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By L. C. IlsLey

"Nearly every piece of electrical equipment used in mines ""breathes."" In other words, motors, controllers, rheostats, switches, and other similar equipment, even though encased in seemingly tight compartments, breathe in the atmosphere that surrounds them.As the apparatus is used, the temperature of metallic parts is changed generally in positive direction through the heat by friction and the heat due to the electric current. When the apparatus is idle it gradually cools down to the temperature of the surrounding atmosphere.This increase of temperature during operation and return to normal temperature when operation stops alternately raises and lowers the temperature of the atmosphere within the compartments which, in strict accordance with Charles' law -will expand or contract in proportion to any given temperature change.As compartments are not gas-tight, such expansion and contraction will force the atmosphere out of the compartment =on expansion and suck the surround¬ing atmosphere into the compartment during contraction, hence the term ""breathing.""Investigators2 of explosion-proof equipment have recognized that such an interchange would take place and have designed their equipment to safeguard possible explosions within the compartments."

Jun 1, 1927

By M. F. Dunn

During a mine fire or other emergency, it may be desirable to reverse the airflow in order to provide an escapeway or to isolate a fire. Also, in colder areas, the airflow may be reversed to prevent ice buildup. When reversing main mine fans, the mine operator usually does not know what operating characteristics of flow and pressure to expect. Laboratory and field tests of vane axial main mine fans in the 7- to 9-ft diameter size range were conducted to establish forward and reverse performance characteristics under controlled conditions and at typical mine installations. The data obtained suggest that reverse performance characteristics are dependent upon the blade angle and the hub to tip ratio. There is also evidence that reverse performance can be predicted for a family of blade angles and a given hub to tip ratio. Generally, quantity of air is 30 to 65% less in reverse than when operating in the normal forward mode.

Jan 1, 1983

By Xinquan Zhou, Rudolf E. Greuer

MFIRE, written in Fortran 77, is a computer program for ventilation state simulation in the steady state or transient state condition. It can be applied for the calculation of normal ventilation system planning or the analysis of the dynamic state variation in a ventilation system under thermal or mechanical disturbance. The state simulator MFIRE is a useful tool for mine fire fighting. In the case of a mine fire, mine ventilation engineers want to get some help to obtain more information, such as what is happening in the underground mine and how to control the mine fire, for correct decision making. By use of program MF'IRE, forecasts can be made on the variation of airflow, temperature, and contaminant distribution in a ventilation system during a mine fire. The paths which the contaminant takes at each time interval can be traced. The program MFIRE can be of assistance in the preplanning of escape routes. It can also be helpful during a mine fire emergency and mine recovery operation. Besides of offering the information of state simulation during a mine fire, MFIRE can be applied for state control by pretesting the suitability of the selected state control measures. It is to simulate the effects of the state control measures on the airflow distribution of a dynamic ventilation system. The testing result can be used for fire fighting in a similar real case of a mine fire. By employing empirical methods or a qualitative analysis like Budryk approach, ventilation engineers can choose different combinations of locations and sizes of control devices as samples of state control for an underground mine fire. Program MFIRE can simulate the different combination samples, that consist of a certain mine fue, the corresponding different control measures, and obtain the control effects. After the different control results are compared, the state control measure, which creates the best effect among the different state control measures, will be chosen for that fire case. When a mine fire, which is similar to one of the pretested cases, breaks out, the corresponding choice of the state control measure is applied to the ventilation system. It means that the simulator MFIRE has the function of indirect state control [10]. To achieve the above two functions, state simulation and state control, the mine ventilation system condition, sometimes, should be changed in a wide range to meet the requirement of the fire fighting. These wide system condition changes, such as adding operating fans, stopping or reversing fans, changing fan characteristics, adding regulators and making airflow shortcuts are represented in the time table of the input data set When the data files are changed in a wide range, however, an iteration divergence and some other computing errors in the distribution of airflow, temperature, and contaminant may occur. More serious logical programming and flexible selection on the algorithms are wanted to meet the request of the different data sets, to achieve correct state distribution simulation and improve the iteration convergence. To enhance the reliability and common suitability of program MFIRE, it is necessary to make investigation, analysis, and modification for the formal versions of MFIRE. The version 1.29, permitting dry .calculation, and versions 2.01/v2.0, permitting dry and humidity calculation, are widely applied

