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By Seth C. Schaefer

The Bureau of Mines studied the standard free energies2 of formation of ferrous fluoride (FeF2) and ferric fluoride (FeF3) with high-temperature galvanic cells employing calcium fluoride doped with 1 mole-pet yttrium fluoride as the electrolyte. A free-energy change for the cell reaction Fe (s) + NiF2 (S) = FeF2 (S) + Ni (s) together with the standard free energy of formation of nickel fluoride yields a standard free energy of formation of ferrous fluoride from the elements of ?GF° = -168.74 + 30.63 x 10-3T ± 0.41 kcal/mole (897-1,098 K). (2) Combining the standard free energies of formation of magnesium fluoride, ferric oxide, and magnesium oxide with the free-energy change for the overall cell reaction 3MgO(s) + 2FeF3 (s) = 3MgF2 (S) + Fe2 03 (S) (3) gives a standard free energy of formation of ferric fluoride from the elements as ?Gf° = -281.45 + 90.46 X 10-3T ± 0,67 kcal/mole (880-935 K). (4) Free energies and equilibrium fluorine pressures for the two univariant equilibria of the Fe-F system are tabulated and illustrated.

Jan 1, 1975

By B. W. Gandrud

[The meaning of the term "bauxite' has always been somewhat vague and indefinite, and the term has been used in various applications to denote sometimes a rock, sometimes a mineral, but more frequently an ore. It seems logical to think of bauxite as an ore, however, because a very large part (probably at least 85 per cent) of the entire world's production of bauxite is at present being used as a source of aluminum and aluminum chemicals. In the United States there are two districts that, produce bauxite - the Arkansas district and the Alabama-Georgia-Tennessee-Mississippi district. The deposits in Mississippi have been discovered recently and are riot as yet productive but it seems reasonable to consider them as apart of the-district hat includes the deposits of Alabama, Georgia, and Tennessee. The, two districts are often referred to as the Arkansas field and the Appalachian field. Of these two the Arkansas field has been by far the largest producer, and at present over 90 per cent of the bauxite production of they United States comes from the Arkansas field. The bauxite industry in the Appalachian field had its beginning in 1889, and since that time the total production of the states of Alabama, Georgia, and Tennessee has been, nearly a million tons. The production of bauxite in this field has languished in the last five, or six, years, and In 1927 its production was only about 14,000 tons, according to Harder4. The recent decrease in production is due mainly to the fact that many .of the known deposits of commercial-grade ore have become exhausted. There are, however, considerable quantities of low-grade bauxite in the Appalachian field, but these have not been available because there has been no satisfactory way of concentrating low-grade bauxite. The quantity, of low-grade material in the Appalachian field is probably, fully as large as the tonnage of commercial ore which the field has already produced.]

Jan 1, 1928

By Ronald D. Hill, Elmore C. Grim

The removal of overburden often exposes pyritic materials (iron disulfide). As shown in equations 1 and 2, the oxidation of this material results in the production of ferrous iron and sulfuric acid. The reaction then proceeds to form ferric hydroxide and more acid, as shown in equations 2 and 4. [ ] Consequently a low pH water is produced (pH 2-4.5). At these pH levels, the heavy metals such as iron, manganese, copper, and zinc are more soluble and enter into the solution to further pollute the water. Water of this type supports only limited water flora, such as acid-tolerant molds and algae; it will not support fish life, destroys and corrodes metal piers, culverts, barges, etc., increases the cost of water treatment for power plants and municipal water supplies, and leaves the water unacceptable for recreational uses. The amount, and rate of acid formation, and the quality of water discharged are a function of the amount and type of pyrite in the overburden and coal, time of exposure, characteristics of the overburden, and amount of available water(l). Crystalline forms of pyritic material are less subject to weathering and oxidation than amorphic forms. Since oxidation by oxygen is the primary reaction during early acid formation, the less time pyritic material is exposed to air, the less acid is formed. Thus, a positive preventative method is to cover pyritic materials as soon as possible with earth, which serves as an oxygen barrier. In terms of mining, this step is accomplished by current reclamation techniques and small open pits.

