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By James P. Bennett

The U.S. Bureau of Mines investigated the role of imported natural flake graphites in dolomite-carbon refractories used in steelmaking processes and evaluated carbon fibers as a potential substitute. Varying quantities (1.5-30 pct) of natural flake graphite and carbon fibers were added to test samples. The effect of the additions on modulus of rupture (75°-2,750° F), deformation under load (2,750° F), and air-slag-metal resistance (3,000° F) was studied. Carbon purity of natural flake graphite additions did not influence hot strength, deformation under load, or air-slag-metal resistance. When the quantity of 90-pct-carbon graphite addition varied between o and 30 wt pct, hot strength was highest, deformation under load lowest, and air-slag-metal wear the least at 10 wt pct. As test temperature increased from 500° to 2,750° F, the hot strength difference became less. Carbon fiber additions were limited to 1.5 pct in dolomite-carbon brick. At this level, physical properties were generally comparable to those obtained with natural flake graphite, but were below values obtained with 10-pet-f1ake graphite additions. Carbon fibers are not considered a satisfactory substitute for natural flake graphite.

Jan 1, 1989

By D. Harrington

Although for many years considerable attention has been given to devising safe and efficient methods of using explosives, with some success, relatively little has been done to provide satisfactory storage facilities for them. This was known long before the present war began, but it was emphasized during the past 30 months? inspections of explosive magazines by employees of the Bureau of Mines in administration of the Federal Explosives Act of December 26, 1941. These inspections have revealed woeful in adequacy as well as definite hazards and the urgent need for obtaining better storage facilities either by remodeling old magazines or constructing ink new ones that would afford suitable protection for the contents against theft, fire, deterioration, and detonation. The purpose of this paper is to offer suggestions and to show by sketches and drawings some of the fundamental features of suitable magazines. Type of construction and available materials differ with different; localities, but the information herein contained can be applied to most magazines, whether already constructed or the construct: on of which is planned. It is hoped that this information will be helpful and will aid persons who are trying to provide suitable storage for explosives end detonators. It is also hoped that States and cities will be made aware of the unbelievable laxity practiced in storing explosives in the United States and will take some remedial action.

Jan 1, 1945

By Koehler Stout

Previous work done by the authors of this report indicates that hydraulically-placed backfill can be strengthened several fold by various placement methods. Sunshine mill tailings were tested by these placement methods and strength increases up to thirty times were achieved over the ordinary placement methods. A computer simulation study of the test stope in the Sunshine Mine showed that a high-modulus fill absorbs up to 27% of normal stresses versus 7% for "normal" fill while reducing maximum convergence 28% versus 8% for "normal" fill. Although high-modulus fill was not placed in the test stope during this contract, various instrumentation was purchased, designed and built to record necessary data in the stope. Stress gauges were placed in the pillars and recorded data corresponded quite closely with theoretical projections.

Jan 1, 1983

By Margaret M. Ragin

In a cooperative effort between the U.S. Bureau of Mines and the Florida Institute of Phosphate Research, with input from the phosphate industry, the conversion of phosphogypsum to sulfur has been investigated. The first step in the conversion scheme involves reduction of phosphogypsum to calcium sulfide. Effects of temperature, catalyst, reaction time, and type of reductant (carbon monoxide and coal) are discussed. It was determined that phosphogypsum could be reduced to calcium sulfide at 850° to 1,000° C using either coal or carbon monoxide as the reductant. The required temperature was lowered to 750° C using ferric oxide or magnetite as a catalyst for the reduction reaction. Results indicate that as the volatiles content of the coal is increased, reaction temperature may be decreased to obtain a given conversion, or if the reaction temperature is maintained constant, the conversion can be increased. Best results were 95- to 100-pct conversion using a high-volatile coal at 800° to 850° C. Addition of a catalyst increased calcium sulfide yield when low- or medium-volatile coals were used as reductants, but had little effect when high-volatile coals were used.

