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By John T. Dieckmann

This report documents the work performed and the results obtained in a 2-year development of a Mobile Inert Gas Generator for use in the Bureau of Mines Remote Sealing System for fighting underground coal mine fires. The performance requirements of an inert gas generating system for the Remote Sealing System were clearly established. A thorough review of seven possible system designs meeting these requirements was conducted. An air cooled, distillate oil fired combustion type inert gas generator was selected for further detailed design, hardware fabrication, and performance testing. The Inert Gas Generator constructed under this program has been thoroughly performance tested and has been operated in the field for approximately 200 hours. The system has met or exceeded all important performance requirements. The system was used in the fire fighting efforts at the Bethlehem Mines Corporation Cambria Division Mine 33 fire and contributed to the successful containment of the fire. The system was also employed in the demonstration of entire Remote Mine Sealing System at the Jenney Mine in the fall of 1978. The system is currently avail-able for fighting any future underground coal mine fires.

Jan 1, 1979

By Philip A. Mattson

INTRODUCTION Engineers involved with rock mechanics know the importance of discontinuities within a rock mass and their effect on its behavior when subjected to loads from structures or construction excavation activities. Various geophysical tools have been developed to provide comparative information on subsurface conditions, such as electrical resistivity, assorted seismic test methods, acoustic tests, etc. While these investigative means have proved invaluable in numerous situations, especially those where site alternatives are being evaluated, they shed little light on the difficult problem of quantifying the rock strength. For that purpose, a laboratory test program of samples obtained in the field is usually undertaken, often in conjunction with a variety of in-situ tests. While standard samples provide sufficient information on the rock properties, questions on the macro-structure of joints, faults, fissures, and their infillings often go unanswered. Presently, attempts are being made to incorporate into rock sampling technology new techniques which are directed towards providing better information on the incidense and orientation of discontinuities. One such device incorporates a scribe knife within the core barrel which scores the sample lengthwise as it is cored. The orientation of the scribe is known, thereby relating the bedding, planes, fractures, etc. to a spatial framework. A second approach, called the Integral Sampling Method, is the subject of this paper. Stated briefly, this method utilizes a grout injection to bond fractured rock to a steel reinforcing bar at the center of the coring. The bar is intended to act as a

Jan 1, 1979

By Rodney K. Morrison

MARTA, The Metropolitan Atlanta Rapid Transit Authority, is building a 53 mile heavy rail transit system to serve the City of Atlanta. Phase A of the Rail System, consisting of approximately 14 miles of at-grade, aerial and subway construction is underway. Metropolitan Atlanta lies in the Piedmont Geologic province of Georgia and is underlain by rocks of essentially granitic and gneissic nature. The soils encountered are primarily silty sands which are in-place weathering products of the parent rock and exhibit their relic structure. In general, these materials have presented no unique construction problems other than those created-by proximity of manmade structures, local availability of ground water, and top of rock elevation. The subway sections of primary interest in this paper consist of hardrock and soft ground tunnels and extensive cut-and-cover sections. The cut-and-cover construction includes excavations as deep as 80 feet. Temporary support systems in these deep excavations consist of soldier pile-timber-lagging or soldier pile-tremie concrete (SPTC) walls with internal bracing or tiebacks. In shallow cut-and-cover sections, where right-of-way economics permitted, slopes were laid back partially or fully to reduce or eliminate the need for bracing systems. Dewatering systems were required in most open cut excavations. Due to the close proximity of utilities and existing structures to the MARTA

Jan 1, 1979

By J. Hanslovan, R. H. King

An investigation of the feasibility of shielding low-voltage trailing cables in underground coal mines is described. Both laboratory and under¬ground installation results are presented. The main objective of shielding is to reduce the electrical shock hazard; however, several problems will be encountered by mine operators who install shielded cables. Parameters related to such items as purchasing, splicing, troubleshooting, safety, and reliability are discussed. Some of these problems can be minimized by changes in cable constructions and shuttle-car reeling-device components. Both SH-C and SH-D constructions are considered.

