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By Ann G. Kim

Samples of gas were obtained directly from the coalbed during drilling of horizontal and vertical boreholes in six different formations. The samples were analyzed by gas chromatography for C1 to C5 hydrocarbons and for O2, N2, H2, He, and Co2. Methane in the gas varied from 63 to 99 percent; carbon dioxide from 0.1 to 15 percent. The CH4/CO2 ratio varied and showed no apparent correlation with age, rank, or bed. The majority of samples contained ethane, propane, and butane; hydrogen and helium were found in some samples. Oxygen and nitrogen were usually present, possibly as a result of air contamination. A more extensive sampling program would be necessary to establish relationship between the amount and composition of the gas in the coalbed and other factors.

Jan 1, 1973

By Willard L. Hunter

The Bureau of Mines smelted samples of chromite ore and concentrate from the General Services Administration (GSA) purchasing depot at Grants Pass, Oreg., in a submerged-arc furnace to establish smelting conditions and the energy requirement to produce high-carbon ferrochromium. Raw material, in the form of ore, flux, and reductant, and electrical energy are available on the Pacific coast to smelt the chromite. The concentrate can be smelted without prior agglomeration by employing hogged wood (wood chips) as a major portion of the reductant. The energy requirement is relatively low, about 3,960 kw.-hr. per ton of alloy. The ferrochromium produced will contain about 60 percent chromium. In addition to the smelting data, a statistical summary of the grade and amount of chromite purchased during the stockpile program and estimated chromite reserves and production volume are given. It is estimated that 632,000 tons of Cr203 contained in chromite of all grades is available in the western coastal States. Of this total there appears to be sufficient metallurgical-grade and beneficiable ore to sustain a smelting operation for 25 years at a consuming rate of 25,000 tons a year, utilizing material comparable to that delivered to the Government stockpile.

Jan 1, 1961

By Anthony Iannacchione

One of the more pressing engineering problems for deep longwall mines in the Southern Appalachian Basin is to design longwall systems that will eliminate catastrophic coal pillar failure from the working environment. The purpose of this study is to quantify the behavior of a particular size abutment pillar prone to burst or bump. Because the 24.4-111 (80-ft) square abutment study pillar is within the pillar size commonly used in this region, understanding the behavior of this pillar should aid in future efforts to design optimum mining strategies. This research has attempted to construct the pillar stress and roof-to-floor convergence profiles in order to evaluate the ultimate strength, deformation modulus, visco-elastic deformation, and violent failure characteristics of the pillar during longwall mining. This information reflects the overriding influence of the local geologic characteristics on bursts, provides the field measurements needed to verify concurrent modeling studies, and suggest some basic mechanisms associated with the coal pillar bursts discussed in this paper.

By L. C. IlsLey

A specially recommended cable is a rubber-sheathed cable that has met the minimum performance requirements for cables as set forth in Schedule 20. The first in the series of recommended cables was listed September, 1930, by an ad- vance notice published as Information Circular 6375 which described the conditions under which the cable tests were made. Since that time six additional cables have met the test re- quirements and have been specially recommended. The complete list of specially recommended. cables is as follows: Specially recommended-cables Cable Symbol No. Hazacord No. 2 BM1 Stranding 19 x 7 Hazacord No. 3 BM2 do. Hazacord No. 4 BM3 do. Super-service No. 3 BM4 7 x 19 Super-service No. 2 Super-service No.. 4 BM5 do. BM6 do. Super-service No. 4 BM7 7x 7 Manufacturer Hazard Insulated Wire Works (division of the Okonite Co.) Do. Do. Rome Wire Company (division of the General Cable Corporation) Do. Do. Do. The cables listed were all twin (parallel duplex) cables having outer belts or cov- erings of approximately -inch high-grade rubber compound, and have the same general appear- ance and relative dimensions as the types of twin cables in general use. The cables were tested under conditions designed to show their approximate perform- ance under mine conditions. Only twin-type cables have met these test conditions. Although the recommended trailing cables are much better and safer for mine use than other cables and withstand being run over by a 7-ton car, they should not be considered as 100 per cent safe. The 7-ton car test represents the minimum limit requirement effective at present under Schedule 2-C, but the test car operates on a straight and level track, and thus does not represent the more severe conditions of mine use such as might result from uneven and curved tracks.

