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By Benjamin W. Haynes

Materials from phosphate rock mining and processing were analyzed for fluorine and uranium content as part of the Bureau of Mines program to more effectively recover resources from mining and mineral processing reject materials. The analysis of both feed and waste materials generated in the beneficiation and acidulation of phosphate rock was performed to obtain information on the disposition and concentration of these elements in phosphate rock processing streams. Fluorine was determined by a distillation-titration method and by ion chromatography. Uranium was determined by the dibenzoylmethane (DBM) method, the reliability being confirmed by roundrobin analysis of samples within Bureau of Mines research centers. National Bureau of Standards (NBS) Standard Reference Material (SRM) 120b-Phosphate Rock was also analyzed for fluorine and uranium to verify procedures and results. Fluorine values ranged from 0.3 wt-pct in gypsum filter cake to 3.7 wt-pct in phosphate rock concentrate. Uranium ranged from less than 5 µg/g in gypsum filter cake to 200 µg/g in a dried clay slime.

Jan 1, 1981

By E. Chin

The mineral industry of Bangladesh was totally dominated by natural gas production and its downstream uses. A small amount of cement was produced, and clays were used locally for ceramics and construction materials. Nitrogenous fertilizer was produced from natural gas and a modest, scrap-based steel industry produced steel for local consumption. The country has been developing and using its abundant and inexpensive gas reserves as fast as practical. The population, however, was predominantly dependent on agriculture for its livelihood. The industrial sector accounted for 10% of the economy, and most of the industrial output was directly associated with agricultural products jute, tobacco, and textiles. Industrial expansion, even with the availability of gas, was severely constrained because of limited domestic demand, lack of skilled work force and management, poor infrastructure, and a low rate of domestic savings. To put greater emphasis on the industrial sector, the Government established a National Committee for Industrial Development in July. The Committee instituted policy reforms in the areas of trade and investment. One important step was to move from a positive import list to a negative list, thereby permitting imports of items not restricted or banned. The system for recovering and approving new domestic or foreign industrial investments was streamlined to expedite what had become a cumbersome, bureaucratic exercise. To encourage industrial development in areas away from the crowded urban centers, several economic incentives reportedly were adopted. These included a reduced tax rate on imported machinery, exemption of import license fees, a reasonable debt equity rate, and a 9-year income tax exemption period.2 In the trade sector, imports increased 12% in fiscal year (FY) 19843 mainly

Jan 1, 1987

By Sathit Tandanand

Massive roof overlying the working seam in longwall operations can cause hazards if it does not cave readily behind the face supports. The overhang thus formed can overload the supports and endanger personnel when it collapses suddenly as a large rock mass. This Bureau of Mines report proposes the use of a concentrated load, either strip or point loading, applied onto the roof with the help of the upward thrust of the face supports. An experiment was conducted in the laboratory to obtain information about break characteristics and the values of significant parameters of three sedimentary rocks. The results were used to determine the breaking load requirement for a strong roof possibly encountered in typical longwall operations. The results show that the roof slab of moderate thickness can be fractured within the load capacity of off-the-shelf powered supports.

Jan 1, 1979

By J. W. Walkiewicz

The Bureau of Mines investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of MM-Co, MM-Co-Cu, MM-Co-Cu-Mg, and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy consisting of arc-melting the metals, crushing and grinding the resultant alloys, alining and compacting the powder, and sintering the compacts. Magnetic values of MHc = 4.7 kOe, BHc = 4.07 kOe, Br = 6.81 kG, and (BH)max = 10.0 MGOe were obtained with a MM-Co alloy containing 36±0.5 wt-pct MM. By substituting copper and magnesium for part of the cobalt, the values for MHc and BHc were increased to 29.0 kOe and 5.89 kOe, respectively. This intrinsic coercivity value exceeded that of Sm-Co alloy obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of Br to 6.90 kG and (BH)max to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum values of MHc.

