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By K. Thirumalai

This study forms a part of Bureau of Mines continuing research on thermal fragmentation of rocks. The potential of internal heating techniques for rock fragmentation is discussed. A concept of rock fragmentation with rapid inter¬nal heating of a localized inner volume of rock is advanced The energy required for rock fragmentation is made available by creating a required vol¬ume of localized heating. The fragmentation of rock using the proposed method is analyzed and qualitatively compared with the results of experiments with Charcoal granite, Dresser basalt, and Sioux Quartzite. High frequency dielec¬tric heating below 100 MHz is used in the study as an example to examine the working of the concept. The selection of operating conditions for the experi¬mental heating is explained. Fragmentation of Charcoal granite and Dresser basalt test rock blocks is achieved for localized heating below 550° C. The heated volume required for fragmentation is observed to be less than 2 percent of the test block volume and the electrical energy consumption is in the order of 3.5 to 6 5 kwhr/m3 The method offers a possibility for in situ fragmenta¬tion of rocks, favorable for internal heating. The method is highly dependent on rock properties governing internal heat generation The efficiency of dielectric heating in the experimental study is observed to increase with increasing dielectric loss of the rock material, ranging from about 10 percent in Sioux. Quartzite to about 50 percent in Dresses basalt

Jan 1, 1970

By G. L. Gates

The waters used to waterflood the Wilmington oilfield were studied by the Bureau of Mines, in cooperation with the city of Long Beach, Calif. Increases in the pressure of the injection wells indicated that they were being plugged by materials suspended in the waters. This study was made to identify the suspended materials, determine their origin, and find methods of preventing their formation. The suspended oil-coated materials were iron sulfide, barium sulfate, calcium carbonate, clay, and sand (or silica). Results indicated that the sulfide, which was as high as 90 milligrams per liter, was the product of sulfate-reducing bacteria. The injection of ocean water increased the sulfate content of the waters in the petroleum reservoirs from 3 to 250 milligrams per liter, thereby furnishing sulfate for growth of the bacteria. The waters were supersaturated with barium sulfate. Laboratory tests showed that sulfide could be removed from the waters by adding iron at a cost of 1 to 2 mills per barrel. The solubility of iron sulfide and calcium orthophosphate in the injection waters was also determined.

Jan 1, 1975

By Thomas Novak, Jeffrey L. Kohler, Joseph Sottile, Steve J. Gnapragasam

Modern underground coal mines can be very large, having a total connected load in excess of l5 000 hp. These mines generally have many miles of high-power conveyor belts and 15 or more miles of high-voltage power cables at distribution voltages of 12.47, 13.2, 13.8, or 14.4 kV. The shielded cables used in mine power distribution systems have a significant level of capacitance, on the order of 110 pF/ft. This level of capacitance, in an extensive power distribution system at today's voltage levels, can cause significant charging currents during a ground fault. This paper addresses the potential detrimental effects of capacitance charging currents during line-to-ground faults in mine power distribution systems. A representative mine power system is modeled, and simulations with faults at various locations are conducted to evaluate the effects of this capacitance on the level of fault current and relay selectivity. This paper also includes results of capacitance measurements made on mine power feeder cables used to validate the simulation model.

By Virgil Marple

In the summer of 1979 the University of Minnesota Mobile Laboratory (UMML), designed for the analysis of airborne particles and gases was used to study fugitive dust from an open pit coal mine. The analysis consisted of determining the particle size distribution and concentration of dust from various mining operations, such as blasting, draglines, loading, roadways and bottom scrapers. For some operations the particles size distribution and concentrations were determined at varying distrances. Details of the dust concentration within the plumes as the plume passed the UMML were measured with an optical particle counter. For line sources, such as roadways this enabled the calculation of the particle flux at the sampling location. In addition to the standard instruments associated with the UMML, the applicability of some new instruments were investigated. These included a uniform deposit cascade impactor and a flux meter. Finally, a technique in identifying plume origins which utilized elemental X-ray flourescence analysis of filter samples was shown to be effective.

Jan 1, 1980

By Julius Roth

Flyrock is the source of most of the injuries and property damage in a majority of blasting accidents in surface mines. A quantitative correlation between shot conditions and maximum flyrock range can be used to define a "blasting area" in which no personnel or equipment should be present during a shot. The approach used was to develop a model that correlates shot conditions and initial flyrock velocities and permits computation of flyrock range from ballistic trajectories. The Gurney formula for velocity of explosively-propelled plates or fragments was adapted to explosively-propelled flyrock from vertical rock faces or from bench tops. The modified Gurney formula was then "calibrated" with measured flyrock velocities from mining and explosives literature. Charts were then developed for possible field use which give maximum flyrock range as function of shot conditions. The model indicates that for flyrock from vertical faces, borehole diameter, minimum burden and height of explosive column define maximum flyrock range for a given explosive, shot in a given rock. For flyrock originating from bench tops, flyrock range appears to be controlled by the distance of the top of the explosive column to the borehole collar, by total explosive load per borehole and, to a lesser extent, by borehole diameter.

