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By G. E. McElory

"INTRODUCTION The subject of mine and tunnel ventilation has two broad aspects - (1) what atmospheric conditions to obtain in underground openings and (2) how to maintain the desired conditions efficiently. The first relates primarily to quantity requirements of ventilating systems, whereas the second relates more particularly to pressure requirements. Both, therefore, determine power requirements, which is the deciding factor in any system of mine or tunnel ventilation.Both divisions of the subject have received considerable attention from the Bureau of Mines since its inception in 1910 in the form of research, service, and correlation and dissemination of information. Numerous papers on various Phases of the subject have been published, of which a selected list, numbered and arranged in chronological order by type of publication, will be found at the end of this Paper. One of these, Technical Paper 705 (25) 2/ gives a complete bibliography of Bureau of Mines publications dealing with health and safety. As indicated by the selected list of publications accompanying this paper, the health and safety aspects have received most of the attention devoted to this work, chiefly because these have been dominant factors in Bureau policy, but partly because these aspects lend themselves to laboratory research and small-scale field studies. Although considerable attention has also been devoted to the engineering aspects of mine and tunnel ventilation, there has been, in the opinion of the author, who has been engaged on this phase almost continuously for the last 30 years, only sporadic recognition of the vital effect this phase of the work could have on improving health and safety conditions. As a matter of fact, ventilation activities have constituted but a very minor part of the total work of the Bureau of Mines, as, except for a few years in the nineteen twenties, there have been only a few short intervals when more than two or three men were engaged in field work and a similar number in laboratory research directly related to mine gases or mine air."

Mar 1, 1950

By Ernest E. Berger

"INTRODUCTIONOne of the outstanding problems in the normetallic industries, and one which involves two of the greatest of these industries, cement and gypsum, is the reaction of Portland cement with calcium sulphate. To all Portland cement clinker there is added in the manufacturing process, a small amount of retarder, as a necessary ingredient of the finished product. This retards the initial set, increases the strength, and adds to the plasticity of the cement so it will have the desired working and setting qualities. The retarder commonly used is gypsum, (CaSOA.2HO), which is the hydrous form calcium sulphate. Calcium sulphate is also available as plaster of Paris (CaSO4 1/2 HC) and anhydrite (CaSO4). The purpose of this inquiry was to determine the form or mixture of forms best adapted for retarder. The problem is complicated by the fact that cement clinker is a complex mixture of calcium silicates and aluminates, and that clinker from different mills, making cement of approximately equal quality, differs considerably in chemical constitution. Thus the same retarder may give very different results with different types of clinker, especially in the percentage of retarder required for the same degree of retardation.It has been known for some time that a small percentage of plaster of Paris will greatly retard the time of set of Portland cement as well as increase its strength and plasticity, but whether gypsum and anhydrite will have a similar effect is as such disputed question. The offects of gypsum have received little consideration in laboratory research because, even though it will not retard a clinker when the two are mixed in the laboratory, as has been noted in some instances, the cement will have a normal set when the two arc mixed in the large tube mill at the plant, so that practically, gypsum seems to be equally as goou as plaster of Paris, and because of the great saving in cost it has been used almost exclusively."

Sep 1, 1925

By W. W. Adams, E. E. Getzin, T. D. Lawrence

"The thirteenth annual accident-prevention competition conducted by the Bureau of Mines during the calendar year 1937 was completed with 318 mines and quarries participating. This contest, known as the National Safety Competition, is open to all minas and, quarries employing 25 or more men underground or in the quarry or open pit. The entries are divided into five groups to obtain as nearly as possible uniformity of operating conditions and hazards. The five divisions are: (1) Underground anthracite mines, (2) underground bituminous-coal mines, (3) underground metal mines, (4) underground nonmetal mines, (5) quarries and open-pit mines. A bronze trophy, known as Sentinels of Safety, provided by the Explosives Engineer magazine, is awarded to the winner of each group. The trophy is kept by the winning company 1 year and then transferred to the winner of the succeeding year's contest. Certificates of Honorable Mention are given to plants ranking second, third, fourth, and fifth in each group and to all plants operating without a lost-time accident provided the period of exposure to hazard was not less than 30,000 man-hours. Relative standing in the contest is determined by the contestant's accident-severity rate, which represents the total number of days of employee disability from accidents per thousand man-hours worked by all employees.The 1937 contest was outstanding in that the accident-frequency rate for the contest group as a, whole was the lowest on record. Moreover, with one exception 1934, the accident-severity rate was the lowest ever attained: For frequency, 3S.0 accidents per million man-hours worked; and for severity, 8.2 days lost from accidents per thousand man-hours worked. The rates represent a decline of 62 percent in accident frequency since 1925, the first year of the contest, a remarkable accomplishment both for the contest group and for the purpose of the contest because a majority of the contestants have not only participated during the past year but have been enrolled several years, some enrollments even dating back to 1925."

