Search Documents

By Michael J. Sapko, Eric S. Weiss, Kenneth L. Cashdollar

A fundamental safety research area for the National Institute for Occupational Safety and Health (NIOSH) is to eliminate the occurrence of coal mine explosions or to mitigate their effects. One approach is to develop and evaluate new and innovative seal designs that provide increased explosion protection for mining personnel. The NIOSH Pittsburgh Research Laboratory (PRL) cooperated with HeiTech Corp. of Virginia, Barclay Mowlem Construction Ltd. of Queensland, Australia, and the Mine Safety and Health Administration (MSHA) in three separate research programs to evaluate the strength characteristics and air leakage resistance of numerous innovative seal designs and ventilation control structures for use in underground coal mines. For each phase of the program, various full-scale seals, stoppings, and an overcast design were constructed in PRL's Lake Lynn Experimental Mine near Fairchance, Fayette County, PA. The seals and stoppings were built in crosscuts and were subjected to explosions to evaluate their strengths. Four pumpable cementitious seal designs ranging in thickness from 610 to 915 mm (24 to 36 in) were evaluated in the first cost-reimbursable research program with HeiTech Corp. A simple wooden framework with brattice liner was used as a form to contain the cementitious slurry during the curing period. As the seal designs decreased in thickness, higher compressive strength cementitious grout was used. All four seals withstood an explosion pressure pulse of at least 138 kPa (20 psi) while maintaining acceptable air leakage resistance. In the second cost-reimbursable research program with Barclay Mowlem Construction Ltd. of Australia, several innovative seal and stopping designs and an overcast design were evaluated. Each of the seal designs and the overcast side and wing walls used one or more air-inflated vinyl bladder assemblies anchored to the mine roof and hitched into the ribs and floor. The air within these bladders was displaced with a high-strength cementitious grout. The overcast deck consisted of a 200-mm ('7.8-in) thick reinforced cementitious slab. This was the first time that an overcast structure had been explosion tested under full-scale conditions. All of the seals, stoppings, and overcast design passed the air leakage tests before being subjected to a series of explosions with static pressure pulses ranging from 14 to 475 kPa (2 tab 69 psi). Instrumentation measured seal and overcast wall displacement as a function of time. The 450-mm (1 7.7-in) thick seal in the 2.8-m(9-ft) high third crosscut withstood an explosion pressure of 170 kPa (25 psi), but failed during a later test, which generated a peak static pressure of 475 kPa (69 psi) at the seal location. A similar 450-mm-thick seal in the 2.1-m (7-ft) high second crosscut withstood three explosion tests, which generated peak static pressures of 195, 205, and 370 kPa (28, 30, and 54 psi) at the seal location. Next, the overcast design withstood four explosions, which generated static overpressures ranging from 16 to 47 kPa (2.3 to 6.8 psi). A third program at the request of MSHA evaluated the effectiveness of using pressurized grout bags (Packsetter bags) along the mine roof and ribs in lieu of floor and rib hitching for a standard-type solid- concrete-block seal. This program was initiated to address an urlusual geological mining condition encountered when building seals in entries where required rib hitching is not a viable option due to soft friable coal. Results showed that the use of these quick-setting grout-filled Packsetter bags pressurized internally to 300 kPa (44 psi) not only provides a seal that can withstand a 138-kPa static pressure explosion, but also provides a sealing option where rib hitching is not possible.

Jan 1, 2003

By W. W. Simpson

The Bureau of Mines conducted research to determine the effects of potassium trithiocarbonate (KTTC), a degradation product of potassium ethylxanthate (KEX), on flotation of chalcopyrite and molybdenite. Small amounts of KTTC were identified in fresh and aged solutions of KEX using thin-layer chromotography. Hallimond tube flotation tests on pure minerals showed that KTTC acts as a weak collector for chalcopyrite. Both KEX and KTTC tend to depress molybdenite, but the depression effect is easily overcome by addition of a small quantity of fuel oil. The results of the Hallimond tube tests were confirmed in batch flotation tests using a porphyry copper ore.

