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By T. D. Moore

The use of a partially slotted 6.5-inch-inside-diameter vertical pipe to remove methane from a longwall gob area at a depth of 2,260 feet in the Pocahontas No. 3 coalbed was investigated. The value of gas removed by such a pipe under free-flow conditions was found to equal the cost of the installation in this case. Approximately 25 percent of the available methane passed through the pipe without the use of an exhauster; an additional 10 percent was removed when an exhauster was employed. The diversion of methane through a vertical slotted pipe to the surface permitted the use of increased mining rates and decreased the ventilation air requirements.

Jan 1, 1972

By Donald F. Reed

In its program of investigation of deposits of strategic minerals, the Bureau of Mines did some development drilling from October 1247 to March 1948 at the Pickering Creek deposits, Charter County, Pa., in an endeavor to find an additional source of supply of lead and zinc. Lead mining in Pickering Creek Valley showed great activity from 1851 to 1855; but after this period mining gradually declined until 1870 when all mines were. One small mine did some work from 1917 to 1920. The ores were sulfides of lead and zinc, which were partly oxidized from the surface to the 20-foot level. As zinc was penalized at the reduction works, the ore was sorted at the mine and the zinc discarded. The Wheatley and Chester County veins contained the beet ore bodies in the district. These converging veins are 2 to 5 feet wide. To cut the veins below the old mine working' the Bureau of Mines diamond-drilled eight holes aggregating 2,820 feet. No significant lead-zinc mineralization was found.

Jan 1, 1949

By L. A. Johnson

This Bureau of Mines report presents the analysis of three cores from the Asphalt Wash area of the P.R. Spring tar sand deposit of northeastern Utah. Two tar sand zones are indicated in the Asphalt Wash Area. Total net thickness of the tar sand ranges from 23 to 39 ft, with occurrences between 56 and 263 ft in depth. The sand has average porosity of 24.7 pct of bulk volume, average permeability before and after extraction of 87.5 and 596 md, respectively, and average oil saturation of 58.1 pct of pore volume. Oil gravity averages 10.9° API.

Jan 1, 1975

By Lloyd A. Morley, Alan M. Christman

1. Anonymous. "Getting Down to Earth," booklet 25T, James G. Biddle Co, Plymouth Meeting, Pa. (1970) pp. 1-48. 2. Anonymous. "Megger Ground Tester, Special Instructions," booklet 25-J-1, James G. Biddle Co, Plymouth Meeting, Pa. (1961) pp. 1-16. 3. AIEE Committee. "Application Guide on Methods of Substation Ground¬ing," AIEE Transactions on Power Apparatus and Systems (April 1954) pp. 271-277. 4. AIEE Committee. "Voltage Gradients Through the Ground Under Fault Conditions," AIEE Transactions on Power Apparatus and Systems (October 1958) pp. 669-692. 5. American Standards Association. "American Standard Safety Rules for Installing and Using Electrical Equipment in and about Coal Mines," U. S. Bureau of Mines Information Circular 8227 (1964). 6. Armstrong, H. R. "Grounding Electrode Characteristics from Model Tests," AIEE Transactions on Power Apparatus and Systems (December 1953) pp. 1301-1306. 7. Beck, Edward. Lightning Protection for Electric Systems, McGraw¬Hill, New York (1954) pp. 281-295. 8. Bellaschi, P. L. "Impulse and 60 Cycle Characteristics of Driven Grounds," AIEE Transactions (March 1941) pp. 123-128. 9. Bellaschi, P. L. "Lightning Strokes in Field and Laboratory," Elec¬trical Engineering, Vol. 58 (November 1939) pp. 466-468. 10. Bellaschi, P. L., Armington, R. E., and Snowden, A. E. "Impulse and 60 Cycle Characteristics of Driven Grounds-II," AIEE Tran¬sactions (1942) pp. 349-363. 11. Bewley, L. V. "Theory and Tests of the Counterpoise," AIEE Transac¬tions (August 1934) pp. 1163-1172. 12. Brereton, D. S. and Hickok, H. N. "System Neutral Grounding for Chemical Plant Power Systems," AIEE Transactions on Applica¬tions and Industry (November 1955) p. 315. 13. Bruce, C. E. R. and Golde, R. H. "The Lightning Discharge," Journal of the Institute of Electrical Engineers, London, Vol. 88 (December 1941) pp. 487-505.

