Search Documents

By Robert A. Cortese, Henry E. Perlee

Coal dust and float coal dust, produced during normal mining operations, in underground coal mines, are carried from the point of origin downstream by the ventilating air, where it deposits on the surfaces of the mine entry. In an explosion, this dust is lifted from the surfaces by the aerodynamic disturbances and, if of sufficient quantity, can continue to propagate the explosion. To prevent the surface coal dust from contributing, it must be inerted, typically by spreading pulverized limestone, i.e., rock dust, over the coal dust surface. To facilitate the dusting operation, the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory(PRL), developed an automated system that continuously monitors the accumulation of coal dust. This system could activate a rock-dusting machine that disperses rock dust into the ventilation air when dangerous deposits accumulate and deactivate the machine when sufficient inert has been deposited on top of the coal dust. The system consists of a microprocessor-controlled optical float dust deposition meter. This device measures the light intensity reflected from a deposited layer of dust. A standard cap lamp is used as a fixed-position light source. From the reflected light signal, the microprocessor determines the hazard level of the deposited layer and performs the appropriate action. Full-scale studies conducted in the Experimental Mine at PRL's Lake Lynn Laboratory, using alternating thin layers of rock dust and coal dust, successfully demonstrated the operation of the device. Based on the statistical data from these studies, a mathematical model was developed to predict long-term error in total rock dust content using this inerting procedure. Downwind dust dispersion was also examined to provide optimum placement of the dust sensors and to determine the need for better rock dust dispersion techniques.

Jan 5, 1998

By Alan D. Hartman

Standard metering of electric arc furnaces usually uses root mean square (RMS) or true root mean square (TRMS) measurements for determining power. Only sinusoidal signals are accurately described by RMS meters, and dc or high-frequency components normally are lost in standard TRMS metering. This can lead to inaccuracies when electrical signals are not sinusoidal, contain dc components, or include fast risetime perturbations, as is the case with the electric signals from an electric arc furnace. Electric arc furnace electrical waveforms, observed in research carried out by the U.S. Bureau of Mines, show high-frequency components and significant deviations from sinusoids. These perturbations and distortions make metering difficult for standard power meters. The inaccuracies in metering can cause further problems if those sensors are used in control systems. For control strategies requiring rapid response, any averaging scheme loses information that can be used in control decisions. In order to obtain better signals for both monitoring and control, a study of instantaneous, RMS, and TRMS power monitoring devices was conducted. From this study it was concluded that precision integrated circuits should be used to obtain instantaneous power with a bandwidth of at least 25 kHz. The information from these devices is more representative than that of standard meters and can be used in predictive control.

Jan 1, 2010

By Paul J. Guay

This report presents the results of evaluating a longwall mining system specifically designed to extract a very deep web (60 inches or deeper) from a longwall panel. The report includes a productivity and cost analysis comparing the new mining sys-tem with a high capacity conventional longwall operation taking a 30-inch wide web. The analysis shows the new system will increase annual production 44 percent and decrease cost per ton off the face 21 percent. The report also includes conceptual drawings and specifications for a high capacity four-drum shearer and a unique shield type of roof support specifically designed for very wide web operation. The advantages and problems associated with wide web mining are discussed in general and as they relate specifically to the equipment selected for the new mining system. The study concludes by recommending that surface coal loading tests be conducted as the follow-on work.

Jan 1, 1978

By W. P. Huleatt, R. B. McCulloch

"The Big Four zinc-deposit, directly above the north bank of the Green Mountain Reservoir on the Blue River, Summit County, Cole., was discovered in 1937 by the present owner, Walter McDaniel, who lives on the property. Mr. McDaniel, together with members of his family, have worked the mine on a small scale since its beginning and have shipped quantities of sorted high-grade ore to the International Smelting Co. at Tooele, Utah, and the Combined Metals Corp. at Bauer, Utah. More recently, parts of the nine have been operated by lessees.The property had been examined previously by the Federal Geological Survey, and the geological report was made available' to the Bureau of Mines.The Big Four mining claim was located in 1937 by Walter McDaniel and his wife Frances,- who had been prospecting in the vicinity since 1933. The discovery of the high-grade zinc deposit caused considerable excitement, as it had not been regarded as a mineralized area.Mining was begun in 1937 and carried on until 1944 by Mr. and Mrs. McDaniel with the help of a few hired miners. During 1944, parts of the mine were leased: to various parties Who produced small quantities of ore but did no development work.Shipments during 1941 .totaled 752 tons; during 1942, 387 tons; and during 1943, 510 tons. From the beginning of 1944 to April of that year, 98 tons wore produced and shipped to Utah,Since the lessees began operations, a grade of 30 to 35 percent zinc has been maintained by careful sorting. No production has been recorded for 1945.The Big Four mine is situated on Colorado State- Highway 9 between Dillon and Kremmling on the south face of Green Mountain overlooking the Green Mountain Reservoir, a Federal irrigation project on the Hue River, Green Mountain rises 1,600 feet above the general level of the valley to an altitude of 9,408 feet and the surrounding terrain, i s correspondingly mountainous and rugged."