Jan 1, 1990

Watershed Jll in Jefferson County, Ohio we instrumented in 1977 as one of three watersheds established for the purpose of investigating surface mining and reclamation effects upon local hydrology, sediment discharge, and sediment and water quality. Each watershed was less than 50-acres in size, and was in a different geologic setting within southeastern Ohio. Surface runoff and ground¬water levels were monitored. Samples were taken for sediment determination and chemical analysis prior to mining. Monitoring and sampling continued through the period of watershed disturbance caused by mining and reclamation activities, which began in May 1980 at Watershed Jll. A psuedo-postreclamation period followed the initial cessation of man-machine activity on the watershed. A second reclamation effort occurred in the fall of 1981 and was to be followed by a third in 1982 after observations ceased. A true final postreclamation period was not monitored at this site, because the erosion control practice (terrace diversions) failed after each reclamation. Watershed Jll was a small pasture and wooded watershed with sandstone and shale above the mined coal seam prior to mining. A clay layer under the coal supported a perched saturated zone, termed the top aquifer for convenience. A lower underclay supported a second saturated zone called the middle aquifer. A lower perched aquifer had been dewatered by previous deep mining. After about three years of premine data and about two and one-half years of mining reclamation and psuedo-postreclamation data, the following general observations may be made: 1. The mining-reclamation phase was very short, and the postmining period was characterized by erosion failures and remedial disturbances that kept the watershed condition and size in a state of change. It was impossible to collect sufficient data to confidently characterize the hydrologic-sediment-chemical aspects of the mining period or of a postreclamation period and, most importantly, of the future watershed after its various properties and characteristics have ceased adjusting to its severe disturbance and reconstitution. 2. A seeding of wheat followed by grasses and legumes was not a particularly successful reclamation practice in terms of stabilizing the new soil. Numerous rills and small gullies developed in spite of installed diversions. 3. Storm runoff rates and yields at the watershed outlet increased from the premine, (phase 1) to the mining-reclamation (Phase 2) periods, and remained at or near the Phase 2 level through the postreclamation (Phase 3a) period. 4. The top aquifer changed in physical and chemical character as a result of mining and was becoming reestablished as the project drew to a close; but it is impossible to predict its final configuration or character. 5. Dewatering of the top aquifer resulted in a complete cessation of baseflow because the middle aquifer water table lay below the elevation of the watershed outlet. 6. The top and middle aquifers were merged in one area of the watershed where the upper coal underclay was disturbed. 7. Failure of the diversion terraces and their outlet obscured the effects of the reclamation practice upon sediment concentration and yields. There was little difference in sediment concentrations between Phases 2 and 3a. 8. Drinking water standards were met by surface waters throughout the period of observation except for two samples that exceeded the nitrate-N allowable level of 10 mg/l. 9. In all Phase 3 surface-water samples, iron concentrations were within the limits established by OSM, and manganese concentrations exceeded the regulation level only once. pH fell below the lower regulation level of 6.0 between 10% and 20% of the time. 10. The chemical quality of sediments was generally about the same after reclamation as before mining, with the exception of organic carbon, which decreased.

Jan 1, 1983

By T. E. Gray

This report describes the preparation characteristics of the significant coalbeds in Harrison County, W. Va. It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for the production of metallurgical coke, either as mined or after beneficiation. Over 6.5 million tons of coal was produced in Harrison County, W. Va., in 1958, of which over 3.7 million tons was cleaned mechanically in seven preparation plants. All of the coal cleaned was from the Pittsburgh bed. It has been estimated that more than 1,816 million tons of coal remains in the county in beds 12 inches or more thick. The Pittsburgh and Redstone beds were selected by the Bureau for a study based on current production rates and estimated minable reserves. Sample locations were selected following a study of the literature, conferences with mining engineers and mining company officials in the field, and examination of the available sites. Six samples were collected from the Pittsburgh bed, and three samples came from the Redstone bed, Float-and-sink tests of the samples collected from the Pittsburgh and Redstone beds showed that neither coal could be upgraded to a metallurgical fuel under the standards set up for this study, even after intensive preparation. Finer crushing of the samples moderately increased the yields and slightly reduced both the ash and the sulfur contents in the 1.30-specific-gravity float fractions. Finer crushing slightly decreased the yields in the 1.58-specific-gravity float fractions, whereas it reduced the sulfur content 0.11 percent for the Redstone sample and 0.46 for the Pittsburgh sample.

