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By A. W. Fahrenwald

"About two years ago the Bureau of Mines, Department of the Interior, and the University of Idaho undertook an investigation of classification in its relation to table concentration of Idaho ores. The cooperation of the management of the Bunker Hill & Sullivan Co. in placing at our disposal their West Mill and facilities as desired, offered an unusual opportunity for studying the field of hindered classification in its practical and economic relation to table concentration.It has been shorn theoretically, and demonstrated experimentally, that ore products are more easily and economically concentrated on tables if the natural feed, consisting of various minerals and of all sizes of particles of each mineral, be classified or grouped into a series of products in which the mineral particles of greatest density are small in diameter relative to the diameter of the mineral particles of lesser density. Products in which the maximum difference in diameter of light and heavy minerals occurs are to be obtained only by true hindered settling classification. To our knowledge there has never been a really good hindered settling classifier used in practice and the present tendency seems to be to by-pass any attempt at such classification.After a careful study of the nature of hindered classification and of the requirements for hindered settling in practice, a classifier has been developed that takes fullest practical advantage of the widely known, but generally only meagerly understood, condition of hindered settling so well analyzed a number of years ago by Dr. Richards.The present paper presents briefly some of the more important practical results accruing through the investigation."

Jun 1, 1924

By S. J. Broderick

[The discovery in 1934 that carbonaceous materials, such as coal, peat, and lignite, when treated with concentrated sulfuric acid, were given cation or bate-exchange properties opened up a field of new materials with many interesting possibilities. These hydrogen exchangers, as they were called, were so superior to the impractical hydrogen exchangers made from natural and synthetic zeolites tat they were accepted immediately by the water-conditioning industry. A noteworthy advantage of the carbonaceous exchangers is that they are nonsiliceous, hence they do not give up silica to the water as do the natural and synthetic Zeolites, especially if the hard water is corrosive. For this reason the new exchangers found immediate favor in boiler-feed-water conditioning.]

Jan 1, 1941

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

By K. C. Dean

The combination of flotation and chemical processing methods presented in this report of the Bureau of Mines enabled treatment of typical low-grade ferberite ores from the Boulder County, Colo. area, to produce specification-grade synthetic scheelite. The overall recovery from ore to synthetic scheelite was 87 percent, based on a flotation recovery of 93 percent and a similar recovery in chemical processing. Preliminary mineral dressing studies revealed that the physical and mineralogical nature of typical ferberite ores precluded high recovery of tungsten in plus 60-percent-W03-grade products by these methods. Therefore, the flotation research was focused on attaining plus 90-percent recovery in a concentrate containing 10 percent W03. Detailed studies were made (1) to establish optimum grinding conditions for obtaining adequate mineral liberation, (2) to develop collecting and modifying reagent combinations that would enable controllable selective flotation, and (3) to define the influence of different pulp solids, temperature, pH, and time for conditioning and for the rougher and cleaner flotation stages.

Jan 1, 1961

By James S. Browning

[The objective of this project wan to determine the technical feasibility of recovering the associated copper, lead, and zinc from the pyrrhotite axe, of the Great Gossan lead, which has bon pined only for it:, sulfur and iron contents so far. The report constituted a description and discussion of small-scale Preliminary studies. This great pyrrhotite or body has strategic value, inasmuch it contains considerable quantities of zinc, copper, and lead, as well as the iron rend sulfur. The recovery of the: copper, lead, and zinc, associated with certain of the pyrrhotite ore bodies, could augment our domestic supply of these metals.]

Jan 1, 1953

By R. T. Johansen

A gradual decrease in injection rates commonly occurs as a water-flooding project becomes older. This decrease can be attributed to changes in reservoir conditions, such as swelling of clay minerals, fillup, or gradual plugging of the sand face. However, a rapid decrease in the rate of injection indicates abnormal behavior and is cause for alarm. Extreme plugging conditions can completely stop injections into a formation. Such behavior in wells was the main concern of the tests described in this report. An accepted method of alleviating this condition is by backflowing input wells - closing the supply lines to the wells and allowing the reservoir pressure to force water back into the wellbore and to the surface. If backflowing is not successful, a string of smaller diameter pipe sometimes is run inside the casing, and the sand face is flushed with a waterspray. More drastic treatment is to inject acid into the wellbore to dissolve extraneous matter, or even part of the reservoir material, in an attempt to restore the permeability of the sand immediately around the wellbore. Any of these procedures can he coordinated with bailing and swabbing of the well for cleanout purposes.