Jan 1, 1979

By R. A. Pond

Two 6.17 m (20 ft 3 in.) diameter raises, concrete-lined to 5.49 m (18 ft) inside diameter, were completed in 1978 at the Monterey Coal Company Number One Mine near Carlinville, Illinois, by Frontier-Kemper Constructors. These two raises are the largest in cross-section yet completed by full-face upreaming, and the success of this project is expected to increase the application of raise-boring to coal mine shaft construction. WHY 6.17 M (20 FT) DIAMETER ? Raise boring is well accepted in the metal mining industry for a variety of applications, and is gaining in acceptance in the civil works construction industry. The use of raise boring to construct vertical openings for coal mines has not been as widely accepted, even though coal mining requires, per mine, the greatest number of openings to the surface of any underground activity. Several factors have influenced the low utilization of raise boring in coal mining: 1. Coal mine shafts must often be of large diameter to pass the required high volumes of ventilation air at acceptably low water gage pressures. Cross-sectional areas of finished shafts exceeding 23.23 sq m (250 sq ft) are common. 2. The life of ventilation shafts is comparatively long, and the typical sedimentary strata overlying coal seams normally require that the shafts be lined. Shafts on the intake ventilation circuit must have permanent water-tight linings. 3. Unconsolidated overburden at the surface is often thick, and as reaming cannot be safely utilized in unconsolidated material,

Jan 1, 1979

By I. S. Thompson

A program of geochemical till prospecting, carried out by Derry, Michener & Booth in 1974, was instrumental in t~ e discovery of a copper deposit in Currie Township, Ontario, beneath thick lacustrine deposits of the Abitibi Clay Belt. The prospecting system involved the continuous collection of glacial sands and gravels beneath the clays, using a track-mounted, dual-tube rotary drill, and the separation and geochemical analysis of the heavy mineral content for Cu, Zn, Pb, Ag and Au. In one of 22 holes drilled down-ice from nine Canadian Nickel airborne EM conductors, fragments of chalcopyrite-bearing graphitic argillite, assaying 12% Cu, were recovered from a 14-foot gravel section beneath 83 feet of clay. Ultimately, mineralization was identified in 10 of 11 additional holes drilled up to 3,000 feet down-ice from the Currie deposit. The glacial fan, when compared to the 1,200- by 165-ft area of the subcropping mineralization, is at least 20 times the area of the deposit and is the result of glacio-fluvial reworking of the mineralized ground moraine. The Currie deposit is contained within a Keewatin succession of graphitic argillite, dacite tuff and graywacke, which is intruded by dacite and feldspar porphyry sills and dykes and truncated by a Keweenawan diabase dyke. Grade and thickness of the mineralization, which lies chiefly within the argillite, is related to felsic intrusives and hydrothermal alteration, and to fold hinges.

Jan 1, 1979

By R. C. Butman

The Lincoln Terminal System (LTS) is a stand-alone computerized training device that presents high quality visual displays, and audio messages to a student. A keyboard is provided for student input. A variety of student-machine interactive programs arc provided. These programs allow the author/instructor to evaluate numerical entries and responses to simple and compound multiple-choice questions (where a compound choice is defined to be more than one choice, ordered or unordered from one or more list(s) of choices. Descriptions of LTS applications, lesson development procedures, hardware provided and support facilities required are given. A contract history summary, and a bibliography of reports published under three successive BoM contracts supporting LTS development, is provided.

Jan 1, 1979

Presiding was Robert E. Murray. The first speaker was Frank L. Natta, Administrative Manager-Trapper Mine, Utah International, Inc., Craig, Colorado. Subject - "Long Term Coal Contracts." Mr. Natta graduated in 1973 from Colorado School of Mines with a B.S. in Metalurgical Engineering and a M.S. in Mineral Economics. Since 1974, he has been employed by Utah International having spent 5 years in San Francisco as Senior Market Analyst. In this capacity he was responsible for market development efforts for Utah's U. S. coal reserves. Recently, he was transferred to Craig, Colorado, as Administrative Manager of Utah's Trapper Mine. In this position, he is responsible for purchasing, warehousing, accounting and sales contract administration. The second speaker was Brucks Mitchell, President, Human Resources Management, Inc. Richardson, Texas. Subject-"Making Unions Unnecessary in the Coal Industry." Mr. Mitchell has a B.A. degree in English-Oklahoma State University. M.B.A. degree in Organizational Behavior-Southern Methodist University. Ph.D Candidate - Organizational Behavior - North Texas State University. Mr. Mitchell formed an Association of Consultants to perform assignments in Industrial Psychology and Human Resources Management. Particular emphasis has been to establish policies and procedures to make labor unions unnecessary. He has been consultant to various industrial and municipal organizations.

Jan 1, 1979

By Charles D. Litton

An overview of state-of-the-art technology in fire detectors is presented by the Bureau of Mines regarding their use in the mining industry. Detectors are categorized according to the characteristics of a fire to which they respond. Operating principles of the various detectors, their application, and the advantages and disadvantages of each are discussed.

