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By Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface metal/nonmetal mining categories during 1990–2001 by state and six successive 2-year time periods. Injury risk rates are derived, and ignition source, methods of detection and suppression, and other variables are examined. Fires involving contractors are also included in the analysis. The data were derived from Mine Safety and Health Administration (MSHA)mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and an increased awareness aimed at preventing and reducing fire hazards. It will also form a basis for future fire research programs.

Jan 11, 2004

By Steven J. Page

The increasing concern for dust control in metal and nonmetal mining prompted the Bureau of Mines to investigate the dust suppression technique of applying foam to face drilling and crushing operations in a gypsum mine. Previous attempts to achieve effective dust control on face drills using other techniques, such as dry collection and boom-mounted external water sprays, have not been successful. The largest problem encountered when using these techniques has been the lack of sustained effective dust capture at the face. Results for two faces studied show that injection of the foam through the drill steel provided an average dust reduction of 95 pct. However, the use of foam on the crusher provided no dust reduction at the operator's position (because of good local ventilation) and a 27-pct average dust reduction for two feeders at a location midway between the operator's position and the crusher. The conclusions obtained from this study are that (1) foam can be an extremely effective dust control technique when used on localized dust sources such as dust generated within a blasthole during drilling, and (2) foam is only marginally effective as a dust control technique when used on nonlocalized dust sources such as dust generated during the feeder-and-crusher operation.

Jan 1, 1981

By G. W. Jones, R. E. Kennedy

A simple , quick, and relatively accurate device is needed for determining the presence of very small concentrations of organic halide gases in various atmospheres . Such a device would enable safety engineers , health officials , and others to discover quickly the presence of these gases in a suspected atmosphere and thus be able to apply protective measures promptly. This detector should prove useful in detecting leakage of halide gases from refrigerating and air - conditioning systems and in determining the presence of halide solvents in the atmosphere of dry - cleaning and degreasing establishments where organic halide solvents are used . Virtually all poison war gases are halide compounds . Because of the high toxicity of these gases , even in very low concentrations , a detector having the proper sensitivity should be useful in civilian defense for determining when atmospheres are relatively free of poison gases .

Apr 1, 1943

By S. D. Sanders

Goals of the Bureau of Mines include utilizing readily available minerals as substitutes for scarce mineral commodities and minimizing occupational hazards associated with mineral processing occupations. Therefore, the Tuscaloosa Research Center investigated using rapid-set cement as a suitable molding sand binder for small ferrous castings; currently petroleum-based binders are used. Substitution of a rapid-set cement would eliminate organic vapors associated with the petroleum-based binders; these vapors constitute occupational hazards and environmental pollutants. A binder containing 60 percent white portland cement (WPC) and 40 percent calcium aluminate (CA) would be an acceptable and economic substitute for petroleum-based binders where the foundry requirements are compatible with its limitations. It produced a set time and a pattern strip time of less than 1 hour. Cement, sand, and water mixtures developed compressive strengths from about 40 to 75 psi after 2 hours and from 120 to 130 psi after 24 hours. Tensile strengths of 18 to 22 psi were obtained after 2 hours, increasing to 30 to 35 psi after 24 hours. The addition of about 1 percent polyphosphate to the sand-cement-water mixture doubled the compressive strength and increased the tensile strength about 50 percent after 4 hours, but also increased the set time from 30 minutes to 1 to 1-1/2 hours. Po1yvinylacetate (PVA) resin latex additions resulted in rapid strength development. When castings were poured into the cement-bonded molds, the surface finish was fair to good on gray iron castings, but some areas of burn-on were present on steel castings. Using a graphite wash on the cement-bonded molds produced good surfaces on gray iron castings.

Jan 1, 1979

By T. W. Beck

The National Institute for Occupational Safety and Health (NIOSH) conducratory and field tests to evaluate the effectiveness of dust collector bags for reducing dust liberation and operator exposure from a roof bolter’s dust collection system. The laboratory tests evaluated the bag’s effectiveness to contain dust and the effect on canister filter loading in both a bag and bagless condition. The dust emissions from the collector’s exhaust were also measured in each condition during laboratory testing and show that nearly 100% of the test dust fed into the collector was captured by the dust bags. Loading and pressure drop on the dust collector’s canister filter is greatly decreased when using the bags, enabling longer periods of drilling without filter removal/cleaning. The field results showed that, even though dust standards were met, respirable dust in exhausted emissions was reduced around the bolter. Laboratory and field results show that benefits from use of the bags are realized in all areas of operator exposure.

