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By Sean Gallagher

The restricted workspace present in low-seam coal mines forces workers to adopt awkward working postures (kneeling and stooping), which place high physical demands on the knee and lower back. Method: This article provides an analysis of injury claims for eight mining companies operating low-seam coal mines during calendar years 1996-2008. All cost data were normalized using data on the cost of medical care (MPI) as provided by the U.S. Bureau of Labor Statistics. Results: Results of the analysis indicate that the knee was the body part that led in terms of claim cost ($4.2 million), followed by injuries to the lower back ($2.7 million). While the average cost per injury for these body parts was $13,100 and $14,400, respectively (close to the average cost of an injury overall), the high frequency of these injuries resulted in their pre¬eminence in terms of cost. Analysis of data from individual mining companies suggest that knee and lower back injuries were a consistent problem across companies, as these injuries were each among the top five most costly part of body for seven out of eight companies studied. Application/Impact: Results of this investigation suggest that efforts to reduce the frequency of knee and low back injuries in low-seam mines have the potential to create substantial cost savings.

Jan 1, 2009

By R. R. Sayers, W. J. McConnell

"The health, comfort, and efficiency of men engaged in the mining industry may be impaired, in some instances very seriously, by abnormal physical conditions of the mine air or by variations in its composition. This is true in some of sheet metal mines of the West where high temperatures with varying humidities are encountered. Physiological studies have been made in some of these mines showing the effects of various temperatures end humidities. As it is difficult to carry out studies on many controlled temperatures, it was thought best to make the experiments in a laboratory and apply the results to the industry insofar as practicableThe effects of moderately high temperatures and humidities are more difficult to measure perhaps than the extreme conditions, but may be predisposing causes of fatigue, discomfort and disease, A cooperative study of the physioloical effects of heat and humidity is being conducted by the Bureau of Mines and the U. S. Public Health Service cooperative with the American Society of Heating and Ventilating Engineers, in the Research Laboratory of the Bureau of Mines at Pittsburgh, Pa."

Mar 1, 1924

By James A. Browning

Following an unsuccessful attempt earlier in the program to develop and market a drill channelling machine, we have designed and tested a new continuous channelling method which reduces operating sound levels to below 100 db. This new method relies on a small diameter oxygen-enriched burner to produce narrow channels. Sound intensities are reduced substantially compared to conventional channel widths. They are further reduced by a water spray directed immediately above the flame. Baffles placed along the top of the channel will reduce sound levels to below 90 db. Cutting rates are greater than those of existing channelling burners with costs per unit of channel area substantially reduced for those cases where oxygen costs are reasonable.

Jan 1, 1981

By Arnold B. Hubbard

Automatic control instruments were utilized by the Bureau of Mines for routine assays of large numbers of oil shale samples and other bituminous materials. The standard Fischer assay method was automated by automatically controlling the heating cycles of a battery of 12 electric heaters with electronic controllers and programmers. The condensers were cooled with a modified automatically controlled refrigeration bath. The complete assembly consisted of 12 retort units, necessary control instruments, and the refrigeration bath. This equipment was capable of producing more consistent results than those previously obtained with the gas-heated retorts and of increasing the output of assays substantially with no increase in operating personnel.

Jan 1, 1965

By Ronald P. Hollenbeck

The value of mineral production in Alabama increased 1 percent above the record high set in 1965. Alabama ranked second among the States in the production of bauxite, third in the production of masonry cement, native asphalt, and scrap mica, sixth in the production of portland cement, ninth in the production of iron ore, and tenth in the production of lime. The mineral industry of Alabama was dominated by the mining and processing of coal and stone, the manufacturing of cement, and the production of crude petroleum. These industries accounted for 87 percent of the State's total value of mineral production, compared with 85 percent in 1965.

Jan 1, 1967

By P. S. Lewis

Shortage of natural gas is reviving interest in low-Btu fuel gas made by gasifying coal in fixed-bed producers. The Bureau of Mines gasified strongly caking Pittsburgh bed coal over test periods lasting four days in an experimental gas producer located at Morgantown, W. Va, Mechanical stirring throughout the fuel bed was effective for keeping the fuel moving and this stirring made the operation successful; hence, the gas producer was named the stirred-bed producer. Nuclear density gages were applied as control instruments to indicate coal flow and fuel level, and to record the frequency and location of void spaces in the bed, The gas, of nominal 140 to 165 Btu/scf calorific value, could be burned in a boiler for generating steam.