Jan 1, 1981

By W. W. Weller

Heat-capacity measurements of sodium dimolybdate (Na2Mo207) and sodium ditungstate (Na2W207) were conducted over the temperature range from 51° to 298° K. The entropies of the two compounds at 298.15° K were calculated from the heat-capacity values and were used, in conjunction with other entropy data, to evaluate the entropies of formation of the compounds from their constituent elements and oxides.

Jan 1, 1963

By Carla A. Kertis

Because coalbed discontinuities often pose serious economic and safety problems in underground coal mines, criteria were documented for the recognition and prediction of discontinuities in advance of mining. Pennsylvanian strata in Indiana and Armstrong Counties, PA, were deposited as part of fluvio-deltaic complexes with channel-phase sandstones as the predominant type of coalbed discontinuity. Coalbed isopach maps constructed for this study delineated numerous want areas (areas of no coal) with elongate to linear geometries. A comparison of coalbed isopach and corresponding sandstone isolith maps of the study area revealed many examples of a thick-sandstone, thin-subjacent-coalbed relationship. Nearly 60 pct of the want areas in the study area were found to lie subjacent to thick (> 20 ft [6 m]) sandstone accumulations. In addition to erosion of the coalbed, channels may contribute to coalbed splitting, coalbed thinning over paleotopographic highs, abnormal coalbed thick- nesses, and deterioration of coal quality. If these features are considered, then approximately 80 pct of all interruptions in the economic coalbeds in this area result from channel activity. By using the criteria developed in this study and described in this Bureau of Mines report, the occurrence of coalbed discontinuities may be predicted and anticipated in advance of mining.

Jan 1, 1985

By Doris M. Hyde

Belize remained relatively insulated from the social and political turmoil that affected some of its Central American neighbors. This stability encouraged new foreign investments that assisted the economy, especially in tourism and agriculture. The mineral sector remained limited to construction-oriented materials. Oil exploration efforts continued by the various concessionaires.

Jan 1, 1987

By T. O. Llewellyn

The Bureau of Mines conducted laboratory batch beneficiation tests on a waste granite sludge from New Hampshire to determine the feasibility of recovering a reusable silicon carbide product. The granite sludge responded to attrition scrubbing, desliming, and flotation in either alkaline or acid circuits using fatty acid as a collector. Recovery of over 80 percent of the contained silicon carbide at grades of up to 96 percent SiC was obtained.

Jan 1, 1975

By Michael D. Fenton

The very modest-sized mineral industry of Afghanistan was burdened for another year with problems of internal strife occassioned by the presence of Soviet armed forces. Despite this, production of the few traditional commodities continued, and the mineral industry moved to develop additional mines and plants for both traditional and new products with considerable technical and construction assistance from the U.S.S.R. Among the limited range of mineral commodities for which production was reported, there were no startling changes between 1984 and 1985. Production of both coal and natural gas advanced only slightly, despite substantially higher 5-year plan goals, and cement output was down marginally. Probably the most significant development in 1985 was the Possibility that mine and/or smelter production of copper was initiated during the year.

Jan 1, 1987

By I. D. Shah

Thermal decomposition of copper (II) sulfate (CUS04) and copper (II) oxy-sulfate (CuO?CUS04) are important steps in the overall oxidative roasting of covellite (CuS) and chalcocite (Cu2S). Nonisothermal thermogravimetric techniques were used to investigate the decomposition reactions in flowing Na and air. Thermal decomposition of CUS04 and CuO?CUS04 followed "linear" kinetics with an apparent activation energy of 55±2 and 66±3 kcal per mole decomposed, respectively. These apparent activation energies comply with those previously reported when isothermal kinetic techniques were used. The addition of oxygen decreased the rate of decomposition, while small amounts of iron which were admixed with CuO?CUS04 did not have a significant effect. Neither oxygen nor iron had any appreciable effect on the apparent activation energy of the decomposition reaction.

