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By P. C. Good

The Bureau of Mines conducted a laboratory investigation of a sinter-leach method to recover aluminum and fluorine from waste carbon potlining residues from secondary cryolite recovery operations in aluminum reduction plants. After removal of carbon by burning, the residue was sintered at 900° to 1,100° C with silica and N2CO3, then crushed and leached with dilute NaOH solution, dilute Na2C03 solution, water, or water containing residual Na2O which remained in the sinter after reaction and decomposition of Na2CO3. Over 90 percent of the contained aluminum and up to 87 percent of the contained fluorine were extracted from this waste product in the form of a mixed alkaline solution. Treatment of the alkaline solution with CO2 yielded a white precipitate containing 89 percent of the original aluminum and 61 percent of the original fluorine as a mixture of synthetic cryolite and alumina, together with a variable excess of soda.

Jan 1, 1969

By R. L. Crosby

The Bureau of Mines investigated alloys of copper with 2, 3, and 4 vol pct alumina and with 2 vol pct yttria. Alloys were prepared by a coprecipitation process and were fabricated by pressing and sintering of powders, extrusion, and swaging. Tensile properties at room and elevated temperatures, stress-rupture strength, electrical conductivity, and density were measured. The superiority in elevated temperature strength of dispersion-strengthened copper to OFHC copper was confirmed. Increasing the oxide content from 2 to 4 vol pct produced only a small improvement in strength properties and decreased the electrical conductivity. The 3 vol pet alumina alloy had the best overall combination of properties.

Jan 1, 1969

By P. G. Clites

The Bureau of Mines developed techniques for induction melting of titanium in a split, water-cooled copper crucible. Calcium fluoride, which was used as an inert slag cover during melting, formed an insulating layer of solid slag between the ingot and the crucible wall. This thin layer of slag effectively insulated the ingot from the crucible and prevented the molten metal from shorting across the slits between adjacent segments of the crucible. The technique provides a means of melting loose titanium sponge and scrap and eliminates the need for fabricating a consumable electrode. This report describes the equipment developed and compares ingots produced from two varieties of titanium sponge, from titanium scrap, and from previously melted titanium with ingots prepared by vacuum-arc melting and electroslag melting. A melting scheme was also proposed and evaluated whereby loose titanium sponge was consolidated into a first-melt ingot for vacuum-arc remelting.

Jan 1, 1969

By Carl F. Wingquist

In support of Bureau of Mines studies of thermal fragmentation of rock, the elastic moduli of four types of rock were measured at temperatures ranging from room temperature up to 1,500° F (1,089° K). The sonic method was employed to determine the resonant frequencies of the rock specimens and from these frequencies, the elastic moduli were calculated. Data for Young's modulus, shear modulus, and Poisson's ratio are given as a function of temperature for Dresser basalt, Reserve taconite, Jasper quartzite, and Charcoal granite. Young's modulus and the shear modulus decreased with increasing temperature up to about 1,200° F and then became relatively insensitive to temperatures from 1,200° to 1,500° F.

Jan 1, 1969

By Merle L. Bowser

The Bureau of Mines has developed a portable recording methanometer that utilizes the Bureau's methane sensor. The methanometer can operate continuously for at least 30 hours on small, sealed, rechargeable lead-acid batteries.

Jan 1, 1969

By R. K. Koch

The vapor pressures of liquid titanium and liquid platinum were studied under the Bureau of Mines program for the determination of thermochemical data on the transition elements. Beating was done in a 2-kw electron-beam furnace with a water-cooled copper crucible to contain the melt. Temperature was measured with a disappearing-filament brightness pyrometer. The vapor pressure data for liquid titanium in the range 2,008° to 2,379° K are represented by the least-squares derived equation [log p (atm) = 6.268 - 22, T] Two series of determinations were made on liquid platinum. Results of the first series are expressed by the least-squares derived equation [log p (atm) = 8.240 - 30,460T] for the range 2,0860 to 2,4200 K. Results of the second series are expressed by the least-squares derived equation [log p (atm) = 7.795 - 29,580 T] in the range 2,045° to 2,442° K. Third-law evaluations of each series gave mean standard heats of sublimation of 112.4 kcal/mole, 133.3 kcal/mole, and 133.8 kcal/mole for titanium first series on platinum, and second series on platinum, respectively. Second-law heats of sublimation and equations for heats, free energies, and entropies of vaporization were obtained from sigma plots of each data set.

