WHEN the Bureau of Mines initiated the program of large-scale research and development in the field of synthetic liquid fuels authorized in the Synthetic Liquid Fuels Act of April 5, 1044, the Coal Preparation Section was assigned the task of obtaining data on the preparation characteristics of the coal in large reserves that might be adaptable to use in this new industry. It is natural that, as the rapidly developing general research program brought about new concepts of raw-material quality, preferred geographical location, and the like, the orientation of coal-preparation investigations should have undergone some change. The first major assignment was the sampling and testing of a series of typical American coals deemed to he suitable for hydrogenation based on early research work conducted by the Bureau of Mines. This first series of tests has been completed and is reported in this paper.

Jan 1, 1950

By Edward G. Cunney

[Track in underground bituminous coal mines was investigated and technology has taken from other industries in order to Main information on conditions that impair the safety and efficiency of the track and to develop guidelines ad useful information on the constriction, inspec¬tion and maintenance of mine track. Volume l contains information oil the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features such as gage, descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. As a research product, it 0005 nut repeat the summary or derivations. Volume 5, Inspection Handbook, summarizes recommended standards and procedures from Volume 2 and provides related information for read: refer¬ence by inspectors in tin mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.]

Jan 1, 1977

By Jack Wasserman, Don Wasserman, Logan Mullinix, Shekhar Khanal, Kelly Neal

This paper presents current finding on truck driver average exposure to acceleration for several different manufacturer’s cab-over trucks on a variety of roads in different countries. The predominant time, for this aspect of the study has been spent in the area around London, England and Warsaw, Poland. The ECE directive 2002/44/EC has provided specific guidelines for vehicle operators 8 hour average acceleration exposure. The primary considerations have been on truck design including the air-ride driver’s seat. The truck manufacturers have produced truck cabs that have some separate suspension from the truck frame. The truck seat manufacturers have been producing air-ride suspension seats for the cab. Both of these designs have had the objective of meeting the ECE directive and providing the vehicle drivers with some degrees of comfort. This paper will provide some information on the ability of the vehicles to operate on a variety of roads and meet the objectives. Method The primary method for evaluation of the driver’s exposure has been the use of a seat pad attached to the driver’s seat. Although this sensor system provides the critical information for the driver, an understanding of the reasons for the values requires additional measurements. The initial study in England used both driver and passenger seat pads, as shown in Figure 1, as well as triaxial accelerometers mounted on the base of the seat. The latest studies used significantly more transducers to better understand the relative rotations and translations on the truck frame, the cab, and the driver. [ ]

Jan 6, 2006

By J. W. Town

This report summarizes the results of laboratory investigations conducted by the Federal Bureau of Mines to obtain hydrometallurgical information on the dissolution of mercury sulfides from ores, flotation concentrates, and pure mercuric sulfides. Statistical methods were used to design the experiments and evaluate the resulting data. Studies demonstrated that cinnabar is readily soluble in sodium sulfide, partly soluble in potassium sulfide, and essentially insoluble in ammonium sulfide. Additions of sodium hydroxide or potassium hydroxide to sodium sulfide solutions increased mercury extraction slightly; when either was added to potassium sulfide or ammonium sulfide solutions, mercury extraction was equal to that of sodium sulfide. Tests at the Albany Metallurgy Research Center showed that sodium sulfide would completely dissolve chemically pure mercuric sulfide, more than 95 percent of the cinnabar in 5-percent mercury flotation concentrates, and 60 to 90 percent of the cinnabar in low-grade ores. The double-leach tests showed that potassium sulfide would dissolve over 90 percent of the arsenic in mercury-arsenic products and 1 to 10 percent of the mercury; then sodium sulfide-hydroxide solutions would dissolve 80 to 90 percent of the remaining mercury and 5 to 10 percent of the arsenic.

