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By P. G. Clites

This study was undertaken to determine the effect of consumable-electrode vacuum arc melting on the properties of copper and to determine the applicability of the process to the production of cast shapes of copper. Ingots and castings were produced from electrolytic tough pitch copper (ASTM designation ETP), from electrolytic cathode copper (ASTM designation CATH), and from oxygen-free copper (ASTM designation OF). The products of this study were evaluated to determine the effect of the melting process on the removal of impurities from the copper and on the physical properties of the copper. The results indicate that consumable-electrode arc melting can be satisfactorily applied to the melting and casting of copper. Ingots prepared directly from electrolytic cathode copper contained slightly higher levels of impurities than are found in commercial oxygen-free copper, Excellent results were obtained with centrifugal castings of unalloyed copper, and reasonably successful static castings can be produced if proper mold and gating systems are employed.

Jan 1, 1963

By G. W. Grove, O. V. SIMPSON

During the years 1945, 1946 , 1947 , and up to July 1, 1948, only one death was caused by mine fires in bituminous - coal mines of the United States . The one fatality occurred in an Illinois mine in December 1945, and , therefore, there had been a period of 2-1/2 years in which no deaths occurred as the result of mine fires . Moreover, 1946 was the first year since 1930 in which no deaths occurred from mine fires . This record is markedly better than that of 1944 , when 89 fatalities and great property damage were caused by mine fires in bituminous - coal mines and 16 additional men were killed by an explosion that occurred while they were attempting to seal a mine fire .

Apr 1, 1949

By F. S. Crawford

Although it may be impracticable to adopt standard methods of safe working in all branches of mining, and although it may be impossible to establish a standard for each class of work at each mine, some of the iron-mining companies in the Lake Superior district have found that by adopting certain standard ways of performing certain of their operations they insure both more efficient and safer working conditions. Many companies have adopted the idea that the safe way of doing things is also the most efficient and economical way, and, through the medium of their safety conferences they are trying to find the safest way, and the most efficient way, of performing practically every operation about the mines. This activity will, undoubtedly, be continued at every operation which uses this method of doing safety work, because in the advance of industry changes must be made in the results required from time to time. A review of the safety standards and safety suggestions which have been arrived at by some of the companies in this the greatest iron-mining district in the world, will be of value to companies who are interested in improving the safety of their working conditions. So that attention may be directed to the methods in use, rather than to individual companies, all names have been omitted and companies are referred to only by letter.

Aug 1, 1931

By E. D. Gardner

"The Bureau of Mines has studied blasting practices in metal mines of the Southwest. The investigation of blasting drift rounds showed among other results, that cut-holes in ground difficult to break could be chambered to advantage under some conditions.In open--cut mines, chambering nearly all holes before blasting is the common practice. Two or more free faces are generally maintained in this type of work, and the amount of explosive necessary to break any bench or bank can usually be estimated from the yardage to be moved. However, in blasting drift or tunnel rounds only one free face is available before the cut-holes are shot, and the quantity of explosive required is generally ascertained best by trial.In addition to being the most difficult to break, the cut-holes are the most important of a drift round. When the cut-holes ""break bottom"" less work is required of the other holes, and a full break of the round is generally obtained. In ground difficult to blast, extra care and expense are justified to insure that the cut-holes ""break bottom.""At many mines the work is so organized that all blasting is done at the end of the shift, and a decided advantage would have to be gained to make chambering of the cut-holes economical. Also, in many mines blasting during the shift would not be practical. One or two holes could probably be drilled during the time necessary to do the chambering. However, under certain special conditions, such as in small operations or those where ""leasers"" or contractors are working, drill holes could be chambered should there be an advantage in doing so. Moreover, in some mines it might be practical to chamber the cut-holes at the lunch hour. In ordinary rounds the cut-holes are generally drilled by noon. It would not be necessary to tear down the drill or remove tools from the face to do this work of chambering."

