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By Peter F. Steidl

Seven degasification wells have been completed in the Pittsburgh coalbed at the new Emerald mine near Waynesburg, Pa. Funding was provided by the Bureau of Mines to perform stimulation treatments on five of the wells, to show that this is a feasible and economical means of degasifying part of a coalbed. The seven wells ranged in depth from 590 to 910 feet. Stimulation treatments used 25,260 to 42,660 gallons of foam and 7,400 to 12,800 pounds of 20/40-mesh prop sand. Pumping rates were 10.8 to 11.6 bbl/min and treating pressures were from 1,050 to 1,600 psig. On the day following stimulation, gas production ranged from a few hundred cubic feet per day to more than 100,000 cu ft/day.

Jan 1, 1978

By G. B. Gait

This report is the fifth in a series concerning the Bureau of Mines program for microfilming maps of abandoned mines in the Pennsylvania anthracite region. A catalog of the microfilmed maps of 47 of 49 major mines and 18 independent mines in the Southern field is presented. Previous reports included catalogs of microfilmed maps of mines in the Eastern Middle field, the Wyoming and Lackawanna Basins of the Northern field, and the Western Middle anthracite field.

Jan 1, 1978

By Gary W. Krantz

Fibered, portland-cement-based gunite products were applied in the Bureau of Mines Lake Lynn Laboratory Experimental Mine using a variety of pneumatic guns and gunning crews, The demonstrated wet-mix (with silica fume), dry-mix, and surface bonding products were sampled by the Bureau and subjected to a suite of engineering analyses. Gunite flexural and compressive strength, rebound, permeability, porosity, dust loading, shooting rate, crew requirements, and cost factors were evaluated. Steel, fiberglass, or polypropylene fibers were contained in all but two of the gunires tested. Both Bureau and private testing laboratory analyses are provided for some products. Electron probe micro-analysis and X-ray diffraction analysis were performed on the silica fume fraction of the wet-mix gunite to characterize the dust. Aggregate size fraction distribution analyses were performed to provide strength relationships. Results indicate that all of the commercially available fibered-gunite materials tested can provide beneficial sealant, spall prevention, or roof stability control attributes for underground mining environments when applied by an experienced crew using a well-maintained gun, in accordance with product manufacturers' recommendations and when used for the designated purpose.

Jan 1, 1984

By William L. Rice

Geochemical humus sampling techniques were used by the Bureau of Mines in investigating a potential large, low-grade gold deposit in the Orogrande district, Idaho. Conifer needle humus samples were processed by ashing and fire assay-atomic absorption analysis. An area bearing anomalous concentra¬tions of gold and silver was outlined by the geochemical method.

Jan 1, 1970

By Forrest T. Moyer

The safety record of the mineral and mineral-fuel mining and processing industries in 1965 was improved slightly, as indicated by the reduced injury-frequency and severity rates. The overall operating activity was higher in 1965 as measured by the gains in the number of men working and in the total man-hours of worktime. Injury Experience.-The rate of occurrence of all disabling work injuries in the mineral industries was 17.65 per million man-hours in 1965. This overall rate comprised frequencies of 0.28 for fatal and 17.37 for nonfatal work injuries, of which both were slightly better than the corresponding rates of 0.29 and 17.53 in 1964. Fatalities totaled 537; 5 less than in 1964. However, the total of 32,982 nonfatal injuries was 575 higher than in 1964. This larger number of nonfatal disabilities was offset by the increased worktime so that the nonfatal frequency rate decreased in 1965.

Jan 1, 1967

By W. W. Adams, V. E. Wrenn

"Production of explosives in the United States during the calendar year 1936, as represented by reports of sales by manufacturing companies, totaled 391,604,500 pounds, an increase of 27 percent over the amount produced during 1935. This quantity included 81,698,375 pounds of black blasting powder (granular and pellet), 262,047,106 pounds of high explosives other than permissibles, and 47,859,019 pounds of permissible 5/ explosives.The manufacturers' reports to the Bureau of Mines classify the sales of explosives according to five main classes of work in connection with which the explosives were used.Coal mines used 87 percent of the total amount of black blasting powder sold, bituminous-coal mines 79 percent, and anthracite mines 8 percent; coal mines also consumed 98 percent of all permissible explosives and 9 percent of the high explosives other than permissibles. The coal-mining industry consumed 16 percent more explosives in 1936 than in the preceding year, the increase at bituminous mines being 21 percent and that at anthracite mines 4 percent.Metal mines used 29 percent of the high explosives other than permissibles and less than 1 percent of the black blasting powder and permissible explosives. The total quantity of the three classes of explosives used in metal mining in 1936 was 36 percent more than the quantity so used in 1935."