Jan 1, 1961

By J. R. Thoenen

The objective of this circular is threefold: First, to describe briefly the various modes of occurrence of sand and gravel. Second, to emphasize the need for adequate prospect¬ ing and exploration prior to the expenditure of funds for development and plant construction. Third, to describe various methods of prospecting and exploration and their application to the several modes of occurrence of sand and gravel. Sand and gravel may be found in nearly every county or township in the United States. Commercial deposits, however, are by no means so widespread. The introduction of concrete and the consequent impetus given to consumption of gravel and sand aggregates has seriously depleted deposits in some congested areas. Increasing re¬ strictions in the specification requirements for marketing sands and gravels have further narrowed the economic areas. On the other hand, the combination of increasing transportation costs and decreasing selling prices has forced the decentralization of gravel production. As a result smaller, intermittently operated, and widely scattered portable or semiportable unit plants have been encroaching on the territory formerly supplied from centrally located pits with large tr.atment plants. Generally speaking, the small portable plant can not produce any great variety of ma¬ terials to as exacting specifications nor as economically as the large permanent plant.

Dec 1, 1932

By E. L. Singleton

The electrochemical reduction of aluminum chloride to aluminum was investigated in a closed, two-compartment cell utilizing a molten chloride electrolyte. The externally heated cell was divided into a reduction compartment and a combination AICl3 feed and metal removal compartment. Aluminum was deposited at 700° C on a molten aluminum catbode from a KCI-NaCI-AICI3 electrolyte. The AICl3 content of the electrolyte was replenished by either vapor or solid additions. The chlorine evolved was collected and measured to give a quantitative evaluation of AICl3 reduction. The effects of anode and cathode current densities and AIC13 concentration on anode current efficiencies were studiedo A range of 64 to 84 percent anode current efficiency was obtained with the 25-pound electrolyte capacity cell and related auxiliary equipment.

Jan 1, 1968

By E. G. Davis

Under a memorandum of agreement with Reynolds Metals Co., Richmond, VA, the Bureau of Mines studied the problem of corundum formation on refractory linings in aluminum recycling furnaces. A laboratory test was developed for evaluating refractories in contact with molten recycled aluminum and identifying the mechanism of corundum formation. A test apparatus was designed and constructed to evaluate the performance of refractory samples. Corundum mechanism formation studies indicated that corundum formed on refractories when there is metal penetration. Once corundum forms, it acts as a wick allowing the molten aluminum to move to the surface where it is oxidized, thus causing further growth of the corundum. Phosphoric acid treatment or a spinel mortar coating prevented corundum formation on the 70-and 90-pct-A1203 refractories.

Jan 1, 1988

By R. T. MacMillan

Many bench-scale tests and studies have been conducted in developing and testing a chloride-volatilization procedure Ear treating low-grade manganese ore from the Maple Mountain-Hovey Mountain deposit of Aroostook County, Maine. The ore, averaging 10 to 12 percent Mn, contains manganese in several forms and is resistant to concentration or extraction by usual physical and chemical procedures. Over 90 percent of the manganese, content of the ore has been recovered using a chloridizing roast in which the ore was heated at 950°-9b0' C. in a circulating stream of hydrochloric acid gas. Chlorides of manganese and iron were volatilized and swept to a fume collector, where they were condensed and separated from the [as] stream. Operation of a small, 1-pound-per-hour shaft Furnace produced enough chlorides for studying other factors in an integrated process such as: (1) Conversion of the chlorides to oxides; (2) recovery of HC1 gas of suitable concentration Ear recycling to the chloridizer; and (3) control of the Mn-Fe ratio in the oxide product to produce a suitable feed for ferromanganese production.