Jan 1, 1969

By K-H. Frohne

This report presents a study of the Cooper sand of the Fork Run pool of Warren and McKean Counties, Pa., and a prediction of the secondary oil recovery by gasflooding the reservoir. A computer program employing a modification of the Craig, Geffen, and Morse secondary recovery calculation was used to make the gas flood performance forecast and is presented in the appendix. The Cooper sand reservoir in the Fork Run pool lies at a depth of about 1,900 feet and covers an area 1/2 mile wide by 2-1/4 miles long. Original oil in place is estimated to have been 8,266,000 STB. The primary recovery mechanism is solution gas drive, and ultimate primary recovery may reach 20 percent over a well life of 90 years. Two computer predictions were made for gas flooding the Cooper reservoir. The first was for a 25-acre pilot five-spot utilizing existing wells, but project economics were poor since only 25 percent of injection gas is utilized for pilot oil recovery. Recovery was 71,000 STB, or 22 percent of oil in place at flood initiation, but required 25,700 scf gas injected per STB of oil recovered. In the second prediction, pilot area performance was projected for the entire Fork Run pool, and economics became good. Recovery was 1,753,000 STB from 25 five-spots after the injection of only 6,400 scf per STB of oil recovered.

Jan 1, 1969

By M. O. Serbousek

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed an eight-piece precast reinforced concrete drift set for a small opening. Twenty-two sets of three different member sizes were tested to destruction under two loading conditions. A discussion of the test results and typical failure patterns is presented.

Jan 1, 1969

By J. S. Miller

The Bureau of Mines conducted surface tests to determine the feasibility of using liquid explosives for underground rock fracturing. The effects of configuration, confinement, length, critical layer thickness, and fracture-propping sand on detonation and explosive propagation velocity of desensitized nitroglycerin were studied, using polymethyl methacrylate and glass-plate reservoirs through lengths from 3 to 12 ft, with explosive-layer thicknesses from 0.1875 to 0.0312 in and in aluminum tubes 8 ft long with diameters from 2.000 to 0.125 in. Interval and continuous detonation velocity data were obtained. Under the test conditions detonation velocity was dependent upon explosive confinement and fracture-propping sand. The detonation velocity of a confined nitroglycerin explosion in aluminum tubes can be reduced by as much as 85 percent, when the tube contains fracture-propping sand. The shape of the reservoir, whether triangular or rectangular, has little effect on the detonation velocity or explosive propagation. The critical or minimum explosive-layer thickness between glass plates, capable of supporting propagation, was 0.0312 in. The presence of a fracture-propping sand in the sheetlike layers increased the critical explosive layer thickness to 0.0625 in. In nitroglycerin-filled and nitroglycerin-sand filled tubes, the minimum tube diameters successfully tested were 0.125 in and 0.375 in, respectively.

Jan 1, 1969

By R. S. Fowkes

The Bureau of Mines constructed a fully automated pilot plant facility to study the hydraulic transportation of solids through a lock hopper feeder system. An equation for the energy requirements to transport coarse solids hydraulically proved applicable to this system. Optimum velocities were obtained for limestone, mine refuse, and bituminous coal. The experimental data, calculations, and graphs show the effect of velocity, specific gravity, and solids concentration on head loss and power requirements. Other data were obtained and evaluated to determine the effect of particle size on head loss. Results also are given for (a) tests using friction reducing polymers; (b) tests using seven test sections of steel alloy pipe to determine their wear characteristics; (c) tests to determine spatial segregation of moving particles; and (d) tests to determine the effect of shape, size, and specific gravity on particle velocity in a horizontal pipeline. The lock hopper feeder system was found practical for continuous hydraulic transportation of the material types and size ranges tested.