Jan 1, 1983

By E. M. SEELEY, F. S. LOTT

Expansion in total capacity of the natural-gasoline industry.to produce light products continued in 1944 and 1945. The average rate of gain, however, was reduced to about 6 percent annually from over 9 percent in the preceding 4-year period. New facilities at cycle plants again accounted for most of the increase in productive capacity. Between January 1, 1944, and January 1, 1946, the number of cycle plants increased from 32 to 37 and their total capacity from 3,278 thousand gallons daily to 4,848 thousand (48 percent). Capacity of all other plants in the industry increased in the same period from 12,735 thousand gallons daily to 13,080 thousand, or only 3 percent. The capacity of the average plant increased to 28,600 gallons a day from 24,400 gallons on January 1, 1944, continuing the established trend. The average capacity of cycle plants increased to 131,000 gallons a day from 102,400 gallons, and the average capacity of all other natural-gasoline plants increased to 22,200 gallons a day from 20,400 gallons. Although the number of plants increased in only three States in the 2-year period (Texas, Okla- homa, and Arkansas), the total capacity of plants increased in eight States. A further decline of 29 reduced the total number of plants to 626 on January 1, 1946. Compared with 10 years earlier, gasoline plants were more numerous in only 4 States: Texas (48 more), New Mexico (7 more), Arkansas (2 more), and Louisiana (1 more). The largest declines, in order, were in Oklahoma, Illinois, Pennsylvania, West Virginia, and California. The number of plants with fractionating equipment for separating the liquefied gases from heavier fractions was 202 on January 1, 1946 and 182 2 years earlier. The principal changes in number and capacity of shut-down plants were an increase in Texas and a decrease in California. Shut-down natural-gaso- line plants are usually among the smallest units in their vicinity.

Apr 1, 1947

Objective As mines become safer and disasters fewer, a time may come when no employees in the mining industry have any practical experience in managing a mine emergency. To fill an emerging gap in mine emergency response training, a multidisciplinary team of researchers and computer programmers from the NIOSH Pittsburgh Research Laboratory has developed an intervention for mining personnel who would be in leadership positions in the command center during emergencies. It is called MERITS, a computer-based emergency simulation exercise. MERITS is short for "Mine Emergency Response Interactive Training Simulation." It provides trainees an opportunity to gain command center experience during a simulated underground coal mine emergency. MERITS allows trainees to practice information gathering, situation assessment, decision-making, and coordination skills without risk to personnel or property. Individuals representing mine emergency response personnel, various State safety officials, and private mine management from three States have participated in MERITS training. What Is MERITS? MERITS is an extension of previous work that compiled a knowledge base relevant to mine disaster management via interviews, analysis of literature, reviews of past events, and observations of mock mine disasters. Findings from prior research found a need for an alternative method of command center training. This new computer simulation is being used to train emergency command center personnel to effectively manage an underground mine fire. Modeled after training simulations developed for other industries (e.g., to address nuclear accidents, chemical spills, evacuations, etc.), MERITS simulates underground and surface events related to the disaster. It exposes the user to events that typically occur during a mine emergency, such as lack of information and miscommunication. It also presents trainees with issues that must be addressed, such as making provisions for briefing news media and victims' families, ordering needed supplies, interfacing with Government enforcement agencies, and housing mine rescue teams. The outcome of the scenario is determined by the users' decisions and their emergency response plans. Field Results Field testing of MERITS was conducted with eight full-day training sessions at four different locations in Colorado, Pennsylvania, and West Virginia. These field tests benefited from the knowledge and experience of State of Pennsylvania inspection officials, representatives of the United Mine Workers of America(UMWA), and private mine management who served as trainees for the MERITS training sessions. Trainees self-reported an average of20 years of work experience in the mining industry. All trainees had participated in Mine Emergency Response Development (MERD) training exercises, and many had been involved in real mine emergencies. Trainee evaluation of the MERITS program is summarized below: •Twenty-six of the 27 trainees believed that the MERITS simulation helped them know how to prepare for a real emergency. •Twenty-five of the 27 trainees believed that the storyline for the MERITS simulation was either "very realistic" or "realistic." •All 27 trainees believed that the MERITS simulation helped them learn how to better handle a real emergency. •None of the 27 trainees stated that they were bored during the simulation. After the initial field tests, MERITS was refined and retested during training sessions for individuals from State agencies, the UMWA, and private industry. Mining personnel from underground coal and underground stone mines participated and responded positively to the learning experience. Technology Transfer Industry introduction to the MERITS program will occur throughout 2002. MERITS presentations at the Joseph A. Holmes Safety Association National Meeting in Virginia Beach, VA, in June.

