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The Bahamas Oil Refining Co. (BORCO) refinery in Freeport continued to operate at less than half its full 500,000-barrel-per-day capacity. Although owned through subsidiaries by the Carey Energy Corp (65%) and Standard Oil Co. of California (35%), BORCO is ineligible for participation in the Crude Oil Entitlements Program granted to companies operating within the United States proper or its territories. Like some other Caribbean refineries, BORCO has suffered a loss of normal market outlet due to the wt advantage afforded U.S. refineries by the Entitlements Program. Saudi Arabia, Nigeria, and Libya are the major suppliers of crude for the refinery. Its principal products, motor spirits, aviation fuel, distillate fuels, and residual fuel oils, were marketed in the United States and Puerto Rim. The Government-owned Bahamas Development Corp. and Burmah Oil Co. Ltd., held discussions pertaining to a renegotiation of Burmah Oil's management contract for the Grand Bahama Oil Transshipment terminal. The desired contract modifications were not made public but financial problems have plagued the terminal and its operation since construction started in 1972.

Jan 1, 1981

By Michael A. Evanto, George J. Karabin

The Mine Safety and Health Administration, Pittsburgh Safety and Health Technology Center, Roof Control Division, is routinely involved in the evaluation of ground conditions in underground coal mines. Assessing the stability of mined areas and the compatibility of mining plans with existing conditions is essential to ensuring a safe working environment for mine workers at a given site. Since 1985, the Roof Control Division has successfully used the boundary-element method of numerical modeling to aid in the resolution of complex ground control problems. This paper presents an overview of the modeling methodology and details of techniques currently used to generate coal seam, rock mass, and gob backfill input data. A summary of coal and rock properties used in numerous successful evaluations throughout the United States is included, and a set of deterioration indices that can aid in the quantification of in-mine ground conditions and verification of model accuracy is introduced. Finally, a case study is detailed that typifies the complexity of mining situations analyzed and illustrates various techniques that can be used to evaluate prospective design alternatives.

Jan 5, 1999

By Joanne L. Johnston

Researchers at the U.S. Bureau of Mines have developed a new technique for bonding strain gauges to rock bolts. These instrumented bolts are used to determine load at intervals along the length of the bolt so that reliable, consistent measurements for the design of support systems can be obtained. In this Information Circular, this technique is described in detail and should result in improved miner safety in underground mines.

Jan 1, 1993

By Raymond W. Hiteshue, Henry H. Ginsberg, Paul S. Lewis

Coal was gasified in the presence of up to 3.57 million roentgens of gamma rays by the Bureau of Mines to determine whether the irradiation increased the gasification rate or yields of methane and hydrogen . High volatile A bituminous coal was gasified with steam at 500 and 1,500 psig and temperatures of 1,400 ° and 1,800 ° F ; five other coals ranging in rank from lignite to anthracite were gasified at 500 psig and 1,800 ° F. The average results of replicate experiments with and without radiation were compared for possible effects of radiation from 40,000 curies of radioactive cobalt . The irradiation had no gross effect on the gasification rate or on the yield and distribution of methane and hydrogen . It was concluded that gammaray irradiation produced no improvement in the technology or economics of coal gasification .

Jan 1, 1964

Apply state-of-the-art monitoring and computer systems technology to remotely monitor geostructural data and evaluate ground conditions in near real-time. Background Recently, the coal mining industry has progressed dramatically from a labor-intensive industry to highly mechanized and automated systems achieving significantly higher production rates. In underground longwall coal mines, production and face advance rates have increased by almost tenfold in the last 15 to 20 years. With increasingly high advance rates, geologic anomalies which affect rock mass quality are encountered more frequently, far exceeding the current rate at which ground control information can be processed and analyzed. As a result, mine operators find themselves with insufficient time or resources to cope with the rapidly changing ground conditions. To keep up with the technological advancement in mining and the associated ground control problems, the Bureau of Mines is conducting a multi-phase research pro¬gram to implement a computer-assisted Ground Control Management System (GCMS). Research is ongoing at present, but when completed the system will be designed to 1) monitor and evaluate data on rock properties, geologic conditions, and rock mechanics data from underground sensors in near real-time; 2) interpret the analyses to evaluate the interaction between various critical ground control parameters; 3) assess the structural integrity of the mine; and 4) determine failure modes and provide recommendations for control measures, design modifica¬tions, and alternative support procedures. The system will be expanded into its full capability during various phases of this research program.

