Search Documents

By Manuel Gomez

The purpose of this study was to evaluate the feasibility of using statistical response surface regression analysis to predict the sulfur and ash distributions and the washability characteristics of coal along a seam in advance of mining. Prediction equations were developed with experimental data from channel, bench, and core samples from the Pittsburgh coal seam in Greene County, Pa. It was not possible, with the available experimental data, to construct mathematical models to predict ash and sulfur concentrations between sample points. In the authors' opinion, however, the good agreement between experimentally determined and predicted values at given sample points demonstrates the usefulness of the method. More input data, such as geologic information, seam characteristics (rock-to-coal ratio), petrographic analysis, and chemical data, would perhaps make it possible to predict sulfur and ash concentrations and washability characteristics between sample points.

Jan 1, 1970

By John B. Goodman

This report presents a study of a modification of the precision laboratory carbonization-assay apparatus that renders the unit capable of performance at low-, medium-, and high-temperature assay levels and permits, under controlled conditions, evaluation of the relationship between carbonization temperature and the yield of pyrolysis products. Second, the interest and value derived from the temperature study data directly apply to the particular semiplant carbonization processes and techniques currently being investigated in this laboratory. Data obtained with the assay apparatus enables the fuel technologist to predict the probable yields of carbonization products from pilot-plant operations under various carbonizing conditions. Data obtained with the assay apparatus has been used to predict the product yields of industrial carbonization plants at Kemmerer, Wyo., and Rockdale, Tex. The assay provides a useful tool in detecting, from the carbonized plant product, the degree of effectiveness of pilot-plant operation. Third, the residual volatile matter in some industrial carbons has broad significance. Evaluation of the volatile material remaining with or in the carbon may be assessed through the high-temperature-assay technique. The low-temperature carbonization assay devised by the writers has proved to be a versatile tool in predicting the probable product yields from pilot-scale carbonization processes. The apparatus described in previous publications has been modified to extend the range of testing above 500° C. without impairing the accuracy and reproducibility obtained in the low-temperature range. Results presented here include product yields from a typical Texas lignite and Wyoming subbituminous-B-rank coal over the temperature range 150° to 1,000° C.

Jan 1, 1958

By A. J. Barry

A method was developed for testing the anchorages obtained with 3/4-inch, expansion-type, headed bolt and shell assemblies. The apparatus is a modification of that used in testing -inch-diameter, slotted-type bolts. Four makes of expansion-type shells were used in 64 tests made in sandstone and shale roof. The results show that for 3 makes of shells the anchorage effectiveness is independent of the installed land, and for the fourth make of shell a better anchorage is obtained when instilled at a load of 8,000 pounds. The results also show that deformation of the expansion plug influences the majority of the anchorages obtained with two makes of shells. This deformation causes a larger increase in displacement for a given added increment of load. The data from 48 of the 64 tests were combined to establish a relationship between average displacement and increase in bolt load (above the installed load). This relationship can be used to evaluate the anchorage effectiveness of any 3/4-inch-diameter, expansion-type, headed bolt and shell assembly tested in the field.

Jan 1, 1956

By Thaddeus B. Evans

This information circular is one of a series describing mining methods and costs, being published by the Bureau of Mines. The Sunbright mine of the Foote Mineral Co. at Sunbright, Va., is the southernmost underground limestone mine in the State. It is a comparatively recent operation, and a description of its rapid development to production stage may have particular interest for the limestone-mining industry. ACKNOWLEDGMENTS Acknowledgment is made to the executives of the Foote Mineral Company including F. B. Shay, vice president in charge of production, W. B. Towner, general production manager; and to the members of the company staff at Sunbright for their assistance in preparing this paper.

Jan 1, 1957

By R. F. Tenney

No detailed information has been published heretofore on the performance of small industrial-type anthracite stokers in building-heating service, apparently because of the difficulty of comparing the performance of one unit with that of another over an entire season's operation. Studies of competitive heating fuels have been similarly handicapped, and attempts to compare fuels are seldom technically sound in this investigation, the performance of a 60-in. Losch4 stoker burning rice-size anthracite in a standard commercial boiler was observed during a 4-month winter-spring season. It was used to heat two buildings at the Bureau of Mines' Anthracite Research Center at Schuylkill Haven, Pa., with the customary type of automatic pressure-range control. Attendance was limited to inspecting, fuel weighing, data recording, and ash removal. Results were computed daily and grouped by weekly periods to minimize daily irregularities. The same stoker-boiler unit had already been tested in a series of American Society of Mechanical Engineers (ASME) test code runs, with the stoker running continuously and with other conditions well stabilized A comparison of results from the code test and the building-heating tests provided information not available in the past for a single stoker unit, assisted in analyzing heat losses not computable in a cyclic operation, and established a basis for evaluating stoker performance in heating service.

