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By R. E. Simpson

Beginning in 1972, fully grouted resin bolts were used in underground mines. An estimated 20 million resin bolts will be installed in 1980 owing to their apparent support improvement in most roof-bolt applications. Inorganic cements were tested to replace the resin at a lower cost while retaining the advantages of a grouted bolt. Although other inorganic materials were considered, all but portland and gypsum cements were rejected for reasons of availability, performance, or cost. Portland and gypsum-type cements were tested by the Bureau of Mines to select a fast-hardening, low-cost material that would anchor a roof bolt adequately to meet safety standards. An alpha-gypsum cement, accelerated with potassium sulfate, was selected as the best material because it had adequate pull strength at a desired set time of less than 5 minutes and was readily available.

Jan 1, 1980

By Harold J. Miller

Loading and haulage of run-of-mine ore is frequently the highest cost in underground mining operations. These costs can be significantly reduced by use of belt conveyors, a common practice in coal and similar soft miner ii mines. This is particularly true if oversize ore and rock can he eliminated prior to conveying; thus producing a demand for crushers near the production areas. Portable feeder-breakers are extensively used in conveyorized mines, but no suitable, equivalent equipment, is available to provide these benefits to hard rock mines of low to medium headroom. A hard rock crusher capable of easy movement and readily disassembled would allow use to belt conveyors and could improve the general safety and productivity of any underground ore hauling system. This report summarizes proposals and findings made in conjunction with the newly designed M-44 Low Head Portable Crusher which is believed well capable of meeting the requirements of a "portable, underground, hard rock" machine as previously defined in earlier reports. Data gathered by use of the 1/4 Scale Model of the M-44 has substantiated and verified the concept sufficiently to justify construction of a full-size machine for further testing under actual mine conditions.

Jan 1, 1978

By Stephen Gerard Sawyer

This report presents a Fortran IV computer program for the structural analysis of space-frame protective canopies used in underground mines to protect equipment operators from falls of roof, face, or rib. This program entitled CANOPY permits rapid calculation of the elastic strength of a canopy for a variety of static loading conditions. Stresses in, and displacements of each structural member are computed and printed out. Additionally, identification of all members that have commenced yielding, weight of the canopy, total loads on the canopy, and maximum loads that the canopy can sustain elastically are output. Program description, input instructions, program listing, and two example problems are included.

Jan 1, 1972

By B. C. Peterson

Calumet Division, Calumet & Hecla, Inc., whose operations are in Houghton and Keweenaw Counties, Mich., is a highly integrated and complex organization. This division operates mines, a railroad, a concentrating mill, a reverberatory smelter, and the auxiliary generating plants and shops to service these operations. In addition, it operates a sands reclamation plant, leaching plants, a foundry, and a machine shop that serves varied industries with castings and parts for many applications. Calumet & Hecla, Inc. has produced over 60 percent of all the copper that has been produced in Michigan since discovery of the ore in 1864, and in 1959 the company ranked eight among the country's producers with a production of 17,407 tons. To keep abreast of modern accounting systems developed elsewhere in industry and to combat increasing costs due to higher labor and supply costs, as well as increased costs due to deeper mines and lower grade ore, the company has developed a modern machine cost accounting system. This not only provides the usual bookkeeping and cost accounting facilities but offers accurate cost data for engineering evaluation of the mining operation. This system is credited with being instrumental in permitting continued operation of these high-cost mines in a period of increasing costs with no corresponding increase in the price of metal.

Jan 1, 1962

By F. W. Lee

This paper purposes to outline briefly results of seismic measurements made in the vicinity of blasts in a mine and in open-quarry operations. It endeavors to examine the amplitude and frequency of such vibrations as influenced by the loading, geology, and distance from the source and includes comments on factors that may index the destructiveness of a vibration and a method for measuring the stresses produced. There seems to be no simple mathematical analysis of the transmission of seismic energy through the ground, and experimental observations are at present most feasible. SEISMOLOGIC INSTRUMENTS Instruments developed by the Bureau of Mines for recording ground vibrations from quarry blasting comprise a new type of seismometer, oscillators, and a recording oscillograph. The seismometers respond to vibrations reaching them through the earth and transmit their characteristics by electric current to the oscillograph, where they are recorded by a beam of light on a moving strip of sensitized photographic paper. The seismometers are so constructed that their sensitivity to earth vibration can be controlled, thus keeping the amplitude of the recorded wave within bounds on the paper. Each instrument has been calibrated against vibrations of known intensity and frequency so that correction factors are known for the idiosyncracies of each unit. Moreover, each seismometer is calibrated in the field for its particular sensitivity setting at each blast. By these controls the actual movement of the earth due to vibrations of one ten-thousandth of an inch can be accurately measured.

