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By J. W. Paul

This circular is one of a series of papers4 on coal-mining methods and costs which are being prepared through the sponsorship of the U. S. Bureau of Mines for the purpose of presenting information on present mining methods and certain features which govern costs, safety, and conservation. The methods employed are influenced by natural local conditions with respect to the thickness, character, and dip of the coal bed, the nature of the roof and thickness of the overbearing strata, and the means employed for roof support and its control.

Jan 1, 1929

By J. E. Gebhardt

External control of the electrochemical potential of a bed of mineral particles has been investigated by the Bureau of Mines as a method for controlling particle inter-action with organic collectors and thus, flotation response. A cylindrically shaped, 200-to 300-g bed of sulfide mineral particles was used as the working electrode to examine the potential distribution in the bed. The dissolved oxygen concentration of the electrolyte had a significant effect on the potential profile across the mineral bed. Low oxygen levels were necessary to achieve uniform electrochemical potential distributions. Flotation separation of a chalcocite-pyrite mineral mixture by controlled potential was achieved using ethylxanthate, but the flotation behavior of chalcocite and pyrite from the mixture does not follow the flotation behavior of the individual minerals. That is, the presence of another sulfide mineral alters the flotation behavior with ethylxan-thate. Galvanic interaction due to mineral-to-mineral contact between chalcocite and pyrite contributes to differences in the recovery. Chalcocite dissolution products had a deleterious effect on pyrite flotation by activating flotation below -0.1 V (saturated calomel electrode) and depressing flotation above -0.1 V. Pyrite dissolution products had no effect on chalcocite flotation.

Jan 1, 1985

By R. M. Santmyers

Umber and sienna, like ocher, are naturally occurring mineral pig- ments composed largely of clay permeated with hydrated iron (ferric oxide), but they differ from ocher in that they also contain hydrated manganese oxide. The presence of manganese accounts for their browner color. In addition to silica and alumina (clay) and the coloring oxides of iron and manganese, these pigments often contain lime, barium, and other metallic salts as impurities. Sienna most nearly approaches ocher in chemical composition, and the chief distinction is its physical character. It grades into ocher with de- creasing iron content and into umber with increasing manganese content. Sienna is translucent rather than opaque and is more of a stain than a pigment; as the iron oxide content is rather high (often 60 to 80 per cent), the color is strong and rich and varies from pure brown to reddish brown. This pigment raw sienna, terra di Siena, and Italian earth. is known under several names: Burnt sienna is a pigment of an orange-brown tint made by cautionsly calcining raw sienna. It is divided into two grades; American, and Italian burnt sienna. American burnt sienna is a reddish-brown pigment containing from 25 to 60 per cent iron oxide (Fe2O3). One grade, found in Pennsylvania, analyses as high as 80 per cent and is mown as double strength sienna. Italian burnt sienna is a pigment generally containing more iron than the American product, averaging 60 to 75 per cent iron oxide.3 American pig- ments of the same iron content differ materially in shade, having a Havana- brown color, whereas the Italian is more of a maroon. Italian siennas when tinted with 20 per cent of white, show a bluish tint, whereas American siennas yield a brownish or yellowish hue. Raw umber, also known as Turkey umber, Levant umber, and terra ombra, is a greenish to yellowish brown siliceous and ferruginous earth, containing a considerable proportion of one or other of the higher oxides of manganese, Mng04 and MnO2." It is similar in many respects to raw sienna except that it is much coarser and contains more manganese oxide. All umbers contain over 5 per cent of manganese dioxide. Like sienna, umber is a permanent pigment, not being injured by light or by impure atmospheres. Burnt umber (velvet brown, chestnut brown, etc.), results from the calcination of raw umber. The color is much richer and warmer than that of the raw umber. The colors are equally permanent and can be used in conjunc- tion with all other durable pigments.

