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By M. O. Serbousek

The load-transfer mechanics of fully grouted roof bolts in coal mines have been investigated in laboratory and analytical studies. The purpose of this Bureau of Mines research is to increase understanding and better interpret data from routine field pull tests and to develop a numerical model of a grouted bolt that can be used in a global computer model of a mine roof. Analytical studies using closed-form solutions and finite-element techniques were compared to experimental results. Laboratory work includes variation of bolt length, hole diameter, and grouL type. Pull tests were pel'fol·med on 4-, 2-, and I-ft bolts in holes of 1-and I-3IB-in diameters. Both polyester resin and inorganic grouts were used as the anchorage medium. Strain gauges were installed on the bolts at several locations to observe the rate of load transfer from the bolt through the grout to the rock mass when a force was applied at the bolt end using standard jack pull testing procedures and equipment. The average anchorage length of 4-and 2-ft bolts was 22 in. Grout type and hole size variations did not produce a significant effect on the rate of load transfer from the bolt to the rock.

Jan 1, 1987

By B. R. Eichbaum

To develop technology to assure an ample supply of zinc and to reduce environmental pollution, the U.S. Bureau of Mines investigated alternatives to the roast-leach process for treating complex sulfide concentrates. Previous studies proved that low-grade zinc sulfide (ZnS) concentrates could be leached using chlorine-oxygen to produce zinc chloride (ZnCI2). The process involves high energy requirements for evaporating the pregnant solution to produce anhydrous ZnCl2 needed for electrolytic cell feed. An efficient hydrometallurgical process would facilitate treatment of lower grade ores than can be used in conventional processing and would render roasting unnecessary. An alternative method was devised for recovering ZnCl2 from solution. Zinc diammine chloride [Zn(NH3)2CI2] was precipitated from solution by adding ammonium chloride (NH4CI) and sparging with ammonia (NH3) to a pH of 6 to 7.5. The spent solution was treated with calcium hydroxide [Ca(OH)21 at 60° to 80° C for 1 to 4 h to remove remaining zinc and NH3. The Zn(NH3)2CI2 was heated to 300° to 400° C to remove NH3 and produce anhydrous ZnCI2. A possible flowsheet was devised and is included.

Jan 1, 1991

By C. B. Daellenbach

A prototype particulate size analyzer system was developed that would rapidly determine size distributions of homogeneous and two-mineral materials in the 74-micrometer (200-mesh) to 7-micrometer size range. The system sizes particles in a series of hydrocyclone elutriation steps and senses the weight of the five sized fractions by nuclear attenuation techniques. Size distribution of materials was determined from experimentally developed mathematical relationships that existed between particulate weight and the measured transmittance of gamma rays from an Americium-241 source. In the developmental phases, size distributions of three minerals (quartz, magnetite, and hematite) and a laboratory prepared two-mineral mixture of quartz and magnetite were accurately determined by the prototype system. In later stages of the investigation, semiconcentrates, an intermediate magnetic product from a taconite plant, were evaluated. Using 25-gram feed samples of this industrial material, the analyzer system was found to predict weight percentages for individual size fractions with an accuracy of ±0.85 percent or better at a 95-percent confidence level.

Jan 1, 1974

By R. E. Peterson

A reduction roasting/magnetic separation/flotation process for beneficiating oxidized taconite from the western Mesabi iron range in Minnesota was evaluated in a Bureau of Mines research program to insure an adequate supply of raw materials for future ironmaking and steelmaking needs. The research was performed on a sample containing 35.4 pct iron and representing a deposit of approximately 2 billion tons of raw materials. An average of 1,419 lb of oxidized taconite and 37 lb of lignite reluctant per hour were fed to a 35 -foot rotary kiln in which the iron oxides were converted to artificial magnetite. The kiln was heated with pulverized lignite and natural gas. Most of the dust collected from the kiln exhaust gas was pelletized and recycled to the kiln. Magnetic separation and cationic flotation of the roasted material in a 900-lb/hr pilot plant produced a concentrate analyzing 67.9 pct iron and 4.9 pct silica and containing 69.2 pct of the iron in the kiln feed.

