Search Documents

By Robert L. de Beauchamp

The Bureau of Mines reviewed aluminum chloride technology to determine the problems associated with its preparation from minerals, and to ascertain the best areas for research to solve these problems. Commercial AlC13 production processes are described and the ?state of the art? for the preparation of AlC13 from aluminous materials is evaluated. Areas for further research are indicated.

Jan 1, 1969

By Jay F. Colinet

Respirable dust exposure has long been known to be a serious health threat to workers in many industries. In coal mining, overexposure to respirable coal mine dust can lead to coal workers? pneumoconiosis (CWP). CWP is a lung disease that can be disabling and fatal in its most severe form. In addition, miners can be exposed to high levels of respirable silica dust, which can cause silicosis, another disabling and/or fatal lung disease. Once contracted, there is no cure for CWP or silicosis. The goal, therefore, is to limit worker exposure to respirable dust to prevent development of these diseases. The passage of the Federal Coal Mine Health and Safety Act of 1969 established respirable dust exposure limits, dust sampling requirements for inspectors and mine operators, a voluntary x-ray surveillance program to identify CWP in underground coal miners, and a benefits program to provide compensation to affected workers and their families. The tremen­dous human and financial costs resulting from CWP and silicosis in the U.S. underground coal mine workforce are shown by the following statistics: ? During 1970?2004, CWP was a direct or contributing cause of 69,377 deaths of U.S. underground coal mine workers. ? During 1980?2005, over $39 billion in CWP benefits were paid to underground coal miners and their families. ? Recent x-ray surveillance data for 2000?2006 show an increase in CWP cases. Nearly 8% of examined underground coal miners with 25 or more years of experience were diagnosed with CWP. ? ?Continuous miner operator? is the most frequently listed occupation on death certificates that record silicosis as the cause of death.

Jan 1, 2010

By L. J. E. Hofer

This Bureau of Mines study, part of a broad program of research in air pollution related to minerals, was conducted to determine the nature and extent of the poisoning of catalysts when used to remove certain air pollutants from exhaust gases. The poisoning examined in this investigation occurs when leaded gasoline is used as a fuel for automotive engines. This research was conducted in cooperation with the Public Health Service. The smog in the Los Angeles area is attributed to the effect of radiant energy on the mixture of hydrocarbons and nitrogen oxides found in the atmosphere there. A large portion of the hydrocarbons is believed to originate in the exhaust gases of automobiles. To prevent the escape of these hydrocarbons into the atmosphere catalytic mufflers have been proposed. In principle, these are simple and nonmechanical, consisting of a vessel charged with a catalyst capable of destroying the exhaust hydrocarbons by catalyzing their oxidation. However, these catalysts are severely affected by the particulate matter, mainly in the form of lead sulfate (PbS04), lead oxysulfate (PbS04.Pb0), and Lead chlorobromide (Pb(Cl,Br)2), contained in the exhaust gas. Deposition of lead on the catalyst as PbS04, PbS04, PbS0, and Pb(Cl,Br)2 restricts catalytic activity. As a result,after 20,000 miles of operation the temperature necessary to achieve 50-percent conversion of isopentane in a mixture of 0.2 percent isopentane, 2 percent carbon monoxide and 4 percent oxygen, and the balance nitrogen at 10,000 hourly space velocity has risen from 400° C. to 500° C. even with a catalyst taken from the exit portion of the catalyst bed. The rest of the catalyst was more severely affected. Therefore, it would appear that operation for 20,000 miles is near the limit for a catalyst.

Jan 1, 1963

By B. W. Dunning

The Bureau of Mines investigated the concentration and distribution of precious metals in the various fractions produced from mechanical processing of obsolete military electronic scrap. Whole avionic units, printed circuit cards, and electrical connectors were processed and analyzed. Materials recovered included baghouse lights, wire bundles, mag-netics, and metal concentrates from eddy-current and high-tension sepa-ration. Higher value fractions were processed by a commercial toll refiner for recovery of gold and silver. Lower value fractions were analyzed by the Bureau. Three fractions, the lights, wire bundles, and metallics from high-tension separation, contained most of the precious metals. Depending on the type of scrap feed, these fractions represented 34 to 60 pct of the original sample weight. Collectively, they represented 68 to 97 pct and 75 to 98 pct of the contained gold and silver, respectively.

