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By Richard A. Allwes

The Bureau of Mines conducted an in-mine case study on two consecutive three-entry gate road systems designed in accordance with the stiff-yield pillar design concept. This Bureau study was conducted in order to further develop technology that will improve the health and safety aspects of longwall mining. Support loading and strata activity were monitored to determine the effects of retreat longwall mining on the gate road ground control system. Analyses of pillar stress and roof bolt loading histories revealed that headgate roof support elements ex-perienced cumulative loading throughout the life of the longwall panel. Tailgate pillar loadings had significantly different histories from the loading histories of the headgate pillars. Stress relief occurred in the tailgate pillars following the passage of the longwall face. More-over, the stiff-yield pillar design, with the abutment pillar placed adjacent to the working panel when part of the headgate system, provided effective ground control in that no major roof falls or roof problems were experienced in the headgate or tailgate systems during longwall mining.

Jan 1, 1985

By Xavier B. Starnes

The Dike and Eaton veins in Crittenden County, Ky. (fig. 1), are along northwesterly trending relief fractures that lie between two northeastward striking major faults - the Moore Hill and- the Levias, in Crittenden County, Ky. The veins contain small, narrow, irregular ore bodies of fluorspar with subordinate quantities of sphalerite and galena. Gravel fluorspar was found on the surface in the Eaton vein, and open-cut mining was in progress on the W. M. Conyer property about 1900. Discovery of fluorspar in the Dike vein came much later, about 1933, on the W. H. LaRue tract, but the principal production on the Dike vein started after the discovery of gravel spar in 1938 on the land of the P. J. Gilless estate. Production from the Eaton vein was estimated at 9,400 tons and that from the Dike vein at 15,700 tons, a total of 25,100 tons. A large part of this production was gravel fluorspar from within 50 foot of the surface. Beneath the gravel spar the veins are very narrow, averaging 2 to 2.5 feet in width, and the ore shoots are small. The deepest mine level was 140 feet below the surface, and the deepest shaft 150 foot. Orb was concentrated by log washer or sent unwashed to custom mills at Marion, Ky. about 6 miles distant.

Jan 1, 1950

By Davis E. Traut

TiC14, AIC13, and VC14 were coreduced simultaneously via a Kroll-type magnesium reduction to form an alloy sponge as part of a research effort by the Bureau of Mines to produce titanium alloy powder. Reduction tem-peratures of 750°, 850°, and 950° C, a range of chloride feed rates from 34 to 152 Ib/(ft2·h), and crucible diameters of 7-3/4 and 10-1/4 in were tested. Microprobe analyses using a 40-um-diam spot showed no effect on alloy microhomogeneity (distribution of Al and V in the Ti, considered critical as a powder property), due to changes in process variables within these ranges. Statistical analysis of these data for alloy sponge indicated greater variation in the chemical composition (AI and V) than that found in commercial Ti-6Al-4V plate or Plasma Rotating Electrode Process (PREP) powder. Therefore, a one-step approach to pow-der, such as grinding the Ti alloy sponge, would not produce a powder product of acceptable chemical homogeneity. An approach that homoge-nized the sponge, such as with a melting step, would produce an accept-able powder product with respect to chemical homogeneity.

Jan 1, 1987

By William J. Wuest

This U.S. Bureau of Mines report presents an overview of ground control considerations associated with floor heave. Factors affecting heave, such as in situ stress, floor characteristics, and mine geometry, are described. Floor-displacement monitoring and data analysis methods are outlined. Finally, floor heave remediation is discussed. The remedial techniques are divided into four categories: mine maintenance, supplemental support, mine structure, and techniques for multiple-seam operations. Other subjects covered in the report include laboratory and in-place testing of floor rocks, U.S. and international case studies, effects of mine layout, determination of excess horizontal pressure, and types of heave failure. The emphasis of this report is on practical considerations; theoretical discussions are kept to a minimum.

Jan 1, 1992

By Friedel. Michael J.