Jan 1, 1961

By A. Salmoni, E. K. Gillin, T. Eger, A. Cann, P. Vi, M. Hunt

Kittusamy (Kittusamy & Buchholz, 2004) state that there have been few studies conducted to assess exposure to whole-body vibration (WBV) in the construction industry. They suggest that there is very little reliable data from the construction industry that characterizes exposure levels to various hazards including WBV or the health outcomes from such exposure and that there is a need for more exposure data. In a recent exploratory study of heavy construction equipment Cann (Cann, Salmoni, Vi, & Eger, 2003) looked at vibration levels for 14 different types of construction equipment. Eight of the 14 pieces of equipment tested exposed operators to levels of WBV that exceeded the recommended limits for an 8-hour period when comparing the measured VDV to the ISO 2631-1 standards. The purpose of the present research was not only to test a larger number of scrapers but also to investigate scraper operator exposure to whole body vibration (WBV) separately for each task. Methods 33 scrapers were evaluated for WBV in a variety of residential and road construction projects. Testing equipment consisted of triaxial accelerometers that allowed vibration data collection in all three orthogonal axes, with the x-axis positioned to measure vibration in the anterior-posterior direction, the y-axis in the medial-lateral direction, and the z-axis in the vertical direction. Root mean square accelerations (aRMS), vibration dose value (VDV), crest factor, and maximum transient vibration values (MTVV) were derived from this software and exported to an Excel™ spreadsheet for later data analysis. Test sessions for each piece of equipment lasted for approximately 20 minutes until at least three work cycles had been completed. Tasks included: idling while waiting for a bulldozer to push the scraper through the scraping phase, scraping, traveling loaded with dirt, dumping and traveling empty. Results Task breakdown by time reveals 25% of the work cycle was spent traveling fully loaded with dirt, 19% dumping, 21% traveling unloaded, 17% idling and 18% scraping. Calculation of aRMS vector sums gave values of 2.55 m/s2 during loaded transport, 2.46 m/s2 during dumping, 2.31 m/s2 during unloaded travel, 0.55 m/s2 during idling and 1.46 m/s2 during scraping (see Table 1). The highest acceleration values recorded were found in the z-axis during fully loaded transport reaching an average aRMS over three work cycles of 2.55 m/s2.

Jan 6, 2006

By S. M. Runke

The pegmatite investigations at the Rapid City, S. Dak., Experiment Station during; the pact 3 years have been primarily a study of recovering beryl from nonlithium-bearing pegmatite rock by continuous-testing methods. Beryl concentrates containing 25 to 88 percent beryl were produced from rock that ranged in beryl content from 0.1 to 2.5 percent. The beryl recovery ranged upward from 70 percent but averaged better than 80 percent. Although promising results have been obtained with flotation methods for upgrading these concentrates to standard specifications, additional work is needed to improve and simplify the procedure. In addition, it was demonstrated that several potentially useful coproducts could also be recovered from pegmatite rock. The principal coproducts were mica, feldspar, and quartz. A heavy-mineral product also was made from pegmatites containing tin, tantalum, and columbium. The recovery if these minerals in products meeting the specifications of the commercial users has been reserved for future study. The investigations also included studies on extraction of beryllium from both high-grade beryl and flotation concentrates of medium beryllium content. The procedure investigated consisted of sintering beryl or beryl flotation concentrates with limestone, acid curing the resulting sinter with sulfuric acid to dissolve the beryllium, and water leaching to extract the beryllium. Over 90 percent of the beryllium was extracted by this procedure. Most of the optimum conditions and quantities of reagents were determined for dissolving the beryllium. As aluminum and iron also were taken into solution by the acid, further research is needed on methods of recovering high-grade beryllium salts from the solutions containing these elements.

Jan 1, 1957

By Frederick C. Trutt

A guide to the utilization and development of extensions and modifications to the APL Mine-electrical-system Load-flow Program is presented. These modifications include the development of algorithms to minimize computational operations within the iterative-solution techniques, as well as minimization of the number of required iterations. Extensions to the load-flow program include the development of algorithms for the calculation of balanced faults, simplified specification of fault parameters, optional inclusion of pre-fault currents, and an alternate-solution technique.

Jan 1, 1978

By H. H. Schrenk, F. E. Griffith

"The increase in tunneling operations that requires working under pressures greater than that of ordinary atmosphere has raised the question of the use and possible limitations of respiratory protective devices under such unusual conditions. As little, if any, information is available, there is need for a comprehensive study of this subject before specific recommendations can be made. In the absence of such data it seems desirable to make a few preliminary observations regarding the problems associated with wearing respiratory protective devices under increased air pressures.Two distinct problems must be considered--the mechanics of the apparatus used under such conditions and the physiological effects of increased pressures on wearers of respiratory apparatus. This report is confined to the use of oxygen breathing-apparatus and gas masks under pressure.ACKNOWLEDGMENTSThe data presented were obtained at the Queens Midtown Tunnel under construction at the east end of 42d Street, New York City, during a study of compressed-air illness conducted by the Bureau of Mines in cooperation with the United States Public Health. Service and the New York City Tunnel Authority.Grateful acknowledgment for cooperation and the use of facilities is made to Dr. R. R. Sayers and his associates, particularly Dr. J. W. Crosson (who acted as observer during the oxygen breathing apparatus tests), of the Division of Industrial Hyiene, National Institute of Health; to the Port of New York Authority, through Dr. Edward Levy; end to the contractors, through Doctor Emery."