Jun 1, 2002

By William J. Campbell

This analytical method development and evaluation was undertaken by the Bureau of Mines to provide accurate determinations of eight minor elements in low-alloy steels prepared from ferrous scrap. Fluorescent X-ray spectrography was the principal method investigated. Confirming analyses were made by conventional instrumental and chemical methods. All X-ray data were processed by a timesharing computer. No corrections were found necessary for inter-element effects or overlapping spectral lines. Concentrations were calculated from the least-square fit of a linear calibration equation derived from measurements on three sets of standard steels. These studies show that X-ray spectrographic analysis of lathe-finished surfaces provides accurate determinations of aluminum, copper, chromium, manganese, nickel, phosphorus, silicon, and tin.

Jan 1, 1973

By P. L. Woolf

An investigation was conducted to evaluate the use of a formcoke as the total fuel in the Bureau of Mines experimental blast furnace. The formcoke performed very satisfactorily, and comparisons made with a metallurgical coke showed that the performance with the formcoke was somewhat superior under the experimental conditions used.

Jan 1, 1966

By W. H. Ode, W. A. Selvig

"INTR0DUCTIONAccording to the Standard Specifications for Classification of Coals by Rank of the American Society for Testing Materials (A.S.T.M. Designation: D388-38).1/ high-volatile bituminous coals, subbituminous coals, and lignites are classified on the basis of calorific values on the ""moist"", mineral-matter-free basis. The moist basis refers to coal containing its natural bed moisture but not including visible water on the surface of the coal. It is assumed that the natural bed moisture of coal in the ground represents the moisture-holding capacity of the coal when in equilibrium with air at approximately 100 percent relative humidity. This moisture is sometimes referred to as inherent moisture as opposed to extraneous moisture, which wets the surface of the coal.To simplify procedures for determining the moisture-holding capacity of coal it is assumed, for all practical purposes that the moisture content of coal when brought to a standard condition of moisture equilibrium in an atmosphere of 97 percent relative humidity and 300 C. represents the bed moisture of the coal. The A.3.T.M. specifications provide that this condition of moisture equilibrium shall be obtained by bringing the coal to a standard condition of moisture equilibrium at 300 C. in a vacuum desiccator containing a saturated solution of potassium sulfate (97 percent relative humidity) according to the procedure proposed by Stanfield and Gilbart. 4/ No mention is made in the specifications for bringing partly air-dried samples to their natural bed moisture condition probably because of the hysteresis effect that has been noted by various investigators. 5/ In this connection it has been found from sorption studies that the adsorption and desorption curves for lignite are not entirely reversible. The hysteresis effect has been explained by some investigators as resulting from shrinkage of the lignite during drying, which causes a collapse of some of the capillaries, so the dried lignite cannot take up as much water as it held originally."