By H. E. Powell

This study was made to determine the capabilities and limitations of the hydrocyclone for separating quartz sand from impure clays, Optimum operating conditions for beneficiating typical subgrade clays were determined. Estimates are furnished for installation and direct operating costs of hydrocyclones in such separations. Laboratory models of commercial hydrocyclones were used to beneficiate a suite of fire clays including plastic, semiflint, and flint types, all of which were contaminated with quartz in amounts ranging from 3 to more than 62 percent. Results show that this technique is not limited to a single type of clay but is applicable to clays ranging from plastic through flint, Under proper conditions use of this technique will result in good separation of the sand and good recovery of a useful clay mineral concentrate. Rejection of quartz from the clays investigated ranged from a low of 82.4 percent with an alumina recovery of 71.2 percent to a high of 99.0 percent with an alumina recovery of 85.6 percent.

Jan 1, 1963

By G. W. Elger

This report describes pilot-plant studies and an economic evaluation of a process developed by the Federal Bureau of Mines, Albany Metallurgy Research Center, to produce synthetic rutile from a rock-type ilmenite concentrate. In this process, ilmenite blended with coke and lime is smelted in an electric arc furnace to separate most of the iron as salable pig iron and to form a titania-enriched slag of low iron content, which is treated with oxygen and titanium pyrophosphate. The titanium oxides are converted to crystalline rutile; the phosphate glass contains most of the associated impurities. The treated slag is ground and leached with sulfuric acid to liberate rutile crystals, which are concentrated by physical methods. In pilot testing conducted to obtain data for a cost estimation, a synthesized product containing about 88 wt-pct TiO2 and less than 2 pct FeO was extracted from a rock-type ilmenite concentrate containing about 45 wt-pct TiO2. The estimated fixed capital cost (on a mid-1975 basis) of a plant producing 500 tpd of synthetic rutile is $28,290,100. Based on 330 operating days per year, the estimated operating cost for this process is $351 per ton of synthetic rutile. The estimated selling price of synthetic rutile made from rock-type ilmenite is $344 per ton, based on a credit of $160 per ton of pig iron and a 20 pct interest rate of return on investment after taxes.

Jan 1, 1976

By D. Harrington

The record of fatalities from mine explosions in the United States during the fiscal years 1934 to 1937 wars the best in the history of the mining industry; that for the fiscal year 1939, however, is not so favorable, since nearly as many men (170) were killed by explosions in 1938 as were killed during all of the previous 4 years (182). In spite of the large increase in fatalities from explosions during 1938, the average for the past 5 year period (70.4) is less than one-half the average (13) of the preceding 5 year period. The reasons for the large increase in the number of explosion fatalities during the 7 past year as compared with the previous 4 year are not entirely clear; it is: evident, however, that in some instances there has been laxity in the enforcement of State minim laws, and also that come of our coal-mining people, including workers and operating officials, have failed to carry out tine known precautionary measures to prevent explosions.

Jan 1, 1939

By H. A. Doerner

From thermodynamic calculations3 Maier predicted that zinc oxide Land methane would react at specified temperatures substantially according to equation (1). (1) ZnO + CH; = Zn (gas) + CO + 2H2 Other reactions that may take place are: (2) CH4 = C + 2H2. (3) ZnO + CO = Zn (gas) + CO2 (4) ZnO + H 2 = Zn (gas) + H2O . Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1), at equilibrium, would be substantially complete at or above 927°C.