Jul 1, 1937

By V. E. Erwin, W. W. Adams

"Production of explosives for industrial use in,the United States during 1934 continued the upward trend begun in 1933 from the low-level output of 1932, and the output in 1934 was only slightly less than in 1931.Reports to the United Stated Bureau of Mines from companies engaged in the manufacture of industrial explosives showed that the quantity of explosives manufactured in the United States and sold during 1934 for use within the various States was 314,767,922 pounds - 23 percent more than in 1931.Production during 1934 included 39,207,845 pounds of permissible explosives 5 206,625,027 pounds of high explosives other than permissibles, and,68,935,050 pounds of black blasting powder of which 37,192,700 pounds were in granular form and 31,742,350 pounds in pellet form. These figures represent an increase over 1933 of 15.6 percent for permissible explosives, 30.9 percent for other high explosive, and 7.4 percent for black powder.Coal-mining operations were the chief consumers of permissible explosives; 99 percent of the total output in 1934 was used, in coal mines. The proportion used by bituminous mines was 59 percent and by anthracite mines 40 percent. Coal mining was likewise the principal consumer of black blasting powder, taking 88 percent of the total sales during 1934; of this proportion, bituminous mines received 78 percent and anthracite mines between 9 and 10 percent. Consumers of high explosives other than permissibles were more varied; the reports showed that 11 percent of the total quantity sold was for coal mining, 22 percent for metal mining, 17 percent for quarrying and nonmetallic-mineral mining, 46 percent for railway and other construction work, and 4 percent for all other purposes."

Oct 1, 1935

By Richard J. Mainiero

The Bureau of Mines investigated coal-mine-type short-delay electric detonators marketed by three domestic manufacturers to determine the accuracy of delays and the probability of overlap between adjacent de- lay periods. The Winzer index was computed and compared with the probability of overlap. A close agreement between the Winzer criterion and overlap probability was demonstrated. A permissible blasting unit capable of delivering a maximum firing energy of 4.0 J and a digital oscilloscope were used to measure the delay time with an accuracy of 20.25 ms. Another oscilloscope and a pulse transformer were used to record firing current. Experimental data indicated negligible overlap probability in detonators of shorter delay periods: periods 1 to 4, which correspond to 25 to 250 ms. However, a significant probability of overlap was detected in some detonators of longer delay periods: periods 5 to 9, which cor- respond to 300 to 500 ms.

Jan 1, 1985

By R. C. Ellman

Significant effects of in-the-mill drying on the pulverization of lignite have been demonstrated in an experimental impact-type pulverizer by tests in which the primary variable was temperature of the sweeping gas. Reduced power requirements and increased product fineness were observed as the extent of drying was increased. Pulverization with in-the-mill drying was studied in comparative tests made on lignites from five mine sources. All of the lignites responded in a similar manner; however, differences in the pulverizing characteristics of the individual lignites were significant. For one lignite, the electrical input to the pulverizer driving motor with minimum sweeping-gas temperature was 33.9 kw.-hr. per ton, decreasing to 14.0 kw.-hr. per ton with a sweeping-gas temperature of 658° F.; for another lignite, at comparable operating conditions, the electrical input decreased from 59.1 to 19.0 kw.-hr. per ton. In the first case, the product fineness increased with increasing temperature of sweeping gas from 65.2 to 79.2 percent through a 200-mesh sieve, and in the second case, from b2.7 to 86.9 percent through a 200-mesh sieve.

Jan 1, 1962

By Robert L. Crosby

The Bureau of Mines investigated the substitution of cement copper powder for commercial copper powder in an Fe-7 pct Cu-l pct C powder metallurgy alloy. Copper powders from six different commercial cementation operations were separately upgraded by screening and hydrogen reduction. They were then mixed with commercial iron and graphite powders to form the Fe-7 pct Cu-l pct C alloy. Various chemical and physical properties were determined on the upgraded cement copper and the alloy powders. Mechanical, physical, and chemical properties were determined on green and sintered specimens made from the alloy powders. Mean tensile and bending strength of sintered specimens were significantly lower than the means from specimens made from commercial metal powders. The lower strengths are apparently related to poor sinterability.