Jan 1, 1972

By Joseph A. Hrabik

The Bureau of Mines compared the feasibility of mining deep phosphate deposits by a borehole mining system with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 150 ft or greater; however, at 50- and 100-ft thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasiblity of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is employed to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1983

By Joseph A. DeCarlo

THE TOTAL VALUE of sales of coal-chemical materials in the 10-year period 1948-57 increased 34 percent or at an average annual rate of approximately 3.5 percent. According to the Chemical Industry Facts Book, third edition, 1957, published by Manufacturing Chemists' Association, Inc., the production of industrial chemicals since 1939 "has grown at au average rate of about 10 percent" a year (p. 7). The rapid growth of the chemical industry increased requirements of chemical raw materials at a faster pace than could be supplied by coal carboniza¬tion, and view sources of supply became necessary. The petroleum industry in the past decade increased tremendously the flow of chemical raw materials to the chemical industry through the processing of crude petroleum and natural gas. Whereas coal carbonization supplied most of the raw materials for manufacturing synthetic organic chemicals before World War 11, coke ovens supplied only about 40 percent of the total used in 1957. Although the proportion of chemical raw materials supplied to the chemical industry by coke-oven operators declined, this source of supply is large and important to our economy. In 1957, the value of coal-chemical materials sold, including surplus gas used by producing companies, totaled $358 million, compared with $267 million in 1948. Major factors that contributed to this gain were (1) increased production of all coal chemicals and (2) higher prices for tax and light-oil products. Gains in output of coal chemicals resulted principally from expansion in carbonizing capacity of coke plants owned and operated by the iron and steel industry, as yields of the basic coal¬-chemical materials (tar, ammonia, light oil, and gas) varied only slightly during the 10 years under review.

Jan 1, 1959

By James R. Boyle

The value of Alabama's nonfuel mineral production in 1982 was $299.4 million, a decrease of $14.4 million from that of 1981; the decrease continued a downward trend that started in 1980. Output of most nonfuel minerals declined; cement, crushed stone, lime, sand and gravel, and clays were the major commodities produced in the State. Despite the decrease in mineral output, Alabama led the Nation in the production of crushed marble; was second in bauxite; third in ferroalloys and oyster shell; fourth in bentonite and dimension marble; fifth in common clay. fire clay, and kaolin; and sixth in masonry cement and lime.

Jan 1, 1984

By W. J. Crawford, P. M. Gruzensky

"Several experiments have been carried out in efforts to evaluate qualitatively a variety of electrolytes for refining bismuth. Most extensive work was done with the basic tartrate, hydrochloric acid, and hydrofluosilicic acid electrolytes. Deposits that are smooth and adherent can be obtained from these three electrolytes if low cathode current densities are employed. All three electrolytes were effective in purifying crude bismuth considerably, with additional purification indicated in each instance by a reelectrolysis step.With the basic tartrate electrolyte best results were obtained when the electrolyte was at 40° C. and contained at least 100 grams of bismuth per liter. An apparent disadvantage was depletion of bismuth from this electrolyte, causing the deposits to become spongy and nonadherent.The hydrochloric acid electrolyte had the greatest tendency to yield rough, dendritic deposits. Best deposits were obtained at cathode-current densities below 2 amperes per square decimeter. A small amount of glycerin helped to produce a smoother deposit, and adding sulfuric acid or methyl sulfuric acid retarded the deposition of impurities. Very good results were obtained in electrowinning bismuth from a bismuth trichloride-hydrochloric acid electrolyte.Smooth and adherent deposits were obtained from a hydrofluosilicic acid electrolyte, with very good refining as regards lead and silver impurities; however, higher reagent costs and slow decomposition of the electrolyte have discouraged its use.INTRODUCTIONMethods of recovering bismuth from ores and byproducts were underdeveloped for many years because of the limited uses for bismuth, the pharmaceutical industry being the chief consumer. In the past decade or so additional uses for bismuth, particularly in the metallurgical field, have brought about increased demand for the metal with the result that bismuth is being recovered from byproducts that were once discarded. In addition to such uses as low-melting alloys, solders, bearings, die setting, etc., some interest has been indicated in bismuth as a possible coolant for nuclear reactors. The advent of ductile bismuth and bismuth-alloy thermocouple wire has contributed greatly to temperature measurement, particularly in the below-zero range."