Jan 1, 1957

By B. W. Jong

As part of the Bureau of Mines program to develop substitutes for critical and strategic materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives and starting materials on the sintering and strength properties of sialon (silicon-aluminum-oxynitride) compositions fabricated by conventional pressing and sintering techniques. Sintering and MOR (modulus of rupture) data were developed for sialon compositions produced from three components, Si3N4, A1203, and AIN. When doped with Y203 to aid in sintering, the highest MOR values were obtained with compositions containing between 20 and 30 mole-pet (A1203 + AIN). The effect of the crystalline phase of the Si3N4 and Al203 used in the three-component system on MOR also was investigated. Alpha-Si3N4 and ?-A1203 were found to be the best starting materials. A sialon composed of 67.4 mole-pct a-Si3N4 plus 32.6 mole-pct (?-AI203 + AIN), doped with 5 wt pct Y203, had MOR values at 25°, 1,200°, and 1,400° C of 40,300, 40,300, and 31,100 psi, respectively. Samples of this composition doped with Gd203, MgO, Zr02, and ZrSi04 also were evaluated. The ZrSi04-doped sialon had higher MOR values than Gd203-, MgO-, and Zr02-doped materials but lower MOR values than the Y203-doped sialon. The MOR values of ZrSi04-doped sialons were 25,000 and 25,900 psi, respectively, at 25° and 1,400° C.

Jan 1, 1981

By Jr. Smith

The equilibrium compositions of product gases for mixtures of air with methane, propane, or ethylene at and around flame temperatures are reported. For each hydrocarbon, compositions are given for five fuel-to-air ratios--two lean, two rich, and one stoichiometric--at five pressures, from 1 to 20 atmospheres, and at an ambient temperature of 25° C.

Jan 1, 1965

By S. P. Howell

"Technical statistical study has been made of accidents in the anthracite region of Pennsylvania in which explosives were involved. The data have been taken from the accident reports in the files of the department of mines of Pennsylvania, supplemented by inquiries in the field.This study has disclosed a wealth of information regarding the nature and the cause of accidents that occurred where different means of firing shots of explosives were employed. In the anthracite region shots are fired with fuse, with squibs, and with electricity,Many of the salient features of this accident experience are illustrated in this report of investigations, and a number of recommendations are made to reduce the hazards of each of these three methods of shot firing.Experience seems to demonstrate that, under conditions in the anthracite region, electric firing of shots is substantially the safest method; that accidents wherein fuse is employed are more frequent than accidents in which electric firing is employed; and that the number of accidents when squibs are employed far exceeds those in which either fuse or electric firing is used."

Mar 1, 1930

By J. E. Shelton

This presentation covers the results of laboratory studies conducted by the Bureau of Mines Mineral Dressing Section, Northwest Electrodevelopment Laboratory, Albany, Oreg., on alluvial sands from Dismal Swamp, Bear Valley, and Cascade, Idaho. The search for radioactive minerals has led to the reexamination of alluvial deposits; in the process of this reappraisal the frequent presence of minerals bearing columbium and/or tantalum was toted. Because of increased demand for these metals by the defense industries and because these industries depend upon foreign sources for their supply the domestic alluvial black sands are being considered, as a possible domestic source. However, utilization of these alluvial deposits depends upon development of methods of concentrating these valuable minerals. The primary objective of the test work was the study of the effect of attrition scrubbing, sizing, magnetic, electrostatic, and gravity separa¬tion as methods for concentrating and recovering the columbium and tantalum-bearing minerals, samarskite, euxenite, ilmenorutile, and columbite.

