Search Documents

By D. R. Tesarik, M. K. Larson, J. P. Dunford, E. G. Zahl

Western coal mines are operating under increasingly challenging ground conditions. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are cooperating with mines to evaluate how these conditions affect mine opening stability and related miner safety. A system was developed to monitor rock and coal stresses during mining of an entire longwall panel. The system was designed to generate data in near real time to evaluate rock behavior in roof strata and the onset of hazardous conditions as overburden stress was redistributed over working entries during gob formation. Computer simulations and in-mine evaluations were used to optimize instrument placement. A prototype packer assembly was designed and tested for installing sensitive instruments in a mine roof. This paper provides background information on the stress monitoring concept and focuses on the development of instrument placement techniques and the prototype packer assembly.

By H. Billmayer

This report covers the period from June 17, 1974 to February 20, 1975, and describes the work performed in compliance with the requirements of Contract No. H0346102 and Modification No. 1 thereto. The purpose of the contract was to design protective canopies for an Elkhorn Scoop, a Lee Norse Miner, a Wilcox Miner and a Wilcox Bolter; to construct mockups of the canopies; and to obtain machine operator evaluations of the canopy designs by assessing the mockups while installed on their machines in the mines. The overall program objective was to achieve protective canopy designs for the four machines which would be acceptable to the operators.

Jan 1, 1975

By W. L. Dare

This information circular is one of a series, published by the Federal Bureau of Mines, on methods and costs of mining uranium ore on the Colorado Plateau. This report describes the relatively small-scale operations of the Salt Wash miner: The mining method followed, the equipment used, and the production costs. It describes 10 lease-operated mines of Union Carbide: Nuclear Co. that are typical of Salt Wash operations on the plateau. These mines lie within the Uravan mineral belt3/ and arc in the Gateway, Bull Canyon, and Uravan mining districts. (See fig. 1.) Generally the ore bodies occur as irregular, discontinuous layers of ore minerals within sandstone beds in the Salt Wash member of the Jurassic Morrison formation. The ore bodies sometimes occur as rolls, pod associat with carbonaceous trash, or tabular masses. Their size and erratic distribution preclude the use of a prearranged and uniform stoping system. The mining method is simply to follow the ore and leave open scopes behind.

Jan 1, 1959

By Frank E. Federspiel

In 1992, the Bureau of Mines conducted a mineral resource investigation of the 19,200-hectare Garfield Mountain study area in east central Idaho. The area had been proposed for Wilderness. Cretaceous-age quartzite and limestone conglomerates underlie the area's east half; thick travertine beds, as well as limestones, dolomites, sandstones, and volcanic tuffs occupy the west half. All the rocks have been faulted and folded as part of the Western Overthrust Belt. Two, enormous travertine deposits occur in the west end of the study area. The lower deposit, controlled by Faxe Kalk Inc., has at least 200 million m3 (cubic meters) of travertine resources. Most of their deposit is very bright with a high CaC03 content and a low insoluble residual percentage: thus it is suitable for use as a paper and paint filler. The upper deposit, owned by Idaho Travertine Corp., contains 100 million m3 of travertine resources; it is used for facing or dimension stone. Weathered travertine outcrops are buff to tan and locally vuggy. Bureau of Mines samples of' outcrops contained greater than 95% CaC03. Approximately 600 m3 of travertine have been quarried from the two deposits and used for facing stone. Four travertine quarries and two dozer cuts were examined. Faxe Kalk has 103 White Rock placer claims on the lower deposit; approximately one-half of the claims are within the study area. Idaho Travertine has the Limestone 1 and 2 placer claims on the upper deposit. A 4,647-m-deep oil and gas exploratory well was drilled on the east end of the study area without success.