Jan 1, 1936

By John J. Sammarco

The U.S. Bureau of Mines seeks to increase safety and efficiency in U.S. coal mines. One approach is to develop technology for automation of a continuous mining machine. Realization of an autonomous mining machine requires development of subsystems for machine intelligence, navigation-positioning, and computer control. This report focuses on investigation of one subsystem, an onboard heading system, which would be responsible for determining and controlling machine heading. The onboard heading system investigated is a multisensor system to determine machine heading, pitch, and roll. A directional gyroscope provides heading (yaw), fluxgate sensors provide a compass heading, and gravity-referenced clinometers give machine pitch and roll. The system utilizes a dedicated microcontroller networked to an external system of computers. Tram commands, supplied to the network from external computers, are executed by the onboard system. Sensor feedback is employed for closed-loop control of machine heading by controlling pivots and turns. The report discusses operating limitations and error sources of system sensors and presents test results of closed-loop control of machine heading. Results of tests with a mining machine are used to exhibit various sensor shortcomings and to evaluate control of pivots and turns.

Jan 1, 1990

By Roy T. Sorensen

As part of its mission to maintain an adequate supply of minerals to meet national needs and maximize mineral production from domestic sources, the Bureau of Mines is investigating the recovery of alumina by hydrochloric acid leaching of kaolinitic clay. Most iron impurities are leached from the clay along with the alumina and must be removed before or during crystallization to aluminum chloride hexahydrate. The thermal decomposition step then provides an alumina product of acceptable iron analysis. Miniplant studies of a Bureau-developed solvent extraction technique, using a tertiary amine in kerosene diluent, have demonstrated that the iron content in aluminum chloride leach liquors can be reduced to levels of less than 0.007 wt-pct (7 ppm), expressed as Fe203. Entrained and dissolved organic matter in the purified pregnant leach liquor from the solvent extraction circuit can be reduced to less than 2 ppm by using a fabric-packed coalescer and subsequent activated carbon treatment. Investigators discovered that a steady buildup of zinc accumulated in the solvent phase within the extraction circuit, proportional to the amount of leach liquor treated. The solvent phase zinc analysis increased by 0.01 wt-pct ZnO for each 1,000 gal of pregnant leach liquor purified.

Jan 1, 1981

By William H. Pomroy

The Bureau of Mines, through a 4-year program of combined in-house and contract research, has developed the necessary hardware and software technology to provide rugged, reliable automatic fire protection for surface mining mobile equipment. One element of this program was a continuing effort to help foster rapid mining industry acceptance of the technology by keeping end user costs reasonable. This report is an analysis of the economic impact of surface mining mobile equipment fires and the cost benefit of utilizing automatic fire protection systems to abate these losses.

Jan 1, 1982

By H. B. Carroll

The performance of commercially available portable instrumentation for detecting nitrogen dioxide, sulfur dioxide, and hydrogen sulfide was evaluated. Length-of-stain detector tubes from several manufacturers were included in the study. The instruments were evaluated in atmospheres with 50-and 80-percent relative humidities at 75° F and containing test gas concentrations of 0.1, 0.25, 0.50, 1.0, 1.5, and 2.0 times the threshold limit values. The results from the gas analyzers were correlated with the known contaminant concentration by calculating and plotting an estimated line of regression, confidence limits, and correlation coefficient for each detector system. An increase in the relative humidity from 50 to 80 percent at /5° F changed the instrument response to the contaminants. The uncertainties in detection precision reported are for the observer-instrument system. The main difference or inconsistency in toxic gas concentrations determined with length-of-stain tubes resulted from the observer's interpretation of the results rather than from a predominant difference in the tubes.