The U.S. Bureau of Mines investigated acoustic emission (AE) and the Kaiser effect in six types of rock: St. Cloud gray granodiorite, Barre granite, Dresser basalt, Salem limestone, Berea sandstone, and a volcanic tuff. AE signatures were used for interpreting the rock deformation stage and for indicating mechanisms of failure in uniaxial compression. The research demonstrated the advantages of using the volumetric stress-strain curve, as opposed to the more conventional uniaxial curve, for correlating AE response signatures with deformation stages and fracture processes in the rock. Standardized experimental procedures were used for the AE monitoring. The Kaiser effect was shown to be capable of determining prestress levels to within a few percentage points in uniaxial compression tests. Also, prestress memory was shown to be retained in the rock for periods of up to at least. 5 months, the maximum period of testing. The Kaiser effect AE technology holds promise for providing a comparatively inexpensive and less complex method for examihing stress history in rock. However, since the conftning stress has a pronounced influence on the Kaiser effect, it must be considered in developing technology for determining peak fteld stresses based on the Kaiser effect.

Jan 1, 1990

By Mackenzie Burnett

Quick-Fix Blowout Stoppings were evaluated in several underground mines as an alternative to conventional ventilation control bulkheads. Blowout stoppings offer considerable savings in bulkhead construction and repair costs if the 0.1 inch H20 of differential pressure required to inflate them is available. The Quick-Fix Blowout Stoppings were utilized successfully in uranium mines in the Southwestern United States where savings in bulkhead construction and repairs to blast damaged bulkheads are estimated to equal $9,500 over the projected 2 year average life of a blowout stopping. Two types of material were evaluated. Five methods of anchoring the stoppings to drift walls were evaluated. Three methods of anchor attachment to the stopping material were evaluated. Blast pressure measurements were made in conjunction with the evaluation of the blowout stoppings.

Jan 1, 1978

By Ted A. Lewtas

The effectiveness of induction fans in ventilating dead headings was studied in the laboratory and underground. The following fan attachments were evaluated: a. Aerodynamic nozzle b. Various lengths of vent tube c. Honeycomb airflow straightener. Various fan locations were also tested. The following conclusions were reached: a. A nozzle on a fan located against the drift wall gives the greatest jet penetration distance. b. Air straighteners are ineffective in increasing jet penetration. c. Induction fans are ineffective in removing contaminants from dead headings without sufficient main ventilation flow.

Jan 1, 1980

By G. H. Keith

The Bureau of Mines determined the mechanism(s) involved in observed anomalous changes in mechanical properties of vanadium-base alloys. Tensile properties of electrorefined and commercial-purity vanadium-base alloys containing up to 5 atomic percent molybdenum or titanium were measured between 77° and 673° K. Snoek oxygen and nitrogen peak heights were measured to determine the changes in dissolved interstitial content caused by increasing quantities of solute. In addition, changes in lattice parameter were followed wit: precision X-ray techniques. Softening, observed in alloys containing titanium, is explained by the formation of a second-phase titanium compound with oxygen or nitrogen. However, because of partitioning of titanium between compound formation and solid solution formation, about five times the stoichiometric amount was required for complete reaction. Addition of 1 percent titanium drastically lowered the strengthening due to strain aging, at 673° K, and 2 percent titanium essentially eliminated it. All alloys were ductile at 77° K. Variations in the tensile properties of the molybdenum-containing alloys are explained by variations in the amounts of interstitial impurities present. The molybdenum did not react with these impurities and had no effect on strengthening due to strain aging. Commercial-purity vanadium alloys containing more than 2 percent molybdenum were brittle at 77° K.

Jan 1, 1969

Southeast Alaska's mining industry has come to life after nearly 50 years of relative dormancy. Commencement of operations of the Greens Creek Mine in 1989 marked a turning point in the industry as the first large scale mining operation in the region since closure of the Alaska-Juneau Mine in 1944. The Greens Creek Mine is now the nation's largest silver producer. Other large scale mining projects are now on the drawing board, including development of the Kensington Mine and reopening the Alaska-Juneau Mine, which could become North America's largest underground gold mine. The region's mining industry includes more than these large scale projects, however. For example, a significant level of mineral exploration occurs each summer in Southeast Alaska. In addition, mining operations in British Columbia and Yukon Territory are generating jobs and income in Southeast Alaska.

