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The XVIth International Conference on Coal Mine Safety Research was divided into eight half-day technical sessions. In accord with the established practice of these conferences, at each session, presentation of the papers was followed by a discussion period. Questions and comments submitted in writing to the session chairman were answered or discussed by the authors of the relevant papers or by their representatives. These discussions were tape-recorded in the original language of the speaker and subsequently translated into English when necessary. Questions to which no answer was available at the time and a few comments that exceeded the scope of the session have been omitted.

Jan 1, 1975

By Nadia C. Miller

In situ metals research to characterize the hydrology of a fractured crystalline rock mass in under-ground mine stopes is discussed. The objective of this study was to find the potential direction, velocity, and concentrations of a lixiviant plume, should leaching solvents (lixiviants) escape from a test stope. The study was conducted by the U.S. Bureau of Mines at the Colorado School of Mines Experimental Mine in Idaho Springs, CO. Since this was a method evaluation site, the lixiviant was simulated using water and acceptable tracers. The site is located in moderately fractured Precambrian migmatite-biotite gneisses of the Idaho Springs Formation. The data required for the characterization were obtained from geologic maps and reports, core logs, and air and water permeability tests. The acquired data were analyzed and applied to a computer model that calculated' the characteristics of a lixiviant plume originating at the stope. A sensitivity analysis showed that dispersivity, ground water velocity, fracture porosity, and fracture spacing had notable effects on the concentration of the plume. Assuming a saturated rock mass, the lixiviant plume would disperse to undetectable levels in a very short time because of a high fracture density at the mine site.

Jan 1, 2010

By John E. Pahlman

The U.S. Bureau of Mines has continued its investigation of chemical additive drilling fluids that produce a zero surface charge (ZSC) on a rock to better define the boundary conditions of the phenomenon. Laboratory drilling tests were performed on Minnesota taconite, Tennessee marble, and Sioux Quartzite using diamond-impregnated coring bits or tungsten carbide spade bits. Drilling fluids were made from chemical additives such as inorganic salts, cationic surfactants, cationic polymers, acids, or nonionic polymers in either distilled, deionized water (DDIW), mine pond water, mine well water, or tap water. These additives were tested below, at, and above their respective ZSC concentrations. Penetration and bit life improvements obtained with ZSC concentration solutions ranged from 88 and 56 pct, respectively, to over 650 pct and over 400 pct, respectively, for the additives tested. Polyethylene oxide (PEO) was found to be the best additive for ZSC-controlled drilling because a continuous range of PEO solution concentrations produced the enhanced ZSC-controlled drilling performance.

Jan 1, 1989

By C. M. Harrer

This paper describes the location, features, qualities, extent, and potential of iron occurrences and some associative resources - limestone and dolomite, coal, petroleum and natural gas, power, and water - in New Mexico. Reconnaissance investigations were made of 118 iron occurrences to determine their extent, attitude, and potential; character samples were analyzed to determine their quality and impurities; and pioneer metallurgical investigations were made on character samples to present their metallurgical problems. Some factors influencing past and potential iron markets are discussed. The most abundant iron minerals are magnetite and hematite, The higher grade deposits are extensive contact-metamorphic and pyrometasomatic replacements in calcareous Paleozoic rocks associated with intrusives. Low-grade deposits of considerable potential are the extensive Cambrian oolitic hematites of sedimentary origin and the Precambrian magnetite-hematite taconite iron formation. Iron occurs also as extensive colluvial and alluvial concentrations. A wide variety of accessory elements are indicated and these pose metallurgical and economic problems.