Jan 1, 1976

By John Zetterstrom

Increased activity in the beneficiation of taconite, particularly the magnetic variety, has shown the need for more information on the rate of oxidation of magnetite to hematite. This oxidation occurs in the pelletizing step of the beneficiation process. Magnetic taconite is an intimate association of magnetite and a siliceous gangue. It must be ground to approximately 70 to 30 percent minus 325 mesh to liberate the magnetite from the gangue. With sufficient liberation, magnetic concentration will yield a product high enough in iron and low enough in silica for blast-furnace use. The magnetic concentrate must be agglomerated before it can be used in a blast furnace. Agglomeration is the general term applied to all methods of compacting or consolidating fine iron-oxide materials, sintering and pelletizing being the two most common methods. Sintering is clone on a Dwight-Lloyd or Greenawalt sintering machine. Pelletizing consists of balling fine, moist oxide in a rotating drum, followed by baking at .a temperature below that of incipient fusion to develop a permanent bond within each pellet. The magnetic concentrate from taconite is too fine for good sintering practice but fine enough for good pelletizing practice.

Jan 1, 1950

By Ronald D. Hill, Elmore C. Grim

To better appreciate the problems associated with surface mining, it 1s imperative that the stripping operation be understood. Surface mining is a very broad term and refers to any process of removing the earth, rock, and other strata in order to uncover the underlying mineral or fuel deposit. Strip mining is a type of surface mining in which the overburden is removed in narrow bands, one cut at a time. Strip mining methods employed to recover coal can be divided into two general types: area and contour.

Jan 1, 1974

By S. M. Molloy

The postwar demand for insulating material such as mineral wool, in-creased in proportion to the rapid construction of new buildings, placing an enormous burden on the existing mineral-wool industry both in known sources of raw materials and in available plant facilities. In view of the increased demand on the industry, the Bureau of Mines in its Mississippi Valley Experiment Station" Rolla, Mo., undertook an investigation to aid the industry by establishing resources of raw materials through actual laboratory wool-blowing tests and by developing certain methods for evaluating the physical proper-ties of a mineral wool. As material was received from the public, laboratory-evaluation technique had to be developed, the results of which would reflect in the mineral-wool-industry standards. The methods of testing used by the mineral-wool industry, not only would have required a pilot-plant installation capable of producing a large tonnage of mineral wool, but each wool-blowing campaign would have been very expensive and necessitated considerable personnel and equipment. The present laboratory wool-blowing equipment can produce as high as eight wool-blowing campaigns a day. The nature, simplicity, and size of the physical testing equipment permit testing as small a sample of wool as 25 grams and give information as reasonably accurate as in a 40-pound bag of wool. The purpose of this report is to describe the laboratory method of production and the evaluation of the physical properties of small quantities of mineral wool. Considerable work has already been done, and the interest of the public and industry is measured in the number of samples being submitted for testing.

Jan 1, 1948

By E. D. Gardner

This paper is one of a series on mining methods and costs being published by the United States Bureau of Mines. In April 19.74 the St. Joseph Lead Co., at Atlanta, Elmore County, Idaho, was mining and milling about 225 tons of gold ore daily with a total force of 150 men. The mine, which comprises the old Boise-Rochester and Monarch properties, is at an elevation of about 6,000 feet. Snow lies on the ground about 5 months each year but does net interfere greatly with local operations. However, the road to Mountain Home, the shipping point 80 miles distant, passes over a high range and usually is closed by snow from about November 15 to June 15. Heavy supplies are brought in and concentrates trucked out during the summer. In winter the district is served by a biweekly mail plane and a passenger and express plane making 4 to 6 trips weekly. Mine timber is cut locally. A plentiful supply of water is obtained from a stream brought to the property through 7,500 feet of plume.