Sep 1, 1931

By H. M. Lawrence

"Florida, the State that supplied 82 per cent of the phosphate rock sold in the United. States in 19284, has two producing areas - the hard-rock and the land pebble districts. Production of the hard-rock field, decreasing importance in recent years, is now confined to mines near Dunnellon, in Marion and. Citrus Counties. The land-pebble district, with a production of almost 80 per coat of the nation's requirements, is located, in Polk and Hillsborough Counties. In the land-pebble area the phosphate deposits - probably Pliocene in age, derived by marine action from underlying, older, phosphate-bearing formations - consist of beds of phosphate matrix, covered by practically barren sands and clays. The overburden, ranging in thickness up to 45 feet, is removed by hydraulic methods or by drag-line excavators. The matrix, ordinarily less than 25 feet in thickness, is mined by hydraulicking and is pumped to adjacent washing plants for beneficiation. The dried product of the washing plants is the Florida pebble rock that is sold in foreign as well as domestic markets.The beneficiation of phosphate ores in the land-pebble district of Florida has been largely limited in the past to the recovery of the coarser pebbles. By washing and screening the crude matrix a separation is effected at about 20 mesh (0.033 inch). The coarser material is the phosphate-rock product of the plant and the finer material is discarded. The amenability of the washer- rejects to treatment by other processes is being investigated. Of methods that may have some application to the treatment of the low-grade phosphatic sands that comprise the greater portion of the washer-rejects, gravity concentration has received some study.Laboratory experiments to determine the amenability of phosphate sands to gravity methods of concentration were first performed in October, 1927. Later, in the winter of 1928-1929, a further series of teats was made,. In these later tests phosphatic sands were concentrated by hydraulic classification, and. also by hydraulic classification followed by tabling. In these experiments concentrates with an analysis above the minimum grade of commercial phosphate rock (66 per cent bone phosphate of lime - B.P.L.) obtained. The recovery of the phosphate varied but was promising enough to warrant further study. A more comprehensive investigation was therefore outlined. This paper presents the results obtained from an investigation, of classification and tabling of phosphatic sands recently completed by the United States Bureau of Mines Su cooperation with certain Florida phosphate companies, the Missouri School of Mines and Metallurgy, and the University of Alabama."

Jul 1, 1930

Research 86 highlights significant studies conducted during the past fiscal year at Bureau facilities and offices. Readers who want more information about the projects and studies summarized here can contact the researchers whose names and locations appear with each summary. General information on Bureau of Mines programs is available from the Office of Technical Information 2401 E Street, NW., Washington, DC 20241. A listing of principal officials, a location map of field facilities, and a selected bibliography of publications and patents issued on Bureau developments during the past 3 years are provided.

Jan 1, 1986

By J. E. Pahlman

As part of its effort to reduce the need for strategic minerals through conservation and to reduce the capital and energy requirements of mineral processing, the Bureau of Mines has investigated a method for preparing ferrochromium alloys containing less than 2 percent carbon. This method will conserve chromium and should reduce the capital and energy requirements for chromite reduction. Reduced products containing less than 2 wt-pct C and as low as 0.01 wt-pct C were obtained by reacting pellets of chromite and carbonaceous reductant mixtures at pressures of 0.1 to 1 torr and temperatures of 1,230° to 1,320° C. The extent of reduction increased with increased temperature and decreased pressure; however, operating conditions were limited due to the onset of significant chromium vaporization at higher temperatures and lower pressures. Foundry coke, anthracite, and carbon black were found to be supe¬rior to graphite as reductants. The reduction of chromite to metallics was found to proceed via the carbide intermediates (Fe,Cr)7C3 and (Fe,Cr)23C6, No evidence of carbide intermediates Fe3C or Cr3C2 was found. Buttons of ferrochrome alloys were made by melting a mixture of reduced products with CaO and Si02 at 1,700° C for 20 minutes in an induction furnace,

Jan 1, 1980

By William O. Vanderburg

Some mines after passing through the prospecting stage and becoming sizable enterprises still adhere to the development program of the prospect, extending their workings without definite plans. In mining operations where definite structural conditions do not exist, a prearranged layout of mine development is not feasible; but where exploration and preliminary development have indicated the extent and probable limits within which the ore is expected, careful planning of development will result in a lowering of mining costs and a consequent increase is profits. A lack of definite plane for laying out mine workings is one of the contributory factors to unnecessarily high costs. Although this paper deals primarily with the influence of level spacing on mining costs, still other phases of mine development, such as the proper spacing of ore chutes and raises, can be analyzed on a cost basis in a similar manner, as shown herein. LEVEL SPACING The problem of establishing a new level or levels in order to exploit steeply dioping ore deposits and prospect the ground at depth recurs at intervals during the active life of mines. Driving levels is largely "dead work" and therefore costly. By the judicious selection of the proper level interval after balancing the opposing factors involved in the problem, a considerable saving in mining costs can be effected. Although much has been written in regard to the various methods employed in ore extraction, mining literature is still incomplete in regard to the factors-influencing level spacing at various mines. Level spacing involves procedures not lending themselves readily to description, and, moreover, it is a phase of mining operations that is apt to escape criticism, because only those in close contact with the operations are equipped with the necessary familiarity with the conditions to pass judgment.