Jan 1, 1983

By Isaac A. Zlochower, Michael J. Sapko, Ronald S. Conti

The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 preevacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion. After a predetermined time, the sampling probe needle is retracted by a second high-pressure air pulse to its normal (quiescent) state, allowing the sampling tube to reseal. The onset and the duration of sampling are independently variable and controlled by a time-delay relay package. This technique enables the monitoring of pyrolysis-charring in coal particles and the generation and combustion of the pyrolysis vapors in both large- and small- scale explosions. The following results were obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Laboratory: (1) Gas sampling of the leading edge of the flame front shows the large concentration changes, characteristic of the flame front; (2) gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen; and (3) the particles collected in the flame zone show signs of extensive pyrolysis and charring.

Jan 1, 1988

By H. Winkelmann

The author, who himself has worked inn the field with various types of torsion balances, expresses in the article his experience with the recently marketed Haff-Torsion-Balance. The advantages of practical work with Haff?s s torsion balance as compared with other types are mentioned. In spite of low weight and corresponding small dimensions (Model M = 23.5 kg., Model Al = 11.5 kg.) the sensitiveness is not less than that in the largest instruments. It is at 1.10-9, which is proved by calculations. A comparison with the corresponding values of other types of torsion balances (Eötvös, Askania, Gepege) is given. The mechanical features of the instrument are briefly described, and the balance is illustrated by a, cross section of it. -- W. Ayvazoglou. DETERMINATION OF THE ELEMENTS OF THE MAGNETIC AND GRAVITATIONAL FIELDS INDUCED BY AN INFINITELY LONG HOMOGENEOUS CYLINDER By G. A. Gamburzeff Gerlands Beiträge zur Geophysik, Band 19, Heft 2/3 Leipzig, 1928, pp. 210-230. The present work is a. contribution to the quastion of the reason for the magnetic and gravitational anomalies in the government of Kursk (Russia).

Jan 1, 1929

By J. H. Maysilles

The Bureau of Mines is conducting research on various technologies to recover alumina from domestic resources for feedstock to existing aluminum smelting capacity as a means to reduce dependence on imported bauxite, which represents 93 pct of U.S. aluminum requirements. One of the more promising technologies being investigated is the hydrochloric acid leaching of kaolinitic clay. In the hydrochloric acid leaching technology, alumina is recovered from iron-free aluminum chloride leach liquor and separated from impurity elements by sparging the liquor with HC1 gas to crystallize aluminum chloride hexahydrate (ACH). A large-scale crystallizer with a 336-gallon usable volume was constructed and operated to obtain engineering and design data for potential scale up and to demonstrate the ability of the technology to produce specification grade alumina. Test campaigns involving about 1,400 hours of operation were completed. ACH meeting all chemical purity requirements could not be produced by a single crystallization, but was produced by recrystallizing the product from the calcined kaolin clay leach liquor. Product crystals with a size distribution of more than 80 pct plus 100 mesh and 65 pct plus 65 mesh were made at a rate of 10 pounds of ACH/(hr)(ft3). The zirconium tube heat exchanger used to maintain constant process temperature operated with an over-all heat transfer coefficient of 420 to 500 BTU/(hr)(ft2)(°F).

Jan 1, 1981

By O. C. Blade

Production of crude petroleum in the Middle East (southwestern Asia) and in South America has increased greatly during recent years and has become a significant factor in the world's production of crude oil. Crude oil from fields in the Middle East increased from 256,164,000 barrels in 1946 to 305,833,000 barrels in 1947 and 417,201,000 barrels in 1948. Production from South American fields increased from 446,417,000 barrels in 1946 to 518,652,000 barrels in 1947 and 574,837,000 barrels in 1948. Crude-oil production from Canadian fields increased from 7,726,876 barrels in 1947 to 12,370,875 barrels in 1948, most of the increase being attributable to two fields, Leduc and Redwater, both represented by analyses in this report. Present indications are that production of crude petroleum from all these regions will continue to increase.

