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By William J. Karwoski

To improve rock-burst control in deep vein mining, a field demonstration has been carried out by the Bureau of Mines to test a new rock-burst control concept--rock preconditioning in advance of mining. The procedure is to fracture the major rock-burst-prone zone during the development of each level before production mining. This allows initial mining to begin in a preconditioned zone and later mining from the level below to end in a prefractured or preconditioned pillar zone that is relatively burst-free. This full-scale field demonstration was carried out On the 7700 level of the Hecla Mining Co.'s Star-Morning mine. An expected burst-prone zone along the main vein between 7 and 10 crosscuts, some 250 feet long by 40 feet above and below the level, was preconditioned by blasting a fanlike ring of drilled holes from each crosscut. The drill holes, up to 100 feet long and 4 inches in diameter, were loaded with high explosives and shot. About 4,550 feet of drilling and 9,000 pounds of explosives were involved in the effort. Comparison of preshot and postshot data from monitoring instrumentation indicated that the blasting did fracture the rock in the planned zone and did result in an immediate stress decrease and softening of rock. The field data compared favorably with predicted results from a finite-element computer model simulation of the destressing. Based on observations made during mining and on the data from the Hecla rock-burst monitoring system, there is no doubt that this preconditioning in advance of mining demonstration resulted in much-improved rock-burst control during first-floor mining. It was also concluded that preconditioning the vein was more effective than preconditioning the wall rock.

Jan 1, 1979

By F. J. Perzak

The Bureau of Mines conducted a flammability study of plastic ventilation ducts. Six rigid 16-in-diam fiberglass-reinforced plastic ducts from five manufacturers were examined using laboratory-scale, large-scale, and full-scale fire tests. The laboratory-scale tests included the American Society for Testing and Materials E162 radiant panel test, the E2863 oxygen index test, and the standardized small-scale flammability test (S3FT) developed by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, and replicated by the Bureau of Mines. Ten-foot lengths of the same ducts were also subjected to a large-scale vertical fire test, and 20-to 30-ft lengths were tested in a full-scale in-mine fire test at the Bureau's Lake Lynn Laboratory mine. The data from the laboratory-scale radiant panel test and oxygen index test indicated that the ducts were fire-resistant, However, five of the six ducts failed the S3FT and vertical fire tests, and four of the ducts failed the full-scale in-mine tests with flame propagation rates that ranged from 3 to 10 ft/min. The results indicate the need for improved fire-resistant plastic ducts. The good agreement between the S3FT re-sults and the vertical and full-scale tests show that the S3FT provides a good indication of the flammability of fiberglass-reinforced plastic ducting under realistic fire conditions.

Jan 1, 1987

By K. L. Bainbridge

This report describes the results of a study to determine which types of, and to what extent, mining wastes can contaminate groundwater through leaching of acid-forming or potentially toxic constituents. The primary focus of this study was on coal mining wastes, especially overburden spoils and preparation plant refuse. In addition, the potential for contamination by leachates from clean coal stockpiles was also examined. The study approach included investigation of (a) the amounts and geographic locations of mining wastes in the United States; (b) the chemical character of mining wastes, especially with regard to potentially acid-firming or toxic constituents; and (c) the extent to which acid and/or toxic components are leached from mining wastes by rainwater. To evaluate the leachability of coal wastes, a laboratory waste leaching method was developed during this study to specifically simulate the leaching process over a long-term. Waste samples collected during this study were also leached by the EPA extraction procedure and ASTM waste leaching method. Results of the three leach test methods were compared to evaluate their relative capabilities to predict the leachability of mining wastes.