Jan 1, 1974

By L. J. Froisland

The U.S. Bureau of Mines conducted laboratory studies on sulfuric acid (H2S04) digestion of alunite [KA13(S04)2(OH)6] as a means for treating domestic deposits of this mineral. Digesting alunite ore in boiling H2S04 at concentrations of 88-wt-pct acid or higher breaks down the alunite and permits a convenient separation of potassium and aluminum. The digestion reaction is a complex sulfation reaction occurring in two stages. In this reaction, the potassium component extracts into the H2S04 for eventual recovery as potassium sulfate k2s04 in a separate unit operation. Aluminum is left as acid-insoluble aluminum sulfate [A12(S04)a], which can be extracted by a 95° C water leach. Additional purification of AI2(S04)a produced in this study is needed to meet cell-grade alumina (Al202) purity specifications. Extraction and separation of potassium and aluminum from the alunite ore were consistently above 90 pct.

Jan 1, 1989

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

9. Remote Sealing System Sensitivity 9. 1 Introduction In the previous sections a description of the overall system has been presented along with detailed descriptions of the equipment and techniques employed with the preliminary probing system, the seal em¬placement system and the seal checking system. In addition, the use of these subsystems in a specific mine application has been described in considerable detail. A broad range of parameters of interest was specified in the contract, as summarized in Section 1. 3. Most of these are a function of the general location; i. e. , the location of the mine, and the specific location; i. e. , the location of the boreholes. These parameters of interest include passage size, shape, depth, slope and water con¬ditions. The length, diameter and location of the boreholes within the mine passage and on the surface are critical parameters as well. A few additional parameters may affect one or more of the remote sealing subsystems. These include temperature, topography, rock and soil conditions, and underground water. While variation in these parameters will not render the system inoperative, consideration of them in the planning stages will simplify and expedite the field operation. In the following sections the effect of the various parameters on the remote sealing operation will be discussed. For clarity, the several tasks, borehole drilling and casing, preliminary probing, fly ash delivery, foam topping and seal checking, will each be considered separately.

Jan 1, 1973

By T. H. Jeffers

Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible spent copper leach solutions. For example, recovery of cobalt at two major u.S. copper operations could produce about 1,300,000 lb Co annually, about 13 pct of domestic consumption. However, techniques such as solvent extraction and precipitation have not proven cost effective in separating and recovering the cobalt from these low-grade domestic sources. The Bureau of Mines has devised a procedure using a chelating ion-exchange resin to extract cobalt from a pH 3.0 copper leach solution containing 30 mg/L Co. Cyclic tests in 4-ft-high by 1-in-diam columns gave an average cobalt extraction of 95 pct when 65 bed volumes of solu-tion were processed at a flow rate of 4 gpm/ft2 of resin area. After an impurity scrub, eluates contained, in grams per liter, 0.4 Co, 0.2 Ni, <0.001 Cu, 1.3 Fe, 2.8 Zn, and 0.008 AI. Solvent extraction procedures to remove impurities, reject nickel, and concentrate cobalt produced a cobalt sulfate solution containing 80 g/L Co, 0.05 g/L Ni, and not more than 1 mg/L Cu, Fe, Zn, or AI. Based on data from commercial electro-winning operations, this solution appears suitable for production of metallic cobalt.

Jan 1, 1985

By Marvin L. Whisman

A radiotracer technique developed by the Bureau of Mines extends to the parts-per-billion range the sensitivity for determining contributors of deposits formed in stored and thermally stressed jet fuels. The method depends upon measuring radioactivity associated with thermally induced deposits from fuels containing one labeled compound. The technique was applied to 88 test blends, representing 12 fuels and nine carbon-l4 labeled fuel constituents or fuel additives, or both. Data from results of these tests are included in this report. With this radiotracer technique, the contribution of fuel components and additives to thermally induced deposits in a variety of fuel environments was estimated before and after storage.

Jan 1, 1969

By Charles L. Kimbell

Annual global steel industry investment is partly mirrored in the data for selected market economy countries that appear in table 13 for 1988-90. No reasonably comprehensive 1991 data were available for inclusion in this study, and the partial reporting available was so incomplete that it was impossible to demonstrate whether the level advanced or declined from the 1990 level of nearly $15.5 billion. Moreover, with the radical changes that are now being effected in the steel industries of the states that were the U.S.S.R. and its CMEA partners, it is most regrettable that comprehensive and comparable data, both current and historic, on investment in this area are not available. Updated information on market economy country petroleum industry capital and exploration expenditures by geographic area has been included in table 14, and it is evident that there was a substantial upturn in investment in 1991. The level of almost $74.5 billion was 14.5 % above the 1990 level and included gains in every topical category and geographic area. The source of information for this table has been changed to the Oil and Gas Journal Database from the previously used Chase-Manhattan Bank study of Capital Investments of the World Petroleum Industry, which has been discontinued. Because of this source change, it has been necessary to modify the structure of the table somewhat, but its total scope of coverage is regarded as basically unchanged. It should be noted that the grand total, as well as some of the detail appearing for 1987, corresponds precisely with those in the previous source.