Apr 1, 1946

By Robert C. Merritt

This report describes laboratory as well as pilot heap leaching investigations of low-grade sandstone ores from Wyoming, New Mexico, and Colorado. Sodium carbonate-bicarbonate solutions containing sodium hypochlorite extracted up to 86, 54, and 16 percent U308 from Wyoming, New Mexico, and Colorado ores, respectively. Ammonium carbonate-bicarbonate solutions containing sodium hypochlorite were less effective at leaching these ores. Acid leach in replicate pilot plant testing resulted in U308 extractions of 96, 88, and 81 percent from the Wyoming, New Mexico, and Colorado ores. The development of cost-effective processes for extracting uranium from low-grade ore is essential to the assurance of a continuing domestic supply of uranium.

Jan 1, 1977

By Michael R. Kennedy

This report describes the demonstration of longwall mining in a seam dipping 27 to 34'. Equipment was selected on the basis of capability, compatibility, and co t. Snowmass, Bureau of Mines, consultants and manufacturers were involved in the selection process. The equipment arrived in early 1981, prior to completion of development for the first panel; therefore, the equipment was operated on the surface for training. The surface training paid off with a fast, efficient installation and start-up of the face. The longwall equipment operated very well on the steep pitch with an average equipment downtime of 21.9[9]. Coal handling outby the face was a problem which caused an additional downtime of 19.5%. Development for the panels proved to be the major problem in the economics of longwall mining on a steeply dipping seam. During the first 9 months of operation the longwall averaged 71.9 TPMS and development averaged 0.6 TPMS for an overall average of 14.1 TPMS. Had mining continued, timing of development would have been another major problem. Monitoring of subsidence, pillar stability and shield loading was done in connection with mining, but little useful information was gained from the monitoring.

Jan 1, 1987

Auger operations produced 14 million tons of coal in 1974, or approximately 5% of all surface mined coal. It was the most efficient of all coal mining methods, producing 40.0 tons per man-day. Exhibit 1.1 gives a breakdown of productivity of all coal mining methods. Exhibit 161 PRODUCTIVITY OF COAL MINING METHODS (Short tons per man-day) [Method - 1971 1972 1973 1974 Conventional 11.00 10.00 9.75 9.30 Continuous 13.00 12.50 12.25 11.90 Strip Mines 35.69 35.95 36.00 36.00 Auger Mines 39.00 43.00 45.33 40.00 ] Unlike other surface mining methods, augering produces clean coal, largely uncontaminated by foreign materials, other than those existing in the coal seam itself. However, compared to other methods, the coal recovery rate is relatively low. For example, a triple-headed auger in a 35-inch seam would recover approximately 50% of the coal in the seam as compared to a 90 to 95% recovery rate for strip mining and a 55 to 65% recovery rate for deep-mining. The low auger recovery rate is due to the circular cuts and pillars left in the seam.

Jan 1, 1975

By Harry W. Campbell

A Bureau of Mines investigation identified no mineral deposits in the Lost Creek RARE II area. Sand and gravel has been mined from alluvial flood plain deposits just outside the RARE II boundary. An oil and gas lease application which includes the eastern portion of the RARE II area is pending. Abundant basalt in the area can be crushed and used as aggregate; but it could not compete with similar deposits in more favorable locations, or with cheaper substitutes such as volcanic cinders or sand and gravel which are available outside the study area closer to major markets. No indication of coal or geothermal energy resources was found. INTRODUCTION Location and Access The Lost Creek RARE II area encompasses 8,300 acres (3,400 ha) of Lassen National Forest in north-central California, about 20 mi (30 km) north of Lassen Peak. The closest city is Redding, California, 50 air mi (80 km) southwest. Peripheral access is provided by State Highway 89 passing near the western RARE II boundary (fig. 1). The Pacific Crest Trail traverses the western margin of Hat Creek Rim adjacent to the eastern boundary of the area.

