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By P. D. Lohn

The objective of this program was to develop nozzle designs to maximize the effective cutting length of a water jet. The results of the theoretical program directly support the Bureau of Mines Borehole Mining Program and their experimental program to improve the rock cutting capability of water jets. The borehole geometry requires turning the flow by 90 degrees and accelerating through the nozzle within a restricted length. Several suggestions for turning the flow are offered. The borehole space limitations constrain nozzle length, to the extent that a standard 13-degree tapered nozzle (6-1/2 degrees half angle) is too long to fit in the borehole, at production flow conditions. The design technique developed is computationally economical and enables examination of a large number of shapes and flow conditions. The nozzle design is based on design criteria of minimization of boundary layer thickness at the nozzle exit and minimization of the possibility of separation and cavitation. Six flow conditions, including pressures to 4500 psi and flow rates to 400 gpm, were examined, Best shapes were determined for all flow conditions. The best shape for a borehole reining application consists of an initial 4th degree polynominal (quartic) at the entrance followed by a straight section with a twenty degree (half-angle) taper at the exit.

Jan 1, 1976

By Charles E. Whieldon

The importance of producing more oil from known petroleum reserves has placed increased emphasis on the application of secondary-recovery methods. Recently published reports3 4/ describe the results of waterflooding in Roane and Pleasants Counties, W. Va. (see fig. 1.) This report describes the Barron Kidd Oil Co.?s Santee waterflood project, Maxton sand, Burton field, Church district, Wetzel County, W. Va. (See fig. 2.) The Federal Bureau of Mines hopes that these reports will stimulate interest in improved waterflooding techniques, thereby discouraging premature abandonment of oil leases.

Jan 1, 1961

The Bureau of Mines conducted large-scale laboratory copper ore leaching tests to enable improving copper recovery from large dump-leaching operations. This was done by comparing leaching progress when copper was recovered from recycled leach liquor either by cementation or by solvent extraction. Copper was leached from 7-ton ore samples at room temperature using pH 2 ferric sulfate solutions. With are samples containing 11 percent minus 0.5-inch fines, no marked advantage in using either of the copper recovery methods was evident after 416 days of leaching. With ore containing 32 percent minus 0.5-inch fines, solvent extraction of copper was advantageous in that 60 percent of the copper was extracted after 568 days, whereas only 48 percent of the copper was extracted when cementation was used. Less acid was consumed during leaching when solvent extraction, rather than cementation, was used for copper recovery. Iron, contributed by cementation with scrap iron, plugged the ore bed containing 32 percent fines.

Jan 1, 1981

By T. M. Barczak

A primary objective of the Bureau of Mines geomechanics research program is to develop a better understanding of support behavior and interaction of supports with the strata so that supports can be more closely engineered to the geological conditions in which they are employed. Four longwall shield supports were instrumented with an eight-transducer instrumentation array to measure leg, canopy capsule, and compression lemniscate link forces from which resultant shield loading was determined. The instrumented supports were monitored over a 4-month period, producing over 75 shield cycles of resultant shield loading. Resultant loading is the true measure of support resistance, providing both roof-to-floor and face-to-waste support reactions as well as the location of the reaction on the shield canopy. Observed roof support reactions were analyzed, with particular emphasis on horizontal shield loading, since it is the least understood design parameter. Average, peak, and change in shield loading during the mining cycle are discussed. Correlations among data parameters are examined, as is the distribution of support loading at the headgate and midface. Conclusions are drawn as to the effectiveness of the shield support at this installation. Recommendations are made for further research needs.

Jan 1, 1987

By John A. Breslin

The Bureau of Mines measured respirable dust in coal mines by means of multiple dust samplers worn by persons moving about the mines. The measurements were made primarily to evaluate the effectiveness of certain dust-control techniques; however, for this report, the data have been analyzed to determine the precision of the personal dust-sampling measurements. A total of 68 sets of measurements were available from multiple personal samplers. The measured dust masses were less than 1.0 mg because the sampling times were short. The coefficient of variation calculated from these data was 18.5 pct, compared with coefficients of variation ranging from about 10 to 30 pct, which were calculated from the most precise and extensive data available for fixed-point dust measurements made in coal mines. From this comparison, it is concluded that dust samplers worn by personnel are as precise as fixed-point samplers in measuring respirabe coal dust; the wearing of the samplers by someone moving about a mine does not contribute significantly to the variation in measurements made with these instruments.