Jan 1, 1972

By Suresh K. Bhatt, Dennis R. Dolinar

The roof bolt system of a mine, if properly selected and installed, can allow for better roof control and reduce the potential for roof falls. Because of this potential to reduce roof falls and improve ground control conditions, the National Institute for Occupational Safety and Health (NIOSH) has an interest in the types of roof bolts that are used by the coal industry. Further, NIOSH has conducted research into how various support parameters can affect the number of roof falls that occur, including support type. Today, the five main types of roof bolts installed in U.S. coal mines are mechanical anchor bolts, point-anchor or resin-assisted mechanical anchor bolts, torque-tension bolts, combination bolts, and fully grouted resin rebar. This paper describes each support in detail. Because of the importance of resin in the functioning of the majority of bolts installed, resin grouts are also discussed. Further, trends in the types of roof bolts used are reviewed. Over the last 10 years, the significant trend has been the large reduction in the relative number of mechanical anchor bolts that are installed. These bolts have been replaced mainly by the resin-grouted rebar system. Data are also presented to show the impact of these changes in bolting on the number of roof falls.

Jan 10, 2000

By John C. Holtz

The Bureau of Mines studied air contamination caused by diesel exhaust in a 10,000-ft ventilated tunnel. Sequential air samples were taken at the ends and middle of the tunnel during an operating cycle. Observed and calculated results for carbon dioxide, carbon monoxide, and nitrogen oxides were essentially in agreement. Nitrogen dioxide was present only in trace amounts. It was found that contamination was related to the volume of ventilating air, the number of haulage trips, train speed, and engine load.

Jan 1, 1968

By I. A. Jacobson

In a closely controlled laboratory retorting system for oil shale, a relationship was developed by the Bureau of Mines between the temperature in the retort and the weight ratio of ethylene to ethane in the gases produced. Reciprocal temperature was shown to be directly proportional to the log ([ethylene]/[ethane]). From this relationship a number, called retorting index, was developed. The retorting index has the dimension of temperature, but its magnitude depends on both temperature and residence time for the reactants in the heated zone in the oil-shale retort. The slopes of the lines relating reciprocal temperature and the logarithm of the ethylene-ethane ratios are nearly constant for each of the retorting processes for which data have been presented. The retorting index should be a valuable tool to control the operation of oil-shale retorts, either aboveground or in situ. If an optimum operating condition can be established, the maintenance of the optimum or the departure from it should be easily monitored by use of the index.

Jan 1, 1974

By Richard E. Dawes

Physical variables, a principal factor in the economies of mineral production, affect both capital and direct operating costs. By using a revenue-cost system for the framework, the analyses of revenue and cost categories demonstrate the relative importance of groups of physical variables, whether explicitly defined or not, to a lead-zinc mining operation. Physical variables affecting the producer represent about 60 percent of the total system influence as expressed by cost ranking. Other physical variables affect the remaining costs as controlled by the smelter, the transporter, and the landowner. Such resource conservation aspects as mineral losses due to mining method and mineral processing constitute a portion of the total revenue effects of physical variables. The physical variable revenue-cost system presented in this report offers a framework for cost-benefit analysis of mineral related research.

Jan 1, 1969

By C. B. Manula, R. L. Sanford, R. A. Rivell

This report was prepared by The Pennsylvania State University under USBM Contract No. 60111808. The contract was initiated under the coal Mine Health and Safety Program. It was administered under the technical direction of DMSE, with M. G. R. Schottler acting as the technical project officer. Mr. J. A. Herickes was the contract administrator for the Bureau of Mines.

Jan 1, 1974

By M. L. Skow, Maurice Deul, M. G. Zabetakis

This Bureau of Mines report presents a brief summary of the explosion trends in United States coal mines for the past 160 years. These trends show that in spite of the overall improvements in mine safety, the number of fatalities from ignitions of methane has actually increased in recent years. Suggestions are made of procedures that can be utilized to reverse this trend.