Jan 1, 1931

By Warren E. Morrison

This study was prepared in response to the need for a series of data that reflect the basic flow pattern of energy resources in the United States. To effectively measure and analyze energy,2 it is necessary to prepare balances that reflect both production and consumption, and the various forms energy resources take at different stages of utilization. Before energy can be measured it must also be put into a common unit. In this study the common unit used is the British Thermal Unit (Btu). The ideal point to survey energy is at the stage of final ultimate use, representing the useful work derived from the interaction of energy inputs and the prime mover. Unfortunately this concept of efficient or useful work from energy output cannot readily be measured in the aggregate. With the present available official data, energy measurement can be carried to the point of calculation of net inputs of energy3 into the economy at various stages of utilization. However, preparation of energy balances, on a net basis is hampered by the fact that this can only be done for years when the censuses of Mineral Industries and Manufactures are taken, usually at 5-year interval.

Jan 1, 1964

By G. W. Reimers

Conditions in the underground mine environment can cause self-heating of sulfide ores as a result of exothermic oxidation reactions, which may result in mine fires. This Bureau of Mines report describes thermal analyses of finely ground chalcopyrite, chalcocite, galena, pyrrhotite, marcasite, and arsenopyrite, to characterize their responses under oxidizing conditions. Thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) were used, in the temperature range 1000 to 5000 C. Chalcopyrite showed an initial weight gain, due to formation of sul-fates, a weight loss, caused by ignition of iron sulfide to iron oxide, and a final weight gain, indicating the conversion of copper sulfide to sulfate. Chalcocite did not ignite in the temperature range studied but exhibited a rapid weight gain, because of the rapid conversion of copper sulfide to sulfate. Likewise, galena failed to ignite but underwent a steady weight gain when oxidized in a moist atmosphere, showing conver-sion of lead sulfide to sulfate below the ignition point. Marcasite underwent a rapid weight loss, indicating ignition, at 2000 C. Moisture in the oxidizing atmosphere lowered the ignition point of marcasite and arsenopyrite but not that of pyrrhotite. All the sulfides exhibited exothermic behavior at temperatures below the ignition point.

Jan 1, 1987

By T. E. Gray

This report describes the preparation characteristics of the more significant coalbeds in Butler County, Pa. It is one of a series planned to determine which coals are suitable for producing metallurgical coke, either as mined or after beneficiation. More than 2 million tons of coal was produced in Butler County in 1958, of which about 25 percent was cleaned mechanically in four cleaning plants. Updating the 1942 coal-reserve estimates made by Ashley to December 31, 1958, more than 1,266 million tons of recoverable coal reserves remain in the county in beds that arc 24 inches or more thick. The Upper and Lower Freeport, Upper, Middle, and Lower Kittanning, Clarion, and Brookville beds were selected on the basis of production and estimated minable reserves. Sample locations were chosen after a study of the literature, conferences with mining engineers and mining company officials in the field, and examination of the available sites. Four samples each were collected from the Upper Freeport and Middle Kittanning beds, three samples from the Brookville bed, two, samples from the Upper Kittanning bed, and one sample each from the Lower Freeport, Lower Kittanning, and Clarion beds.

Jan 1, 1960

By T. J. Williams

Researchers at the U.S. Bureau of Mines monitored rock mass response to mining of an experimental underhand longwall stope in Hecla Mining Co.'s LUCKY Friday Mine, Mullan, ID. This stope design, the Lucky Friday underhand longwall (LFUL), was proposed as a means of controlling rock bursting while also allowing increased mechanization of mining operations. Instruments were specifically manufactured to monitor three geomechanical factors (backfill performance, ramp stability, and rock mass response) that directly affect the success of stope design. Despite considerable difficulties with instrument installation and survival in the harsh mine environment, especially within the stope fill, sufficient information was collected to suggest that the LFUL method was successful in achieving project goals. This conclusion, in addition to favorable economic and operational evidence, led the mine to adopt the method throughout the mine. Indeed, this study and mining experience suggest that underhand longwall mining could be considered a feasible mining method for rock-burst-prone ground throughout the Coeur d'Alene District. Further Reports of Investigations (RI) in this series present in-depth analyses of the effects of backfill on rock bursting and calibration of a stope numerical model.

