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By BUREAU OF MINES

A complete list of permissible mining equipment, rescue apparatus and gas masks tested prior to July 1, 1928, was published in Bureau of Mines Information Circular 60772. The present list includes practically all equipment tested and, approved by the Bureau, up to and including Jan. 1, 1929. It covers electric air compressors, coal drills, mining machines, loading machines, conveyors, mine pumps, room hoists, mine telephones, rock-dusting machines, switches, electric cap lamps, flame safety lamps, electric hand and trip lamps, flash lamps, methane indicators and detectors, blasting units, storage barrery locomotives, tandem locomotives, power trucks, concrete mixers, self-contained oxygen breathing apparatus and gas masks. The system under which those devices were tested permits the manufacturer, after his equipment has passed certain tests prescribed by the Bureau of Mines, to mark his equipment with a seal shoring that it has been "approved" by the Bureau. These tests are designed to insure that the equipment has the minimum requirements for safety in use. The only object of the Bureau in making such tests and pub- lishing lists of permissible equirment is to safeguard the lives of workers and to help lesson the hazards of mining.

Jan 1, 1929

By D. L. Paulson

The Bureau of Mines used 50-and 800-kva electric-arc furnaces to confirm the feasibility of producing ferronickel in electric-arc furnaces from pre-reduced concentrate from the Yugoslavian FENI project. The relationships were established among metallic iron concentrations (degrees of prereduction), ferronickel grades, and nickel recoveries. Smelting the concentrate containing 1.27 wt-pct nickel and metallic iron levels between 2 and 3 wt-pct, produced 15 to 20 pct ferronickel. Higher or lower metallic iron concentrations were compensated by adding oxide pellets or carbon to the electric-arc furnace charge. Over 90 pct of the contained nickel was recovered when up to 20 pct ferronickel was being produced. Data obtained while smelting 16 tons of prereduced concentrate in the 800-kva electric-arc furnace indicated ferronickel can be recovered at an energy consumption of 530 kwhr/ton of prereduced material.

Jan 1, 1977

By P. L. Sibrell

Electrorefining of Ti in nonaqueous solvents has been studied by the U.S. Bureau of mines as a method for recycling impure scrap Ti. Electrochemical behavior of Ti species was investigated using cyclic voltammetry. Research results showed that Ti metal can be dissolved in polar solvents such as dimethylformamide or dimethyl sulfoxide. However, deposition of Ti from these solvents was not successful. Several solvent systems were investigated for electrodeposition of Ti but no deposits were obtained. Reduction of Ti4+ complexes to Ti3+ proved to be straightforward, but reduction to lower oxidation states could not be confirmed. In dimethylformamide solutions, cyclic voltammetry results demonstrated the reduction of Ti to an oxidation state of less than three, but no Ti metal was identified. In dimethyl sulfoxide solutions containing LiCl, it was possible to deposit Li metal. After adding Ti salts to the solution, electrolysis quickly passivated the electrode. Deposition of Ti was also investigated in solutions of dimethoxyethane and propylene carbonate but, again, no reduction of Ti to oxidation states of less than three occurred. Therefore, the prospects for a nonaqueous electrorefining system for Ti metal do not appear promising.

Jan 1, 2010

By E. G. King

THIRD-LAW entropy data for zirconium-containing compounds are sparse. Kelley a lists entropies at 298° K. for the oxide, tetrachloride, nitride, and silicate, as well as for the metal. The present paper presents heat capacities between 51° and 298° K. and entropies at 298.15° K. for the zirconates of the alkaline-earth metals-calcium, strontium, and barium. The authors believe magnesium zirconate does not exist as a stable compound at room temperature. Entropies of formation from the constituent oxides also are given. MATERIALS The materials used in this investigation were synthesized and analyzed in the Berkeley Laboratory of the Bureau of Mines. Calcium zirconate was prepared by heating an intimate mixture of reagent-grade calcium carbonate and pure zirconia for 30 hours between 1,200° and 1,300° C. and for 32 hours between 1,400° and 1,500° C. As part of the heating schedule, the sample was ground and mixed seven times. Periodic analyses and minor adjustments of composition were made. Analysis of the final product gave 31.19 percent calcium oxide (theoretically 31.28 percent) and 68.67 percent zirconia (theoretically 68.72 percent). The X-ray diffraction pattern agreed with that in the ASTM catalog.

