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By Robert P. Vinson

The Bureau of Mines investigated the presence and extent of methane accumulations in mine roof cavities using a full-scale mine model. Methane was released at a constant rate into the roof of a cavity built onto a 700-ft wind tunnel. Two box-shaped roof cavities were used in the study: one had a volume of 114.7 cu ft; and the other had a volume of 57.3 cu ft. Methane concentration was measured at 28 sampling points in the cavities using 21 different combinations of gas emission rates and air velocities. Brattice hung in the cavity helped reduce methane concentrations without auxiliary ventilation. It was also found that the effective ventilation rate increased by a factor of 40 in the large cavity and by a factor of 20 in the small cavity when air velocity was increased from 100 to 600 fpm.

Jan 1, 1978

By John M. Gomes

The Bureau of Mines investigated two techniques for removing CaO from scheelite (CaW04) prior to electrolysis. In the first technique, a crude tungstic oxide (WO3) containing 0.15-percent lime (CaO) was prepared by digesting scheelite concentrates in hot hydrochloric acid. This oxide was used as cell feed to produce tungsten of 99.9-percent purity. The second technique used a high-temperature, two-phase separation, resulting in extraction of 99 percent of the WO3 in the halide-tungstate phase, while 90 percent of the CaO was retained in the silicate phase. Tungsten of 99.9-percent purity was deposited from the halide-tungstate melt after B203 and NaPO3 were added to form an electrolyte. The two methods were compared with a previously developed technique of depositing tungsten from scheelite concentrate fed directly to the electrolytic cell.

Jan 1, 1971

The object of this program was to extend the capabilities of visual paging systems both in size and function. The system developed uses the mine pager phone line for communication, monitoring, and remote control. A central station, using a minicomputer, transmits signals by phase inversion modulation of a 16,384 Hz carrier to as many as 999 remote units. The remote unit addressed returns An echo to indicate that it is functioning and, in the case of monitor units, to convey the monitor data. Magnetically latched display dis[c]s, which can be seen from both sides when posted, are used for visual paging. Lists of the addresses of posted pages, unanswered pages, and non-echoing units are prepared by the central station computer. The system was designed to be intrinsically safe and should operate for three months on a 12-volt lantern battery.

Jan 1, 1980

By R. R. Wells

For several years the Klukwan deposit near Haines, Alaska, has attracted interest as a potential source of iron. Limited field and laboratory investigation has indicated that the deposit contains a large amount of Iron that is recoverable as high-grade concentrate. This report summarizes the results of laboratory beneficiation testing of the Klukwan ore, as represented by six samples submitted to the Alaska Experiment Station of the Bureau of Mines, Juneau, Alaska, Iron is present in the ore as a fine-grained magnetite associated with a pyroxenite type basic rock.. Satisfactory magnetic-separation procedures were developed for the production of concentrates assaying more than 60 percent Fe and 2 to 4 percent Ti02. During the investigation many data were obtained and compiled, but for convenience and clarity data of secondary importance have been omitted or condensed; only the more pertinent test results are discussed in detail.

Jan 1, 1953

By C. B. Manula

Bituminous coal mining in the United States is currently experiencing a period of rapid growth which began in the early 1960's. Future demands are conservatively predicted to rise to 700 million tons by 1980 and to anywhere between 1 to 3 billion tons by the turn of the century. This means a continuous expansion of coal production by a factor of at least two can be expected before the end of the century. Over the last few years, production from underground mining has decreased; yet it is about 50% of the total coal output. In the absence of any discovery of near surface coal deposits, and even after conceding that some deeper deposits can be surface mined with changes in technology it can be reasonably assumed that coal production from underground will continue to play an important part in solving the energy crisis.

Jan 1, 1975

By H. O. McDonald

Solutions containing Cr6+ and sulfuric acid are used in a number of surface-finishing operations. Substantial quantities of chromium and copper are lost and pollution problems are created when the spent solutions are discarded. To minimize the undesirable environmental effects while improving secondary resource recovery technology, the Bureau of Mines is conducting research to detoxify and recover metals from these solutions. Spent etchants are treated to remove copper and reduce Cr6+ to Cr 3+ in an electrolytic cell. The anodes and cathodes are granulated coke. The spent solution is continuously pumped through the electrodes. Hexavalent chromium is reduced to trivalent chromium, and copper is recovered at the cathode. Reoxidation of Cr3+ at the anode was not observed. The removal and recovery of copper reduction of Cr6+ lessen chemical demand and increase efficiency in waste in treatment operations associated with the use of these solutions.