Jan 1, 1979

"10.1. IntroductionAs discussed by Westland (1981), the six platinum-group elements (PGE) belong to the Group VIII transition metals, to which iron, nickel and cobalt also belong. The chemical similarity between these nine metals accounts for the fact that they tend to be concentrated together as a result of geological processes. These processes started to effect the distribution of these metals at the very beginning of the earth's history.The first line in Table 1 gives the concentration of nickel and certain other Group VIII transition metals in carbonaceous chondrites, those meteorites with a composition that is believed to reflect best the composition of our planetary system apart from hydrogen and helium. The second line is the estimated concentration of the same elements in the earth as a whole. It is seen that these two estimates are quite similar, the earth being perhaps 2 to 3 times richer in these particular metals than the planetary system as a whole. The reason for this is not fully understood, but it may be due to the earth being formed by the accumulation and capture of a greater proportion of iron (and therefore siderophile-rich) than stoney (and therefore siderophile-poor) planetesimals than the planetary system itself.The third line in Table 1 is the average composition of the crust of the earth. With the exception of iron, all of the Group VIII transition elements are rare in the crust, present at concentrations of It tOO to Itt ,000 of that of the bulk earth. This is because the outstanding chemical characteristic of this group of elements is their siderophile nature; that is, their tendency to alloy with metallic iron. Because of this, once the earth became molten very early in its life history, these elements dissolved in the molten iron present at this stage and were removed from the outer accessible parts as this dense liquid sank to the centre of the earth to form the core. Although iron was the main instrument of concentration of the Group VIII metals, its much greater over-all abundance and its ability to combine with oxygen more easily than the others in the group means that significant amounts still remain in the oxidized portions of the earth.The fact that most of the Group VIII metals are available to use in workable concentrations at all is that they are 5 to 30 times more concentrated in the earth's mantle than the crust, as shown in line 4 of Table I. There has been a constant, if slow, interchange of matter between the mantle and the overlying crust throughout most of the earth's history and, under certain circumstances, this interchange has given rise to economic concentrations of metals."

Jan 1, 1979

By A. T. Iannacchione, D. G. Puglio

This Bureau of Mines study covers 25 underground mines that were active in the Upper and Lower Freeport and Lower Kittanning coalbeds in 1976. The coal ranges from low to medium volatile in rank; its primary use is for steam generation. Seven mines emit more than 100,000 cfd of methane gas; those mines are the deepest and largest producers. The methane gas content of three core samples of the Lower Kittanning coalbed was estimated by the direct method. A sample from a depth of 320 feet contained 0.5 cu cm of gas per gram, at 620 feet there was 0.8 cu cm of gas per gram, and at 1,060 feet there was 11 cu cm of gas per gram. These results suggest that methane control problems will be encountered in the future as deeper coal is mined.

Jan 1, 1979

By Harold L. Rhodes

The Bureau of Mines has developed a method for determining the H2S content in natural gas samples. A gas chromatograph with a flame photometric detector was used to analyze samples with H2S concentrations ranging from 5,000 ppm to a minimum detectable limit of 0.01 ppm. A mass spectrometer was used to analyze samples containing H2S in amounts greater than 5,000 ppm. Methods are presented for preparing containers for H2S samples and for preparing standards using partial pressure and weighed standard methods, Sample collection techniques are discussed, as are analytical results which illustrate the loss of H2S while in the sample container and provide a basis for evaluating containers used for sampling and standard preparation.

Jan 1, 1979

By R. G. Hamm

A brief outline covering the shovels and draglines in use in the open-pit mines of Western Canada, including British Columbia, Alberta and the Yukon, is given, followed by the procedure for the selection of the correct wire rope for each application. Such fa ctors as wire rope constructions, lay directions and types of cores are mentioned. Once the correct wire rope has been selected, there are variousfactors that can affect the service fife ofthe rope and the reduction ofdown-time during rope change-overs. Factors such as hairpin winding, types of Becket loops, and shovel drum and bail adaptors are described.

Jan 1, 1979

By A. Koursaris, J. B. See

The influence of Iscor coke and Delmas coal on the reduction of Mamatwan manganese ore to ferromanganese was examined by use of a variation of the 'stationary charge in controlled environment' (SCICE) technique. The charges of Mamatwan ore and the appropriate reducing agent were heated to temperatures between 1300 and I600 °C and either allowed to cool immediately the required temperature had been reached or held at that particular temperature for periods of up to ... hours. The heating rate was 350°C per hour, the particle size of the ore was between 2,83 and 12,7 mm, and the particle size of the reducing agent was between 2,83 and 6,35 mm. After being allowed to cool in air, the reacted charges were examined by optical microscopy, X-ray-diffraction analysis, scanning electron microscopy, and electron-microprobe analysis. No significant difference was found between the changes observed during the reduction of Mamatwan manganese ore by Iscor coke and by Delmas coal. A hypothesis is advanced to explain the mechanism of formation of the Fe-Mn-C alloy.

