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By S. H. Lorain

This paper is one of a series on mining and milling method and costs being published by the United States Bureau of Mines. The Golden Messenger mine, operated by the United Gold Mines Corporation, is in the York-Confederate Gulch mining region in Luis and Clark County, Mont., 22 miles northeast of the city limits of Helena and about 1 mile north of the town of York. It is the first operation to exploit successfully the low-grade ores of the York-Confederate Gulch area. The unusual vein structure presents some mining problems that have been solved in ail interesting manner.

Jan 1, 1937

By D. Harrington

Notwithstanding all the effort maa.e to introduce wet drills to prevent dustiness of air of metal-mine workint;s pl2.ces, there has during the pa.st few years arisen in Australia and South Africa an impression that wet drills, in­cluding the Leyner typa, actuali"y cause und..ue quantities of finely divided ore and rock to rise into the air, these fine particles being chiefly attached to · P=i-rticles of fog or spray escc:.ping frow holes using water drills. This fs saia. to have created consternation in the ranks of the min operators who have com­piiei With drastic wet dri llin rf,ubtions, 2nc:i. purchased and operateC1. various types of wet drills at no inconsiderable expeniiture in both money and effort.

Mar 1, 1922

By James R. Welty

Heat content values were experimentally determined for yttrium metal between temperatures of 400° and 1,300° K and for iron pentacarbonyl between 301° and 380° K. The drop technique was used; that is, a sample of material sealed in a protective capsule was heated to 3 desired temperature in a furnace and then dropped into an ice calorimeter. A revised technique for determining heat content values from calorimetric data is described. Heat content and corresponding entropy-increment data above a reference temperature of 298.15° K are presented in tabular form. Equations for heat content and heat capacity as functions of temperature were derived for each substance. These equations are [Y (c): HT-H298.15 = 1.2041T 1 3.393 x 10-3T2- 0.4176 x 10' T"1 + 739.9 cal/mole Cp = 1.2041 + 6.786 x 10-3T + 0.4176 x 106-T-2 cal/deg mole Fe (CO) E, (1) : HT - H298.15 = 55.636T - 16,588 cal/mole Cp = 55.636 cal/deg mole]

Jan 1, 1963

By H. Tomlinson

The development of the Sevier Valley Coal Co.'s mine marks the opening of the Salina Canon coal district in Utah. The mine is favorably located with respect, to the existing markets of the West, and if the present estimates of the amount of workable coal in it are accurate it has many Important advantages in favor of its development. This mine is situated 18 miles east of the town of Salina, Sevier County, Utah, which at present is the nearest shipping point oh the Marysvale branch of the Denver & Rio Grande Western Railroad, and is about 152 miles south of Salt Lake City, which is the distributing center for much of the coal from the Carbon - Emery coal field and is the place from which nearly all Utah coal shipped to San Francisco and points on the northern Pacific coast has a common haul.

Jan 1, 1930

By H. W. Wainwright

1. A schematic diagram and a description of the apparatus are presented. 2. Five runs were made using gas having a hydrogen-carbon monoxide ratio of about 2:1 and sulfur concentrations ranging from nil to 1.53 grains per 100 std. c.f. 3. At constant space velocity of synthesis gas the product of the sulfur concentration and days of operation, with conversion of H2 + CO above 97 percent, was constant. With a gas containing 0.04 grain of sulfur ac carbonyl sulfide per 100 std, cu. ft ,, the conversion of H2 + CO remained over 97 percent for 40 days. During that time the heating value of the product gas (on a C02-free basis) remained relatively constant at 940 B .t .u. per c.f., based on dry gas measured at 600 F. and 30 inches Hg.

Jan 1, 1954

By Ronald D. Hill, Elmore C. Grim

The removal of overburden often exposes pyritic materials (iron disulfide). As shown in equations 1 and 2, the oxidation of this material results in the production of ferrous iron and sulfuric acid. The reaction then proceeds to form ferric hydroxide and more acid, as shown in equations 2 and 4. [ ] Consequently a low pH water is produced (pH 2-4.5). At these pH levels, the heavy metals such as iron, manganese, copper, and zinc are more soluble and enter into the solution to further pollute the water. Water of this type supports only limited water flora, such as acid-tolerant molds and algae; it will not support fish life, destroys and corrodes metal piers, culverts, barges, etc., increases the cost of water treatment for power plants and municipal water supplies, and leaves the water unacceptable for recreational uses. The amount, and rate of acid formation, and the quality of water discharged are a function of the amount and type of pyrite in the overburden and coal, time of exposure, characteristics of the overburden, and amount of available water(l). Crystalline forms of pyritic material are less subject to weathering and oxidation than amorphic forms. Since oxidation by oxygen is the primary reaction during early acid formation, the less time pyritic material is exposed to air, the less acid is formed. Thus, a positive preventative method is to cover pyritic materials as soon as possible with earth, which serves as an oxygen barrier. In terms of mining, this step is accomplished by current reclamation techniques and small open pits.