Jan 1, 1993

Reduce methane levels around the shearer machine during longwall mining by directing more of the available airflow along the face and over the shearer body. Approach To address the entire mining cycle, two techniques were combined to dilute and clear the methane liberated from the face by the shearer during cutting. The first is the modified shearer clearer system, which is used during the entire face pass. This is combined with the walkway curtain which is used only during the headgate cutout. How It Works Methane ignitions are one of the most potentially serious hazards facing longwall mine operators. The high rate of coal extraction on longwall sections can liberate a significant quantity of methane during a pass. The modified shearer clearer is used to dilute methane concentrations along the entire face for both cut directions. The shearer clearer system, originally designed as a dust control technique, uses a series of water sprays located on the shearer body to direct more airflow along the face and over the shearer. (See Technology News issues, #112, #118, and #221). The only change from the original shearer clearer design is the addition of three sprays to the return-side splitter-arm/ shearer interface. The additional sprays help to ventilate the area behind the shearer body.

Jan 1, 1985

This Information Circular from the National Institute for Occupational Safety and Health (NIOSH) documents and supplements the information presented in a series of workshops held during 2002 and 2003. The primary intended audience consists of all who are involved in developing and conducting miners? training. According to the Mine Safety and Health Administration (MSHA), mine operators reported 240,000 full-time equivalent workers and independent contractors reported 42,000 full-time equivalent workers working on mine property during the year 2000. Unfortunately, these workers have a relatively high risk of suffering serious work-related injuries and illnesses. The mining industry has the highest rate of occupational fatalities among all U.S. industries. The fatality rate is 30 deaths per 100,000 workers compared to 4.6 for all private industry(Morbidity and Mortality Week Report, 2001; NIOSH, 2002).Compared to workers in other industries, miners also have a relatively high rate of nonfatal lost-time injuries, and their injuries tend to be more severe (Bureau of Labor Statistics, 1999). Many miners are also exposed to significant health hazards, including coal and silica dust, diesel exhaust, and noise. More than 1000 U.S. miners die of lung disease each year(NIOSH, 1999).

Jan 1, 2002

By James E. Hill

TECHNOLOGY is best nurtured by a sympathetic climate that is a composite of many factors. Necessity is a highly motivating factor as illustrated by the abnormal surge of technologic development curing wartime. Other factors include appropriate timing, economic pressures, available personnel, and in some instances, legislative action. Problems of recent concern to mining technology have been the quality and quantity of available technical personnel and the possibilities of restrictive legislation. The quality and quantity of technically trained personnel may be inadequate to meet the rapidly increasing complexity of modern technology coupled with the growing demand for qualified personnel. The question of appropriate training was a subject for debate.2 The curriculum and methods of teaching have changed. Questions have been raised on the relationship of scientist and engineer, interdisciplinary versus specialized curriculum, undergraduate versus graduate training, and the place of the smaller schools versus the large university-research complexes that have developed at some universities. Various aspects of the subject of engineering education for the mining industry were discussed at the meeting on Mining and Mineral Engineering Manpower at the Michigan College of Mining and Technology, November 18-19, 1963. Meanwhile, the trend toward interdisciplinary training gathers momentum as illustrated by the establishment of the School of Engineering Science at Johns Hopkins, the Schools of Engineering and Applied Science at Columbia, Princeton, and Yale, the Division of Engineering and Applied Physics at Harvard and, more recently, the School of Engineering Science at Florida State University which cuts across the conventional areas of civil, mechanical, electrical, and chemical engineering.