Jan 1, 1979

By D. D. Southworth

In 1981, 1982, and 1983, the Bureau of Mines examined the potential for lode deposits of platinum-group metals (PGM) in the Goodnews Bay ultramafic complex, Alaska. The complex consists of the Red Mountain, Suzie Mountain, and Smalls River ultramafic bodies and displays concentric zoning of rock types similar to complexes in southeast Alaska, British Columbia, and the Ural Mountains in the U.S.S.R. Results of the study indicate that platinum is preferentially associated with chromite and magnetite in the dunite core of the complex, and palladium is preferentidlly associated with sulfide minerals in the outer clinopyroxene-rich zones. the most promising targets for PGM lode deposits are the chromite-rich dunite at the heads of Fox Gulch and Squirrel Creek and iron-nickel and iron copper sulfide-bearing magnetite clinopyroxenite and hornblende-rich rocks outward of the dunite core, also in the Fox Gulch-Squirrel Creek area. Significant placer reserves are present in the unmined, deeply buried placer ground in the lower Salmon River Valley, and also in tailings from previous dredging.

Jan 1, 2011

By BUREAU OF MINES

This report is submitted in accordance with the provisions of the Synthetic Liquid Fuels Act of April 5, 1944 (30 U.S C. 321-325, as amended), which require that: "The Secretary of the Interior shall render to Congress on or before the first day of January of each year a report on all operations under this Act." Owing to the broad scope of the content and the diversity of interests represented, the Annual Report for 1953 has been divided into two separate publications. Each has been published by the Bureau of Mines as a Report of Investigations, and the respective titles follow: R. I. 5043, Part I - 011 From Coal. R. I. 5044, Part II 011 From 011 Shale. - Identical in each report, the introduction summarizes research progress made in 1953 under the entire Synthetic Liquid Fuels program. A free copy of each of these publications may be obtained by a written request to the Bureau of Mines, Publications Distribution Section, 4800 Forbes Street, Pittsburgh 13, Pa. The R. I. number and title of the publication desired should be indicated.

Apr 1, 1954

As mine haulage vehicles become larger, the danger to a driver during a fire emergency is increased by the greater height of the cab above ground. Also, property damage due to fires on bigger trucks can be substantial. To solve this problem, the Department of Interior's Bureau of Mines, through two research and development contracts with FMC Corporation, San Jose, California, has developed two reasonably priced, reliable automatic fire sensing and suppression prototype systems for large haulage vehicles. At the onset of the large mobile equipment fire protection contract effort, it was learned that fires were frequently experienced in open-pit mine haulage equipment, especially large trucks. As the size of equipment has grown, so has the hazard presented to an operator forced to leave his truck in a hurry when fire breaks out and his normal path to the ground is blocked by flames. His only recourse is to jump from the cab platform to the ground, and the one-story drop of 10 feet or more can severely injure him. It is with these factors in mind that a program was undertaken to provide a fire detection and extinguishing capability tor the large mobile equipment, especially trucks, used in open pit mines.

Jan 1, 2012

By D. A. Reynolds

[A few studies on the relationship of the fusion temperature of the ash of coke to that of the corresponding coal have been made on commercial high-temperature cokes. R. J. Rose3/ in 1921 compared the' fusion temperatures of the ashes of 10 coals and. the cokes produced from them and concluded tat they were in such close agreement that either figure could be used. More recently, Quarfort4/ found that the ash of coke fused at a somewhat lower temperature than that of the original coals As the ash of a coal and that of the coke produced therefrom have the same origin their chemical composition should be identical, provided that carbonization has not altered the inorganic, or ash-forming, constituents of the coal, and such alteration seems highly improbable. However, it has been shown5/ that coke is liable to contamination by iron during crushing and preparatory to sampling. Pieters6/ found that coke ash was cantaminated in this manner up to 0.4 percent. extraneous iron would lower the ash-fusion temperature because such iron may form ferrous silicate, which is readily fusible,7/ These results provide a basis for the prediction that the ash of coke will fuse at a lower temperature than that of the corresponding coil., especially if the fine grinding of the coke was done by rubbing surfaces of iron, as in a disk pulverizer or bucking plate.]