Aug 1, 1938

By J. F. Barkley

"The fly-ash problem of the smoke-abatement engineer - who now might well be titled, ""Smoke and Fly-Ash Abatement Engineer"" - starts with the necessity for him to know what fly ash really is, what plants really create it, and how much is being created. Fly ash in this connection may be defined as all solid particles emitted to the atmosphere as a result of the combustion of fuel.COMPOSITION OF FLY ASHMuch can be learned about fly ash by studying samples with a strong magnifying glass or, preferably, a high-power microscope. As an example, figure 1 is a photomicrograph of an underfeed-stoker fly ash weighing 23.7 pounds per cubic foot, which passed a baffle-type cinder catcher and was caught by a Cottrell precipitator. Figure 2 shows a similar fly ash made at a higher stoker rating and weighing 36.2 pounds per cubic foot. The lighter ash contains more light, unconsolidated ash than the heavier. In both instances some of the ash has been fused to a glass, as is indicated by the spherical particles resembling marbles; however, the heavier dust contains more and larger spheres. With the faster burning and higher air pressures occurring at the higher burning rates, more of the larger fused spheres reached the precipitator.Such studies of fly ash frequently make possible correct determination of its source. For example, the Supreme Court Building, one of the finest of the Federal buildings in Washington, was having considerable difficulty with fly ash from some outside plant. It was thought to come from a nearby apartment house. A fly-ash trap was installed there, and care was taken in the operation of their underfeed stokers. The fly-ash nuisance continued. Microscopic examination of the fly ash found about the building compared with samples taken from the stack of the apartment house showed to the surprise of the accusing building superintendent that the present source was elsewhere. By the same means, the source was found to be a plant about ore-half mile away."

Sep 1, 1939

By Will H. Coghill, I. L. Feld, G. D. Coe

The object of this paper . is to make known the superior classification accomplished in a hydraulic classifier designed to make use of principles determined by recent research ... The details of the design , the results of preliminary research , and the final testing are given . The classifier of the new design shown in figure 1 and another one like it are in operation as concentration classifiers in a Birmingham iron- ore mill recovering 4 tons per hour of concentrates from table middling that ` otherwise would require regrinding and retabling . The four factors that contribute to the successful operation of these classifiers are ( 1 ) a teeter column of small diameter , ( 2 ) use of an open - bottom tooter column classifier with a periodic pincer instead of the usual type , which terminates in a vortex, ( 3 ) a sorting chamber under separate hydraulic control , and ( 4 ) a teeter column of more than the usual depth . · At the outset it must be stated positively what the authors mean by hydraulic classification : They mean the reconstruction of a multimineral ground product into fractions graded with respect to size , so that cach fraction has the heavy mineral segregated in the fine sizes and the light mineral segregated in the coarse sizes . This definition presupposes that in multiplespigot classification the low specific gravity minerals are carried beyond the first cells to the later ones . The reader must take into account that , from the standpoint of classification , " ores " may be divided into two types , represented - by the following : ( 1 ) Joplin flint - blende ores , which , because of the hardness of the flint and the softness of the blonde , yield upon comminution a product that already has the essence of classification ; and ( 2 ) Birmingham Big Seam iron oros , which contain " easily shelled - out " sca sand and , upon reduction to about 10 mesh , yield a heterogeneous mixture in which the size analyses of the respective " floats " and " sinks " arc almost identical .

