Search Documents

By John B. Goodman

A LOW-TEMPERATURE carbonization assay test is described, and factual data derived from this test are presented. The test procedure outlined in this report incorporates a mild-steel retort of improved design, an accurately controlled method of heating, and a complete collection and condensation system for the solid, liquid, and gaseous products of carbonization. The test described establishes, under closely controlled conditions, the relationship of temperature to yields of products on carbonization. Noncoking or weakly coking coals and other carbonaceous material are particularly amenable to testing by the assay. Mass balances of 100 percent± 0.3 are obtainable by this test. It is believed that the efficiency of the test and the accuracy of the type data obtained have been materially increased.

Jan 1, 1953

Papers presented at a U.S. Bureau of Mines (USBM) technology transfer seminar describe the causes of violent material failure in U.S. mines, measurement techniques for monitoring events that result in violent failure, and mitigation techniques for controlling failure. Specific factors contributing to violent failure are identified on the basis of geotechnical monitoring in 16 U.S. hard-rock and coal mines and on statistical analyses of 172 coal bump events. New monitoring and analysis techniques developed as tools for assessing violent failure; geotomographic methods that provide new capabilities for the study of material failure and stress changes over large areas; and seismic methods for determining source locations, calculating energy release, and determining source mechanisms are described. Fair correlations have been established among seismic parameters, elastic stresses, face support load, and violent events. USBM studies have identified the advantages using both yielding and stable pillars for coal bump control. A computer program has been developed as an aid for selecting room-and-pillar layouts. The practical aspects of implementing a destressing program is outlined for coal mines, while the importance of mine orientation and timely support installation in controlling buckling-type failure is identified for hard-rock mines.

Jan 1, 1995

The coal-bearing strata of Oklahoma occur in the eastern part of the state over an area of 14,500 square miles, 20.7 percent of the state's total area. Commercially valuable deposits of bituminous coal cover about 8,000 square miles in seams ranging from ten inches to five feet thick. Estimated reserves in Oklahoma are 1.6 billion tons, representing 0.3 percent of U.S. coal reserves. The vast majority of coal mined in Oklahoma used in a single power plant within the state. Oklahoma gained primacy when its regulatory program was conditionally approved January 19, 1981. Authority for the state to administer the Abandoned Mine Land program was granted January21,1982. On April 30,1984, the Office of Surface Mining substituted direct federal enforcement of the inspection and enforcement portions of the Oklahoma program. This substituted enforcement was based upon a finding by OSM that Oklahoma had not operated the inspection and enforcement portions of its program effectively. As of January 1, 1986, Oklahoma inspection and enforcement authority was reinstated. Full program authority was granted to Oklahoma on January 14, 1986.

Jan 1, 1992

By G. S. Rice, H. P. Greenwald, H. C. Howarth

"Stoppings in coal mines serve, important and. vital functions, such as coursing the ventilating current, sealing off abandoned or dangerous workings, sealing fire areas, and separating mines at boundaries. Stoppings may hold back water, but normally that is not their function; their design is, or should be very different from that of a hydraulic dap which is designed to a definite load, often a very heavy one, from one direction over an indefinitely long period. Hence, a dam usually requires an arched structure to resist hydraulic pressure, and it must be massive to meet vertical stresses due to heavy ground pressure.Stoppings are designed primarily to resist a pressure applied laterally through air or gases. Their strength cannot be stated without specifying the direction of applied load. A stopping may be placed in stress by proof pressure subsequent to erection, through extraction of pillars in the vicinity which may act direct, or by squeezing the ribs or heaving the floor. These forces act more or less parallel to the faces of the stopping and may be very great but measures must be taken suitable to each case, and it is impossible to allow for these in general specifications other than to call for normally good construction. A stopping is principally designed to resist the action of forces at right angles to its face, such as the shocks of blasting, the pressure of gas from instantaneous violent out bursts such as have occurred in certain British Columbia coal mines, sudden compression of the air by great falls of roof in closed spaces, and at time pressures that accompany an explosion of either fire damp or coal dust or both. This paper deals with the tests of pressures of explosions only."

Sep 1, 1930

By E. Robert Ruhlman

["Phosphate rock" is a broad term applied to natural deposits of minerals valued chiefly for their phosphorus content. More specifically, phosphate rock may be defined as a natural rock containing one or more phosphate minerals, usually calcium phosphate, of sufficient purity and in sufficient quantity to permit its use directly, or after beneficiation, in the manufacture of phosphorus-bearing products. The grade or quality of phosphate rock is expressed either in terms of its phosphorus oxide (P20S) content or the equivalent in tricalcium phosphate (Ca3(P04)2). The trade name for tricalcium phosphate is bone phosphate of lime (B. P. L.).]