Jan 1, 1975

By A. E. Harak

To determine the retorting characteristics of a column of mine-run, ungraded oil shale ranging in size from fines to 5-ton pieces, a 150-ton batch-type retort was designed and constructed at the Bureau of Mines Laramie Energy Research Center, Laramie, Wyo. The retort vessel is 45 feet high by 11 ½ feet inside diameter, and is supported in a 95-foot-high steel superstructure. Mine-run shale from the Bureau of Mines facility near Rifle, Colo., assaying about 25 gallons of oil per ton, was used as the test shale. To date, 11 runs have been completed, and the results of the last 10 of these are reported. The effects of oxygen content of the retorting gas and the superficial gas velocity of the retorting gas on oil recovery from a column of mine-run oil shale were studied. In one run, the average particle size of the shale was substantially increased to determine its effect on oil yield. Oil recoveries ranged from a low of 39.3 to a high of 65.8 volume-percent of Fischer assay.

Jan 1, 1974

By M. C. Bleiweiss

Various light sources were evaluated for use in a fiber optic lighting system for mining machines. It was determined that a metal halide arc lamp was best because of its resistance to damage from shock and vibration and the high luminance of the arc. Measurements were made of the percent transmission of the ½ inch thick glass window and the fiber bundles, the total lumen output of the diffuser assembly with a known input and of the average surface luminance of the diffuser assembly. These data were then used to calculate the theoretical output of the system given an estimated input from the source. A prototype 55 watt, single-ended metal halide source was then developed. In order to provide greater efficacy and higher throughput through the fiber optic cables, a variation of the lamp with thallium iodide added to the fill was developed. The lamp was modified and a ballast was developed to allow it to hot restrike.

Jan 1, 1986

By B. W. Haynes

This Bureau of Mines report describes the laboratory processing of manganese nodules and the results of tailings characterization obtained during the cooperative program with the Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and the Bureau. Five technically feasible first-generation nodule processing methods were operated at bench scale to generate sufficient tailings and slags for physical and chemical analyses. A description is given for the laboratory operation of the individual unit operations of each process. The laboratory-generated tailings and slags were tested for physical properties, mineral content, elemental and ion content, and leachability for all five processes. The results of leachate testing using the Environmental Protection Agency extraction procedure (EP) toxicity test, the American Society for Testing and Materials shake extraction test, and the EPA-U.S. Army Corps of Engineers seawater elutriant test showed very low to negligible leaching of metals from the tailings and slags. Results of the EP toxicity test demonstrated that the wastes are nonhazardous as defined in the Resource Conservation and Recovery Act (Public Law 94-580).

Jan 1, 1985

By F. W. Lee

This paper purposes to outline briefly results of seismic measurements made in the vicinity of blasts in a mine and in open-quarry operations. It endeavors to examine the amplitude and frequency of such vibrations as influenced by the loading, geology, and distance from the source and includes comments on factors that may index the destructiveness of a vibration and a method for measuring the stresses produced. There seems to be no simple mathematical analysis of the transmission of seismic energy through the ground, and experimental observations are at present most feasible. SEISMOLOGIC INSTRUMENTS Instruments developed by the Bureau of Mines for recording ground vibrations from quarry blasting comprise a new type of seismometer, oscillators, and a recording oscillograph. The seismometers respond to vibrations reaching them through the earth and transmit their characteristics by electric current to the oscilloglaph, where they are recorded by a beam of light on a moving strip of sensitized photographic paper. The seismometers are so constructed that their sensitivity to earth vibration can be controlled, thus keeping the amplitude of the recorded wave within bounds on the paper. Each instrument has been calibrated against vibrations of known intensity and frequency so that correction factors are known for the idiosyncracies of each unit. Moreover, each seismometer is calibrated in the field for its particular sensitivity setting at each blast. By these controls the actual movement of the earth due to vibrations of one ten-thousandth of an inch can be accurately measured.

Jan 1, 1936

By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations wi.thin a multiple-seam configuration. At two mine sites where such ground interactions were present, the Bureau performed a complete geological analysis and installed and monitored instrumentation to gather pertinent data on rock mechanics. Overburden depth varied dramatically in the vicinity of the study area and reached a maximum at the study site; innerburden thick-ness was less than a pillar width (40 to 4S ft); heaving was experienced in both mines where sandstone and/or shale floor units were observed; overlays of the mine layouts show pillars were not totally superpositioned; a maximum of S in of roof to floor convergence was measured; and pressure readings indicated pillar core loading only and increased to a maximum of 7,000 psig over instrument setting pressure.