Jan 1, 1974

By Guy A. Johnson

Despite the use of warning alarms to alert miners to the backward movement of large mining equipment, miners still are injured too frequently in backup accidents. Currently approved backup alarm technology consists of continuous sounding alarm systems. New technology has developed a warning system that initiates an alarm only if there is an object close behind the vehicle. This advancement eliminates constant exposure to the alarm because a warning is given only in case of a potential collision. Adoption of this development can improve safety and reduce damage, especially for front-end loaders (FEL's). It will also eliminate a source of nuisance noise in urban and residential areas. This Bureau of Mines report describes the general characteristics of infrared (IR) light, ultrasonic wave, and Doppler radar technology as used for backup alarms, and reviews the testing of the most promising detection devices.

Jan 1, 1986

By Bowles Oliver

"Modification of Quarry Process.Limestone beds are formed by processes of nature, processes that have been in operation for thousands and perhaps millions of years. Therefore, their com- position and physical properties are long-established and unalterable features over which man has no control. He must take them as he fields them.It is undoubtedly true that the character of lime depends largely on the nature of the parent limestone. A high-calcium lime cannot be manufactured from a dolomite, nor can a pure lime result from the calcination of an impure raw material. However, in the process of turning limestone into lime man is not entirely helpless in his control of quality. Even though a deposit is variable in character a single lime product of uniform quality may be produced by judicious quarrying. A single grade of product may not always be desired, the producer may wish to supply the needs of a variety of users each demanding U different grade or quality of lime such a series of graded products may be produced in part at least by modifying the quarry method. Thus, by changes in quarry practice a single product or a variety of products may be made. The latter problem will be considered at a later time, and the present paper devoted to the first named question' that of producing a single grade of lime from a deposit of variable rock,It is realized of course that uniformity in the product is influenced greatly by manufacturing processes such as calcining' hydrating' grinding or storage, but the present discussion is confined to the influence of raw materials only. In considering the various devices that may be employed it is realized that much remains to be learned, and it is hoped that many operators will contribute to the discussion as they have already done in connection with previous papers of this series."

May 1, 1923

By James J. Olson

The Bureau of Mines recorded and analyzed overpressure levels for three production blasts at the White Pine copper mine, Upper Michigan, to obtain representative data from single-heading blasts in a long, straight haulageway and to estimate the damage potential inherent in production blasts fired in close proximity to underground structures. Commercial pressure gages with a flat response to 1 kHz were used with an FM tape recorder to record the overpressures from one dynamite and two AN-FO (ammonium nitrate-fuel oil), 500-msec production blasts having zero-delay charge weights of about 75 lb (34 kg). The recorded waveforms from the underground blasts (1) were more complex than the typical free-air wave, (2) were of longer duration, and (3) had numerous secondary arrivals due to reflections from the ribs and roof. The waveforms showed that the zero-delay charges produced the only high overpressures. First pulse peak overpressures from the blasts ranged from 0.10 lb/in2 (6.9 X 102 N/m2) at a distance of 471.1 ft (144 m) to a maximum of 1.76 lb/in2 (121.3 X 102 N/m2) at 191,7 ft (58.4m) from the blasts. An analysis of variance of the first pulse overpressures from the three White Pine blasts showed that no statistically significant difference existed among the overpressure levels from the dynamite and AN-FO blasts and that a single equation P = 4.9 x 103 (D /W1 / 3) 2 .15, where P = overpressure in pounds/inch2, D = d-stance from the blast in feet, and W = zero-delay charge weight in pounds, could be used to describe the falloff of overpressure with distance.

Jan 1, 1971

Develop a method for recovering phosphate from a wide variety of complex western phosphate materials, including low-grade ores, tailings, and unused fines. Approach A flotation technique is used for this broad type of extraction. The method includes depression of phosphate minerals and anionic flotation of carbonate minerals, followed by cationic flotation of silicate minerals. How It Works A slurry is prepared for flotation by sizing to remove a low-grade, high-impurity slime fraction. Depending on the material, further sizing and/or grinding steps may be used to produce a size concentrate or to remove gangue. The flotation feed is conditioned with H2SiF6 and a fatty acid emulsion. The H2SiF6 is absorbed chemically to the phosphate mineral surface, making it strongly attracted to water and preventing adsorption of the fatty acid. Under these conditions, the fatty acid is a selective collector for carbonate minerals, which are removed as a froth product. Next, the silicates are floated with an amine reagent added directly to the slurry without additional pulp preparation.