By Thomas M. Barczak

This U.S. Bureau of Mines study evaluates factors that influence longwall support and strata interaction. The longwall system is composed of an immediate and main roof structure and three supporting foundations: longwall panel, powered roof supports, and gob waste. The main roof forms a structure that is generally supported by all three foundations, while the immediate roof acts as a beam that cantilevers from the coal face to the powered support. In most cases, shield loading involves a complex interaction of both main roof and immediate roof behavior and is a combination of loads produced from convergence of the main roof and displacements of the immediate roof caused by deformations of the cantilevered roof beam. Since the shield stiffness remains constant for all leg pressures and main roof convergence is irresistible in terms of shield capacity, the shield must be able to control the behavior of the immediate roof or floor structure for shield loading to be sensitive to setting pressures. If the goal is to minimize total shield loading, any active setting force must be offset by reduced passive shield loading to justify the active setting loads. Field data sumest that the typical reductions in passive loading do not justify the required increases in setting pressure in some applications.

Jan 1, 2010

By S. D. Maksimovic

The Bureau of Mines evaluated the hydraulic stimulation of a gob-degasification borehole to determine if this procedure would aid in degasifying a longwall panel. The stimulated borehole did not degasify the longwall panel as expected either before or after mining of the panel started. It reduced the underground methane emission only 11 pct, considerably less than the reductions effected by two unstimulated boreholes in the same panel. Some probable reasons for the reduced methane flow from the hydraulically stimulated borehole are very low reservoir gas pressure, location of hydraulically stimulated zones within the grouted casing, a casing break caused by lateral shifting, possible vertical movement of rock strata during caving, grouting of a 4-inch pipe blocking three stimulated zones, plasticity of shales, and possible hole damage by swelling of water-sensitive minerals. The borehole was also located between two second-mined areas, which may have allowed partial degasification of the overburden and the coalbed in advance of mining. Finally, a period of 3 months is probably not long enough for the borehole to degasify the overburden before mining.

Jan 1, 1977

By A. Visnapuu

High-grade synthetic rutile has been produced in the laboratory from domestic ilmenite concentrates by a new carbonyl process. The ilmenite was first reduced to convert the iron oxides to metal and then treated at temper-atures over 1000 C in high-pressure carbon monoxide (CO) to convert the iron to the pentacarbonyl. Rapid carbonylation was achieved in the presence of small quantities of selected promoters. Maximum iron removal occurred at temperatures between 110° and 130° C at CO pressures from 1,000 to 1,400 psig. Iron pentacarbonyl appeared as liquid and vapor in the reactor and could be removed by gravity flow and vapor transport. More than 90 pct of the iron was extracted in 2-hr experiments at pressures of 1,000 psig and above. The Ti02 product is porous owing to the removal of the iron, has the rutile crystal structure, and is suitable for chlorination. Waste disposal problems associated with the process would be minimal because the iron pentacarbonyl can be decomposed to produce iron powder or pellets for sale and CO for recycling.

Jan 1, 1973

By M. J. Kovalik

Illinois No.6, a high-volatile B coal of low fluidity, was blended with fluidized-bed char and coke breeze to improve the strength of the coke obtained from carbonizing this coal. Twenty-one tests, selected from those made in the small-scale Hanson carbonizer, were carbonized in the BM-AGA 13-inch-diameter, cylindrical retort, with a coal charge of about 90 pounds; the strength of the cokes was determined by the standard ASTM tumbler test. Using the same procedure, 10 tests were made with High Splint, a high-volatile A coal from Harlan County, Ky. Carbonization of the blends produced larger and stronger cokes than did the Illinois No.6 coal singly. The optimum blend contained 6 percent each of char and coke breeze. Further improvement in coke strength was realized by either preheating this blend prior to carbonization or by adding a small pro-portion of a premium blending coal. The former method could possibly eliminate the use of premium coking coals in blends with Illinois No. 6 coal to make an acceptable metallurgical coke. Except for no improvement in coke strength by preheating, results for High Splint coal showed behavior similar to that of the Illinois No.6 coal.

Jan 1, 1973

Determine the extent to which remote-sensing techniques, primarily lineament analysis, can be used to identify geologic structures that may affect the location and migration of subsidence over abandoned underground coal mines in the Colorado Springs, CO, area. Compile data using a geographic information system (GIS) to allow efficient and reproducible comparisons and analyses. Background The basis for evaluating abandoned mine land (AML) sites with remote-sensing techniques comes from past and ongoing Bureau ground control research using remote-sensing data to identify potential hazards caused by geologic structures (faults, joints, etc.) above active underground coal mines. Research showed that lineament (linear feature) analysis of Landsat Multispectral Scanner (MSS) images could indicate locations of fractures and fracture trends that had varying, but significant, impacts on the stability of mine openings. Such geologic structures should be identifiable over abandoned mines as well. If fractures are present, even if they arc not faults, they should represent areas of potential instability over these mines and, therefore, should tend to localize subsidence when it occurs, particularly for deep and moderately deep portions of mines.