Jan 1, 1958

By Bernard Lewis

The ignition problem: for a layer of firedamp bordering on a cloud of detonation products is evidently considerably more complicated than in the usual laboratory ignition experiments, in which a well-defined volume of gas is heated and the occurrence of ignition is observed after an induction period. An atmosphere of firedamp exposed to the detonation of a high explosive is subjected to heating by shock-wave compression and thermal conduction and to intermixing at the interface of the firedamp atmosphere and the cloud of deto¬nation products. Although a reliable physical-chemical analysis of the problem is not yet possible, one may nevertheless form a general view of the role of compression waves and the processes of heat transfer and diffusion at the interface. Near the mouth of a shot hole, or near a freely suspended cartridge, the firedamp atmosphere attains very high temperatures by adiabatic compression, and it is certain that such temperatures are sufficient to initiate chemical reaction. The pressure wave pattern is reproducible from one test charge to another if the initial experimental conditions are held constant; on the other hand, experiments on firedamp ignition do not yield a reproducible threshold condition for ignition, but only an ignition probability. Thus, the induction periods are sufficiently long that there is time for the compressed', heated gas layers to undergo random changes that may quench or promote ignition. Therefore, the analysis of the ignition problem hinges primarily on the discovery of the random events that modify the chemical reaction in the activated gas layers.

Jan 1, 1948

By Henry P. Chandler

TONNAGE of natural abrasives sold or used in the United States in 1959 increased 12 percent. Artificial abrasives produced in the United States and Canada jumped 24 percent. Imports, exports, and reexports of abrasive materials also showed gains. Sales of grinding wheels were up 33 percent and coated abrasives 17 percent. FOREIGN TRADE Imports of abrasive materials totaled $91 million, an increase of nearly 51 percent over 1958. Chief commodities contributing to [ ]

Jan 1, 1960

By C. M. Dice

This paper is one of a series being published by the Bureau of Mines on milling methods and costs. It describes briefly the procedure followed in concentrating hübnerite or? at the Ima tungsten mine, Lemhi County, Idaho. In October 1911 the Ima mill was utilizing combined gravity-concentration, flotation, and magnetic-separation units for the recovery of a tungsten concentrate and a pyritic silver concentrate approximately 120 tons of ore averaging 0.5 percent W03 is treated daily. The concentrates produced average 66 to 67 percent WO3.

Jan 1, 1943

By N. Kumar Kittusamy

The purpose of this study was to assess the adequacy of the cab design and to determine the percentage of musculoskeletal symptoms among operators of mobile equipment used in mining and construction. A questionnaire was designed to assess demographics, work information, job history, and musculoskeletal symptoms in operators of heavy mobile equipment. Information concerning equipment included design of the seat/chair, levers, pedals, bothersome vibration, quality of ingress/egress from the equipment, proper preventative maintenance and repairs, and age of the equipment. The body regions that were evaluated included the neck, middle/upper back, low-back, shoulder/upper-arm, elbow/forearm, wrist/hand, hip, knee, and ankle/foot. Five hundred and eighty six operators completed the questionnaire. The results indicate that these workers are at risk for developing musculoskeletal disorders, and the need to quantify risk factors (i.e., whole-body vibration and static sitting postures).

Jan 6, 2006

By Zabetakis M. G.

This Bureau of Mines report presents a brief summary of the explosion trends in United States coal mines for the past 160 years. These trends show that in spite of the overall improvements in mine safety, the number of fatalities from ignitions of methane has actually increased in recent years. Suggestions are made of procedures that can be utilized to reverse this trend.

Jan 1, 1973

The coal-bearing regions of Colorado cover approximately 29,600 square miles, which is 28.4 percent of the state's total area. The most important coal-bearing regions are located in the north western and west-central parts of Colorado. Coal resources vary from lignite to anthracite. More than 70 percent are bituminous; 23 percent subbituminous; 5 percent lignite; and less than 1 percent anthracite. The state's coal reserves total about 17.2 billion tons, 3.5 percent of national reserves. Approximately 8.8 million acres of coal rights in the state are owned by the Federal Government; on about 72percent of this land, the Federal Government controls both the coal and the surface rights. It is estimated that approximately 4.2 billion tons of coal reserves are under federal ownership in Colorado. Permitted acreage of mines in Colorado ranges from 40 to 13,114 acres. Differences in elevation create many climatic zones in Colorado. Local annual precipitation can average less than eight inches in some areas in extreme western Colorado to more than 30 inches in certain mountainous areas. Generally, precipitation rates are low at most mine sites, making revegetation difficult. Colorado gained primacy when its regulatory program was conditionally approved December 15,1980. The Abandoned Mine Land Program was approved June 11, 1982.