Jan 1, 1935

By Walter E. Lewis

Ventilation-air-heating plants are in use at several iron mines on the Menominee Iron Range, Iron River, Mich. Many of the mines are exceptionally wet; during winter months, when fresh air is forced down the wet air shafts into the mine, it is usually necessary to heat the fresh air to above freezing so that the openings will not be closed by ice. The problem of ice closing air shafts has been solved by the practice of reversing the air current before the openings have become completely closed. This procedure involves drawing warm air from the mine up the usual down-draft air shaft. The M. A. Hanna Co. has found, at some of their mines on the Menominee Range, that it is more convenient to heat the below-freezing air rather than reverse the air current. Intermittent freezing and thawing of ice that has formed in the air shaft tends to loosen the wall rock, requiring major shaft repairs. The openings are kept free of ice the year around by heating the fresh air during periods of below-freezing weather. Table 1 shows the monthly minimum moan, maximum mean, and mean temperatures for the Iron River area. Under normal conditions of temperature, the furnaces are fired in November and usually are not allowed to go out until April of the following year.

Jan 1, 1951

By Jr. Kauffman

The data contained in this report were obtained incidental to the Bureau of Mine's investigation of the lime-soda sinter process as applied to the recovery of alumina from siliceous bauxite, kaolin, and other high aluminous materials. The Bureau of Mines was charged by Congress to investigate processes for the production of aluminum from domestic low-grade ores. The Eastern Experiment Station at College Park, Md., conducted laboratory and pilot-plant investigations of the recover-y of alumina by the lime-soda sinter process. Reports by the College Park staff covering the recovery of alumina from these sources have been published. The lime-soda sinter process involves the sintering of the finely ground siliceous bauxite or clay with limestone and soda ash in a rotary kiln. During the sintering the alumina supposedly reacts with the soda ash to form soluble sodium aluminate and the silica combines with the lime to form the insoluble orthosilicate. In the early stages of the investigation it was considered desirable to know the temperatures at which the phase changes occurred during the sintering operation. The total time involved in the passage of any given portion of the charge through the kiln was 28 minutes. The exposure time of the charge to temperatures above 600° C. (decomposition temperature of kaolinite) was, roughly, half the total. The exposure to the full temperature of the kiln, 1,100° C was only 3 minutes. (Subsequently, the maximum kiln temperature and retention time were increased.)

Jan 1, 1949

By K. Robert Dorman

This Bureau of Mines report describes laboratory and field experimentation in building mine ventilation stoppings, air-door frames, and fan bulkheads with a civil construction technique. Shotcrete is applied to a free-standing, three-dimensional wire-truss panel, which is easily cut and rapidly erected. In mines where shotcrete equipment is available, this technique should be faster and cheaper than conventional block-and-mortar or monolithic concrete construction.

Jan 1, 1980

By J. K. Richmond

Early research on coal dust explosions by the Federal Bureau of Mines and in other countries is reviewed to examine the effect of a single inhibitor, rock dust, on the explosion limits of coal dust. The parameters studied in this research included coal dust fineness, volatile content, and type of initiation. This research resulted in appropriate safety regulations in the respective countries. Also reported are the results of recent research in the Experimental Mine of the Bureau of Mines to investigate in detail the limits of coal dust explosions; the research used three types of coal with rock dust added as the independent variable. New experimental techniques and new criteria for defining propagation/nonpropagation were applied to the experiments. Also, a limit explosion propagation model is proposed based on the assumption of rapid devolatilization of the coal particles, with the subsequent combustion of the evolved volatile products contributing primarily to the propagation of the explosions. The model assumes also that the resultant char acts mainly as an inert diluent similar to the rock dust. The model also suggests that the function of stronger initiation is mostly to lift more dust from the mine surfaces.