Jan 1, 2010

By H. R. Babitzke, H. Kato, R. E. Siemens, G. Asai

The purpose of this investigation was to develop a wide variety of columbium and tantalum alloys and to determine their suitability for use at elevated temperatures . Sixty - nine columbium and tantalum alloys were investigated . For this study , columbium was alloyed with two or more of the following : nium, tungsten , vanadium , titanium, and zirconium . Tantalum was alloyed with vanadium or hafnium, or hafnium and carbon . The fabricability was determined by an arbitrary procedure . Hardness measurements , elevated - temperature tensile properties , and oxidation- resistance studies were made . Of the alloys studied , Cb - 15 Hf - 5W, Cb - 15Hf - 5W- 10Ti , Cb - 15Hf - 10W- 10Ti , Cb - 10V - 5W, Ta - 30V , and Ta - 20 to 33Hf exhibited excellent high - temperature properties . These alloys were not only easy to fabricate , but they also had good oxidation resistance and excellent high- temperature strength .

Jan 1, 1964

By D. J. Dollhopf

An overburden handling dragline operation was conducted at a strip mine near Colstrip, Montana. The objective of the demonstration was to determine the degree a dragline could mix overburden inhibitory zones during the spoiling process. In order to quantify the mixing process the overburden was: 1) scatter spoiled; 2) dump spoiled; and 3) spoiled in a normal manner. This demonstration was part of an effort to investigate means of reestablishing non-polluted hydrological systems in areas where surface mining directly impacts shallow ground-water resources. When inhibitory material constituted < 5% of the total overburden volume, such material was essentially not detectable in the resultant spoil pile. When inhibitory material exceeded 15% of the overburden volume it was always found in the resultant spoil pile, generally with a smaller extent, indicating partial dilution. Inhibitory overburden zones often reappeared at the base or top of spoil piles in the potential aquifer and root zones suggesting the need for selective placement procedures. Scatter spoiling did not appear to be significantly more effective than normal spoiling, however clump spoiling seemed to produce less mixing of inimical zones. Mining activity has reduced ground-water levels within 1600 m of the active pit. The aquifer which is developing in spoils appears to have similar confinement characteristics as those that existed in the premined aquifer. To date no definite trends have been observed concerning changes in surface or ground-water chemistry associated with mining.

Jan 1, 1978

By Michael G. Zabetakis, Aldo L. Furno, Henry E. Perlee

The Bureau of Mines conducted an experimental study with liquid and gaseous hydrogen to determine the hazards associated with the use of liquid hydrogen as an ionizing particle detector in bubble chambers . The glass window , the vacuum chamber , and the vent system were investigated . In addition , a study was made of the detection and ignition of escaping hydrogen and of the available electrical equipment for use in hydrogen atmospheres . Materials such as tempered glass , aluminum , and stainless steel are not penetrated readily by the small fragments formed when fully tempered glass is shattered and propelled by hydrogen at initial pressures up to 100 psig ; long , slender fragments from untempered glass may penetrate thin walls of relatively soft materials such as rubber gaskets and lead . Hydrogen can be vented satisfactorily from a vacuum chamber with a well - designed vent system . However , the rapid leakage of hydrogen into the surrounding air is a serious problem because the available detectors are satisfactory only when the accumulation of hydrogen is slow . Much of the electrical equipment currently available was designed for use in hydrogen- air atmospheres .

Jan 1, 1963

A Helix Pressure Gauge to Indicate roof bolt loads was designed, fabricated and field tested. The gauge indicated loads between 3,000 and 15,000 pounds with a ± ten per cent error. The coat of fabrication of the gauge was estimated to be $3.39 including an assumed overhead and profit per indicator for a series production of 5,000 unite. The unit can be read on a bolt to within ± 1,000 pounds load from a distance of twenty feet.