Jan 1, 1983

By O. C. Blade

Total sales of diesel fuel in the United States continue to Increase. This growth is due primarily to two causes: More conversion to diesel units by the rail-roads In recent years, and the greater use of diesel engines in trucks, busses, and tractors. Following are some figures on the distribution of the fuel computed from data issued by the Bureau of Mines.2/ [ ] Deliveries of diesel type fuel from refineries totaled 91,522,000 barrels during the first six months of 1955,3/ corresponding figure for 1954 was 91,170,000 barrels. Information on the properties of this engine fuel is very important to the petroleum industry, engine manufacturers, and consumers. To supply such information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of diesel fuel oil produced in refineries in this country.

Jan 1, 1955

By Fred N. Kissell

In This Chapter [The explosibility of methane gas mixtures Effect of pressure and temperature on explosibility Less common sources of methane ignitions The amount of methane stored in coal Forecasting the methane emission rate Layering of methane at the mine roof When the recirculation of mine air is hazardous The importance of higher air velocity in preventing methane explosions and Mine explosions, barometric pressure, and the seasonal trend in explosions] Dealing with methane in mines and tunnels requires knowledge of the circumstances under which dangerous accumulations of methane are likely to occur. This knowledge involves the properties of the gas itself, an awareness of where these accumulations are likely to occur, and facts on how methane mixes safely into the mine air. The other chapters in this handbook address the handling of methane under a variety of specific circumstances, such as at continuous miner faces or coal storage silos. This chapter addresses some broad concepts that serve as a foundation for the suggestions provided in other chapters. THE EXPLOSIBILITY OF METHANE GAS MIXTURES Methane entering a mine or tunnel often enters as a localized source at high concentration. Figure 1–1 depicts a cloud of methane being diluted into a moving air stream. In this illustration, methane enters the mine from a crack in the roof. As the methane emerges from the crack, it progressively mixes with the ventilation air and is diluted. In the event that this progressive dilution reduces the concentration from 100% to 1%,2 as shown in Figure 1–1, the methane passes through a concentration range of 15% to 5%, known as the explosive range. In the explosive range, the mixture may be ignited. Above 15%, called the upper explosive limit (UEL), methane-air mixtures are not explosive, but will become explosive when mixed with more air.

Jan 6, 2006

By T. H. Jeffers

The Bureau of Mines conducted a laboratory investigation of copper electrowinning from electrolytes produced by solvent extraction. The purpose of the research was to gain a better understanding of the fundamental relationship between copper electrowinning conditions, anode corrosion, and cathode purity. Processing variables were evaluated in a cyclic semicontinuous system in which the depleted electrolyte was used to strip copper from loaded organic extractant. For the production of high quality copper cathodes, the electrolyte was dosed with cobalt and stripped of organic solvent extraction reagent. An optimum cobalt addition of 60 ppm, and removal of the entrained extractant with activated carbon provided the best conditions for electrowinning copper containing the least amount of lead and controlling anode corrosion. As little as 13 ppm of the entrained organic extractant, LIX 64-N, significantly accelerated anode corro-sion. However, the addition of 1,000 ppm of organic diluent kerosine did not affect anode corrosion. After cobalt dosing and removing the entrained extractant, cathodes containing less than 2 ppm lead were consistently electrowon at widely varied current densities, electrolyte copper and acid concentrations, and temperatures. Dosing of the electrolyte with selected impurities including magnesium, aluminum, manganese, and iron did not affect the cathode purity. However, 0.05 giL of chloride ions markedly increased anode corrosion and the sub-sequent transfer of lead to the cathode copper.

Jan 1, 1985

By Joseph A. Hrabik

The Bureau of Mines compared the feasibility of mining deep phosphate deposits by a borehole mining system with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 150 ft or greater; however, at 50- and 100-ft thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasiblity of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is employed to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1983

By Wesley T. Holmes

This report describes the second phase of an investigation aimed at obtaining a wider knowledge of the problems involved in smelting titaniferous magnetites. Liquidus temperature measurements were made on selected synthetic slag compositions in the Ti02 -A1203 -FeO-Si02 -CaO-MgO system. Both the hot-stage microscope and the strip furnace (melting-holding-quenching technique) were used during test procedure to determine the effects of CaO, MgO, and SiO2 on the liquidus temperature of slags. The liquidus temperatures of slags studied ranged from 1,241° to 1,900° C. The lowest liquidus temperature for each Ti02 plus A1203 plus FeO weight-percent generally occurred when the difference between CaO plus MgO and Si02 was less than 12 weight-percent. In this investigation substitution of either CaO or MgO for SiO2 and MgO for CaO raised the liquidus temperature of more than 50 percent of the reported base slags when Ti02, A1203, and FeO contents were held constant. The results of this investigation may serve as guidelines for determining flux requirements in smelting a wide variety of titaniferous magnetite concentrates or ores.