Jan 1, 1950

By Christopher Mark

Roof bolt system design means the selection of the type, length, capacity, and pattern of bolts for a particular application. Despite research efforts dating back 50 years, no design methodology has found wide acceptance. This paper begins by identifying four mechanisms that roof bolts use to reinforce the ground. It argues that the reinforcement mechanism is determined by the roof geology and stress level, not by the type of bolt. Next, the attributes of roof bolts are discussed in the light of recent research, including anchorage mechanism, installed tension, length, capacity, timing of installation, and installation quality. Several significant areas of controversy are identified. Design methods from around the world are discussed, including those based on empirical research, numerical modeling, and roof monitoring. Finally, some simple guidelines for preliminary design of roof bolt systems are proposed based on statistical analysis of roof support performance at 37 U.S. mines.

Jan 10, 2000

By Henry E. Perlee

In a Bureau of Mines study two-dimensional mathematical equations were solved that describe the transient thermal response of a rock dust particle in a cloud of similar particles in a gas flame's preheat zone subject to a radiant field from the approaching flame. The description includes both radiant energy absorbed and emitted by the particle and thermal conduction inside the particle and into the surrounding gas environment moving relative to the particle. Two situations were studied; in one the radiant energy incident on the particle is converted to thermal energy at the particle surface, and in the other the radiant energy is converted to thermal energy uniformly over the volume of the particle. The result of the study showed that for a 10-µm-radius particle, a 200-mg 1-1 loading density, and a flame approach velocity of 30 m sec-1, the particle temperature rise was twice that previously calculated by Singer and Cook based on the model of Essenhigh and Csaba. It was further established that under the conditions examined a rock dust particle temperature never increases more than about 200 K before crossing the flame front.

Jan 1, 1976

By Laurence G. Britton

Accurate flammability and ignitability data for chemicals form the cornerstone of procedures used to assess the hazards associated with commercial chemical production and use. Since 1967 the ASTM E27 Committee on the Hazard Potential of Chemicals has issued numerous, widely used consensus standards dealing with diverse testing and predictive procedures used to obtain relevant chemical hazard properties. The decision to issue a standard rests solely with the membership, which consists of representatives from industry, testing laboratories, consulting firms, government, academia, and instrument suppliers. Consequently, the procedures are automatically relevant, timely, and widely applicable. The purpose of this paper is to highlight some of the widely used standards, complemented with hypothetical but relevant examples describing the testing strategy, interpretation, and application of the results. A further goal of this paper is to encourage participation in the consensus standards development process. The paper is published in two parts. The first part (in the preceding issue of Process Safety Progress) dealt with the E27 standards pertaining to thermodynamics, thermal stability, and chemical compatibility. The second part, published here, focuses on the flammability, ignitability, and explosibility of fuel and air mixtures. © 2005 American Institute of Chemical Engineers Process Saf Prog 24: 12?28, 2005

Jan 1, 2005

By R. Hogg, S. Chander

"An overview of various physical and interfacial characterization methods for use in mineral processing is presented in this paper. The availability of a large number of characterization techniques and commercial instruments requires that the reliability and limitation of each be carefully examined. The choice of a method may depend upon the manner in which the information is to be used, for example in development of new processes, plant and process design, plant control, problem solving, etc. IntroductionThe behavior of particulate systems, in mineral processing and other applications, is primarily affected by the physical characteristics (size, shape, surface area, pore structure) of the particles and the nature of the different solid-fluid interfaces present. Mineral processing operations in general are either designed to modify and/or control physical and interfacial properties (grinding, classification, agglomeration, etc.) or are strongly influenced by them (flotation, flocculation, solid/liquid separation, etc.). Characterization of physical and interfacial properties should be an integral part of the development of new processes, plant and process design, and routine plant operation.Our purpose in preparing this article has been to present an overview of the current status of characterization, to point out areas of weakness, and to discuss the reliability and limitations of the various techniques, procedures, and instrumentation available. For more detailed discussion of methods, etc., the reader is referred to standard references.Sampling particulate solids.Sampling is a critical factor in any procedure for characterizing particulate materials — the reliability of characterization data is ultimately limited by the extent to which the sample used was truly represen¬tative of the population from which it was taken.Sampling from particulate solids involves two basic problems: (1) the selection of a random', unbiased sample and (2) choice of the appropriate sample size.The problem of sample selection involves the design of a sample collection procedure that ensures that every kind of particle in the population has the proper chance of being included in the sample without bias. Specific procedures such as the well-known cone-and-quarter technique have been developed and are discussed at length in the literature on particle characterization (Allen, 1981: Herdan, 1960: Gy, 1982)."

