Search Documents

By Oliver Q. Leone

Electrorefining tests using titanium-nitrogen alloys as anode material showed that no significant quantity of nitrogen was transferred to the cathode deposit. The nitrogen of the anode remained in the scale, and the titanium-nitrogen alloy was anodically insoluble in the electrolyte when the nitrogen content was 11 weight-percent.

Jan 1, 1966

By Jack I. Paige

In this Bureau of Mines study, two fluidized-bed reactors were designed, built, and operated, one as a sorber for S02 and the other as a contactor for the regeneration of the sulfur-laden alkalized alumina. The target of 90 percent removal of S02 from a flue gas stream containing 0.3 percent S02 was attained by using a sorbent feed of 10-15 grams per minute into a 5-inch bed depth of alkalized alumina. The sorption unit was operated at about 330° C. Complete regeneration of the laden alkalized alumina containing 5 to 10 percent sulfur was accomplished in approximately 1/2 hour. An excess of reformed propane at about 730° C was the regenerating gas. Attrition losses, a major problem with this sorbent, ranged from 0.9 to 7.9 percent of the inventory. Data from these tests demonstrate, within experimental error, the validity of equations developed from short-term, thin-bed tests related to sorption and regeneration rates.

Jan 1, 1970

By W. Miola, R. V. Ramaoi

"The MSHA prescribed method for the determination of quartz in airborne respirable-dust samples from underground coal mines is the P-7 method, a combination of /ow-temperature, radio-frequency ashing (LTA) and infra7 red analysis (IR). There is no prescribed procedure for quartz analysis in bulk samples of coal and host rock. Dispersive infrared (IR), Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) methods are most commonly used for the analysis of quartz in powders. Several aspects of the experimental procedures, such as the preparation of the analysis sample from bulk samples, ashing techniques, scanning procedures, peak measurement location, calibration techniques, sample amounts, size consist and data interpretation, affect the results from each of the methods differently. Significant differences in analytical results obtained from X-ray diffraction (XRD) and infrared spectroscopy (IR) on the same samples are reported. All studies point to the need for reliable quartz analysis methods.In a recent research program, a procedure for preparing bulk-coal and host-rock samples for quantitative quartz analysis was developed. Further, the results from X-ray diffractometry and infrared spectroscopy for quartz content on identical samples were compared. Calibrations with pure and mixed standards were used to assess the influence of particle-size distribution, matrix and calibration on the analytical results. In this paper, several issues concerning the measurement of quartz in the samples of coal, host-rock and airborne respirable dust from mines are outlined and quantified. IntroductionThe literature on coal-mine airborne-dust control has identified a need for a better understanding of the sources, mechanisms and amounts of quartz in mine airborne respirable dust (Althouse, 1984; Jankowski, Nesbit and Kissel, 1985; Ramani 1988; Qin, 1988; Bhaskar and Xu, 1990; Bhaskar and Li, 1992; Ramani, Qin and Miola, 1991 ). To understand the quartz content in the source materials, bulk samples of coal and host rock must be analyzed. Establishing an analysis procedure for determining the quartz content in bulk-coal and host-rock samples is necessary for identifying the sources of quartz in mines; for establishing the relationships between the quartz contained in the source and in the airborne dust; and for controlling the content of quartz in the mined product and in the airborne respirable dust."

Dec 1, 1996

By Bertrand L. Johnson

As potash is more necessary to the agricultural economy of the United States now than ever before it is gratifying to find that the virtual stoppage of imports from Germany in late 1939 caused none of the anxious foreboding that gripped American farmers in 1914. For long decades this country, in common with tie rest of the world, depended upon German potash, but today our expanded needs can be mot from domestic sources. The present armed conflict in Europe, like that of 1914, disrupted a world monopoly, but the cartel that in recent years controlled 90 percent of the world output (see fig, 1) was an international syndicate comprising French, Polish, and Spanish as well as German producers and having reported sales agreements covering production in the U. S. S. R. and Palestine. The break-up of these commercial agreements has necessitated readjustments but generates no such alarm as the closing of a single source of supply. In striking contrast to the critical shortage that developed a quarter century ago, no increase in prices has occurred or is anticipated in the domestic market.