Jan 1, 1955

By William W. Adams

Reports for the calendar year 1923 that have been transmitted to the Bureau of Mines of the Department of the Interior by mine officials of the various coal-producing States show that accidents in and around the coal mines resulted in the death of 2,452 men. The output of coal during the year, as reported to the United States Geo- logical Survey, was 641,476,000 tons; hence the fatality rate per million tons was 3.82 as compared with 4.15 for 1922, a decline of about 8 per cent. The average rate for the decade ending with 1922 was 4.11. This reduction of 8 per cent in the fatal-accident rate per million tons is equivalent to the saving of 210 lives--that is, had the fatality rate of 1922 continued through 1923 the number of lives lost would have been 210 more than they actually were. Not only was there a net reduction in the fatality rate from all causes combined, but each of the main causes of coal-mine fatalities also showed a decline. Falls of roof and coal, which generally account for nearly half of all deaths in coal mines, were responsible for 1,158 fatalities in 1923, which represents a rate of 1.81 per million tons as compared with 1.90 in 1922. (See Table 2.) Haulage accidents underground usually cause about 17 per cent of all fatalities, and the reports for 1923 show that 413 deaths were due to this cause, indi- cating a rate of 0.64 per million tons, as against 0.71 for the previous year. Gas and dust explosions killed 372 men, the fatality rate being 0.58; the rate for 1922 was 0.65. Seventy-five deaths were due to electricity, for which class of accidents the fatality rate per million tons was 0.12 as compared with 0.16 the year before. Powder and other explosives caused 114 deaths, representing a rate of 0.18 as compared with 0.19 for 1922. Of the 2,452 fatal accidents during the year, 2,249 occurred under- ground, 46 in shafts, and 157 on the surface. At bituminous coal mines the number of deaths was 1,943, of which 1,816 were under- ground, 31 in shafts, and 96 on the surface. At the anthracite mines

Jan 1, 1923

By Sam S. Taylor

"INTRODUCTION This report deals with a comparatively simple application of some of the engineering principles involved in the evaluation, installation, and operation of air- or gas-injection projects and well-clean-out and repair methods to increase the producing rates of oil wells in partly depleted pools during the war. The methods suggested for developing gas-injection projects take into consideration that in general no new wells will be drilled because of wartime restrictions of equipment and manpower and that only existing wells and second-hand machinery will be used. Because air will be employed as the injection medium in secondary-recovery operations where natural gas is scarce and expensive, the disadvantages and hazards accompanying, its use are discussed. Engineering techniques recognized as best modern practice are discussed in relation to the effect of simple air-injection development of properties on postwar operations and Probable ultimate recovery of oil. The report is an introduction to where, when, why, and how an air-injection project should be installed and operated; it is not intended to be an engineering manual for technical guidance in the selection, development, and operation of simulative methods of oil recovery.The report is intended mainly for these thousands of operators in the Appalachian region owning a few wells prodding small quantities or oil daily. Many such operators are anxious to increase their production rates by simulative means and to rehabilitate their wells so that they will produce more oil to help win the war but, in general, are unfamiliar with secondary-recovery operations and cannot afford to hire technical assistance."

Sep 1, 1944

By S. J. Broderick

[The discovery in 1934 that carbonaceous materials, such as coal, peat, and lignite, when treated with concentrated sulfuric acid, were given cation or bate-exchange properties opened up a field of new materials with many interesting possibilities. These hydrogen exchangers, as they were called, were so superior to the impractical hydrogen exchangers made from natural and synthetic zeolites tat they were accepted immediately by the water-conditioning industry. A noteworthy advantage of the carbonaceous exchangers is that they are nonsiliceous, hence they do not give up silica to the water as do the natural and synthetic zeolites, especially if the hard water is corrosive. For this reason the new exchangers found immediate favor in boiler-feed-water conditioning.]