Jan 1, 1981

By R. E. Perry

To develop new or improved flotation methods for beneficiating low-grade red iron ores, the Bureau made many bench scale and continuous anionic flotation tests on ferruginous sandstones and calcareous iron ores from the north-eastern part of the Birmingham, Ala., iron district. The ores contained about 21 to 36 percent iron, a to 11 percent lime, and 22 to 64 percent silica. Production of iron concentrates containing 48 to 52 percent iron was technically feasible in batch tests, and the iron recoveries ranged from 85 to 92 percent. In continuous tests 49 to 51 percent iron products were obtained with 80 to 90 percent recovery.

Jan 1, 1962

By J. E. Chilton

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro-chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1-to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light-emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 2010

By E. C. Strycula

Solid-state equipment offers a number of potential advantages in the coal mining industry. These advantages can only be realized, however, through careful and judicious design of the control and protection circuitry. Problems relating to the interaction of solid-state equipment on the electrical system and the special design considerations which apply to solid-state circuitry are examined. Design guidelines are provided for solid-state applications in the areas of: (a) equipment operated from a DC trolley wire, (b) drive systems for surface mining equipment, (c) AC motor starters, and (d) electromagnetic interference.

Jan 1, 1981

By T. G. Mayhew, A. A. Bergeron, R. J. Mahany

This report describes an operational communications system which provides remote intra-terrestrial wireless transmission of environmental information. Design and modification specifications of requisite equipment are included along with a detailed description of system operation

Jan 9, 1976

By John R. Shattuck

The Shasta and California Iron-ore deposits are 14 miles northeast of Redding, Shasta County, Calif.; and since 1907 have produced more than 300,000 short tons of exceptionally pure iron ore. Although some ore was mined and smelted from 1907 through the First. World War, most of it has been produced from 1942 through 1945 for use in making heavy ship ballast and concrete anchorages for mines. Irregular masses of magnetite, ranging from lumps of a few tons to pods containing about 25,000 tons, occur associated with skarn near the contact between the McCloud limestone and a younger granitic intrusive. Some of the deposits are low-grade, whereas others are nearly pure magnetite. Selective mining and hand sorting are necessary to produce a high-grade product. Investigation of these deposits by the Bureau of Mines included 2,910 feet of diamond drilling, some surface sampling of the principal mineralized zone and beneficiation tests. Resulting factual data are given in the body of this report.

Jan 1, 1948

By Graham W. Marks

This report is the fourth of a series concerning the development of spectrochemical methods for the analysis of ore samples and related Metallurgical materials by the total-energy method. In this report, the application of this method to the determination of thallium is discussed. This element lies in group III of the periodic tale; one other Clement of this group; indium, has already been investigated.

Jan 1, 1949

By J. E. Chilton

Underground miners may be exposed to hazardous quantities of toxic gases, such as carbon monoxide (CO), generated from mine fires or explosions. Every underground miner is required to carry a filter self-rescuer (FSR), which when operated will remove CO from the miner's breathing air. In addition, every underground miner must have a self-contained self-rescuer (SCSR) near the worksite that will supply breathing oxygen. In many situations, miners do not know when to don either rescuer since they do not know if there is a fire in the mine, nor do they carry instrumentation necessary for the detection of the toxic, colorless, and odorless fire product CO. If each miner carried a personal CO alarm, which would respond to high concentrations of CO, the miner would then be alerted when to don either the FSR or SCSR and exit the mine. A prototype personal miner's CO alarm called PEMCOAL was developed by the U.S. Bureau of Mines. The PEMCOAL unit is small enough to be carried on a miner's belt, has a flash lamp visual alarm, requires no calibration for use, and uses a chemical sensor that changes color by reaction with trace quantities of CO. The chemical sensor was tested at concentrations of CO from 10 to 1,000 ppm, at temperatures from 5° to 40° C, and with several potential mine gas interferents. The PEMCOAL alarm times were sufficiently fast to warn miners before they are exposed to hazardous quantities of CO.

Jan 1, 1989

By O. M. Schaus

The following is a description of the methods employed at the Eureka-Asteroid mine, which is situated on the Gogebic range, at Ramsey, Mich. The mime is operated by the Castile Mining Co. under the direction of Oglebay Norton & Co. This paper has been prepared in accordance with an outline furbished by the United States Bureau of Mines, and in one of a series, on mining methods and costs covering the principal minim operations throughout the United States. ACKNOWLEDGMENTS The author acknowledges the assistance of the mining organization of the Castile Mining Co. in the preparation of this paper.

