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By B. H. Eccleston

Experimental data were obtained from two medium-duty diesel engines derated to qualify for use in underground mines. Gaseous and particulate emissions from these engines were measured and results provide information on the effect of exhaust treatment devices on the emissions. The devices in the study were a catalyst, a particulate trap, and an exhaust gas cooler of the water scrubber type. Emission levels of carbon monoxide and hydrocarbons were observed to be very low in comparison with emission levels of comparable engines in full-rated operation. Oxides of nitrogen and benzo(a)pyrene content of the exhaust also were found to be somewhat low in comparison with previous findings. For particulate reduction, the combination of a particulate trap and a scrubber was observed to be the most effective combination tried; in some cases, over 60 pct particulate reduction was effected by the trap-scrubber combination.

Jan 1, 1981

By l.J Prosser

from 1990 to 1996, 16 states reported 92 injuries from falls of roof, rib or face in the more than 90 underground stone mines in the United States (Fig. 1). Missouri, Pennsylvania and Kentucky accounted for 48% of the total number of injuries (Fig.2). Of this total, 11 miners were killed. Of the 11 fatalities, 10, or 91 %, were associated with unrecognized loose or failed rock within the roof beam. Additionally, unrecognized roof beam failures resulted in a majority of the falls of ground injuries occurring in underground US stone mines from 1990 to 1996.

By John E. Conley

The great demand for metallic aluminum for the prosecution of World War II caused the consumption of bauxite, the common ore of aluminum, to increase greatly. Prior to the war, the domestic deposits 'of bauxite, which occur chiefly in Arkansas and less extensively in Georgia, Alabama, and Mississippi, supplied only: about 30 ,percent of the ore required for aluminum-metal production and approximately 40 percent of alumina for all purposes. Enemy activities during the war seriously interfered with shipment of bauxite from the normal peacetime source in Surinam, Netherlands Guiana, South America, and focused attention on the necessity for increasing production from known domestic deposits. Even in peacetime, the production of aluminum ore in the United States could not satisfy requirements. Field drilling and exploration by Bureau of Mines engineers resulted in the discovery of important tonnages of high-grade bauxite suitable for treatment by the conventional Bayer process, Although an ore containing approximately 55 percent Al2O3 and only 2 to 4 percent SiO2 is preferable, it was necessary to use ores containing up to 8 or 10 percent SiO2. Because of the lower recoveries of aluminum with increased silica content, the Reconstruction Finance Corporation, through the Metals Reserve Company, established a base price of $4 for a 50-percent Al2O3 ore, containing 13-percent silica, with a premium or penalty of 14 cents for each percent of Al2O3 over or under 50; each percent of SiO2 under 13 was awarded a 20-cent premium, and each percent over 13 suffered a penalty of 43 cents; all prices were on the basis of 1 long ton of ore, dry basis.

Jan 1, 1949

By Hylton R. Brown

This publication, an abstract of a progress report covering an investigation of hazards in thermal coal-drying plants has been prepared according to the suggestions and recommendations of a committee6/ appointed by J. J. Forbes, Director of the Bureau of Mines, when the original report was reviewed at a meeting of representatives of the mining industry, operators of coal-drying plants, coal-mine workers, and the Bureau in Washington on May 6, 1955. The investigation on which the report is based was made in accordance with action taken at a previous conference in Washington on May 19, 1954, called by Director Forbes to consider what should be done to prevent explosions and fires in coal-drying plants. Scope of Investigation The investigation was planned to obtain information considered essential for properly appraising fire and explosion hazards in different types of coal driers. A questionnaire sent to Bureau personnel provided preliminary information on coal-drying facilities at more than 270 preparation plants. Information on methods used in operating different types of driers, with their furnaces, fans, cyclones, and other auxiliary equipment, was obtained by personal visits or conferences with the operators at 13 plants. Factual data on operating temperatures, composition of the drying gases, air flow, dust loading of the air or gas currents, use of water sprays, auxiliary air controls, and other factors were obtained by conducting full-scale tests at six different plants and making laboratory investigations with samples of dust and gas collected during the tests.