Jan 1, 1960

By L. E. Green

For shortwall mining to be profitable, the additional capital investment of about $1 million for shortwall roof supports must be offset by decreased total operating costs and/or increased coal production. The Bureau of Mines therefore conducted a demonstration project to compare shortwall and room-and-pillar mining. Daily two-shift production from the bureau of Mines-Beth-Elkhorn Corp. shortwall demonstration n project averaged 975 tons of raw coal, compared with 905 tons from a room-and-pillar unit operating undo r similar conditions. The estimated direct operating costs for the shortwall and room-and-pillar unite were $4.21 and $4.03 pier ton, respectively. The profitability of the shortwall system was found to depend not only on the increased depreciation cost of the powered roof supports and the decreased cost of supplies and materials but also on such factors as the fixed and variable indirect costs and the selling price of the coal. Shortwall mining was demonstrated to be a viable alternative to room-and-pillar mining.

Jan 1, 1977

By H. P. LeVan

Research was conducted to examine the feasibility of extracting manganese from Georgia umber ore by a three-stage continuous sulfuric acid-ferrous sulfate pickle liquor leaching process. A continuous cyclic process for treating the umber was operated successfully, using a synthetic solution simulating a ferrous sulfate fortified anolyte solution discharged from a manganese electrolytic cell as the leaching medium. Leaching efficiency based on removal of the manganese from the ore ranged from 83 to 89 percent for all systems tested.

Jan 1, 1965

By Robert E. Barieau

This report describes a method for treating pressure-volume-temperature (PVT) data obtained with a Burnett compressibility apparatus. The method makes use of a general nonlinear least-squares technique developed at the Bureau of Mines Helium Research Center. It is assumed that an adequate functional form is available for the expression of the compressibility factor as a function of either the molal density or the pressure. The functional form of the compressibility factor can be either linear or nonlinear in the parameters to be evaluated. Formulas are given for calculating variances and covariances of all parameters evaluated and for calculating the variance of calculated quantities of interest.

Jan 1, 1967

By R. V. Higgins

The, large volumes of low A. P. I. gravity oil that will remain in many shallow fields of California when such oils no longer can be recovered profitably by pumping are important potential sources of oil when ways and means are found to remove them from the reservoir sands. Estimated ultimate oil recoveries in many of the "low-gravity fields" of the San Joaquin Valley in California indicate that less than 25 percent (on the average) of the original oil will be recovered. These oils have viscosities of 1,000 or more centipoises at reservoir temperatures and, because of their high viscosity and low intensity of the reservoir pressure, the quantities that will be retained in the sands ultimately are so large and their recovery is such a challenge to petroleum engineers that the Bureau of Mines has made the study of their possible recovery one of its major projects. The fact that a slight increase of temperature materially reduces the viscosity of low A. P. I. gravity oils has 'prompted the use of various means for increasing the temperature of the oil in the reservoir sands and hence the rate of flow and Completeness of recovery of the oil. Hot oil, hot water, heated air, and natural gas, steam, super-heated steam, and the products of combustion have been circulated in wells to raise the temperature of the oil it the sands; electric heaters have been installed in wells, and butane and air have been intermittently exploded and the flames propagated through the tubing to the "pay" zones. None of the methods, however, have been entirely satisfactory for the recovery of large quantities of oil.

Jan 1, 1949

By A. C. Fieldner

In preparing this paper, an attempt was made to obtain results of plant-scale carbonization tests on washed and unwashed coal from the same mine. A letter. in which the following questions were asked was sent to some 50 coke-oven superintendents and others who might be interested; "What is the influence of washing coal on: (1) The chemical and physical properties of coke, as for example, the size the amount of breeze, the fracture, strength, cell-structure, etc. (2) The quantity and quality of gas and by-products. (3) The capacity of the ovens. (4) The composition of the coal. "Your general opinion, as well as any specific data or results of tests, on this important subject will be arc greatly appreciated."

Jan 1, 1930

By P. L. Woolf

Seven evaluation tests with blast furnace iron bearing burden materials are described. The effects of pellet strength, fines in the burden, decreasing slag volume, pellet size, eliminating stone with superfluxed sinter, and eliminating stone by prefluxing the pellets were determined. Fluxed pellets and fluxed sinter made with the same ore fines were compared. The tests were conducted under cooperative agreements between the Bureau of Mines and North American steel companies. The objectives were to improve blast furnace practice, expand and develop understanding of the operation and theory, quantify the effects of changes, and explore the limitations of operability. This work was part of an extensive program of blast furnace research in experimental blast furnaces at Bruceton, PA conducted in the years 1958 to 1967.

Jan 1, 1984

By N. F. LeJeune

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Jan 1, 1924

By A. W. Deurbrouck

Four samples of Pittsburgh-bed coal, of various size consist and ash content were dewatered in a pilot-size vacuum-disk filter partially enclosed with a steam jacket. Steam fed at 2.5 to 12.5 pounds per minute reduced the moisture content of the filter cakes from 2.8 to 13.8 percentage points more than normal vacuum dewatering. Approximately 1.5 pounds of steam was required to remove 1 pound of water.