Jan 1, 1956

By M. S. Oudenhoven

The Bureau of Mines conducted an investigation to determine the theoretical stress distribution in the vicinity of explosively expanded rock bolt anchors independent of their bolts. Plane-strain solutions applicable to this problem were obtained by combining the field pressure with the uniform pressure that would be produced by vertically placed anchors having 2-, 3-, and 4-foot spacings. High rock stress which would be produced by an anchor was localized, as would be expected from St. Venant's effect, and increased as the field pressure decreased.

Jan 1, 1967

The Waukon iron deposit comprises about 210 acres situated 2-1/2 miles north of Waukon, in Allamakee County, northeastern Iowa. The deposits have been exploited intermittently since 1899 and have produced about 67,000 tons of concentrated iron ore. From January to May 1943, the Bureau of Mines investigated the deposit to determine the extent of the ore-bearing material and its amenability to concentration, Seventy-one test pits were sunk. Those that indicated are of a grade high enough to warrant concentration tests were sampled. Average grade of ore was indicated to be 37.02 percent iron and 27.78 percent silica on a dry basis. Beneficiation tests indicated that the percentage of recovery might be relatively low.

Jan 1, 1949

By C. M. McKinney

This report contains Bureau of Mines routine crude-oil analyses of 20 samples from5 areas on the arctic slope of Alaska. Two samples were condensates from the South Barrow gasfield, Barrow Lakes area. The remaining 18 samples were crude oils from the following areas: Barrow Lakes, 1 seepage sample; Umiat, 10 well samples; Cape Simpson, 1 seepage sample and 3 well samples; Fish Creek, 2 well samples; and Wolf Creek, I well sample. Table 1 summarizes information on the origin of the crude-oil samples, and table 2 summarizes characteristics of the samples. Item numbers in both tables correspond to item numbers of the analyses at the end of this report, and the samples are referred to by these numbers throughout the text.

Jan 1, 1959

By James E. Bell, Clyde B. White

"INTRODUCTION The Friedensville district was one of the most important zinc-producing areas in the United States from 1859 to 1893. The ore minerals near the surface were principally calamine and smithsonite, but with depth sphalerite was found in increasing proportions. The ore bodies of the district are reported to have been in chimneys, occurring in folded and faulted beds of Beekmantown limestone of Ordovician age.The Correll was one of five mines near Friedensyille that were exten¬sively exploited. The high-grade ore shoots were mined to a depth of several hundred feet, but it is believed that inability to compete with lower-cost production elsewhere, rather than exhaustion of the ore bodies, compelled the mines to close.There is no record to indicate that any attempt was made during the period of operation to explore for additional ore in the limestone beds down the dip below the mine workings. The possibility that exploration might reveal additional ore in the limestone beds below the known ore shoots led the Bureau of Mines to diamond-drill the Correll property between September 1943 and January 1944."

Jan 1, 1948

By Charles D. Litton

This U.S. Bureau of Mines report details the results of a series of large-scale experiments where small coal fires were used to ignite the conveyor belt at air velocities ranging from 0.76 to 6.1 m/s. In the tests, electrical strip heaters imbedded within a pile of coal were used to heat the coal to a point of flaming ignition. The flaming coal subsequently ignited the conveyor belt located approximately 5 to 10 cm above the coal pile. During the tests, temperature, CO, and smoke levels were continuously measured in order to determine both alarm time and level as the fire intensity progressed through the stages of smoldering coal, flaming coal, and flaming coal plus flaming belt. Analysis of the data leads to certain conditions of air velocity and sensor alarm levels that are required for early detection of conveyor belt entry fires. Two nomographs are presented, which define sensor alarm levels and sensor spacings as a function of belt entry cross-sectional area and belt entry air velocity.