Jan 1, 1956

By J. A. Organiscak

The Bureau of Mines recently investigated dust generation and methane liberation during half-and full-web cutting at a double-drum shearer longwall face. This study was conducted to ascertain the health and safety aspects of wider web shearing at longwalls. Results from these underground tests showed that deeper web cutting reduced dust generation and methane liberation per ton of coal mined, while significantly improving shearer production rates. When cutting with the airflow (head-to-tail cut pass) full-web cutting decreased dust generation per ton by 16 pct at the shearer and 6 pct at the tailgate, with an increase in shearer production rate of 72 pct. Methane liberation per short ton also deere~sed by 36 pet at the shearer and 22 pct at the tailgate. Full-web cutting against the airflow (tail-to-head cut pass) decreased dust generation per ton by 41 pct at the shearer and 37 pct at the tail-gate over half-web cutting, with an increase in shearer production rate of 61 pct. Methane liberation per ton also decreased by 35 pct at the shearer and 41 pct at the tailgate. These improvements for full-web cutting are a reflection of improved cutting efficiency (less dust and methane produced from cutting) and less new face area exposed per ton of coal mined (less methane liberated from face per short ton of coal mined).

Jan 1, 1988

By Jr. Norman

The Bureau of Mines investigated the thermoelectric properties of yttrium selenides and tellurides from room temperature to 900° C. X-ray crystallographic data were determined for the yttrium-selenium and yttrium-tellurium compounds that were orthorhombic with a cubic substructure. The yttrium selenides and tellurides exhibited semimetallic to insulator conduction properties with figures of merit of 10-9 to 10-4 °C-1. The mono-selenide and monotelluride behavior was partially degenerate; unsatisfied bonds were the source of the large number of charge carriers. The higher stoichiometry selenide compounds were intrinsic semiconductors) but with high electrical resistivities. A critical defect or impurity ionization energy for carrier activation appeared to exist in the majority of telluride compounds. Mobility and energy band determinations are required to interpret completely the observed effects in most of the compounds studied.

Jan 1, 1966

By W. L. Falke

Research was conducted to develop methods on a laboratory scale for recovering manganese from manganiferous slimes and limestones . The procedure is a low- temperature modification of the carbamate process , in which manganese is dissolved and the valence reduced by treating slimes and limestones with controlled amounts of sulfurous acid . Manganese ( II) hydroxide is precipitated and leached with ammonium carbamate solution , and manganese carbonate is separated by warming the leach solution . A major portion of the reagents is regenerated and recirculated . About 75 percent of the total manganese in manganiferous slimes , and from 50 to 75 percent of the total manganese in manganiferous limestones , are recovered as manganese carbonate containing 45 percent manganese .

Jan 1, 1964

By J. G. Schoning

The Holmes Safety Association is an offspring of the Joseph A. Holmes Safety Association which was organized in Washington, D. C., in 1916 at a meeting of representatives of twenty-four leading mining associations connected with every branch of the United States mineral industries. The purpose of the meeting was to do honor to the memory of Joseph A. Holmes, one of the founders of the United States Bureau of Mines and its first director, whose death had occurred the year before on July 12, 1915. In deference to what was believed would have been the expressed wish of this great humanitarian and benefactor of the mineral industries, it was decided to establish a national safety organization to cover the mineral indus¬tries exclusively; out of respect for his memory and service, the organization was named the Joseph A. Holmes Safety Association. On receiving requests from several mining districts, in 1922 a number of chapters ware established in several mining States.