Jan 1, 1968

By Murray Jacobson

A method for determining airborne trona dust concentrations using a midget impinger was developed. During sampling, the trona dust, composed of sodium carbonate and bicarbonate, dissolves in the collecting medium (water). Resulting solutions are then titrated using 0.1 [N] hydrochloric acid solution. The mass concentration of the trona sample is determined from a calibration curve relating the volume of acid required for neutralizing a collected sample to the mass of the dust. Test results obtained using this method are equivalent to those obtained using a gravimetric sampling method.

Jan 1, 1971

By J. L. Holman

The Bureau of Mines is conducting research to improve technology for the recovery of strategic and critical metals, such as cobalt, nickel, and chromium, that are lost in bulk and particulate superalloy-type scrap because it has not been possible to process mixed contaminated scrap efficiently. The research approach involves melting and casting mixed superalloy scrap into soluble anodes for electrodeposition of Ni-Co alloys by controlled-potential electrolysis. The initial experimental results described in this report are from electrolytic tests us-ing alloy anodes cast from elemental nickel, cobalt, and chromium, the main constituent metals of superalloys. Baseline data and operating parameters are necessary for Ni-Co and Ni-Co-Cr alloys before detailed experiments can be conducted on the more complex superalloy scrap. This basic research assessed the effects of cathode potential, S04:CI electrolyte ratio, electrolyte pH, stirring rate, deposition time, cathode current density, and chromium concentration on cathode current efficiency, alloy deposit composition, and deposition potential at a cell temperature of 55° C.

Jan 1, 1985

The following report summarizes the results of engineering feasibility studies whose purpose was to assess the probable efficiency, reliability, safety and cost of a number of possible methods for removal of radon gas from the ambient air in underground mines. Fourteen candidate techniques were evaluated. Seven of these were based on specific individual principles, and seven were based on combinations of these principles. The individual principles were as follows: 1. Activated charcoal 2. Organic fluids 3. Semipermeable membranes 4. Molecular sieves 4. Cryogenics 6. Chemical reaction 7. Centrifuge The combinations were: 8. Cryogenics and activated charcoal 9. Cryogenics and molecular sieves 10. Cryogenics and chemical reactions 11. Membrane filters and organic fluids 12. Membrane filters, cryogenics and activated charcoal 13. Membrane filters and chemical reactions 14. Silica and an Organic Fluid

Jan 1, 1975

Provide an unobstructive means of measuring small changes in distance from roof to floor or from rib to rib of a mine opening and the rate of closure in order to help operators of under-ground mines detect hazardous ground conditions. Approach A small ultrasonic measurement system was developed to detect g round movement and define closure rates. How the System Works The system contains two parts: a transducer and a readout device. The small ultrasonic transducer, similar to an audio speaker diaphram, is plucked with an ultrasonic frequency every six seconds. This frequency wave is sent through the air and reflected back to the transducer off any surface at which the transducer is pointed. The amount of time needed by the ultrasonic wave to make this round trip is accurately measured using a precise oscillator / timer and is converted into a measure of distance. The accurate 6-second time interval is used to convert any subsequent changes in the reading to a rate of change in feet per minute. Two readings are then displayed alternately on the readout instrument.

Jan 1, 1984

By Edward M. Kawenski

Float dust deposits in return airways in bituminous coal and lignite mines present a special explosion hazard. Research is in progress at the Bureau of Mines experimental coal mine to evaluate the degree of the hazard and to develop measures for preventing dissemination of dust into the ventilating air current. To determine the extent of this hazard prevailing in operating coal mines, 711 dust samples were collected in 50 mines located in the major coal fields of the United States. The mean quantity of coal and the incombustible content of the dust in the samples were determined. The term "float dust" is used to designate particles smaller than 74 microns in diameter (particles passing a No. 200 sieve) which have settled from the air current. Dust usually found in roadways and in working places is coarser than float dust, and is termed "coarse dust" (particles passing a No. 20 sieve). Variations in amount and incombustible content of coarse dust in a midwestern mine were studied previously.5

Jan 1, 1963

Improve the Bureau-developed system for locating and communicating with miners trapped underground following a mine disaster. Approach Include in the wireless system a portable second-generation transceiver that is more reliable, compact, easier to deploy and operate, and ruggedized to withstand a mine environment. How It Works In an emergency, the new transceiver is snapped onto a caplamp battery for power. (Normally the 1 1/2-pound transceiver is either carried by the miner or is strategically located in the mine.) Its antenna wire, coiled inside the transceiver container, is removed and deployed in a roughly square configuration around a coal pillar or on the mine floor. The antenna consists of 300 feet of lightweight wire, which provides a large magnetic moment while remaining intrinsically safe, The photograph shows the