Jan 1, 1992

By Guy A. Johnson

The Bureau of Mines, through research and development contracts with the FMC Corp., has developed and tested two automatic fire sensing and suppression systems for large haulage vehicles. This work was undertaken to enhance driver safety, to lessen substantial property damage from fires on large trucks, and to increase the vehicle operator's productivity. One automatic truck fire protection system protects both the engine compartment and brake rid areas, while the second system is used in the engine compartment and fuel tank area. Both systems have redundant fire-sensing capabilities and manual override controls. Upon sensing flames and/or heat, the systems suppress the fire with pressurized, E-C class dry chemical. Both fire protection systems are flexible in design and can be modified for use on other mobile minim' equipment. Prototypes of both systems have been subjected to long-term, in-mine validation testing and actual Eire tests on 100-ton-capacity trucks at the Puma mine near Tucson, Ariz., and the Erie mine at Hoyt Lakes, Minn. During the 4-month endurance test of the first system at Pima, an accidental flash fire occurred in the test truck while it was working in the pit. The system successfully sensed and automatically extinguished the fire with no injury to the driver and little damage to the truck.

Jan 1, 1975

By James H. Aase

Selected glacial lake clay deposits in Minnesota were sampled, tested, and evaluated to determine their suitability for use as a bonding agent in iron ore pellet manufacturing. Preliminary tests conducted on clay samples obtained from five ancient glacial lake basins identified the clays in the Lake Agassiz glacial lake basin near Cook, Minn., as having the greatest bonding potential. An auger drilling program was conducted to obtain substantial quantities of representative material for detailed testing. The drilling indicated the presence of large clay reserves in excess of 500 million tons within the 12-square-mile area investigated. Bench scale tests indicated that the bonding properties of Cook area clays, when activated with relatively small quantities of sodium carbonate monohydrate (Na2C03?H2O), imparted excellent strength characteristics to iron ore pellets. Larger scale continuous pelletizing tests were made to confirm the bench scale results. These tests indicated that use of 1 percent activated clay alone as binder gave the iron ore pellets an overall strength slightly lower than with 0.75 percent bentonite, considered the industry standard. Use of 0.5 percent activated clay plus 0.5 percent bentonite produced better pellet strength qualities than use of 0.75 percent bentonite alone, without increasing the silica plus alumina content. The data from both bench scale and larger scale continuous tests suggest that the Cook, Minn., clays can be utilized after activation either alone or in combination with bentonite at an economic advantage over present pelletizing practice with bentonite.

Jan 1, 1968

By J. Feldman

This report contains a description of the distillation laboratory at Bruceton, Pa., which was established to aid in the separation and identification of the products produced in the synthetic liquid fuel processes under study there. Compounds present in synthetic liquid fuels may include aliphatic from C1 to C60 or greater. Alcohols, ketones, esters, aliphatic carboxylic acids, saturated hydrocarbons, olefins, and diolefins are all found in Fischer-Tropsch products. Coal-hydrogenation products contain, in addition to aliphatic compounds, a large proportion of naphthenic material and aromatic compounds ranging from benzene to coronene; in addition, appreciable quantities of tar bases and tar acids are present. In designing the laboratory, therefore, provision had to be wade for the greatest amount of flexibility and versatility. A great deal of standardization of basic equipment had also to be designed to permit interchange of parts and services.

Jan 1, 1951

By Richard F. Hewlett

The mining industry utilizes a vast store of knowledge, wisdom, and engineering talent in designing mining systems. However, the complexity of the required systems and the presence of numerous variables frequently necessitates raking important decisions without having adequate accurately detailed information. That many of the decisions made in the past were nearly correct, in the long run, is substantiated by the number of successful mining enterprises that exist in the world today. Subsequent to 1940, the disciplines of operations research and systems engineering were developed. The disciplines have produced methods of providing better information to persons responsible for making decisions.