Dec 1, 1945

By Fei Chen, Lesley J. Gaydos, Laurence M. Demers, Douglas C. Kuhn

The fibrogenic effects of silica in experimental animals and humans has been extensively studied (I 7, 20). However, the pathogenesis and molecular mechanisms underlying lung injury and fibrosis resulting from silica exposure remain to be elucidated. It is well-documented that silica can stimulate monocyte-macrophage lineage cells to produce cytokines and growth factors, including interleukin-I (IL- I) (20), tumor necrosis factor-ex (TNF-cx) (I 7), insulin-like growth factor-I (IGF-1) (4), and transforming growth factor-P (TGF-P) (24). Consequently, it has been suggested that the fibrogenic effect of silica may be mediated by cytokines in the fater stages of silicosis. During the early phase of interaction between silica and the pulmonary alveolar macrophage, several direct and indirect lines of evidence suggest that reactive oxygen intermediates (ROI) may play a pivotal role in silica- induced tissue damage (2I, 22). One of the most important components of and contributors to ROI is nitric oxide (NO) produced from L-arginine and molecular oxygen under the catalytic influence of NO synthase (NOS) (I 9). At present, at least three NOS genes have been cloned: a constitutive neuron NOS, a constitutive endothelial cell NOS and an inducible NOS (iNOS) (16). A number of factors have been shown to differentially induce iNOS gene expression in different cell lines including bacterial cell products and foreign antigens. During inflammation, NO is a double-edged sword in terms of the host immune defense mechanisms and the physiologic response to an inflammatory insult. The macrophage is one of the major cellular sources of NO. During the early phase of acute inflammation, NO produced from the macrophage appears to facilitate the clearance of pathogens and promotes a local relaxation effect on the microcirculation of vascular smooth muscle. When the production of NO is left unattenuated, especially under oxidative stress, direct cytotoxic effects of NO can emerge through the formation of peroxynitrite as a result of a reaction between NO and superoxide (2).

Jan 1, 1998

By D. Eugene Rannels, Sarah E. Dunsmore, Cara Martinez-Williams, Yu-Chen Lee

"Dunsmore, Sarah E., Yu-Chen Lee, Cara Martinez Williams, and D. Eugene Rannels. Synthesis of fibronectin and laminin by type II pulmonary epithelial cells. Am. J. Physiol. 270 (Lung Cell. Mol. Physiol. 14): L215-L223, 1996.Previous investigations demonstrated that type II pulmonary epithelial cells regulate extracellular matrix deposition as a function of time in primary culture. In those studies, the matrix fraction was analyzed as a whole. The present work focused on two components of the type II cell matrix, fibronectin and laminin. These glycoproteins have differing effects on differentiation of type II cells in primary culture. Fibronectin synthesis was quantitated between day 1 and day 6 in the cells, matrix, and medium; laminin synthesis was quantitated only in the cells. Although total fibronectin synthesis was regulated as a function of time in culture, reaching its greatest value on day 2, the average proportion of newly synthesized fibronectin in the cells (35%), medium (50%), and matrix (15%) remained constant over a 6-day interval. Between day 2 and day 6, the relative abundance of fibronectin messenger RNA increased 6.5-fold. Rates of cellular laminin synthesis did not vary with time in culture. These results support a role for differential regulation of fibronectin and laminin synthesis to determine the composition of the type II cell extracellular matrix. INTERACTIONS BETWEEN THE pulmonary epithelium and alveolar basement membrane may play a role in the physiology and pathophysiology of the lung. Pulmonary epithelial cells and the alveolar basement membrane form one component of the blood-gas diffusion barrier. Integrity of this barrier is crucial to normal lung function. Specific domains of alveolar basement membrane components have been proposed to determine localization of type I and type II pulmonary epithelial cells during lung growth and development, as well as during repair of the alveolar surface after injury (13). In the injured lung, the extent of damage to the epithelium and the underlying basement membrane is thought to be a key factor to determine subsequent repair or fibrotic scarring (3)."