Jan 1, 1963

By C. M. Harrer

This paper describes the location, features, qualities, extent, and potential of iron occurrences and some associative resources -limestone and dolomite, coal, petroleum and natural gas, power, and water - in New Mexico. Reconnaissance investigations were made of 118 iron occurrences to deter-mine their extent, attitude, and potential; character samples were analyzed to determine their quality and impurities; and pioneer metallurgical investigations were made on character samples to present their metallurgical problems. Some factors influencing past and potential iron markets are discussed. The most abundant iron minerals are magnetite and hematite. The higher grade deposits are extensive contact-metamorphic and pyrometasomatic replacements in calcareous Paleozoic rocks associated with intrusives. Low-grade deposits of considerable potential are the extensive Cambrian oolitic hematites of sedimentary origin and the Precambrian magnetite-hematite taconite iron formation. Iron occurs also as extensive colluvial and alluvial concentrations. A wide variety of accessory elements are indicated and these pose metallurgical and economic problems.

Jan 1, 1963

By Maria I. De Rosa, Charles D. Litton

The National Institute for Occupational Safety and Health (NIOSH/PRL) conducted a series of large-scale experiments to evaluate the effectiveness of optical flame detectors, photoelectric smoke detectors, and combined ionization and photo­electric smoke detectors for rapidly detecting mining equipment cab fires. The detec­tor alarm times were then used to trigger the discharge of a fire inerting system inside the cab to suppress cab material fires. This paper discusses the types of fire detectors tested, the experiments that Were conducted, and the results that were obtained. Con-" elusions are that rapid detection of equipment cab fires can be achieved to trigger the discharge of a fire inerting system inside the cab to protect the operator in the cab.

By Douglas F. Scott

Zinc, silver, copper, and tungsten are the principal minerals in Dardanelles RARE II area (No. 4982). Zinc with associated silver and copper occurs in a persistent shear zone in metasedimentary rocks and in a massive sulfide vein; tungsten occurs as disseminated scheelite in a tactite zone along a metasedimentary-intrusive rock contact. Since 1883, approximately 100 lode mining claims have been recorded, mainly it the eastern portion of area No. 4982 (fig. 1). Extensive workings on the Alhambra Prospect indicate past production; however, no records were found for the prospect. At the Alpine Mine, 500 tons of tungsten ore had been mined before 1943 (Hopson, 1943, p. 1) and possibly 1,000 tons of tungsten ore mined by 1947 (Benson, 194/, pp. 2).

Jan 1, 1982

By Alex C. Smith

This report describes laboratory studies conducted by the Bureau of Mines on the spontaneous combustion of U.S. coals. Approximately 11 pet of U.S. underground coal mine fires are attributed to spontaneous combustion. The relative self-heating tendencies of 24 coal samples were evaluated in an adiabatic heating oven. Minimum self-heating temperatures (SHT's) in the oven ranged from 350 C for a lignite and high-volatile C bituminous (hvCb) coal, to 1350 C for two low-volatile bituminous (lvb) coals. An empirical expression was determined predicting a bituminous coal's minimum SHT in the adiabatic oven based on the coal's dry ash-free oxygen content. Several factors that can affect the self-heating process were also evaluated. The self-~eating tendency of a coal increased when the coal was dried and exposed to humidified air, and was dependent on the particle size and oxygen concentration of the air. A new moderate-scale apparatus is described, in which the self-heating tendencies of larger coal samples, 3 kg, can be evaluated. The minimum SHT's of two coals were determined and the results were in good agreement with those found in the adiabatic oven. Finally, results of a test in the moderate-scale apparatus indicated a strong dependence of the self-heating rate of a low rank coal on the moisture content of the air.

Jan 1, 1987

By James M. Link

Underground coal mining is the most hazardous industrial occupation in the United States.. Haulage accidents in underground coal mines contribute substantially to the occupational hazards of this type of work. In an effort to improve mine safety, a completely hydraulic transport system has been designed to move coal from the mine face to the preparation plant. The capital investment for the hydraulic haulage system is great, and the size of the mine developed for this study is large. Mine production for the conventional haulage mine is 1. 1 million tons of clean coal per year, while the hydraulic haulage mine will produce over 1.6 million tons of clean coal per year. Safety statistics for a number of mines of this size are shown.

