Search Documents

By John E. Shelton

Flotation tests were conducted on two samples of copper-nickel-bearing ore from the Harriman area near Rockport, Maine. The samples were taken by Roland F. Beers, Inc., for tests in cooperation with the Federal Bureau of Mines. One sample, analyzing 0.38 percent copper and 0.71 percent nickel, was essentially a disseminated pyrrhotite in hypersthene. Pentlandite, chalcopyrite, pyrite, and millerite were intimately associated with the pyrrhotite. Locked series flotation tests on this sample showed that 87.4 and 73.4 percent of the copper and nickel, respectively, could be recovered in a bulk concentrate that analyzed 3.47 percent copper and 5.34 percent nickel. The copper-and nickel-bearing minerals were collected with sulfhydric collectors in an alkaline circuit. Cleaning the concentrate three times with the addition of pH regulators was sufficient to attain the previously stated grades. The second sample had analyses of 0.31 percent copper and 0.85 percent nickel; talc and hypersthene were the main gangue minerals. Bulk sulfide flotation, made while depressing the talc, resulted in a concentrate that analyzed 2.33 percent copper and 4.70 percent nickel at recoveries of 70.0 and 54.4 percent, respectively. Flotation of the talc followed by bulk sulfide flotation resulted in a nickel content greater than 5 percent. A locked-series test showed that 60.7 percent of the copper and 73.7 percent of the nickel could be recovered at grades of 1.29 and 4.85 percent, respectively.

Jan 1, 1961

By C. Watson Owings

"The mining Industry in the United States is becoming fully cognizant of the hazards of dust in underground mining as well as in surface plants. The dust problem in metal mines has been brought to focus through knowledge of the harmful effects of dust, especially silica, and through adoption of more or less stringent legislation classifying certain types of pneumoconiosis as occupational diseases. The coal-mining industry is aroused principally by the apparently great increase in the dust-explosion hazard resulting from the rapid growth of mechanized mining. The United States Department of the Interior, through the Safety. Division of the Bureau of Mines, has been requested repeatedly to recommend methods of allaying dust in both coal and metal mines. Methods adequate under hand-mining conditions fail to effect satisfactory reduction of dust in more rapid extraction with modern equipment. Studies of methods and equipment for allaying dust are being conducted in both metal and coal mines. Results of these studies are discussed, and indications of possible means of reducing dust concentrations are presented in the hope that the health and 'safety of men employed in the mining industry may be increasingly safeguarded.DUSTThe term ""dust"" is a common one, and yet the meaning is applied to widely different particle sizes. The general term means ""earth or other matter reduced to fine, dry, and powdery particles."" The root from which the word is derived means ""something that can be blown about by the wind."" As a result of tests on the explosibility of coal, the Federal Bureau of Mines has arbitrarily defined dust as being. ""that which will pass through a 20-mesh screen,"" based upon the fact that particles coarser than 20-mesh have little influence on the development of an explosion of Pittsburgh coal-bed dust. The study of dust, from a health standpoint, has given rise to still another definition of dust, namely,- according to Drinker3/, ""solid particles ranging in size from less than 1 micron to about 150 microns."" A micron is 1/25,400 inch, and 150 microns are approximately 1/1,700 inch. Atmospheric dust usually is considered as 10 microns or less, larger particles not being counted under the microscope in determination of dust concentrations."

Apr 1, 1942

By S. J. Gasior

A method for destroying the caking properties of bituminous coal was developed by the Bureau of Mines. Coal is treated in a fixed bed by heating through its plastic range under controlled temperatures in mildly oxidative atmospheres composed of inert gas and/or steam containing about 1 volume-percent oxygen. High-volatile A (hvab) and high-volatile B (hvbb) and low-volatile bituminous (lvb) coals in the size range 1/8 to 1-1/2 inches were successfully treated at 0 (atmospheric pressure) to 300 psig in static beds 6 to 18 inches deep. Conditions of treatment depended on the coal and ranged from 80 to 200 minutes at 350° to 510° C. Char produced in this manner from hvab coal was gasified with steam at 800° C and 100 psig in a fixed bed in one series of tests and in other tests was exposed to hydrogen in a dilute co current free-falling-bed system at 750° C and 3,000 psig without agglomerating.