Jan 1, 1998

By Donald F. Reed

During the first 6 months of 1948 the Bureau of Mines investigated the titania, deposit on the Wynn 0. Christy property in northern Hot Spring County, Ark. The property is situated in Magnet Cove, about half a mile north of the Magnet Store and U. S. Highway 270 (fig. 1). The purpose of the investigation was to determine the extent and grade of the ore body and to obtain a representative sample of the ore in as nearly natural condition as possible for use in metallurgical testing. All of the titania that has been marketed from Arkansas mines has been in the form of rutile from a deposit about 2 miles west of the Christy property. The titania in the Christy property occurs principally as brookite, which, with fragments of novaculite, quartz, and limonite, is imbedded in red clay. It is difficult to recover a core of the material. Three types of drills - a diamond drill, a bucket drill, and a Baker cable-coring tool operated on a churn rig - were employed in an effort to procure proper samples in their natural state. The Baker tool was found to be the most efficient and to be capable of drilling to a depth of 150 feet, making 80 to 100 percent core recovery (fig. 8). Total footage drilled was 1,536.9 in 21 holes, of which 7 were diamond-drill holes, 13 were bucket drill holes, and one was drilled with the Baker tool. The ore body was found to be 900 feet long, 500 feet wide, and more than 141 feet deep and contained 5.8 percent TiO2 and 0.52 percent 1720. Most of the deeper drill holes bottomed in ore, and there is a possibility that the ore may persist to a depth of several hundred feet. The Metallurgical Division of the Bureau of Mines is conducting experimental work at the Mississippi Valley Experiment Station at Rolla, Mo., for the purpose of developing methods of concntrating and utilizing the ore.

Jan 1, 1949

By Ludwig Schmidt

Large quantities of gasoline are lost each year by evaporation from bulk-storage station tanks. The rate of evaporation from bulk-station tanks is influenced by two principal factors: First, the vapor pressure of the gasoline in the tank; and second, the amount of "breathing" of the tank. The vapor pressures of the gasoline govern the amount of the gasoline vapor in the air-vapor mixture above the gasoline in a tank at a given temperature. This is one of the principal factors in determining the total pressure of the air-vapor mixture within the tank. The "breathing" of the tank is caused by the inflow of air from the atmosphere during certain periods of the day and the expulsion of the air-vapor mixtures at other times, caused by atmospheric variations. The pressure built up within a tank and the amount of gasoline in the air-vapor mixture are both a direct function of the temperature existing within the tank. Therefore, two of the most common methods for reducing evaporation losses from bulk-station tanks are: (1) The use of vapor-tight tanks equipped with relief valves and operated at 1 or 2 ounces of pressure and about .5-ounce vacuum; (2) reducing the temperature of tanks and their contents by painting them a light color, by insulation, and in some instances by using water sprays. Water sprays, although effective, usually are too expensive to operate economically. In order to determine and compare the effects of various colors, insulation, and pressure in reducing the evaporation losses of gasoline held in storage in bulk-storage tanks, the Bureau of Mines made observations from May 29 to October 15, 1930, on five horizontal tanks of 12,000-gallon capacity each, which were erected at the plant of Black, Sivalls and Bryson Manufacturing Co., Kansas City, Mo. This report gives in detail the results of these evaporation tests.

Jan 1, 1931

By R. J. Leary

The natural gas-air burner described in this report was designed and constructed to meet the thermal requirements of a convective process for heating steel scrap. This process involved downward combustion of natural gas with air, blending the combustion products with diluent air, and then passing this tempered stream of gases downward through a porous bed of steel scrap contained in the furnace chamber. The scrap would be heated to a temperature limited by the adiabatic flame temperature of the gas stream in a period that depended on the rate at which heat was supplied per unit of bed cross section. The temperature of the gas stream would be limited to that beyond which an objectionable degree of oxidation would occur; for carbon steel this limit had been found to vary from 1,900° to 2,100° F. with the superficial velocity of the gas stream. The productivity of the process was dependent on the rate of heat input per unit of furnace cross section; for the 3-foot-diameter experimental furnace an input of 680,000 B.t.u. per hour was desired. The burner described was designed to meet these conditions of temperature and heat input. It provided for three streams of entering gases: (1) A primary air-fuel mixture too rich to be combustible, that is, above the upper flammable limit; (2) secondary air for combustion of the primary mixture; and (3) tertiary air, principally for cooling the combustion products to the temperatures desired for process operation. Downward combustion of the primary and secondary streams occurred in a flame stabilized on an annular port, while tertiary air flowed in an annular path surrounding the port and also through an axial channel whose wall formed the inner ring of the annular port. This burner performed beyond the designed heat-input rates while producing stable flames, which were adjusted readily to the temperatures desired. Gas-stream temperatures were easily controlled to within 15° F. of the desired value by simple manual adjustment of the flow valves.