Jan 1, 1940

By Margaret E. Egan

Reliable fire detection is essential for both safe evacuation and containment or extinguishment. In order to increase reliability by reducing the number of nuisance fire alarms in underground mines that use diesel-powered equipment, the U.S. Bureau of Mines has developed a diesel-discriminating fire detector (DDD). It was designed to discriminate between smoke produced by a fire and the smoke-laden exhaust of a diesel engine. Experiments were conducted by the Bureau to compare the smoke detection capabilities of the DDD with those of conventional fire detectors in response to smoldering coal and conveyor belting. A comparison was made among the alarm times of a carbon monoxide (CO) detector with an alarm threshold of 5 ppm, a smoke detector with an optical density alarm threshold of 0.044 of', and the DDD with an alarm threshold of 0.025 V. The results show that the DDD will reliably detect developing coal and conveyor belt fires. The average time delay separating the DDD alarm from the first detector to alarm was 76 s for smoldering conveyor belt and 65 s for smoldering coal. The longest time delay between the response of the DDD and the first detector to alarm was approximately 120 s.

Jan 1, 1993

The Bureau of Mines, U.S. Department of the Interior, devised a flotation technique for upgrading chromite in chromium ores and gravity concentrates. The technique consisted of cationic flotation of chromite from a slime-free pulp acidified to pH 2.5 or lower using H2S04 modifier. Flotation results showed that ore containing serpentine as the primary gangue mineral was more amenable to concentration by this technique than ore containing the readily floatable olivine as the primary gangue mineral. Rougher flotation of a chromite ore containing abundant serpertine increased the grade form 19 to 41 percent Cra03 at a chromite recovery of 89.6 percent. Rougher flotation of ore containing abundant olivine upgraded the chromite from 23.4 to 29.6 percent Cr203 at a recovery of 89.4 percent. The technique was also applied to chromite gravity concentrates to further upgrade chromite and to reject silicates. Flotation of a gravity concentrate containing 40.9 percent Cr203 and 4.4 percent SiO2 recovered 90 percent of the chromite in cleaner products containing 44.9 percent Cr203 and 0.63 percent Si02. The combined recovery by gravity and flotation was 87 percent. An economic evaluation of this technique will be undertaken to deter-mine its feasibility for commercial use.

Jan 1, 1980

By Griffith. F. E., Glei

"INTRODUCTION For many years protective grounding of electrical equipment has been advocated as a means of safeguarding equipment against damage and of minimizing shock hazards to persons. Several codes are in effect covering in considerable detail the items to be observed in obtaining effective grounding in and about industrial plants. Although the coal-mining industry does not have a comprehensive code of its own covering the grounding of electrical installations, a number of States and individual coal-mining companies have issued codes, standards, or rules that include certain requirements with reference to grounding. As early as 1916, 4/ and again more recently, 5/ the Bureau of Mines recommended grounding, particularly as a means of preventing shock to men working on or around electrical equipment.It is common knowledge among electrical engineers of public utility and mining companies that connecting a wire from the frame of a machine to a rod or pipe driven into the earth does not necessarily assure desired protection of surface equipment. In fact, it has often been found necessary to use several interconnected rods and to treat the surrounding earth with salt or other chemicals before the connection to earth would have sufficiently low resistance to give satisfactory results. Even these expedients have not produced the desired results in some localities. It has also been found that ground connections initially having a low resistance may attain high resistance during some seasons of the year. In spite of such difficulties with surface equipment, it has sometimes been assumed that a mining machine resting on the floor in a coal mine is grounded by virtue of its contact with that floor. It has also been assumed by persons endeavoring to comply with grounding requirements that a peg or rod driven into the mine floor would provide a sufficiently low-resistance contact with the earth to be satisfactory as an electrode for connecting the grounding wire from frames of equipment. That both assumptions may be wholly untrustworthy has been proved by the authors in actual tests with underground machinery."