Jan 1, 1991

By H. B. Brunot, L. C. IlsLey

The chief object of the Electrical Section of the United States Bureau of Mines is the study of causes and means of preventing accidents resulting from the use of electricity in mines . A large part of this work for the last 20 years has been the inspection and testing of mining equipment under the provisions of schedules which give the minimum requirements considered essential for the safety of equipment intended for use at or near the working faces of dusty or gassy mines . During the first few years of this work , particular attention was paid to the explosionproof features of the various accessories such as motors , controllers , and other parts . The knowledge of the essentials necessary for safe designs of enclosures has since been augmented by field experience and by data obtained in testing a large number and variety of designs . With our present knowledge it would seem that a disproportionate stress was placed on making the various enclosures explosionproof , but not enough thought was given to the danger from wiring and connections outside of explosionproof enclosures . The list of equipment that has met minimum requirements for safety and has been approved as permissible by the Bureau of Mines includes storage - battery locomotives , power trucks , drills , loading machines , conveyors , cutting machines , room hoists , pumps , concrete mixers , and rock-dusting machines . The wiring on some of the machines is comparatively simple and sometimes , except for the trailing cable , may be entirely within the explosionproof enclosures . In general , there is outside wiring between enclosures , and on the larger machines the wiring may be extensive and complicated . In considering the safety of wiring for mining machinery , attention must be given the severe service and unfavorable surroundings imposed by mining conditions . Some of the matters that require consideration are : ground . The lack of care of the exterior wiring to be expected in the average mine . The lack of adequate periodic inspection of the wiring . The absence of adequate facilities for satisfactory inspection and repairs under- The severe conditions of moisture , dirt , mechanical injury , and low voltage encountered in mining service .

Apr 1, 1931

By Edward L. Burwell

The Bureau of Mines investigated the use of dilute polymer in brine solutions to increase the efficiency of air in gas flooding model oil reservoirs. Slugs (0.23 pore volume) of 500 ppm polyacrylamide were injected into a model, consisting of a high- and a low-permeability core, that had been previously gas flooded to residual oil. Gas flooding was then resumed. Of the total gas volume injected, the percentage entering the high-permeability zone was greatly reduced after polymer injection but remained unchanged when slugs of water without polymer were used.

Jan 1, 1970

By D. S. Harper, C. O. Carman

A German coal planer was put in operation in the Keystone mine of the Eastern Associated Coal Corp. , Keystone , W. Va . , in August 1960 . At present , the planer is mining in the fourth panel . The blocks of coal mined were 340 by 1,900 feet in panel 1 , 340 by 1,660 feet in panel 2 , 590 by 1,900 feet in panel 3 , and panel 4 , currently being mined , is 590 by 1,900 feet . Almost one- half million tons of coal have been mined from these four panels . An 11 - man crew handles the complete planer operation and produces an average of 500 tons of clean coal per shift . Self - advancing hydraulic props are used to support the roof over the entire face . Roof control and action on all of the panels has been highly satisfactory . During periods of extreme pressure , some additional support is required in the tail entry where evidence of weight from the retreating longwall extends about 200 feet outby the face . The time lost from production by moving equipment between panels has been reduced steadily . The move from panel 3 to panel 4 required 5 days , but it is believed that even that time could be reduced .