Jan 1, 2010

By Allen D. Look

Uninterrupted shaft operations are an important economic factor in mine operation, and good shaft support is an important aid in preventing accidents and interruptions. More permanent supports can cut the hazards, costs, and delay incident to replacement of conventional timbers, especially where subject to decay. Installation of prestressed, precast concrete shaft supports in 100 feet of shaft at the Banner mine, Lordsburg, N. Mex., nave a satisfactory permanent installation in a section of shaft that had given trouble with conventional timbering. Use of rock bolts supporting gunited wire netting around the rock walls of the shaft prevented sloughing. No attempt was made in this paper to arrive at comparative costs of installation of various types of support. However, it was indicated that use of a lighter weight aggregate would be desirable in further use if prestressed precast members as placed in the Banner mine.

Jan 1, 1957

By Mark Flower

A 20L ignition test chamber has been used to test suspensions of 7 UK and world traded coals in air and O2/CO2 mixtures typical of oxy-combustion conditions. The coals varied in rank from sub-bituminous to bituminous and were tested in varying concentrations from the ignition limit to 400g/m3. Following each successful test the combustion residue was collected, weighed and analysed within a thermogravimetric analyser, allowing Q factors to be estimated. The ignition limit varied slightly in air, but was mostly around the 200g/m3 level. With the exception of Coal C, which was much harder to ignite, it correlated roughly with coal rank. The ignition limit changed significantly with O2 concentration when in mixed O2/CO2 gases. Only a few high volatile coals ignited in 21% O2/CO2 v/v, and then only with a 2500 J, rather than a 1000J, igniter. An increase in O2/CO2 levels to 30 or 35% gave ignition patterns similar to those carried out in air with a further increase to 40% having little additional effect. In addition the minimum ignition concentration decreased with increase in O2. Heterogeneous combustion or gasification of the coal by CO2 appears to be confirmed by comparing weight loss results for air and O2/CO2 mixtures respectively for an equivalent peak pressure rise.

Jan 1, 2009

By Lloyd Williams

A vertical air shaft in the Birmingham, Ala., iron district was sunk with a circular cross section and lined with concrete at a relatively low cost to provide needed ventilation for an iron-ore mine. The method of sinking the shaft is described, and the costs are stated in mar-hours with a descriptive list of equipment and a statement on the size and use of temporary buildings. Preparation began May 2, 1955, and the shaft was completed at a depth of [680] feet by September 22, 1956. By October 1956, all temporary building and [aft]-sinking equipment had been removed. The total direct-labor cost for the operation, including preparation and dismantling, was 50,700 man-hours, or 30.2 man-hours per foot. Total rock and dirt removed amounted to 17,523 cubic yards (in place), and the shaft lining required 4,635 cubic yards of concrete to form a circular air shaft with an inside diameter of 16 feet.

Jan 1, 1960

By B. J. Moore

This publication contains analyses and related source data for 252 natural gas samples from wells and pipelines in 17 States. All of the samples were obtained and analyzed during calendar year 1976 as a part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4862 and 576.3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the public in general. Eighteen previous publications have presented the results of 11,065 gas analyses prior to 1976. The first 3, Bulletins 486,4 576,5 and 617,6 contain analyses and related source data on 5,218 gas samples collected from 1917 through 1960. The other 15

Jan 1, 1977

By John R. Bartels

In laboratory testing, the Bureau of Mines established criteria by which common resin-grouted roof bolting systems can be evaluated and compared. Ultimate strength and stiffness were determined for nonten-sioned full-column, point-anchor, tensioned full-column, and debondable resin-grouted bolts, and for variations on full-column boltsn Bolt per-formances were compared using the performance of the 3/4-in full-column resin-grouted bolt as the standard. New and innovative systems can also be qualitatively compared against this standard. Since the medium into which a resin-grouted bolt is installed is one of the most important parameters affecting bolt performance, various host mediums were used in the testing: sandstone, concrete, simulated coal, simulated shale, and plaster. Bolt performances expected in other mediums can be inferred from the response patterns obtained in these mediums. Results indicate several functional differences among bolt types. Where resistance to shear is important, point-anchor bolts may outperform nontensioned full-column bolts at a lower cost. In medium-to soft-strength rock, tensioned full-column bolts perform best. Also, varying the resin-steel ratio seems to have little effect on the properties of a full-column bolt, when proper resin mixing is ensured.

Jan 1, 1985