Jan 1, 1966

By B. K. Shibler, I. S. Solet, H. W. St. Clair

"This study was undertaken to provide a more adequate knowledge of the chemistry of the sulfide volatilization process for recovery of tin from low-grade Bolivian ores. The investigation was partly supported by the Department of State under its program for scientific cooperation with South American republics.The results of this investigation demonstrate the conditions under which cassiterite (Sn02) may be converted to stannous sulfide by reaction with pyrite or sulfur vapor. Quantitative data are given on the rate of sulfidization and on the vapor pressure of stannous sulfide.INTRODUCTIONAlthough the United States is the world's largest consumer of tin, virtually no tin ores occur within our national borders. Most of the world's tin supply comes from alluvial deposits in the Far East and in Africa, The major sources of tin ores are Malaya, Indochina, Bolivia, Belgian Congo, Nigeria, Thailand, Burma, China, and the United Kingdom. Bolivia is the only important source of tin in the western hemisphere. It was the chief source of tin f or the United States during World War II. The Government-owned tin smelter at Texas City, Tex., was built primarily for smelting Bolivian ores and depends largely on Bolivian ores for its operation. Bolivia is the only major tin-producing country in which the tin ores occur as vein or lode deposits requiring underground mining. Most of the tin from the Far East and Africa is mined by dredges from alluvial or placer depos its. It is recovered as a high-grade concentrate of cassiterite relatively free from impurities. The tin minerals in the lode deposits are more intimately associated with other minerals and more difficult to separate into a clean concentrate. Furthermore, a large part of the tin in the original ore is lost during concentration. The ores as mined contain only a few percent of tin, so they must be milled to separate the gangue minerals and produce a concentrate containing 30 to 40 percent tin before they are shipped to the smelter. The losses of tin that occur during milling vary from 18 to 65 percent. The average recovery of tin from Bolivian ores is probably 50 to 60 percent."

Dec 1, 1954

By G. E. McElroy

"while investigating the presence of heavy strata gases* in certain mines of the East Tintic mining district of Utah, a small, local body of light, very hot gas of high-nitrogen composition was noted in one of the mines. Observations and analyses indicate that this light gas was resulting from very rapid oxidation of finely disseminated pyrite, in lead-silver sulphide ore. The gas was actually mine air which had lost a large proportion of its oxygen content by reaction with the pyrite. This body of gas was hanging in a local high spot about 5 by 5 by 5 feet in size, caused by caving, at the end of a crosscut. Fifty feet from this spot, an air current of 6000 cubic feet per minute was entering the 5 by 7 foot cross-cat from a raise from below.On account of the vapor contained in the gas, the bottom level of the gas could be plainly seen and was practically a horizontal plane, but of slightly wavy appearance, coinciding with the point where an acetylene light was extinguished. This body of gas was visited on three occasions and samples obtained by means of evacaated bulbs and by water displacement. The temperature of the gas was ap¬proximately 175 degrees P. on all three occasions, so that sampling required thick gloves and quick action. Air three feet below the vapor line had a temperature of only 120 degrees F., and a relative humidity of 27 per cent. The stratification of the air and gas mixtures was so sharply defined that the sampler could hold his head a few inches below the vapor level for an appreciable period of time without any noticeable effect other than that due to the high temperature. At one foot below vapor level, it was 135 degrees F., and the relative humidity was 30 per cent. When a candle and an acetylene light were raised into the gas from below, the candle flame was extinguished at a point two inches lower than the acetylene flume, indicating a drop in oxygen content from about 16 per cent to 12 per cent (oxygen content of normal dry air 20.05 per cent) in the distance of two inches."

Sep 1, 1921

"MASSACHUSE'M'S INSTITUTE OF TECHNOLOGYBOLSAITIS, PETERMassachusetts Institute of TechnologyDepartment of Mineral Engineering77 Massachusetts AvenueCambr1dge,MA 02130(614) 253-5069ELLIOIT, JOHN F.Massachusetts Institute of TechnologyDepartment of Mineral Engineering77 Massachusetts AvenueCambridge, MA 02130(617) 253-3305RING, TERRYDepartment of Materials Science and EngineeringMassachu5etts Institute of TechnologyCambridge, MA 02130(6117) 253-4299"

Jan 1, 1988

By R. V. Ramani, C. B. Manula, A. Owili-Eger

PART 1 THE INPUT AND OUTPUT DATA AND THE MINE SCHEMATIC SHOWING THE FLOWS FROM COMPUTER SOLUTIONS FOR APPLICATION I

Jan 1, 1975

By Katherine Harding

Basic concepts of matrix algebra and manipulations of matrices are presented in such a way that little competence in mathematics is required. Examples are always included to illustrate concepts and techniques. The paper is divided into six sections. The first four sections are devoted to some of the more basic concepts of matrix algebra, whereas the last two sections are concerned with specific applications.