Jan 1, 1987

By E. D. Palmes

Phase I of these studies demonstrated the feasibility of measuring the efficiency and capacity of sorbents in tube-type samplers for contaminant gases. This was accomplished by measuring concentration at various points along the length of the diffusion path during sampling. Concentrations were measured by removing small aliquots with gas-tight syringes and gas chromatography. With hexane as the gas and activated charcoal as the sorbent the procedure was quite successful and we proceeded with Phase II of the study; this involved application of the principle to gases of importance in diesel exhaust using a variety of sorbents. When we worked with high concentrations of the test gas we clearly demonstrated the differences in both efficiency and capacity of the sorbents for each of several gases. The chief drawbacks of the system were that we were unsuccessful in determining more toxic gases at realistic occupational exposure levels or determining formaldehyde at any level using the flame ionization detector. It was concluded that, although the method is feasible, more sensitive methods of measuring concentrations of gas in the tube must be developed to make the procedure applicable to regions of chief industrial hygiene interest.

Jan 1, 1983

By Theodore L. Turner

This Bureau of Mines report describes calcination of kaolinitic clay in a direct-fired 2-1/2- by 24-ft rotary kiln at 750° and 775° C. Methods for preparing kaolin feed materials and characterization of calcined products are discussed. Approximately 99 pct of the alumina in a typical eastern Georgia kaolin was soluble in HC1 after calcination at either 750° or 775° C.

Jan 1, 1982

By G. Chi, A. Solomon, J. Lai

"The Buffalo gold deposit is a small deposit consisting of auriferous quartz-tourmaline veins within a granodiorite stock in the Red Lake greenstone belt. This study aims to characterize the mineralizing fluids through fluid inclusion and stable isotope analyses and to compare them with those of the world-class Campbell- Red Lake deposit. Four types of fluid inclusions were recognized, including carbonic, aqueous-carbonic, aqueous, and halite-bearing aqueous, with the carbonic type being the most abundant. Raman analyses indicate that the carbonic phase mainly consists of CO2, with minor amounts of N2 and CH4, and rarely detectable H2S. The homogenization temperatures of the carbonic inclusions range from -41.7° to 30.9°C. The homogenization temperatures and salinities of the aqueous, halite-bearing aqueous, and aqueous-carbonic inclusions are 130° to 276°C and 9.7 to 23.6 wt.% NaCl equiv., 155° to 207°C and 32.9 to 42.3 wt.% NaCl equiv., and 215° to 357°C and 8.3 to 19.7 wt.% NaCl equiv., respectively. The d18OVSMOW values of tourmaline range from 8.2‰ to 9.0‰, and those of quartz from 11.4‰ to 11.9‰, with estimated fluid temperatures from 323° to 399°C based on the quartz-tourmaline isotopic geothermometer. It is postulated that separate CO2-dominated and aqueous fluids intermittently invaded the fracture/vein system in response to fluid pressure fluctuations, with limited mixing. The CO2-dominated fluid, previously recognized in Campbell-Red Lake as the main mineralizing fluid, is inferred to have been derived from deeper parts of the crust. This deep CO2-dominated fluid reservoir might have been a common source for gold mineralization in the Red Lake greenstone belt. Le gîte aurifère Buffalo est un petit dépôt composée de veines de quartz-tourmaline à l’intérieur d’un stock de granodiorite dans la ceinture de roches vertes de Red Lake. Cette étude vise à caractériser les fluides impliqués dans la minéralisation par les inclusions fluides et par les isotopes stables ainsi que de les comparer avec ceux du gîte de classe mondiale de Campbell-Red Lake. Quatre types d’inclusions ont été notes, incluant des inclusions carboniques, aqueuses-carboniques, aqueuses et aqueuses avec halite, les inclusions carboniques étant la variété la plus abondante. Les analyses par spectroscopie Raman indiquent que la phase carbonique consiste principalement en CO2, avec des quantités mineures de N2 et de CH4, et rarement avec des quantités mesurables de H2S. Les températures d’homogénéisation des inclusions carboniques vont de -41.7° to 30.9°C. Les températures d’homogénéisation et les salinités des inclusions aqueuses, aqueuses avec halite et aqueuses-carboniques sont varient de 130° à 276°C et de 9.7 à 23.6 poids.% NaCl équiv., 155° à 207°C et 32.9 à 42.3 poids.% NaCl équiv., et de 215° à 357°C et 8.3 à 19.7 poids.% NaCl équiv., respectivement. Les valeurs de d18OVSMOW pour la tourmaline vont de 8.2 à 9.0‰, et celles du quartz de 11.4 à 11.9‰, avec une température estimée du fluide entre 323° et 399°C sur la base du géothermomètre isotopique quartz-tourmaline. Il est postulé qu’un fluide riche en CO2 et un fluide aqueux distinct ont envahi le système de fractures/veines par intermittence en réponse à des variations dans la pression des fluides, et qu’il y a eu peu de mélange. Le fluide riche en CO2 est également observé à Campbell-Red Lake ou il est le fluide minéralisant principal, il est présumé être dérivé de portions plus profondes de la croûte. Ce réservoir profond de fluides riches en CO2 pourrait être la source commune des minéralisations aurifères de la ceinture de roches vertes de Red Lake."