Jan 1, 1970

By D. S. Colby, E. M. SEELEY

The total production capacity of the natural-gasoline industry increased to 27,212,000 gallons (647,905 barrels) daily on January 1, 1950, from 21,322,000 gallons (507,670 barrels) daily on January 1, 1948. The rate of growth during these 2 years averaged 13 percent per year, compared with 9 percent per year from 1946 to 1948 and 6 percent from 1944 to 1946. The total number of operable plants on January 1, 1950, was 554, 5 more than at the beginning of 1948. The number of absorption plants increased by 12, the number of cycling plants by 7, and the number of combination plants by 4. The number of compression plants and charcoal plants continued to decrease. Absorption plants accounted for 67 percent of the total capacity on January 1, 1950, compared with 62 percent 2 years previous. Eighty-two per- cent of the expansion in these 2 years was in absorption-plant capacity. Cycle plants accounted for 24 percent of the total industry capacity at the beginning of 1950, compared with 27 percent on January 1, 1948. The average daily capacity of absorption plants increased from 38,400 gallons at the beginning of 1948 to 50,600 gallons at the beginning of 1950. During the same period, the average daily capacity of cycle plants decreased from 150,200 gallons to 144,100 gallons. Texas showed the largest gain in number of plants 13 absorption, 4 compression, and 4 cycling plants. The State accounted for 67 percent of the gain in capacity and on January 1, 1950 had 50 percent total national capacity. Louisiana followed with 7 additional plants. Pennsylvania reported 14 and West Virginia reported 13 fewer plants than in 1948. Most of these reductions were in the number of compression plants.

Jul 1, 1950

By F. J. Smith, W. A. Gallagher, C. A. Herbert

"INTRODUCTION A fire started about 10 a.m., November 10, 1947, at the Kings mine, Princeton Mining Co., Princeton, Ind., about 1,800 feet inby the main shaft bottom on the main west haulage road at a point estimated to be 2 miles from the faces of the main west entries. No lives were lost, as 27 men escaped from the mine after a series of explosions, which necessitated sealing the mine on the surface. This information circular shows"" how adverse conditions might be overcome, when reopening a sealed mine, by expert planning and close cooperation on the part of various organizations. Conditions found in the mine after it was reopened were comparable to the worst that had been anticipated, yet the mine was recovered with comparatively little difficulty and a minimum of risk. The open workings in the mine covered a vast area, but most of the mine resumed production of coal after being sealed for only 37 days.The information contained herein also points to the desirability of adhering as closely as possible to a predetermined schedule of operations."

Feb 1, 1949

Table 1.-Employment and injury experience at metal mines in the United States, by industry groups [ ]

Jan 1, 1967

By Thomas M. Nasiatka

Tests with a high-pressure water jet were conducted in the steeply pitching Roslyn No. 5 bituminous coalbed in the Roslyn No. 9 mine, Roslyn, Wash., to determine the feasibility of extracting coal from pillars and from a solid coal face in development without drilling and blasting. During pillar mining, using a hand-held monitor, the best results were obtained with a 0.150-inch- diameter nozzle, a water pressure of 3,500 psi, and a flow rate of 38.5 gpm.3 The rate of mining and productivity were 0.74 ton per minute and 16.6 tons per man-shift, respectively. During development mining, using a monitor mounted on a roof jack, the best results were obtained with a 0.148-inch-diameter nozzle, a water pressure of 4,500 psi, and a flow rate of 40.0 gpm. In one section of the mine where the coal was relatively hard, the rate .of mining and productivity were 0.10 ton per minute and 5.7 tons per man-shift, respectively in another section of the mine where the coal was relatively soft, the rate of mining and productivity were 0.51 ton per minute and 8.3 tons per man-shift, respectively. The tests showed that hydraulic mining methods were more productive than conventional mining methods in pillar mining. In development the productivity of hydraulic mining depended primarily upon the coal hardness. Compared with conventional methods, hydraulic mining methods were less productive where the coal was relatively hard and equally as productive where the coal was relatively soft.

Jan 1, 1963

By Wilson Blake

The Bureau of Mines used a mathematical model based on the finite element method of stress analysis to calculate stresses and displacements surrounding an open pit mine in a gravity-loaded rock mass. Comparison of the finite element solution for a semicircular notch in a gravity-loaded plate with the theoretical solution for a semicircular notch in a plate under uniform compression parallel to the free boundary demonstrates the inapplicability of the latter method to openings at the free surface of a gravity-loaded medium. High stress concentrations are formed at irregularities along the boundary of an open pit in a gravity-loaded continuous competent rock; however, for this type of rock the magnitudes of the stresses are too low to be considered a major factor in open pit slope stability. High stress magnitudes will occur if, in addition to the gravity stress field, a large horizontal stress field exists.