Jan 1, 1967

By Jeran Paul W., Michael A. Trevits

Subsidence data gathered by the U.S. Bureau of Mines over a series of longwall panels in the Pittsburgh Coalbed were studied to obtain insight as to the role of time in the subsidence process. It was found that subsidence began essentially with undermining and was completed within 1 year. The progress of the subsidence was dependent upon location above the panel. Subsidence in the central area of the subsidence trough, where subsidence is the greatest, was about 90 pct complete by the time the face had progressed a distance equal to one overburden thickness beyond a particular surface point. For a point over the rib of the longwall panel, the subsidence was only about 60 pct complete at this time. Data from three other sites in the northern Appalachian Coal Basin were analyzed to determine if an anomaly or the true characteristics of the subsidence process had been observed. All sites behaved similarly in the central portion of the subsidence trough. However, the subsidence of points over and adjacent to the ribs of the longwall panels was site specific. The fact that movement across the width of the panel was not uniform should be taken into account in assessing damages or the potential for damages resulting from mining-induced subsidence.

Jan 1, 1995

By F. S. Wartman

Recent changes in metallurgical practice, particularly those in flotation, have altered greatly the functions of the different units of a copper smelter. Gangue minerals are removed from the feed so much more thoroughly that the reverberatory furnace, once virtually a concentrator in which a low-grade ore was concentrated into a rich matte by virtue of the removal of gangue elements as slag, has become very largely a melting furnace in which the rich flotation concentrates are rendered molten so that they may be converted. Moreover, since the proportion of matte to slag in the reverberatory furnace output is greater than it was formerly, the amount of converter slag returned to the reverberatory for cleaning is, in comparison to the amount of slag actually formed in that furnace, also much larger. In some cases, approximately half of the reverberatory dump slag may have originated in the converter. The increase in the proportion of convertor slag to total slag produced has brought about certain consequences not entirely desirable. Converter slags contain a high percentage of iron and therefore are high in specific gravity and are very basic. A considerable guantity of magnetite, both dissolved and suspended as solid crystals, is always a component, The basic nature of the ordinary converter slag and the presence of the suspended magnetite crystals make impossible the reduction of the copper content of the slag below approximately 1 per cent by even the most prelonged settling, and a re-treating process is necessary. At present, general practice in western copper smelters is to return the converter slag molten to the reverberatory furnace. Here dilution by mixing, with slag formed in the reverberatory furnace and reaction with raw sulphides and siliceous materials in the reverberatory feed reduce the magnetite and increase the silicates to the point necessary for a satisfactory dump slag.

Jan 1, 1930

By A. Wahab Khair

"Geologic materials emit transient noises when stressed /1/. The rate and pattern of these transient noises or acoustic emissions (A.E. hereafter) depend on the stages of deformation of the material /2/. It has been demonstrated that rock/coal fracture processes under stress consist of three distinctive stages--crack initiation, propagation and ultimate fracture--and that coalescence of numerous cracks leads to ultimate failure rather than the propagation of a single crack /2,3/. This paper presents an analysis of fracture formation in rock/coal specimens subjected to straight wedge indentors using A.E. technique.The effect of specimen geometry, wedge indentor angle, confining pressure, and material anisotropy on fracture type (tension, extension, and shear crack), fracture length, and fracture intensity were studied. Two types of material mainly Berea sandstone and Coal Berg No. 2 coal were used in this study. Prior to the experiment the mechanical properties of both sandstone and coal were determined using rectangular specimen (Figures 1 a) in standard compression tests and are given in Table 1. In this study cylindrical and rectangular specimens were first prepared to proper dimensions of 2 in. x 1.5 in. and 3 in. x 1.5 in. x 1.5 in. (5.08 cm x 3.81 cm and 7.62 cm x 3.81 cm x 3.81 cm), respectively and then instrumented with SR-4 strain gages as shown in Figure 1. The instrumented specimens were then tested under four distinct load boundary conditions as illustrated in Figure 2. During a typical experiment the instrumented specimen was placed in a specially designed loading jig (Figure 3) where a predetermined lateral pressure was applied mechanically to the specimen by adjusting the inner plate of the confining chamber via screw while monitoring strains in the specimen. Using rock/coal elastic constants and measured strains, a predeter¬mined lateral pressure was applied to the specimen. Then a vertical load was applied by the straight edge of a wedge indentor attached to the upper platen of the universal loading machine via ball and socket arrangement (Figure 4). The arrangement allowed uniform application of load in a straight line manner on the surface of the specimen. During the test a number of parameters namely strains, load and A.E. rates were recorded (Figures 5a-b)."

Jun 1, 1988