Search Documents

By Perry N. Halstead

This report describes two goniometers that, by simple manipulation, can be used to ascertain the attitude of a joint, vein, or fracture plane observed on the planar projection of a borehole photograph taken with an NX borehole camera of the type developed by the U.S. Army Corps of Engineers. One goniometer was designed to interpret photographs taken in vertical drill holes and the other for photographs taken in inclined drill holes. In practice, several measurements are made on each photograph with the goniometer. These data are then substituted into mathematical equations, which are derived in this report and the attitudes of fracture planes are determined.

Jan 1, 1968

By A. G. Starliper

Laboratory studies were made to produce whiskers of tungsten over a wide range of operating temperatures. Hydrogen reduction of tungsten hexachloride in a vacuum furnace at temperatures from 2,7000 to 3,3000 C yielded a small quantity of tungsten whiskers, provided a low degree of supersaturation was maintained. Direct measurements of 3,000,000 to 4,000,000 psi were obtained for the ultimate tensile strengths of individual whiskers averaging 3 to 4 microns in diameter with average aspect ratios of 1,000. This compares with strengths of 300,000 to 400,000 psi for 13-micron-diameter commercial filaments.

Jan 1, 1968

By Eldon C. Pattee

Reconnaisance samples of reported beryllium occurrences in Idaho, Washington, Montana, and Oregon were chemically and spectroscopically tested in a mobile laboratory. The two predominant types of occurrences were green beryl associated with Cretaceous intrusions and disseminated aquamarine associated with Tertiary intrusions. Although the beryllium content of known deposits in the Northwest is too low for economic development at present, total submarginal-grade beryllium resources in pegmatites are estimated to be 570,000 to 1,870,000 tons containing 0.024 to 0.167 BeO. A potential source of 500,000 to 700,000 tons of beryllium-bearing tactite in Idaho and Montana averages 0.033 to 0.080 percent BeO.

Jan 1, 1968

By F. W. Wood

The use of consumable.-electrode arc melting as a production technology is growing. One advantageous feature of this process is that it avoids ingot contamination by soluble crucible materials by employing a chilled metal crucible. Because the thermal balance under these conditions is rather delicate and does not necessarily provide a favorable environment for solidification, catastrophic imbalances can occur. The effectiveness and mechanistic roles of various factors are mostly unknown, and more intelligent insight regarding the distribution of temperature and heat is needed. Experience has provided several pertinent observations, some of which are quite superficial. The most meaningful data have resulted from studies of molten pool shapes and sizes and from measurements of heat flow through crucible walls. Overall experience, intuitively interpreted and supplemented, is sufficient nevertheless as a basis for a boundary-value treatment of the problem. A mathematical analysis based on a separation of variables, using conventional differential equation methods, provides a useful solution. For a cylindrical ingot, the temperature varies as a Bessel function of an argument proportional to the radius and as an exponential function of longitudinal position. Trial calculations using the problem solution seem to verify the general correctness of the result as compared with experience. The role and nature of solution parameters are also clarified, though not entirely resolved. It is revealed that the barrier to heat flow at the ingot-crucible surface has a prominent influence. Utility of the model embodied in the problem solution is readily demonstrated by considering a variety of contemporary questions about arc melting, and it is hoped that utility can be enhanced by improvement of the model.

Jan 1, 1968

By Robert A. Bradburn

The Bureau of Mines has developed a miniature, portable two-level oxygen-deficiency alarm and produced three prototype models. Each operates from a 4.2-v dc power source, and the highest current drain of any model is 80 ma. An electrochemical cell, which produces an electrical output in proportion to the partial pressure of oxygen to which it is exposed, is used as an oxygen detector. The output of the cell is applied to an electronic circuit that detects two different levels of oxygen percentage below that of normal air, and produces distinct audible signals at these levels. The hazard alarm mode is activated when the oxygen percentage first drops below normal and produces a 500-cps "beep" tone with an intermittency of 1 cps. The danger mode produces a continuous 500-cps audible signal when the oxygen percentage drops still lower.