Jan 1, 1992

By G. K. Derby

The Bureau of Mines investigated methods for removing dragline bucket wire rope terminations with the objective of finding efficient methods that are safer than the method most commonly used at U.S. surface mines, which is to use the explosive impact of a projectile fired from a cannon to remove the rope termination. Removal of a wire rope termination for repair or replacement requires separation of the wedge and socket that lock together to secure the rope end. The Bureau investigated currently used methods and improved upon and tested two safer alternate methods for removing wire rope terminations. A cannon test program was conducted, using 40-and 50-gr primer (detonating) cord, to establish the possible force produced with a 4-in-bore cannon and a 55-lb projectile. Wedge and socket units supplied from cooperating mines were separated under controlled conditions to establish data on separation force requirements. The two alternate methods investigated were use of the force generated by (1) a pendulum ram and by (2) a portable hydraulic pusher. Both methods are capable of providing sufficient force to effect wedge and socket separations on draglines with up to 78-yd3 buckets under normal conditions.

Jan 1, 1984

By Thomas J. Albin

This U.S. Bureau of Mines report identifies potential causes of slip-and-fall accidents occurring during surface mine equipment maintenance and describes the relative roles of direct worker behavior and machine design. The relative roles of human behavior and machine design in the causation of slip-and-fall accidents were determined through analysis of accident records, observations of maintenance worker behavior, and evaluation of mine machinery. From these data, relative risk ratios were calculated. Behavior had a relative risk ratio of 1.5; machine design, specifically access systems design, had a relative risk ratio of 2.2. Of the access systems, ladders had the highest relative risk ratio, 7.0. This study suggests that accident intervention would be most profitably made in improving the design of systems used to access maintenance worker areas of mining equipment.

Jan 1, 1990

By James R. Boyle

The mining methods and practices used at the Young zinc mine, American Zinc Co. of Tennessee, have resulted in a low-cost, high-yield operation. Zinc ore (sphalerite) occurs in limestone-dolomite beds of the Kingsport Formation and is mined by modified room and pillar method. Utilizing trackless mining equipment which incorporates a high degree of flexibility, this operation has had a steady increase in productivity.

Jan 1, 1965

By Stephen M. Jasinski

The development and industry adaptation of advanced technologies have led to many important uses for bismuth and its compounds. Bismuth-base alloys are essential for manufacturing jet engine turbine blades, lenses, and various safety devices, such as fire-protection sprinklers. The addition of bismuth to iron, steel, and aluminum imparts properties to these metals that makes them useful in diversified applications. Bismuth is also used widely in medicine, pigments, and electronics. The United States relies heavily upon imports from South America and Europe to meet its demand for bismuth, which is recovered chiefly as a byproduct of lead processing.

Jan 1, 1992

By George H. Schnakenberg

Automation of coal mining activities at the face offers improvements in worker safety, health, and productivity. Introduction of integrated computer-sensor systems to current mining machines will enable these machines to perform some of the most hazardous tasks through supervised teleoperation. The U.S. Bureau of Mines is pursuing the development of the enabling technology necessary to achieve this goal. The research program consists of both basic and applied research, each focused on the fundamental issues of computer and sensor technologies. Short-term research is directed to providing computer-assisted, remote supervisory operation of present underground equipment; the long-term goal is the development of progressively more intelligent mining systems. The research program includes a review of robotic machine and autonomous vehicle technologies and of current mining technology, which provides a base for developing innovative mining methods; research in navigation and guidance technology, emphasizing control of a continuous mining machine; research on coal-rock interface sensing technology for horizon control, and rib thickness control in highwall mining; the development of computer systems and hierarchical architectures for real-time control; and development of expert systems for machine system fault diagnostics and predictive maintenance. This report presents a brief background and the current status for each of these research areas.