Jan 1, 1940

By James F. Neill, O&apos

Investigation of the Gilley fluorite deposit was based upon examinations made by several of the Bureau's mining engineers. Fluorspar was found in the dump talus of sloughed and water-filled trenches and shafts, and there were indications that faulting or other dynamic distortions favorable to deposition of this mineral in minable quality and quantity might exist. The inference was based upon a field study of the area and its comparison with fluorspar deposits in Kentucky. The proximity of this deposit to the iron furnaces at Gadsden and Birmingham was a factor that influenced its investigation, as the demand for metallurgical grades of this critical mineral is acute. The present supply for the district is obtained from out-of-State sources, and the value of any local deposit would be enhanced by the saving in freight charges. The Gilley fluorspar deposit is 17 miles east of Gadsden and 50 miles northeast of Birmingham, Ala. Mineral deposits occur as thin veinlets and small bunches of fluorite in upturned bode of siliceous limestone. The ore-bearing structure is a reverse fold, and the mineral deposit appears as a replacement along crumbled zone fractures of the contorted limestone.

Jan 1, 1950

By P. L. Swanson, F. M. Boler

The U.S. Bureau of Mimes conducts research at the Galena Mine, Wallace, ID, with the aim of mitigating the effects of rock bursting. Destress blasting is commonly used as a stress control technique at the mine. A digital seismic array and an array of borehole pressure cells (BPC's) had been installed near the site of a stope undergoing mining and periodic destressing. The instrumentation was being monitored at the time of a destress blast of the 46-99 stope. No significant seismic events occurred coincident with the destress. However, the destress was followed by a 21/2-week period of increased seismic activity, including two damaging events on February 7, 1990, at 034500 (hour, minute, and second) and 122020 Pacific standard time. BPC measurements indicated coseismic ground pressure changes on the order of 200 to 300 kPa associated with the damaging events. Fault plane solutions and dislocation models established that stress changes induced by the event at 034500 may have been significant in promoting the occurrence of the event at 122020. Theoretical investigations suggest that applying knowledge of the existing stress field, an understanding of rock burst mechanics, and fracture mechanics principles can improve destress effectiveness.

Jan 1, 1993

By Alexander May

The Bureau of Mines conducted studies to determine if phosphogypsum, a waste material from the processing of phosphate rock, contains hazardous toxic materials as defined by the Environmental Protection Agency (EPA) and whether leaching of these toxic materials and radium may occur. Samples of the phosphogypsum stockpiled material were evaluated using the EPA extraction procedure, atomic absorption, neutron activation, x-ray diffraction, and chemical and physical means. Radiological tests performed used both the germanium-lithium and emanation methods. The data show that the phosphogypsum stockpiles are not hazardous toxic waste as defined by EPA criteria. Trace elements and radium are not leached from the phosphogypsum stockpiles. Absorption of trace elements and radium by phosphogypsum is the major reason for their not being leached. The standard error of measurement of radium concentrations was 4.7 pCi/g.

Jan 1, 1983

By Mark S. Redfern, Kim M. Corneliusa, Christopher A. Hamrick, Sean Gallaghera

Coal miners often handle heavy electrical power cables, weighing up to 10 kg per meter. These cables are manually lifted and attached to the mine roof to prevent damage from mobile underground equipment. Data suggest that workers who commonly perform cable handling tasks experience a high rate of lost time back injuries. In this study, six male underground miners performed a total of 12 cable-hanging tasks in standing, stooping, and kneeling postures, during which kinematic and ground reaction force data were collected. Reductions in vertical work space were found to result in a linear increase in the peak moment experienced by the lumbarspine (p<0.05). In restricted postures, peak moments were not significantly different in stooping vs. kneeling postures (p>0.05). Average lumbopelvic flexion during the tasks was highest in stooping conditions, followed by standing and kneeling exertions (p<0.05). Implications of this data with respect to design of cable handling tasks are presented and discussed. Keywords: Biomechanics, posture, low back pain, restricted workspace, mining

By J. A. Bartol

A survey was made of accident data and operating practices related to overloading and uneven load distribution on haulage trucks in noncoal open pit mines. Safety and economic aspects were analyzed. A bibliography of the literature was prepared. Review was made of available or projected systems for weighing or load indicating that might be applied to haulage trucks. A model specification was prepared for an overload detection system. Several promising systems for overload detection were identified. One was installed and tested briefly in a 170-ton rear dump truck in a copper surface mine.

Jan 1, 1982

By W. R. Crank

[Rock bursts are phenomena associated with mining operations, particularly with deep mining, although they occur throughout a wide rump, of depth, from 600 feel downward. The intensity is usually in direct proportion to the depth, varying from a loosening and sloughing off to a violent rupture, giving rise to the term, "explosive rock." The more or less violent breaking of rock in mine working, tins been variously designated as " flaking," "pressure hoists," "strain bursts," "bumps," "quakes," and "air blasts," which indicate opinions as to cause and effect. The term "air blast" lots probably beat most widely used, and naturally so, as a more or less rapid movement of air often accompanying the more violent phenomena of rock failure. Furthermore, there is an implied if not definitely expressed degree of magnitude in the action designited by a given term and in the cause and character of the action. For example. flaking, pressure bursts, and quakes are terms ranged to indicate action of increasing magnitude; and pressure bursts, strain bursts. bumps, and quakes are ranged according to the cause and character of the action.]