Jan 1, 1963

By ROBERT R. ROUGH, FRANK L. BACON, John Dasher

(being shipped as bailast in ocean freighters). Within the last 10 years it has become more economical to use local sands, and there has been a general shift from the Belgian sand. Deposits of purer sand were treated and used for 'some time: but the suprly became limited, and means were sought to beneficiate the more bountiful subpay-f impure beach sands. These sands are composed of, 50 percent feldspar and 50 percent quartz, with small amounts of iron- bearing minerals, The most objectionable impurities in these West coast sands are the oxides of iron and aluminum. The Del Monte (Calif.) beach sand contains about 0.13 percent FeqQg and about 11.0 percent Aig03 (the latter being furnished by the large amount of feldspar present.) For the manufacture of feldspar present.) For the manufacture of flint-glass containers the maximuni quantities of these two impurities permitted in the sand are 0.05 percent F20 and 6 to 8 percent A1203.. The Fe0g occurs in the sand as follows: Traces of iron-bearing minerais resistant to weathering, ferruginous clay stains on the sand grains, and iron minerais not visible and possibly in solid solution or as colloidal incisions in the grains of feidspar or quartz. A good part of the iron in the sand is present in the traces of iron-bearing minerals, biotite, ilmenite, garnet, monazite; and hornblende. Biotite is present in larger quantities than the others. Samples of quartz, were freed of iron-bearing minerais by the use of heavy liquid (sp.gr. 2.70), leached with boiling HCI and SnCl2. Under a microscope a few apparently clean quartz grains were selected, and Fe203 was determined spectrographically to be 0.03 percent. The technique is similar to that described by Gabriel and Slavin. 4/

Dec 1, 1943

By Donald N. H. Chi

This Bureau of Mines report is concerned with a theoretical study of the aerodynamic response of a single mine entry to flame-induced disturbance. The unsteady, one/dimensional, compressible flow equations were solved using the method of characteristics. This study was primarily undertaken to determine the feasibility of extending the method of characteristics to study the aero-dynamic response of complex mine networks. It was demonstrated that although the technique has merit in studying the complex wave interaction in single entries, it appears to be too unwieldly and too expensive for network analysis. Effort was also directed at a further study of the dispersion and filtering characteristic of aerodynamic disturbances in mine passageways.

Jan 1, 1975

By Roy C. Bartholomae

An accurate characterization of the vibration environment and a vibration qualification test derived from it will be a very useful tool for manufacturers of instrumentation for use on underground coal mining equipment. Recognizing this, the Bureau of Mines sponsored a study wherein vibration levels were measured on mining equipment to form a basis for developing the required vibration test. The data base was composed of 160 samples taken at different positions on a variety of underground machinery. The data were analyzed and presented in a format typical of military vibration qualification tests. The form was shown to be virtually identical to the swept sine test envelope specified in MIL-STD-810B for tracked vehicles.

Jan 1, 1982

By J. L. Ellenberger

The National Institute for Occupational Safety and Health (NIOSH) has continued the research role of the former US Bureau of Mines (USBM) to engineer techniques that will reduce the hazards in the mining workplace associated with coal bumps. Recent research focused on a longwall coal mine in Utah with overburden greater than 750 m (2,500 ft) containing several massive sandstone units. The primary field instrumentation at the site was three-dimensional, full waveform, autonomous microseismic arrays placed underground and on the surface in order to surround the active multi-panel longwall district. The purpose of these arrays was to help investigate the strata mechanics associated with the redistribution of stress and the associated gob formation of the longwall. Specifically, the seismic arrays were used to determine the timing and location of the failure in the strata surrounding the active mining. Overall 13,000 seismic events were detected and located with on-site processing during the five months the panel was being mined, including a magnitude (ML) 4.2 event. Of these, a smaller subset of 5,000 well-located events was selected during post-processing to form a consistent data set for analysis in this paper. From this data set, it was observed that the seismic events generally occurred in advance of the longwall face, both above and below the panel, consistent with failure of the strata in the forward stress abutment zone. Also, the occurrence of the ML 4.2 seismic event within 150-180 m (500-600 ft) of a deep cover longwall face with no associated bump caused a re-evaluation of the nature of the connection between seismic activity and coal bumps.