Jan 1, 1980

By Sara Jane Boles

In recent years the demand for products of greater refractoriness has placed an ever-increasing emphasis on ceramic materials, including the metallic oxides. Magnesia (MgO) is one of the most important of these oxides, exhibiting, as it does, high electrical resistivity, high slag resistance, and a melting point of 2,800° C. However, magnesia has a tendency to hydrate in the presence of water and to volatilize above 1,500° C. in certain kiln atmospheres and has a comparatively low resistance to thermal shock. Because of these disadvantages, the previously listed advantages inherent in this material have been largely overlooked, and research on magnesia has lagged behind that on oxides such as alumina and zirconia. This bibliography has been prepared in an effort to present to Government and industry a comprehensive picture of the prospects for greater utilization of magnesia as a refractory material in future research. To provide as selective and accurate a collection as possible, the references included cover magnesia in a pure state, not as an additive or in combination with other materials. However, several references discuss the effect of minor impurities (less than 5 percent of the total) on the properties of magnesia, as these papers are considered to be of special importance. A few references to articles on forming techniques are also included, as they are valuable additions to the overall treatment of the subject. The processes used in obtaining and refining the raw materials are adequately covered in earlier publications and are excluded. A number of references are omitted as being of questionable value in enhancing the cumulative study of pure magnesia as an ultra-high-temperature refractory material.

Jan 1, 1962

By Jr. Frank Parrish

This report describes the performance of 17 selected water-injection projects producing from Pennsylvanian-and Permian-age reservoirs. Illustrations depict reservoir structure and thickness, and production and injection history. A selected bibliography of publications pertaining to area oil recovery and geology is included. Tabulations of field and reservoir data reveal marked differences in the projects. Increased oil recovery resulted from injecting water in most cases; however, seven projects recovered less oil than the operators anticipated. Oil recovery by water injection ranged from 0.2 to 262 bbl per acre ft, or 0.1 to 22.5 pct of the initial stock-tank oil in place. Major reasons suggested for poor performance include: (1) Adverse directional horizontal permeability, (2) channeling of injected water through fractures or zones of high permeability, and (3) lack of containment of injected water. One 330-foot-deep project is among the first successful shallow water-floods in north Texas. Another project is the first successful Canyon sand-stone waterflood reported in the area. Previous gas injection in two Cisco sandstone projects did not prevent the reservoirs from responding favorably to waterflooding.

Jan 1, 1965

By George K. Clement

Manual estimating method through use of equations, factors and curves for preparation of feasibility type estimates for capital and operating cost of mining and primary beneficiation in the United States and Canada of various types of minerals occurrences, except fossil fuels, using state-of-the-art technology. User should have basic estimating experience in the mining industry and/or related fields. Primary usage of this handbook will be for the preparation of preliminary estimate within a reasonable degree of accuracy with relative small amounts of hard input data. Output may be used to determine if a more finite type of estimate should be produced.

Jan 1, 1978

By Arcy, D&apos Banister

The productive potential of the Nation's principal active and inactive silver mining districts has been evaluated, using 1964 economic conditions and assumed silver prices ranging up to $3 per ounce. On this basis, the United States has an estimated 5 billion ounces of unmined silver, excluding minor byproduct silver in gold deposits. Approximately 3.5 billion ounces are contained in deposits requiring higher silver prices to be economically minable, and about 1.3 billion ounces are in currently operating mines. An analysis of silver consumption trends since 1954 indicates that the free world industrial market will climb to nearly 800 million ounces annually by 1985. U.S. industrial silver consumption has been projected to increase at an annual rate of 4 percent from 1965 to 1985. Average annual increase for the remainder of the free world has been 8.1 percent since 1953; this is expected to level off with an estimated average increase of 5 percent to 1975 and 4 percent from 1976 to 1985. Foreign silver production has, in the past, exceeded consumption, but in 1960 the supply deficit was over 100 million ounces. U.S. production, also traditionally exceeding demand, was suddenly overtaken at the start of World War II. By 1964 the annual deficit, excluding coinage, was over 84 million ounces. World coinage requirements of silver are fast declining and expected to total only 25 million ounces annually by 1985. In fact, coins are already becoming major short-term source of silver to fill the large deficit between industrial demand and current production. The larger, long-term deficit (to 1985, the limit of this study) must be balanced by silver from the hoards and new production from silver deposits. Eventually all of the deficit must be met by new production or silver prices will rise until consumption is greatly curtailed. To balance free world supply and demand, it is estimated that the free world must produce an additional 85 million ounces by 1975 and 375 million ounces by 1985. The estimated proportion expected from U.S. deposits is 17 million ounces by 1975 and 74 million ounces by 1985.

