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By J. T. McCartney

In an effort to correlate the size of pyrite particles in coal and coal-particle association with the removal of pyrite before burning, the Bureau of Mines conducted a study of 61 coals presently being used for electric power production. The results were obtained by visual microscopic studies of polished briquets of minus l4-mesh samples. Mean pyrite particle sizes ranged from 20 to 400 microns and proportions of pyrite contained in coal particles to an extent greater than 50 percent by volume (estimated) ranged from 20 to 95 percent. These parameters were correlated with reductions in pyrite accomplished by float-sink tests at 1.60 sp gr on 14-mesh, 3/8-inch, and 1-1/2-inch samples. The correlation coefficients between pyrite removal and mean pyrite particle size were 0.89, 0.84, and 0.79, respectively, for these samples. Correlation coefficients between pyrite removal and coal-pyrite association parameter were 0.92, 0090, and 0.85, respectively. It is apparent that extent of pyrite removal can be fairly well predicted from microscopic analysis.

Jan 1, 1969

Minimize drilling time in roof bolting. Approach The Bureau of Mines conducted a survey of 34 roof bolting machines used in underground coal mines. Results of the survey indicated that drilling time, bit cost, and respirable dust concentrations and be reduced by using the appropriate bits for drilling, To evaluate bits currently used and to find optimum cutting parameters needed to minimize drilling time, the Bureau tested two bits commonly used in most underground mines on both wet and dry systems. These are the dusthog* and shank type. The dusthog has dust ports in the bit body to remove cuttings. With shank bits, holes in the drill steel do this. Cost of each type is roughly equal. Bolters with dry vacuum systems were tested in the laboratory first. The lab tests were verified by underground tests in several mines. Bolters with low-pressure wet drilling systems were also tested under-ground. Tests concentrated on the effect of rpm, water and airflow rates, heating, wear, bit design and bit type. Lab Results -Dry Drilling Holes were drilled during the laboratory tests using a production model bolter drilling 45-inch-deep holes into mixtures of lime stone and sandstone aggregate. All tests started with new shank and dusthog type bits at 225 and 450 rpm. Thrust was about 6,000 lbs in all tests. Each bit was tested at two airflows, 15 and 25 cfm, airflows which are typical on operating roof bolter bits. Eleven styles of bits were evaluated. On the average, dusthog bits drilled 25% faster than shank types and were always cooler after drilling. The effect of RPM was tested with 5 different bit types. When bit rpm was increased from 300 to 400, drilling rates doubled. With used, well-worn bits drilling time and final bit temperature were more than doubled.

Jan 1, 1986

By Thomas M. Barczak

This U.S. Bureau of Mines study evaluates factors that influence longwall support and strata interaction. The longwall system is composed of an immediate and main roof structure and three supporting foundations: longwall panel, powered roof supports, and gob waste. The main roof forms a structure that is generally supported by all three foundations, while the immediate roof acts as a beam that cantilevers from the coal face to the powered support. In most cases, shield loading involves a complex interaction of both main roof and immediate roof behavior and is a combination of loads produced from convergence of the main roof and displacements of the immediate roof caused by deformations of the cantilevered roof beam. Since the shield stiffness remains constant for all leg pressures and main roof convergence is irresistible in terms of shield capacity, the shield must be able to control the behavior of the immediate roof or floor structure for shield loading to be sensitive to setting pressures. If the goal is to minimize total shield loading, any active setting force must be offset by reduced passive shield loading to justify the active setting loads. Field data sumest that the typical reductions in passive loading do not justify the required increases in setting pressure in some applications.

Jan 1, 2010

By L. H. Duschak

"This paper is based on the results of work conducted of the bureau's experiment station at Berkeley, Calif., in connection with the investigation of properties and methods of utilizing Western magnesite. The experiments described herein were made under the supervision of the writer, by W. C. Riddell and E. H. Delius, of the station's staff.In calcining magnesite for the production of magnesium oxide to be used in the preparation of oxychloride cement, the calcium carbonate present in the original rock may remain unchanged or appear in the finished product, either as CaO, or in combination with SiO2, A12O3, etc. As there is reason to believe that free CaO may have an effect on the behavior of caustic magnesia in the cement reaction, it is desirable to have a method for the determination of the relatively small amounts of free CO in the presence of a large quantity of MgO.The extraction of the free CaO with water free from CO2 at once suggests itself as a possible method. The solubilities of Ca(OH2)2 and Mg(OH)2. are given by Seidell in his book an ""Solubility of Inorganic and Organic Compounds."" (2nd Edition, 1919) as follows:"