Jan 1, 2002

By R. V. Ramani, C. B. Manula, A. Owili-Eger

All the input data required to operate the ventilation simulator except the title, are entered with I10 or F1O.O formats. The title is entered with (18A4) format. The floating points are designated by (FP) and the integers by (INT)

Jan 1, 1975

Lower the respirable dust expo-sure of longwall mine workers by reducing the amount of air-borne respirable dust generated during coal extraction. Approach Increase the moisture content of the coal seam through water infusion before the coal is mined. How Water Infusion Works Increasing the moisture content in coal tends to prevent respirable dust from becoming air-borne during mining and transport. The moisture content of the coal seam can be increased by infusing water into the seam. Water under pressure is forced into the cracks (cleats) of the coal seam through sealed bore-holes. The effectiveness of water infusion is a function of the amount of water the coal seam accepts (its infusibility), which depends on the cleat density (cleat spacing) and cleat size (crack diameter). Thus the effect of water infusion on dust control depends mainly on coal seam characteristics. Water infusion techniques are generally used to restrict the flow of methane gas to the working face; however, the technique provides an alternative dust control method in mines with severe dust problems which limit production.

Jan 1, 1987

Measure dangerously high concentrations (20 to 500 g/m3) of flammable, airborne dust. Approach Development of high concentration dust monitor (HCDM) which will measure mass concentrations of air borne dust by the principle of beta-ray attenuation. How It Works The HCDM is a battery powered, portable instrument that weighs 10.5 kg. It is capable of making continual (10 sec. time resolution) measurements of high concentrations of airborne dust and can record up to 8 hours of data in an internal memory. The data can be read out later on an analog or digital recorder. An internal pump pulls airborne dust into the sampling section, which contains a low-energy beta-ray source and a Geiger counter detector. No beta radiation escapes from the instrument, and no license is required for the operator. The mass concentration measurement is made while the dust is still airborne. Beta-ray attentuation is independent of particle size and composition of the dust, so the HCDM can he used with many types of dusts which may be airborne in flammable concentrations. A knowledge of the composition and minimum explosive concentration of the dust is necessary to understand the significance of the data from the HCDM. The HCDM was designed to measure air-

Jan 1, 1982

By S. B. Robertson, D. R. Dolinar, G. E. Hinshaw, G. M. Molinda, D. M. Pappas

Rock falls in coal mines cause many injuries each year. Most of these injuries are not caused by major roof collapses, but from falls of smaller rocks from the immediate top or roof skin. Even though safety professionals and mine operators strive to reduce these types of injuries, there has not been a substantial decrease in the rock fall injury rate over the past decade. Various surface controls are used in mines to control the roof skin. One control that has proven to be very effective is roof screening. Roof screen effectively controls roof skin and provides a high roof surface coverage. Although many mines are reluctant to use screen for primary skin control because of the additional costs of time and materials, others are having great success at controlling both the costs and surface rock. In this study, injury data are presented that show a dramatic reduction in roof skin injuries when screening is used. Much of this success is due to the protection from falling rock that the operators receive from roof screen. Five case studies in which roof screen was used are presented along with the associated costs of materials, impact on bolting advance rates, and potential ergonomic risks. The effects of roof screening on skin control and safety are also included. Finally, this paper provides information about best practices and features of roof bolting machines that affect production and safety.