Jan 1, 1969

By M. Jaffe

The data developed in this study establishes the technical and economic feasibility as well as the improved health and safety characteristics of a novel mining concept. The mining concept is a modified longwall technique using prestressed tendons for roof control, longhole blasting for fragmentation, and remote mucking. The technical feasibility was found to be dependent on the state of the art, while economic feasibility was found to be dependent on particular minerals and on supply and demand. Since these two conditions are not necessarily coincident in time the data is presented in the report in a manner that enables the mining engineer to perform a rapid preliminary technical and economic analyses for a specific property.

Jan 1, 1977

By W. A. McKinney

The segregation process consists of heating crushed oxidized or mixed oxide-sulfide copper are with a copper-volatilizing salt and carbonaceous material at about 750° C. to produce metallic copper which is recovered from the furnace calcines by conventional sulfide flotation. The Bureau of Mines made a number of bench-scale laboratory tests on two copper ores to determine the relative merits of using halogen salts, potassium chlorate, or various salt mixtures as volatilizing agents in segregation of the copper. Laboratory investigation of typical siliceous and calcareous oxidized ores revealed that sodium chloride was a better segregating agent than the other salts. Calcium chloride, magnesium chloride, sodium fluoride, or potassium chlorate gave nearly as good segregation as the sodium chloride on the siliceous ore. Segregation of the calcareous ore with calcium chloride was nearly as good as that obtained with sodium chloride, but inferior segregation resulted when magnesium chloride, sodium bromide, or potassium chlorate was employed. The use of sodium bromide or sodium iodide on the siliceous ore, and of sodium fluoride or sodium iodide on the calcareous are, gave appreciably poorer segregation than sodium chloride or the other salts. Other tests of the ores, using mixtures of sodium chloride and the other halogen salts or potassium chlorate, gave segregation approaching that obtained with sodium chloride.

Jan 1, 1962

By Robert S. Becker

The results of a laboratory investigation of coal cutting mechanics and noise is presented. These experiments were performed using a linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts is ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to Formulate analytical models of the coal cutting forces and noise. The analytical model For coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as Provide benefits to other important areas of underground health and safety.

Jan 1, 1980

By Ronald W. Stingelin

This study undertook the development and implementation of a methodology for estimating the impact of coal seam interaction on the eastern bituminous underground reserve base as published in USBM Information Circular 8655. The effects of previous mining in multiple coal seam areas on currently mined and reserve seams are predicted as a percentage coal loss by an engineering assessment model called the Coal Loss Calculation Model. The model utilizes twelve input variables easily derivable from mine maps or other existing data sources and calculates the effects of subsidence and high-stress due to remnant pillars in the previously mined seam. Extensive literature review resulted in the identification, definition, and quantification of the critical variables of seam interaction. Export opinion surveys were made of mining experts, MESA mine inspectors, and coal mine operators. Statistical analysis was used to establish the redundancy of the critical variables and to develop a total coal loss prediction algorithm. A regional analysis resulted in the production of a series of thematic maps on coal characteristics and distribution. A derivative map showing the areas of commonality within the eastern bituminous coal region served as the basis for implementation of the coal loss calculation model. The model was developed and tested using data from four coal mines in western Pennsylvania and southern West Virginia.