Jan 1, 1932

By Edwin C. Reeder

This paper, describing milling methods and costs at the Hillside Fluorspar Mines at Rosiclare, Ill., is one of a series being prepared for and published by the United States Bureau of Mines on non-metallic milling methods. The milling practice described is that of one of the large mines in the Kentucky-Illinois fluorspar field in southern Illinois and western Kentucky, on the Ohio River. Milling methods throughout the district are similar in their general principles, although details vary considerably in different plants.

Jan 1, 1932

By J. Wade Watkins

One potential peaceful application of nuclear explosives is stimulating the production of liquid or gaseous hydrocarbons from essentially nonproductive deposits of petroleum, natural gas, oil shale, and tar sands. Within the United States the appreciable difference between producible proved reserves and ultimate reserves and resources of hydrocarbon deposits is of such magnitude that much petroleum, natural gas, shale oil, and bitumen will not be produced unless significant technological progress is made in production techniques. The shattering effect of contained nuclear explosives and, to a lesser extent, the heat produced, have been considered as stimulative forces when the thickness, depth, and nature of such deposits permit considering the use of nuclear devices. Mechanical production problems would be less in an oil or gas reservoir than in an oil-shale or tar-sands deposit. Also, tar-sands resources in the United States may not be adequate to warrant serious consideration of applying nuclear-explosives stimulation. Gas reservoirs should present the least-radioactive-contamination problem. The technical feasibility of using nuclear explosives cannot be evaluated fully at present. Additional information is needed on the effects of pressure, heat, and radioactivity on the solids and fluids of hydrocarbon deposits, the nature and extent of induced fractures in different rock media, and the possibility of isolating and confining or removing radioactive contaminants. Final technical feasibility can only be determined by a field test. If technical feasibility is established, economic feasibility will depend upon the comparative cost of producing hydrocarbons by nuclear explosives and by conventional means. It is probable that an economic comparison would favor nuclear stimulation only where devices of relatively high yield could be used practicably and safely.

Jan 1, 1964

By Warren Hastings

This paper describes the methods and costs, in units of labor end materials, of sinking a 7 compartment vertical shaft 1,261 feet through a fractured, water-saturated formation. The shaft, designed for hoisting 2,500 tons a day, is at Friedensville, Lehigh County, Pa., approximately 6 miles south of Allentown and Bethlehem. It was sunk by the E. J. Longyear Co. under contract to the New Jersey Zinc Co. Preparation for shaft sinking W8A begun July 1, 1947, and sinking was completed August 18, 1952. A total of 604,858 man hours was required to sink the shaft.

Jan 1, 1954

By G. L. Anderson

The critical importance of wire rope integrity to the mining industry has led to the creation of standards for the retirement of wire rope as well as to the development of electromagnetic devices and procedures that would allow wire ropes to be tested against these standards without destroying them, The U.S. Bureau of Mines (USBM) conducted research to evaluate these devices by measuring loss of metallic cross-sectional area and the number of wire breaks, or local faults. The intent was to define the extent to which the technique can identify degradation within the rope, e.g., broken wires, corrosion, and wear. Experimental results showed that instrument sensitivity depended on a number of factors, including rope diameter, placement of sensors, location and characteristics of flaws, rope speed, and tension on the rope. The experiments also demonstrated the importance of having an elongated recorder trace and a properly trained and experienced operator to interpret overall results. A design of a rope and test procedures for use in laboratory evaluation of instruments have been recommended by the American Society for Testing and Materials Committee E07.07.10, Wire Rope Applications. The USBM is working through this committee to develop standards for an electro-magnetic method of wire rope inspection.