Jan 1, 1941

By Donald W. Ross

Petroleum oils of widely different grades have long been clarified or decolorized by contact with fuller's earths. More recently, so-called activated clays have also been used for this purpose. Still more recently ouch clays have been used in the form of nodules termed "catalytic pellets." Clays of varied appearance and from different localities possess the desired bleaching qualities, but evaluation of such clays, so useful to the oil industry, has not been simple. Previous methods of identification and evaluation have largely followed procedures of production methods and were not primarily based upon the fundamental properties of the clays. Thus) a false assumption has grown up that) bleaching clays probably have no common properties on which a-method of comparison can be based. Fuller's earths and activated clays have a large absorptive capacity for the color constituents of petroleum and its products decolorizing is accomplished by bringing the oil into intimate contact with the clay and later separating the decolorized oil from the clay with its load of absorbed coloring matter. Former practice in absorbing "color" was to use the clay as granules or In' powdered form. More recent practice is to use clay pellets that are more abrasion-resistant than the granules. The oil is either filtered through a bed of clay, percolation method, or agitated on contact with the clay, contact method. Viscous oils are decolorized at an elevated temperature, so that their viscosity is lowered to the point at which thorough contact with the clay is insured. Nonhumidifying, nonoxidizing gas, such as dry steam or dry nitrogen, is used to seal such hot oil masses from the atmosphere.

Jan 1, 1948

By Oliver Bowles

"INTRODUCTION Slate has earned a high reputation as a roofing material, carefully selected and properly placed it is rainproof, attractive, and extraordinarily durable. Despite there qualities in its favor, the slate industry during the past 30 years has suffered marked reduction in volume of sales. An increase in building construction and general improvement in business will doubtless bring renewed activity, but considerable ground has to be recovered before the industry can become prosperous. Influences tending to dwarf this long-established industry producing materials of world-wide reputation are analyzed briefly in the following pages in the hope that they may be rectified.HISTORY OF SLATE PRODUCTIONFigure 1 shows graphically the rise and fall from year to year of sales of roofing slate since 1885. In quantity, the peak was reached in 1902, and the most serious decline was from 1912 to 1918, sales at the end of this 6-year period being only one third those at the beginning. Unlike most building materials, slate experienced only a slight recovery in volume of sales during the post-war period, 1920-29. The value closely parallels the volume up to the World War period. Subsequently, however, as unit values increased the aggregate value rose sharololy above the volume curve, attaining in 1928 the point reached in 1903, although the Lumber of squares sold was scarcely one third as great. The increased unit value was due partly to larger sales of heavy architectural grades."

Nov 1, 1933

By James P. Bennett

The Bureau of Mines is investigating the acid resistance of ceramic materials to identify construction materials for emerging technology in chemical and metallurgical processes. Eight commercial ceramic materials, were evaluated: two red shale, two fireclay, one silicon carbide, one silica, one carbon, and one high-alumina. Samples were exposed to 10 wt pct H2S04 at 50° C and 10, 30, 50, 70, and 90 wt pct H2S04 at 90° C for time periods of 110 days. Statistically significant changes in cold crushing strength were observed in the silicon carbide and car-bon materials. Weight changes and the leach rate of Al, Ca. Fe. K, Mg, Na. Si, and Ti were also monitored. The most severe corrosion conditions were at 90° C and 30 to 50 wt pct H2S04 for the acidproof and at 10 wt pct H2S04 for the acid-resistant materials. The silica and the high-alumina materials were the most acid-resistant, followed by the higher density red shale and fireclay.

Jan 1, 1986

By G. Richards Gwinn

Vermiculites are secondary minerals formed by the: alteration of biotite and philogopite mica and are associated with basic rocks such as dunites, serpentines, and pyroxenites. Vermiculite was first described by T. H. Webb in 1824. It remained a mineralogical curiosity until 1913, when the first commercial deposit was discovered in the Turrett mining district of Colorado. Expanded or exfoliated vermiculite was first marketed in 1915 from a deposit in this district 5 miles southeast of Hecla, Colo. This activity was brief, but successful and continuous commercial development began in 1921 in Montana. 'Deposits in other States have been found and developed, but Montana is by far the largest producer. Vermiculite has also been found in South Africa, Western