Jan 1, 1959

By Christopher Van Dyke, Knox Van Dyke, Lixin Wu, Jaime Gutierrez

"I. INTRODUCTION(SILICA, THE LUNG, INFLAMMATION, AND FIBROSIS)Inhalation of respirable-size silica (0. I to 5 µm in diameter) deposits the particles in the deep spaces of the Jung where oxygen is exchanged. The resulting pattern of inflammation is substantially different compared to that observed from other inhaled substances such as carbon, polystyrene titanium dioxide etc. 1 Following the inflammatory reaction the body attempts to isolate the damage by walling off the area via fibrosis. 2 The unique nature of the inflammatory response to silica makes it logical to infer that fibrosis is a later-stage manifestation of the initial inflammatory damage. In addition to the inflammation extensive lysis and cellular death particularly to macrophages and neutrophils, can occur, depending on the dose of silica.' The ingestion of significant amounts of silica by macrophages and neutrophils produces an inflammatory sequence which activates the lipoxygenase pathway of arachidonic acid metabolism and produces platelet activating factor (PAF) and leukotrienes (LT).4·5II. CALCIUM IONOPHORE MIMICS SILICA TOXICITY IN VITROPhagocytic cells exposed to silica in vitro produce PAF and LT. This response is reminiscent of phagocytic cells exposed to the calcium ionophore (A23 l 87) in the presence of ionic calcium.6-8 A23 l 87 forms a complex with free ionic calcium which passes through cellular membranes, thus transporting calcium inside the cell. The increased intracellular calcium concentration triggers the production of small amounts of prostaglandins large amounts of LT. PAF and. depending on dose cellular death (see Figure 1 ). Could silica cause LT production and cellular death by a similar mechanism? How could silica - an inert solid - act in a similar fashion as a soluble stimulant? Clearly the negative SiO2 and OH- surface of silica can bind calcium ions9 and therefore could theoretically act as a solid-state ionophore releasing bound calcium inside of cells following phagocytosis."

Jan 1, 1998

By Peter N. Gabby

In 1992, the Bureau of Mines conducted a mineral resource investigation of the 27,034-hectare Steel Mountain/Yuba River study area and the 16,544-hectare Breadwinner study area. There were approximately 535 lode and placer claims in or partially in the Steel Mountain/Yuba River study area, and 84 lode and placer claims in or partially in the Breadwinner study area. In the Atlanta and Rocky Bar mining districts, both adjacent to and in the Steel Mountain/Yuba River study area, 30,232.4 kg (972,000 02) of gold and 62,838.3 kg (2,020,000 02) of silver had been produced. Most of this production came from outside the study area. Placer properties adjacent to (and a few in) the Breadwinner study area had production of 93.1 kg (2,992 oz) of gold and 20.0 kg (642 02) of silver. Twelve properties in the Steel Mountain/Yuba River study area have potential for resources; eleven have alteration and/or mineralization similar to that found at Atlanta with potential for gold, silver, and tungsten resources, and one has alteration and mineralization associated with polymetallic vein type deposits with potential for gold, silver, copper, lead, zinc, and tungsten resources. Adjacent to the study area, large bars of gold-bearing gravel can be found along the Middle Fork Boise River. Four properties in the Breadwinner study area have potential for mineral resources; one has alteration and mineralization associated with skarn, polymetallic vein, and, possibly, copper-molybdenum and molybdenum porphyry types of deposits; two have alteration and metal assays associated with polymetallic vein, and possibly copper-molybdenum and molybdenum porphyry types of deposits; and one has alteration and mineralization similar to that found at Atlanta. These four have potential for gold, silver, copper, lead, zinc, molybdenum, and tungsten resources Adjacent to and extending into the Breadwinner study area are large bars of gold-bearing gravel along North and Middle Forks Boise River.