Jan 1, 1980

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate-mines in various foreign countries. This interpretation of the mining laws of Greece was prepared from information furnished by Ralph B. Curren, American assistant commercial attache, Athens, in reply to a questionnaire of the United States Bureau of Mines, transmitted through the courtesy of the commercial laws division of the Bureau of Foreign and Domestic Commerce. INTRODUCTION In his report,3 Mr. Curren states that the source of his information was the Director of Mines of the Greek Ministry of National Economy and the Mining Code of Greece, which was, compiled from existing laws in 1929,4 and which has since been modified by several acts of Parliament.

Jan 1, 1932

By R. M. Santmeyers

This paper presents one of a series of digests of foreign mining legislation and curt decisions that is being prepared in advance of a. general report relative to the rights of American citizens to explore for minerals and own and operate mines in various foreign countries. This interpretation of the mining legislation of Madagascar was prepared from the best information (in French) available in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers, to whom it dill be referred through the courtesy of the Department of State. INTRODUCTION The basic mining law of Madagascar is the decree of 1923, signed at Rambouillet by the President of France on July 19, and published in the Journal Official de Madagascar et Dependances. It has been modified by a number of subsequent laves and regulations, generally of minor importance.

Jan 1, 1933

By Richard A. Dick

Underground blasting in permanently frozen gravel was studied in a 7-by 12-ft drift by running a nonreplicated 2 X 2 X 2 factorial experiment on the effects of type of cut, delay, and explosive on the fragmentation subsystem. Comparisons were made between a V-cut round and a burn-cut round, millisecond delays and half-second delays, and 40 percent special gelatin and 60 percent high-density ammonia dynamite. The number of large blocks in the muck pile) loading time, shuttle car operating time lost because of cleanup needs, length of advance per round, and length of muck pile were recorded and statistically analyzed. None of the blast parameters had a significant effect on the length of advance or length of muck pile, although the half-second delays tended to give a shorter muck pile than millisecond delays. The burn cut required less secondary breakage, less loading and cleanup time, and gave better overall fragmentation than the V-cut. The ammonia dynamite shots required less secondary breakage and less loading time than those using special gelatin. The half-second delays gave better overall fragmentation and required less cleanup time, but the millisecond delays gave a better loading rate. None of the differences between delays and explosives were notably significant.

Jan 1, 1970

By Harley A. Coy

This paper, describing the mining methods and practice at No. 2 mine of the American Zino Co. of Tennessee at Mascot, Tenn., is one of a series of papers issued by the Bureau of Mines presenting the mining methods and costs in various districts throughout the United States. Its purpose is to summarize methods recently put into practice whereby increased efficiency has been effected. These improvements have to do principally with mill-hole mining, slushing, contract labor, and bonuses. In general, this paper supplements earlier articles and brings them up to date. ACKNOWLEDGMENTS The author acknowledges the assistance of M. H. Newman, geologist of the American Zinc, Lead & Smelting Co.; of William Black, assistant superintendent of mines; of P. M. Arthur, director of personnel; and of the engineering staff. The paper has been approved by H. I. Young, vice president and manager of operations.

Jan 1, 1930

By Michael D. Dunn

The Bureau of Mines evaluated a quartz schist formation within the Blue Joint Wilderness Study Area which was identified as having a "high potential" for copper-silver-cobalt-barium resources. Stratiform and remobilized copper occurs near, and bedded barite within, the study area. In addition, the black to gray Proterozoic quartz schist may correlate with the Yellowjacket Formation which contains cobalt-copper-gold-silver deposits at Blackbird, ID, about 30 miles to the south. Eighty soil and 43 rock samples collected across the quartz schist formation were analyzed for gold, silver, copper, cobalt, and barium. During the reconnaissance and sampling, particular attention was given to looking for malachite (copper carbonate) and erythrite (cobalt arsenate, also known as "cobalt bloom"). The sample analyses and geology in this localized area do not provide enough evidence to support the "high potential" designation for copper-silver-cobalt resources. Barium potential still appears high, however.

