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By W. W. Adams, T. D. Lawrence

"Despite the manpower shortage and other difficulties of operation in war time, the National Safety Competition of 1943 for the promotion of safety in the mineral industries of the United States was notable for having a larger enrollment of mines and quarries than in any other year except 1941 and 1942 since the yearly safety contests were inaugurated in 1925. The competition was also notable for having a larger number of man-hours represented by the competing companies than in any previous contest except that of 1942. The ratio of accidents and days of disability resulting from accidents to the number of man-hours of work performed was more favorable than in 1942; the accident-frequency rate was lower and therefore better than in 13 of the 19 years during which the annual safety competitions have been conducted, and the accident-severity rate was better than in 16 of the 19 years.The National Safety Competition is a yearly safety contest conducted by the Bureau of Mines, United States Department of the Interior. Companies that win first place in their respective group in the contest are awarded a bronze trophy, ""The Sentinels of Safety,"" which is provided by THE EXPLOSIVES ENGINEER magazine. Competing companies are segregated into six groups: Underground bituminous-coal mines, underground anthracite mines (in Pennsylvania), underground metal mines, underground nonmetallic-mineral mines, open-cut mines (without regard to kind of mineral produced), and open quarries (without regard to kind of stone produced). The bronze trophies are retained by the six winning companies for 1 year and are then transferred to the winners of the succeeding year's contest. On the pedestal of each trophy is engraved the names of the winners of the trophy. With the award of the trophies for 1943, therefore, the pedestal of each trophy bears the names of 19 winners."

Aug 1, 1944

By R. H. Nafziger

The Bureau of Mines evaluated 18 domestic titaniferous materials with widely varying compositions, mineralogy, and physical properties in electric-arc furnaces, Techniques were devised to recover both the titanium and iron values contained in these materials so that the reliance of the United States on foreign sources of higher grade ilmenites and rutile might be decreased. Most of the tested titaniferous materials responded well to lower grade or byproduct reductants, such as bituminous coals, charcoal, and coke breeze. Sufficient slag fluidity was realized by maintaining from 8 to 12 wt-pct iron in the slags; no contaminating fluidizers were required. Fluid slags containing up to 79, 70, and 54 wt-pct Ti02 were realized from east coast ilmenites, a rock ilmenite, and a titaniferous magnetite ore, respectively. A carbon-lined furnace shell is recommended for minimum slag contamination. Good results also were obtained during extended submerged-arc furnace tests.

Jan 1, 1980

By H. F. Yancey

The Baum-type jig used so widely to clean bituminous coals has not been adopted for anthracite. If proved suitable for anthracite, its use might lower preparation costs in some plants. Cleaning trials on a Pennsylvania anthracite in a laboratory-size Baum-type jig were undertaken by the Bureau of Mines to provide indicative information that would be helpful in determining whether the cost of a full-scale installation would be justified. Clean coal surpassing standard anthracite specifications was obtained in all sizes from Stove through No. 5 Buckwheat. Recovery effi¬ciencies were acceptable down to 3/16-inch size, but there was excessive loss of coal in the finer sizes. Thus the fine refuse produced in a commercial plant might re¬quire retreatment. A comparative cleaning trial in a dense-medium pilot plant provided a recovery efficiency only l percent higher than obtained in jigging.

Jan 1, 1957

By A. W. Deurbrouck

The Bureau of Mines reviewed available data on the effect of crushing high-sulfur coals for the liberation of impurities in the light of increasingly stringent air pollution regulations. The survey, which provided information on Appalachian region coals only, indicated that such important coal- beds as the Upper and Lower Freeport and the Upper Kittanning show significant sulfur reductions when crushed to 14-mesh top size. For many other coalbeds amenability to sulfur liberation by crushing was indicated, although too few samples were available to draw firm conclusions,

Jan 1, 1966

By A. W. Deurbrouck

The Bureau of Mines reviewed available data on the effect of crushing high-sulfur coals for the liberation of impurities in the light of increasingly stringent air pollution regulations. The survey, which provided information on Appalachian region coals only, indicated that such important coal-beds as the Upper and Lower Freeport and the Upper Kittanning show significant sulfur reductions when crushed to 14-mesh top size. For many other coalbeds amenability to sulfur liberation by crushing was indicated, although too few samples were available to draw firm conclusions,