Jan 1, 1956

By C. C. Stevenson, Thomas Varley

"The art of treating ores by the chloride volatilization process is still in the experimental stage. The process has not been sufficiently developed along chemical and metallurgical lines to state definitely just what place it will occupy in the metallurgical industry. The theory upon which the process operates has received the attention of prominent metallurgists for the past twenty years, and research and experimental work has been conducted by many investigators.Much of the experimental work done has never been published, and it seems that the accumulation of such results if made known would be an important aid to the further development of the process. The object of this paper is, therefore, to bring salient features of the process to the attention of the metallurgical industry, both for the purpose of furnishing information, and receiving from interested parties any comments which the reading of this article may suggest. A bulletin covering the work done at the Intermountain experiment station of the U. S. Bureau of Mines, situated at Salt Lake City, Utah, is in course of preparation.The chloridizing roast is usually accompanied by appreciable losses due, to the volatilization of the metals as chlorides during the roast, these losses often running as high as 30 per cent, depending upon the temperature, the character of the ores and the associated gangue material. It was not until 1891 that Croasdale, (Croasdale, Stuart, Engineering and Mining Journal, Aug. 29 1903) by observing this and stack deposits from the chloridizing roast, recognized the possibility of making volatilization a major instead of a minor feature of the roast. He then made tests on a large number of tires from different, localities, the result of which showed the, general application of the process. The main difficulty, as stated, by Croasdale, was the lack of a suitable means for recovering the fume from the furnace gasesIn 1913, Cottrell (See Mining and Scientific Press, March 29, 1913; alsoTrans. American Institute of Mining Engineering, September 1918. (Additional informa-tion is available from the owners, The Research Corporation of New lark, and Western Precipitation Co., .Los Angeles, Calif.), announced his invention of the electrostatic precipitator, which solved the problem of separating the solids from the furnace gases."

May 1, 1921

By Welby G. Courtney

The Bureau of Mines conducted an exploratory field survey to determine the amount of airborne coal dust, the size distribution of the dust, and the rate of dust deposition in coal mine airways. The survey was taken at eight underground locations in operating coal mines. The rate of dust deposition in the airways depended upon the concentration of air-borne dust and decreased exponentially with distance from the dust source. The rate was seemingly independent of the size of the airborne dust particles. The rate of deposition, along a return, for the coal dust from a fade being mined with a continuous mining machine closely matched the rate for the rock dust from a trickle duster. A sample rock-dusting schedule for that return is presented; that is, the trickle duster should be operated for 3-112 hours after every five shifts to protect the average deposit of new float coal dust in the return, but operation after every three shifts is preferred, to protect an occasional heavier deposit.

Jan 1, 1982

By S. J. Broderick

"INTRODUCTION Dark soils are commonly believed to be better for agricultural purposes than light-color soils. Much of this feeling may be purely psychological, as many persons have unconsciously acquired the habit of associating richness of soil with color light soils, however, may be just as rich in humus and plant foods as the best of the dark soils. A dis-cussion of the manifold attributes that play an important role in soil technology is beyond the scope of this paper, but the color factor will be considered, as it has a particular bearing on some field experiments using coal-mine waste as a darkening medium.It has been established that dark soils absorb more of the sun's radiation, consequently are maintained at a higher temperature than light soils. This physical principle is applied in our daily lives in the choice of clothing. White clotnes in summer are cooler than dark ones. Conversely, dark clothes in winter are warmer than light-color clothing. A decided advantage of dark soils over light soils is the higher average temperature of the former, resulting in an earlier maturing crop. This advance of the maturing season may range from a few days to a month, depending on such factors as climate, crop, and degree of color of the soil. It has been reported that in parts of Russia where the growing season is short, perhaps comparable to that in Pennsylvania and. New York, cotton has been grown successfully on soils originally of light color, but darkened with coal, dusts. The growth of cotton is, accordingly, speeded up a full month. 3/"

May 1, 1940

By James S. Browning

For the past several years, the Bureau of Mines has conducted laboratory and continuous process development work on weathered mica pegmatites and micaceous schist ores to determine the feasibility of recovering commercial-grade mica concentrates by flotation. The research has resulted in the development of two processes for flotadon of mica: an acid cationic method for recovery of coarse mica, and an alkaline anionic-cationic method for recovery of fine mica. The research indicated that the two processes may be effectively utilized separately or in combination for flotation of mica from weathered pegmatites and micaceous schists. Concentrates containing over 98 percent mica, with recoveries ranging from 77 to 92 percent, were obtained from the pegmatite ores. The micaceous schist ores yielded concentrates containing 95 to 98 percent mica, with recoveries ranging from 70 to 83 percent. Part 1 of this report summarizes the process development work and demonstrates the feasibility of producing commercial- grade mica concentrates. The report also includes details of commercial beneficiation and grinding of .mica.