Jan 1, 1929

By D. W. Bridges, Donald R. Peterson, Masami Hayashi

Techniques are described for recovering about 80 pct of the cobalt and nickel contained in superalloy scrap by anodic dissolution of the scrap and simultaneous electrodeposition of a pure cobalt - nickel alloy at the cathodes in an electrolytic cell partitioned by permeable diaphragms into separate anode and cathode compartments . Superalloy scrap was alternatively prepared for subsequent anodic dissolution either by melting and casting massive scrap into suitably sized anodes , by packing moderate - sized discard scrap in inert metal baskets that subsequently served as anodes , or after concentrating the superalloy portion of grinding debris , by magnetic separation to reject corundum or other abrasives , slagging any remaining abrasives from molten grindings , and finally casting the superalloy metal into anodes . In the processing , purified electrolyte -- 1 N in NiSO4 and in NiCl₂ , and 0.1 N in CoSO4 and in CoCl2 --was charged to the cathode compartments and discharged from the anode compartments at a rate sufficient to overcome the backward migration of ionic impurities from the anodes to the cathodes . Discharged electrolyte was purified by reacting it first with SO2 and next with limestone , and then recirculated to the cathode compartments , in which a 50 pct cobalt - 50 pct nickel alloy was deposited on either blanks of stainless steel or starting sheets of cobalt - nickel alloy . The process was made self - sustaining by either adding H2SO4 to the catholyte feed to throttle the rate of cobalt - nickel deposition , thereby compensating for the slower rate of cobalt - nickel dissolution from the anode and losses occurring in electrolyte purification , or alternatively , adding H₂SO4 to

Jan 1, 1964

By R. H. Hiltz

One of the major hazards in underground coal mining is fire. The inherent hazard of fire is exaggerated by the nature of coal mining restricted areas, the highly combustible nature of coal itself, and a potential for explosive concentrations or dust and gas in the air it becomes imperative therefore to make every effort to eliminate the causes of fires, while providing the most effective means possible to control and extinguish those fires which may occur it has been demonstrated by prior work that the problem of control increases in proportion to the time necessary to institute control procedures. There are several areas of underground coal mining with obvious fire potential. Some of these, like belt heads, have reliantly undergone improvements in standby fire control devices Others, although having fire suppression systems available to them, have not received as complete a systematic study of their problems. Face machinery, particularly those without a water supply, falls in this latter category.

Jan 1, 1973

By Richard W. Lusignea

This report describes a program to evaluate the feasibility of determining roof features which occur in United States coal mines from changes in bolting machine drilling parameters. The ultimate purpose of this effort is the development of an instrumented roof bolting machine which can detect hazardous roof conditions and/or indicate when the existing roof control plan is inadequate. A survey of hazardous conditions occurring in United States coal mines is included, along with the slang expressions for these conditions, and their relative degree of hazard. Specific machine parameters are identified for detecting the specific roof conditions. Measurement concepts are proposed using readily available instrumentation in most cases. Various systems are evaluated and tradeoffs presented. An implementation plan is proposed for developing a prototype system and using it in an operating coal mine.

Jan 1, 1978

By A. J. Kraemer

The properties of crude petroleum continue to interest the Bureau of Mines and constitute an important phase of its major studies on the mineral resources of the United States. The Bureau&apos;s interest in the subject has been intensified by frequent requests for information on the characteristics of crude petroleum from various producing fields. Since its inception the Bureau of Mines has collected and analyzed samples of typical oils and at present has surveyed and classified crude petroleums from nearly all the known oil fields of the Western Hemisphere. Results of these surveys have been presented in various Bureau of Mines publications. (See bibliography, appendix A, p. 145.) The nature and comparative value of crude oils from various countries and the extent to which these oils may be considered potential competitors for markets are of manifest importance to the petroleum industry in all lands, largely because all crude oils, wherever produced, are either actual or potential competitors for a market with all other crude oils. The numerous discussions of foreign production of oil that have appeared in the technical press in the past indicate the great interest of the United States in this subject.

Jan 1, 1937

By E. Kamon

This report summarizes completed research pertaining to the reaction of human subjects exposed to Self-Contained Breathing Apparatus (SCBA) stressors during escape conditions (viz., resistance breathing, C02 breathing, hot air breathing, and static positive facepiece positive pressure breathing) and the development of an automated breathing and metabolic simulator (ABMS). Volume I contains summarizes of the studies performed under this contract. Volume II is an appendix which contains more detailed descriptions of these studies.

Jan 1, 1984