Jan 1, 1929

By Earl L. Hastings

Although the principal market for diatomite in the United States is in the East,4 production of the material is presently restricted to the West, because the deposits are larger, mining costs are cheaper, and the quality of product is better than that obtained from other domestic deposits. However, Tallahatta diatomite, occurring in Choctaw and Clarke Counties, Ala., has a freight rate advantage, which should encourage competition for those market that are now being supplied with the purer diatomites from the western deposits. For this reason, diatomite occurrences in the Tallahatta formation were examined by the Bureau of Mines and physical properties of samples from the deposit were determined to obtain additional data for use by any potential producer who wished to evaluate the material for its commercial possibilities. In 1894 K. M. Cunningham5 found that the buhrstone formation (now known as the Tallahatta formation) contained "siliceous shells of marine diatoms, radiolaria and foraminifera, thus being rather of the nature of tripoli or diatomaceous earth than of a true clay." Cooke6 and Semmes7 also reported the Tallahatta formation to be composed principally of diatomaceous earth with accompanying beds of sand, clay, and sandstone.

Jan 1, 1963

By David C. Byrne

PURPOSE: Evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. RESEARCH SUMMARY: The results of previous NIOSH research show that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and gender. Using hearing thresholds at 4,000 Hz as an indicator, coal miners experience hearing loss 2.5 to 3 times greater than would be expected for persons not exposed to occupational noise. At age 50, 90% of coal miners and 49% of metal/nonmetal miners were found to have a hearing impairment. In comparison, only 9% of a nonoccupationally exposed control group had a hearing impairment at age 50. There are numerous barriers to the prevention of hearing loss among miners. In an effort to overcome some of these obstacles, this work was initiated to evaluate practical technological advances in level-dependent hearing protectors and inexpensive personal acoustic monitors. Experiments will involve analysis of this new technology under both laboratory and field conditions. Laboratory components will consist of controlled studies using an anthropometrically correct test fixture as well as human subjects to evaluate the adequacy/effectiveness of various hearing protective devices. Electroacoustical performance testing of new noise monitors will also be conducted in a laboratory setting. Subsequent field studies will determine the actual usefulness and practicality of the personal protective/monitoring equipment as used in different mining situations. It is anticipated that increased on-the-spot awareness of hazardous noise levels and the availability of better-suited hearing protectors will provide a degree of protection beyond what is currently attained in different mining environments. Therefore, the intent of this project is to identify and adapt new acoustical technologies and products that have a direct application to individual mine workers. With increased knowledge of these technological advances, a greater demand for similar devices will likely occur, which, in turn, will lead to a better understanding and awareness of hearing loss prevention methods throughout the mining community. The ultimate goal is for widespread integration of useful hearing loss prevention products and devices into the daily routines of miners

Jan 2, 2000

By E. D. Eastman

There are three researches upon the specific heat of water vapor by the method of explosion that are sufficiently advanced in technique and suitable in plan to justify careful study of their results , with the double purpose of fixing the best available experimental values and indicating the attainable accuracy of the method. These three researches comprise the work of Pier , Bjerrum , and Siegel.5 The work of earlier date than Pier's suffers from obvious inaccuracy of measurement , while the experiments more recent than Siegel's , such as those of Womersley6 , of Bone and his collaborators , and of Maxwell and Wheeler , 8 are for the most part not well designed for the accurate determination of the heat capacities in question . Some of the errors to which they are especially subject have been discussed by David and by David and Thorp.

Sep 1, 1930

By A. B. Needham

Graphite is a raw .material of considerable importance in both waxy and peace. Two types of graphite, classified according to particle size as flake and fines, are used, but the former is in much greater demand. The principal wartime use of graphite is in the manufacture of crucibles for melting brass and special alloys of copper and steel. Other uses in both peace and war are as lubricants, for foundry facings, and in paints, electrodes, batteries, motor and generator brushes, and a variety of other commodities. . This paper describes the operations of the Southwestern Graphite Co. of Los Angeles, Calif., which produces both flake and fine graphite from a property in Burnet County, Tex.