Jun 1, 1920

1. In 2002, a total of 4,311 stone mining operations reported employment to the Mine Safety and Health Administration (MSHA). The major industrial classifications in stone mining are dimension stone (used for construction purposes), crushed and broken stone (aggregates), cement, and lime. Stone mines comprised 29.7% of all mining operations. • Mines producing crushed and broken stone (n = 3,372) comprised 78.2% of all stone mining operations.

Jan 1, 2004

By A. J. Kraemer, O. C. Blade

This report on the properties of motor fuels sold through service stations in the United States is a continuation of a series of reports made in accordance with a cooperative agreement between the Coordinating Fuel Research (C. F. R. ) Committee of the Coordinating Research Council (C. R. C.) and the Bureau of Mines of the United States Department of the Interior . The first of these reports contained data on motor gasolines sold during the winter of 1935-36 and further reports on motor gasolines sold during the succeeding summers and winters to the summer of 1941

Dec 1, 1943

By Miles B. Royert

Crude Minnesota taconite was charged in the Bureau of Mines experimental blast furnace so that smelting characteristics of such highly siliceous raw materials could be studied and smelting costs compared with those of a standard Mesabi ore. The Bureau recognized that the highly siliceous nature of the crude ore and its relatively low metallic content would be serious economic deterrents to commercial use of the raw taconite, but compensating factors would be low capital investment in production facilities, large tonnage available on short notice, high recoveries of iron, and low delivered cost. Crude taconite smelted readily in the experimental blast furnace. Coke consumption per ton of metallic product was very high, compared with the average established requirements for smelting normal grades of metalliferous raw materials. Slag rates were also inordinately high. Metal quality was erratic as to silicon, and sulfur contents were objectionably high.

Jan 1, 1961

By R. G. Meara, O&apos

The land-pebble district of Florida, wnich in 1928 supplied 96.7 per cent of the phosphate production of that State and 82 per cent of the domestic requirements of the United States, is centered in Polk and Hillsboro Counties about 30 miles east of Tampa The deposits are unconsolidated sediments occurring as beds of phosphate matrix overlain by a mantle of barren sands and clays. The matrix consists of a mixture of sand (quartz grains), clay, and phosphate rock in which the coarsest sand is much finer than the coarsest phosphate; that is, the sand is segregated in the fine material. Before the introduction of classifiers the concentration consisted of log washing, and screening at about 20-mesh, which was usually the finest size that could be taken to maintain commercial grade, 66 per cent B. P. L. (bone phosphate of lime) or more. When classifiers were introduced some of the fines that had escaped at the head of the washery and some of the minus 20-mesh material isolated during the washing and formerly lost supplied the feed. During October, 1927, the United States Bureau of Mines in cooperation with the University of Alabama and the Missouri School of Mines and Metallurgy began to investigate the amenability of phosphatic sands to gravity methods of concentration. The work was under the immediate supervision of B. W. Gandrud, acting supervising engineer of the Southern Experiment Station of the U. S. Bureau of Mines at Tuscaloosa, Ala., and Will H. Coghill, supervising engineer of the ore dressing section of the U. S. Bureau of Mines. More comprehensive testing followed and in the early part of 1930 some of the companies cooperated with the bureau and the above-mentioned institutions in conducting a series of tests on hydraulic classification and tabling. The results indicated that marketable concentrates could be obtained with a recovery of 25 to 45 per cent of the phosphate formerly lost. As a result two companies have introduced hydraulic classification to treat the current tailings, and one of them has substituted classifiers for the 20-mesh screens which had been unsatisfactory. Because the phosphate grains and quartz grains have nearly the same specific gravity, the use of concentrating tables by the customary methods is not applicable. The washeries included in the following report are designated as Nos. 1, 2, and 3.