Jan 1, 1965

By P. H. Floyd

This report presents the results of laboratory beneficiation tests on a sample of scheelite ore and a sample of low-grade scheelite flotation concentrate from the Sangdong mine, Korea. Sangdong was the foremost producer of tungsten concentrates on two occasions - during part of World War II and in 1953. It was also a significant producer of bismuth concentrates. Resources are very extensive and could support a 5,000-ton annual output of tungsten concentrates for many years. Located in the eastern part of South Korea near the 37° latitude, Sangdong has been a vital source of dollar income for the Republic of Korea in recent years. Its shutdown in March 1954 came about as a result of the great decline of tungsten prices and the fact that a sales contract with the United States Government had been terminated, In addition to establishing new markets, the problem of reopening Sangdong will be related to cost reductions and improving mill recoveries. Large quantities of offgrade scheelite concentrates were produced in the past and shipped to the United States for further beneficiation. Other low-grade concentrates and middlings have been stockpiled or discarded at the mine plant.

Jan 1, 1954

By R. Burrell, N .. L. Lapp

"Except for asthma and pulmonary infections, the types of lung disease that have been of immunologic interest the longest are the various mineral pneumoconioses. Because of their chronicity, type of pathology produced, and well-known immunotoxic properties associated with the dusts inciting them, the pneumoconioses have long drawn attention to the possibility that the immune system has not only been modulated but that its effectors have possibly contributed to their pathogenesis. All of the mineral dusts reviewed here have definite immunomodulating properties and act on various cellular and molecular components of the immune system. Further, each has an immunotoxic potential to induce either hypersensitivity (as in the case of beryllium) or other types of immune injury. This article reviews the immunologic aspects of the four major occupational minerals that have an immunologic impact on the lung: asbestos (particularly chrysotile), silica or quartz, beryllium, and coal mine dust.These agents have many things in common, yet each is distinctive. Although the possibility still exists that these mineral particles can adsorb intrinsic tissue antigens or extrinsic organic antigens to their surfaces and initiate immune responses to the adsorbed antigens, only one, beryllium, can act as an antigen itself. Silica is a profound macrophage toxin and thereby exerts many effects on those factors controlled by macrophages. Asbestos has undergone the most immunologic studies resulting in a much dearer picture of how it may contribute to immunopathology. Coal mine dust is the agent about which least is known immunologically, partly because there is no such thing as purified coal mine dust or a standard by which coal mine dust can be defined. Indeed, there are studies that use only the dust from the ground coal itself, whereas other studies use the total dust collected from air samples of a working mine in the belief that other types of dusts (e.g., silica from roof bolt drilling, from sand ground on the rails by cars, and from surface drilling) contribute to the disease (Figs. 1 to 5). This properly is coal mine dust and is poorly characterized. Yet, workers exposed to these dusts share similar reactive characteristics and they may be considered collectively as well as individually."

Mar 1, 1992

By Kevin Ashley

Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate ?lter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (?rst) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air ?lter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards.

Jan 1, 2009

By P. M. Gruzensky

A survey of the literature has been made covering the extraction of bismuth from raw materials, its separation from lead, and its subsequent refining. The use of aqueous, nonaqueous, and fused electrolytes in electrolytic refining is reviewed. This literature survey has been prepared preliminary to some proposed investigations concerning the electrometallurgy of bismuth, and, although an effort has been made to cover a majority of the applicable references, a critical review was not attempted and no assertion is made that this manuscript is exhaustive in nature. Titles of publications in parenthesis are translations from the language in which the reference was originally published.