Jan 1, 1966

By J. D. Davis

THE carbonizing properties of one medium- and and five low-volatile coals from West Virginia and one high-volatile A and two medium-volatile coals from Pennsylvania were determined by 800° and 900° C. BM-AGA carbonization tests and expansion tests in the sole-heated oven. Plastic properties of the coals and the yields and quality of their cokes and other carbonization products were determined. The low-volatile coals comprised a mine and a coke-plant sample of Pocahontas No. 6-bed coal from the. Black Eagle No. 1 mine, Wyoming County, W. Va.; a mine sample of Pocahontas No. 6 bed from the Louisville mine, Mercer County, W. Va. ; Davy Sewell bed was sampled at the Twin Branch mine, McDowell County, W. Va.; and Fire Creek bed was sampled at the Dunedin No. 1 mine, Raleigh County, W. Va. The medium-volatile coals were from the Fire Creek bed, Laurel Creek mine, Greenbrier County, W. Va.; Lower Kittanning bed, Springfield No. 4 mine, Cambria County, Pa.; and Upper Kittanning bed, Springfield No. 6 mine, Clearfield County, Pa. The high-volatile A coal represented the Upper and Lower Freeport beds, Kent Nos. 1 and 2 mines, Indiana County, Pa. In addition to the coals listed, high-volatile A coal from the Pittsburgh bed, Warden mine, Allegheny County, Pa., a standard blending coal, was used in blends in this investigation.

Jan 1, 1950

By Lung Cheng

The Bureau of Mines has installed passive water explosion barriers in two operating mines to determine their usefulness in U.S. coal mines. The primary objective of this field trial was to determine the effect of the explosion barriers on mining operations. Data were also obtained on the ability of the barriers to withstand the mine environment and on the effect of the barriers on belt operation, ventilation, worker travel, and rock dusting. Fifty barriers were installed at three separate beltway locations, and periodic inspections were made. A year after installation, no defects of the barriers or support hardware were detected, nor was any complaint as to the presence of the barriers made by the mine personnel. To date, 2-1/2 years after installation, the barriers have had no detrimental ef-fect on rock dusting, belt operation, or ventilation. Costs of material, fabrication, and installation are reported herein.

Jan 1, 1984

By Catherine C. Kilgore

The Bureau of Mines investigated the availability of manganese from known domestic occurrences. Eight of these deposits were found to have demonstrated resources totaling 420 million metric tons with an average grade of 10 percent contained manganese. They were found to be submarginally subeconomic. Economic evaluations of the eight deposits resulted in incentive prices ranging from $8 to almost $35 per long ton unit (22.4 pounds) of contained manganese. Comparing these prices with the current market value of $1.70 per long ton unit of manganese clearly illustrates the submarginal nature of the domestic ores analyzed. These domestic resources would probably not be developed except in the case of an extreme national emergency. Production from the eight deposits would take 3 to 6 years to develop, and the final product would be manganese ore concentrate, which could be used in the production of ferromanganese. If preproduction development began in 1981, annual production would peak in 1987 with 900,000 metric tons of recoverable manganese. Thereafter, production would see a steady decline unless additional resources were located or technologic improvements were made to allow processing of lower grade material, or unless mining and processing of ocean manganese nodules began to take place.

Jan 1, 1982

By Sarkis G. Ampian

Published optical microscopic and X- ray diffraction characteristics of the following compounds are critically evaluated and compared with Bureau of Mines data : Tricalcium aluminate , calcium monoa luminate , dodecacalcium heptaluminate , dicalcium silicate , tricalcium silicate , and sodium aluminate . A recommended set of definitive optical and X- ray diffraction characteristics is presented . These values are used to identify products of the lime soda sinter process for production of alumina . Polymorphism of gamma- , beta- , and alpha prime - dicalcium silicate is reexamined , and new data are presented on polymorphism of tricalcium silicate and sodium aluminate by high- temperature X- ray diffractometry . Polymorphism is not observed for tricalcium aluminate , calcium monoaluminate , and dodecacalcium heptaluminate . Bureau of Mines data indicating a stoichiometry of 12Ca0.7A10 for the phase 5Ca0.3A1 0₂ are discussed . A critical review of the literature concerning calcium dia luminate and sodium undecaluminate ( 8 -A10 ) is also included .