Jan 1, 1974

By Richard D. Miller

The helium resources base of the United States was estimated by the Bureau of Mines to be 1,040 Bcf as of January 1, 1987. These resources are divided into four categories in decreasing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 265 Bcf, (2) helium in probable natural gas resources, estimated at 228 Bcf, (3) helium in possible natural gas resources, estimated to be 320 Bcf, and (4) helium in speculative natural gas resources, 227 Bcf. These helium resources are further divided into depleting and nondepleting, with the helium in storage being in a separate classification. The depleting resources are those associated with natural gasfields that are, or will be, produced for the natural gas they contain. Almost all of the helium in potential (probable, possible, and speculative) natural gas resources is included in this classification. These depleting resources are estimated to contain 951 Bcf of the total helium resource base. Helium resources contained in nondepleting natural gas resources, i.e., those in shut-in, abandoned, or otherwise nonproducing natural gasfields, are estimated to total 53 Bef. There is 36 Bcf of helium in storage in the Federal Government-owned Cliffside Gasfield near Amarillo, TX.

Jan 1, 1988

By Bernard Baum

Combined preservative/fire retardant systems were pressure impregnated into Douglas fir and Ponderosa pine samples and evaluated for decay, flammability, and mechanical properties. The objective of the evaluation was to identify cost-effective systems for use with mine timber, and to provide an information and data base from which Federal code regulations could be established. Thirty systems, based on combinations of commercially available preservatives and fire retardant impregnants and coatings, were applied to Douglas fir samples and evaluated for decay and flammability. The ten most promising systems were ap¬plied to both fir and pine and reevaluated for decay and flammability before and after water leaching. The five best systems were given a thorough laboratory evaluation using both pine and fir. Evaluations included flame spread, smoke density, toxic gases, decay, compressive strength, flammability after artificial weathering, and cost. All systems had acceptable toxic gas levels and smoke densities, but flame spread was only borderline acceptable for most of the samples tested. A trade-off analysis showed Acid Copper Chromate/Fyrprufe with Albi-107A/144 intumescent paint and Koppers NCX to be the-best systems. Recommendations are made for further large-scale testing using the two best Systems.

Jan 1, 1978

By Walter E. Lewis

A mothod of cutting St. Poter sandstono by streams of water under pressuro from nozzles and pumping the resulting, sand to the surface has roduced the cost of storm-sowor construction in the Minneapolis-St. Paul aroa. The hydraulic tunneling method, has boon in uso since 1934, and it is adaptable only to the lower part of tho St. Potor, sandstone, which lios within or just abovo the ground-wator levol. Tho upper part of the formation, immediately bolow tho Plattoville limestone, 18 comonted and camot bo mined by hydraulic mothods. The tunnel oporation observed in this instance is a main storm sowor starting at tho Mississippi Rivor below the 10th Avenuo SE bridge and will be drivon 6,000 foot at a grado of 1 foot por thousand undor the city of Minneapolis to Konnody and Arthur Stroots NE. A lateral storm sowor, which branchos from the main sovor at 8th Street SE, will oxtond from 10th Avonuo SE to 15th Avonuc SE. Tho tunnele are being drivon with the floor approximately at ground-wator lovol. All waters ontoring the main storm sower vill drain into the Mississippi Rivor. Tho main storm sewer cross soction is excavated to a roughly hox- agonal shapo 10 foot high by 10 foot wido at the contor. The upper half of the tunnol soction is solidly lined with either timber or stool. After all oxcavation is completed, the tunnel will be finished with a concrete circular lining 8 feet in inside diameter. The lateral storm sewer is excavated to a 5-1/2-foot by 7-1/2-foot section and will event- ually be finished with concrete to a modified horseshoe-shaped section 6 feet by 4 feet. Where the back or walls are considered unsafe during excavation, the upper half of the tunnel is lined solidly with timber. The equipment used by the Sower Division, City of Minneapolis, has been selected to meet a number of applications in storm-sewer work with diversified usage in mind. The sand pumps used on this job are rubber-lined, designed to work against a head of 100 foet. Either 4-inch or 6-inch diameter suction and discharge openings may be used. Other equipment, such as pipe, mine rail, flexible hoses, compressors, and general surface shop equipment, is drawn from a contral warohouse. It may be either new or used, depending on what is available at the warehouse. Much of the pipe and mine rail has been used for many years on several different tunnol jobs.