Jan 1, 1983

By Bertrand L. Johnson

The major elements essential to plant growth are nitrogen, potassium, and phosphorus. These three constituents of the soil are removed relatively rapidly by growing crops and consequently are the main constituents of commercial fertilizers. Scientific studies, however, have progressively revealed the fact that a number of other plant foods, many of which are not necessarily supplied in commercial fertilizers, are necessary to assist plant growth and fruit production and that soils deficient in certain of these minor elements may be made much more productive by adding them. The farmer looks to the miner to furnish most of the elements requisite to plant growth, which have to be supplied through the medium of fertilizer additions. It follows that the mining industry should keep an eye upon developments in the fertilizer industry and in the results of soil studies as a possible outlet for mineral products. The important industries engaged in the production and marketing of the three principal pant nutrients have already been described in Bureau of Mines publications .3 The present paper discusses the commercial implications with respect to other elements that are now employed as soil additions.

Jan 1, 1935

By E. D. Gardner

Open-cut mining of copper ores in the western United States is a relatively new industry. At first the mining methods were mainly adapted from those used at open-cut iron mines and at quarries, but now efficient practices that are more suitable for the copper deposits have been developed. The pioneer in this field is the Utah Copper Co., of Bingham, Utah, which deserves great credit for working out much of the early procedure. Stripping began at that mine in 1906, and the large Garfield concentrator was put in commission in 1908. Next in order of development were the Nevada Consolidated Copper Co., at Ely, Nev. ; the Chino mine of the Ray Consolidated Copper Co., at Santa Rita, N. Mex. ; the New Cornelia Copper Co., at Ajo, Ariz. ; the Sacramento Hill mine of the Copper Queen Branch, Phelps Dodge Corporation, at Bisbee, Ariz.; and the open cut of the United Verde Copper Co., at Jerome, Ariz. The Sacramento Hill mine began to produce in 1923, and the United Verde open-cut mine has produced ore mainly in connection with stripping. The writer visited the Utah Copper mine in September, 1923; the Nevada Consolidated in August, 1923; the Chino in July, 1924; and the New Cornelia, the Sacramento Hill, and the United Verde open cut at various times during 1922, 1923, 1924, and 1925, mostly in connection with other work.

Jan 1, 1927

By R. B. Crookston

Oil shales differ from coals in that they contain less carbonaceous material, convertible to volatile hydrocarbons, and more inorganic rock. In all pre-commercial oil shale development, involving extensive full scale mining operations, there have been no explosions. However, large scale mine tests with oil shale dusts by the Bureau of fines showed that propagating explosions could be induced under certain circumstances. Laboratory tests were conducted on a broad spectrum of oil shale dusts to define chemical properties and to seek correlations with subsequently determined fire and explosivity properties. These latter properties, indicative of safety hazards, increased as the Fischer assay oil yield of the dusts increased and as particle size decreased. Laboratory data were used to relate fire and explosivity properties of oil shales to those of coals and other carbonaceous materials and to assist in the identification and evaluation of potential hazardous situations which may be encountered in oil shale mining and processing.

Jan 1, 1978

By Piyush K. Dutta

This report describes the design, development and manufacture of production stoper drills and results of their field tests, it is shown that underground stoper drill noise level can be reduced from 118 dBA to below 100 dBA by using these pneumatic drills. The design concept of these drills is a radical departure from the standard valved rifle bar type drill machine design to a drill featuring a valveless independent rotation system, use of an integral muffler and a shroud tube. Six drills were manufactured in a standard commercial drill manufacturing setup and organization. The design and production technology proved that commercially viable quiet drills can be made available for mine use.

Jan 1, 1983

By James E. Hill

Tremendous improvements in mining technology have been witnessed during the past 100 years. For example, before 1860 all blastholes were drilled manually and blasting was done with low-energy black-powder. During the 1860's both the pneumatic rock drill and high-energy dynamite were introduced, ushering in an era of mining mechanization that has steadily progressed since that time. Today, with the rapid implementation of the latest advances in communication science, mining technology is moving into a new era that goes beyond mechanization as such. Transistors, transducers, scanners, telemetry, and the like, all terms largely derived from the new communication sciences, add up to what is popularly know as automation-the communication of machine with machine. Automation is now playing an important role in selected parts of the mining process, such as hoisting, hydraulic roof supports, and underground surface locomotive haulage and belt conveyor systems. But this year marked the first attempt to auto-mate the total mining process with the commencement of production at the British National Coal Boards Bevercotes mine. If this full-scale experiment proves successful, it could lead towards other fully automated mines in both Britain and other parts of the world. This decade, there-fore, could be considered the one that provided the foundation for the mines of the future.