Jan 1, 2010

By Paul M. Tyler

Masurium and rhenium are two elements known only to a few scientists and known to them for scarcely more than five years . The existence of two members of the manganese family was long suspected , and places were left for them in the orderly table of the periodic systemas developed by Mendeljeeff . The empty spaces left in this table some 60 years ago were for elements numbered 43 and 75 , respectively , and since it was evident these were related to manganese they were sought for in research laboratories under the names of ekamanganese and dvimanganese . This nomenclature is in harmony with that usually employed in describing hypothetical elements , and the prefixes are taken descriptively from ancient Sanskrit wherein the word " eka " means one and " dvi " ( also spelled dui or dwi ) means two . Ekamanganese or element 43 was once removed and dvimanganese or element 75 was twice removed from manganese . It was further possible to predict that these elusive elements would not only be related to manganese but would have a great deal in common with certain other elements . It was reasonable to suppose that element 43 , merely because it stood in numerical sequence between element 42 and element 44 , would likewise prove to be intermediate in many other respects . Since its next neighbors were molybdenum ( No. 42 ) on the one hand and ruthenium (No. 44) on the other , ekamanganese could be given in advance what would correspond among persons to a social and economic rating . Similarly , the properties of dvimanganese were likely to be in simple harmony with those of tungsten and with those of osmium , which latter , like ruthenium , is a member of the platinum group of metals . Another inference , although one which could not be stated with scientific certainty , is that these new elements because they have odd instead of even atomic numbers , would be even more sparingly distributed than their near neighbors , none of which is abundant in nature . This inference has been amply supported by available evidence . These elements eluded discovery until 1925 and never have been found except as minute traces in complex association with relatively rare minerals . In 1930 , for the first time , rhenium became available in quantities which give promise of commercial possibilities , but masurium still stands on the border of the unknown , like some distant star speck photographed and identified by vigilant astronomers but invisible without the aid of the powerful tools of science . The telltale flame of element 43 has been charted by its spectrum lines ; but beyond that , little more can be said except perhaps to repeat the forecasts made for ekamanganese before the Noddacks captured it and gave it a definite name . Certain rare - mineral dealers will furnish molybdenite samples from Norway which are said to contain masurium as well as rhenium , but except for a few highly technical statements as to its behavior in the spectrograph , nothing in the way of concrete information on masurium has come to the notice of the present writer . The literature of rhenium is a little less meager and a brief résumé of the data available in the files of the Bureau of Mines may be of interest not merely because of the novelty of the metal but because its unique properties and increasing availability afford a prospect of its finding employment in industry .

Jul 1, 1931

By Herbert R. Babitzke

As part of a project to develop refractory metal alloys suitable for high-temperature structural applications, the Bureau of Mines applied solid solution and precipitation-hardening techniques to columbium and tantalum alloys. Thirty-three alloys were evaluated to determine their formability, strength, and oxidation resistance. Three alloys had tensile strengths near 40,000 psi at 1,200° C: Cb-1N-5W-5V-10Hf (No.4), Cb-15Hf-5W-0.5B (No. 31), and Cb-15Hf-SW-IB (No. 32). Oxidation resistance of the high-strength alloys was good. Alloy4 gained only 34 mg/cm2 at 1,200° C, and 21 mg/cm2 at 1,000° C in 2 hours. Hot forming was done without any protection from oxidation.

Jan 1, 1968

By S. H. Ash

The United States Bureau of Mines has published relatively little on the flooding and unwatering of coal and metal mines. Bulletin 229, Fifty-Nine Coal-Mine Fires, published in 1927, contains several instances of the flooding of mines or sections thereof to extinguish fires but does not describe their unwatering. Report of Investigations 2649, Explosion Hazards Incidental to Unwatering Coal Mines, published in 1924, warned against the possibility of gas accumulations in flooded mines and indicated the precautions to be taken. Report of Investigations 2255, An Unusual Hazard in Reopening Long-Flooded Timbered Metal Mines, published in 1921, told of methane being pocketed and the danger thereof. The flooding of mines originates in many ways. At some mines flooding followed reopening after what was thought to be permanent abandonment; also, explosions have caused some mines to be flooded. Extinguishing fires, accidental encountering of underground streams or flooded old workings, and caves of strata admitting water from underground workings, water-bearing strata, or surface accumulations have also flooded all or parts of mines. Unfortunately, un watering often necessitates much study and causes apprehension largely because experiences in similar situations are not generally known, as few descriptions of successful or unsuccessful methods are available. The job has sometimes been contracted for outside the local management involved and has become a matter of record for the contractor only. As the cost-plus contract system often employed in the past is now known to be expensive, careful managements elect to handle the problem themselves, in line with the general policy of cutting expense where possible. This report describes specific in-stances of successful unwatering by operators.