Jan 1, 1981

By L. A. Haas

In this Bureau of Mines investigation, conditions were determined to form an iron sulfide adherent coating with a metallic golden luster on steel upon anaerobic heat treatment with sulfur. The sulfide formation rate was determined in the temperature range of 105° to 500° C with reaction times up to 68 hours. The optimum temperature and time to form an adhering decorative coating on mild steel was in the range of 105° C for about 70 hours to 285° C for 1 hour. The golden coating consisted of an inner layer of pyrrhotite and an outer layer of pyrite. At temperatures higher than about 300° C, the outer layer thickness decreased owing to the decomposition of pyrite to pyrrhotite.. Small quantities (<0.5 wt-pct) of petroleum oil accelerated the sulfide growth rate. The sulfide coating decreased the corrosion rate of steel in a neutral aqueous medium by a factor of two. The dissolution of pyrite in water was dependent on particle size and surface area with the flat pyrite coatings exhibiting the lowest dissolution rate.

Jan 1, 1974

By Koehler Stout

Many hydraulic backfills are deposited at low density and provide less than optimum support strength to stope walls. This laboratory study shove that fill strength can be considerably increased. Placement methods used to increase the fill strength were the head, vibratory, cementation, double-planed (dblplod), and combinations of these methods. An experimental facility van designed to study the placement cathode and resultant strengths of the fills. Physical property tests made on the fills included laboratory penetration and vane shear plus several supplementary tests, such as grain size distribution and relative density. Test results were compared to fills planed by conventional methods and to those results reported by other investigators. When compared to fills placed by conventional methods, the penetration modulus was increased by 4.3 tines when the uncemented-vibrated-head concept was used and 71 times when the cemented-vibrated-head-dblplod concept was used. Apparently, hydraulically fill strength can be substantially increased. Conceptual mining plans are also included on suggested ways of placing and using high-modulus backfills.

Jan 1, 1979

By W. N. Marchant

[The citrate process for flue gas desulfurization (FGD) is a product of continuing research by the U.S. Bureau of Mines to meet the goal of minimizing the objectionable effects of minerals industry operations upon the environment. The reduction of SO2, in solution by H2S to produce elemental sulfur by the citrate process is extremely complex and results in solutions that contain at least nine different sulfur species. Process solution analysis is essential to a clear understanding of process chemistry and its safe, efficient operation. The various, chemical species, the approximate ranges of their concentrations in citrate process solutions, and the analytical methods evolved to determine them are hydrogen sulfide (~0M to 0.06M) by specific ion electrode, polysulfides (unknown) by ultraviolet (UV) spectrophotometry, elemental sulfur (~0M to -0.001M dissolved, ~0M to ~0.1M suspended) by W spectrophotometry, thiosulfatc (~0M to ~0.25M) by iodometry or high performance liquid chromatography (HPLC), polythionates (~0M to ~0.01M) by thin layer chrornatogrphy (TLC), dithionite (searched for but~ not detected in process solutions) by polarography or TLC, bisulfite (~0M to 0.2M) by iodometry, sulfate (~0M to 1M) by a Bureau-developed gravimetric procedure, citric acid (-GM to 0.5M) by titration or visible colorimetry, glycolic acid (~0M to 1N) by HPLC, sodium (~1.5M) by flame photo¬metry, and chloride by argentometric titration.]

Jan 1, 1980

By Travis Q. Lyday

The other South Pacific islands included in this chapter extend from Papua New Guinea, east of the Indonesian Province of Irian Jaya on the island of New Guinea, to Fiji, straddling the 180° meridian. A number of islands have been omitted from this chapter owing to the fact that their only mineral production remained insignificant to the economy of the respective country or territory. These islands include the French overseas territories of French Polynesia and Wallis and Futuna Islands; the independent states of Kiribati, Tonga, Tuvalu, and Vanuatu; the New Zealand freely associated state of the Cook Islands; and the New Zealand dependency of Niue. The mineral production that did exist in these islands was limited to construction materials such as coral reef limestone, crushed stone, and sand and gravel in minor quantities used solely for domestic consumption. FIJI Fiji, an archipelago in Melanesia consisting of 300 islands ranging from tiny coral atolls, cays, and rugged coral limestone islets to the larger mountainous, volcanic islands of Kadavu, Taveuni, Vanua Levu, and Viti Levu, straddles the 180° meridian about 1,800 kilometers south of the Equator. Fiji has been an independent member of the British Commonwealth of Nations since October 10, 1970.

Jan 1, 1988