Jan 1, 1946

By J. P. Bennett

The Bureau of Mines investigated the dimensional changes of ceramic materials exposed to acid environments to evaluate construction materials for emerging technology in chemical and metallurgical processes. Six commercial ceramic materials (two red shale, two fireclay, one silica, and one silicon carbide (SiC» were exposed to H20, 20 and 30 wt pct HCl, 40 and 60 wt pct HN03, and 10 and 50 wt pct H2S04 at temperatures from 50° to 90° C for 300 days. Linear expansions ranged from a low of -0.02 pct for the silica to a high of 0.45 pct for the red shale. A general ranking of the volume expansion of the materials tested, (from high to low), is as follows: high-porosity red shale A and fireclay B » low-porosity red shale B and fireclay A > silicon carbide and silica. A general ranking (largest to smallest) of the effect of exposure environments is HCl > H2S04, HN03 > H20. An autoclave test method was evaluated. Data obtained from 8-to 24-h exposures were compared with data obtained from the 300-day exposures. The relative expansion trends were similar, indicating that this method could be used as an accelerated test.

Jan 1, 1988

By Fred D. DeVaney

The Mesabi iron district of Minnesota has a potential production of over 50 million tons of iron are annually. The large shipments of ore each year are gradually depleting the reserves, and if the present rate of production is to be maintained there must be a growth in the present available ore supply. Growth is a natural course. The growth of a city may be affected by the addition of city blocks or by the improvement of utilities necessary for its betterment. These may go on in the order named or concurrently. The city-block type of growth of the Mesabi has been tremendous, and the "betterment" type has followed in due course. Probably the former has reached its limit, and if so, more time will be allotted to the latter. It is not the in¬tent of this paper to present either a eulogy of the wonderful mining methods or a history of the milling, but it is pertinent to say that if the lean-ore area continues to produce, the continuance will be more the result of further improvement of milling methods non well under way than of extension of boundaries by the city block plan of growth.

Jan 1, 1932

By L. L. Brown

As part of the Federal effort to help maintain an adequate supply of fertilizer materials, the Bureau of Mines conducted research to characterize complex low-grade Michigan phosphate materials and to devise methods for recovering fertilizer-grade phosphate concentrates. The rock is from middle Precambrian sedimentary formations in the Marquette Range located in the central part of the Upper Peninsula of Michigan. Occurrence of phosphate-bearing sediments in Precambrian rocks is rare. This deposit, containing 12 to 15 pct P205, is believed to be the richest Precambrian phosphate deposit in the United States. Petrographic examination showed that the conglomeritic rock contains crystalline apatite both in "black pebbles" and in quartz matrix. Attrition scrubbing and sizing tests showed that there is no tendency for phosphate to concentrate in any of the sized fractions. In beneficiation tests, which included grinding to minus 325 mesh followed by phosphate mineral flotation using a fatty acid-fuel oil collector, a phosphate concentrate was obtained that had a grade of 30 pct P205 and a P205 recovery of 72 pct. This concentrate should be suitable for fertilizer manufacture.

Jan 1, 1981

By Barry W. Klein

The U.S. economy was considerably stronger in 1976 than in 1974 or 1975. Real gross national product (GNP) rose sharply in the first quarter of 1976 and then increased at a more moderate rate for the remainder of the year. The unemployment rate fell until June and then increased for moat of the remainder of the year, finishing at the same rate as it had started the year. The inflation rate continued to decline in 1976. Reasons for the relatively low rate (compared with those of 1974 and 1975) included small increases in food prices and only moderate increases in energy prices. Total U.S. output measured in terms of GNP increased 11.6% in 1976. Real GNP in 1972 constant dollars rose 6.2%. Inflation as measured by the implicit price deflator increased 5.1%. In real terms, gross private domestic investment for residential structures rose 22.7% in 1976 after declining 14.7%a in 1975; State and local Government expenditures increased 1.4% in 1976; and personal consumption expenditures for services rose 4.5%. The Federal Reserve Board (FRB) index of industrial production increased 10.2%.