Jan 1, 1963

By T. E. Sterner

A laboratory investigation was conducted to determine the applicability of the thermal oil-recovery method as a means of increasing ultimate oil recovery in the Appalachian region. The primary objective was to establish self-sustained combustion in consolidated and unconsolidated sand test assemblies saturated with various amounts of Pennsylvania Grade crude oil and synthetic brine. Tests using blocks of sandstone were unsuccessful because of sealing problems and fracturing of the rock due to thermal stresses. A combustion wave of about 700° F was propagated through the sand-oil-water packs in the linear tube tests. The high air flux used resulted in high oil consumption and rapid movement of the combustion wave through the tubes. Analytical tests on the sand pack showed that sufficient fuel was deposited during the linear tube experiments for a self-sustained combustion wave.

Jan 1, 1967

By George H. Schnakenberg, Aleksandar D. Bugarski

This report reviews the performance and applicability of technology for the control of emissions from diesel-powered equipment used in underground coal and metal/nonmetal mines. The methods discussed include Mine Safety and Health Administration-approved low-emission engines, engine derating, fuels, fuel additives, diesel oxidation catalysts, and diesel particulate filters. The potential of each of these technologies is examined individually and in combination. The performance estimates are derived from the published literature and presented in narrative and Tabular form. The purpose of this report is to help the mining industry select the most appropriate method to reduce underground exposures of miners to diesel exhaust in the context of the recently developed diesel regulations. It is important to note that the control technologies discussed in this report have received limited evaluation in underground mines. Additional research is ongoing, and some engineering design changes may need to be implemented before all of these diesel emission control technologies can be safely and successfully used in underground mines.

Jan 1, 2002

By Jalna R. Zatko

The Bureau of Mines, U.S. Department of the Interior, has developed a novel method of flocculation dewatering of phosphatic clay wastes using polyethylene oxide as the flocculant. Research was conducted to determine whether ethylene oxide gas was present in the air in the vicinity of disposed waste materials which had been flocculated with polyethylene oxide. Samples of clay waste materials containing polyethylene oxide were prepared in stoppered glass bottles in simulated disposal environments. Gaseous samples, removed over a 75-day period using an airtight syringe, were injected into a gas chromatograph that was capable of separating ethylene oxide from air. The presence of ethylene oxide gas was not detected in any sample. To determine possible degradation products of polyethylene oxide, the properties and reactions of ethylene oxide and its polymers were reviewed. Based upon the literature survey and experimental study, it was concluded that adverse environmental effects were not likely to result from the use of polyethylene oxide for flocculating phosphatic clay waste products.

Jan 1, 1980

By F. N. Kissell, H. K. Sacks

This study examines the accuracy of area sampling for measuring the dust exposure of mining machine operators in coal mines. The specific objective of this research was to find locations where an area sampler might work better than earlier studies have indicated. The results show that fixed-location area sampling cannot accurately predict the dust exposure of a machine operator, even when the best fixed location is sought, the fixed location is quite close to the operator and the bias due to the dust concentration gradient is corrected. Industrial hygienists have known for many years that area sampling is unsuitable for measuring air contaminant exposures in the workplace. Near contaminant sources, the dilution air and the contaminants are not evenly mixed. Therefore, when workers are near contaminant sources, exposure measurements must be taken from the worker's breathing zone to be accurate

As a basis for recommendation and for instruction of bureau engineers the considered opinion of the bureau is expressed in "decisions" of its Mine Safety Board, approved by the Director. Ten of these decisions were discussed, in Information Circular 6091.3 Decision No. 11, approved by Scott Turner, Director, on February 28, 1929, is as follows: "In the interest of safety, the Bureau of Mines, Department of. Commerce, recommends that in coal mines, haulage and (or) hoisting be kept in intake air as far as possible." As in the case of previous mine-safety decisions, the subject matter covered by this decision has frequently come to the attention of the Bureau of Mines through the reports of its mining engineers on explosion disasters and in accident-hazard investigations.

Jan 1, 1929

By Daniel W. H. Su, Gregory J. Hasenfus

This paper demonstrates that finite-element modeling can be used to predict in situ coal pillar strength, especially under non ideal conditions where interface friction and roof and floor deformation are the primary controlling factors. Despite their differences in approach, empirical, analytical, and numerical pillar design methods have apparently converged on fundamentally similar concepts of coal pillar mechanics. The finite-element model results, however, are not intended to suggest a new pillar design criterion. Rather, they illustrate the site-specific and complex nature of coal pillar design and the value of using modeling procedures to account for such complex site-specific conditions. Because of the site-specific nature of coal pillar design, no single pillar design formula or model can apply in all instances. Understanding and accounting for the site-specific parameters are very important for successful coal pillar design. More work remains before the century-old problems related to pillar design are finally solved. Future research should focus on the cross-linkage of empirical, analytical, and numerical pillar design methods.

Jan 5, 1999