Jan 1, 1989

By R. R. May

A preliminary examination of the Houston strip-coal mine, situated on the Alaska Railroad at milepost 175 (61 rail miles north of Anchorage, Alaska) and a review of all available information resulting from early coal exploration activities in the area resulted in plans to investigate the coal-bearing formations at depth by means of diamond core drilling to indicate the existence of additional reserves of coal in close proximity to railroad transportation, where it would be quickly available to meet rapidly expanding military and civilian fuel requirements. From the date of mobilization of equipment, August 28, 1951, until date of suspension, August 18, 1952, 2,010 feet of diamond drilling was completed. Ten definable coal beds were cut, of which 2 appear to be persistent and minable over an area of approximately 1/2 square mile. Within this area the 2 minable beds contain approximately 5,000,000 tons of coal in place. Of the remaining beds, at least two others may be minable to the eastward near their projected outcrops; however, these and deeper beds (at least in the vicinity of the drill holes) lie beneath a zone of pressurized gas and brackish water. From a practical standpoint, continued development and utilization of the coal in this vicinity will depend on the operators' ingenuity in developing cheap mining methods and on diligent prospecting for strippable coal under the comparatively light glacial cover.

Jan 1, 1957

By John E. Pahlman

The Bureau of Mines conducted column-leaching tests on 25 domestic Mn ores to determine the feasibility of extracting Mn by in situ or heap leaching with dissolved sulfur dioxide (S02) solutions. The ores tested were obtained from deposits in Arizona, Arkansas, California, Colorado. Maine, Minnesota, Nevada, and South Dakota. Dissolved S02 was found to be effective for leaching Mn; extractions greater than 90 pct were obtained with solution application rates of 1 mL/min from uncalcined, minus 2.5-plus 1.3-cm ore pieces. Leaching these ores with solutions containing only 5-wt-pct S02 and no added H2S04 resulted in Mn being selectively extracted over Fe except when Fe was present as goethite or siderite. Ca solubilization was inhibited by controlling the solution application rate (1 mL/min). The rate of leaching was found to be principally dependent upon the rate at which the leaching solution can penetrate the ore, since the solubilization of Mn upon contact with S02 was observed to be rapid. Despite low water permeabilities of the ores (as low as 10-2 to 10-4 darcy). greater than 90 pct of the Mn was extracted from even the largest ore pieces tested (approximately 10 cm in diameter). It appears, therefore. that leaching Mn opens up the pores, allowing penetration of the leach solution into the ore pieces.

Jan 1, 1988

By H. Kenworthy

"INTRODUCTION ..Although the occurrence of iron ore in Missouri was recognized by Marquette as early as 1673, the first known mining and smelting operation was conducted in 1815. This operation was near Arcadia, Iron County, the first of its kind west of the Mississippi-Ohio River system. Several small furnaces of short life were erected in Missouri in the ensuing 30 years. However, until the extensive deposits of Iron Mountain and Pilot Knob were opened between 1843 and 1850, the state remained a minor producer of iron. It was this district which was chiefly responsible for the prominent position Missouri held in the iron industry until the late 1880's. At this time the easily minable high-grade ores became exhausted and the discovery of the immense Lake Superior deposits depressed the raw-ore price to such an extent that any mines ceased to operate. 3/Small yearly production of iron ores continued in Missouri to the present. Owing to war demands for hard ore suitable for open-hearth steel, the M. A. Hanna Co., through its subsidiary, the Ozark Ore Co., reopened the Iron Mountain, deposits and installed new equipment in an old concentrator to handle the low-grade ores left from previous operations. At present, ore production is from open pits, but underground mining is contemplated in the future. About 2,000 tons a day of iron ore is treated by gravity concentration of material from the open pits in the immediate vicinity. The concentrate is shipped to the Birmingham, Ala., district and to Granite City, Ill., for smelting. The coarse tailing is sold for ballast and concrete aggregate. The iron requirements of the concentrate stipulated by the purchaser are not difficult to meet, but the phosphorus is frequently higher than desired. For 1946 the concentrates averaged 54.18 percent iron and 0.235 percent phosphorus with low sulfur. The Ozark Ore Co. concentrate, however, sometimes contains as much as 0.40 percent phosphorus. The phosphorus in ores from those portions of the deposits wherein the phosphorus occurs with siliceous gangue is readily rejected in the milling, but in much of the ore the phosphorus is associated with the iron and concentrated with the iron minerals. Selective mining is impossible owing to the spotty occurrence of the phosphorus mineral. Often within 5 feet the ore will change from low phosphorus to high phosphorus, and it would be expedient to find a method of rejecting enough phosphorus at the mill from the latter type of ore to meet the phosphorus specification."