Jan 1, 1966

By Edmund Newton

The Haile mine has been the outstanding gold-mining operation and the largest single producer of gold in the Appalachian region. Gold was discovered at the Haile in 1827, previous to the present operation, production has been nearly $4,500,000 (gold at $20.67 per ounce.) from somewhat over a million tons of ore, with an average extraction of about 70 percent. The Haile property, now operated by Haile Gold Mines, Inc., is in the southern part of Lancaster County, South Carolina, 3-1/2 miles northeast of the town of Kershaw and 55 miles north of Columbia, the State capital. (See fig. 1.) The corporation has a lease and purchase contract on 1,805 acres, covering the present productive area. In addition, it holds lease contracts on 1,500 acres additional adjacent to this area.

Jan 1, 1940

By Robert K. Guthrie, James W. Amyx, D. B. Taliaferro

"INTRODUCTION Secondary recovery of oil by water-flooding is practiced more extensively in North Texas than in any other section of the State, and the progress and experience of the operations in that area are of continuing interest to all branches of the oil industry. The first Bureau of Mines report on water flooding in North Texas 7/ chronicled the activities from December 7, 193f', when the Railroad Commission of Texas granted The Texas Co. the first permit to inject water into an oil-bearing sand, through 1944. This second report has been prepared as a supplement to Report of Investigations 3906 to show the progress and expansion of water-flooding. The format of this report is almost identical with what of report of Investigations 3906, except for a few miner changes. For the sake of brevity, certain basic information contained on the first report has not been repealed, and the reader is urged to consider the two reports as corporation writings.The North Texas area, as encompassed by the two reports, corresponds Railroad Commission of Texas Districts 7P and 9. Oil-development operations in the two districts, since oil was discovered in 1904, have resulted in the recovery of approximately 1,400,000,000 barrels of oil from a proved area that has been estimated to exceed 413,000 acres. During October barrels of oil was produces by primary and secondary-recovery methods from 1,746 flowing wells and 25,211 pumping wells, a daily average 6.6 barrels per well. Of this total volume of oil recovered in October 1947, 47,965 barrels (0.87 percent) was recovered from leases on which water-flooding operations were in progresses."

Feb 1, 1948

By Harold W. Lipper

BUREAU OF MINES helium plants produced a. record-breaking 477 million cubic feet of this essential element in 1959. The supply of helium was less than the demand before operations were resumed at the Navajo plant in July and begun Sit a. new plant at Keyes, Okla., in August. Helium was in abundant supply after August, and the informal allocation system which had been in use intermittently since 1955 was discontinued Delivery of 26 new tank cars in August and September increased the total in the tank-car pool to 163. Defense and space agencies and the Atomic Energy Commission continued to use more helium in their operations and research.

Jan 1, 1960

By Charles B. Carpenter

The New Hope field was selected for study by; Bureau of lanes engineers because many problems met by, the operators during development and operation were unique to petroleum-engineering experience. Solving these problems is believed to have doubled the ultimate recovery of oil from the field. Since the discovery well was 'completed, in April 1943, an oil-productive area of 4,950 acres- has been delineated by the drilling of 64 wells, four of which were dry holes. Four oil-bearing reservoirs - the Bacon oolitic limestone, and the Hill, Pittsburg) and Elledge sandstones, all, in the Trinity group of the Lower Cretaceous series-- have been penetrated at depths ranging from 7,300 to 8,100 feet. Three of these reservoirs were found to be closed-type or solution gas-drive reservoirs, and one - the Hill - was an open-type or water-drive reservoir. During the course of the study, the Tide Water Associated, Oil Co. and -Seaboard al Co. of Delaware made available to the writers all well records, electric logs; and coring, production,, and pressure data. The ,writers performed Certain field and laboratory- tests on cores of ,the reservoir racks and' samples -of the reservoir Oils. Analyses of cores from the four reservoirs showed average .porosities ranging from 10 to 18 percent, average permeabilities of 17 to 297 millidarcys, and -average 'connate water contents ranging from 25.4 to 30.6 percent. Subsurface and recombined samples of reservoir oils indicated that the oils in the Bacon Hill, and Pittsburg reservoirs contained ,206 to 422 cubic feet of gas in solution per barrel initially, and that the, reservoir oils were undersaturated with gas. No samples' of oil from the Elledge reservoir were analyzed, and because of meager data this reservoir was not studied in detail. 4 The presence of free 'gas' or a' gas cap, however, indicated that the oil in the Elledge reservoir was saturated with gas. The rapid decline in pressures in- the' four reservoirs during the 'first year of operation alarmed the operators and provoked them to investigate the reservoir conditions to determine the cause.