Dec 1, 1943

By Andrew B. Cecala

The U.S. Bureau of Mines has designed and evaluated total mill ventilation systems at two different mineral processing operations. Both systems have proven very effective at reducing respirable dust levels throughout the mill in a cost-effective manner. A 25,500-cfm system installed at a clay processing mill provided approximately 10 air changes per hour. This system reduced respirable dust concentrations by approximately 40 pct throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 50,000 and 100,000 cfm of ventilation to the mill building, corresponding to 17 and 34 air changes per hour. Average mill-wide respirable dust reductions were 36 and 64 pct, respectively. Not only did these systems reduce respirable dust concentrations and increase visibility throughout the mills, they were also easy to install and required minimal maintenance. A total mill ventilation system provides a general purging of the mill air; the system should be viewed as a supplemental technique to assist other dust control systems in operation.

Jan 1, 2010

By Joseph S. Coffman

To determine the availability of manganese for metallurgical purposes from selected world resources, the Bureau of Mines evaluated the potential production of contained manganese in concentrates based on the demonstrated resources of 23 foreign and 8 domestic mines and deposits in 9 market economy countries. All but 2 of the 23 foreign deposits are operating mines; none of the domestic deposits are in operation. The demonstrated resources of the mines and deposits used in this study represent an in situ ore resource of approximately 2.2 billion tons," containing 780 million tons of manganese with a total recoverable production potential of 514 million tons of contained manganese in concentrates. The analyses of mines and deposits in this study indicate that about 213 million tons of the contained manganese (41 pct) is potentially available at a January 1981 constant dollar long-run total cost of up to $1.50 per long ton unit (22.4 lb, or 10.15 kg contained Mn), approximately 428 million tons (83 pet) is potentially available at a cost of about $1.75 or less, and 491 million tons (95 pet) is available at less than $3.30. The remaining 23 million tons, which is potentially available at much higher costs (about $8 to $35 per unit), represents the U.S. deposits. On an annual basis, with a cost range of up to $1.75 per long ton unit, the availability from currently operating mines would last at least 80 years based on 1980 world production data. Total manganese production costs are estimated to comprise mining-8 pet, beneficiation-3 pet, transportation-26 pet, and smelting-63 pet.

Jan 1, 1984

By M. J. Kovalik

The effect of oxidation by air at temperatures ranging from 200° to 390° C on the change of chemical and physical properties of Pittsburgh-bed coal was studied as a function of processing time and temperature. The goal was to prepare a nonagglomerating fuel from a strongly coking coal for use in continuous carbonizing processes and in fixed-bed gasifiers. The oxidized coal was carbonized in a bench-scale apparatus, and the coke strength was evaluated in a Roga tumbler. Strength of the coke was progressively reduced with time of oxidation until the coking power of the coal was apparently destroyed. Time requirements to obtain an essentially nonagglomerating product were inversely related to processing temperature. Gaseous products released from the coal during oxidation reduced the yield of the desired nonagglomerating product, which decreased with time of oxidation at constant temperature and with increase in processing temperature at equal time. Oxidation at a temperature slightly above the lower limit of the plastic temperature range of Pittsburgh-bed coal was most effective because of the short processing time required and moderate processing losses.

Jan 1, 1963

By John B. Gayle

[The coking time exerts a Considerable influence on the throughout of a coke oven, and for this reason a large number of papers dealing with the relation between coking tine and the different operating variables have been published. Although all of the factors known to ink influence the coking time have been studied, agreement leas not boon reached on several questions, 3/4/ and it appears worthwhile to evaluate any data that become available during investigations of the carbonizing properties of various oafs and coat blends, this report, therefore, includes a Study of the relation between coking lime and flue temperature and represents the second phase of overall investigation ion of factors influencing the coking time in slot-type ovens.]