Feb 1, 1928

By James A. Browning

Following an unsuccessful attempt earlier in the program to develop and market a drill channelling machine, we have designed and tested a new continuous channelling method which reduces operating sound levels to below 100 db. This new method relies on a small diameter oxygen-enriched burner to produce narrow channels. Sound intensities are reduced substantially compared to conventional channel widths. They are further reduced by a water spray directed immediately above the flame. Baffles placed along the top of the channel will reduce sound levels to below 90 db. Cutting rates are greater than those of existing channelling burners with costs per unit of channel area substantially reduced for those cases where oxygen costs are reasonable.

Jan 1, 1981

By George M. Lucich

This report describes a sensitive, proportional temperature controller developed by the Bureau of Mines that is useful in the temperature range from 40 to 400° C with an accuracy of ±0.10 C. A temperature controller of this kind is potentially useful for regulating temperatures in air chambers, liquid baths, furnaces, and reaction vessels, and for other applications. This instrument was developed to control the duration and temperature of the heating cycle of a charcoal-filled adsorber that is part of a special helium analyzer used by the Bureau. The controller was made from commercially available parts, and can be easily modified to provide continuous temperature control. The circuit is solid state and employs no electromechanical devices. Over a 2-year period of use as a component of the special helium analyzer, this temperature controller performed successfully and required no maintenance.

Jan 1, 1979

By R. C. Ellman

Significant effects of in-the-mill drying on the pulverization of lignite have been demonstrated in an experimental impact-type pulverizer by tests in which the primary variable was temperature of the sweeping gas. Reduced power requirements and increased product fineness were observed as the extent of drying was increased. Pulverization with in-the-mill drying was studied in comparative tests made on lignites from five mine sources. All of the lignites responded in a similar manner; however, differences in the pulverizing characteristics of the individual lignites were significant. For one lignite, the electrical input to the pulverizer driving motor with minimum sweeping-gas temperature was 33.9 kw.-hr. per ton, decreasing to 14.0 kw.-hr. per ton with a sweeping-gas temperature of 658° F.; for another lignite, at comparable operating conditions, the electrical input decreased from 59.1 to 19.0 kw.-hr. per ton. In the first case, the product fineness increased with increasing temperature of sweeping gas from 65.2 to 79.2 percent through a 200-mesh sieve, and in the second case, from b2.7 to 86.9 percent through a 200-mesh sieve.

Jan 1, 1962

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 G. M. Martinez

A cell concept adaptable to large-scale electrowinning of zirconium metal from zirconium tetrachloride was investigated by the Federal Bureau of Mines. Tests were made in twin cells, each 12 inches in diameter by 33 inches long. Electrowinning was performed in one chamber from which the electrolyte was transferred after electrolysis to the other chamber where it was renewed by the introduction of ZrC14 by direct sublimation. The formation of a salt plug in the connecting pipe provided a seal between the chambers. Optimum electrolyte composition, with respect to quality of the metal product (91 pct meeting ASTM standards except for the oxygen content) and current-carrying capability (about 350 amp) was determined to be 16.7 wt-pct NaF-83.3 wt-pct NaCl mixture plus ZrC14 equal to about 3 wt-pct zirconium. A twin-cell design incorporating the unit operations covered by this investigation is proposed.

Jan 1, 1976

By R. Karl Zipf, Z. T. Bieniawski

"SummaryAs part of an effort.to understand the mechanics of fine fragment formation in coal, which is important in studies of respirable dust due to mining, fracture toughness measurements and the strain energy density (SEO) theory were applied to calculate the crush zone size under a cutting tool in coal. This · zone is the major source of fine fragments in the 1 to 10 µm size range. The model used in these calculations is a boundary element program containing a failure criterion based on the SEO theory. The boundary element program calculates linear elastic stresses at numerous points in the coal material ahead of a cutting bit. These stresses arc then input to a subroutine called critical ftaw length and orientation (CFLO) which uses the SED theory to determine the CFLO for a small crack at the boundary element stress computation point. The extent of crushing is based on earlier postulates about . the role of inherent flaws in a fragmentation process. To form 1 to 10 µm fragments requires firstly a local stress strong enough to activate flaws with a characteristic length less than 1 to 10 µm and secondly, a flaw density sufficient to provide an average spacing between flaws also on the order of 1 to 10 µm. The locus of active lO µm ftaws represents the maximum possible extent of fine fragmentation in the 10 µm or less size range assuming that a sufficient inherent flaw density exists. The approach offers a first order approximation to the extent of crushing under a tool tip. The size and shape of the crush zone volume is affected by the attack angle and geometry of the tool.IntroductionFine fragment generation in the 1 to 10 µm size range under the action of a generic coal cutting tool may be explained on the basis of fracture mechanics which suggests two major sources of fine fragments: first in a crush zone near the tool tip and second by shear fracturing. along major macrocrack surfaces (Zipf and Bieniawski, 1988a). In this paper, fracture toughness measurements and the strain energy density theory are used to calculate the crush zone size. This zone represents the major source of fine fragments in the 1 to 10 µm size range and understanding the mechanical factors controlling its size represents a first step toward using fracture mechanics to characterize the ·tendency of various coals to produce undesirable fine fragments."