Jan 1, 1987

By Wesley T. Holmes

This report describes the second phase of an investigation aimed at obtaining a wider knowledge of the problems involved in smelting titaniferous magnetites. Liquidus temperature measurements were made on selected synthetic slag compositions in the Ti02 -A1203 -FeO-Si02 -CaO-MgO system. Both the hot-stage microscope and the strip furnace (melting-holding-quenching technique) were used during test procedure to determine the effects of CaO, MgO, and SiO2 on the liquidus temperature of slags. The liquidus temperatures of slags studied ranged from 1,241° to 1,900° C. The lowest liquidus temperature for each Ti02 plus A1203 plus FeO weight-percent generally occurred when the difference between CaO plus MgO and Si02 was less than 12 weight-percent. In this investigation substitution of either CaO or MgO for SiO2 and MgO for CaO raised the liquidus temperature of more than 50 percent of the reported base slags when Ti02, A1203, and FeO contents were held constant. The results of this investigation may serve as guidelines for determining flux requirements in smelting a wide variety of titaniferous magnetite concentrates or ores.

Jan 1, 1968

By Frank K. McIntosh

The Wood mine area was investigated by the Bureau of Mines in -1941 by a magnetic survey and a gravitational survey. Surface trenches were excavated, and diamond-drill holes were bored at the strongest anomalies developed in common by the two surveys. In the last century', several widely separated bodies of chromite with some magnetite had been exploited in a 'serpentine belt near its contact with schist. At one time this district held a virtual monopoly on the production of chromite. Known ore bodies now are exhausted. Owing to the relatively high specific gravity of chromate compared to normal rocks, a gravitational survey was run to determine which magnetic anomalies were worthy of diamond drilling. Linear feet of trenching totaled 1,710 feet. Ten holes were diamond drilled, which totaled 2,272 feet. The log of the drilling is shown in the text in a tabulation of drill-hole data.

Jan 1, 1948

By E. G. King

Many of the rare-earth oxides are now commercially available in pure form and they have a variety of potential technical uses. Thermodynamic data for these oxides, however, are rather sparse. It is one of the functions of the Bureau of Mines to fill the need for this type of information. This report gives the results of low-temperature heat-capacity and high-temperature heat-content measurements by the Bureau of Mines of lanthanum sesquioxide. The entropy at 298.15° K. was evaluated and heat-content and entropy increments above 298.15° K. were obtained to 1,800° K. The results were combined with the known heat of formation at 298.15° K. to derive heats and free energies of formation at higher temperatures. Sufficient information is now available to permit reliable thermodynamic calculations involving lanthanum sesquioxide within the temperature range 298° to 2,000° K.

Jan 1, 1961

By Fred N. Kissell, Jerry C. J. Tien, Edward D. Thimons

At coal mine working faces, simultaneous application of three basic elements reduces the methane explosion hazard: (1) adequate ventilation, (2) regular monitoring of gas concentrations, and (3) the elimination of ignition sources. This paper reviews the application of these elements in a manner relevant to Chinese coal mines. Adequate ventilation is provided by using the mine entries to convey air for the long distances between the mine portal and the working sections (main ventilation systems) and then using line brattice or ventilation duct (face ventilation systems) to convey air the last hundred meters to the working face where coal is broken and removed. The air quantity provided is enough to safely dilute methane and the air velocity is enough to prevent layering. Gas concentrations are regularly monitored in accordance with regulations using knowledge of the circumstances under which the highest concentrations are likely to be found. Ignition sources are eliminated by ensuring that electrical equipment does not ignite methane, that sparking from cutter picks is minimized, and that smoking by workers is strictly forbidden. Risk-reduction studies using fault-tree analysis have shown that large reductions in explosion risk only result from multiple preventive actions. For example, a ventilation upgrade or a methane monitor upgrade by itself offers risk reductions under 50 pct. A risk reduction of 90 pct. or more would typically require much more. Other studies have shown that the everyday vigilance of those working underground is as important as engineering design.