Jan 1, 1933

By R. E. Stiles

The modified perchloric--EDTA method devised by the Bureau of Mines for the determination of copper in high-grade samples gives results that are more precise and more accurate than those from the classical sulfuric-iodometric method. Although the perchloric--EDTA method is more costly than the conventional method, the savings in time alone largely offsets this difference. Specifically, the modifications wade in the more conventional procedure comprise (1) use of perchloric acid instead of sulfuric acid for dissolution of copper minerals, (2) precipitation of copper as copper sulfide from dilute perchloric acid solution, (3) wet oxidation and dissolution of the precipitated copper sulfide, (4) use of larger amounts of indicator than those employed in the Schwarzenbach method of titrating low-tenor copper solutions with disodium ethylenedinitri10-tetraacetate and murexide indicator, and (5) use of refrigeration to partially stabilize aqueous solutions of the indicator.

Jan 1, 1966

By W. R. Hardwick

Nuclear explosive fracturing has been suggested as a method to make hard rock amenable to extraction by a modified block-caving method. To evaluate this possibility, conventional and nuclear blasting practices are discussed, underground mining methods for large deposits and their costs are described, and the cost of fracturing ore with a nuclear explosive and subsequent mining by a modified caving system is estimated and compared with both open-stope and block-caving mining costs. While the direct cost of fracturing the ore in hard rock with a nuclear explosive is less than with conventional explosives, additional costs imposed by the use of nuclear explosives may make their use unattractive for deep mining.

Jan 1, 1970

By E. C. Tarpley, R. A. Drogowski, R. F. Abernethy

Three of the test methods frequently used for the determination of moisture in the analysis sample of coal were employed in analyzing a series of coals ranging in rank from anthracite to lignite . For most coals , the variation between the three methods are within the tolerances allowed between duplicate determinations by the same method . The processing variables studied included atmosphere , flow rate of atmosphere , inert atmospheres , oven temperatures , heating time , exposure of the dried coal to laboratory air , and surface area of the test sample . Unless close control is kept on these variables , erratic results will be obtained .

Jan 1, 1964

Volume 2 presents the results of studies of Phelps Dodge Corporation's tailings embankments numbers 1West and 2 West, at Morenci, Ariz. The work involved compilation and description of pertinent factors relating to the physical features and operational characteristics of the facility, including information on embankment construction practices; investigation and research of the general geologic and seismicity characteristics of the site and vicinity; limited field exploration and materials sampling and testing at the site; installation and limited monitoring of piezometers, surface movement markers, and slope indicator casing; limited laboratory testing of materials to evaluate the basic index and engineering properties of the embankment and tailings materials; selected engineering analyses of the embankment for various types of potential "failure" conditions; and includes appendices.

Jan 1, 1974

By Susanne Hering, Brent Kirby, Charles D. Litton, Tracy Allen, Kirk R. Smith, Rufus Edwards

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 µm) and fine (mass median diameter, 0.27-0.42 µm) size distributions (average r2 = 0.997 ± 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.

By C. C. Merrill

Columbium, tantalum, titanium, and zirconium are present in solid waste products generated by the chlorination of rutile used for production of titanium tetrachloride (TiC14). The columbium and tantalum were separated from titanium and zirconium by liquid-liquid extraction techniques using a secondary amine. Salts of these elements are in a leach liquor produced by water leaching of mineral waste from the chlorination of rutile. This waste, produced at the rate of approximately 50,000 tons per year, is about 40 wt pct water soluble. Leach liquors, separated by filtration, were further separated into a solid fraction and a liquid fraction by pressure hydrolysis, The solid fraction containing Cb, Ta, Ti, and Zr was dissolved in HC1-HF and used as a feed solution. Columbium and tantalum were removed from the organic extractant with 1 [N] HC1. A miniature 10-stage reactor showed that the columbium and tantalum present in solution could be separated with a continuous flow.

Jan 1, 1972