Jan 1, 1931

By B. J. Dalton

The Bureau of Mines Helium Research Center has as a long-range objective the development of an equation of state for helium that will allow all of the thermodynamic properties to be calculated within the accuracy with which they are known. If this objective is to be realized, a method of calculation must be known. This report gives the principles of the method we use in such problems. A computer program was developed for predicting these properties, including those at the critical point, that is perfectly general and applicable to any equation of state. To demonstrate the efficacy of our method, this computer program was used to evaluate thermodynamic properties of a Redlich-Kwong fluid in the two-phase region. Expressions for calculating various thermodynamic functions specific for this particular equation of state are derived. Numerical values are tabulated and graphs are presented for all functions calculated. It is shown that for a Redlich-Kwong fluid there are finite discontinuities in (1) the second temperature derivative of the Gibbs free energy or chemical potential at the critical point, (2) the second derivative of the vapor pressure curve with regard to the temperature on passing through the critical point, and (3) the measured heat capacity at constant volume on passing through the critical temperature when the calorimeter is filled to the critical density. It is also shown that the heat of vaporization is infinite for a Redlich-Kwong fluid at absolute zero.

Jan 1, 1969

By J. A. Woolf, E. S. Leaver

"So much has been written on the ore genesis of the Comstock Lode that it is sufficient here to describe the original ores as consisting chiefly of quartz and some calcite. In places .a considerable amount of pyrite appears. There are also minor amounts of galena, chalcopyrite, and sphalerite. The chief silver minerals are argentite, stephanite, and polybasite. Most of the gold is native.A composite analysis of the ore; obtained by averaging the results from the early workings of several mines, is shown in Table 1.The history of the milling of Comstock ores from the Sixties to date would call for a review of the development of precious-metal metallurgy. However, a brief outline of the methods employed will give a better basis for studying the difficulties that are to be expected in the final retreatment of the remaining residues.In the earliest days amalgamation was accepted as the main recovery method. The large tonnage of good-grade ore from the Comstock Lode attracted the best metal¬lurgical talent of the time, and developed there the highest skill in the art of amalgamation, including the auxiliary chemical preparation of the ores and the mechanical operation. In this work 0.5 to 6.0 pounds of mercury was used per ton of ore. The mercury loss probably averaged about 2.5 pounds per ton of ore treated.The better grade of tailings from the ores milled were impounded, often near the works. In many cases the same tailings were reworked several times before they entered the main outflow waste stream that had its course down Seven Mile Canyon to the Carson River. Following the water course down the canyon the tailings were re-impounded, and, as metallurgy advanced, new plants were erected to again re-treat them. The most successful of these plants used forms of amalgamation, chlorination, and cyanide methods of recovery. To the tailings from the re-treatment plants, smaller tonnages of untreated tailings produced by milling lower-grade ore are continually added.Along the stream bed down the canyon a series of blanket runways were constructed, and each was independently operated for years by one or more men. All, or the heavier portion of the stream flow was run over the blankets; in this way much of the heavier concentrate, mostly sulphides and mercury products, was reclaimed.All of the residues finally entered the run-off flow along with the sewage from Virginia City and waste from the gas works, saw mills, and stables. As the accumulation along the bed of the Carson River became a nuisance, the lighter and better grade of tailings was impounded on the banks of the river. This accounts for the large dumps locally known as ""Douglas tailings."""

Jul 1, 1928

By O. C. Blade

This report on the properties of motor fuels sold through service stations in the United States is a continuation of a series of reports made in accordance with a cooperative agreement between the Coordinating Fuel Research ( C.F.R. ) Committee of the Coordinating Research Council ( C.R.C. ) and the Bureau of lines of the United States Department of the Interior . The first of these reports presented data on motor gasolines sold during the winter of 1935-35.4/ Further reports have been issued describing motor gasolines sold during the succeeding summers and winters to and including the summer of 1941.5/ No reports were made on motor gasolines sold during the winter of 1941-42 and during the summer of 1942 . However , starting with the winter of 1942-43 , the semi - annual reports have been resumed