Jan 1, 1968

By Martin H. Stanczyk

Bench scale, laboratory batch attrition grinding tests were made of a coarse commercial kaolin in a stainless steel, 5-inch-diameter attrition grinding machine to study the effect of a number of basic operating variables on particle size reduction and electric energy consumption. The results of the investigation showed that the more important operating variables influencing the efficiency of kaolin comminution and energy consumption requirements were type, size, and shape of grinding media, grinding media to clay weight ratio, peripheral rotor speed, clay slip pulp density, degree of pulp dispersion, and the angular arrangement of the rotor and stator bars. The tests also indicated that variables having less influence on grinding efficiency and energy consumption were pulp temperature, design of rotor cage, rotor clearance, rotor-stator bar interval, addition agents, pulp level, degree of pulp aeration, and chamber liners. The research showed that grinding media had the greatest influence on abrasion of machine parts and that spherical-shaped grinding media were superior to sharp angular or long bladed media with respect to media degradation, machine abrasion as well as grinding efficiency.

Jan 1, 1968

By John Ward Smith

The Bureau of Mines drilled Wyoming Corehole No. 1 in Sweetwater County, Wyo., to sample Green River Formation oil shale. Core obtained was assayed for oil yield to determine richness and stratigraphic distribution of oil shale in the deposit. Oil shale in place at Wyoming No. 1 site represents over 200 million barrels of oil per square mile. Additional data useful in evaluating the deposit, including generalized stratigraphy and mineralogy, detailed lithologic descriptions of the core, rock specific gravity, and bore-hole logs, are presented with the oil-yield data. The sampled Wyoming oil shale resembles Mahogany-zone oil shale in rock properties and gross mineralogy. A statistically derived equation relating shale density to oil yield for the Wyoming deposit compares with a similar relationship valid for the better known Mahogany-zone oil shales in Colorado and Utah. A density log from Wyoming Corehole No. 1 is calibrated for direct oil-yield logging. The alternating rich and lean beds of shale at this site may permit creating the permeability necessary for direct production of shale oil from the shale in place.

Jan 1, 1968

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clay, Gilmer, and Lewis Counties, W. Va. In 1966, almost 1.3 million tons of coal was mined in these counties, of which more than one-half was from the Pittsburgh coalbed. Washability analyses were made of 16 coalbed samples. Of these, only 11 samples could be upgraded to metallurgical quality. For steam or power generation five of the coals were of low sulfur content as received. The remaining samples were generally of medium sulfur content even after upgrading.

Jan 1, 1969

By Edward W. Parsons

To determine in what part and to what extent creep or movement exists in an installed rock-bolt anchor and the effect of the creep or bleedoff on the tension load on a rock bolt, as well as the effect of normal mining activity on the rock-bolt load and anchor, the Bureau of Mines conducted tests in the laboratory and in two mines using four types of expansion-shell anchors, the wedge bolt, and in one mine, explosive-anchored rock bolts. Specially mounted heavy-duty springs, calibrated to obtain load readings from spring movement, were installed on the test bolts to prevent a drastic reduction in tension load caused by slipping or seating of the anchor. A dial gage, reading to 0.0001 inch, measured movement of the anchor shell against the rock and seating of the anchor wedge plug in the shell. While all bolts had electrical resistance strain gages for load reading, only readings from the laboratory tests were used because those from the field tests were erratic. The tests revealed that most load loss resulting from static loading is due to the slippage and seating of the serrations on the anchor shell into the drill-hole wall. Dynamic loading, primarily from sudden shocks from nearby blasting, and possibly from ground movement or mining activity, will cause the anchor wedge plug to seat in the anchor shell.