Jan 1, 1975

By Thomas G. Carnahan

The Bureau of Mines conducted research to simulate in situ leaching of a chalcopyrite ore. The purpose was to obtain a direct comparison between moderate-temperature and elevated-temperature in situ leaching of copper trom minus la-inch ore and to analyze the sulfuric acid and oxygen requirements of the leaching system. Experiments employing oxygen were conducted at 35° and 90° C on 362-and 367-1b ore charges, respectively, under flooded conditions and at 400 psig. At 90° C, 47 pct of the copper was extracted in 913 days of leaching; at 35° C, 27 pct of the copper was extracted in 915 days. Diffusion into and out of the ore fragments con-trolled the rate of leaching. Oxygen consumption was 1.46 lb/lb of copper extracted at 35° C and 3.15 lb/lb of copper extracted at 90° C. Sulfuric acid requirements of the ore were 5.49 and 7.48 lb/lb of copper extracted at 35° and 90° C, respectively.

Jan 1, 1982

By Joseph W. Martin

The Bureau of Mines investigated the backscattering of low-energy gamma rays as a method for rapidly determining the incombustible content of coal mine dust. In this method, 60-kev gamma rays from americium-24l penetrate the dust and are reflected by elements in the dust to a thin crystal scintillation detector. The number of backscattered gamma rays is proportional to the incombustible content. Tests of 40 dry, mine-dust samples containing 50 to 100 percent inert material show an average error of 2 percent. Calibration of the apparatus is necessary for each rock dust to account for variable composition. Results for samples containing more than 6 percent moisture are subject to error, but the values are lower than values obtained by chemical analysis, and thus fall on the safe side. Development of a small portable meter based on the backscatter principle appears feasible. Such a meter would find application within coal mines to check the effectiveness of rock dusting procedures.

Jan 1, 1968

By Richard A. Watson, James A. Powell

A seismic system which utilizes in-mine geophones to detect trapped miners has been developed. Tests at the Bureau of Mines Safety Research Mine at Bruceton, Pa., and at two operating mines indicate such a system has a maximum detection range in excess of 1,000 feet. The system is field worthy and portable and requires less than 30 minutes to set up and check. Real-time detection is possible.

Jan 1, 1976

By J. A. Eisele

The Bureau of Hines conducted a bench-scale investigation of a concentrated H2S04 reaction for recovering and separating rare-earth elements, barium, and strontium from a bastnasite ore and byproduct. Barium and strontium were dissolved in the concentrated acid and precipitated as a mixed product by water dilution. Separation of strontium from barium was effected by reaction with Na2C03 solution, followed by a dilute acid leach of the SrC03 formed. After removing the barium and strontium from bastnäsite are, the rare-earth elements were roasted to water-soluble sulfates. The rare-earth sulfate solution was subsequently processed by solvent extraction to produce rare-earth oxides low in lead and magnesium.

Jan 1, 1974

By George S. Rice, J. W. Paul, E. H. Denny

Data assembled by the Bureau of Mines , coupled with requests from coal companies , have emphasized the desirability of establishing standardized specifications for brattice cloth with particular respect to durability and fireproofing . Brattice cloth is a canvas or other material , often covered with some fireproofing composition , which is used extensively in coal mining for temporarily deflecting air into pillar workings and maintaining ventilation at the working faces . These specifications will be established , it is planned , through a cooperative program in which the U. S. Bureau of Standards will make a series of tests of various brattice cloths treated with respect to fire- resisting qualities and the U. S. Bureau of Mines will continue to assemble field data on the use of brattice cloth . Plans now are being made for this cooperative work. Without attempting to make a complete survey , the Bureau of Mines has made preliminary studies and investigations , and verious representative coal - mining companies have furnished detailed information . The information thus gained will be used as the basis for the cooperative investigation , but the Bureau of Mines would welcome additional information from mine operators on the character and weight of brattice cloth , conditions of use , durability , quantity employed and price . Such information should be sent to the Director , Bureau of Mines , Washington , D. C. The mine operator is interested in procuring at reasonable cost a brattice cloth with lasting fireproofing quality and of as great durability and strength as possible . There has been a lack of assembled data and knowledge regarding the subject , but the Bureau of Mines feels that this lack of knowledge may be overcome if the coal -mining companies will lend their hearty support to the cooperative investigation and submit information relative to the use of brattice cloth in their own properties . Information contained in this report is based on data obtained from coal operators in bituminous districts of Pennsylvania , Alabama , Utah , Indiana , Illinois , Colorado and Nova Scotia .