Jan 1, 1969

By M. M. Tilman

In a Bureau of Mines investigation to develop lead alloys with improved tensile strength and creep resistance, lead-base alloys containing cadmium and antimony in nominal 1-to-1 atomic ratios were melted in air, cast, and rolled into sheet to 90 percent reduction at temperatures varying from room temperature to 175° C. Tensile testing at room temperature and stress-rupture testing at 900±3° F were conducted on the as-rolled alloys. The best tensile properties were observed in an alloy of Pb-4.2 wt pct Cd-4.5 wt pct Sb which exhibited an average tensile strength of 7,270 psi with 36 percent elongation in 2 inches. An alloy of Pb-5.5 wt pct Cd-6.0 wt pct Sb had 100-hour stress-rupture values of approximately 2,100 psi and 1,000-hour values of approximately 1,700 psi.

Jan 1, 1969

By John Ward Smith

An analytical method developed by the Bureau of Mines to determine dawsonite, nahcolite, and nondawsonite alumina (called excess alumina) extractable from Green River Formation oil shales is presented. The method requires water extraction of nahcolite followed by HCI-extraction of dawsonite and an unidentified mineral yielding excess alumina from the water-leached residue. Instrumental determination of sodium in the water extract and sodium and aluminum in the HCI extract measures the sample's content of the minerals. Detailed evaluation shows the method to be adequately specific, precise, and reproducible and free from uncorrectable interferences. The method's results define precisely the production of sodium carbonates and alumina possible from a sample of oil shale and the interval it represents. Shale-oil yields, nahcolite contents, and yields of extractable alumina determined on 83 samples representing an 821-foot section of dawsonite-nahcolite-bearing shale from .Colorado Corehole No.3, drilled in the north part of Colorado's Piceance Creek Basin, are presented. These samples resulted in nahcolite contents to 53.3 percent, oil yields to 48.3 gallons per ton, and alumina yields to 5.80 percent. Use of these data to evaluate the production potential of a section of the formation are suggested.

Jan 1, 1969

By Richard Havens

Acidic and basic uranium leach plant residues located on the Navajo Indian Reservation, Tuba City, Ariz., were successfully stabilized against wind erosion using a relatively low-cost chemical method. An elastomeric polymer chemical was applied to the dike areas and a calcium magnesium lignosulfonate to the beach areas of three tailings ponds. The water-soluble chemicals were applied with an automated sprinkling system. The stabilization cost was $335 per acre for the 34.5-acre tract.

Jan 1, 1969

By Danton L. Paulson

Elevated temperature electrical resistivity measurements were made by the Bureau of Mines on arc-melted, spin-cast, and hot-pressed columbium carbide¬carbon (CbC-C) and zirconium carbide-carbon (ZrC-C) materials up to 2,000° C. The CbC-C materials displayed electrical resistivity values ranging from 35.20 microhm cm at 23° C for hot-pressed material containing 12 wt pct carbon to 242.64 microhm cm at 1,622° C for arc-cast material containing 17.0 wt pct carbon. Electrical resistivity values ranged from 29 microhm cm at 20° C for arc-cast ZrC-C containing 16 wt pct carbon to 279 microhm cm at 1,951° C for hot-pressed ZrC-C containing 21 wt pct carbon. Data from a previous report were included to establish comparison between the electrical resistivities of the CbC-C, ZrC-C, and HfC-C systems.

Jan 1, 1969

By M. M. Fine

Research on the solid-fuel reduction of Knob Lake iron or was conducted to upgrade lean and high-grade ores and recover metallized products suitable for ironmaking or steelmaking. The program included bench-scale tests plus a number of continuous campaigns in a 34-inch by 36-foot rotary kiln. In the laboratory, metallizations in excess of 90 percent were achieved by reduction of crushed ore with lignite at 950° C. Subsequent grinding (to minus 200 mesh) and wet magnetic separation yielded concentrates analyzing less than 3.0 percent SiO2 and more than 90 percent Fe. Virtually complete recovery of the iron occurred. During early continuous tests the crushed ore created a serious ringing in the kiln which was solved by balling the fines with bentonite. Unfortunately, at this temperature (950° C) the bentonite militates against the concentratability of the metallized product. For example, a run on direct-shipping ore produced concentrates of 89.5 percent Fe and 4.5 percent SiO2. At 500° C the adverse effect of bentonite disappeared and concentrates of 88.4 Fe and only 2.5 percent SiO2 resulted. However, with comparable feed r Los, the metallization dropped to 73 percent.