Jan 1, 1973

By William J. Wuest

This U.S. Bureau of Mines report presents an overview of ground control considerations associated with floor heave. Factors affecting heave, such as in situ stress, floor characteristics, and mine geometry, are described. Floor-displacement monitoring and data analysis methods are outlined. Finally, floor heave remediation is discussed. The remedial techniques are divided into four categories: mine maintenance, supplemental support, mine structure, and techniques for multiple-seam operations. Other subjects covered in the report include laboratory and in-place testing of floor rocks, U.S. and international case studies, effects of mine layout, determination of excess horizontal pressure, and types of heave failure. The emphasis of this report is on practical considerations; theoretical discussions are kept to a minimum.

Jan 1, 1992

By M. P. Youker

USE OF LOW-PRESSURE GAS BURNERS IN OIL- FIELD BOILERS

Feb 1, 1922

By Arthur B. Johnson

The Bureau of Mines investigated the concentration characteristics of high-clay sylvinite ores from four potash companies operating in the Permian Basin near Carlsbad, N. Mex. These ores, containing 13 to 22 percent K20 and 3 to 7 percent clay slimes, cannot be effectively processed by current commercial flotation methods because of their high slime content. A solution to this problem was shown to be the use of two-stage moderate scrubbing conditions and washing of the ore as opposed to strenuous attritioning. Bench-scale physical beneficiation techniques for recovering potash minerals and the development of ore-dressing systems by flotation resulted in obtaining acceptable product grades and recoveries. By using a coarse grind, emphasis was placed on production of premium granular and coarse products. Flotation results showed that concentrates of 58.7 to 60.4 percent K20 with recoveries of 71.0 to 83.4 percent 0f the K20 values can be obtained.

Jan 1, 1971

By John B. Knaebel

This paper is one of a series being prepared by the Bureau of Mines on mining methods and costs at various mines in the United States, Canada, and Mexico, and is a description of practice at the Edwards mine of the St. Joseph Lead Co. ACKNOWLEDGMENTS The cooperation and assistance of the officials of the St. Joseph Lead Co. in permitting publication of this paper and providing every facility for its preparation are gratefully acknowledged. Especial thanks are extended R. J. Mechin, manager, R. F. Mitchell, mine captain, and J. S. Brown, geologist, for their generous aid, and the assistance of W. H, Weijola, mine engineer in assembling some of the illustrations is deeply appreciated, The helpful suggestions of C. F. Jackson, principal mining engineer, U. S. Bureau of Mines, are gratefully acknowledged.

Jan 1, 1932

By Wils L. Cooley

Two major grounding topics are covered: mine ground systems and ground-check monitors. Performance characteristics of ground-check monitors for high-voltage surface mine distribution cables and low-voltage underground mine trailing cables are evaluated. Over 20 commercially available monitors are studied to determine their utility. Several monitoring concepts are incorporated into an unusual monitor design, the prototype of which is described in detail. A comparative study of the effectiveness of several alternate methods of grounding surface mine equipment supports the system currently proposed by MSHA. An instrument design to measure earth voltage gradients is described, as well as an instrument design for measuring the effectiveness of dc haulage current return systems. An extreme analysis is made of techniques for measuring earth resistivity and resistance of safety ground beds. Electrolytic corrosion studies of earth electrodes are reported extensively also.

Jan 1, 1979

By D. R. Tesarik

To ensure the stability ofa tailings pond embankment, the height of the phreatic surface must be kept at or below a safe level. In this investigation, the Bureau of Mines analyzed various horizontal drain designs for tailings embankments to determine their effects on location of the phreatic surface. This report describes the investigation, and it includes 21 dimensionless graphs that can be used to estimate the drain spacing and length dimensions necessary to ensure the stability of embankments of various configurations. Analyses were based on the use of two computer codes, a three-dimensional finite-element code and a two-dimensional finite-difference code. The computer-generated results were compared with results obtained from a laboratory embankment model, other laboratory test results, and piezomet-ric data from two actual tailings embankments. Nearly the same phreatic surface locations were predicted using either of the computer codes. For one of the actual embankments studied, the predicted phreatic surface location was slightly higher than the measured location; for the other, the predicted location closely followed the actual surface trend. Phreatic surfaces of the laboratory model were slightly higher than the code-gener-ated locations, and the differences grew larger as drain length increased or drain spacing decreased.

Jan 1, 1984