Jan 1, 1975

By A. J. Kraemer

This report on research and experimentation by the Federal Bureau of Mines on technologic and scientific problems of the petroleum and natural gas industries presents a resume of work from July 1, 1953, to June 30, 1956. The preceding report, for the fiscal year ended June 30, 1953,3/ indicated continuation of the Bureau's program of petroleum and natural gas research of world-wide significance, which began in 1910. The petroleum and natural gas research of the Bureau of Mines is divided into five main categories: (1) Production of petroleum and natural gas, (2) transportation and storage, (3) petroleum chemistry and refining, (4) thermodynamics, and (5) economics.

Jan 1, 1959

By Richard J. Mainiero, Michael J. Sapko, James H. Rowland III, Marcia L. Harris

All explosive materials produce a cloud of reaction products, the most toxic of which is nitrogen dioxide (NO2). In the study reported here, 4.5-kg (10-lb) charges of blasting agent confined in either thin-wall 10-cm (4-in) diameter galvanized pipe or 10-cm (4-in) schedule 80 seamless steel pipe were detonated in a closed chamber. The detonation gases were analyzed for NO2, nitric oxide (NO), ammonia (NH3), hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), nitrogen (N2), oxygen (O2), and methane (CH4). Data were evaluated to determine the kinetics of the oxidation of NO to NO2. Analysis revealed that the only mechanism for NO loss for the conditions existing in the chamber was the reaction 2NO + O2 6 2 NO2. The rate constant was 2.08 @ 10-38 cm6 molecules-2 sec-1 for the rate equation -½d [NO]/dt = K @ [NO]2 @ [O2] for NO concentrations up to 100 ppm. The rate constant is in agreement with that recommended by Baulch, Drysdale, and Horne (1973).

By G. J. Slavens

The U.S. Bureau of Mines conducted research on preparing submicrometer titanium nitride (TiN) powder as a substitute for tungsten carbide (WC) in cutting tools and wear-resistant parts. Earlier research on a small scale was expanded to include a larger reactor. The TiN powder was produced by contacting titanium tetrachloride (TiCI4) with anhydrous ammonia (NH3) in the presence of Mg at 1,100° C. The powder was collected in an electrostatic precipitator (ESP) filled with ultra-high-purity (UHP) Ar. All collected powder was thermal vacuum distilled to remove Mg and magnesium chloride (MgCl2), leaving the purified TiN. Powder handling and purification procedures were conducted to assure low oxygen content in the powder product. Oxygen content in the distilled TiN powder product was as low as 0.40 wt pct. Nitrogen averaged near 22.0 wt pet with a high of 22.4 wt pct. The purified powder product had an average median particle diameter of 0.14 µm with a standard deviation of 0.09 µm.

Jan 1, 2010

By Frank C. Townsend

Waste disposal schemes using spent shale in embankments require a thorough knowledge of its geotechnical engineering properties for environ-mentally safe disposal. In this context, the objective of this laboratory investigation was to determine the physical properties, geotechnical properties, and composition of spent oil shale retorted by the PARAHO and TOSCO processes. Physical properties consisted of mechanical analyses, Atterberg limits, and specific gravity determinations. Geotechnical engineering properties were determined by compaction, maximum-minimum density, unconfined compression, triaxial compression, permeability, direct shear, Ko, cyclic tri-axial, resonant column, and Los Angeles Abrasion tests. Petrographic, chemical, and scanning electron microscopy analyses were used to determine compositional features. Unprocessed shale is hard and durable and more properly described as a carbonate rock instead of shale. PARAHO is classified as a GP, while TOSCO classifies as an SM. PARAHO requires no moisture for compaction to maximum densities; however, TOSCO does. Retorting causes a loss in durability but creates self-cementing characteristics, which for PARAHO a 3-to 8-fold strength increase was observed, while for TOSCO the increase was 1.5 to 3 folds. The shear strength, compressibility, and dynamic properties of compacted PARAHO are comparable to those for sandy gravels. Compacted PARAHO is semipervious, while compacted TOSCO can be semipervious to impermeable.