Apr 1, 1953

By G. R. Hopkins

The petroleum-refining industry established a new record in fuel efficiency at refineries in 1936, when 597,000 B. t. u. of heat were required to refine a barrel of crude oil, compared with an average of 615,000 B. t. u. in 1935 (see fig. 1). The principal factor in the "indicated gain in fuel efficiency at refineries in 1936 was an increase in crude runs of 11 percent over 1935. A large part of the heat utilized at refineries is consumed elsewhere than under stills, or in ways quite independent of crude-oil distillation. In other words, as the operating ratio (crude runs divided by capacity) for refineries increases toward the maximum of 100 percent, the fuel requirements show progressively smaller increases and the average E. t. u. consumption per barrel of crude refined declines.

Jan 1, 1938

By Robert M. Doerr

The oxidation kinetics of Ni-Y alloys in the range 0.04 to 8 weight-percent Y, and of high-purity Ni, were compared by the use of a sensitive volumetric apparatus. The reactions followed approximately the parabolic rate law; for oxidations in 02 at 0.5 atm and 1,200° C, the parabolic rate constant was about 0.37 + (0.064) (Y-2.11) mg cm-2 min-1/2, where Y represents the weight-percent Y in the alloy. Internal oxidation of Y occurred in the alloy specimens and the resultant Y203 particles, which were in patterns related to the eutectic structure of the alloys, served as markers showing that the subsequent oxidation of the surrounding Ni was by inward diffusion of O. The scale consisted in each case of NiO, but the inner parts of the scale on the alloy specimens included the patterned Y203 particles. The thicknesses of the inner parts of the scale depended directly on the Y concentration, and the thicknesses of the Y2O3-free outer parts of the scale were inversely related to the Y content of the alloys. There is thus a relationship between the thickness of the outer part of the scale and the protectivity of the scale. Outward diffusion of Ni and inward movement of 0, from the inner boundary of the Y2O3-free part of the scale, is proposed as a mechanism for these results.

Jan 1, 1966

By F. W. Wood

The method described may be used to delineate irregularities, inclusions, porosity, or shrink holes in ingots up to 43 inches in length. Rou¬tine testing does not require technical personnel, and the equipment is easily maintained. INTRODUCTION For a number of years, the Northwest Electrodevelopment Laboratory of the Bureau of Mines, Albany, Oreg., under contract with the Atomic Energy Commission and the Naval Reactors Division of the Bureau of Ships, has studied the production of zirconium and has adopted the Kroll magnesium-reduction process3/ as the, most economical means of producing high-purity zirconium sponge in quantities commensurate with demand. Consumable-electrode arc melting4/ provides a practical means of melting the sponge without increasing the impurity content. The ultimate application for which the metal is intended requires that strict specifications be met to insure workability and maintain the nuclear properties and corrosion resistance. The control measures employed to satisfy these specifications include chemical, spectrographic, and metallographic analyses, mechanical and corrosion tests, and ultrasonic inspection of the finished ingot. The primary purpose of ultrasonic inspection is to augment the other control measures by checking the soundness of each ingot leaving the laboratory. An incidental but important function has been the revelation of information leading to better understanding of the arc-melting process. For example, information obtained through ultrasonic inspection relative to the occurrence and distribution of porosity in ingots has resulted in a. modification of melting practices that minimizes the occurrence.

Jan 1, 1955

By J. B. Gayle

Coke-pushing difficulties have been the subject of much controversy but relatively little scientific investigation. Nevertheless, continuing pushing difficulties can greatly decrease the life of a coke oven and should therefore be considered in the selection of the blend and operating conditions used for coke production. The present Federal Bureau of Mines investigation was undertaken to correlate results of previous investigators and to supplement these results to the limited extent practical by us of an experimental slot-type oven. To this end, pushing pressures have been determined routinely for Tuscaloosa oven tests conducted during the past 10 years. Nevertheless, the accumulated information remains incomplete in many respects, and in view of the recognized inadequacies of the data, publication is now undertaken only because of the scarcity of published information on this important problem and the discontinuation of carbonization studies with this oven.