Jan 1, 1992

By James R. Boyle

The value of Alabama's nonfuel mineral production in 1987 was $446.6 million, an increase over that of 1986 and the first increase in 3 years. Alabama was second in the Nation in production of bauxite and ferroalloys; third in bentonite, crushed dolomite, crushed marble, and fire clay; and fourth in masonry cement. Trends and Developments.-Employment in the minerals industry remained relatively low for the second year even though the overall unemployment rate dropped to 7.9% by December. Employment in mining and primary metals dropped about 10% and 2%, respectively.

Jan 1, 1989

By J. B. Vander Sande, L. C. Rainey, P. Bolsaitis, B. Dirsa

"The structure and composition of silica-rich particles recovered by lavage from the lungs of three active miners with different medical histories were studied using high-resolution electron microscopy and chemical microanalysis. The results arc compared to the similarly determined structure and composition of respirable-size mineral particles obtained from roof-bolter dust-box samples from two coal mines of widely different bulk quartz concentrations. The results show that the lungs of the miners contain silica-based particles with structures not found in the mine samples. Also, the particle structures and compositions found in the macrophages were different in each of the miners. The rau.lu suggest the possibility that intracellular processes may affect the susceptibility of individuals to silica-induced pneumoconiosis. The cytotoxic and fibrogenic potentials of mine dusts result from the activity of their individual components. Whether this effect is additive or even mass (i.e., dose) related is questionable and has been the subject of many investigations. Particle size and size distribution of various constituent minerals, the surface structure and properties of individual particles, and the self-cleaning capability of the lung (i.e., the capacity of the macrophage system) may, among other variables, affect the pathogenic changes induced by dusts lodged inside lungs. Extensive epidemiological investigations conducted on miners from different coalmining districts, where equivalent dust exposures have been shown to result in vastly different frequencies of lung disease incidence, also confirm this hypothesis (1) In a recent study, Ferrer et al. (2) used energy-dispersive X-ray analysis (EDXA) to investigate the inorganic element content in pleura and lung in reference, silica exposed non-pneumoconiosis, and silicotic populations. Constant depositions of silicon and calcium were detected in visceral pleura, parietal pleura, and lung of the refence group and in visceral pleura and lung of the exposed non-pneumoconiosis and silicotic groups. Comparison of the silicon content in pleura between silicotic and exposed non-pneumoconiosis subjects showed a nonsignificant probability of difference, whereas there were no differences with respect to the silicon content in lungs."

Dec 1, 1995

7133. Clewell, D. H. The Gravimeter. Prec. and Trans. Texas Acad. Science 1941, Austin, Tex., vol. 25, 1942, pp. 86-88. Static gravimeters, unastatized and. astatized, are considered to be the most practical for oil exploration. One gravimeter is described using a beam whose moment about a pivotal axis is elastically balanced. Magnetic or electric fields are deemed unsatisfactory for balancing gravitational force because they cannot easily be kept constant. The gravimeter described is capable of detecting a change in altitude of 3 inches and a change in latitude of about 150 feet. V. S.

Jan 1, 1944

By C. T. Anderson

In July 1947, the U. S. Bureau of Mines, in cooperation with the Air Materiel Command, started an investigation of zirconium alloys with the object of determining the suitability of such alloys for high-temperature applications. This report covers the preliminary study of about 25 zirconium-rich alloy systems with respect to preparation, fabrication, tensile properties, metallographic structures; constitution, and heat resistance. Obviously, each system could not be investigated thoroughly, and this publication can be regarded only as a first approach. The more promising individual alloy systems will be studied in greater detail and reported in subsequent publications. The study of zirconium alloys on such a scale has been made possible by the U.S. Bureau of Mines developments in the past 5 years On producing zirconium metal. This basic process is similar to that developed by Kroll for producing ductile titanium metal and consists essentially of reducing zirconium chloride by means of molten magnesium. The Northwest Electrodevelopment Laboratory at Albany, Oreg., has produced several thousand pounds of ductile metal in this manner and has a pilot plant producing over 300 pounds of metal per week. Alloys were prepared by melting Bureau of Mines zirconium and the best available grade of alloying element in graphite, with suitable provisions for preventing oxidation. The ingots were quartered longitudinally and sheath-swaged at 850° c. to 3/8-inch diameter rod. Two of those rods were send to Wright Field for room-temperature and 1,200° F. tensile properties. The remaining two sections were used for metallographic, hardness, heat-treatment, and heat-resistance studies. The salient features of this investigation are summarized in table 1.