Feb 1, 1923

By T. L. Joseph

The purpose of this article is to describe briefly the operation of a 6-ton blast furnace on a charge of bauxite, limestone, iron ore, and cast-iron turnings and to point out the bearing which smelting such a charge has upon the production of alumina cement. One object of the experiment, conducted by the Bureau of Mines in cooperation with the Aluminum Co. of America, was to determine whether tae so-called Pedersen process3 can be applied to the blast furnace. This process consists of smelting a charge of bauxite, iron ore, and. limestone, and results in to products. One is a slag containing about 50 per cent of A1203 and is intended for use in manufacturing aluminum, and the other is iron low in sulphur. Complete details of the test are published in other reports4. Blast-furnace slag is now recognized as a satisfactory and economical raw material for making Portland cement, Wm. A. Forbes5 has recently reported that in 1926 an important steel interest used well over 1 million tons of slag in producing about 24 million long, tons of cement. This is equivalent to about ½ ton of slag for each ton of cement. Alumina cement can be made direct in the blast furnace. Its physical character would have to be changed by grinding, but no change in its chemical composition would be necessary.

Jan 1, 1928

By L. C. IlsLey, R. A. Kearns

As the use of electricity becomes more and more general in mining opera- tions, interest in regulations governing its application becomes greater. During the past year the electrical section of the Bureau of Mines has made a study of State regulations now in force relating to the use of electricity in coal mines. Technical Paper 271, entitled "State Mining Laws on the Use of Electricity in and about Coal Mines", has been published as a result of this study. The present paper represents a compilation of all laws relating to accident prevention with respect to electrical circuits. This group of regulations is perhaps the most important of any that relate to safety in coal mines. Its importance is shown by reference to accident statistics in Bulletin 115, (Fay, A.H., Coal-Mine Fatalities in United States, 1870-1914, Bureau of Mines, 1916), which show that about 77 per cent of the fatalities due to electricity in and about coal mines were caused by direct or indirect contact with trolley or other power circuits. In actual number this means that of 710 men killed by electricity, 546 were killed by contact with electric wires. Undoubtedly, a large percentage of these accidents might have been prevented had the wires been properly guarded. The compilation follows:

Mar 1, 1921

By Stephen D. Cramer

The solubility of methane, carbon dioxide, and oxygen was measured in brines at temperatures from 0° to 300° as part of Federal Bureau of Mines research on the corrosion of metals in high-temperature geothermal and mineral processing environments. Solubilities were measured by the technique of extracting pure gas, dissolved at pressures where Henry's law was applicable, from known volumes of brine. The results were smoothed with respect to temperature. The solubility, expressed in terms of the Henry's law constant, reaches a maximum at temperatures ranging from 60° to 100° C for methane and oxygen, and from 160° to 170° C for carbon dioxide. The Henry's law constant increases, that is, gases are salted out of the brines, in the presence of dissolved salts. Salting-out coefficients are strongly dependent upon temperature. The temperature dependence of the Henry's law constant for geothermal brines is different from that for sodium chloride brines owing to the more complex chemistry of the geothermal brines. The solubility of oxygen and carbon dioxide in brines exposed to air saturated with water vapor and at a total pressure of 760 mm Hg is reported for temperatures from 0° C to the normal boiling point.

Jan 1, 1982