Jan 1, 1964

By K. K. Kelley

The entropy values at 298.1° K. for the elements and inorganic compounds, on which sufficient data were available for calculation in 1931, were discussed in a previous publication (96).3 Since that time the specific beats at low' temperatures of many more inorganic substances have been determined, and considerable advances have been made in the realms of spectroscopy applicable to the determination of thermodynamic properties. Moreover, a critical study of the existing vapor-pressure data made by the author (98) furnishes entropy of vaporization results suitable for obtaining approximate values of the entropies of a number of gases from the entropies of the solids or liquids. Consequently, it appears worth while at the present time to supplement the former publication, giving the new values now obtainable and making such revision in the older values as the data warrant. The methods of calculating entropies were discussed in previous publications (96, 98) and will not be repeated here. ENTROPIES AT 298.1° K. FOR INORGANIC SUBSTANCES In the following pages, the same arrangement is followed as in the previous publication (96). All entropy values are expressed in 15° gram-calories per degree Kelvin per gram-formula mass of substance. The figures given for gases do not include the effect of nuclear spin, as is nearly universally customary at present. The estimates of accuracy in the case of the values obtained from heat-capacity data apply only to the existing measurements and to the necessary extrapolations as they are made. It is assumed usually that the substances are in such an energy condition at the lowest temperatures reached in the specific-heat measurements that the usual normal type of extrapolation may be made. No allowance is made for error in this assumption. The recent work on Gd2SO4. 8H2O and FeC13 illustrates the difficulties that may arise in obtaining the entropies of some paramagnetic substances. Also the data and calculations for such substances as CO, H20, and N20 show that the correct entropy is not obtained in all cases by indiscriminate application of the usual

Jan 1, 1936

By J. M. Singer

This study was undertaken to obtain some fundamental information about hazardous mixtures of coal dust and methane (firedamp) likely to occur in mines. Fuel concentration limits for ignition of mixtures of coal dust, methane, and air have been determined by a hot-gas ignition method. The limiting concentration of each of the two fuels was usually less than that corresponding to its lean flammability limit in air. The lean limits of flammability of coal dust vary with the type and size of the dust; in this study coal dust concentrations were less than 80 mg/liter. Ignition jets were turbulent pulses (emerging from a channel of 0.5 cm diam) resulting from explosions of stoichiometric mixtures of methane, oxygen, and nitrogen, Temperatures of the ignition jets were varied by changing the oxygen index (OI) = O2/(02 + Nj2) of the primary methane-oxygen-nitrogen mixture (adiabatic flame temperatures from 2,000° to 3,000° K). The objectives of the study were to establish quantitative relations between concentrations of each fuel at ignition limits of hybrid mixtures and to study the mechanism of ignition of these hybrid mixtures by hot turbulent gases, Empirical equations were fitted to concentrations for four coals, namely) Pittsburgh Seam (sizes A, B, and C), Sewell No.2 Seam, pocahontas No.3 Seam, and anthracite. Equivalences of coal dust to methane were computed from these equations; equivalence being defined as -Ac/Am, where c is the coal dust concentration and m is the methane concentration, each in milligrams per liter of air. It was found that the equivalence increases as the temperature of the hot-gas jet decreases. In general, the equivalence is also an inverse function of volatile content of the coal and a direct function of the particle size, However, volatile con-tent in itself is not a sufficient correlating variable, nor is the specific surface area of the coal dust.

Jan 1, 1967

By L. L. Oden

The purpose of this research was to develop a method to remove copper and tin from the magnetic fraction of incinerated municipal refuse, as recovered by the Bureau of Mines pilot plant in College Park, Md. Copper, present in the scrap in a metallic form bonded to ferrous objects, was amenable to leaching in cupric ammonium carbonate solution. Copper levels in small 5-to 10-lb lots of treated scrap were reduced from the initial level, 0.5 to 0.6 pct, to 0.1 to 0.2 pct. Larger lots of scrap (100 lb) were treated less effectively because of poor contact of solution and scrap. Oxidation in the air or in aerated aqueous solution was applied to liberate tin from the dilute solid solution present on the surface of incinerated tinplate. Shredding of air-oxidized scrap or caustic leaching of scrap oxidized in solution reduced tin levels from the initial 0.25-pct level to about 0.1 pct.