Jan 1, 1956

By Victor Himel

This report documents a systematic approach towards implementing an improved ensemble for the mine rescue team system that will protect against the hazards of mine rescue and recovery and will also afford improved performance through increased comfort and maneuverability, lighter burdens, and improved human engineering designs. In the first part (Task 1) the mine rescue team's protective needs were defined along with the test methods required to evaluate whether a particular piece of gear met these needs. Task 2 assessed existing gear against performance criteria and standards developed in Task 1. Task 3 consisted of the conceptual design and construction phases of the MRPE program. Special consideration was given to advanced concepts, materials, and equipment.

Jan 1, 1982

By J. A. Herdlick

The Star mine, near Neihart, Cascade County, Mont., has been in continuous operation since the construction of a 50-ton bulk flotation mill in 1939. The mine was examined by G. N. Bennett, an engineer of the Bureau of Mines, in November 1942. At that time the life of the operation appeared to be limited and a program of crosscutting and core drilling were recommended. The program had as its objective the investigation of a promising undeveloped area lying west of the Star vein and, if possible, the development of enough reserves in this area to insure continuous operation during the war emergency. Development of additional reserves would then justify necessary changes in the mill in order to eliminate the heavy penalties imposed for excess zinc in the bulk concentrates. The Bureau of Mines work began in February 1944 and was completed in September 1944. The project was started by Wilder R. Brinton and continued by Thomas W. Oster, mining engineers in the Bureau's Montana district office. Beneficiation tests on are and concentrates were made after completion of the underground work. This report presents the factual data obtained during all phases of the Bureau's investigation.

Jan 1, 1949

By William D. Monaghan

The U.S. Bureau of Mines evaluated a teleoperated continuous mining machine for deep mining in thin-seam applications as low as 1 m. Teleoperation increases the safety of mining machine operators because it removes the operator from the face, an area of immediate hazards to safer outby locations. By using teleoperation, the miner can avoid many including unexpected roof falls that can maim or kill miners instantly, methane and coal dust explosions that can be ignited with just a small spark or flame, adverse health effects from miners breathing coal and silica dust, adverse long-term inner ear damage from loud noise pollution, and other hazards related to heavy mining equipment moving about in confined underground roadways. This report presents the surface evaluation results of a teleoperated control system.

Jan 1, 1994

By John R. Reigart

The Tri-State district, as its name indicates, is composed of portions of three States, the southeastern corner of Kansas, the northeastern corner of Oklahoma, and an adjacent strip of Missouri east of these portions of Kansas and Oklahoma. An area approximately 40 miles long in a northeasterly-southwesterly direction, and 30 miles wide at right angles thereto, containing minable occurrences of ore at widely scattered locations, comprises the district. However, what has been and is the main productive area, is a strip about 35 miles long and 10 miles wide, which begins at Miami, Okla., as its southern extremity and runs in a northeasterly direction through Commerce, Picher, and Hockerville, Okla., Baxter Springs and Galena, Kans., and Joplin, Webb City-Carterville and Carthage, Mo. Almost the entire present production comes from the area between Commerce and Baxter Springs.

Jan 1, 1932

By Martin Hertzberg

The concept of limit burning velocities is used to formulate a quantitative theory of flammability limits. Competing processes dissipate power from a combustion wave and quench propagation at some characteristically low limit velocity. There are four competing processes and one complication: (a) Free, buoyant convection, (b) conductive-convective wall losses, (c) radiation, (d) selective, diffusional demixing (the complication), and (e) flow gradient effects (flame stretch). These complexities are unraveled by creating an idealization that is initially freed from these competing processes. The ideal serves as a standard, and its burning velocity (Su), ideal is a unique function of the initial thermodynamic variables of state. By adding each process individually, it is possible to evaluate their significance, quantitatively, in terms of a limit velocity (Su)a , b , c , or e , and to explore the nature of their cooperative interactions. The larger the limit velocity, the more significant the process. The apparently diverse observations of flammability behavior are readily unified within this simple, conceptual framework.

