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By A. Galaitsis

This report summarizes part of the work performed under the USBM Contract No H0155113, "Noise Abatement of Continuous Mining Machines." It describes the noise source diagnosis of a Jeffrey 120M conveyor and the evaluation of several treatments all conducted in a test facility aboveground. The conveyor noise at the operator's position was gradually reduced from 101.5 to 93 dBA using damping, vibration isolation, sound barriers and smoother discontinuities. The underground performance of the selected treatments will be addressed in Volume II of the report.

Jan 1, 1979

By K. E. Robinson

This study provides an initial indication that mill tailings produced in the Coeur d'Alene Mining District of Idaho can be placed on floodplain areas in a technically acceptable manner without artificial liners and without seriously contaminating the surrounding area. Tests have shown that landfills on these unused areas can result in returning these areas to productive use. The engineering properties of mill tailings permit construction of stable embankments. Designed slope protection inhibits water erosion. Among the environmental considerations in using tailings for landfill construction are the acid and other contamination produced by tailings and wind erosion of exposed tailings surfaces. The initial results indicate that adverse impacts are not as severe as previously thought, and mitigative measures are feasible. Based on the preliminary data, and in accord with existing Federal and State waste management regulations, a conceptual design has been developed for 23 potential landfill sites in the District, which could reclaim 750 acres of floodplain. A cost analysis of landfill construction with mill tailings indicates that the method would be an economically viable means for increasing the valleywide tailings storage capacity, provided construction with slurried tailings is feasible. A Stage H study is proposed to evaluate slurried tailings as a foundation material, as opposed to hauled tailings used in this present study.

Jan 1, 1981

Coal, America's most abundant fossil fuel, is expected to play a key role in our pursuit of energy independence. A substantial increase in coal exploitation will be required if we are to fulfill our future energy needs. It is essential that new developments continue if stable coal prices are to be achieved and maintained. The challenge of the mining industry is to continue these developments in the face of problems related to increasing labor costs, inflation and environmental restoration. With expectations of increased activity in surface coal mining, the U.S. Bureau of Mines has authorized this study to determine the preliminary economic and technologic feasibility of underspoil haulage in area strip coal mines and to identify geologic and geographic areas where such a system could be used. These objectives were met by literature search, data-gathering visits to several active area strip mines and by analyzing various haulage systems that were superimposed on three model mines. Potential advantages of such a system include: 1) improved mine design; 2) lower mine operating costs; 3) improved land reclamation; 4) lower manpower requirements; 5) lower mobile equipment requirements; and 6) smaller, less sophisticated maintenance facilities.

Jan 1, 1975

By J. P. McGee

A 1,000-hour test with a gas turbine at 1,200° F showed a working fluid of 1 gr of ash per 100 scf of power gas (79 percent of the ash 7 to 35 microns in diameter) to be excessive for acceptable blade wear for commercial practicability. Blades in the turbine consisted of about 20 percent each of chromium, cobalt, and nickel; 3 percent molybdenum; 2-1/2 percent tungsten; and smaller amounts of manganese, columbium, and tantalum. Erosion of both the fronts and backs of the turbine nozzles was particularly heavy, the trailing edges being worn to a featheredge. Erosion of the buckets was less marked, although the leading edges were somewhat pitted. A refractory-lined combustor performed efficiently and with little abrasion of the lining by the ash-laden gas.

Jan 1, 1969

By Albert E. Long

During the summer and fall of 1948 the Bureau of Mines, in cooperation with the U. S. Geological Survey, conducted 6xperiments in diamond core drilling in the Phosphoria formation in southeastern Idaho and southwestern Wyoming. Nearly all of the diamond core drilling in the Phosphoria formation has been done by mining companies interested in finding and developing phosphate-bearing beds amenable to stripping. The recovery of sludge; and enough core (usually 30 to 60 percent) to identify certain marker beds produced by current drilling practices meets both the primary requirement of mining companies in determining depth of overburden and their secondary need to determine the phosphate content of relatively thick minable units whose general composition and nature are already fairly well established.