Jan 1, 1976

By T. A. Klinefelter

KYANITE and the related minerals sillimanite, andalusite, dumortierite, and topaz are natural aluminum silicates that can be used in production of mullite (3A1203?2Si02), a superduty refractory material. Kyanite and sillimanite are the dominant ones because of their greater abundance. The only other kyanite-group mineral presently used for mullite production is andalusite. Mullite is not an absolutely essential material as other refractories can be used in the same heat range. However, it is a highly satisfactory one. It is the only compound of silica and alumina that is stable at high temperatures. It has low thermal expansion and is very resistant to corrosive melts and to thermal shock. For these reasons mullite refractories have a much longer life than standard fire-clay refractories under the same conditions. Worldwide, excluding U.S.S.R., the refractories industry consumes about 150-000 short tons annually of kyanite group minerals and synthetic mullite.

Jan 1, 1961

By K. L. Paciorek

The primary objective of this program was to determine the toxic fume and fire hazard of materials used in the construction of mine stoppings and in the sealing and reinforcing of mine ribs and roofs. The materials investigated were: silicone, phenolic, and isocyanate-based rigid foams, as well as epoxy and acrylate mine sealants. Of the rigid foams tested, the X-156 urethane foam presented the greatest toxic hazard based on toxic load values hydrogen chloride was the main toxic species evolved by this foam. In 'lone of the isocyanate-based compositions was hydrogen cyanide the major component, but its contribution increased with temperature. The FS-24 urethane and Celotex Max-Seal isocyanurate foams had the lowest toxic load values, although these two foams have different applications for in-mine use. Of the two mine sealants tested, the latex /acrylic coating presented the greater toxic hazard with acetic acid being the main toxic species evolved.

Jan 1, 1983

By D. S. Burgess

This report summarizes the incidents that preceded the December 9, 1970, propane-air explosion in Port Hudson, Mo., and then attempts to establish the nature of the explosion from the ensuing events. Special emphasis is given to possible ignition sources, the distribution of flammable vapors, and the analysis of blast damage. Both near-and far-field damage indicated that this explosion may be attributed to the detonation of propane in air with an energy release equivalent to that from about 50 tons of detonating TNT.

Jan 1, 1973

By A. Gene Collins

Potassium, lithium, strontium, barium, and manganese are present in many oilfield brines, None of them except barium is determined routinely in brine analyses. Therefore, sensitive and accurate flame-spectrophotometric methods were developed. Potassium, lithium, and strontium were determined by a standard-addition technique in ethyl alcohol solutions. Barium and manganese were determined in ethyl alcohol and normal propyl solutions, respectively, after interfering substances were removed.

Jan 1, 1962

By Noel N. Moebs

The U.S. Bureau of Mines is conducting research on many topics relating to the mineral resources of the United States. This is done to ensure an adequate supply of minerals essential to a viable domestic industry and a sound economy. The United States is almost totally dependent on foreign supplies for a number of minerals such as chromium, niobium, tantalum, and manganese for which there is no available substitute, while many other minerals such as titanium are abundantly distributed throughout the earth but seldom occur in adequate concentrations or useful forms. This report describes an example of a small but high-grade occurrence of titanium are in Nelson County, VA. This occurrence could be exploited under favorable economic conditions with new mining technology such as borehole slurry mining. The report demonstrates that the dikes at titanium ore, a mixture of ilmenite and apatite locally termed nelsonite, can be detected and traced along strike using magnetometer traverses. This information will aid in the selection of appropriate slurry borehole mining test sites in the area.