Jan 1, 1954

By R. E. Heithecker, Van A. Mills

"Crude oils are capable of dissolving quantities of gas under pressure. This fact has been known for some time, but questions have arisen as to the effects of gas in solution upon the characteristics of the oil. Previous investigations4 show that gas in solution in an oil affects the viscosity and surface tension of the oil, but the effects on the volume and A. P. I. gravity of the oil have not been known. The results given in this report show that there is a decided change both in volume and in the A. P. I. gravity of the oil due to the solution of the gas in the oil under pressure. As gas is dissolved, the volume of the oil and the A. P. I. gravity increase. The converse of this phenomenon is also true: if the gas is released from a saturated oil, there is a shrinkage in volume and a decrease in A.P.I. gravity due to the release of gas from solution. However, various oils show marked tendencies to retain a portion of the dissolved gas upon releasing the pressure to that of the atmosphere. This retained gas has an appreciable effect on the volume and A. P. I. gravity of the oil because the oil does not resume its initial volume or gravity while it retains dissolved gas. In a sense the oil has been ""freshened"" and will not return to its original or weathered volume until it loses some of the lighter fractions. Wiggins5 has shown that a fresh oil decreases both in volume and in gravity because of the weathering of the lighter fractions while the oil is standing in storage tanks.This paper includes data attained during the determination of volume and gravity correction factors to be applied in the oil recovery investigations of the Bureau of Mines. Three oils having a wide range in gravity were used in determining the correction factors. These oils were from the Bartlesville-Dewey field, Oklahoma, the Seminole field, Oklahoma, and the Inglewood field, California. The same gas that was used in the oil recovery experiments was used throughout this investigation. Determinations were made of the volume and A.P.I. gravity increases resulting from the gas going into solution at 200, 400, 600, 800, and 1,000 pounds pressure; also the increases in the volume and gravity of the oil due to retained gas were determined after the dissolved gas was liberated from solution by releasing the pressure to that of the atmosphere.Samples of residual and liberated gas were taken throughout the investigation in order to study the selective absorption and selective retention by the oil of the various constituents of the gas. The analyses of these gas samples showed that there was selective absorption and selective retention of the constituents of the gas. The tests on Inglewood crude gave the most pronounced example of selective absorption and selective retention of the gas.All of the tests were conducted at a constant temperature of 709F."

Oct 1, 1928

The first phase of our work for PMSRC on this contract was devoted to a comprehensive and in-depth assessment of electromagnetic (EM) noise measurements and data taken by several contractors for use in the design of operational and emergency mine communications. Pertinent measurements and data of other selected investigators were also included in the evaluation. This assessment treated the measurements and instrumentation used, the data analysis and presentation methods, and the utility of the final results. This phase concluded with the identification of the most useful results and methods, the remaining data gaps, the contractor most qualified to fill these data gaps, and the definition (with PMSRC and this contractor - NBS, National Bureau of Standards) of a follow-on noise measurement program, instrumentation system, and data processing methods tailored to obtain the necessary but missing noise data. A partial bibliography of references related to electromagnetic and seismic noise and propagation in the frequency bands of interest was also compiled during this first phase. The body of this Part of the final report presents a summary of the findings of our EM noise assessment, together with detailed recommendations regarding the new noise measurements to be taken and the instrumentation and data processing methods to be used. This work was done during the latter part of 1971 and the early part of 1972. During subsequent phases of the contract ADL was asked to perform on-going evaluations of the continuing program of electromagnetic (EM) noise and propagation measurements made by Bureau contractors, and to utilize pertinent data from these measurements to make performance estimates for

Jan 1, 1974

By H. R. Shell, Robert C. Johnson, Wilbur H. Warwick

Alpha silicon nitride fibers , Si3N4 , were successfully grown in graphite crucibles by a new method utilizing silicates and silicon ( S in equations below) as sources of silicon and using carbon , aluminum , and silicon as reducing agents (R in equations below ) . The basic reaction mechanism is believed to be generally as follows : 1,300 - 1,500 ° C S + R + N₂ SiO + RO + N₂ › 3Si0 + R + 2N₂ _1,300 - 1,500° C 3RO + Si¸N • ( 1 ) ( 2 ) A build - up of coatings on the solid raw- material particles hindered the evolution of silicon or silicon monoxide vapor and thereby slowed down further formation of silicon nitride fibers . Free oxygen in the crucible caused the formation of amorphous silicon dioxide ( SiO2 ) fibers . This problem was solved by passing , entering , and exiting gases through layers of lump graphite inside the reaction vessel . The silicon nitride fibers grew best around 1,400 ° C. Nitrogen flow rates from 4 to 6 liters per minute were adequate . The fiber widths were generally only a few microns whereas their lengths sometimes reached one - quarter inch or more . Chemical and X- ray analyses indicated that bulk fiber samples were usually 80 to 90 percent Si3N4 . The fibers had good oxidation resistance to about 1,260 ° C. Thermal shock resistance was excellent . Electrical resistance was determined .