Jan 1, 1949

By Robert Stefanko

The growing demand for energy during the post World War I and World War II periods has prompted underground coal production to increase rapidly. This has been met primarily by mine mechanization, resulting in the development and application of new mining machine types. Correspondingly, the total connected horsepower of each machine as well as the number employed has enlarged rapidly since 1950. (2,3,9,14,16,17) Electrical consumption for each mine has also grown. In the early years of mining electrical applications, only d-c power was utilized underground. Yet, d-c machine limitations were soon realized, and many a-c systems were substituted to permit economic and efficient utilization of a-c distribution and motors. Due to the attractive torque characteristics, ease of distribution and speed control, several traction applications have continued to be powered by d-c motors. The result has been the now prevalent use of mixed a-c/d-c mine power. However, augmented electrical power employment seems to have added to underground coal mining electrical accidents.

Jan 1, 1974

By Robert L. Lagace

The objective of this task was to perform theoretical analyses related to identifying and increasing the understanding of wireless propagation mechanisms in mines, and for predicting the performance ranges and limitations of proposed systems. This was to be achieved by building on and extending previous ADL work* and utilizing experimental data as they became available in the radio frequency bands of interest. B. TASKS Theoretical radio wave propagation investigations undertaken on this task centered on three areas. The first area dealt with extending previous UHF wireless propagation results*: to estimate the losses caused by the presence of haulage vehicles such as trains in coal mine tunnels; to estimate the propagation losses and wireless communication ranges expected along a longwall coal face tunnel; and to assess the applicability of previous analytical approximations to tunnels having reduced crossectional dimensions, such as those found in low coal and in the presence of haulage vehicles. The second area dealt with the development of a suitable propagation model to adequately explain the unexpected, highly favorable LF to MF band wireless radio wave propagation behavior experimentally observed in Consolidation Coal Co.'s Ireland mine. The third area dealt with the formulation of a model for evaluating the overall system transfer function and transmitter requirements for a hoist shaft LF communications system, taking into account the hoist rope/shaft transmission line characteristics, the cage and sheave wheel line terminations, the signal inductive couplers, and hoist shaft signal and noise data.

Jan 1, 1975

By Parviz F. Rad

The Bureau of Mines conducted groove cutting experiments in marble, lime-stone, granite, and quartzite with a 7-inch disk cutter under a normal thrust of 7,000 lb. The values of muck weight per unit length, specific energy, cutting coefficient, and groove depth for each of these rocks were determined for groove spacings ranging from 0.1 to 4 inches, and from these results the values of optimum and critical spacing were computed" The results indicate that compressive strength may be used to predict some of the cutting characteristics of the independent grooves. Considering all the cutting characteristics, particularly those for the interacting grooves, Shore hardness, coefficient of rock strength, and torsional velocity correlate with cutting characteristics better than do other physical properties. Some of the field applications of the principles established in this report are identified.

Jan 1, 1974

By A. B. Hooker

Since man first mined underground, there has been need for adequate illumination; this need has never been fully supplied. At first, suitable lamps were not available. Gradually they have been developed, but along with that development the need for better and better lamps has continued owing to the following conditions and factors: 1. Increasing hazards from gas and dust ignitions. 2. The speeding of operations with mechanized mining, which necessitates greater visibility. 3. A demand that cleaner coal be loaded, which requires higher levels of illumination. 4. The cost of compensation for injuries that has created a demand for better illumination and safer lamps. Use of better lamps has been retarded by: 1. Prejudice and resistance to change on the part of the workers in some districts. 2. The cost and upkeep of the lamps. 3. The present types of lamps, while a great improvement over the old lamps, do not entirely fulfill the requirements for a safe and efficient light for underground workers.