Aug 31, 1989

By C. J. Walker

The Bureau of Mines undertook a theoretical and laboratory study to determine the feasibility of using ethylene as a tracer for natural gas in underground gas-storage reservoirs. The study indicated that ethylene was a useful gas tracer in underground gas storages. Tracer losses were not excessive. Laboratory tests were conducted at pressures as high as 500 psia in both wet and dry consolidated-sandstone cores, evaluating tracer loss with gas blends containing natural gas with different concentrations of ethylene tracer. Under certain conditions losses were less than 17 percent.

Jan 1, 1966

By Richard L. Jenkins

Systematic sampling, in reconnaissance fashion, of the continental shelves of the United States to define favorable areas of offshore mineral deposits, is one of the long-range marine mineral; programs of the U.S. Department of the Interior. In mid-1966 the Department of the Interior launched its Heavy Metals Program to stimulate domestic output of gold which is in serious short supply. The program is jointly conducted by the Geological Survey and the Bureau of Mines.

Jan 1, 1968

To increase awareness of float coal dust explosion hazards in the mining industry.

Jan 4, 2006

By C. S. ROBINSON, T. M. Romslo

This investigation was conducted jointly by the Bureau of Mines and the Geological Survey to obtain further information on the source and economic possibilities of the copper mineralization exposed on the Copper Giant group of claims, Ajo mining district, Pima County, Ariz. The Copper Giant group of claims was first brought to the attention of the Bureau of Mines by Joseph Hunter (deceased), Phoenix, Ariz., part owner of the claims. In December 1942 these claims, and an adjoining group, were investigated by T. C. Denton, mining engineer, formerly with the Bureau of Mines, and Nels P. Peterson, geologist, Federal Geological Survey. It was concluded the area could not be considered as a source of copper for immed- iate emergency needs and that further investigation of the area, at the time, was not warranted. In the spring of 1948 the lessee, J. H. Greenway Albert, requested Bureau of Mines assistance in developing the property. J. H. Hedges, former chief, Tucson Branch, Mining Division, and Lincoln A. Stewart, mining engineer, Bureau of Mines, made a cursory examination of the property and noted that at numerous places, low-grade copper mineralization appeared on fractures and bedding of the Locomotive fanglomerate and Ajo volcanics, which are thought to be of Tertiary age. During the period of May 11 through 14, 1949, Bureau of Mines engineers3 mapped and sampled two areas of mineral- ization. On June 2 and 3, 1949, the areas selected by the Bureau and three other nearby mineralized areas were investigated by C. A. Anderson and R. S. Cannon, Jr., of the Federal Geological Survey. As a result of these examina- tions, further investigation of certain areas was believed to be merited. The Copper Giant area was selected as the most favorable in which to carry out exploratory and development work. The field work on the project was started in October 1949 and completed in December 1949. It consisted of road building, trenching, sampling, topo- graphic and geologic mapping, diamond drilling, and logging of core. Samples taken on the project and during preliminary examinations totaled 64, of which 63 were surface samples. Diamond drilling, started October 10 and completed December 7, consisted of two holes for a total depth of 1,542 feet.