Jul 1, 1950

By R. V. Higgins

This report presents the results of a study of water injection in the HX sub-pool fault block V-B, in the Upper Terminal zone, Wilmington field, California, and is based on data obtained to May 1957. An earlier report3/ describes the results of gas injection in part of the field. The principal purpose of the pilot flood was to determine whether a sand having a permeability of 1,200 millidarcys and containing oil having a viscosity of 17 centipoises could be waterflooded effectively. The results of a preliminary study by engineers of the Long Beach Harbor Department of oil recoveries from areas where encroaching edgewater was active and the results of an independent study by a consultant retained by the Long Beach Harbor Department were favorable to a trial waterflood. After these preliminary studies, a detailed petroleum-engineering exam-ination was made of the technical details. As a result, a peripheral flood was started in June 1953. The peripheral flood was deemed desirable because the producing wells are bottomed a short distance from the edgewater. The HX subpool was selected for the pilot test because it is an isolated section of the Upper Terminal zone and is separated from the adjoining pools by faults on the east and west and by edgewater on the north, south, and west. Several petroleum-engineering methods were applied to evaluate the performance of the waterflood, and all showed that injecting water stimulated oil production.

Jan 1, 1958

By W. W. Adams

"The fifth annual National Safety Competition conducted by the United States Bureau of Mines to determine the best safety records at mines and quarries during the calendar year 1929 has been concluded, and the general results of the contest are presented herewith. To the winner in each of the five groups into which the contestants were divided there has been awarded the bronze trophy 'Sentinels of. Safety,' donated by the Explosives Engineer magazine. The trophy for bituminous coal mines was won by a mine in Alabama; that for metal mines by an iron-ore mine in Michigan; that for nonmetallic mineral mines by a salt mine in New York; that for quarries and open-cut mines went to a limestone quarry in Michigan;. the trophy provided for anthracite mines was, of course, won by a mine in Pennsylvania, as all of the anthracite mines participating in the contest are situated in that State.Winners of the trophies were selected by a committee of sward in accordance with rules governing the contest and on the basis of accident records furnished by the various companies to the Bureau of Mines. These records were summarized by the bureau and the results submitted to the committee. Members of the committee are W. H. Cameron, managing director of the National Safety Council. William Green, president of the American Federation of Labor; James F. Callbreath, secretary of the American Mining Congress; T. T. Read, Vinton professor of mining of Columbia University and editor of 'Mining and Metallurgy'; C. B. Huntress, executive secretary of the National Coal Association; A. J., Curtis, assistant to the general manager of the Portland Cement Association; A. T. Goldbeck, director of the engineering bureau of the National Crushed Stone Association.Thirty-four States were represented in the l29 contest. Among the plants which participated were 68 bituminous coal mines, 29 anthracite mines, 54 metal mines, 19 nonmetallic mineral mines, all of the foregoing being underground mines, and 141 quarries or open-cut mines. A total of 106,533,006 man-hours of work was reported by all of the companies. Accidents during the year numbered 7,008 and represented a period of disability equal to 986,306 man-days. Hence the accident-severity rate for all plants combined represented 9.3 man-days of disability for each thousand man-hours of exposure to hazard. Similarly, the combined accident-frequency rate for all plants showed that 66.3 accidents occurred for every million man-hours of exposure to hazard. Both of these rates indicated an improvement over the combined rates for all plants in the previous year's contest. The reduction in the accident-severity rate centered chiefly in the metal mine group, though all except the quarry and open-cut mine group shared in the reduction; the improvement in the accident-frequency rate was in all croups except anthracite and metal, the rate for the former having increased while that of the latter remained unchanged."

May 1, 1930