Jan 1, 1963

By Edward F. Divers

This Bureau of Mines report describes the results of a program to develop small, rugged scrubbers with high dust collection efficiency for use in under-ground coal mines. The Bureau's Pittsburgh (Pa.) Research Center has developed and assisted in the development of several types of improved scrubbers that are especially suitable for various underground mining applications. Research efforts concentrated on reducing the size, power, and water consumption of these scrubbers, while optimizing their dust collection efficiency. Fractional dust collection efficiency, air volumetric range, size, power, water consumption, and application guidelines for each type are described. Air pressure differentials ranged between 2-and 3D-inches water column (wc). The dust collection efficiency of six scrubbers--a venturi, two flooded-fibrous-bed, a venturi-impaction plate, a wetted-fan, and a rotating flooded-bed--were compared. The rotating flooded-fibrous-bed and the stationary flooded-fibrous-bed scrubbers showed the highest coal dust collection efficiency. Test results show that these scrubbers can generally achieve respirable size coal dust collection efficiencies in the high 90-pct range required to reduce both long-(8-hour) and short-term coal mine dust concentrations below Federal requirements.

Jan 1, 1979

By John C. Ferm

This report contains a summary of Phase I and complete results of Phase II portions of a study of geologic factors associated with roof falls in mines on the Pocahontas #3 coal seam in southern West Virginia and southwestern Virginia. Principal objectives of Phase I was the selection of five mines that best portrayed the spectrum of roof and mining conditions and Phase II consisted of a measurement and documentation program for each of the five mines. The documentation measurement program included reconnaissance mapping, detailed mapping, joint measurements and coring roof rock. 1.2 PHASE I RESULTS The results of Phase I consisted of the selection of the following five mines for detailed study: Virginia Pocahontas #3 (Island Creek Coal Company), Bishop (Consolidation Coal Company), Shannon Branch (Allied Chemical Company), Keystone II (Eastern Associated Coal Company) and Macalpine-East Gulf (Westmorelenad Coal Company). In addition, Phase I results, which were based on questionnaire data, indicated that the kind of rock in the roof --gray sandstone, crystallized sandstone, laminated sandstone and shale, grey shale, slickensided shale, and rider seams could be associated with good and bad top areas. Also presence of vertical separations, bolt length, entry and cross-cut width, length and torque on bolts and depth of overburden seemed to be related factors. These data provided a focus for the Phase II measurement program.

Jan 1, 1975

By J. B. Janus

This report, the 25th in a series, lists analytical data of coal samples collected by the Bureau of Mines in connection with the purchase of several million tons of coal for various Government agencies during fiscal year 1975. Tipple samples were collected by Bureau of Mines engineers at tipples as coal was being loaded into railroad cars or trucks. Ultimate analyses are given for these coalbeds only. The delivered coal was sampled at destination in accordance with instructions furnished by the Bureau of Mines, and all samples were analyzed in the Bureau laboratory at Pittsburgh.

Jan 1, 1976

By R. H. Sprute

The Federal Bureau of Mines performed laboratory tests using direct current to dewater and densify fine-grained coal sludge in order to alleviate disposal problems and lead to recovery of high energy value often present in this waste. The laboratory tests described in the main body of the report were performed on thickened underflow (no flucculant added) from a northern Appalachian coal preparation plant. Solids in this slurry was very fine with 65 percent of the particles less than 0.1 mm in diameter. A variety of application procedures tested is exemplified by a test in which a soupy slurry (55 percent dry-weight moisture content) was converted into a firm dense material with a 20-percent dry-weight moisture content. These results were achieved in 3 hours with current density of 3.7 amp/ft2 and a power expenditure of 35 kwhr/yd3. The treated material has an average heating value of 10,400 Btu/lb. Varying current density, electrode configuration, and placement depth makes application of the treatment flexible. Two other types of sludge were tested briefly--thickener underflow from a southern Appalachian coal preparation plant with flocculant added, and sludge from an acid mine drainage treatment plant. The underflow responded well to the treatment, but response of the sludge from the acid mine drainage treatment plant was poor.

Jan 1, 1976

By A. Z. Dimitroff

An improvised rock- dust disseminator, consisting of a 10-gallon galvanized metal milk can that dispenses rock dust in return air currents by the injection of compressed air has reduced the float dust explosion hazards at the Koehler coal mine, Koehler, N. Mex.