Feb 1, 1948

By Daryl R. Tweeton

The Bureau of Mines compared the effects of surface-active chemicals with those of pure water on core-drilling rock and quartz and on fracturing quartz. The objectives were to determine if these chemicals assist drilling and fracturing rock and if zeta potential control was worth pursuing as an aid to full-scale drilling. All tests were performed in the laboratory. No significant increases in drilling rates were observed for 1 to 10,000 ppm Al (as AlC13) in flushing water when drilling microcline or serpentine, nor for 1 to 10,000 ppm Mg (as MgC12) when drilling microcline or marble. Concentrations near those giving a zero zeta potential were used with microcline and marble. A 50-pct rate increase was observed for drilling quartz in 0.7 ppm oleylammonium acetate, which gave a zero zeta potential. No other concentrations were used. No effect on the tensile strength of quartz thread in 0.05 ppm Al (as AlC13), which gave a zero zeta potential, was observed. Heptanol, reported to give a zero zeta potential on quartz, did not reduce the bending strength of small quartz bars below that in water. These generally negative findings raise doubt about the usefulness of zeta potential control in full-scale drilling. The results, combined with previous studies, suggest that controlling physical properties of drilling fluids, such as viscosity, is more useful than altering chemical properties.

Jan 1, 1976

By Paul Hatmaker

Diatomite is the name now generally given to a mineral substance composed of the tiny , skeletal remains of diatoms , which are microscopic , flowerless , water plants related to the algae ... This residuum is essentially hydrous amorphous silica. Common names for diatomite are : Diatomaceous earth , tripolite , kieselguhr , and infusorial earth . Strictly speaking , however , the latter material is not diatomite , as it is composed of the fossil remains of infusoria , which usually do not occur with the diatomaceae . Other synonyms for diatomite are : Diatomaceous silica , kieselmehl , bergmehl , diatomeenpeelite , polirschiefer , moler , molera , molererde , de smid earth , fossil flour , mountain flour , farine fossil , white peat , radiolarian earth , chalk rock, ceyssatite , randanite , and tellurine ; also various diatomite products of individual companies are known by their own trade names . Diatomite should not be confused with fuller's earth , for the two are separate and distinct substances . Bentonite , pumice , and tripoli , have also been used erroneously to designate diatomite . Tripolite , however , is a true diatomite formerly mined near Tripoli ..

Feb 1, 1931

As a part of its overall wealth in fuel resources, the United States possesses large reserves of coal of ignite rank. According to recent estimates of the Federal Geological Survey (3, 5),l/ the assured lignite reserves of this country amount in total to over 463 billion tons, equivalent to 24 percent of our total national coal reserve on a tonnage basis and 15 percent on a heating-value basis. Distribution and relative amounts of United States coal and lignite reserves are indicated in figure 1. By far the largest proportion of our lignite reserves, over 95 percent is found in North Central States, principally in North Dakota, South Dakota, and Montana, in the vast coal-bearing structural grouping designated as the Fort Union formation. Of the remaining United States reserves, all but a fraction of 1 percent are found in a series of relatively scattered deposits in Texas.

Jan 1, 1954