Jan 1, 1938

By B. W. Gandrud, G. D. Coe

"INTRODUCTION The Bureau of Mines, United States Department of the Interior, with the cooperation of the University of Alabama and coal producers of Alabama, is making a series of washability studies to obtain technically and commercially important data from the productive coal beds of the State. Based on the system followed in these studies, this report consists of screen-sizing and sink-and-float data on the America and Pratt beds at Gorgas, Ala.SAMPLING AT THE MINESAlthough operations were discontinued in 1929, the accessible openings of the old Gorgas mines of the Southeastern Fuel Co. made possible the taking of samples from the America bed at three openings and from the Pratt bed at two openings. A sample was taken from the America bed at the Klondyke opening; a second was taken about 1 rile south of the Klondyke at the Musgrove America opening, and a third sample was taken about 1-1/2 miles south of the Musgrove-America at the Cricket Lodge opening. A sample was taken from the Pratt bed at Musgrove-Pratt No. 1, which is about 3/4 mile east of Musgrove-America, and a second sample was taken at Musgrove-Pratt No. 2, which is about 3/4 mile west of Musgrove-America. The samples ranged in weight from 1/2 ton to 1 ton and were equivalent to approximately a 2-ton sample from each bed. Figure 1 shows sections of the beds at the places sampled.In addition to the samples for washability study, a seam sample for analysis was taken at each of the places sampled. So as to give a representative seam sample for each of the two beds, these samples were combined in the laboratory in proportion to the thickness of the bed at the places sampled."

Jul 1, 1939

By Fredrick M. Ryan

Present indications are that in about 2-3 years phosphor tags will be required in commercial explosives. A permissible 254 run ultraviolet lamp assembly has been developed to permit mine inspectors to detect such phosphor tags and therefore to establish if non-permissible explosives were used. This new lamp is powered by a Miner's cap battery without interference with the normal lighting requirements of the cap lamp battery. It is compact, light, and rugged with very high ultraviolet output.

Jan 1, 1977

By Frank T. Greene

An investigation of the quenching behavior of coal dust-air flames was carried out. The literature relevant to coal dust-air flames was reviewed, including information on the agglomeration, sedimentation, and dispersal of dust clouds. The simple equations relating the various concentrations involved in dust flame propagation are given and their implications elaborated. It is shown that the concentration seen by a moving flame in a sedimenting dust cloud can differ significantly from the concentration commonly measured in such experiments. The known dust cloud phenomena which appeared significant in flame propagation studies were experimentally evaluated, and quenching diameters, flame speeds, and lean propagation limits for several tube diameters measured. For Pittsburgh seam coal, the Minimum Quenching Diameter (MQD) for dust between 10 and 20 µm was found to be between 0.7 and 0.8 cm, and the lean propagation for 3.2-cm tubes to be approximately 200 mg/liter. Similar MQD data were also obtained for Pocahontas and Sewell coals, Beulah lignite, and a 50-gal./ton oil shale. The effect of temperature, coal particle size, and propagation tube material were also investigated.

Jan 1, 1981

By F. D. DeVaney

Metallurgists and coal-washing engineers have used heavy liquids for years in studying the characteristics of ores and coal. By such means true separations can be made between the various specific-gravity increments in the materials examined. To use of heavy liquids has permitted determination of the possible grades of tailings and concentrates by specific-gravity methods on any particular size, and therefore the size to which the ore must be crushed to free the valuable material. The simplicity of float-and-sink separation and the high degree of efficiency attained in the laboratory are factors that commend the method for commercial concentrations.

Jan 1, 1940

The objective of this study was two-fold: 1. To perform a world literature search pertinent to the analysis, selection and design of hoisting systems and their components and to codify the search into a literature compendium. The search resulted in a technical data file of over 1500 hard copy items. The compendium index was also suitable for establishing a comprehensive computer-loaded data base on the subject. 2. To develop a comprehensive system of guidelines to cover salient aspects of analysis, selection and design of electrical, mechanical and structural components of a hoisting system with a view to establish parameters for maximum safety and efficiency of operation, installation and revision of the system. 3. Major mechanical components in the hoist and mechanical drive train are considered. Design and specification criteria based on American standards and practices are developed as they apply to typical mine hoist arrangements.

Jan 1, 1988

By Thomas Gales

Longwall mining has a high potential for producing bulk production from a single face. Production is interrupted for a considerable time when it is necessary to move the equipment to a new block of coal. The frequency of such moves can be reduced by increasing the dimension of the block to be moved. Merely doubling the tonnage in a block to be mined may increase production by more than 21,000 tons per year. The time taken to move the equipment can be reduced by careful preplanning, industrial engineering analysis, and specially designed equipment. Reducing its move time from 30 days to five days can increase production by more than 25,000 tons per year. Increasing the panel dimensions and reducing the move time can give an increase in pretax profits of more than $600,000. A comprehensive bibliography is included.