Jan 1, 1969

By G. H. Keith

Oxygen and nitrogen cause strain aging in electrorefined vanadium, as evidenced by maxima in yield and tensile strengths and by Snoek internal friction peaks. Alloys containing up to 0.22 percent oxygen and 0.11 percent nitrogen were investigated. Tensile strengths of oxygen-and nitrogen-containing alloys were 66,000 and 68,000 psi at 300° to 400° C, compared with 53,000 and 62,000 psi, respectively, at room temperature. Total elongation decreases to about 7 percent at the temperature of maximum strength. At 600° C, strain aging is not evident. Based on interstitial contents calculated from internal friction measurement, the increases in strength caused by nitrogen and oxygen were 440,000 psi per weight-percent nitrogen and 260,000 psi per weight-percent oxygen. Application of the Schoeck and Seeger treatment to the Snoek effect in these systems results in a calculated lattice distortion of 0.24 and 0.15 caused by the presence of an interstitial nitrogen or oxygen atom, respectively. Alloys containing boron or carbon were also investigated. Both elements refine the grain size but have no other effect because of their low solubility in vanadium.

Jan 1, 1969

By James V. Luxner

The airflow and methane distribution patterns developed in an equipment-free entry 6.5 feet high and 12 feet wide, ventilated by line brattice operated blowing to or exhausting from the face, were determined by the Bureau of Mines for varying conditions. Results of these studies show that blowing line brattice systems of face ventilation are more effective than comparable exhaust systems. The face ventilating efficiency of any line brattice system is dependent upon the method of ventilation, the face distance, the tight rib distance, the volume of air delivered to the end of the line brattice, and the volume of methane released at the face. Experimental results indicate that maximum face ventilation efficiency is achieved when the inby terminus of the line brattice is installed 5 feet from the face and at a distance less than one-third the entry width from the nearest rib. Analyses of data are based upon the ability of a face ventilation system to dilute methane in the immediate face area.

Jan 1, 1969

By Verne E. Hooker

In situ stresses, based on isotropic and anisotropic relations, were evaluated using computer techniques from overcoring data obtained in dimension stone quarries along the Appalachian Piedmont, the Ozark Uplift, and the Ouachita Tectonic Belt. Stresses in the horizontal plane near the surface are compressive and range from 100 to 4,500 psi. The direction of maximum compressive stress seems to be alined with the general tectonic structure for most of the determinations. The ratio of the maximum to minimum elastic parameters in the horizontal plane ranges from 1.05 to 2.46 for these competent rocks. Isotropic versus anisotropic stress determinations show differences only as great as 25 percent in stress magnitude and 25° in orientation.

Jan 1, 1969

By Thys B. Johnson

Operations Research techniques for determining optimal shipping schedules and production and product allocation are discussed. A hypothetical mining operation model is formulated by the Bureau of Mines, and optimal production and product allocation are determined. The technique of sensitivity analysis is discussed and is used to illustrate the effect of the variability in a mining operation on the optimal production and product market plan.

Jan 1, 1969

By Manuel Gomez

The Bureau of Mines used data from 31 core samples to develop prediction equations for evaluating chemical and carbonization properties of six seam units in a lignite deposit approximately 2 miles wide and 8 miles long in the Wilcox Formation of central Texas. Statistical response surfaces, based on core analyses, were computed for 14 parameters indicative of lignite quality. These computed surfaces, and their mathematical equations, can be used to predict values of the selected properties of the lignite seams at any desired surface coordinate position between core hole locations. The wide range of application shown by this study indicates that the methods of statistical regression analysis may be useful to evaluate large deposits of lignite or higher rank coal.

Jan 1, 1969

By Charles Prasky

The Bureau of Mines investigated the conversion of nonmagnetic iron minerals to magnetic form through reduction Toasting operations. The primary objective was to obtain a concentrate that could be used as a direct shipping material for blast furnace consumption. Crude iron materials from the Steep Rock Lakes, Ontario, area were prepared into a blend of 8 parts siliceous ore, 3 parts pyritic ore, and 1 part tailings. Experimental work included laboratory reduction roasting tests, two continuous 10-day campaigns, and one 12-hour test all in a 34-inch by 36¬-foot rotary kiln. The objective of the project was achieved in producing an iron concentrate containing about 66 percent iron with over 90 percent iron recovery. Desirable operating conditions were developed in the kiln but optimum process variables were not completely established.