Jan 1, 1989

This publication summarizes, for all interested parties, the research, development, and demonstration in-house projects programed by the Bureau of Mines for fiscal year 1981 (October 1, 1980 - September 30, 1981) under its Minerals Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advances toward the Bureau's overall goal of providing the system technology required to create a healthier and safer working environment for the Nation's mining and minerals processing workers.

Jan 1, 1981

By W. D. Mcmillan

During the fall of 1943 the Bureau of Mines put down four churn-drill holes totaling 435 feet of bore at the McGregor zinc lead mine near Potosi, Washington County, Mo., after the property had been examined by John Soule, an engineer of the Bureau, in the fall of 1942. A small production of lead and barite ore had been maintained at this property for many Years from shallow deposits in residual clays. A few shafts had penetrated the underlying dolomites and exposed a network of narrow fractures containing galena, sphalerite, barite, and marcasite. The drilling by the Bureau tested conditions at depths ranging from 80 to 130 feet. This report sets forth the data resulting from the work.

Jan 1, 1948

By R. V. Higgins

A numerical method is presented to calculate the isopressure (isobar) lines and streamlines for an oilfield from the pressure distribution. A knowledge of these lines is useful in the study of the flow of fluids in underground reservoirs, especially for those containing gaseous and/or liquid hydrocarbons. This work was done primarily to enable determination of the shape factors needed in the calculation of petroleum reservoir performance. However, it has application for the flow of water in aquifers, or electricity or heat in odd-shaped geometry. Techniques previously developed were used to calculate the pressure distribution. From this pressure distribution, the isopressure lines were calculated accurately by the method presented in this paper. Then by successively projecting orthogonal lines from one isopressure line to another, the streamlines are determined. From the coordinates of the isopressures and the streamlines, the shape factors can then be determined by a published method. Computer methods are presented to calculate the streamlines and isopressures for any well-spacing pattern existing within a field with multiple wells. The method reproduces the flow net for several well configurations having extensive geometrical variations. Such information provides the petroleum engineer with data from which he can compute oil recoveries for different patterns and thereby maximize the recovery of hydrocarbons from the reservoir.

Jan 1, 1972

1. A total of 14,413 mining operations reported employment to the Mine Safety and Health Administration (MSHA). Nearly half (48.9%) were sand and gravel operations, followed by stone (28.5%), coal (14.7%), nonmetal (5.7%), and metal mines (2.1%). 2. Mine operators reported 240,000 full-time equivalent workers1 (down 3.9% from 1999). Independent contractors reported 42,000 full-time equivalent workers working on mine property (up 8.6% from 1999). Coal operators accounted for 26.8% of reported employee hours, followed by stone operators (25.9%) and sand and gravel operators (12.1%). 3. Eighty-four (84) work-related mine fatalities occurred in 2000 compared to 90 the year before. •The mine fatality rate was 29.8 per 100,000 full-time equivalent workers compared to a fatality rate of4.6 per 100,000 employees for all private industry. •Thirty-one percent (31%) of the fatalities occurred in underground work areas, which account for only17% of total employment. •Although the largest number of fatalities (28) occurred among miners who work for coal operators, coal contractor employees had the highest fatality rate (61.1 per 100,000 full-time equivalent workers). 4.There were 10,839 nonfatal lost-time injuries reported to MSHA, occurring at a rate of 3.8 injuries per 100full-time equivalent workers, and resulting in a total of 417,918 lost workdays.2 •Among all employees,3 the highest injury rate occurred among coal operator employees (5.6 nonfatal injuries per 100 full-time equivalent workers). •The highest percentage (34.7%) of nonfatal lost-time injuries were due to handling materials (e.g., over-exertion in lifting, pulling, or pushing objects), which also accounted for the greatest percentage of lost workdays (29.3%). •Among the most frequently occurring injuries, the most severe (as measured by the median number of days lost) were associated with accidents involving falls of ground, the use of powered haulage, and slips or falls. •The most frequently reported part of the body injured was the back (22.9% of all injuries). Back injuries accounted for the highest percentage of lost workdays (21.6%). 5.Seven hundred sixty-seven (767) cases of occupational illness were reported to MSHA. •The most frequently reported illness was repetitive trauma, resulting in joint, tendon, or muscle inflammation or irritation (37.3%). •There were 155 (20.2%) illnesses reported as hearing loss. The majority (68.4%) of hearing loss cases occurred among surface workers. •Coal workers' pneumoconiosis accounted for 14.5% of reported illnesses.