Jan 1, 1949

By Mark K. Larson

A constitutive model for rock interfaces based on the principles of static fatigue is proposed. The model is applicable to weak rock or joints with cohesion. Friction and dilation are decreased as plastic work increases. At equilibrium, the creep time increases by one time-step interval, and interface cohesion at each node decreases according to a power function. A constant-load, direct-shear simulation showed that the model is cap- able of mimicking constant-rate and tertiary creep and predicting failure. Tests on core from a coal mine showed constant-rate and, sometimes, tertiary creep, but also weak transitory creep. The cohesion deterioration function may need modification to simulate primary-phase creep. If model parameters are known for a site, the model can predict the onset of tertiary creep and failure. Such predictions can help engineers make better entry design and support decisions, which will reduce the likelihood of roof falls and increase safety for underground miners.

By B. W. Gandrud

[The Bureau of Mines is conducting an extensive investigation of coal preparation in the Alabama coal fields in cooperation with the University of Alabama and coal-mine operators. In this investigation the drainage characteristics of typical coals from the Warrior and Cahaba n fields were studied. Tire main purposes of this study has been to evaluate no nearly as possible relative influences of certain factors on rate of drainage and to determine whether the drainage characteristics of coals from different beds or from different mines on the soma bed differ materially. A further objective was the development of a laboratory drainage test that would predict approximately the rate at which any coal will drain after having been loaded into a railroad car in a saturated condition. The study has been confined to samples of slack coals - that is, coals from which none of the fine sizes have been removed. The samples ranged in upper size limits from 7/16 inch to 3 inches. It did not seem necessary to study nut and egg sizes, that is, sizes from which the fine coal has been removed by screening, as these lose water so rapidly by natural drainage that they present no serious problem in dewatering after treatment in a washer. The significance of drainage characteristics of Alabama coals is apparent in view of the fact that not less than 70 percent of Alabama?s total coal product is subjected to wet washing before being materials.]

Jan 1, 1941

By Henry Kreisinger, WALTER T. RAY

General statement.-The briquetting tests conducted by the technologic branch of the United States Geological Survey had their beginning in the testing of coals and lignites at the Louisiana Purchase Exposition, St. Louis, Mo., in 1904. Briquetting tests were made at the fuel-testing plants at St. Louis, Mo., and at Norfolk, Va. Similar tests to be made at the experiment station of the Bureau of Mines at Pittsburg, Pa., form an essential part of investigations looking to the determination of the fuel value of the coals and lignites belonging to or for the use of the United States. The tests have comprised (1) the manufacture of briquets to determine the adaptability of different coals and lignites to the process and the merits of different binding materials; (2) physical tests to establish the fitness of the briquets to withstand weathering, transportation, and handling; and (3) steaming tests to prove the calorific value of the briquets in boilers of different types used by the Government, and, by comparison with the raw coals, the benefits to be derived from briquetting. Details of the tests have been issued in other publications. list of Government publications on fuel testing and briquetting is given at the close of this volume. Tests at Norfolk.-The fuel tests conducted at Norfolk included a detailed investigation of a number of Virginia and West Virginia coals that are bought by the United States Government for the Navy and for use in constructing the Panama Canal, and are extensively used by the merchant marine, manufacturing plants, and railroads. Through a cooperative arrangement with the Navy Department steaming tests of the coals were undertaken to determine the relative merits of the same coal when burned raw or as briquets in marine boilers. Preliminary arrangements were made between Joseph A. Holmes, then expert in charge of the technologic branch of the United States Geological Survey and now director of the Bureau of Mines, and Rear-Admiral Charles W. Rae, Chief Engineer of the United States Navy. The tests were made on board the U. S. torpedo boat Biddle, designated for the purpose, beginning December 6, 1907, and ending January 27, 1908. The coal used in these tests came from the Sewell and Beckley beds in the New River district of West Virginia. With the particular equipment used in the tests both coal and briquets were far. from smokeless; consequently the data of this bulletin are applicable only by analogy to parallel operation with a coal more nearly smokeless, but nevertheless applicable with much reliability. The possibilities of coals of different composition are indicated by the data to be published in a bulletin of the Bureau of Mines, wherein the present authors describe a number of tests in which only a very slight amount of smoke was emitted while burning raw coal from the Pocahontas No.3 bed, West Virginia, and briquets made therefrom at rates of combustion very much higher than any rates used in the torpedo-boat boiler. At a combustion rate of 120 pounds of the Pocahontas briquets per square foot of grate surface there was scarcely any smoke. It was the original intention to make a set of preliminary steaming tests alongside a dock (which tests furnish material for this bulletin) and to finish with a set of running tests at sea; but the running tests were never made, for lack of time and men.

Jan 1, 1911