Jan 1, 1993

By A. J. Kraemer, H. M. Thorne

The following account of oil-shale operations in Australia is based upon infor- mation obtained by the authors while visiting Australia from September 15 to October 7, 1947, supplemented by published data, and augmented by analyses of samples of oil shale and its products at the Oil-shale Research and Development Laboratories of the Bureau of Mines at Laramie, Wyo. The primary objective of the authors' trip to Australia was to obtain, first hand, information regarding the equipment and methods used by National Oil Proprie- tary, Ltd., at Glen Davis, New South Wales, in mining oil shale, extracting oil from it, and refining the shale oil. This company was operating the only oil-shale plant that had been active in Australia since 1945. The plant comprised an oil-shale mine, 104 modified Pumpherston (Fell) retorts in 2 batteries, a hele refinery, and a 3-inch gusoline pipeline to the railroad loniing terminal t Sun Junction, 30 miles away. There were, also, the usual and necessary any uralities, such as a power house, mechanical shops, offices, and laboratories One Information regarding the company's operations was wance because of its bear- Ing upon the synthetic liquid fuels program of the Bureau of Mines, pursuant to the Synthetic Liquid Fuels Act of April 5, 1944 (30 U.S.C., 321-325, as amended). objective of the Bureau's program. In accordance with the maniate of the Act, is to furnish American industry cost and engineering data necessary for the development of synthetic-liquid fuel industry, and an obvious means of obtaining some of these data is to learn how oil shale is being mined and retorted and how shale oil is re- rined in countries where these operations have been conducted on a plant scale for many years. The authors spent 2 weeks at the plant of National Oil Proprietary, Lt., at Glen Davis, and were afforded every opportunity to obtain letailed and specific information regarding all aspects of the company'a operations.

Jul 1, 1951

By J. S. Kennedy, M. M. Fine

"INTRODUCTION Barite is one of the major industrial minerals whose production has increased considerably in the last 10 years. In 1935 domestic production of barite was 218,075 tons and. had increased by 1944 to 515,136 tons. 3/ Most of the primary uses for barite and barite products were developed before 1935, so the increase in barite production reflects the growth of industry in general rather than any recent developments in barite technology.The principal uses for ground and crushed barrite are as a weighting agent in heavy drilling fluids, as a filler in rubber and other materials, as a pigment and extender in paints, and as a flux in glass melt. In addition, a considerable' quantity of barite serves as the raw material for the manufacture of lithopone and barium chemicals.Specifications for barrite vary widely and depend primarily on the use to which the material is put. The primary requisites for barite used in heavy drilling muds -are that it have a minimum specific gravity of 4.2 and be very,low in soluble salts. A minimun barium sulfate content of 92 percent may be specified; but this is less important than the gravity. 4/ In addition before consumption the material must be ground to '92 percent minus 325-mesh. 5/ Lithopone and chemical manufacturers require a minimum of 94 Percent barium sulfate, a maximum of 1.0 percent iron oxide, and not more than a trace of fluorine. 6/ Barite used as fillers in light-colored products should be of fairly high grade, but the filler used in dark products may be considerably lower grade.Glass barite should contain a minimum of 96 percent barium sulfate, not more than 3 percent moisture, a maxium of 0.2 to 0.4 percent iron oxide, and not more than a trace of titanium oxide. Particle size is a matter of some importance in glass barite, also. 7/"

May 1, 1948

By A. J. Farstad

The use of radio signals for underground communications was considered as early as the mid-1920's [1] - [4] . However, early experiments did not produce promising results with the type of equipment that was available then [5] . With advancements in solid state technology many of the schemes considered impractical in the early days suddenly became practical. The properties of electromagnetic wave behavior in conducting media have been intensively studied by Wait [ 6] and others and can be utilized not only in communication with trapped miners, but also as a means of locating their position. This report deals with the development of portable electromagnetic equipment, powered by the miner's conventional lamp battery, which can be used to alert surface rescue personnel of the trapped miner Is location. The Westinghouse Georesearch Laboratory (WGL) under BUMINES sponsors hip initially approached the trapped miner location problem using seismic techniques. It was learned from this effort that two serious shortcomings of seismic techniques are (1) the extremely weak signals available on the surface from miner generated hammer blows, requiring long processing times at the surface receiver, and (2) the relatively slow procedure of deploying geophone arrays to sense the seismic uplink signals. By contrast, the electromagnetic techniques have proven much more practical from a deployment time standpoint and in most cases have also proven to be more accurate in determining location. Furthermore, these techniques have been successfully tested using a receiver in a heli- copter for reconnaissance purposes. However, before any electromagnetic location technique can become fully operational, the miners themselves must be equipped with emergency transmitters to be carried with them on each work shift. Consequently, much emphasis has been placed on the development of extremely lightweight transmitting equipment. The performance of some of the electromagnetic location equipment developed by Westinghouse will be described in the following sections. 2.0 Basic Concepts Theoretical concepts for locating magnetic dipoles in the earth have been treated by Wait [ 7] and Olsen [ 8] . A generalized curve for the attenuation of magnetic fields in a conducting half-space is derived from