Jan 1, 1961

By C. I. Pierce

The Bureau of Mines used an electrolytic tank model to investigate the response of guard electrodes of different dimensions under different simulated reservoir conditions. Sandstone disks from the Berea and Connellsville Formations were used as resistive beds in the model, and agar gel or water was used as conductive beds. In the experiments, bed thickness, hole diameter, mud resistivity, and bed resistivity were varied. The guard electrode is an excellent tool for determining true bed resistivity in the thin-bedded oil reservoirs of the Appalachian area. Vertical resolution and resistivity values are good when there is little or no invasion. Resistivity values are near true bed resistivity in beds thicker than about six hole diameters when the electrode-to-hole-diameter ratio is close to 1. However, low-resistivity muds cause false peaks to appear on the logs near bed boundaries in thick beds, and for resistive beds having a thickness approximately three to five times the hole diameter, apparent resistivities tend to be excessively high when mud resistivity is low.

Jan 1, 1966

By Fred D. DeVaney

Copper sulphate is a common flotation reagent for blonde ores. Metallic iron also is present in the mill circuit, and a reaction between the iron and the salt would be in accord with well-known chemistry. The abundance of metallic iron in a flotation food may be noted by even perfunctory examination. First of all the mine contributes metallic iron, then the coarse-crushing machines add their share, and finally the fine-grinding medium its portion. If the grinding is with cast-iron balls the amount of metallics is greater than when steel is used. Thus it, is that much more metallic iron is present than would be indicated by noting the ball consumption. An estimate that the total amount of metallics is twice that supplied by the balls and liners might not be far amiss. That copper sulphate plates out on iron in an acid solution is well known, but since flotation is practiced commonly in solutions where acid has not been added this reaction has not been given sufficient thought.

Jan 1, 1929

To reduce operator exposure to noise from vibrating screens at coal preparation plants. Background Hearing loss is one of the most common occupational illnesses in the United States. In the U.S. mining industry, hearing loss is 2.5 to 3 times greater than what is expected for the average population that is not exposed to occupational noise. Furthermore, studies by the National Institute for Occupational Safety and Health (NIOSH) showed that by age 50, 90% of coal miners have a hearing impairment versus only 10% of the population that is not exposed to occupational noise. A NIOSH cross-sectional survey of coal preparation plants showed that 43.5% of employees were overexposed to noise. The study also found that vibrating screens were one of the top five loudest types of equipment at these plants?as well as the most numerous?making them a key noise source to address.

Nov 1, 2009

By H. S. Auvil, J. T. McCartney, J. D. Davis

"INTRODUCTION It is now generally recognized that the small-scale laboratory dilatometer method of test does not give results of much utility in predicting the expansion (or contraction) of a coal in a coke oven. The carbonizing conditions in the laboratory test differ radically from those in the oven; in this test, the charge is heated through the coking range of temperature as a whole, whereas in the oven, coking proceeds by layers parallel to the oven walls as each succeeding portion of the charge goes through the plastic range of temperature and coke formation sets in. The paths of the gases and vapors and the pressures set up are different in the two methods. Furthermore, the rate of heating in the test usually is much more rapid than in the oven. H. Koppers 5/ was perhaps the first to adopt apparatus and procedure whereby the layer coking of the coke oven could be simulated closely however, the heating progressed from one side of the charge only; later he experimented with a small coke oven with a movable wall heated from both sides. It is not clear how well the results in the later oven correlated with those of the earlier small test oven, but in a comparatively recent Koppers publication a modification of the original small test oven heated from one side is recommended 6/ Altieri 7/ was perhaps the first to experiment with the Koppers type small test oven in the United States and Brown- has tested a large variety of coals in a rectangular test oven of his own design heated from the sole or floor. Subcommittee XV of American Society for Testing Materials Committee D-5 is now making a study of the various methods proposed for determination of expanding and plastic properties of coal with a view to standardization. 9/"

May 1, 1939

By P. M. Sullivan

This report describes a new application of electroamalgam metallurgy in recovering all the zinc as refined metal from galvanizers' sal skimmings. Pure zinc was recovered by electrolysis of skimmings leach liquors in amalgam cells. The following information was gained as a result of literature studies and subsequent laboratory investigations. 1. Reports in the literature indicate that pure zinc can be recovered from chloride solutions with the aid of amalgam cells. From Europe it was reported that amalgam cells could be used to recover pure zinc and chlorine from leach liquor obtained from pyrite cinders following a chloridizing roast.