Jan 1, 2009

By T. T. Campbell

This investigation was undertaken by the Bureau of Mines to determine if high-purity ductile molybdenum of uniform quality can be prepared by bomb reduction techniques. Molybdenum trioxide (Mo03) and mixtures of molybdenum dioxide (Mo02) and trioxide were reduced by magnesium in closed steel bomb reactors. Very high pressures in excess of 5,000 p.s.i. developed during magnesium reductions of Mo03. The addition of calcium oxide to the bomb charges caused a significant reduction in pressure. Reaction efficiencies higher than 95 percent were obtained during magnesium reductions of either Mo03 or mixtures of Mo02 and Mo03, but high pressures were encountered when the charges contained from 30 to 60 percent Mo02. Reaction efficiencies were usually low (less than 80 percent) when the bomb charges contained more than 40 percent Mo02. The charges with the best composition considering operating pressure, yield, and purity contained from 10 to 30 percent Mo02. The addition of small amounts of carbon to the reaction charges was helpful because some deoxidation occurred during the reduction and also during subsequent arc-melting of the regulus metal. The purity of the bomb-reduced, arc-cast molybdenum metal ranged from 99.2 to 99.8 percent and in some instances the metal contained as little as 5 parts per million oxygen.

Jan 1, 1962

By William A. Stickney

The zirconium-hafnium separation plant at Albany, Oreg., was the result of a chain of events that started with studies by A. R. Kaufmann at the Massachusetts Institute of Technology. Variations in the listed neutron-absorption cross-section of zirconium caused him to suspect a misprint. As a result of these discrepancies and following his suggestions, Oak Ridge scientists made studies establishing a value of 0.4 barn or lower. This meant that the potential of zirconium for reactor application was greatly enhanced. Since hafnium is invariably associated with zirconium and has a high neutron cross-section, it was necessary that an efficient hafnium-separation method be developed before the superiority of zirconium as a structural material in nuclear reactors could be realized. The Albany plant was built and operated for the Atomic Energy Commission (AEC) under Letter Agreement AT-(11-1) -140, patterned after a plant operated by the Carbide and Carbon Chemicals Corp. at Oak Ridge, Tenn. Construction was begun in April 1951. Hafnium was to be extracted preferentially as hafnium thiocyanate from an aqueous mixture of zirconyl and hafnyl chlorides in hexone (methyl isobutyl ketone) by a liquid-liquid countercurrent system.

Jan 1, 1959

By W. M. Deaton

[The formation of gas hydrates in natural-gas pipe lines depends on temperature and pressure conditions in the lines as well as on the presence of condensed water. The operating pressure in a pipe line may be determined easily and usually is available from the records of operation, but the temperature seldom is known. In cooperation with the American Gas Association, the Bureau of Mines, in its investigation of gas hydrates, conducted a pipe-line-temperature survey and studied underground temperatures at depths at which pipe lines ordinarily are buried and the relationship of these temperatures to prevailing atmospheric conditions. A similar but more limited study of this type was, conducted by engineers of the Bureau of Mines a number of years ago.4/A summary of the earlier findings was included in a general report by the Bureau on the flow of natural gas through high-pressure transmission lines.5/ In the present study, data on temperature variations were obtained at several places widely separated geographically. This information should assist pipe-line engineers in designing and operating natural-gas pipe lines. In the pipe-line-temperature survey here resorted, a study was made along a 22-inch natural-gas pipe line: originating near Amarillo, Tex., and extending northwestward through New Mexico into Colorado (fig. 1). Some data also were collected along a 16-inch line extending southward from Amarillo. In the study of underground temperatures and their variation with atmospheric temperature, recording; equipment was installed at the]

Jan 1, 1941