Jan 1, 1982

By Kenneth E. Hay

The Bureau of Mines collected coal and coal waste aggregate material from two different mine sites to determine their strength characteristics for use in concrete. The concrete would be placed underground as support walls for ground control in adverse conditions or unique mining applications. A standard mix design was established for a "wet" mix using a water-to-cement (w/c) ratio of 1.0 to facilitate pumping into place. Later, material was collected from four more mine sites and used to make 2-by 2-by 2-ft test blocks with the same w/c ratio. A pull-out cone device and borehole shear tester were used to determine the in situ material strength of the test blocks. These techniques will provide a simple and quick way of determining support wall strength in an underground environment. Test results from the pullout cone de-vice showed a good correlation of 0.98 to test cylinder compressive strengths of the same mix. Results of the borehole shear tester were inconclusive.

Jan 1, 1986

By H. Kenworthy

[Experimental studies were made to develop a laboratory technique for direct removal of cadmium and germanium from sphalerite concentrates. Cadmium- and germanium-bearing concentrates from the Illinois-Kentucky fluorspar field were sound to be, amenable to an inert atmosphere fuming process for removing these two moats in the form of gaseous sulfides. Treating the condensed fume by pyrometallurgical methods upgraded the material end provided a means of partly separating the constituents. Cadmium was concentrated about 35:1 arid germanium about 300:1. The extractive investigations were supplemented by vapor-pressure studies on the sulfides of germanium to obtain fundamental data for larger scale laboratory conditioning and control when treating the zinc concentrates. Vapor-pressure curves were developed for synthesized monosulfide and disulfide The results of these- investigations indicate the possibility of significantly increasing the recovery of cadmium from zinc concentrates. Comparison with present recovery of germanium cannot be made, since commercial recovery data arc not available.]

Jan 1, 1956

By Thomas C. Miller, Charles E. Mongan

"This publication is a progress report on Bureau of Mines studies in applying sonar techniques to roof-control problems in coal mines. Preliminary tests in the laboratory were made on layers of roof rock. To apply the experience thus obtained, a unit was designed and constructed and was used underground.The term ""sonar technique"" refers to the system of generating a beam of sound waves, shaping and directing the beam, introducing the beam into a medium to be studied, and examining any returning waves with a view of inferring the nature of the material traversed by the waves and the presence of interfaces or obstacles in the medium.The theory and actual underground experiments indicate that the sonic method is feasible. Information from physical tests made in the Bureau's Experimental mine confirmed the validity and potential usefulness of the sonar method. Lighter and more compact apparatus is desirable, and permissible equipment suitable for use in gassy or dusty mines must be developed. However, no particular difficulties are anticipated; consequently, this scientific approach to the exploration of roof strata shows definite promise. INTRODUCTIONThe problem of roof control in the coal-mining industry is of major importance. More than 50 percent of all coal-mine fatalities and 25 percent of all nonfatal serious injuries are caused by falls of roof, face, or ribs. The Bureau estimates that more than $128 million was spent by the coal-mining industry in 1958 for supporting roof."

Feb 1, 1960

By Phillip W. Holland

The U.S. Bureau of Mines has developed a mass spectrometer method for determining helium in the parts-per-million to 10% range to an accuracy of ± 1%. The method employs a mass spectrometer, an inlet system utilizing a chromatographic gas-sampling valve, and an activated coconut charcoal trap cooled with liquid nitrogen. Gravimetrically prepared standards of helium in nitrogen were used to demonstrate the linearity of the method over the concentration range of 10 ppm to 10.66% helium.

Jan 1, 2010

By E. A. Loria

High-quality sheet of electrowon molybdenum was attained by a sequence of procedure on pressed and arc-melted crystalline powders. The procedures included high-temperature, high-vacuum sintering treatments and the use of metal deoxidizers instead of carbon to improve the mechanical properties of the molybdenum sheet. Rolled sheet 60 mils thick was evaluated by tensile and bend tests, hardness measurements, microstructures, and recrystallization treatments. After stress relieving, yield strength ranged from 85,000 to 110,500 psi (0.2- percent offset) and ultimate strength ranged from 87,200 to 117,250 psi with 4.5- to 25-percent elongation observed for arc-melted sheet, and 5.0- to 23- percent elongation observed for powder metallurgy sheet. In room temperature bend tests the sheet yielded plastically, indicating that the ductile-brittle transition point was below room temperature. The diamond pyramid hardness (DPH) of the molybdenum sheet changed from 214 to 293 DPH for the stress-relieved condition to 177 to 185 DPH for the fully recrystallized condition. The brittleness of recrystallized molybdenum, reported by other investigators as characteristic of sheet prepared from commercial-grade hydrogen-reduced powders, was not in evidence. Recrystallized tensile specimens pulled at room temperature had an average elongation of 31 percent.