Mar 1, 1952

To improve electrical safety and lengthen light bulb life on trolley haulageways. Approach A resistor inserted in series with each pair of light bulbs, decreases the voltage applied to the bulbs and eliminates heavy arcing when voltages rise. How It Works Under certain conditions, incandescent light bulbs connected directly to a 300-volt d-c trolley wire can be a hazard, particularly during weekends when electrical equipment is nut in use. When little electrical power is being used, the voltage (on the trolley lines and at the substation) can rise to a value which will destroy the bulb filament, cause arcing, and damage the bulb holder. In one coal mine where light bulbs in certain locations fre¬quently failed, the problem was overcome by inserting a 100-ohm, 50-watt resistor in series with each pair of light bulbs. The light bulbs are rated at 300-volts and 100-watts. Figure 1 shows the light bulbs and resistor circuit. This resistance was added in order to reduce the current through a short circuited bulb holder, from several hundred amperes to a much safer value of 3 amperes. However, the resistor in series with each pair of light bulbs, also reduces the voltage across the lighted bulbs to approximately 240 volts during periods when the trolley line voltage is up to 300 volts. With this arrangement, no light bulb failures occurred over a 6-month period. The resulting light reduction has not been objectionable.

Jan 1, 1976

By Raymond M. Stateham

Microseismic noise rates and slope movements were measured in an unstable area along the north wall of the Tripp-Veteran pit, Kennecott Copper Corp., Ruth, Nev. Low-noise, wide-band microseismic geophones were located at various points in the wall, and the change in distance across open fractures, resulting from instability, was determined by repeated measurements between fixed points set on each side of the fractures. The microseismic noise rate increased and decreased with corresponding increases and decreases in the rate at which the fractures opened. The microseismic noise rates and changes in width of the fractures show excellent agreement, and the two types of measurements complement each other in monitoring the progress of pit wall failure.

Jan 1, 1971

Create two air splits along the longwall face to isolate the shearer-generated dust to the immediate face area, maintaining a cleaner split of air in the workers' walkway.

Jan 1, 1994

By David K. Ingram

Research performed by the U.S. insurance industry has determined that mine subsidence is uninsurable. Consequently, the insurance industry has decided not to voluntarily offer mine subsidence insurance. The U.S. Department of the Interior has long been investigating the effects of mine subsidence. These investigations have resulted in Federal regulations and controls of mine subsidence. This U.S. Bureau of Mines report generally describes mine subsidence, the development of mine subsidence insurance programs, and the eight current mine subsidence insurance programs in the United States. The States that have these subsidence programs include Colorado, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, West Virginia, and Wyoming. Major aspects of the programs include history, administrative and operational procedures, insurable structures, recognition of mine subsidence, major exclusions, claims, insurance premiums, and the economic health of each program. Addresses of agencies involved with mine subsidence insurance are also given. Information within this report can be useful for residential and commercial property owners and mine operators. States that are considering starting or have an existing mine subsidence insurance program can also use this report as a model for initiating or modifying their programs.

Jan 1, 1993

By J. F. Messerly

The purity of three specially prepared samples of benzene was determined with an adiabatic, low-temperature calorimeter with automatic control of shield temperature. Extensive measurements were made on each sample to determine how variations in operating procedures affect melting-point and freezing-point as well as purity data obtained by the calorimetric method. Detailed results of the investigations are presented, and effects of different operating procedures are discussed, together with problems encountered in interpretating experimental results.

Jan 1, 1963

Vanadium, molybdenum, and a titanium-10 percent vanadium alloy were evaluated for their susceptibility to stress corrosion cracking in a number of corrodents. Tests were conducted utilizing conventional U-bend techniques with subsequent evaluation in a pneumatic constant-load apparatus. Vanadium and molybdenum were generally resistant to stress corrosion cracking in the media studied. U-bend specimens of vanadium showed evidence of stress corrosion cracking in 6 li hydrochloric and 18 li sulfuric acids; however, tensile stress specimens exposed to these solutions did not exhibit stress cracking. Similar results were obtained when U-bend specimens of molybdenum were immersed in 10 percent formic acid. Titanium-10 percent vanadium alloy was susceptible to stress corrosion cracking in 10-percent (2.85 li) hydrochloric acid solution. Heat treating the alloy greatly reduced its corrosion rate and its susceptibility to stress cor-rosion cracking in this medium.

Jan 1, 1965