Jan 1, 1967

By Gary E. Sherman

The Bureau of Mines estimated the remaining lode gold endowment of eight mining districts in Alaska using historic production data. A log-arithmic model of cumulative tonnage of ore processed versus cumulative grade was applied to the following districts: Chichagof, Fairbanks, Homer, Hope-Seward, Juneau, Ketchikan, Prince William Sound, and Willow Creek. To assess the remaining endowment, a computerized production data base was compiled from Bureau records. These data were aggregated in 5-yr intervals for each district. Data were sorted in order of declining grade, and log cumulative grade was plotted against log cumulative tonnage. Linear regression was performed on the data for each district. The linear equation for each curve was used to predict remaining endowment at a limiting mining grade. Based on conservative extrapolation of the grade-tonnage curves, a substantial total endowment of 8,415,100 tr oz of gold remains in the eight districts. The districts with the greatest remaining endowment are the Juneau, Chichagof, Fairbanks, and Willow Creek Districts.

Jan 1, 1987

By E. M. Kawenski, J. K. Richmond, M. J. Sapko, G. C. Price

This Bureau of Mines publication presents investigators' reports of all major coal mine explosion disasters that occurred in the United States from 1959 through November 1981, along with a brief analysis of common factors in these disasters, The report reviews the Federal mine health and safety acts of 1969 and 1977, and discusses how implementation of these acts has reduced the number of both fatalities and disasters, Current Bureau health and safety research is summarized, and an appendix lists most of the ignitions and explosions in the period of record,

Jan 1, 1983

A survey of roof and pillar conditions in underground limestone mines in the United States has revealed that bench mining of the floor between pillars can cause instability in the pillars at the perimeter of the benched area. Increased loading of these pillars was observed at several mines. Large inclined geological structures that are exposed in pillar ribs were observed to contribute to pillar instability. The paper describes a study that was carried out using numerical models to assess the effects of bench mining on pillar load and stability. It was found that the benched pillars shed load onto the surrounding pillars owing to their reduced stiffness. The pillars at the perimeter of the benching area will start shedding load as soon as benching increases the height of one side of the pillar. A case study is described which shows the effects of bench mining on limestone mine pillars.

Jan 1, 2007

By Manuel Gomez

Dehydrogenation factors, proximate analysis, and ultimate analysis were examined as predictors of the low-temperature -carbonization properties of coals varying in rank from lignite through anthracite. All factors studied contributed to reduction in variance of the sample populations investigated. Response surface regression models based on variables from proximate and ultimate analyses of coal were constructed for eight low-temperature carbonization assay product and gas component Fields. These models were tested with independent samples that included drill cores, sized fractions, petrographic fractions, and run-of-mine coal. The models developed were used to predict low-temperature carbonization yields or coals from major fields of Wyoming. This information was cast in the form of contour plots describing the potential low-temperature carbonization product yields of Wyoming coals and the properties of the resultant char or coke. The variables used as input v the models may be measured and collected during exploration; thus, the carbonization properties of a seam can be determined in advance of mining. The information presented in this report is useful in that it broadens the deciionmaking base for management when either mine locations or coal conversicl plant sites, or both, are being considered.

Jan 1, 1971

By Thomas G. Carnahan

The Bureau of Mines conducted research to simulate in situ leaching of a chalcopyrite ore. The purpose was to obtain a direct comparison between moderate-temperature and elevated-temperature in situ leaching of copper trom minus la-inch ore and to analyze the sulfuric acid and oxygen requirements of the leaching system. Experiments employing oxygen were conducted at 35° and 90° C on 362-and 367-1b ore charges, respectively, under flooded conditions and at 400 psig. At 90° C, 47 pct of the copper was extracted in 913 days of leaching; at 35° C, 27 pct of the copper was extracted in 915 days. Diffusion into and out of the ore fragments con-trolled the rate of leaching. Oxygen consumption was 1.46 lb/lb of copper extracted at 35° C and 3.15 lb/lb of copper extracted at 90° C. Sulfuric acid requirements of the ore were 5.49 and 7.48 lb/lb of copper extracted at 35° and 90° C, respectively.

Jan 1, 1982