Jan 1, 1979

By G. L. Dollinger, W. H. Hamilton

INTRODUCTION Design and development of new products generally proceeds through a phase of initial development and discovery based on the evolution of existing arts, followed by technical innovation and development based on both pure and applied research. The development of the mechanical tunnel boring machine (TBM) has followed a similar pattern, with the first machines closely resembling continuous coal miners. In general, however, the design of TBM's to date has been more a result of evolution and discovery than of new technical innovation, even though large sums of money have been spent on research and development. In particular, the results of experimental laboratory and field investigations have had little effect on tunnel boring machine design, and the better performance of TBM's today over those of 10 or 15 years ago, is due more to increased mechanical reliability and greater operating experience, than to improvements in penetration rates and rock fracture capability. The improvements made, have been mainly by the machine and cutter manufacturers who recognize the greater efficiency and economic advantage of utilizing large single row cutters with high load capacity along with large edge spacing. Are there any improvements to be made, therefore, in TBM performance without new and dramatic technological breakthroughs? Can TBM manufacturers design greater performance into their machines by a logical extension of the present art, and by applying what has been learned in the laboratory and field? Some, for example, believe that the kerf cutting system of boring rock is at, or close to, its opti¬mum and little improvement can be made in the present TBM concept.

Jan 1, 1979

By E. J. Mayhew

Bentonite and newly discovered deposits of sepiolite, saponite, and hectorite are now being processed and marketed from the Amargosa Valley of Nevada. All of these deposits are large. The bentonite has been known for decades and is the whitest known. The only other sepiolite deposit is in Spain. The only other commercial hectorite deposit is at Hector, California. No other saponite deposit is known. All the components except bentonite are hydrous magnesium silicates. The bentonite is mixed layer Na-Ca. All the materials have characteristics unique to their locale and type, such as high yield point for drilling muds and liquid suspending agents. The sepiolite has geothermal stability. Figure 1.

Jan 1, 1979

By Peter Bush

The deposition of metastable carbonate minerals in ar. aid, sheltered, coastal environment, leads to the formation of a flat, coastel, sabkha plain. The ground waters of the sabkha plain are modified by evaporation, precipitation of salts and reaction between ions in solution and the host carbonates. The resulting brine is similar to those found in fluid inclusions associated with Mississippi Valley type deposits. The aragonite and high magnesium calcite found in the sediments can concentrate lead and zinc from sea water. On diagenesis the lead and zinc are released into the sabkha brines.

Jan 1, 1979

By John Durkin

A computer model has been generated to evaluate speech intelligibility of individuals wearing conventional and electronic hearing protectors. For speakers talking at normal levels in noise levels of 65 db(Lp) or less, it was found that conventional hearing protectors significantly reduced speech intelligibility. Under the same conditions, electronic protectors provided scores equal to those for the unprotected individuals while providing protection from high noise levels. Therefore, electronic hearing protection is valuable in areas where high noise level is intermittent.

Jan 1, 1979

By Garland R. Dever, Preston McGrain, George W. Ellsworth

Limestone resources for industrial, constructional, and agricultural uses occur on the surface and at minable depths in several areas along the Ohio River and its navigable tributaries in Kentucky. High calcium and high carbonate limestones suitable for use in cement and lime production, steel manufacture, environmental control measures, and other special uses are present in the High Bridge Group (Ordovician) and Warsaw and Ste. Genevieve Limestones (Mississippian). Deposits with thicknesses of 7.3 to 20.7 m,(24 to 68 feet) have been documented by the analysis of samples taken at 0.3-m (1ft) intervals. Active and potential mine and quarry sites afford access to water transporation and proximity to a number of industrial and metropolitan centers. Geologic factors affecting the distribution of deposits include the Cincinnati arch, regional dip into the Appalachian and Eastern Interior basins, complex faulting in and near the western Kentucky fluorspar mining district, and late Paleozoic erosional unconformities in northeastern Kentucky.

Jan 1, 1979

By Fritz F. Prugger

In August, 1970, during routine shaft grouting, a major water source was intersected. Water and quicksand under very high pressure entered the shaft at a rate of 65 m3 per minute. The mine and both shafts were flooded. The breach was sealed simultaneously from within the shaft and through a relief hole drilled from surface. The mine was dewatered, rehabilitated and the equipment was restored. Production resumed two years after the accident.

Jan 1, 1979