Jan 1, 1956

By Oliver Bowles

This report covers the character, properties, origin, occurrence, and uses of the traprocks and describes briefly the methods and equipment employed in quarrying and preparing them for market. Production of traprock occupies an important place in industry. In 1960 the output in the form of crushed stone reached nearly 58 million tons valued at $87 million. Traprocks are also shaped into blocks of dimension stone for monuments, building construction and decoration, and specialized products such as surface plates.

Jan 1, 1963

By Lorenz E. Sieffert, Lawrence B. Berger, H. H. Sehrenk, Ralph W. Stewar, James A. Gale

"INTRODUCTION The purpose of the investigation discussed in this article was to evaluate the toxic hazard from gases produced when thermosetting plastic materials used for electrical insulating purposes are burned or thermally decomposed in enclosed spaces. For brevity the term ""toxicity"" is used throughout the article to refer to the nature of gases produced under these conditions. A need for immediate study of the problem was created as a re¬sult of the battle damage reports received from various United States Fleet units. These indicated that the fumes emitted when these materials were burned or thermally decomposed had, in several instances, resulted in toxic atmospheres. In attempting to develop a suitable test method for evaluating toxicity, it was recognized that no single test procedure could be expected to duplicate the variety of conditions that might exist in an actual fire aboard ship. In view of the immediate need, however, it was felt that considerable information could be obtained, at least to classify comparatively the several types of materials as to the toxic effect caused by burning or thermal decomposition, through the development of a sound empirical method which could be applied to all of the materials. On this basis, it was decided to modify the Navy flame resistance test for thermosetting plastics to render it applicable to the determination of the toxic, gases evolved when this test was employed. A wide variety of materials was tested, both molded and laminated, to cover the types commonly used by the Navy in electrical applications. Toxicity determinations were conducted at the Bureau of Mines Central Experiment Station, Pittsburgh, Pa. Parallel tests, to determine the flame resistance of the materials, were conducted at the Material Laboratory, U. S. Navy Yard, New York, N. Y."

Oct 1, 1947

By Marcia L. Harris

Toxic fumes produced by detonating explosives in surface mining and construction operations pose potential hazards to workers and the public. Blasting operations produce both toxic and nontoxic gaseous products; the toxic products are mainly carbon monoxide (CO) and the oxides of nitrogen (NOx). Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings as well as one fatality. At worst people may be fatally poisoned and the least to be expected is increased public objections to blasting. Local and state agencies could demand a cessation of the blasting requiring more expensive mechanical means to break the rock. This paper discusses the most feasible means of preventing CO migration, mitigating CO that has migrated, and detecting CO in an underground enclosed space and may help reduce the exposure of unsuspecting area residents to carbon monoxide and help prevent the implementation of unnecessary regulations and limitations on blasting. Single-hole shots and small-scale multiple-hole blasts were performed that indicate promising means of prevention and mitigation.

Jan 1, 2008

By Errol D. Sehnke

This U.S. Bureau of Mines report provides detailed information on worldwide alumina production capacity by plant and country. The information was compiled from a variety of domestic and international sources and was based on information available to the Bureau through December 31, 1993. Capacity data represent announced installed and planned capacities and do not necessarily reflect a Bureau of Mines judgment of actual plant operating levels or timing of planned expansions, The year-end capacity is the ?nameplate" capacity or estimated production capacity, whichever is larger.

Jan 1, 1993