Jan 1, 1944

By Walter I. Enderlin

To economically extract ore from great depths in the earth while sustaining an acceptable working environment will require the development of new technology and equipment, involving large capital expenditures. Moreover, careful analysis and advance planning will be required. But, the literature is lacking in data pertaining; to the thermal properties of various host rocks and to quantities of heat generated by various underground heat sources. This types, of data is required to forecast nine heat loads during advanced planning and design. This thesis sets forth a practical method for evaluating underground sources of heat in deep mines and provides an improved information base. Moreover, seven topics for further research are recommended. The heat sources considered are: wall-rock, ground water, adiabatic compression, equipment, service lines, blasting, metabolism, curing of cement, and oxidation of sulfides and timber. Seven deep metal mines with high production rates and high heat loads were visited to obtain data necessary to assess their thermal environments. Mine records were examined, wall-roc:, temperatures were measured and a survey of the mine ventilating air and mine drainage was performed. Also, the thermal conductivity of wet and dry specimens of the host rock were measured in the laboratory. Data analysis disclosed that rock heat and adiabatic compression account for stout 60 per cent of the mine heat load at depth. Equipment currently contributes approximately 20 per cent; however, to offset increasing costs with depth, increased mechanization is anticipated. The treat from ground water averages 19 per cent and the contribution from blasting, metabolism and cement is negligible. Also, approximately [0] per cent of the increase in the enthalpy of the ventilation air is in the form of latent heat. Moisture, however, did not significantly affect the thermal conductivity of the rock specimens measured in the laboratory. Also, from the data, it is evident that a negative correlation exists between the thermal conductivity of the host rocks and the per cent of the heat load derived from the wail-rock. Furthemore, steady state heat flow renditions may be assumed in airways where there has been no major changes in the ventilation system for a period of two years or more. Under these conditions, the author found it more convenient and reliable to compute heat influx using the steady state equation for heat flow into a cylinder, rather than Carrier's method for transient heat flow, which is so often used.

Jan 1, 1973

By Arthur J. Hudson, Lawrence W. Scott

The performance of RETIMET metal foam as a flame arrester on explosion-proof enclosures was investigated by the U.S. Bureau of Mines both in laboratory tests and at the U.S. Mine Safety and Health Administration's (MSHA's) Approval and Certification Center, Triadelphia, WV. The objective of this research was to develop a permissible pressure vent for use on lightweight, vented, explosion- proof enclosures. In laboratory tests, four grades of RETIMET, a stainless steel foam material, were evaluated: (1) 45 NC-7, (2) 45 NC-13, (3) 80 NC-7, and (4) 80 NC-13. Explosive gas mixtures were prepared by a dynamic flow system. Ignition was by a low-voltage arc. Each grade of RETIMET metal foam successfully arrested the flame front in all methane-air tests. To evaluate RETIMET metal foam on large, commercial size enclosures, a multicompartmented enclosure was designed and tested in MSHA's explosion gallery in Triadelphia, WV. Extensive explosion testing revealed that a minimum vent-area-to-enclosure-volume ratio of 11.33 in2/ft3 is required to keep internal pressure rises below 3 psig. The RETIMET metal foam functioned satisfactorily in all tests as evidenced by the absence of external ignitions.

Jan 1, 1992

By A. E. Gooch

The Bureau of Mines conducted research in an attempt to provide a more sound basis for recommending improved artificial support during deepening of the main shaft of the Lucky Friday mine in the Coeur d'Alene mining district of northern Idaho. Field measurements of closure across the short axis of the 13-by 26-foot shaft were as high as 16 inches. Elastic/plastic finite-element (F/E) analyses were made, reducing the values of large-scale in situ rock mass properties until field closure measurements generally corresponded to displacements in the F/E analyses. Resulting plots of rock mass displacements, stresses, and areas of plastic failure display the results of creating openings (shaft, in this case) in deep mines in difficult ground conditions requiring artificial support.

Jan 1, 1976