Jan 1, 1973

By B. R. Mohal, F. F. Aplan, S. Chander

"Dust abatement by water sprays involves the subprocesses of 1) collision between dust particles and water droplets, 2) adhesion of particles to droplets, and 3) engulfment of particles by the droplets. A review of the fundamental aspects of these subprocesses shows that collisions between particles and droplets are determined by aerodynamics and the size and surface charge of the particles and of the droplets. However, the adhesion and engulfment subprocesses depend upon the wetting characteristics of the particles. Although wetting agents (also known as surfactants) have been used as dust suppressants in several investigations, conflicting results are available regarding their effectiveness. In this paper, we show that these results can be explained if the effects of coal rank on surfactant adsorption and wetting characteristics are taken into account.The influence of several nonionic surfactants containing polyethoxy adducts on the wetting behavior of coal is presented. The wetting was determined by a modified Walker Test method, and contact angle measurements. The results show that the wettability of coal depends upon coal rank, structure of the hydrocarbon chain of the surfactant, and the number of ethoxy groups in the molecule.IntroductionDue to the inherent nature of the mining process, a large number of particles are generated, a portion of which becomes airborne to create dust. Dust can be aesthetically and environmentally unacceptable and it can also be explosive. Fine particles in the respirable size range ( < 5 urn) are con-sidered to cause lung diseases, namely, silicosis, pneumoconiosis, etc.(1) Several approaches to reduce dust in mine environments are practiced throughout the mining industry. These include decrease in generation of dust through improvements in mine machinery, ventilation (in which lower dust levels are achieved by dilution of contaminated air with clean air), and dust removal methods. Water sprays are most commonly used to remove dust par-ticles. Recently, scrubbers are reported to have been installed on mining machines to remove dust,(2,3) which also make use of water sprays to reduce dust."

Mar 1, 1989

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"DIGREGORIO, K. A., E. V. CILENTO, AND R. C. LANTZ. A kinetic model of superoxide production from single pulmonary alueolar macrophages. Am. J. Physiol. 256 (Cell Physiol. 25): C405-C412, 1989.-A kinetic model was developed to describe the production of superoxide (02) by single pulmonary alveolar macrophages (PAM). Model predictions were compared with experimental results obtained from single rat PAM. The 02 was quantified by measuring the reduction of nitro blue tetrazolium (NBT) to a diformazan precipitate (NBTH,) from video-recorded images of individual cells. The kinetic model considered three reactions: 1 ) the production of extracellular 02 from the reduction of oxygen by NADPH oxidase using intracellular NADPH as the substrate, 2) the subsequent dismutation of 02 to form H,O,, and 3) the reaction of 02 and NBT to form diformazan. NBT specificity for 02 was analyzed by comparing results in the presence and absence of superoxide dismutase (SOD) that catalyzes the dismutation of 02 to H,O,. Measured PAM heterogeneity was accounted for by varying the concentration of intracellular NADPH, its rate of depletion, and the concentration of intracellular NADPH oxidase in the kinetic model. Model predictions compared favorably with experimental results except when SOD was present. This discrepancy may be due to diffusional limitations because NBT is a relatively small molecule (818 mo! wt) compared with SOD (34,000 mol wt). In addition, the cell surface is both ruffled and negatively charged, which may introduce steric hindrances and/ or electrostatic effects, since SOD is also negatively charged, whereas NBT is positively charged.PULMONARY ALVEOLAR MACROPHAGES (PAM) protect the lungs by phagocytizing foreign debris and bacteria. This process is accompanied by the production of superoxide anion (02) at the surface of the plasma membrane (3, 31). Superoxide readily dismutates to form H20 2 and subsequently, other oxygen metabolites which have been shown to be both antibacterial and cytotoxic (21, 25, 35).Superoxide is produced from the reduction of extracellular O, at the surface of the cell membrane by NADPH oxidase by the following reaction (3, 4)"