Jan 1, 1993

By C. M. Frost

Crude shale oil produced during in situ retorting by the Bureau of Mines at Rock Springs, Wyo., was refined by three schemes. In the first, the crude oil was fractionated to raw naphtha and 400° F+ residuum. The residuum was hydrogenated over cobalt molybdate catalyst at 815° F and 1,100 psig. The blended raw and 160°-400° F hydrogenated naphthas were hydrodenitrified and then catalytically reformed. The 400° F+ hydrogenated oil was catalytically cracked. In the second scheme, the crude was hydrogenated over nickel-tungsten catalyst at 800° F and 1,500 psig. The hydrogenated fractions were processed by methods used in the first scheme. The third scheme resembled the second but, prior to hydrogenation, the crude was "hydrostabilized" over cobalt molybdate at 500° F and 500 psig. Yields of reformate and cat-cracked gasoline as volume-percents of the crude, and research-method octane numbers (with 3 ml TEL) for the three methods were as follows: First method, 32 pet reformate, 90 octane; 19.5 pct cracked gasoline, 99.2 octane. Second method, 29 pet reformate, 81.1 octane; 21.3 pct cracked gasoline, 99.6 octane. Third method, 28.2 pet reformate, 86 octane; 28.7 pct cracked gasoline, 95.9 octane.

Jan 1, 1974

By William J. Campbell

The Federal Bureau of Mines provided five test materials--amosite, short-and long-fiber chrysotile, crocidolite, and nonfibrous tremolite--to the National Institute of Environmental Health Sciences (NIEHS) for studies on the biological effects of orally ingested asbestos-related materials. An inter-agency agreement between the Bureau and NIEHS made possible this program to characterize these test materials. The Bureau in turn received support through contracts with the Ontario Research Foundation for the milling of amosite and crocidolite, and with the University of Maryland for microscopic measurements. The five test materials, which were supplied in quantities of 960 to 1,200 pounds each, were characterized by chemical-instrumental analysis for elemental composition, surface area, density, X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, mineralogy, and particle size analyses. Particle size distributions were emphasized because of the current theories relating adverse biological effects to length-width characteristics of durable elongated particles.

Jan 1, 1980

By R. W. Stahl, H. E. Sanford, J. B. Benson

"As movement or transportation of coal is second only in importance to actual mining, and as the latter is wholly dependent on the former, the efficiency of the haulage system often determines the efficiency of the entire plant. Safe or accident-free transportation is essential, also, because no attempt is made to divorce safety and efficiency, it being realized that they are inseparable.Most of the Ruhr mines were opened decades ago, and many features that were considered up-to-date then are now obsolete. Progress in developing haulage systems has been slow, chiefly because it would be very costly to change many to accomodate more modern equipment. These systems are being altered or modernized slowly, as capital permits. The only revolutionary changes that have been made in mine haulage are the use of larger locomo¬tives and cars, in the movement of shuttle cars, and in the adoption of skip hoisting. Most Ruhr shafts, however, will not accomodate large cars, the secondary roadways are too narrow for large locomotives, and the coal is too soft to permit skip hoisting because degradation would be too great. Therefore, notable advances have been made only at newer plants, where allowances have been made for modern equipment.The shafts are deep (average 2,300 feet) and of comparatively small diameter. The small bore was designed to reduce costs of sinking and lining. Generally, the shafts are lined throughout with masonry; however, most of the buntons and guides are wooden.The hoisting engines arc installed in masonry structures, and where more than one hoist is used they are placed on opposite sides of the shaft to eliminate as much noise as possible (fig. 1). This arrangement also prevents an engineer from acting on any signals except those transmitted to him. A few hoisting engines are mounted in the headframes (fig. 2). The hoisting engines are equipped with overwind, overspeed, and auxiliary braking devices, which are tested frequently and kept operative at all times. The signal code is displayed in view of the engineer, and a light or dial indicator informs him of the cage's position in the shaft. Many hoists are equipped with re¬cording devices, which show on a continuous chart the speed of hoisting as well as any delays throughout the 24-hour period.A Koepe system of winding is in general use because of the depth of shafts (fig. 3). With this system, a single rope passes over a single-groove, large-diameter sheave attached to the motive power, and the ends of the rope, after passing over the head sheaves, are attached to the cages. A flat tail rope suspended in the shaft and connected to the bottom of the cages serves to balance the system. Both steam and electric engines are used to activate the hoisting system, end the engines are capable of moving at least a 50-percent overload.The ropes are necessarily of large diameter (2-1/2 inches and greater), and flexibility decreases as rope diameter increases. To overcome the unwieldiness .of large-diameter ropes as shafts become deeper, a four-rope system is being tried at one mine (fig.4). In this system the load is equalized between four ropes which permits much smaller ropes to be used. All hoist ropes are inspected daily and discarded after 2 years service unless special permission for longer service is granted by the Mine Inspectorate, and then only after thorough visual and electromagnetic inspection."