Jan 1, 1976

By James P. Ulery, Frank E. Chase

Clay veins found in coal mines have caused numerous injuries and fatalities. These structures plague all phases of mining, including entry development, pillar recovery, and panel extraction. Clay veins also increase production costs and may disrupt or halt mining. These detrimental aspects have prompted the Bureau of Mines to investigate the physical characteristics of and roof instability problems associated with clay veins. This was accomplished by observing and mapping clay veins in surface and underground mines. The occurrence and origins of clay veins were also investigated to determine predictive capabilities. The investigators found that clay veins normally occur in more stable, less rapidly subsiding coal basins. Clay veins result when tensile stresses develop fissures which are later infilled. These fissures can be propagated by compactional processes and/or tectonic stresses active during and subsequent to coalification. The Bureau also found that associated faults, fractures, and slicken-side planes commonly parallel clay veins and disrupt the lateral continuity of the immediate and, sometimes, main roof. When clay veins parallel or subparallel the direction of face advance, the roof is segmented into cantilever beams, causing unstable conditions. Consequently, the strata on either side of the clay veins should be bolted and strapped together to form a beam.

Jan 1, 1987

By Floyd G. Anderson

The increasing trend toward use of continuous-type mining machines created a significant dust problem in coal mining, which resolved itself into three categories: Visibility at face, deposition on return airways, and the potential health hazard. The control measures applicable to these conditions and studied or developed from 1955 through 1957 are summarized and reviewed in this report. Other important problems brought into focus during the same period were radiation exposure in uranium mining and high temperature and humidity. Although temperature and atmospheric pressure alone may not be contributing factors in the incidence of silicosis, the few mining companies who operate under the extremes of these conditions are dust conscious and keep dust-control engineers on their operating staffs.

Jan 1, 1961

By J. W. Horne, W. B. Shirey

"INTRODUCTION The United States Bureau of Mines in cooperation with the State of Colorado at the University of Colorado has conducted experiments to determine the amount and composition of the noncondensable gases evolved when crude shale oil is distilled under pressure.Hydrogen sulphide is one of the components found in the complex mixture of gases produced by the distillation of shale oil under pressure. This paper deals with the apparatus and method used in determining the amount of hydrogen sulphide evolved in the laboratory experimental cracking stills.The study required a complete extraction of all the hydrogen sulphide from the gas stream after it left the water-cooled distillate condensers and before the as stream entered the charcoal absorber for removing the light naphtha. In devising the method it was necessary to take into account a constant variation of velocity, pressure, and percentage of sulphide in the total gas stream coming from the still.Ordinarily, the quantitative determination of hydrogen sulphide in Gas is made by analyzing small samples taken at regular intervals. This estimation can be accomplished by use of the Bunte gas burette as modified by Tutriler,4 or by a similar method. In the industries where the flow of as is constant end of uniform composition, this practice is sufficiently accurate for plant control. For experimental work where many variables have to be taken into consideration, as in the case at hand, these methods are not applicable."

Oct 1, 1931

By Christopher C. Jobes

This U.S. Bureau of Mines report describes a system to determine the position and heading of a mining machine during maneuvers in the face area of an operating mine section. The system is the first step in the development of a guidance system for automated mining machines. The position and heading algorithm is described, and a preliminary error analysis is performed. The sensors employed were linear position transducers mounted on a mining machine with their cables attached to points on a stationary reference. Four linear position transducers were used to provide a data redundancy that increased the reliability of the guidance system. The linear position information obtained from the transducers was processed mathematically via the position and heading algorithm to provide the desired position and heading information. The algorithm takes advantage of sensor redundancy to continually test the accuracy of the sensor data. The major sources of error were determined to be the linear position transducers, the analog-to-digital (A/D) converter used to interpret the data, and the sampling frequency of the measurement system. These sources of error were evaluated to determine their inaccuracies for use in calculating the overall system accuracy.

Jan 1, 1990