Jan 1, 1969

By K. R. Dorman

To further investigate the potential of precast concrete sets as a support medium for underground mines, the Bureau of Mines designed a five-piece precast concrete drift set for a small opening and tested it to destruction in a straining frame. Twenty-seven tests were made with three sizes of members using three loading conditions. In addition, six tests were made with sets in a distorted configuration, Test results and typical failure patterns are presented. A comparison of results with those previously reported for the three-piece set shows the five-piece set supports considerably larger total loads than does the three-piece set of equivalent cross section designed for the same size of opening. Recommendations are made for improvements in design.

Jan 1, 1969

By G. V. Sullivan

The Bureau of Mines conducted preliminary beneficiation studies of a gold-bearing graphitic schist from Blue Hill, Tallapoosa County, Ala. The average analysis of the material was 0.08 oz/ton gold. Tabling of minus 35-mesh material recovered 83 to 94 percent of the gold at grades of 6.925 to 2.165 oz/ton, respectively. A combination of jigging and tabling resulted in a concentrate assaying 24.3 oz/ton gold and contained 87 percent of the total gold. Treatment of the material by jigging, tabling, and amalgamation recovered 86.5 percent of the gold.

Jan 1, 1969

By J. M. Singer

The Bureau of Mines investigated the threshold of dispersal of monolayers and piles of rock dust, anthracite, and Pittsburgh seam coal dust in a small wind tunnel that simulated a coal mine gallery, with the objective of preventing or limiting the formation of flammable dust clouds. The effect of selected variables on entrainment velocity was examined. Mode of entrainment and flow processes in the wake region of dust configurations were investigated by means of high-speed motion pictures. Significant results were as follows: 1. Local minimum air velocities required for dispersal were only slightly higher for shallow dust ridges than for dust particles. 2. Minimum velocities for entrainment of dust particles from smooth glass and coal surfaces increased in the order rock dust, anthracite, Pittsburgh seam coal. 3. The mechanism for dispersal of dust poles depended significantly on dust pile geometry, cohesiveness of dust, bulk density and compaction of dust, adhesive surface, and vibrations perturbing the supporting surface.

Jan 1, 1969

By R. E. Siemens

The Bureau of Mines sought to correlate the variation of structure-sensitive superconducting properties with microstructure in selected Cb-Hf alloys and to compare the experimental results with those predicted by the GLAG theory. Alloys in wire and rod form were evaluated by critical temperature, critical current, magnetization, resistivity measurements, and optical and electron microscopy. In the absence of an external magnetic field, the current carrying capacity of columbium was greatly reduced with addition of up to 85 wt pct Hf, but a large increase in Ic occurred for Cb-90 wt pct Hf. Favorable Ic-H behavior was observed in cold-drawn alloys containing 25 and 57 wt pct Hf. Correspondingly, a maximum in Tc occurred at 10-25 and 90 wt pct Hf. Four- or five-hour heat treatment at 600° C resulted in maximum Ic values and maximum hysteresis in magnetization. Dislocation pileup, polygonization, and fine precipitates, responsible for flux pinning, are listed in order of their effectiveness as pinning sites. Sites having an average separation of 1,500 to 3,000 A and a diameter of 1,000 A or less were most effective in influencing Ic-H and M-H behavior. The resistive critical fields increased smoothly to a maximum of 80 k0e between 60 and 65 wt pct Hf. Highfield, mixed state, reversible paramagnetism was observed in some alloys; however, the GLAG theory was in good agreement with experimental results for the majority of the composition range studied.

Jan 1, 1969

By Karl C. Dean

The Bureau of Mines stabilized 10 acres of windblown copper mill tailings at McGill, Nev., by a combination chemical-vegetative procedure. Legumes, winter wheat, wheat-grasses, and wild rye were seeded, and the area was subsequently sprayed with a resinous adhesive chemical to stabilize the sands until the vegetation could grow. During the year since treatment, the area has been well stabilized against wind erosion. The established vegetation appears to be capable of self-perpetuation and renewal without irrigation. The cost of stabilizing the area was $135.50 per acre.

Jan 1, 1969