Jan 1, 1950

Lignite constitutes approximately 97 percent of the near-surface coal resources in Texas. The most significant bituminous resources are in the north-central and southern parts of the state. Coal reserves in Texas are estimated to be 13.7 billion tons, about three percent of U.S. coal reserves. The average thickness of coal seams mined in Texas is approximately eight feet. Texas gained primacy when its regulatory program was conditionally approved February 16, 1980; the program was fully approved June 18,1980. The state's Abandoned Mine Lands program was approved June 23,1980.

Jan 1, 1992

By Robert L. Mentch

CADMIUM is one of the metals apparently destined to remain relatively scarce. The en tire supply of primary cadmium is recovered as a byproduct, concurrently with the treatment of ores of other metals. Development of the cadmium industry is attributed to metallurgical improvements in the zinc industry; output depends almost wholly upon zinc production. Cadmium is a metal of specialized uses where its superior performance has developed a strong, expanding demand. The supply, however, has been relatively unresponsive to price because of its byproduct nature. Cadmium's outstanding properties would assure it a manyfold greater market if more were available at lower prices.

Jan 1, 1958

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

D. 1 Most Effective Salts A. Ammonium Phosphates Monammomium phosphate and diammonium phosphate (salts of ortho phosphoric acid) are superior to the triammonium salt in fire-resisting properties. Of these two, the monammomium salt is chemically the more stable. It is also held very retentively by a number of woods, thus reducing leaching out of the salt if exposed to water. Saturated aqueous solutions of mon- or di-ammonium phosphates have vapor preservatives corresponding to an atmospheric relative humidity of 9Z to 93 percent, the wood, will, therefore, not attract any moisture at humidities below this figure. Low concentrations (1 lb dry fire-retardant per cubic foot of the dry, treated timber) will stop flame and high concentration (5 lbs. per cubic foot) will prevent smoldering. B. Ammonium Sulphate In low concentrations ammonium sulphate has only a small effect on flame propagation, but its effect is marked when concentrations of the order of 20 percent are employed. It has no appreciable effect on smoldering. It is more corrosive to metals than are the phosphates, but is less corrosive than ammonium chloride or magnesium chloride. It is possible to leach it out of wood by prolonged and continuous action of water The vapor pressure of the saturated solution corresponds to 81 percent atmospheric humidity.

Jan 1, 1976

By James R. Aggson

The theoretical relationships that are used to calculate in situ rock stress magnitudes and directions from borehole deformation data obtained during overcoring are based on the assumption that the rock is a linearly elastic material. Strictly speaking, this assumption is not valid in any rock. Thus, investigators using overcoring techniques must either accept various degrees of nonlinearity and the associated inaccuracies or use core testing techniques that address the problem and compensate for elastic nonlinearity. Previously developed test procedures for stress-relief overcores partially correct for nonlinearity. This Bureau of Mines paper describes a test procedure that completely corrects for elastic nonlinearity in stress-relief overcores.

Jan 1, 1977

By B. E. Davis

The Bureau of Mines conducted tests on samples of two Florida phosphate slimes t6 devise a technique to recover phosphate currently dis-carded because of its fine size. A flotation technique was devised to recover the phosphate contained in two fractions of each slime: the plus 37um fraction and the plus 20-um fraction. The technique involved conditioning the flotation feed with sodium silicate and a fatty acid-fuel oil emulsion, floating a rougher phosphate concentrate, and cleaning the concentrate in two cleaner stages with sodium silicate added to each for gangue depression. Concentrates containing 21.0 to 32.3 pct P20S were produced with recoveries of 68.1 to 84.2 pct of the P20S con-tained in the flotation feed.

