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By Richard L. Fischer

Constant-volume charges of precipitated PETN (pentaeythrite tetranitrate) at three specific gravities (0.50, 1.00, and 1.50) were used in laboratory tests to examine the effects of changes in explosive properties on free-surface displacement pulses and on crater dimensions. The tests were performed in large blocks of cement-mortar. The values for the detonation velocity, detonation pressure, specific energy, energy density, and energy release rate were calculated from the explosive loading density. Calculated explosive properties were correlated with free-surface displacement pulse measurements, strain energy, and measured crater dimensions. Increases in explosive properties resulted in increased free-surface displacement pulse parameters and crater dimensions. The loading density, detonation velocity, energy density, detonation pressure, and energy release rate were found to be best indicators of explosive performance. Simple acoustic relationships involving impedance ratios were examined and could not be used to predict peak displacement amplitude or strain energy. Data are presented in the customary English units as well as the International System of Units (SI).

Jan 1, 1970

By W. R. Hardwick

This paper describes block -caving methods and practices of the Bagdad Copper Corp. in Yavapai County , Ariz . It is one of a series being prepared by the Federal Bureau of Mines on mining methods , practices , and costs in various mining districts of the United States . The story of the Bagdad caving operation is of particular interest because the ore body was not as thick as at other mines where the method had been successful . At Bagdad the caving method worked very well as a smallscale operation of 300 tons per day but was abandoned when production was increased to 2,000 tons per day . The Bagdad mine is in western Yavapai County , Ariz . , about 22 miles northwest of Hillside , a station on the Phoenix -Ash Fork branch of the Atchison , Topeka & Santa Fe Railway system ( fig . 1 ) . Copper ore now is mined by open -pit methods . The ore is concentrated , and the concentrates are trucked to Hillside and shipped by rail to a custom smelter . Some molybdenum sulfide is produced as a byproduct . This report gives a brief history of the district , describes the ore de- posit , and outlines the methods of prospecting , exploration , and estimation of ore . Development and former underground mining , including stope preparation , stoping , and transportation , are described . Extraction of ore , production rates , miscellaneous operations related to mining , wage and contract systems , and method of concentration are described . The final section discusses mining costs . The underground mine was visited by the author several times between 1937 and 1942 , and some information has been drawn from personal notes . The property again was visited in June 1957 , and maps and plans for this paper were furnished by the company at that time ; they have been edited to conform with Bureau of Mines format . The underground mine could not be visited then because it had been closed in 1948 when open -pit mining was begun .

Jan 1, 1959

By L. S. Harner

This paper which describes the milling practice at the Golden Cycle mill is one of a series of similar papers being prepared by the United States Bureau of Mines. The mill of the Golden Cycle Corporation, formerly known as the Golden Cycle Mining and Reduction Co., is located at Colorado Springs, Colorado, and has been operated since 1907. It is now and has been from its inception almost exclusively a custom mill.

Jan 1, 1933

By P. C. Good

Tungsten metal in fused form and of high purity was prepared by reducing tungstic oxide with redistilled calcium metal in a heavy-walled sealed reactor. Alloys of tungsten with vanadium, molybdenum) chromium, columbium, and tantalum were prepared by coreduction of mixed metal oxides in the same manner. This work was undertaken by the Bureau of Mines to investigate new approaches for preparing tungsten and its alloys in high-purity form. The standard method of producing tungsten metal has been the reduction of tungstic oxides by hydrogen. The resulting metal powder is compacted, sintered, and fabricated by powder metallurgy methods. Long experience in this field has resulted in the development of a technology that (by careful control of the variables such as metal composition, particle size, and sinterng technique) is well adapted to producing wire and the small shapes usually prepared from tungsten metal.