Jan 1, 1979

During the second quarter of 1983, the economic recovery showed further strength abetted by the performances of consumer spending, residential investment, and the slowing down of inventory reductions. Real gross national product (GNP) increased from the first to second quarter at an annual rate of 9.2 percent, compared with 2.6 percent from the fourth quarter of 1982 to the first quarter of 1983 and an overall 1.9- percent decrease in 1982. Total industrial production increased 1.8 percent in July, and productivity as measured by output per man-hour increased 1.3 percent between 1982 and the first quarter of 1983 (table 1). Especially noteworthy .was the performance of real consumer durable goods expenditures, which increased at an annual rate of 32.0 percent from the first to the second quarter (about half of the increase consisted of automobile sales) and real consumer spending, which increased between these periods at an annual rate of 9.7 percent. Residential investment increased at an annual rate of 76.1 percent between the first and the second quarters,1/ and private housing starts by about 38,000 units in both March and May.

Jan 1, 1983

By C. M. Harrer

The location, features, qualities, and extent of iron occurrences and the associated resources--limestone and dolomite, bentonite, coal-lignite, petroleum and natural gas, power, and water--are evaluated. The results of pioneer beneficiation tests on South Dakota taconite are discussed. In addition, pertinent features of taconite development, cost factors, the Western and Central United States trade area and markets are reported. The State's production of iron ores until 1963 has been small and for purposes other than the manufacture of iron. This investigation disclosed the probability of large resources of taconite in Pennington and Lawrence Counties. The average iron content is 29 percent, and a 65-percent or better iron concentrate might be produced. Ample resources are available for mining and processing taconite. An investment of at least $26 million would be required for a plant capable of turning out 1 million tons of agglomerated iron concentrate per year. The feasibility of such an enterprise is indicated, but intensive investigation and research must be completed to justify such an investment.

Jan 1, 1966

By Milford L. Skow

This report summarizes the principal activities and results of 15 years of research by the Bureau of Mines, U.S. Department of the Interior, on methane control in coal mines. This research has investigated fundamental factors regarding the occurrence and movement of methane in coal beds, removal of methane prior to mining, and control of methane during mining. The report includes a bibliography listing the more than 150 publications resulting from the Bureau's methane control program as well as numerous other references, a section on methane recovery and use, a look at the upcoming Bureau of Mines research program, and a brief review of methane drainage practices in other coal-producing countries.

Jan 1, 1980

By Clarence A. Wright, JAMES T. NORTON, JAMES G. PARMELEE

The object of this paper is to give to mining companies and to all others who are interested some idea of the possibilities in the treatment, by differential flotation, of lead-zinc ores of the Coeur d'Alene region and other districts. The purpose of these investiga.. tions is not to evolve a differential flotation process that would replace present methods of gravity concentration but rather one that could be applied to the relatively fine material and slime produced in the mills and treated unsuc_pessfully by gravity methods or by flotation. It is expected, of course, that the products to be obtained by differential flotation would be of much better grade than those now produced by flotation in the Coeur d'Alene mills. In view of the fact that it has been difficult to obtain representative samples of flotation feed from the mills, owing to the necessity of shipping the material wet and free from oil or other foreign matter that might be deleterious to the differential separation of the sulphides, the writers have felt justified in running flotation tests with the mill feeds in order to ascertain whether a differential separation of the sulphides could be effected. However, two different lots of flotation feed were tested for differential flotation, and the results of tests of one of these are given in this report. It is hoped that it will be possible later to test out the flotation feed for differential flotation on a large scale in some of the mills. This paper covers part of the investigations carried on by the United States Bureau of Mines in cooperation with the Idaho Bureau of Mines, the University of Idaho, and certain mining companies of the Coeur d'Alene region. Although the results of the tests included in this report are not to be considered final, they indicate possibilities and may suggest others leading to a solution of the problem of separating lead and zinc sulphides by differential flotation in the treatment of certain ores.