Jan 1, 1964

By Albert S. Konselman

This paper describes the mining methods and operating costs for 1938 at the South Burns shaft, situated in the Cripple Creek district, Colorado. The shaft is operated by Golden Conqueror Mines, Inc., through which portions of the properties of the Acacia Cold Mining Co., The Free Coinage Gold Mining Co., and The United Gold Mines Co. are worked under lease. During 1938, 30,773.61 dry tons of ore averaging $9.59 in gold per ton was mined. Of this, 10,138.439 tons averaging $10.65 per ton was produced on company account, and 20,635.171 tons averaging $9.05 per ton was produced by "split-check" lessees.

Jan 1, 1940

By Richard Havens

A flotation procedure was devised by the Federal Bureau of Mines for beneficiating Mount Wheeler, Nev., beryllium ores that contain the beryllium minerals bertrandite and phenacite in a complex association with calcite, fluorspar, mica, quartz, and other accessory minerals, The method also has proven to be effective in trials on ore from the Lake George, Colo., area. Samples used in most of the research ranged from 0.49 to 0.73 percent BeO. Beryllium mineralization varied from two-thirds bertrandite to all phenacite. An unusually high grade sample containing 5 percent BeO as phenacite was floated on a batch basis to prepare concentrate for utilization studies. The beryllium minerals were floated from undeslimed pulps at natural pH using sodium fluoride and sodium hexametaphosphate (HMP), as modifiers, and a fatty acid-fuel oil combination as the collector. Key factors were the use of a minimum of about 4 pounds of sodium fluoride and between 2 and 4 pounds of HMP per ton of ore. Efficacy of the HMP was related to the grind, mineralogical composition, corollary reagents, and type and time of conditioning. Addition of the fluoride, HMP, and collector in that order, followed by appropriate conditioning after each addition, was essential for satisfactory flotation.

Jan 1, 1961

By J. L. Holman

In conjunction with its research program on separation, recovery, and recycling of metal, mineral, and energy-based materials in urban refuse, the U.S. Bureau of Mines is developing means to reuse and recycle plastics discarded in raw municipal waste. Experimental work on plastic waste from a community collection has produced some guidelines for systematic methods of processing, including air classification, cleaning, separation, and use or disposal. Sink-float methods are a practical means of separation into types. Methods for final disposition of the plastic waste include refabrication, thermal decomposition, and incineration.

Jan 1, 1972

By Robert E. Barieau

General expressions for evaluating practically all the thermodynamic properties of a fluid from a single equation of state are derived. Most of the formulas are expressed in terms of the compressibility factor, with this factor being an explicit function of the temperature and the molal density. Similar expressions are given using reduced variables.

Jan 1, 1967

By H. W. Davis, W. W. Adams, O. E. Kiessling

"Current economic problems frequently have focused attention upon the lack of adequate quantitative information indicating the relationship between human effort and output in various branches of the mineral industry. With the exception of complete records covering coal mining, only scattered information on the units of human energy required to produce a unit of raw material is available for most of the important industrial minerals. Fortunately a virtually complete statistical record is available covering this phase of the iron-ore mining industry.For many years iron-ore mining companies, whose interest in safety work is well-known, have reported annual data on employment to be used in the compilation of accident statistics. These data on hours of labor and other detailed employment information have been correlated with the statistics on production also reported annually by producers. The outstanding trends shown by this composite record for the 10-year period 1923-32 are included in the following discussion, supplemented by a summary table that presents the principal statistical background of the study. 5The substantial reduction in the number of men needed to produce the annual iron-ore requirements of the United States, as shown strikingly in the graphs, illustrates that in iron-ore production improvements in technology have been consistently winning a battle over the difficulties of nature. In 1923, for example, 41,294 men working 107,551,244 hours were required to produce 69,351,442 gross tons of merchantable ore, equivalent to an average output of 0.645 ton per man-hour. In 1929, however, only 30,763 men working 77,111,686 hours 'zero required to produce 73,027,720 tons of merchantable ore, equivalent to an average output of 0.947 ton per man-hour. Thus, from 1923 to 1929 the average number of men working decreased 25.5 percent and the total man-hours worked 28.3 percent, while the average output per man-hour increased 46.8 percent and total merchantable ore production 5.3 percent."