Jan 1, 1965

By A. B. Hooker, E. J. Coggeshall

"INTRODUCTION Ignitions of gas at the coal face when a blast is fired electrically are often a tributed to the explosive; but sometimes the ignition cannot be explained satisfactorily in this way-in fact, ignitions have occurred when the detonator has failed explode.The possibility of such electrically by sparks from the blast between poorly insulated leading wires and detonator leg have been recognized. Several countries have provided safe types of single-shot blasting units; some have permitted the use of larger multiple-shot blasting units provided each unit is equipped with a time-limiting switch that prevents unnecessarily long application of voltage on the leading wires after the shot has occurred, the assumption being that the firing line will this be dead before damage to the wires and subsequent sparking can take place. An extensive research was made by a French commission relative to the characteristics of electric detonators and methods of firing. Along other tailings they investigated the probability of ignitions by sparks across the leading wired at the face, also the time and duration of the various events in blasting, such as ignition of the detonators, movement of the coal face, and application of firing current. They suggested, as a means of eliminating or reducing tilt possibility of gas ignitions from the blasting unit, that the timing switch of the blasting unit be designed to disconnect the blasting"

Oct 1, 1934

By J. B. Zadra, S. M. Shelton, M. M. Fine

"Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced; although it is well known that there are large deposits of low-grade ore in the United States, the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to procure adequate supplies from foreign sources. Consequently, a program of laboratory and pilot-plant investigation designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines.This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program. The scope of the program and the organization that woo set up to direct and supervise the work were discussed in the foreword of the first paper of this series, Report of Investigations 3606, Manganese Investigations. 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent, and C. R. Schack. Other reports will be published as the work progresses."

Mar 1, 1942

By Ernest L. Corp

The natural marine environment can be divided into four basic categories: the air-sea interface, the water zone, the seafloor, and the subbottom. Efforts are being made to accumulate data to delineate the conditions in each of these areas and to conduct engineering studies which will determine how these environmental parameters affect the mining process. Laboratory facilities have been constructed and equipment and techniques for scientific data collection and laboratory research have been developed. Major emphasis is being placed on studying the subbottom material. The objective of this emphasis is to study the engineering properties of marine placer deposits in order to assess their influence on the design and performance of the various mining subsystems involving penetration, excavation, transportation, and disposal. Presented are the results of engineering properties tests on a placer simulant which is currently being used for model and prototype testing of coring tools. The effect of these engineering properties on penetrability, core recovery, and sample recovery is discussed.

Jan 1, 1970

By P. G. Clites

This study was conducted to determine the patterns of heat transfer to water-cooled copper crucibles during vacuum arc melting. Values of heat flux from the ingot to the crucible were determined during nonconsumable electrode vacuum arc melting of zirconium and during consumable electrode vacuum arc melting of titanium) zirconium) and steel. The results of these studies con-firm the existence of a high thermal resistance between the ingot and the crucible wall which results from the shrinkage of the ingot as the metal solidifies. Maximum heat flux occurs near the top of the ingot where maximum values of heat flux of 1.4 X 106 Btu/ft2 hr were observed during small-scale consumable electrode arc melting of zirconium and titanium. The maximum heat flux for consumable electrode arc melting of 8-inch-diameter ingots was 0.5 X 106 Btu/ft2 hr. The effects of electrode material) electrode diameter) arc current) and arc potential on heat flux from the ingot to the crucible were studied. Data were also obtained on crucible wall temperatures and on the effect of very narrow annular water jackets.

Jan 1, 1967

Water pollution has been an integral part of most mining operations in the past. Most mine planners had designed their mining operations with little or no regard for prevention of water pollution. The main planning element was always the economics of mineral recovery. Quite often the cheapest means of mineral recovery resulted in the largest water pollution problems. Recent water pollution laws have introduced a new economic element - water pollution control costs - to be considered in mine planning. Water pollution control costs can be extremely high. Foresighted planning can minimize these costs and provide better water pollution control. Effective pollution control preplanning can eliminate pollution from active mines and minimize pollution that may occur after completion of mining. Presently available technology can practically eliminate water pollution by treatment of the mine water. Use of water treatment during mining has no effect on the levels of water pollution after treatment ceases and the mine is abandoned. Therefore, this section of the report deals with preplanning to reduce water pollution, both present and future, by using at-source control techniques. Proper planning of mining and pollution control techniques should follow the concept of a complete, comprehensive reclamation plan. This plan should have control measures designed for all phases of mining from initiation through completion. Preplanning involves acquiring complete information concerning the future mine site, defining the reasons why mining could cause pollution from the site, and determination of available techniques to prevent or minimize formation or transportation of pollutants. Location of haulage and access roads and other mine related facilities should be included in preplanning for water pollution control. Mine site planning is the primary step in establishing any new mining area and is the key to a successful, non-polluting and economical

Jan 1, 1973

Great strides have been made in recent years to reduce the disaster potential of underground mine fires. However, mines can still be caught unprepared for a fire emergency. Fires can grow too large before they are detected, warning systems can be too slow and uncertain to reliably signal the danger, and suppression systems can be inadequate to extinguish the flames. New mining systems and equipment may create unanticipated fire hazards, and new materials may generate highly toxic combustion products. This report contains papers that summarize recent significant developments from the Bureau of Mines mine fire protection research program relating to these problems. Certain of these findings are also applicable to surface mining operations. The papers fall into the general categories of fire detection and instrumentation, fire warning, fire suppression, diesel equipment, spontaneous combustion, and toxicity analysis of combustion products.