Jan 1, 1987

By Robert H. Ridgway

This circular outlines salient facts regarding the manganese-ore industry in the United States and the world. It is founded chiefly upon published information available in the literature of the subject. The Bureau of Mines has in its files additional, more detailed data upon many of the topics presented very briefly here, and will endeavor to assist the mineral industries and public by giving further information in response to individual inquiries. The Bureau will welcome comments, criticisms, and contributions of data that may assist in making later additions of this circular more accurate, or in developing more fully its mineral files pertaining to manganese. In reporting the production of manganese-bearing ores in the United States the following classification has been adopted by the Bureau of Mines: (1) Metallurgical-grade ores, under which have been classified manganese ores containing 35 percent or more of manganese used in the manufacture of iron and steel, ferruginous manganese ore containing 10 to 35 percent of manganese, manganiferous iron ore containing 5 to 10 percent of manganese, and manganiferous zinc residuum; (2) battery ore; (3) fluxing ores, under which are classified ores that may contain a few ounces of silver and are rich enough in manganese to make them valuable chiefly for fluxing purposes in nonferrous smelters; and (4) miscellaneous ores, under which are classified the ores shipped to brick manufacturers, glass makers, and manufacturers of manganese chemicals.

Jan 1, 1933

By R. V. Ramani, R. Bhaskar

One of the primary means of .control of health hazards from respirable contaminants in mine atmospheres is through design and operation of mines to meet mine health and safety regulations and recommended practices. A U.S. National Academy of Sciences study concluded that for significant progress in coal mine dust control, research should be directed more toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust. Theoretical and experimental studies on transport of dust in mine airways, particularly coordinated efforts to validate theory with practice, are scarce. Some empirical models, developed on the basis of experimental data, are available but these models cannot be applied to new .conditions. The purpose of this paper· is to present the results of theoretical and experimental studies on the transport and deposition of dust in mine airways. This study is a part of an on-going research project in the Generic Mineral Technology Center on Respirable Dust. In the paper, the assumptions of the modeling phase of the project and the development of a convection-diffusion equation for dust transport in mine airways will be outlined. The important aspect of the modeling effort.is the capture of the deposition phenomenon. The experiments performed under controlled conditions in a typical mine airway as well as under normal mine operating conditions will be discussed. The comparison of the model predictions ·with experimental results will be made to identify critical areas of agreements and deviations. The implications of the findings and areas for further research and development will be identified.

Jan 1, 1990

By Thomas M. Barczak

The success of longwall mining can largely be traced to the development of powered roof support systems. The most significant improvement in powered support design has been the shield support, which improved kinematic stability and promoted the application of longwall mining in difficult-to- control caving conditions where chock and frame supports were inadequate. The most obvious trend in shield design has been an increase in shield size and capacity. This U.S. Bureau of Mines report examines shield design and operation practices and their consequences for the utilization of high-capacity shield support systems. An optimization goal is to minimize support loading by selecting an active shield setting force that is compatible with strata behavior and shield loading characteristics. Shield stiffness is an important design parameter that is often overlooked. A consequence of increasing shield capacity by incorporating larger diameter leg cylinders is a proportional increase in shield stiffness. Setting forces have also increased in direct proportion to the increase in shield capacity. The increased stiffness and higher setting force cause the available capacity to be consumed more quickly, severely limiting the ability of high-capacity supports to last longer and provide reserve capacity for difficult mining conditions.