Jan 1, 1964

By Kevin Connor

During 1984, minerals exploited in Burundi included gold, kaolin, lime, and peat. Over 1,100 troy ounces of gold was extracted and traded during the year as a result of the lifting of the Government ban on gold mining in mid-1983 and the establishment of an artisan mining program and licensed trading counters. Almost 2,000 tons of kaolin was mined for the manufacture of insecticides. Lime production was for domestic fertilizer applications. Amoco International and the Government signed an accord late in the year for a petroleum exploration program covering 600,000 acres of Burundi&apos;s onshore Ruzizi Plain and part of northeastern Lake Tanganyika. Amoco was expected to begin the exploration program by mid-1985. Anticipated program costs could run as high as $200 million.2 The Finnish company Ekono Oy completed its peat industrial energy development studies for the Buyongwe peat deposits of northern Burundi by the end of the year. The project assessed the quantity and fuel quality of 13,000 hectares of peatland and was part of a larger study for developing the Musangati lateritic nickel deposits of Burundi, estimated at 3% of the world&apos;s reserves of nickel. The Buyongwe peat would fuel dryers and an electrical generating plant for supplying power to nickel ore processing facilities. Briquetted peat would also be used as a substitute for wood and charcoal, presently the main sources of rural energy in the country and rapidly depleting because of deforestation. The study also evaluated the most economical methods to harvest the peat bogs. The study was financed by the International Development Association (IDA), United Nations Development Program (UNDP), Finnish Aid-Finnida, and the Burundi Government.

Jan 1, 1986

Provide a means for continuous measurement and display of respirable dust concentrations in a mine so that when high dust levels occur, timely, corrective measures can be taken. Approach Develop a personal dust monitor that (1) is small and light enough to be worn by a miner, (2) has the capability to continuously measure the respirable fraction of coal dust, (3) will display the respirable dust concentration in mg/m3, and (4) can store the average respirable dust concentration and sampling time of several sampling shifts for later play-back. How It Works The personal dust monitor (PDM-1) uses light scattering and convection air currents to sample the respirable fraction of coal dust. Convective air currents cause dust laden air to pass through an open-celled sampling chamber (light sensing chamber). A near infrared light emitting diode (LED) located in the PDM-1 emits pulses of light. The pulsed light passes through a focusing lens and glass window into the sampling chamber. The light is then reflected, scattered, and refracted by the airborne dust particles. Light scattered within the angles of 450 to 900 (the angles within which the intensity of the scattered light is most closely related to respirable-size dust particles) passes through another window and is focused on a light detector. The light detector signal is amplified and presented as analog output voltage for conventional recording. This signal is also converted to a digital signal which the microprocessor uses with its crystal clock to calculate the 10-second average dust concentration, the shift average concentration, the time-weighted average concentration, and the elapsed sampling time. The microprocessor also stores dust concentrations of the seven most recent sampling periods, controls the operation of the LED and detector, and operates the liquid crystal display (LCD).

Jan 1, 1983

By Dennis R. Dolinar, Eric R. Bauer

Skin failures of roof and rib in underground coal mines continue to be a significant safety hazard for mineworkers. Skin failures do not usually involve failure of the support systems, but result from rock or coal spalling from between the support elements. For instance, in 1997 more than 800 miners were injured by roof and rib falls, of which 98% were the result of skin failures [Bauer et al. 1999]. Also, nearly 80% of the roof and rib failure injuries occurred at or near the working faces in development sections. The face area is a zone where the potential for skin failure accidents and injuries and for roof and rib failures is high because of mining activity, ground readjustment due to changing stress conditions, and the higher exposure of mine workers. In addition, failures occur where the roof and rib are unsupported. This paper reviews the roof and rib accident statistics resulting from skin failure, and highlights the incidences by type, numbers and percentage, in-mine location, supported and unsupported roof, and worker activity at the time of injury. Also discussed are the causes of roof and rib skin failures, current and improved support methods and materials for skin surface control, and machine design modifications for improved roof bolter operator protection. It also reviews the historical literature on skin failures and control methods.

Jan 10, 2000

By Maria I. De Rosa, Charles D. Litton

The U.S. Bureau of Mines conducted experiments for predicting materials&apos; ease of combustion (smoldering onset, smoldering, flaming, and decomposition rates) by means of submicrometer smoke particle characteristics for the development of a simple test method. The experiments were carried out in an approximately 20-L furnace, with a 10-L/min airflow through the furnace for a 14-min duration, at set furnace temperatures of 150°, 250°, and 1,000°C. The variables studied as a function of time were the onset time of smoke particles, time and duration of maximum smoke particle generation, average concentration of smoke particles, and particles&apos; average diameter, mass weight loss, and furnace temperatures. Results show that the onset time of smoke particles is predictive of materials&apos; ease of smoldering, and the time of maximum smoke particle generation and its duration, coupled with mass weight loss, are predictive of materials&apos; ease of smoldering and flaming (depending on the experimental temperatures), and decomposition rates.