Jan 1, 1950

By Howard J. Pincus

The purpose of the study is to investigate the effects of fracture fillings and associated alteration on the mechanical behavior of rocks. Experimental results are presented for 98 specimens from the Climax mine, which were tested since the annual report (May 1973). The conclusions reached are based on both these results and those reported in the annual report. The locations studied are the Climax and Henderson mines in Colorado and the San Manuel mine in Arizona. The rock types studied from each location are from: 1) Climax, medium-grained granite, fine-grained granite, granite porphyry, schist, and gneiss; 2) Henderson, rhyolite porphyry; 3) San Manuel, quartz monzonite and quartz monzonite porphyry. A description of the rocks was made including: color, texture, mineralogy, composition and fabric of fracture fillings, density, apparent porosity, and optical diffraction patterns. Unconfined and triaxial compression tests were run on the Climax and San Manuel specimens. Sonic velocities were measured during the compression tests; Shore sceleroscope hardness was measured before the compression tests. Conclusions are that some relation appears to exist between compressive strength and the following properties and features for all specimens: dynamic Young's modulus, sonic velocity, density, rock composition, slope of velocity curve, composition and fabric of fracture fillings-veinlets, and apparent porosity. There appears to be some relation between compressive strength and Shore scelerscope hardness for the quartz monzonite (San Manuel). A relation appears to exist between texture and compressive strength and the extent of failure on fracture fillings for schists, gneiss, and fine-grained granite (Climax). The amount of swelling clays (montmorillonite, hydromicas, etc.) present in the rock and the relative number of fractures in which they constitute of major portion of the fracture fillings are related to the strength of the rocks. Possible tests for checking the amount of these clays present is presented including saturation, dyes, and X-rays. A useful index relating to rock strength, as revealed in this study, is the presence of swelling clays in detectable abundances. These clays can be detected in the field with a simple wetting and striking test; in the laboratory they can be detected by X-ray and dye methods.

Jan 1, 1974

By Robert S. Schechter

A minitest, consisting of an injection/production well and at least two observation wells designed to detect the arrival of injected fluid leached minerals, and nonideal flow, is considered in this report. The test goals are to determine the susceptibility of the host formation to uranium leaching, kinetic parameters to scale the process, and to facilitate site restoration. This report considers permeability and mineral heterogeneities and other oxidant-competing minerals. To circumvent these nonidealities, which obscure the results, methods of interpretation have been proposed and tested by a computer simulator. In complex cases, clear-cut methods of interpretation were not found; but in every case the design of a test most susceptible to interpretation has been considered. The minitest is operationally simple and can be completed in a short time. With the correct design and interpretation it can return information to evaluate economics, ensure satisfactory leachate performance, scale to larger operations, and to identify restoration problems.

Jan 1, 1983

By P. L. Woolf

Three trials with oxygen-enriched unheated blast air are described. The trials were conducted in the Bureau of Mines experimental blast furnace located in Bruceton, PA. The first trial utilized moisture addition to the oxygenated blast. The second and third trial were conducted with natural gas injection. The test was basically a feasibility study and in that regard the practice was demonstrated to be feasible and also have possible advantages over hot blast operation. The testwork was conducted in 1964 and 1965 as part of a continuing study of iron making technology in cooperation with several North American Steel Companies.

Jan 1, 1985

By John C. Machisak

INJURY DATA and experience at coal mines in the United States for 1957 are presented in this bulletin under the following general sections: (A) General injury experience: Tables 1-6: Current data on number of fatal and nonfatal injuries, frequency and severity rates, and average severity. (B) Selected injury experience: Tables 7-36: Current data on causes of injuries, distribution of injuries by part of body injured, days of disability, extent of hand and machine loading, experience by employ¬ment and production groups, and various other operating factors and physical conditions related to the occurrence of injuries at the Nation's coal mines. (C) Injury experience, by States: Tables 37-41: Data on injuries, injury rates, employment, causes of injuries, and severity rates. (D) Major disasters: Table 42: Data on major disasters from 1948 to 1957. A major disaster is defined as a single accident in which, or as a result of which, five persons or more are killed instantly or die at any time thereafter. (E) Historical coal-mine-fatality experience: Tables 43-47: Data on fatalities and their causes at bituminous-coal, lignite, and anthracite mines from the earliest records through 1957.

Jan 1, 1960

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