Jan 1, 1992

By Lloyd A. Morley

Research performed on computer modeling of mine power systems under USBM Grant G0155003 1S described. The work was performed at the Pennsylvania State University from 5 November 1975 through 4 November 1976. Results presented are interim in nature, and future research is planned to integrate the simulations which have been developed. The thrust of this research has been divided into three main areas. 1. Modification of a previously developed model (Mine Power System Simulation or MPSS) to include interactive operation and the use of default (average) load data. 2. Development of a dynamic simulation of interdependent mine power system induction motors. 3. Development of an approach to modeling of motor shaft loading of induction machines for mining operations. During the course of the current year's research, significant results have been achieved in all areas. Construction of an interactive MPSS model has been completed and checked. This simulation was written in APL code and is fully interactive. In addition, default data representing 158 different pieces of mining equipment has been developed for use with the interactive model. Additional work described includes the construction of a dynamic simulation of interdependent continuous miner induction motors and the development of an approach fo: motor shaft load torque computation from experimental data.

Jan 1, 1976

Assist in controlling or extinguishing fires that occur in abandoned mine lands (AML) by providing a compilation of information on past fire control projects, the estimated extent of the current problem, and factors affecting the occurrence, propagation, and extinguishment of AML tires. Conventional fire control methods and their probable effectiveness are evaluated. Background Fires that occur in abandoned coal mines, waste banks, and coal outcrops constitute a serious health, safety, and environmental hazard from toxic fumes, deterioration of air quality, and subsidence. Although fires on AML occur in every coal-producing State, the severity of the problem varies, with most underground fires occurring in Kentucky, Pennsylvania, and Wyoming. Surface fires are prevalent in Kentucky, Pennsylvania, and West Virginia. Methods to extinguish or control AML fires, including excavation, fire barriers, and scaling, are generally expensive and have a relatively low probability of success (see figures 1 and 2). Bureau of Mines Study The Bureau compiled information from a variety of sources and found that the problem of AML fires is a serious one. Such fires can involve a high degree of hazard and can be difficult and costly to control. AML fires usually involve smoldering combustion in outcrops, waste banks, or abandoned mines. Given the nature of these fires, it is unlikely that the extent of the problem or the cost of solutions will decrease in the near future.

Jan 1, 1992

Improve face ventilation in mines with large cross-sectional entries. Approach Oil shale, salt, and limestone mines typically have large entries. Providing adequate airflow to the working faces of such mines for worker comfort, health, and safety is a substantial ventilation problem. If diesel equipment is used at the face or if a methane hazard exists in the mine, the problem becomes even more complex. To address this problem, a study was conducted under a joint contract between the Oil Shale Committee of the Colorado Mining Association and the Bureau of Mines. The study evaluated two face-ventilation concepts for large-entry mines. Improving Ventilation Two face-ventilation systems were selected for testing of an oil-shale mine, based on results of a cost/benefit analysis. The systems were a free-standing jet fan and a ducted fan operating in the blowing mode. The jet fan was spotted on the intake side in the mouth of the entry being advanced with final positioning, in or out, deter-mined by minimum recirculation. The ducted fan was also positioned in the mouth of the entry being advanced, with its tubing terminating 75 feet from the working face. The mine face entry was a dead heading 55 feet wide, 30 feet high, and 320 feet long. Sulfur hexafluoride (SF.) tracer gas was used to measure the performance of the two systems in diluting mine face pollutants including after-gases from blasting, hot diesel emissions, methane roof layers, and methane emitted from muckpiles.

Jan 1, 1987

The Mine Safety and Health Administration (MSHA) defines an independent contractor as any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine. Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Jan 1, 2008

Enhance hydraulic fragmentation technology by developing alternative grout sealing methods. Traditional grout scaling methods rely on chemical adhesion and require large contact areas to restrict high-pressure fluids. Fluid injection into rock requires economical and effective seals. With economical and effective seals, rock is easily fractured in tension by high-pressure fluid injection (fig. 1). Approach An innovative grouting technique was developed and tested by the Bureau. Slowly hydrating expanding chemicals are placed within a borehole and around a section of high-pressure tubing. Testing was conducted using 9/16-inch-OD smooth-walled injection tubes in 1.5-inch-ID holes. Seal lengths weir less than 10 inches and curing times were less than 24 hours.

Jan 1, 1989