By R. V. Ramani

This volume, the first of a six volume final report, provides an executive summary of the research and results carried out under a grant from the U. S. Bureau of Mines on underground coal mine ventilation. Under the project, a mine ventilation simulator was developed. Sensitivity of leakage and friction factors on the total quantity and pressure requirements was studied. The simulator was applied to a new mine under development, and to an operating mine, to demonstrate the usefulness of the simulator in ventilation planning and in evaluating proposed changes to existing ventilation system. The titles of the other volumes are as follows: Volume II: Mine Ventilation Network Theory Volume III: User's Manual for PSU/MVS Volume IV: Sensitivity of Leakage and Friction Factors Volume V: Application of PSU/MVS to Ventilation Planning of a New Mine Volume VI: Application of PSU/MVS to the Analysis of Modifications to Existing Ventilation Systems

Jan 1, 1977

By James W. Jensen, Aarne Visnapuu

Experimental modifications have been made by the Bureau of Mines on standard pneumatic rock drills to reduce the noise of the air exhaust, drill steel resonance noise, and noise radiated by the drill body. A close-fitting case and muffler around the drill body, consisting of a metallic honeycomb skeleton filled with viscoelastic absorber on the inside and a durable outer shell, provide both exhaust and drill body noise muff ling and absorption. Drill steel resonance noise is reduced by a constrained-layer treatment consisting of a tubular metal cover bonded to the ouside of the sod by a viscoelastic filler. Damping alloy components have been developed to reduce metallic resonance noise. Combined, these modifications have reduced the drilling noise level in granite from 115 dbA to 97 dbA. Data are presented on the individual and combined effects of these modifications on drilling noise and performance.

Jan 1, 1975

By Manuel Gomez

Bituminous coals having maximum fluidity values in the 40- to 25,400-dial-divisions-per-minute (ddpm) range were carbonized in a continuous, entrained-bed reactor. Carbonization was conducted in an 8-inch diameter, vertical reactor at temperatures from 955° to 1,345° F and at air-to-coal ratios ranging from 4.63 to 16.12 scf/lb of moisture-and ash-free coal charged. Carbonization rates from about 118 to 360 lb/hr, as-carbonized basis, were examined. It was demonstrated that carbonization temperature and air-to-coal ratio must exceed minimum values for continuous operation. Within the operating conditions discussed, highly fluid bituminous coal was carbonized to produce tar and nonagglomerated char. The yield of tar ranged from 21.3 to 38.9 gallons per ton and the char yield ranged from 1,109 to 1,563 pounds per ton, all units expressed on a moisture-and ash-free basis. It was demonstrated that the maximum fluidity and the average size of the coal along with the air-to-coal ratio and the carbonization temperature act together to influence the carbonization product yields and certain properties of the products. Prediction equations were developed from the data for product yields and selected properties of the char, tar, and gas.

Jan 1, 1968

By M. A. Trevits, J. E. Urosek, A. C. Smith, M. P. Valoski

The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate, improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Since wood is the second most abundant fuel available during a coal mine fire, it was decided that series of large-scale wood crib fire tests were needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.

By Peter Grandone, Ludwig Schmict

The injection of oil-field brimJs into subsurface formations containing mineralized water ·now is .recognizud as the most satisfactory and effective means of disposal in Kansas.· Other disposal ·methods, such as impounding brines in evapOTation nonds and controlled diversion into surface streams, have not prov-ed entirely successful, principally. because the volumes of brine to be disposed of were large, the soil f;?xtr~~mely porous, the net evaporation is low, and the rairiiall insufficient fc)r adequati.:~ dilution of the brine. The disposal of brine by subsurfaCE) inj'ection is often: more. expensive than by either of the above surface methods; nevertheless, surface dis:pos?,l ow.ing to the damaging effe-c.ts of· salt water to plant, animal and aquatic life and to potable water supplies has been:a long-continuing problem with many technical, economic, and 'legal·complexiti,2s

Aug 1, 1943