By P. W. Jeran, M. C. Irani, D. H. Lawhead

The Beckley mine is one of five new mines in a heretofore unmined portion of the Beckley coalbed. The remoteness of these new mines from prior mining and their greater overburden preclude applying methane emission experience obtained in the old mines. Four sections of the Beckley mine were monitored. The data gathered show that variations in methane emission cannot be explained by variations in coal production. Although overburdens varied by as much as 30 pct, no correlation with methane emissions could be determined. The rib emissions increase with increased length of rib from a section advancing into virgin coal and do not decline over a prolonged idle period (32 days) whereas some decline has been measured for a section not mining into virgin coal. The indication is that degasification prior to mining will reduce the hazard of methane emissions in this area of the Beckley coalbed.

Jan 1, 1977

By Richard A. Winters

In 1987, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 334-acre Mountain Lakes Wilderness Study Area (OR-011-001) in order to evaluate its identified mineral resources. The study area is located in Klamath County about 15 miles northwest of Klamath Falls, Oregon, and is adjacent to the Mountain Lakes Wilderness. The area is underlain by Pliocene-age basaltic andesite. No mining districts are in the study area nor were any claims recorded or found. There are no oil and gas lease applications. There are no identified mineral resources in the study area. INTRODUCTION This report describes the USBM (U.S. Bureau of Mines) portion of a cooperative study with the USGS (U.S. Geological Survey) to evaluate mineral resources and potential of the Mountain Lakes WSA (Wilderness Study Area), at the request of the BLM (U.S. Bureau of Land Management). The USBM examines individual mines, prospects, claims, and mineralized zones, and evaluates identified mineral and energy resources. The USGS evaluates potential for undiscovered resources based on areal geological, geochemical, and geophysical surveys. Results of the investigations will be used to help determine the suitability of the WSA for inclusion into the National Wilderness Preservation System. Although the immediate goal of this and other USBM mineral surveys is to provide data for the President, Congress, government agencies, and the public for land-use decisions, the long-term objective is to ensure the Nation has an adequate and dependable supply of minerals at reasonable cost.

Jan 1, 1988

By T. J. McDonald

The methods used and the results obtained in the application of high-expansion foam on a recent fire in an operating mine in western Pennsylvania were reviewed. This is the first instance where foam has been applied extensively to a fire under actual mining conditions although considerable research has been conducted and experimental fires have been controlled. The Bureau of Mines began investigating the foam-plug technique in 1957 in its experimental coal mine, following reports of successful trials in Eng-land, where the basic methods, using the normal ventilating current, were developed. Early in the research it was apparent that the normal ventilating current in mines in the United States would not provide adequate air pressure to drive a foam plug the distance that might be required. Subsequently, the Bureau of Mines developed a portable high-expansion foam generating unit consisting of a fan having relatively high pressure potential, net, sprays, and metering equipment. To date, foam generators have been constructed by the Bureau, by at least one operating coal company, and by one manufacturer of safety equipment. A number of units from the latter supplier have been adopted by coal-mining companies as an integral part in their firefighting installations.

Jan 1, 1961

By Nicholas Kyriazi

It is of interest to know how to obtain as high an absorption efficiency as possible from a CO2-absorption canister used in closed-circuit breathing apparatus. In this study the Bureau of Mines found that varying the bed depth and the cross-sectional area of a canister changes its absorption characteristics. In tests using four ,1 rectangular, variable-depth canisters with different cross-sectional areas, the Bureau found that, given a constant weight of the chemical absorbent, LiOH, and a constant COa input, the canisters with a greater cross-sectional area reached C02 levels of 0.5 volume-percent in the effluent gas sooner than did the canisters with a greater bed depth. However, resistance to flow through the canister increases with bed depth, and a trade-off is inevitable. It was anticipated that the efficiency of a canister would increase with increasing intergranular air space approaching the tidal volume of the breathing waveform and then level off at some point under 100 percent. This postulation was partially substantiated. Cylindrical and radial canisters were also tested and compared. It appears that shape is not as important a factor in absorption efficiency as bed depth, since neither canister differed significantly from the rectangular canisters with regard to absorption efficiency values.

Jan 1, 1980