Jan 1, 1961

By H. P. Greenwald, H. C. Howarth

There was reported in Bureau of Mines Technical Paper 5754/ a series of tests to determine the compressibility and bearing strength of specimens prepared from blocks of potash salt obtained from a mine near Carlsbad , N. Mex . The events leading up to the investigation were sketched in a foreword by George S. Rice , then chief mining engineer of the Bureau ( retired September 30 , 1937 ) ; this foreword also gives a discussion of the possibility of increasing the ultimate total recovery of the potash salt by " second mining" of pillars or by use of a longwall system . In June 1936 , Rice and the senior author visited Carlsbad with H. I. Smith , chief of the mining division of the Geological Survey , to observe mining then in progress and to discuss with the management of one of the mines records of convergence of roof and floor which they were obtaining . It developed that serious thought was being given to the possibility of roof failure resulting from shear at the faces of pillars . There was envisioned the danger of such cracks extending upward to water - bearing strata . Obviously , the simple compression tests of the potash salt then being made would throw no light on this question , and tests of assemblies of potash and roof salts would have to be made . In this connection it is to be remembered that in the mine no sharp division exists between the potash salt being recovered and the nearly pure halite which forms the roof . The interlocked crystalline structure is continuous , and there is merely a very rapid decrease in the proportion of sylvite in a short distance vertically . Figure 2 of Technical Paper 575 shows that two samples near the top of the salt being mined contained , respectively , 51 and 65 percent potassium chloride . Contrasted with this is an analysis of the roof salt given on page 24 of that publication , which showed only 3.6 percent potassium chloride . As the data given in Technical Paper 575 show , the roof salt is much less plastic than the potash salt . The immediate roof may then be thought of as a more rigid stratum of indefinite extent resting on and continuous with yielding supports and loaded uniformly at the rate of 900 to 950 pounds per square inch . Just what thickness of the salt should be considered as immediate roof is uncertain .

Feb 1, 1938

By Donald F. Smith

This report describes the construction and calibration of two ice calorimeters and includes results of high-temperature heat-content measurements, made by the Federal Bureau of Mines, on rubidium fluoride, hafnium tetrafluoride, cesium chloride, and cesium iodide. The heats and entropies of fusion of rubidium fluoride, cesium chloride, and cesium iodide have been calculated at their respective melting points using equations derived from the experimental heat-content data. Hafnium tetrafluoride did not melt within the range of temperatures investigated. Heat and entropy of transition of cesium chloride from the alpha to the beta form were also determined. INTRODUCTION Free-energy data usually afford the cheapest and quickest means of determining the feasibility of experimentally untested reactions. For known reactions, free-energy data show the variation of the equilibrium constant with temperature and make it possible to calculate, without experiment, the maximum ratio of product to raw material for a given chemical process.

Jan 1, 1961

By Charles H. Fulton

One of the first matters to receive attention from the Bureau of Mines when it was authorized to undertake investigations relating to wastes in the mineral industries was the smoke problem at smelting and ore-roasting plants. This bulletin is published by the bureau primarily for persons who seek information on the subject of metallurgical smoke but are unacqllainted with the technical language of metallurgy. It is, of course, not possible to free a techniCal subject entirely from teclmicalities, but, 80 far as possible, statements are made in plain and simple English. Metallurgical smoke causes considerable friction between the metallurgical industry and agriculture in certain parts of the country. Owners of smelting plants are making every effort to devise ways and means to do away with possible damage and annoyance from smoke and are meeting with success. The problem is peculiarly difficult in this country because of the large tonnages of material that must be handled. The solution of the problem is not yet at hand and much work still remains to be done. As the mineral industry is one of the great basic industries of the country and of necessity is entitled to full consideration, it should be accorded freedom to work out the smoke problem to the benefit of all concerned. The effort is made in this paper to present the problem of metallurgical smoke as it actually exists, without bias of any kind. The writer takes this opportunity to express his indebtedness to the sources of information on which he drew, many of which are enumerated in the selected bibliography at the end of this paper. In connection with the author's use of the present tense in describing plants and methods, the reader should note that none of the references in that bibliography is of later date than 1913. Much information was obtained by personal visits and by correspondence, and thanks are hereby tendered to all persons who kindly furnished data. The writer desires to thank particularly F. G. Cottrell, chief chemist of the Bureau of Mines, for criticism and comment.

Jan 1, 1915

By J. B. Rosenbaum

This report presents new findings and consolidates previously published data to provide a single reference containing a concise and comprehensive description of the Bureau's work on electrolytic chromium. Two separate systems for electrolytic-chromium recovery were developed, one designated as the oxidized system the other as the reduced system. The electrowinning of chromium metal follows the dissolution of chromium from the ore or from ferrochrome and its separation from gangue and metallic impurities. Chromite was first solubilized by pressure digestion at slightly elevated temperatures in an oxidized acid solution using Na2Cr2O7 as an oxidizing agent. Later it was found that a sodium-free electrolyte was preferable, using return-cell anolyte containing H2SO4 and Cr03 as the oxidizing agent. Gangue materials were separated from the soluble metallics by filtration; and, after the Cr+3 had been stabilized, the metallic impurities were separated as crystalline ammonium salts by vacuum crystallization.