Jan 1, 1930

By R. H. Dickson

This paper, which describes the milling practice of the Verde Central Mines, Inc., is one of a series on milling methods and costs being prepared by the United States Bureau of Mines. GENERAL DESCRIPTION The Verde Central concentrator is located in Walnut Gulch, about 1 mile west of Jerome, Ariz., and on the Jerome-Prescott highway. It is about 1,000 feet distant from the main shaft of the Verde Central mine and treats ore from this mine only. The mill is connected with the main shaft of the mine by a 24-inch gave railway, over which the ore is hauled in 5-cubic yard capacity, rocker, side-dump cars, by a 3-ton Brookville gasoline locomotive.

Jan 1, 1931

By E. R. Bauer

The U.S. Bureau of Mines is investigating strata interactions associated with mining of multiple coal beds to provide the mining industry with improved methods of planning and developing multiple coalbeds, conserving resources, and increasing the safety of underground coal mining. This study involves analytical predictions and underground observations of longwall development ground control problems at a south-central Pennsylvania coal mine affected by subsidence induced by multiple-seam mining. As predicted, strata interactions were found in upper mine areas mined over lower mine gob. Observations revealed roof deterioration accompanied by excessive water inflows in the first 170 ft after crossing the gob line as mining entered and exited the subsided area (over the lower mine gob). In contrast, superimposed mine areas and areas mined a substantial distance out over the gob showed no signs of interaction with previous lower seam mining, again as predicted.

Jan 1, 2010

By A. L. Engel

In recent investigations of chloride Volatilization of gold at the Reno Station, it was found that the addition of small amounts of copper and NaCl to the charge brought about improved volatilization of the gold. The investigations described in this report were concerned with the recovery, in an aqueous medium, of fumes from chloride volatilization of gold. It was attempted to discover a suitable aqueous medium that would permit absorption, solution, or precipitation of all the volatilized gold immediately upon contact with the medium. A simple laboratory apparatus was employed to produce fumes by volatilization. To this furnace was attached an absorption train consisting of a series of chambers containing the aqueous medium, through which the fumes were drawn by suction. A satisfactory synthetic ore that contained metallic, gold in a quartz-matrix was made and utilized, enough. gold being present in a' small amount of material to permit an accurate, metallurgical balance of the volatized values' to be obtained in all the experiments.

Jan 1, 1949

By Paul R. Thimas, Edward H. Boyle

"The Bureau of Mines evaluated the long-term cost and availability of primary gold production from 135 mines and deposits worldwide. Collectively, the evaluated countries represent 93 pct of world gold production. Total recoverable gold available (as of January 1984) from a subset of 111 significant producing mines and developing deposits in 13 market economy countries (MEC's) is estimated at 810 million tr oz. The Republic of South Africa is estimated to account for 87 pct of total recoverable gold. The United States and Canada account for 4 and 4.5 pct of the total, respectively. Eighty-three percent of total recoverable gold is available at a constant 1984 break-even price of $400/tr oz, and 70 pct is available at $300/tr oz. South Africa accounts for 90 pct of the gold available at $400/tr oz or less.Major conclusions are that (1) South Africa should remain the largest world producer through the year 2000, (2) annual MEC output in 2000 should not be significantly different than current output given constant 1984 gold prices of more than $300/tr oz, and (3) there may be a significant decline in production after 2010 in the absence of major new discoveries and continued development of new mines to offset the depletion of the South African mines. INTRODUCTIONSince the late 1970's the world gold mining industry has been characterized by dynamic growth in production and volatility in price. World production in 1983 was almost 15 pct greater than in 1980, and the short-term trend continues upward. Annual dollar-based price changes since the early 1970's have been unprecedented in both magnitude and volatility. This commodity, which sold for $35/tr oz3 for over a third of a century, reached an annual average $612/tr oz in 1980. Until 1980, the future price of gold seemed set on an upward trend. Since that year, however, world gold prices have fallen by over 50 pct to slightly over $300/tr oz at the end of 1984.Against this background, this study was undertaken to determine (1) the level of world demonstrated gold resources, (2) total and annual availability of gold mine production, (3) long-run production costs per operation and by national aggregates, (4) the economic and technical factors that impact upon cost and availability, and (5) probable future mine production and cost trends."