Jan 1, 1972

By Mridul Gautam, Alex Bugarski

Size Distribution and Deposition in Human Respiratory Tract: Particle Mass and Number Aleksandar Bugarski and Mridul Gautam National Research Center for Alternative Transportation Fuels, Engines and Emissions Department of Mechanical and Aerospace Engineering West Virginia University TOXICITY OF ULTRAFINES (MAUDERLY et al.) ? FINER PARTICLES PENETRATE MORE READILY INTO CELLS AND TIXROUGH TISSUE BARRIERS ? FINER PARTICLES HAVE GREATER SURFACE AREA PER UNIT MASS, AND A LARGE NUMBER OF TOXIC REACTIONS OCCUR AT THE SURFACE ? FINER PARTICLES DISSOLVE MORE READILY THAN LARGER PARTICLES THUS ENHANCING THE BIO- AVAILABILITY OF SOLUBILIZED COMPOUNDS EPIDEMIOLOGICAL STUDIES INDICATE THAT THE IMPORTANCE OF ULTRAFINES REMAINS SPECULATIVE

By Charles L. Kimbell

Tables 16 through 19 continue the series of providing the world merchant fleet distribution by type of vessel and the ranking of the major fleets by country of registry. Table 20 this year provides a summary of the world's liquid gas carrier fleet. These vessels are included in the totals given for the world's tanker fleet, but gives a breakdown demonstrating the growth of the importance of natural gas in the world's energy commodity consumption. Panama and Suez Canals Tables 21 and 22 provide the latest available information on the transit of mineral commodities through the Panama Canal, by number of vessels, direction, and the commodities transported. Although the number of vessels transiting the Panama Canal dropped slightly (0.5%) between 1989 and 1990, the total amount of cargo moved rose by 3.6% and the amount of mineral commodities moved rose by 7.2%.

Jan 1, 1993

By Martin H. Stanczyk

Ultrafine grinding of the industrial minerals mica, pyrophyllite, talc, marble, barite, and fluorite was accomplished using the Bureau-developed and patented attrition-grinding process. The materials, representing minerals of diverse physical characteristics, were batch ground in a 10-inch-diameter machine using statistically designed experimental test programs. The tests were made to determine large effects of variables such as feed pulp density, grinding medium size, and quantity of the electrical energy consumed during grinding on product particle size and bulk density. In designing the test programs, it was assumed that there was no interaction between the variables. Relatively coarse commercial flotation concentrates of mica, barite, and fluorspar and mine-run products of pyrophyllite, talc, and marble were readily ground into subsieve size ranges. Considering the great amount of particle size reduction obtained, the electrical energy requirements for grinding were very low. In general, the test results indicated that the best conditions for particle size reduction were approached when grinding with the coarser fraction of sand grinding media, the higher-sand-to-mineral weight ratio, and the higher feed pulp density.

Jan 1, 1972

By James P. Ulery, Stephen J. Kravits, William P. Diamond

This report presents results of a cooperative research project between the U.S. Bureau of Mines and Beth Energy Mines, Inc. Four coreholes (two before mining and two after mining) were drilled at a longwall mine operating in the Lower Kittanning Coalbed to obtain coal and rock samples from overlying strata to determine their gas content at various times in the mining cycle. The results of those tests indicate that 91 pct of the gas removed from the overlying strata came from coalbeds. Material balance calculations were made to compare the volume of gas produced both from gob gas vent holes drilled on the panel and gas removed by the mine's ventilation system with the volume of gas removed from strata directly overlying the panel to a height of 275 ft. This analysis indicates that only 40 pct of the total gas produced from the panel actually came from the strata directly overlying the panel. The remaining volume of gas production probably migrated to the Iongwall gob from overlying, and perhaps underlying, strata immediately adjacent to the panel and perhaps from greater distances downdip because of the establishment of a long-term pressure gradient in the study area.

Jan 1, 1992