Jan 1, 1957

By J. M. Stuve

A novel calorimetric solution technique, recently developed at the Bureau of Mines, was tested using synthetic samples of chalcocite (CU2S) and covellite (CuS). The solution of these refractory sulfides was accomplished by oxidation with bromine in a moderately acidic, aqueous solution. The resulting values for the standard enthalpies of formation (?Hf°, 298.15) for CU2S(c) and CuS(c) were -18.1 ±1.1 kcal/mol and -13.3 ±1.1 kcal/mol, respectively. These values are in good agreement with published formation values derived from other methods of physicochemical measurement.

Jan 1, 1982

By ALICE V. Petar

Through the courtesy of the State Department, the Bureau of Mines has received a compreensive report on the jede industry of Burma, pre- pared by American Consul Winfield H. Scott, Rangoon, Burza. This mater- ial is the main basis for the present circular, although free use also has been made of reports on the jede industry in China and Germany by consular officers in those countries, to whom footnote credit is given. The word "jade" is said to be derived from the Spanish "piedra de ijada" (hijada) meaning, literally, "stone of the side," as jade was supposed to cure pains in the side; nephrite (a jade mineral) was named from the Greek word meaning kidney, because it was formerly warn as a re- medy for kidney diseases. To the Burmeso, jade is known as "Kyauksein," or green stone, and to the Chinese, all varieties of the material are referred to as "Yu" or "Yu-chi", According to Confucius, jade was symbolical of. justice, harmony, intelligence, and humanity, and the Chinese of today believe that by using ornaments made of this stone, the wearer is. protected from the "evil eye" as well as from diser.se. Ornaments of carved jade were known to the ancient civilizations of Mexico and Peru and to the peoples of other sections. of Central and South America, Jade ornaments also have been found in the lake dwellings of Switzerland and in Crete; thile in China, as far back as the Chou dynasty (B. C. 1122 B. C. 255) it was used in the production of various classes of precious vessels and as insignia of rank.

Jan 1, 1936

By John H. Hild

"INTRODUCTION Alunite occurs within a radius of 10 miles of Marysvale, Piute County, Utah, in veins and as replacements of igneous rocks. A number of each type of deposit was explored by the Bureau of Mines, in cooperation with the Geological Survey, under the Strategic Minerals program during 1942. The exploratory work comprised geologic and topographic mapping, diamond drilling,,bulldozer and hand trenching, sinking test pits, rehabilitation of old workings, sampling alunite exposures, and constructing and repairing roads.ACKNOWLEDGNENTSIn its program of exploration of mineral deposits; the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches-are under the supervision of Dr. R. S. Dean, assistant director.With particular reference to this publication, acknowledgment is given to Richard E. Mieritz and William E. Young, who assisted on the project at various times; P. T. Allsman, chief. Salt Lake Division, Mining Branch, who advised on exploratory problems and gave valuable assistance in preparing the report and illustrations; A. P. T. Schumann, for preparing the illustrations; and to Gordon L. Bell, Max Willard, and Eugene Callaghan, of the Geological Survey, who cooperated as representatives of that agency."

Nov 1, 1946

By William W. Adams

Not since complete records of accidents first became available has the safety record of the quarrying and related industries of the United States been as favorable as it was in 1940. The combined accident-frequency rate was lower and therefore better than in any year since 1916, the first year for which complete and comparable figures are available. Although operating companies began to furnish accident reports to the Bureau of Mines in 1911, the reports for that year and the next few years were obviously incomplete as to number of accidents reported, especially slight injuries involving only 1 or 2 days of disability of the injured employees. By 1916 the reports from operating companies appeared to be reliable as to completeness of coverage of slight injuries. Although the number of men employed in 1940 was by no means a record, it represented a gain over each of the 2 preceding years. Likewise, the number of man-hours worked during 1940 was larger than in 1938 and 1939.

Jan 1, 1942

By Harold J. Bennett

The purpose of this study was to develop methods for the financial evaluation of mineral deposits. This includes the selection of the best alternative mining and processing methods and production rates. This was done by performing a financial evaluation through computer simulation using sensitivity and probabilistic risk analysis. The criterion used to measure the relative advantages of these investment and operating alternatives is the discounted-cash-flow rate of return. Included is a description of the theory and methods used in the probabilistic analysis approach, which is based on the premise that the expression of a range of values in establishing an estimate for a parameter is more realistic than the choice of a single value. Numerous simulations are made using randomly selected values of the input parameters resulting in a frequency distribution of the rates of return and their relative probability of occurrence. The sensitivity analysis method is described and combined with the probabilistic analysis to interrelate mineral reserves, capital investments, operating costs, and production rates. The ability to vary these input parameters on successive runs has permitted the selection of the best alternative mining and processing methods and production rates for a given mineral deposit. For illustrative purposes the evaluation of a mineral deposit was performed using three alternative mining and processing methods at three different quantities of resources and various production rates and prices. The computer program used in this analysis was written in FORTRAN II for maximum compatability and should run without modification on most computers having BK (8,000-word) core memory, a card reader, and printer (120 characters per line).