Jan 1, 1940

By Roy C. Bartholomae, Jeffrey Shawn Peterson

1. INTRODUCTION In the early 1980s, the U.S. Department of the Interior’s Bureau of Mines Pittsburgh Research Center required that a large reverberation acoustic facility be constructed. This facility was designed to determine the sound power level emissions of mining equipment, especially continuous miners and jumbo drills. A contract for a conceptual design of a reverberation chamber was awarded to Wyle Laboratories of Huntsville, AL, which had extensive experience in the design, construction, and accreditation of acoustical reverberation chambers. The following standards were referenced as guidelines for the design of the chamber: ANSI S1.31-1980, “Precision Methods for the Determination of Sound Power Levels of Broadband Noise Sources in Reverberation Rooms” and ANSI S1.32-1980: “Precision Methods for the Determination of Sound Power Levels of Discrete-Frequency and Narrowband Noise Sources in Reverberation Rooms.” Specific requested criteria included that the room be large enough to accommodate typically large mining equipment and that there be adequate acoustical modal density in the frequency range of interest. It was also required that the room dimensions would support broadband acoustical measurements down to the 100 Hz third octave band. With the closing of the Bureau of Mines in 1996, this reverberation chamber lay dormant for a number of years. However, this facility is now part of the National Institute for Occupational Safety and Health’s (NIOSH’s) Pittsburgh Research Laboratory (PRL). One of NIOSH’s missions is to decrease noise induced hearing loss among the nation’s mineworkers. To this end, PRL researchers are refurbishing and instrumenting this reverberation chamber to facilitate assessment of the various engineering controls being developed to decrease the sound power level emissions of mining equipment. Early on, this work has sought to bring the chamber up to the level of ISO 3743-21 standard for engineering grade measurements for broad-band noise, with a longer range goal of improving the lab to meet the requirements of ISO 37412standard for broadband precision grade measurements. 2. DESIGN OF THE REVERBERATION CHAMBER The nominal room dimensions are 18.3 meters long by 10.3 meters wide with a height of 6.7 meters. The chamber volume is 1,286 cubic meters. These dimensions are important, as few reverberation facilities are large enough to test typically huge mining equipment. The floor is poured concrete with a sealer to make it acoustically reflective. The walls are built of hollow concrete block, 16 inches long x 8 inches high by 12inches thick. Each block has two hollow cores. The hollow block cores were completely filled with concrete with horizontal and vertical steel reinforcing bars 16 inches on center. This was done to supply a

By L. M. Demers, D. C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology that results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoidsJ have been implicated as important biochemical mediator5 of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dust could influence the production of proinflammatory mediators in the lung environment. Primary cultures of rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500 and 1100°C. Prostaglandin E1 (PGE;V, thromboxane Ai (T}(Ay, and leukotriene 84 (LTB; levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 production was markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE1 production. Exposure of AM to freshly fractured coal dust resulted in a significant increase in production by AM, while exposure to stale coal dust did not influence AM TXA1 production. Neither "fresh" nor "stale" coal dust had any effect on LTB4 production. In vitro exposure of AM to untreated silica resulted in a significant increase in TXA1 PGE.,, TXA; and LTB4 production compared with control. However, exposure of AM to silica calcined to 11oo•c resulted in eicosanoid levels that were not significantly different from control. These effects were still apparent 8 wk after calcination of the silica particles. Silica was a more potent activator of AM eicosanoid production than was coal, and amorphous fumed silica was a more potent activator of AM eicosanoid production than was crystalline silica. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production and therefore may be important in the pathophysiological consequences of occupational mineral dust inhalation.

Mar 1, 1992

By Ronald T. Mayerle

In-1992, the U.S. Bureau of Mines conducted a mineral investigation of the Anderson Mountain study area, including RARE II area 4-942, in Lemhi County, Idaho. The 7,340-ha study area lies within the Salmon National Forest about one kilometer north of the old mining town of Gibbonsville (pop.: 100). The eastern boundary of the study area is formed by the crest of the Bitterroot Range. The crest also serves as the continental Divide, and as the border between Idaho and Montana. The study area lies within the Gibbonsville Mining District, an important past producer of gold from lode and placer deposits. Since the 1870's, several hundred claims for both types have been located in the study area. Thirty-six current (1992) lode claims and two patented claim groups (one lode and one placer) are wholly or partially in the study area. No placer claims are current. In all, twenty-seven lode and five placer properties in and adjacent to the study area were investigated. Workings on the properties included 2 caved shafts; 36 caved adits; 8 open adits; 120 small pits, cuts, and trenches; and 4 large dozed cuts.

Jan 1, 1993

By L. B. Pankratz

Thermodynamic data on carbides, nitrides, and other selected substances were reviewed, evaluated, and compiled at the U.S. Bureau of Mines Albany Research Center. Values for Cp°, S°, H° - H°298, -(G° - H298)/T, ?Hf, ?Gf, and log Kf are given in tabular form. Cp°, H° - H°248, ?Hf°, and ?Gf° are also expressed algebraically.

Jan 1, 1994