Jan 1, 1966

By Sidney Katell

Several systems have been proposed for the production of synthetic crude oil from oil shale. An economic analysis of one proposed system is presented in this paper. An oil shale complex to produce 100,000 barrels per calendar day of semirefined crude oil will require a capital investment of $426,216,400. This investment includes mining, retorting, intermediate pipelining, and partial refining. A selling price of $3.74 per barrel of product will be necessary to maintain a discounted cash-flow rate of 12 percent.

Jan 1, 1971

By Perry G. Cotter

As a portion of a general program for the synthesis of hard materials, a method was sought by which the hardness and density of tungsten carbide (WC)-cobalt compacts could be increased. It was demonstrated by Cotter that these improvements in quality could be made by employing an electric-resistance sintering process in which heat and pressure are applied simultaneously to presintered compacts composed of powdered tungsten carbide and cobalt. This conclusion was based on tests of material prepared by Cotter on welding equipment in use at the U. S. Naval Engineering Experiment Station, Annapolis, Md., and at Rensselaer Polytechnic Institute, Troy, N. Y. Rockwell-hardness tests made at Norris and core-drilling tests made at the Mount Weather Station of the Bureau of Mines indicated that, for some purposes, carbide material made by this process might be superior to the chemically analogous commercial products prepared by ordinary sintering methods. A program to develop optimum conditions for the electric-resistance sintering of tungsten carbide-cobalt compacts was initiated. The program was followed by a systematic evaluation of the hardness and density of compacts prepared by this method along with a series of carbide compacts furnished by various manufacturers. This paper presents a description of the electric-resistance sintering of tungsten carbide-cobalt compacts and the results of comparative physical tests.

Jan 1, 1955

By John R. Bartels

In laboratory testing, the Bureau of Mines established criteria by which common resin-grouted roof bolting systems can be evaluated and compared. Ultimate strength and stiffness were determined for nonten-sioned full-column, point-anchor, tensioned full-column, and debondable resin-grouted bolts, and for variations on full-column boltsn Bolt per-formances were compared using the performance of the 3/4-in full-column resin-grouted bolt as the standard. New and innovative systems can also be qualitatively compared against this standard. Since the medium into which a resin-grouted bolt is installed is one of the most important parameters affecting bolt performance, various host mediums were used in the testing: sandstone, concrete, simulated coal, simulated shale, and plaster. Bolt performances expected in other mediums can be inferred from the response patterns obtained in these mediums. Results indicate several functional differences among bolt types. Where resistance to shear is important, point-anchor bolts may outperform nontensioned full-column bolts at a lower cost. In medium-to soft-strength rock, tensioned full-column bolts perform best. Also, varying the resin-steel ratio seems to have little effect on the properties of a full-column bolt, when proper resin mixing is ensured.

Jan 1, 1985

By G. M. Wilemon

The Bureau of Mines conducted preliminary investigations on the use of an acid-alcohol leaching technique for recovering phosphate values from phosphate matrices. H2S04 and methanol were used as the leaching agents. Starting-matrix particle size and acid-apatite ratio were found to significantly affect the efficiency of phosphate leaching. Phosphate extractions of more than 80 pct were obtained when minus 200-mesh ore was used and the acid-apatite ratio was 8:1 or more. The iron and aluminum oxide impurities (R203) present in the crude acid products were monitored, and R203-P205 ratios are reported. Phosphate extractions in excess of 80 pct also were obtained when phosphatic clay wastes were leached. Typically, leach slurries filtered using test leaf filters ex-hibited filtration rates of 100 lb/(h·ft2) or more.

Jan 1, 1987

By N. A. Gokcen

Equilibrium partial pressures of gaseous HCl and H2O over aqueous binary and ternary solutions of HCl and AICls were calculated or estimated in the range of 20° to 110° C, and up to saturation with AlC13?6H2O. The results were extended to solutions containing less than 10 wt-pct FeCl3 by assuming that FeCl3 and AIC13 are equivalent on the molar basis, since both salts have trivalent cations with a cammon anion. The ionic activity coefficient of HCl and the equilibrium constant for dissolution of gaseous HCl were also computed. This research is part of the effort by the Bureau of Mines, U.S. Department of the Interior, to provide thermodynamic data to expand the technology base relevant to the extraction of alumina from nonbauxitic domestic raw materials.

Jan 1, 1980