Jan 1, 1970

By Floyd R. Anderson

Noise control of existing pneumatic drills is difficult and runs into cost, performance and weight penalties. A need exists for a start-from-scratch approach for quiet pneumatic rock drills. The designs based on Leavell Principles which has been successfully used in demonstrating a quiet and vibration free paving breaker, is the concept chosen here. This report shows the feasibility of a quiet stoper for drilling roof bolt holes in coal mines. The work is directly applicable to pneumatic percussive rock drills. The report shows an oscillator based on patented Leavell concepts which results in a vibration free tool and noiseless exhaust. Dynamics of the oscilator is analyzed. Independant rotation of drill rod is provided by an air motor (screw expander) and flushing of cuttings is accomplished by an air ejector in a compact lower housing. The feasibility of no exhaust noise, low drill machine noise, and vibration free casing is discussed.

Jan 1, 1977

By Arno C. Fieldner

Six years ago, I addressed the annual meeting of the American Society for Testing Materials on "Fuels of Today and Tomorrow."3/ Since then, our country has been drawn into another great war of veritably global extent, with unprecedented demands on fuels, foods, and materials in general. My purpose in this address is to review the changes in fuel supply and demand since 1937 and to give you my views on the outlook for the future. CONDITIONS IN. 1237 Daring 1936 the United States produced and consumed one-third of the world production of coal, two-thirds of the petroleum, and about 95 percent of the natural gas. Two-thirds of the oil produced in all countries since the discovery well was drilled in 1859 had come from American wells. With the exception of the three depression years 1931, 1932, and 1933, new oil reserves were being discovered since 1924 well in excess of our increasing rate of consumption. Discoveries of natural gas, likewise, were tremendous in volume, and this fuel was being transported to most parts of the country by pipe lines; some of them more than 1,000 miles long. We had all kinds of mineral fuels in abundance and at prices that did not stint anyone in the maximum utilization of the mechanical devices that were being developed on every hand. No one suspected that the time might come in a few years when, gasoline would be doled out to some of us at the rate of 1-1/2 gallons a week or that many of our fuel-oil furnaces would have to be converted to burn coal. Of course, these restrictions are due to unusual war conditions, such as lack of coastwise tanker transportation, unprecedented demand for aviation gasoline, and the shortage of rubber for automotive tires. However, these shortages do call our attention to the vital part of petroleum reserves in our country's future position among nations. Therefore, it is of special interest to review briefly the relations of recent supply and demand with respect to our various mineral fuels.

Jan 1, 1943

By C. F. Ellis

Interest in the composition of automobile exhaust gases has been greatly accelerated by recent studies that have indicated that these gases contribute to smog formation in urban areas. Several analytical methods have been published for the analysis of the hydrocarbons in the exhaust gases, but similar information has not been published on the analysis of the oxygenated compounds. This report presents procedures for chemical analyses of certain oxygenated compounds, procedures for sampling the exhaust gases for these analyses, and the analytical results of some experimental work in which these procedures were used. A stationary 1956 model, 170 horsepower, V-8, dynamometer-mounted engine, operated to simulate vehicular cruise conditions, was used for the study. Exhaust gases produced from a regular-grade Midcontinent gasoline during 15-40- , and 60-mile-per-hour cruise operations were analyzed by chemical methods for formaldehyde, total aldehydes, total carbonyls, total alcohols, carbon associated with the oxygenated compounds, and the oxides of nitrogen. Experimental results indicate: 1. The range of concentrations of the total of the functional groups of oxygenated compounds, expressed as moles per million moles of water-free exhaust gases, is about 90-100; the concentrations increase with engine speed. 2. Aldehydes comprise about 80-90 mole- percent of the total of the oxygenated groups, and formaldehyde accounts for about 50 mole-percent of the total aldehydes. 3. The order of magnitude of the concentration of the carbonyls is the same as that for the aldehydes, indicating that ketones are not a major group. A colorimetric test indicates that methyl ketones Constitute about 2 mole-percent of the oxygenated compounds.