Jan 1, 1969

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

By Donald C. Strimbeck

The Bureau of Mines designed a down-fired refractory-lined combustor that efficiently burned pulverized coal to produce a gas suitable as working fluid for an open-cycle gas turbine. The gas contained relatively little carbon, so the load on the ash-separation equipment was significantly reduced. Moreover, reduction in carbon content of the gas increased the average density of the solid particles making them more amenable to removal by centrifugation. Centrifugal-type separators failed to remove sufficient ash; however, to limit blade wear enough to achieve operating periods generally deemed necessary for commercial practicability.

Jan 1, 1969

By C. A. Komar

The Bureau of Mines conducted oil-displacement tests in the laboratory with three water-in-oil and five oil-in-water emulsions that were created with ultrasonic energy at a frequency of 20 kHz and an acoustic intensity of approximately 100 watts per cm2. Emulsions of either crude oil or kerosine, brine, and 112 to 2 percent emulsifier were formed during 30 seconds of acoustic irradiation. Results indicate that ultrasonic energy induces greater and more uniform dispersion of one liquid in another in the presence of small amounts of chemi¬cal emulsifiers. When the emulsions were injected as a buffer slug before waterflooding, recovery of the oil-in-place was 8 to 22 percent greater than with conventional waterflooding in the test specimens, regardless of the con¬tinuous phase (oil or brine). The emulsions do not appear to be applicable to the Appalachian area; however, because the oilfields are too "tight," the clays in the formation remove the emulsifier from the displacing fluid, and not enough additional oil is produced, compared with recovery using conventional waterflooding, to warrant the increased operating costs.

Jan 1, 1969

By Clarence O. Babcock

Model pillars of limestone, marble, sandstone, and granite with length-to-diameter (L/D) ratios of 3, 2, 1, 0.5, and 0.25 (0.286 for granite) were tested to failure in axial compression to determine to what extent an increase in end constraint increased compressive strength. Adjustable steel rings, mechanically tightened about the ends of test specimens to create a radial prestress of 3,000 or 5,000 psi prior to the application of axial load, increased end constraint more than was possible in previous tests using solid steel rings. (Solid rings, epoxy-bonded to the ends of dogbone specimens, increased compressive strength compared with that of straight specimens without ring constraint.) During the loading cycle, additional end constraint was produced by lateral expansion of the specimens against the rings. The effect of the end constraint was to increase the compressive strength 55 to 58 percent for the shorter pillars of dogbone shape compared with the compressive strength of straight pillars with the same L/D ratios without ring constraint. Most pillars with L/D ratios of less than 2 were made stronger by end constraint. Pillars with an L/D ratio of 3 did not benefit significantly from end constraint. When the results from compression testing of straight specimens of rock in the laboratory are used to design mine pillars in situ, the pillars will be larger than necessary if the horizontal compressive stress is several thousand pounds per square inch greater than that resulting from the weight of the overlying rock alone. The L/D ratio can be increased by a factor of 1.76 for ratios in the range 0.25 to 3 and still provide the same compressive strength. The safety factor applied with straight specimen test results should also be acceptable for use with constrained pillar test results.

Jan 1, 1969

By S. E. Khalafalla

The Bureau of Mines investigated the metallothermic reduction of copper oxide as a function of temperature, reactant proportions, form of reductant, and gaseous environment, using iron and steel scrap reductants. The reaction proceeded rapidly with powdered iron at temperatures above 560° C, attaining over 95 percent copper metallization within 3 hours. The importance of inter-reactant contacts on the extent of the reaction was evident from the variable, but usually lesser, degree of metallization obtained with iron from tin cans and automobile steel scrap. Reduction decreased as the molar ratio of copper to iron increased between 1 and 3. The most favorable gaseous environment for the reaction was a static helium atmosphere containing about 0.6 percent water vapor. Ferrothermic extraction of copper from its oxides appears to be essentially a "solid-state cementation" process. While ordinary cementation processes must be preceded by leaching, the ferrothermic method avoids this generally slow step and also the water pollution caused by the leaching agents. Sulfidic copper concentrates could likewise be reduced with metallic iron following their complete oxidative roasting.

Jan 1, 1969