Jan 1, 1973

The Florida phosphate industry, which supplies about three-quarters of the domestic phosphate fertilizer, produces tremendous volumes of phosphatic clay wastes (slimes). These clays retain a high percentage of water for extended periods of time. The clays also pose an environmental hazard because the disposal technique involves aboveground storage behind earthen dams. Although much research has been undertaken by numerous organizations to dewater slime, no completely satisfactory solution has been developed. In June 1972, a cooperative effort by the Federal Bureau of Mines and the Florida phosphate mining industry was initiated to develop a solution for dewatering the Florida phosphatic slimes. This report discusses various aspects of the slimes problem, reviews past research, makes recommendations for future research, and includes a bibliography of references and patents dealing with the subject.

Jan 1, 1975

By Thomas L. Vandergrift

To significantly increase the stability of underground excavations while exploiting the full advantages of confined rock strength, methods must be developed to actively control the distribution of stresses near the excavation. This U.S. Bureau of Mines study examines theoretical and practical aspects of rock pres¬surization, an active stress control concept that induces compressive stress in the wall rock through repeated hydraulic fracturing with a settable fluid. Numerical analyses performed by incorporating the rock pressurization concept into a variety of boundary-element models indicate that rock pressurization has the potential to improve underground excavation stability in three ways: (1) by relocating stress concentrations away from the weak opening surface to stronger, confined wall rock; (2) by inducing additional stresses in a biaxial stress field to reduce the difference between the principal stress components near the surface of the opening; and (3) by counteracting the tensile stresses induced in the rock around internally loaded openings. Practical aspects of the rock pressurization concept were investigated through a series of hydraulic fracturing experiments. The use of sulfur as a settable fluid for hydraulic fracturing was demonstrated, although problems related to sulfur viscosity suggest that other molten materials, such as wax, may be better suited to practical field application of the rock pressurization concept.

Jan 1, 2010

By T. Muldoon

Literature review and extensive field survey of line and check curtain materials and practices showed: ? Miners, in general, know how to set tight curtains, and do so when needed. ? The tradeoff is economic; tight ventilation is labor-intensive. Line and check curtain techniques found are catalogued and evaluated. A fieldworthy 10 ft extensible brattice to maintain a 10 ft setback was found in use in two mines on continuous miner faces. This technique was evaluated in the laboratory for leakage and methane control at the face. Significant results include: 1) Air leakage through a gap in the extensible curtain depends upon the ratio of the cross-sectional areas between entry and return as well as gap area; 2) Gap shape has no significant effect on methane concentrations at the face -increasing gap area diminishes ventilation effectivness; and 3) Substantial reductions of CH4 concentrations at the face were accomplished by brattice extensions with gaps of up to 5 ft2 in area. An "inby hook," inserted in the roof automatically to make possible the deployment of a longer (20 ft) brattice extension in the context of a remotely controlled miner, was tested in various roof types. Insertion of this design succeeded only in coal.

Jan 1, 1982

By Norman G. Foster

The mass spectra of 14 previously unreported alkylthiophenes are pre-sented. Low ionization voltage data of selected compounds from these 14 and 23 previously reported alkylthiophenes are presented and discussed for their value in supporting fragmentation mechanisms analytical correlations. A comparison with and corroboration of earlier correlations is made. Additional correlations concerning detection of side chain branching and the detection of ethyl-alkyl and propyl-alkylthiophenes are made. A discussion of the possible fragmentation routes and mechanism of fragmentation is given. Speculative structures are inferred s out some of the ions and hence this work provides a basis for suggesting fation mechanisms for the alkylthiophenes according to modern theories ass spectrometry. Verification of these mechanisms must await the availability of isotopically labeled molecules which are labeled in specific lotions that permit the definition of the paths of frag-mentation. Some suggestions for further work to generalize on the correlations and studies made to this point are presented.

Jan 1, 1965

By Henry M. Harris

A study was made by the Bureau of Mines to determine if shapes of oxide-glass compositions could be roll-formed at high temperatures, and to find the conditions required for adequate formability. A unit with directly connect' furnaces and heated rolls that allowed forming of most of the compositions developed. Glasses of the feldspar type were chemically unreactive with the alumina grains, and allowed the best roll forming. Optimum forming was attained at temperatures of 1,400° to 1,530° C, with compositions containing 30 or 40 percent feldspar and 60 or 70 percent alumina. Formability was better when compositions contained minus 325-mesh materials, rather than coarser or finer powders. In many cases, roll-formed shapes had physical properties equal to or better than the normally sintered shapes of the same composition.