Jan 1, 1961

By F. J. Palumbo

An electronic color-sorting machine was tested for recovering colorless glass concentrates from mixed glass products. The tests were made using glass recovered from unincinerated (raw) urban refuse and residues resulting from the incineration of refuse. The results of the study revealed that concentrates analyzing about 86 percent colorless glass could be recovered from mixed unincinerated glass containing 54 percent colorless glass material. Recovery of the colorless glass was about 62 percent. Color sorting the incinerated glass was somewhat more difficult. Multiple-stage processing was required to recover 59 percent of the colorless glass material in a product analyzing 89 percent colorless glass. The feed material analyzed 41 percent colorless glass.

Jan 1, 1971

"INTRODUCTION These safety standards for anthracite mines have been prepared for use as a guide for Federal inspectors. They are a revision of ""Tentative Inspection Standards for Anthracite Mines,"" published as Bureau of Mines Information Circular 7282 issued in May 1944 and used as a guide in Federal inspections. No provision made in these safety standards should be construed or operate to nullify any existing State statutes; they are intended to supplement the State statutes in the interest of increased mine safety. Mines are inspected in accordance with the Federal Coal-Mine Inspection and Investigation Act of 1941, Public Law 49, 77th Congress, H. R. 2082. Any unusual hazard noted by an inspector and not covered by these standards will be discussed in the inspection report, and suitable remedial procedure will be recommended.ARTICLE I. - SURFACE STRUCTURESSection 1. Breaker and cleaning plant.Electric switches and controls in breakers and cleaning plants should be enclosed.Where coal is dumped at or near air-intake openings, reasonable provisions should be made to prevent the dust from entering the mine.Section 2. Lamp houseNaphtha or other flammable liquids in lamp houses should be kept in approved containers or other suitable dispensers.Flame safety lamps should be permissible and maintained in permissible condition.Flame safety lamps should be properly cleaned, examined, and assembled by a qualified lamp attendant or other competent person before each period of use. Lamp assembly should again be checked by the person using it immediately before he enters the mine.When not in service, methane indicators, flame safety lamps, and electric cap lamps should be in the custody of competent persons responsible for maintenance and testing."

Feb 1, 1948

By E. C. Lane

This paper is the first putt of a report giving the results of the Bureau of Mines' twenty-third semiannual survey of motor gasoline marketed in the United States. A companion report, Part II, is in preparation and will give a more detailed discussion of the whole survey. Results of the determination of copper-strip corrosion, color, sulphur content, copper-dish evaporation residue, and gum content as given by the Bureau of Mines steam-oven method will be presented in the second paper, which will also include the prevailing retail price and the tax at the time the sample was taken. This paper deals specifically with data relative to gravity, Reid vapor pressure,' and distillation (method 100.13).6 The samples tested were divided into "competitive-price gasolines" and "premium-price motor fuels," a method of presentation that was begun with the twenty-second semiannual survey. A total of 312 samples were collected from service station pumps in 20 cities throughout the United States. Of this number of samples, 207 were "com-petitive-price gasolines" and 106 were "premium-price motor fuels." All of the samples were collected in March, 1931, and analyzed at the Petroleum Experiment Station of the United States Bureau of Mines at Bartlesville, Okla. "Competitive-price gasoline" includes those fuels that are sold at the generally recognized local base price and all fuels that are sold below that price. All fuels that are sold at an advance over the generally recognized base price are placed in the class of "premium-price motor fuels." These fuels include Ethyl gasolines, benzol blends, "high-test" fuels, and those fuels that owe their "anti-knock" rating to the process of manufacture rather than to the addition of other material such as Ethyl fluid or benzol. The term "high-test" is generally applied to motor fuels that are more volatile than the regular competitive-price gasolines. "High-test" fuels may also have a high anti-knock rating.

Jan 1, 1931

By W. W. Staley

This paper discusses the design of small head frames that will fill the needs of prospectors and small operators whose operations are conducted through shafts. The head frames considered were designed to handle relatively small tonnages. It was assumed that the shafts in which buckets are used would not exceed 300 feet in depth and that not over 60 tons of rock would be hoisted, in, 14 hours. In the design of the larger head frames, a hoisting capacity of about 250 tons per 6 hours from a depth of 300 to 500 feet was assumed. Under these conditions, hoisting speed, rate of acceleration, and weight of rope have a negligible effect on the head frame design and, therefore, have been ignored in the following, discussion. Because timber is relatively cheap and easily obtained in most mining areas, the discussion has been confined to timber construction.

Jan 1, 1937