Jan 1, 1921

By Thomas M. Barczak

Roof support technology for longwall tailgates has changed dramatically during the past decade. Filling tailgates with conventional wood cribs is becoming the exception rather than the rule. Modern engineered timber support systems and a host of other alternative support products provide far greater capacity as well as stiffer response, thereby allowing the supports to resist roof movement with much less displacement than the soft wood cribbing used in the past. For these reasons, these products can provide superior roof control. In addition, the material handling requirements for support installation have now become a major consideration in the support design and selection process. Products such as conventional wood cribbing that require piece-meal construction of bulky, heavy components have diminished, while prop-type supports and products that can be installed with machinery and pumpable support technologies have grown in use resulting in fewer injuries to mine workers. Now, the opportunity exists to provide the safest, most cost effective support system, through engineering design rather than by trial and error and to optimize the use of the support system chosen. Yet this is rarely done. The key to accomplishing this task is to understand the interaction of the support system with the ground conditions at the installation site. A major focus of the paper is to conceptualize the support and interaction through the use of a ground reaction curve which relates the support resistance to the convergence of the longwall tailgate. The goal of any roof support design is to control the ground deformations and maintain the structural integrity of damaged or broken ground to the extent possible to provide a stable mine opening. In general, deformations will be a function of the stress environment and inherent strength of the surrounding rock mass. However, if the deformations are intimately linked to the stress changes such that the deformation can be controlled by the load resistance or reinforcement provided by a roof support system, then the loading behavior can be described as load-controlled. Conversely, if the deformation occurs irrespective of the installed support (assuming practical limitations), then the loading behavior is described as displacement-controlled. In this case, the deformation can be considered irresistible from a practical standpoint. In this context, the nature of the loading has significant consequences on the support design requirements. Finally, examples using the NIOSH Support Technology Optimization Program (STOP) to develop design criteria using ground reaction data from underground studies and ways to include uncontrolled convergence as part of the design criteria for standing roof supports will also be discussed.

By R. F. Abernethy

Recent investigations in the United States and in other countries have produced considerable information on the nature and occurrence of minor elements in coal. The possibility of recovering certain elements, particularly germanium and uranium, from coal ash and other coal products has received considerable attention. Some flue dusts are potential sources of germanium, and certain lignite deposits are potential sources of uranium, but industrial recovery of these elements has been limited to small quantities for technical and economic reasons. Considering the large amount of coal mined annually, a small percentage of a rare element may have industrial significance if an economical method of recovery can be developed. In 1944 information on the occurrence of rare elements in coal was reviewed in Bureau of Mines Technical Paper 669 (46).3 This report is a revision of that paper with the view of summarizing published information available for United States coals, and pertinent information concerning coals of other countries. Selected references from the original paper are retained. New references do not include all preliminary reports when more permanent literature describing complete projects is available. Consequently, the list of references should not be considered complete.

Jan 1, 1963

Coal research and related activities in 1964 by the Bureau of Mines resulted in many advances in the production, preparation, and utilization of this valuable natural resource. Mining research during the year was marked by work on hydraulic mining, coalbed degasification, mine drainage control, mine sealing, strip-mine rehabilitation, and quenching of mine-refuse fires. Bureau research continued to produce information leading to increased safety in underground mining. Such research included roof and rib control via bolting and bonding, pressure monitoring of coal and mine rock during mining operations, and development of safety devices for detecting conditions leading to roof falls. Other safety work was continued on methane detectors, coal-dust suppression, and mine ventilation equipment and techniques. Mine explosion and explosives research, mine equipment and materials, safety rule modernization, and safety education and training of mine workmen were continued. Coal storage and preparation work in 1964 ranged from freezeproofing of lignite for rail shipment, through washability studies of coals and washing equipment, to research on new ways to remove ash and sulfur from coal. Electric power production, which accounts for a major portion of the market for coal, received further study. Unique power generation systems, including coal-burning gas turbine and megnetohydrodynamic generators, were intensively investigated. Conventional power systems were improved through continuation of work on furnace performance, powerplant stack gas purification, and engineering and boiler water service.

Jan 1, 1965