Jan 1, 1967

By Wilbur I. Duvall, S. L. Windes, Leonard Obert

"Previous investigations, too numerous to be listed in entirety, have been performed to determine the physical properties of rock. When considered according to their objectives, most of these investigations can be grouped as follows: First, the geologic group (1,2),4/ in which the purpose was to obtain information on the physical properties of the rocks that make up the earth's crust. Particular emphasis has been placed on the determination of the elastic constants--that is, Young's modulus, the modules of rigidity, and Poisson's ratio – as these quantities determine the propagation characteristics of seismic waves. Second, the structural properties group (3 - 11), in which the physical properties of architectural or monumental stone, concrete and aggregate rock, road blocks (cobblestone), and the like were desired. The tests have been quite general and include, besides the elastic properties; the compressive and tensile strength, and the toughness, hardness, and weathering properties of many types of rocks.To .a lesser degree, investigations have been carried out to determine the physical properties of mine rock. A few reports (12 - 14) present data on the crushability and grindability of mine rock, and a large number of papers discuss grinding and crushing procedures and methods of analyzing the data (for example, see references 15 - 17). Some of the latter group also have given the results of tests on mine rock; however, comparatively few include an adequate petrographic description or information on other physical properties of the rock. A few papers,(18 - 22) have reported studies of the strength of rock specimens in respect to the strength of parts of mine structures, such as pillars, roof, arches, etc. Other papers (23 - 26) have discussed investigations on such subjects as primary and secondary crushing, diamond and pneumatic rock drilling, explosive breaking and shattering of rock, rate of drifting and miring, and other allied problems. The majority of these reports have given no more than a cursory, description of the rocks and have included no statement regarding the physical properties. When statements have been given regarding the physical properties, they have usually referred only to isolated tests, making correlations between variations in the physical properties and variations in the .test under consideration difficult, if not impossible. Some reports have included handbook values on such characteristics as the crushing strength, hardness, and toughness. This practice is not satisfactory, because these values are usually given for col¬lective types of rocks, such as granites, limestones, and marbles, and it is known that the variations of the physical properties within these groups is often larger than the differences between the groups."

Aug 1, 1946

By K. L. Paciorek

The primary objective of this final phase of Contract No. H0133004 was to provide a description of all experimental assemblies and procedures used throughout this project in such a detail as to permit duplication of the tests in any other laboratory. A further objective was to summarize and evaluate all results generated throughout the duration of this program and to tabulate all the materials and data in such a manner as to allow this report to be used as a reference index for specific compositions or groups of compositions regarding potential hazards arising from their use .in underground coal mining operations. The report also contains an updated survey of the literature on thermal oxidative degradation of compositions investigated under this contract.

Jan 1, 1978

By C. C. Stevenson, Thomas Varley, E. P. Barrett, ROBERT H. BRADFORD

The art of treating ores by the chloride volatilization process is still in the experimental stage. The process has not been sufficiently developed along metallurgical lines to warrant a definite statement as to the exact place it will occupy in the industry. The basic theory of the process has received the attention of prominent metallurgists for 20 years, and considerable research and experimental work have been carried on. Much of the experimental work done has never been published; if the accumulated results were made known, they would greatly aid,. the further development of the process. This bulletin aim~ to bring the salient features of the process to the attention of metallurgists for the purpose of furnishing information to and receiving comments from interested parties with the ultimate hope that the process will be a commercial success. If commercially utilized, the process will fill a long-felt want in metallurgy, especially in the treatment of oxidized and semioxidized or" carbonate" ores of copper, lead, and silver. Such ores are difficult to treat by gravity concentration or by flotation: in the former their tendency to slime upon crushing and their being of lower specific gravity than the sulphide minerals cause serious losses; in the latter much has been done in sulphidizing oxidized ores and subsequently recovering the artificial sulphides by flotation. Difficulties in proper sulphidizing and the low recoveries obtained have not balanced the cost of the treatment in many plants and in very few has it proved successful. Evidently there is a big void to fill in the treatment of these ores. No radical changes in present methods are forecast, but it is obvious that chloride volatilization can have a distinct place as a method of treatment for ores that are not readily amenable to present methods. In many plants it might replace concentration methods, especially where part of the mineral content in the ores exists in forms other than sulphides.

Jan 1, 1923