Jan 1, 1989

By J. E. Tiffany

"The new permissible blasting device, Cardox, utilizes as a blasting agent liquid carbon dioxide which is discharged.as a gas from a steel container or shell. The loaded shell is placed in a borehole, stemmed, and tamped in a manner similar to that employed with explosives, and is fired by electricity.The Bureau of Mines' approval for use of the device in coal mines was granted as Approval No. 1 under date of October 3, 1928; as the result of tests made under the conditions and requirements of Schedule 20. There have been three subsequent extensions whereby minor modifications in the original design were granted.The permissibility of the device is subject to the following conditions; (1) It shall be in all respects similar to the sample submitted for tests; (2) certain thicknesses of disc and. weights of heater ingredient and of carbon dioxide, all of which are set forth in Table 2 under the provisions governing permissibility, must be used: (3) the rear cap must always be in place after the shell has been charged, to prevent accidental firing; and (4) firing must be done by means of a permissible-type blasting unit.The permissibility of Cardox was established by gallery tests similar to those used in testing explosives for permissibility. In these tests the shell was discharged into gallery 1 without causing any ignition of gas and air or of gas, dust, and air mixtures there. The conditions of charging the shell, such as weight of the ingredients of the heater element, the carbon dioxide charge, and thicknesses of the disc, were varied according to the conditions under which it would be likely to be used in blasting. The tests made in gallery 1 are here described in detail, as are also the tests which have been made for determining the propulsive strength of the device and the quantities of poisonous gases given off when a shell is discharged."

Mar 1, 1929

By Charles L. Kimbell

Bulk carriers, freighters, and tankers are the three classes of seagoing vessels engaged in transporting mineral commodities. However, vessels in these classes are not wholly devoted to mineral commodity transport, as seen in tables 16 through 22. Bulk carriers move considerable tonnages of agricultural products as well as crude minerals, their concentrates, mineral fertilizers, and the like. Freighters, owing to their great variety, can be devoted wholly to hauling mineral products or wholly to non mineral goods, as well as carrying mixed mineral commodities and non mineral commodities. They include general cargo ships, full container ships, partial container ships, roll-on/roll-off ships, and barge carriers. Tankers, although largely engaged in moving crude oil and refinery products, also transport liquid chemicals, molasses, wine, liquefied natural gas, and other fluids. Table 16 shows the distribution of the world&apos;s merchant fleet by vessel type in terms of the number of vessels, their gross tonnage, and their deadweight tonnage. The increase of nearly 1.5 % in the number of vessels between 1990 and 1991 compared with a 2.7% growth in gross tonnage and a nearly 2.3 % increase in deadweight tonnage points to an increase in the average size of vessels. Of the four categories of vessels reported, all showed increases in number and in deadweight tonnage between 1990 and 1991 except for "other," and on the gross tonnage basis, all groups registered increases. Although physical characteristics of vessels such as size, draft, crew requirements, type of propulsion system, ratio of gross tonnage to cargo tonnage, and fuel costs have undeniable influences on shipping industry performance, problems of and changes in the quantity and types of materials moved also significantly affect the shipping sector of the world economy, and thus have a bearing on the minerals sector of that aggregate. Unfortunately, comprehensive global data reflecting changes in these critical variables are not published.

Jan 1, 1993

By T. L. Joseph

The size and accessibility of the Minnesota manganiferous iron ore deposits make them attractive as a potential source of erromanganese, which is essential in the production of steel. For several years the Bureau of Mines has been conducting experiments to determine the feasibility of producing ferromanganese from these ores by a three-step process which involves (1) the smelting of the ores in the blast furnaoe to produce a high-phosphorus spiegel; (2) the treatment of the spiegel produced from step 1 in an electric or open-hearth furnace to separate the manganese from the phosphorus and the iron; and 3) the smelting of the high-manganese slag from step 2 to produce forromanganese. The details of the first two steps of the process and the results of tests with the experimental furnaces Lave been given in previous reports.5 The m$ or part of the experimental work on the second step has been conducted in a half-ton open-hearth furnace. Some preliminary tests showed, however, that the electric furnace has some distinct advantages over the open hearth for producing, from high-phosphorus spiegel, a slag containing from 45 to 55 per cent manganese and phosphorus and iron in amounts required for ferro-grade ore. The electric furnace tests described in this paper were made to get more information as to the possibilities of the electric furnace in connection with this problem and to study the fluxing effect of alumina on high-manganese slags. Herty, Conley, and Royer have reported&apos; results of laboratory tests which showed that slags containing from 60 to 75 per cent MnO, from 8 to 10 per cent S102, and small amounts of CaO MgO, and FeO, were sufficiently fluid at 1,450° to 1,550° C. to pour readily if 12 to 14 per cent alumina was present. With a normal A1203 content resulting from the A1203 in the

Jan 1, 1931