Jan 1, 1945

By Wm. W. Odell

For a number of years there has been a very appreciable annual,, increase in the production and recovery of natural gas and natural-gas gasoline2 in the United States the latter product being used largely for blending with gasoline from petroleum in the production of motor fuel. On account of the increased amount of oil cracking in the production of gasoline and the accompanying increased percentage of low-boiling constituents in the resulting product, the specifications for the natural gasoline suitable for blending have been altered, that is, the amounts of propane and butane which it can contain have been limited. The result has been that large quantities of the latter materials are wasted because there has been no ready market for thorn in large quantities. Because of this wasteage and because it is probable that large quantities of there and similar materials will be produced in the near future us a result of the more general use of oil cracking processes, a study was made by the Bureau of Mines, under a cooperative agreement with the assistance of the Phillips Petroleum Company, of the suitability of these materials alone or in mixtures for use as gas enricher in the carburetion of water gas for city distribution. This investigation included: (a) A study of the properties of the low boiling members of the paraffin series including pentane with particular reference to their utilization as gases.

Jan 1, 1927

By F. Fraas, H. H. Storch

"In the second paper 4 of this series, data were presented concerning the decomposi¬tion of polyhalite by saturated salt solutions. It was found that uncalcined polyhalite upon leaching with boiling saturated sodium chloride solutions yielded a brine in which the (K2 Mg) /304 ratio was considerably higher than that obtained from the calcined material, and for this reason appeared more suitable for the production of potassium chloride. It was found, in fact, that the leach liquors from uncalcined polyhalite deposited a mixture of KC1 and NaC1 upon evaporation and subsequent cooling, whereas those from calcined polyhalite yielded mixtures which contained not only potassium and sodium chlorides but also large quantities of glaserite, K3Na (S04)2. Hence it was decided to study the evaporation of the uncalcined poly—halite leach liquor and postpone experiments on the calcined polyhalite liquors until such time as a process for further removal of sulphate was developed.A considerable body of equilibrium data is available in the literature on thesystem K+ Mg++ — Na+ Cl—S04 =,— H20 for temperatures up to 83º C. Owing, however, tothe lack of data other than that corresponding to the invariant points and the complete absence of data for temperatures of 100 to 115°C., and owing to the fact that supersaturation phenomena render unsafe the prediction of the behavior of such a system upon evaporation, it was considered essential to obtain the necessary data by actual evaporation and analysis of the brines thus obtained."

Feb 1, 1931

By Robert C. Steckley

The Bureau of Mines performed a fragmentation experiment in cooperation with Duval Corporation in a porphyry copper-molybdenum deposit near the Sierrita pit south of Tucson, Ariz. This experiment evaluated the fragmentation created in a 10-hole test blast having blasthole spacings of 25, 20, and 15 feet. The 10 blastholes were 9 inches in diameter and contained a total of 17,400 pounds of aluminized slurry blasting agent in 50-foot columns with 60 feet of stemming. Diamond drill core examination was the primary method used to determine the condition of the rock before and after blasting. These core examinations included study of length recovery, rock quality designation (RQD), weight recovery, and size distribution. Topographic surveys were used to measure the rock swell produced by the blast and a fragment size distribution was obtained for the broken material on the surface. Fragmentation to depths of 110 feet was excellent from the 15-to 20-foot blasthole spacing patterns. Good breakage was also produced by the 25-foot pattern although the effects of the blast were not so obvious. In situ leaching tests were not conducted. However, based only on size consideration, all three blasting patterns produced adequate breakage for successful leaching.

Jan 1, 1975

By R. G. Meara, O&apos

The land-pebble district of Florida, which in 1928 supplied 96.7 per cent of the phosphate production of that State and 82 per cent of the domestic requirements of the United States, is centered in Polk and Hillsboro Counties about 30 miles east of Tampa The deposits are unconsolidated sediments occurring as beds of phosphate matrix overlain by a mantle of barren sands and clays. The matrix consists of a mixture of Sand (quartz grains), clay, and phosphate rock in which the coarsest sand is much finer than the coarsest phosphate; that is, the sand is segregated in the fine material. Before the introduction of classifiers the concentration consisted of log washing, and screening at about 20-mesh, which was usually the finest size that could be taken to maintain commercial grade, 66 per cent B. P. L. (bone phosphate of limey or more. When classifiers were introduced some of the fines that had escaped at the head of the washery and some of the minus 20-mesh material isolated during the rushing and formerly lost supplied the feed.