Jan 1, 1985

By William H. Pailes, Vincent Castronova, Daniel Lewis, Norman L. Lapp, George Goodman

"INTRODCJCTIONAlveolar macrophages are free lung cells located on the surface of small airways and alveoli. These phagocytes play an important role in the protection of the lung against airborne bacteria and particles.1 However, hyperactivation of pulmonary phagocytes can lead to excessive secretion of enzymes and reactive oxygen species which could result in lung injury, emphysema, or fibrosis.2,3 Analysis of bronchoalveolar lavage effluents for cell types and cellular activity has yielded information concerning the etiology of various pneumoconioses. For example, emphysema associated with inhalation of coal dust or cigarette smoke has been related to enhanced secretion of reactive oxygen species from alveolar macrophages.4-7 In contrast, hypoactivation of alveolar macrophages has been associated with inhalation of diesel particulates"" and has been related to increased susceptibility to pulmonary infection. s Inhalation of cotton dust has been associated with dramatic increases in lavagable polymorphonuclear leukocytes9 while pulmonary sarcoidosis and silicosis have been related with high numbers of lymphocytes in lavage effluentsl0,11The objective of the present study was to obtain lavage effluents from 8 control subjects, 8 healthy power plant workers exposed to fly ash, 1 healthy coal miner, and 1 rock driller with acute silicosis. These effluents were analyzed for total numbers of alveolar macrophages, lymphocytes and neutrophils and for secretory activity of alveolar macrophages. Data were then analyzed to determine what response patterns were characteristic for given dust exposures.METHODSSelection of SubjectsThe 8 control subjectS were all adult males from the area of Morgantown, WV. Two subjects among the controls had smoked cigarettes for approximately three pack-years and had stopped more than ten years ago. The 8 power plant :workers were all healthy adult male employees of a power facility in Hatfield, PA, approximately thirty miles from Morgantown. One of the power plant personnel was a comparable ex-smoker. The remaining subjects were all lifelong non-smokers. The coal miner was a healthy non-smoking male from Morgantown, WV. The rock driller was a patient under treatment with corticosteroids for acute silicosis. He had shown considerable clinical improvement with this treatment but still manifested significant radiologic and pulmonary functional abnonnalities at the time of lavage. The mean age of the 8 control subjects was 36 years (range: 31 to 49 years); the mean age of the remaining subjects studied was 38 years (range: 29 to 53 years)."

Jan 1, 1990

By Nan C. Jensen, Oliver Bowles

Stone , the foundation of the continents and the floor of the oceans , is one of the most substantial and enduring of all substances that constitute the material universe . Stone furnished rude shelter for aboriginal man , and through all succeeding ages it has provided a lasting and serviceable structural material . Limestone is one of the most widely used building stones .

Oct 1, 1947

By L. B. Berger

Studies showing the effect of mixing hot exhaust gases with tie intake air of a four-stroke-cycle Diesel engine are described. The results indicate a marked increase in carbon monoxide in tip exhaust gases, a decrease in oxides of nitrogen, and no significant effect on aldehydes. The increase in carbon monoxide was greater at higher fuel-air ratios and was caused partly by the increase in fuel-air ratio end partly by the decrease in oxygen concentration resulting when exhaust has was added. The application of these results to the use of Diesel engines underground is considered.

Jan 1, 1940

By A. E. Sands

The Bureau of Mines, S. Department of the Interior) at, its Morgantown., W. Va., station, operating under a cooperative agreement with West Virginia University, is conducting research and development work on the problem of producing synthesis gas from coal. An important part of this work is the study of the gas purification necessary to meet the rigorous standards required to render the gas suitable for use in the Fischer-Tropsch synthesis of liquid fuels. One of the most detrimental impurities is sulfur in all forms, the maximum amount that can be tolerated being one-tenth of a grain per hundred cubic feet. Concentrations as low as this require the use of precise analytical methods to evaluate the performance of processes used for removing sulfur. At the same time the analytical methods should be rapid in order to reveal the failure of purification before damage to the expensive synthesis catalyst results. Although sulfur in unpurified gas is generally present as hydrogen sulfide and as organic sulfur compounds, the latter may be converted to hydrogen sulfide for analytical purposes. Thus a suitable method for the determination of traces of hydrogen sulfide may also be used for the determination of organic sulfur.

Jan 1, 1949