Jan 1, 1992

By Seth C. Schaefer

The Bureau of Mines investigated thermodynamic properties of Mn304 (manganomanganic oxide) and Mn203 (manganese sesquioxide). The standard Gibbs energies of formation (?Gf°) of Mn304 and Mn203 from their lower oxides were determined with high-temperature galvanic cells using stabilized Zr02 (zirconia) as the electrolyte. Potential measurements were obtained for the cell Pt, MnO, Mn304//Zr0 2//02(g, 0.0112 atm), Pt, with the overall cell reaction 6Mn0(c) + 02(g, 0.0112 atm) = 2Mn304(c), where- 02 refers to indicated partial pressure of oxygen at the reference electrode. Similar measurements were obtained for the cell Pt, Mn304, Mn203//ZrO2//02(g, 0.0115 atm), Pt, with the overall cell reaction 4Mn304(c) + 02(g, 0.0115 atm) = 6Mn203(c). Equilibrium oxygen pressures for the Mn0-Mn304-02 and Mn304-Mn203-02 systems were measured and may be expressed for the respective systems as [23,400 109 P02 T + 11.91 (764.9 - 1,208.6 K) and log p02 = - 11,957 + 9.66 T (968.6 - 1,208.2 K),] where pressure (p02) is in atmospheres and temperature (T) is in kelvins. Standard thermodynamic properties of Mn304 and Mn203 were derived from these measurements and auxiliary thermodynamic data from the literature.

Jan 1, 1982

By Wilbur I. Duvall

The Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole whose boundary is subjected to applied shear loads over four separated arcs. The results for the applied shear loads can be superimposed on the results for applied radial loads, given in a previous publication, to obtain a complete two-dimensional approximation of the stresses and displacements induced in the rock by tunnel boring machines anchored in a circular tunnel by means of four props. Analysis of the various solutions shows that the tangential tensile stresses induced on the boundary of the circular tunnel by applied radial loads can be minimized in the roof and floor of the tunnel by the application of appropriate shear loads to each of the four props. Thus when planning tunnel boring operations, consideration should be given to the in situ stress field in the rock and the induced stresses in the rock resulting from the applied radial and shear loads produced by the props of the boring machine.

Jan 1, 1968

CESIUM metal production increased sharply in 1963. Domestic Production.--Cesium metal was produced by The Dow Chemical Co., Midland, Mich., MSA. Research Corp., Callery, Pa., and by Penn Rare Metals, Inc., Revere, Pa. American Potash & Chemical Corp., Trona, Calif., produced some combined cesium and rubidium. This company, Penn Rare Metals, Inc., and Rocky Mountain Research, Inc., Denver, Colo., produced various cesium compounds. Complete production data on cesium and rubidium and their compounds were not available for publication. Consumption and Uses.-Substantially more pollucite was consumed to produce cesium metal and compounds in 1963 than in 1962 but the overall consumption of pollucite continued to be small.

Jan 1, 1964

By Forrest T. Moyer

Injury experience in the mineral mining and processing industries during 1968 was slightly improved in the nonfatal-injury record but worse in the fatality record. The resulting frequency rate of all injuries was slightly better, whereas the injury-severity rate retrogressed appreciably from the figure for 1967. Overall operating activity, as measured by man-hours of worktime, was slightly higher in 1968. However, there were several major segments of the mineral industries in which activity was lower owing to reduced demand for mineral products and to several major work stoppages. These statistics comprise the injury and work experience of all personnel engaged in production, exploration, development, maintenance, repair, and force-account construction work, including supervisory and technical personnel, and working partners and owners at mineral-producing and mineral-processing establishments in the United States. Data concerning officeworkers are excluded except for the oil and gas industry for which such information is not separable. All injury rates and totals are calculated from data before rounding. The data for 1968 are preliminary except for the anthracite, coke, petroleum and natural gas, native asphalt, peat, and slag industries, which are final. The figures represent full coverage for all industries except oil and gas for which coverage is not complete, particularly with respect to small companies.

Jan 1, 1970

By Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface metal/nonmetal mining categories during 1990–2001 by state and six successive 2-year time periods. Injury risk rates are derived, and ignition source, methods of detection and suppression, and other variables are examined. Fires involving contractors are also included in the analysis. The data were derived from Mine Safety and Health Administration (MSHA)mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and an increased awareness aimed at preventing and reducing fire hazards. It will also form a basis for future fire research programs.

Jan 11, 2004