Jan 1, 1931

By E. G. King

Difficulty has been encountered in making thermodynamic calculations of metallurgical reactions involving interoxidic compounds of the ferroalloy elements because of the serious lack of most thermodynamic data for these substances. This Bureau of Mines report (the first of a planned series dealing with entropies of vanadates, tungstates, and molybdates) presents low-temperature heat-capacity data and entropy values at 298.15° K. for three crystalline sodium vanadates--metavanadate (NaV03), orthovanadate (Na3VO4), and pyro-vanadate (Na4V2O7). The results are combined with data for the constituent oxides and elements to obtain entropies of formation of the vanadates. Previous to this report only one vanadate had been studied Similarly, ammonium metavanadate.4/

Jan 1, 1961

By John Durkin

Owing to the daily exposures of uranium mining personnel to 222Rn daughters, a device is needed that will continually monitor individual exposure. Such a device has been built and tested by the Bureau of Mines and is known as a radon daughter dosimeter. This is an electronic instrument using a solid-state detector and circuitry. The concept of the instrument, which is a personal device worn throughout the working shift, is to evaluate an individual's cumulative exposure to airborne radon progeny, expressed in units of working level hours. Since the instrument is in close proximity to the miner and measures continual exposure, it avoids the errors caused by the present technique of spot checking of the environment and provides a more accurate account of total cumulative exposure.

Jan 1, 1977

"The town of Monson in Piscutaquis County, Maine is the, center of an important site industry. Monson slate has a nation-wide reputation, particularly for electrical switch boards, and the deposits have been worked for the manufacture of such products for many years. Open-pit quarrying is the method most commonly employed in obtaining slate. Underground methods have been used in the Peaon Bottom district near Delta, Pennsylvania, but the quarries that were thus operated are now abandoned. Underground methods have been used more extensively in foreign countries, the most famous example being the slate mines at Angers in France, where an over-head stoping method has been employed successfully for many. It is only under special conditions that underground methods can be successfully used. If the deposit is wide and relatively thin, or if the material is too unsound to constitute a safe roof, open-pit methods must be used, for slate is too low-priced a commodity to justify the heavy expense of any timbering methods. It is only where the deposit is relatively narrow, of great depth, and sufficiently sound to afford a strong roof that ordinary mining may be employed.The best slate beds in two of the three quarries operated at Monson are no worked by underground methods. The chief bed worked by the PortlandMonson Slate Co. is 10 feet thick, stands vertical and strikes N. 63º F. The slaty cleavage is vertical and crosses the strike of the beds at an angle of 5 to 10°. The grain or second direction of splitting is vertical and perpendicular to the cleavage. In addition to the 10-foot bed, to 2-foot beds and one 5-foot bed are available but are not now utilized. In theMonson Maine Slate Co. quarry (the old Pond quarry) a greater number of beds available, but at present quarrying is confined to a single bed about 9 feet thick which dips 30º S.E. and strikes N. 47ºF. The slaty cleavage is vertical and strides N. 45º F., while the grain strikes N. 45-50º W. and is also vertical."

Nov 1, 1920

By T. W. Johnson

The Bureau of Mines, in cooperation with the Natural Gas Department of the American Gas Association, has in progress a study or the flow of natural gas through high-pressure transmission lines. A major problem of this study is to compare the deliveries calculated from the gas pipe-line flow formulas commonly used, with the metered deliveries from pipe lines in operation. In order to obtain such comparisons a series of tests has bean made on 25 operating pipe lines in Kansas, Oklahoma, Louisiana, Arkansas, Texas, and California ACKNOWLEDGEMENTS Study of the flow of natural gas through high-pressure transmission lines was made under the general supervision of H. H. Hill, former chief petroleum engineer of the Bureau of. Mines, H. C. Fowler, acting chief petroleum engineer of the Bureau of Mines, N. A. C. Smith, superintendent of the Bureau of Mines Petroleum Experiment Station at Bartlesville, Okla., and T. Brandenthaler, chief of the oil and gas action of the Bartlesville station.

Jan 1, 1929

By F. R. Lee

This publication lists permissible equipment approved by the Bureau of Mines during 1965 and 1966 (calendar years), except for breathing apparatus and explosives. The purpose of this publication is to inform the public about approved equipment for safe use in underground mines.

Jan 1, 1968