Jan 1, 1978

By M. Hertzberg

This Bureau of Mines report proposes a new methodology for estimating industrial dust explosion hazards in terms of three probabilities or co-factors: The dispersion of the dust, the existence of a flammable dust concentration, and the presence of an effective source of ignition. This method or rationale is proposed as a replacement for the "explosibility index" that was first suggested 25 yr ago, but which, by consen-sus among leading researchers in the field, is now outdated. This report presents a detailed critique of the deficiencies of that old, material-oriented index, and develops the logical rationale for its re-placement by an approach that is better suited for quantitative hazard evaluations. A variety of such evaluations are illustrated, which show how a quantitative prediction of explosion frequencies can be obtained from laboratory measurements and operating conditions in a given indus-trial facility. The method has some pitfalls, particularly as they re-late to the correlation of events or their randomness. These are discussed, as well as the method's other limitations and uncertainties. This work is intended to provide a beginning to a quantitative approach to explosion hazard assessment. To that end, a new method is proposed for estimating thermal ignition probabilities in terms of the measured laboratory autoignition temperature of a dust, its relationship to the operating temperature, and its distribution within a given industrial system.

Jan 1, 1987

By William M. McKewan

The U.S. Bureau of Mines has established a wire rope research laboratory to examine the factors that affect the life of wire rope. Ropes of sizes ranging from 3/4 to 2 in. in diameter and from 2 to 35 ft in length were tested to determine their breaking strength, elongation, and torque. This was done to characterize the test equipment on ropes used in mine hoisting systems.

Jan 1, 1990

By J. H. Rose

This paper describing the milling practice at the Magma Copper Co., Superior, Ariz., is one of a series being prepared by the Bureau of Mines on milling methods and costs in the various mining districts throughout the United States. ACKNOWLEDGMENT The authors wish to acknowledge their indebtedness to William Koerner, general manager of the Magma Copper Co., for permission to prepare this article; to J. S. Garrott, former mill superintendent, for the historical facts; and to Walter Cooksley, general foreman, for his assistance in obtaining the data.

Jan 1, 1930

By R. H. Reist, R. D. Dey, V. Castranova, J. P. Durham, Y. Rojanasakul

"Silicosis is a fibrotic pulmonary disease produced by inhalation of silica-containing dusts (Peters, 1986). Chronic silicosis may develop 20-40 years after initial exposure to crystalline silica, and the disease may progress from a simple to a complicated form. Few symptoms are evident in simple silicosis with pulmonary function being relatively normal. However, chest radiographs reveal small rounded ·opacities in the upper lobes of the lungs. These silicotic nodules consist of collagen arranged in a distinctive circular pattern. As fibrotic changes become more severe, the disease progresses to complicated silicosis (progressive massive fibrosis). Complicated silicosis is associated with shortness of breath and decreases in pulmonary function characteristic ofrestrictive lung disease. Chest x rays reveal numerous large silicotic nodules which may be associated with scar emphysema. Several mechanisms have been proposed to explain the cellular events which result in silica-induced lung damage and fibrosis (Lapp and Castranova, 1993). They include: ( l) direct cytotoxicity of silica, (2) activation of oxidant and enzyme release from alveolar macrophages, (3) recruitment and activation of polymorphonuclear leukocytes, and (4) stimulation of fibroblast proliferation and collagen synthesis.Tetrandrine is a bisbenzylisoquinoline alkaloid derived from the Chinese herb Radix Stephania tetrandra. It has a molecular weight of 622.73 and an empirical formula of C38H420 6N2. The chemical structure of tetrandrine has been published previously by our laboratory (Castranova et al., 1991 a). Its structure is characterized by methoxy groups at C7 and C12 , uncharged nitrogens at N2 and N’2 and two 17-carbon ring members connected by a double oxygen bridge between Ca-C7 and C11-C12. Tetrandrine has been shown to reduce both silica-induced fibrosis and the elevation of lung collagen content in rats (Huang et al .. 1981; Yu et al., 1983; ldel, 1987). Furthermore, tetrandrine has been used as an antifibrotic agent in Chinese clinical trials (Li et al.. 1981 ). Preliminary results suggest that administration of tetrandrine to patients with silicosis results in substantial improvement of symptoms, increases in diffusion capacity, and decreases in the size of shadows on lung x rays."

Nov 1, 1995