May 15, 2002

By Oliver Bowles

The wire saw, introduced by the Bureau of Mines about two years ago, has revolutionized slate quarrying in Pennsylvania. The success of the saw since its early accomplishments has become greater and greater as the equipment has been perfected and skill acquired .in its use. In the first test made, a cutting rate of 9.7 square feet per hour was attained; in the next four cuts, made early in 1927, the average rate of cutting was increased to 12.8 square feet per hour; in 1928 a maximum of 34 square feet per hour had been attained, with a general average of about 20 to 25 square feet, The wire saw is now regarded as essential equipment in practically all of the quarries in the Bangor, Pen Argyl, and Windgap districts. The wire saw consists of a three-strand steel cable of 3/16 or 1/4 inch diameter running as an endless belt. The driving pulley is a 40-inch double-groove cast-iron sheave. A tension pulley supported by a frame mounted on wheels may travel back and forth on a short track. A weight of 800 to 2,000 pounds gives the desired tension on the wire. The driving units consist of electric motors with direct-drive compactly enclosed gear reduction, or double-belt speed-reduction units; the former is preferred. Silent chain and. pinion gear reductions are used to a limited extent. The travelling speed of the wire is about 15 feet per second. The driving and tension equipment are shown in Figure 1, A.

Jan 1, 1929

In 2007, a total of 725 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Nonmetal mines com-prised 4.9% of all m ining operations. ? Mines producing common clay comprised 25.4% (n=184) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the U.S. Virgin Islands.

Aug 1, 2009

By P. J. Remington

Field measurements utilizing a seat pad accelerometer were made on 61 surface coal mining machines in order to quantify the vibration levels experienced by the operators. Those data were combined with information on the statistics of the operating times of those machines in order to compare the operator's vibration exposure to the criteria in ISO 2631, ?A Guide for the Evaluation of Human Exposure to Whole Body Vibration.? The comparison showed that about ha]f of all surface coal mining machine operators can be expected to be exposed to vibration exceeding the fatigue decreased proficiency criterion, whereas only on the order of 15% would be expected to experience vibration exceeding the exposure limit. Detailed exposure statistics are presented and the implications of the results are discussed.

Jan 1, 1983

By John D. Foulkes, David A. Curtis, Robert L. Lagace, John L. Rothery

An investigation is made of the feasibility of developing compact transmit antennas and/or other means to efficiently couple VLF to MF band radio energy between portable wireless communication units in coal mines. The completely wireless communication ranges between two portable radios equipped with practically-sized reference loop antennas in representative coal mine environments are estimated. Antenna technology is assessed with respect to transmit moment, range, intrinsic safety, battery and wearability requirements to deter- mine the most suitable antenna types for use by miners. It is concluded that air-core bandolier loop antennas, and perhaps ferrite-loaded loop antennas, having peak transmit moments of about 2.5 ampere-m5 will be the most effective antenna choices for portable units. This choice, however, will not allow the range goal of 1350 feet to be attained in mines having unfavorable signal attenuation and noise environments. Rectangular air-core loops are compared with grounded horizontal-wire and vertical-wire mode exciters for fixed station applications. The potential for significantly increasing the wireless communication range by inductively coupling to communications and power lines in a mine is evaluated and found to be considerable based on theoretical coupling equations. Lastly, the theoretical performance of a hybrid noise cancelling diversity receiving technique that utilizes both the electric and magnetic field components of the ambient noise to improve the receiver output signal-to-noise ratio under certain adverse conditions is estimated and shown to be favorable when the magnetic and electric field noise components are highly correlated.

Jan 1, 1977