Jan 1, 1993

By E. C. Lane

["_&apos;_-is is t`-e tenth in a series of retorts on proferties of cornmerci-al motor fuels, m,-_de in accord^nce ::ith a cooper: tine aSreement between the Cooperative Fuel scorch (C.F.R.) Committo e ^nd the. PPure__u of Mines of the United_ States De_nartr.ent of the Interior. Zee first report rave data. on motor gs.solir_es sold. during .e winter of 19,-"1-3b. e are ent report presents an^..lytico1 data f&apos;i&apos;r samples, rerrerentin_E, t:-.e products of apyroximately 90 conr.anies, hich, as in previous surveys, include both lame and stall surnliers. In ?_"dition, the Pacific coast is represented by data that were avera,;el ty the Pacific Coast Technical Group before bein submitted and are rublisi,ed exectly zis they were received. As in previous s?nrve,rs, the data r~Lre divided into the three groups of samples of regular-price, premiu::--trice, and third-grade gasolires, and each group has been averaged sel c~r~.tely. he number of nmtles, items, and brands comprising each groan), exclusive of those of the Pacific coast, are as folio:;s: Reg<.~-lar price, 934 ca.^rnles, 2c0 i to s, and ~0 brands; premium price, 460 saris les, lPitems, an&apos;. -C` brat&apos; i _~ t__ rd grade gaseline, 360 samples, 177 i te.^..s, and of these terms as _ised in the surveys are a:: follows:]

Jan 1, 1941

By Luis v. Coppa

Since its inception in 1910, the Bureau of Mines has been the principal Federal agency involved in ore reserve estimations, using such traditional methods as polygons of influence and variations of inverse distance weighting While adequate for estimating the average are grades in a mining block or section, these methods do mot, however, provide a consistent way of quantifying the reliability of the estimates. This report describes a technique for enhancing ore reserve estimations using geostatistics, the methodology of which combines the spatial and random aspects of geologic phenomena into a formal theoretical framework for deriving the estimation variance of ore reserves. Correctly used, geostatistics enables confidence intervals to be placed around ore reserve estimates calculated from drill hole data. A geostatistical software system was obtained -From the U.S. Geological Survey and installed, aster slight modifications, on the Bureau&apos;s Wang computer. System testing and validation was conducted using a simple cast-book-type example. This was then followed by variogram analysis, point kriging and block kriging of data from a previously worked section of a uranium mine.

Jan 1, 1984

By C. C. Stevenson, Thomas Varley, E. P. Barrett, ROBERT H. BRADFORD

The art of treating ores by the chloride volatilization process is still in the experimental stage. The process has not been sufficiently developed along metallurgical lines to warrant a definite statement as to the exact place it will occupy in the industry. The basic theory of the process has received the attention of prominent metallurgists for 20 years, and considerable research and experimental work have been carried on. Much of the experimental work done has never been published; if the accumulated results were made known, they would greatly aid,. the further development of the process. This bulletin aim~ to bring the salient features of the process to the attention of metallurgists for the purpose of furnishing information to and receiving comments from interested parties with the ultimate hope that the process will be a commercial success. If commercially utilized, the process will fill a long-felt want in metallurgy, especially in the treatment of oxidized and semioxidized or" carbonate" ores of copper, lead, and silver. Such ores are difficult to treat by gravity concentration or by flotation: in the former their tendency to slime upon crushing and their being of lower specific gravity than the sulphide minerals cause serious losses; in the latter much has been done in sulphidizing oxidized ores and subsequently recovering the artificial sulphides by flotation. Difficulties in proper sulphidizing and the low recoveries obtained have not balanced the cost of the treatment in many plants and in very few has it proved successful. Evidently there is a big void to fill in the treatment of these ores. No radical changes in present methods are forecast, but it is obvious that chloride volatilization can have a distinct place as a method of treatment for ores that are not readily amenable to present methods. In many plants it might replace concentration methods, especially where part of the mineral content in the ores exists in forms other than sulphides.

Jan 1, 1923

By W. R. Reed, J. A. Organiscak

Haul trucks have the potential to generate large amounts of respirable dust. This respirable dust has been shown to be a health hazard to personnel, especially if it has a high silica content. Lack of dust sampling data from haul trucks prompted the completion of a study to quantify respirable dust concentrations. These field studies were conducted measuring instantaneous respirable dust at stationary locations from passing haul trucks at a stone quarry and at a coal mine site. Fugitive dust levels from haul trucks were analyzed to characterize dust dispersion. This analysis indicates safe following distances for haul trucks and other heavy equipment to avoid overexposure of respirable dust from the lead haul truck.