Jan 1, 1988

By J. B. Gayle

Because economic and geographic factors have focused particular attention on the use of anthrafines in blends containing Lower Kittanning coal as the low-volatile component, samples from this particular bed were selected for experimentation whenever practical. Carbonizing tests were carried out in accordance with standard procedures, using the Tuscaloosa and sole-heated ovens. Most of the results are in general agreement with those reported by previous investigators. Specific findings are as follows: (1) The effectiveness of anthrafines in reducing coal expansion is such that even highly expanding, low-volatile coals can be carbonized safely with suitable additions of anthrafines and careful control of charge density. (2) Increases in coke size, resistance to shatter, and apparent specific gravity appear to be characteristic for additions up to approximately 15 percent to a fixed base blend. When anthracite of minus-48-mesh size was used and the proportion of low-volatile coal simultaneously increased, these indexes increased only slightly or remained substantially constant. (3) No increase in breeze formation was noted for additions in amounts up to 15 percent. (4) Abradability of coke was increased by additions of anthracite of No. 5 Buckwheat size, but it either decreased or remained sub¬stantially constant when the inert was ground to pass a 48-mesh screen.

Jan 1, 1956

By C. E. Augustine, P. Nicholls

"INTRODUCTION A layer of soot on the heating surface of a boiler decreases efficiency because it increases resistance to the flow of heat, with the result that the heat transfer to the water is lower and the temperature of the flue higher than they would be if the surface remained clean. The percentage of reduction in heat transfer depends on the position and area of the sooted. The percentage of reduction in heat transfer depends on the position and area of the sooted surfaces, the thickness of the most, until the percentage of the total heat absorbed by those surfaces when clean; thus it will vary with the type of boiler and in particular with the ratio of the area of the convection heating surface to the total area. Medium-size and large boilers usually are equipped with soot blowers, and tests have been published giving the increase in efficiency resulting from removal of the soot. Fuel savings up to,8 percent have been reported, but 4 to 5 percent is probably more conservatives. However, these savings may not be due wholly to a reduction the thermal resistance of the surfaces but may be due partly to improvement in the combustion because of better draft or more uniform flow of the gases. In addition, the deposits on the surface of boilers include as a clinker, and as the size of the boiler and the rate of burning increase very little or none will be soot.There are no corresponding test data on small boilers operated at low rates of burning. In stall boilers, deposits are much thicker, and it might be expected that the reduction in efficiency would be greater; in fact, statements have appeared suggesting that the decrease may be as high as 50 percent. This investigation was undertaken because the Bureau frequently receives requests for authoritative information on the effect of soot in small and other heating boilers."

Feb 1, 1935

By Jerry W. Stengel

The Bureau of Mines subjected two manufacturers' chemical oxygen (K02) self-rescue breathing apparatus to a series of laboratory environmental treatments designed to simulate various conditions in underground coal mines. The environmental treatments consisted of extremes of temperature, shock, and vibration. The tests were designed to be used as predictors of the ability of the self-rescuers to survive those environmental insults with no degradation in their protection to the wearer. Based on the severity of the treatments, simulating conditions more severe than offered by the mining environment, the two apparatus tested should be able to withstand the abuse offered by the mining environment and still function as intended in an emergency. Correlation of these tests with results of long-term field evaluations is needed to provide confidence in the laboratory tests as predictors.

Jan 1, 1982

By J. Bender

The objective of this research was to (1) Further develop cyanobacteria mats' for metal-tolerance and cold-tolerance, (2) test them for durability in the field environment and (3) assess them for metal sequestering potential with actual and simulated field samples. Results show that mats performed well In the field and effectively sequestered metals from actual and simulated field samples. Metal uptake from Iron Mountain Hine samples was for Ins 87%, Cu and Cd 99%, Initial concentrations (mg/L) were Zn = 3,250, Cu , 279, Cd = 28. In solutions simulating the Gulf Tunnel drainage, Zn and Mn were effectively removed by mats immobilized on glass wool. Effluent water, after treatment, generally had a Ph of 7 .5-8.5. Al though the final metal concentrations in the mats 'harvested from the decontaminated water were only 1% or less, the actual mechanism of metal deposit was probably a mat-mediated alteration of the environmental conditions causing the metals to deposit outside the mat as oxides or carbonates. Bioflocculents, released by the mats, were likely involved in the metal-removal process.

Jan 1, 1996