Feb 1, 1935

By J. S. Malesky

"INTRODUCTION The Airdox method of breaking coal utilizes compressed air under high pressure and was developed to replace explosives. It is used in Illinois and Indiana mines to a large extent and also has been introduced in mines in a few other States.ACKNOWLEDGMENTThe author gratefully acknowledges the information and photographs furnished by the Cardox Corp.HISTORYIn the early 1920's, with the adoption of mechanical mining in States where on-shift shooting was prohibited, it became desirable to develop some means of breaking coal from the face without the use of explosives. At that time it was thought that a pressure of 20,000 pounds per square inch would be necessary to break the seal. It was impossible to obtain a compressor that would develop this pressure therefore, the 'patentees developed and applied the Cardox method, which utilizes liquid carbon dioxide as the blasting medium."

Aug 1, 1948

By L. B. Berger

Studies showing the effect of mixing hot exhaust gases with the 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 Oliver C. Ralston

The growing popularity of perlite (sometimes spelled pearlite) as a raw material for thermal expansion into pumicelike products in the Western States has prompted a preliminary investigation of the properties of such material and the problems that want solution to put a perlite industry on a firm foundation. The Bureau of Mines is undertaking the gathering of data and the solution of these problems, and the following paper records some of the available information. and the promise of the material, with some comparisons of advantages of the various competing lightweight aggregates that can be made from siliceous volcanic glasses and rocks containing entrapped or dissolved water that causes their expansion on' quick heating to their softening points. This new industrial rock has caught the fancy of the mineral industry in the western States because it has Fume advantages over natural pumice. Chemically, it is typified as rhyolitic in composition, and one may find obsidian, rhyolite, pumice, pumicite, and perlite from the same vant and contemporaneous in origin. The material need not be rhyolite but should be a siliceous or acid lava and contain 2 to 5 percent water still in "solution" in the rock. On quick heating to the softening temperature the material puffs, due to conversion of the contained eater into bubbles of steam. Slow heating causes gradual release of the imprisoned water by decrepitation and. cracking and-results in, very little puffing. Perlite is often in the form of ovoid volcanic bombs formed by explosive eruption of large masses of lava into the air, where they, quickly cool, with escape of little of the contained water, exceptt perhaps for a hollow interior. Since they cool in layers they have an onion-type structure and a pearly luster from interference of light between the. layers, which is' the origin of the name "perlite." Perlite may occur in intruded flows that have been quickly cooled and partly expanded but retained most of their magmatic water content. Obsidian may be the same lava cooled quickly under conditions that prevented crystallization of feldspars and other minerals, leaving the volcanic glass that may or may not retain all of the original contained water.

Jan 1, 1946

By H. P. Greenwald

About mid-December 1936, the safety director of a large coal corporation visited the authors at the Bureau's Experimental coal mine to discuss a rock-dust barrier he had invented primarily for use in trackless entries of coal mines. The rock dust in this device was carried in its original paper containers and means were provided for ripping these open so that the dust might be scattered in the path of an explosion. The inventor termed the device a "bag barrier", and this term has been adopted in the present paper for convenience. At that time the device was in an early stage of development, and the inventor felt that the barrier should be tested to determine whether it had enough promise of being successful to justify further development. The matter was taken under consideration and finally three tests were made during the week of February 15, 1937. It was concluded that while the device did stop an explosion in two of the three tests, it was much loss effective than ordinary rock dusting, and that too few data were obtained to permit direct comparison with tests of other barriers. Apparently, the conditions under which the device could, be successful 'Were somewhat limited, out the limits could not be defined without additional tests.

Jan 1, 1938

By Bill M. Stewart, Phil W. Patton, Curtis C. Clark

Back injuries from handling materials in underground mines continue to be a major safety problem. In spite of the ingenuity of many people and the development of numerous mechanized aids, the number of materials-handling injuries remains second only to the number of roof fall injuries in underground coalmines. Relocation and repositioning of electrical cable, conveyor belt parts, and roof bolt sup-plies in particular are the sources of significant numbers of back injuries. To help reduce such injuries, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are examining Mine Safety and Health Administration accident data to determine correlations between materials-handling tasks and the number of back injuries. Also being investigated are new technologies used in underground mines in the United States. Equipment is being developed or modified that would replace the necessity of doing lifting tasks manually. A Coleman manipulator was tested, and modifications were made to make it more suitable for underground mine use. To reduce or eliminate the need to manually clean off materials that commonly plug grizzly openings, a track-guided pincher arm device was developed. Oversized rock can be broken with the pincher arms in the up position, and the arms can be lowered to grab and remove debris. The arm can also be used in a sweeping action to remove cohesive fines that may bridge grizzly openings.