Jan 1, 1977

By F. D. DeVaney

Metallurgists and coal-washing engineers have used heavy liquids for years in studying the characteristics of ores and coal. By such means true separations can be made between the various specific-gravity increments in the materials examined. To use of heavy liquids has permitted determination of the possible grades of tailings and concentrates by specific-gravity methods on any particular size, and therefore the size to which the ore must be crushed to free the valuable material. The simplicity of float-and-sink separation and the high degree of efficiency attained in the laboratory are factors that commend the method for commercial concentrations.

Jan 1, 1940

By Thomas M. Barczak

Wood cribs are used extensively to stabilize openings in underground coal mines. This U.S. Bureau of Mines report describes the results of full-scale testing of several multitimbered wood crib configurations. Multitimbered configurations are wood cribs that are constructed with two or more timbers per layer. Nine different crib configurations were evaluated. Configuration parameters under study included the aspect ratio (height-to-width relationship) and the percentage of solid rr:aterial used in crib construction. Test results and generalized wood crib behavior are discussed and recommendations are made concerning crib constructions to maximize strength and stability. Crib performance is enhanced by reducing buckling effects by decreasing the aspect ratio and geometry considerations that increase the moment of inertia. A cost benefit analysis of multitimbered wood crib configurations is made. Generally, increasing the percentage of solid provides more resistance at less unit construction cost. A comparison of laboratory results and underground observations of several wood pack wall supports suggest in situ load capacity is less than that measured in laboratory testing. Reasons for the apparent decrease of in situ load-bearing capability include load rate effects, stiffness of reaction surfaces, and varying boundary conditions that alter the load transfer mechanics of the crib structure.

Jan 1, 1991

By Edmond Chin

The area encompassed by the political entities included in this study com-prises 11 million square miles or about 15 percent of the total Earth's land area. The bulk of the region is contained on the Asian continental land mass. Australia, the world's largest is-land or the world's smallest continent, alone is almost as large as the continental United States. The islands of New Zealand, New Guinea, Borneo, Sumatra, and Honshu are among the largest in the world. Collectively, they constitute a land area of 1.1 million square miles or an area about one-fourth the size of the United States. The region is noted for its great rivers. The Chang, Huang, Amur, and Mekong are respectively the fifth, sixth, eighth, and eleventh longest rivers in the world. The Ganges-Brahmaputra has created the world's largest delta, which covers 30,000 square miles. Abutting East Asia are the Sea of Japan, Dong Hai, Nan Hai, Bay of Ben-gal, and Arabian Sea. In the Southern Hemisphere, there is the Indian Ocean and the South Pacific Ocean. The Continental Shelf adjacent to the region constitutes a large proportion of the world's readily accessible shelf area. On the other hand, the Philippine and Java trenches and, further out, the Mariana Trench reach to formidable, abyssal depths, downward to 6,000 fathoms. Contrasting to this is Mount Everest, which reaches a lofty height of 29,028 feet. And then there is Xizang, whose high plateaus have been called the roof of the world.

Jan 1, 1992

By H. W. Sheffer

Technical and economic aspects of community refuse disposal systems and their effects on the environment are identified and described. Seven landfills and two incineration systems, located throughout the United States, are reviewed.

Jan 1, 1971

By W. W. Adams

The quantity of explosives sold in the United States in January, 1931, for domestic consumption, amounted to 368,100 kegs (9,202,500 pounds) of black blasting powder, 4,610;000 pounds of permissible explosives, and 16,533,000 pounds of high explosives 'other than permissible. These figures are based on reports received by the United States Bureau of Mines, Department of Commerce, from nearly all manufacturing companies, and include an estimate of sales by several companies that do not furnish monthly reports. Reports actually received from manufacturers showed soles of 365,977 kegs of black blasting powder (consisting of 220,892 kegs of granular powder and 145,085 kegs of pellet powder), 4,687,900 pounds of permissible explosives, and 15,496,152 pounds of high explosives other than permissible. Sales in January, 1931, were smaller than in January, last year, the decreases being 14 per cent for black blasting powder, 19 per cent for permissibles, and 17 percent for high explosives other than permissible. Sales in January 1931 when compared with soles in December 1930, show increases for all three classes of explosives as follows: 2 per cent for black blasting powder, 16 per cent for permissible explosives, and 7 per cent for other high explosives.

Jan 1, 1931