Mar 1, 1931

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

4. Preliminary Study - Remote Seal Checker 4.1 Introduction Determination of the completeness of each individual seal at the time of its emplacement is essential for an effective remote sealing system. A satisfactory seal checking technique should provide a signal which: (1) indicates percentage completion as the seal is emplaced (2) provides a definite indication of a complete seal (3) indicates the size of the unsealed area if a complete seal is not feasible This information is required to establish the need for additional seal material, the need for additional seals, and the risk likely involved in entering the mine., In many situations it is as important to know the quality of a seal as it is to build an effective one. It is likely that with repeated use the remote sealing technique developed by Foster-Miller Associates will be sufficiently reliable and predictable to preclude the seal checking requirement. It is recommended, however, that each seal be checked during construction to insure its completeness and increase the level of confidence so necessary in reopening the mine. 4.2 Description of General Problem Several characteristics of remote mine seals are important in considering techniques for evaluating the effectiveness of these seals. These include:

Jan 1, 1973

By Alex C. Smith, Thomas P. Mucho, John B. Walsh, Alden Ozment, Michael R. Thibou, Michael A. Trevits

The National Institute for Occupational Safety and Health (NIOSH), with US Foam Technologies, Inc. and On Site Gas Systems, Inc., conducted research on the remote application of extinguishing agents with the intent of improving deployment strategies to limit miner exposure and to help ensure the best possible outcome during a mine fire. Full-scale in-mine were conducted at the NIOSH Lake Lynn Experimental Mine to determine the flow characteristics, stability and fire-suppression capability of gas-enhanced foam. The in-mine experimental work was designed to evaluate movement of gas-enhanced foam through mine workings closely simulating an underground coal mine environment and how long gas-enhanced foam would remain stable. This paper presents results of the experiments and provides valuable insight into mine fire deployment strategies for gas-enhanced foam technology.

By Willard L. Hunter

The separation of tantalum and columbium by solvent extraction was under-taken as part of the Bureau of Mines research program to improve methods for extracting, separating, and reducing these elements to metal. The diethyl ketone aqueous HCl-HF system was one of several systems studied to determine the effect of metal and acid concentrations in aqueous solutions upon the transfer of tantalum and columbium into selected ketones. The tantalum-columbium oxide mixture used in this investigation was obtained by chemical extraction from Geomines slag. The investigation showed that tantalum 99.4 percent pure and columbium 97.2 percent pure can be produced by the selective transfer of tantalum into diethyl ketone from a solution of 2-N HF and 1-N HC1. The relatively low acid concentration necessary for tantalum transfer and the excellent selectivity of the system recommend its use for the separation of tantalum and columbium.

Jan 1, 1961

By M. MacLaughlin, J. Whyatt

A case study is presented that relates statistical descriptions of joint sets to the distribution of local wedge failures along the crest of a catch bench at the Yellowstone Talc Mine. The fracture sets and bench width were mapped by teams of geological engineering students from Montana Tech under the direction of Dr. Mary MacLaughlin. The students analyzed the fracture data, conducted physical property tests, and used a beta version of a NIOSH program “Bwedge” to predict the distribution of surviving bench widths. In the course of this analysis the students developed evidence of software performance issues that, unfortunately, frustrated their analysis. These have now been addressed and a full analysis completed. The analysis confirms the validity of the student mapping program and provides insight into the effects of blasting and excavation practices on the bench. It also provides a tool for exploring the pattern of bench crest failure that would result from variations in both bench geometry and blasting practices.

By L. E. Schultze

The Bureau of Mines operated a mineral recovery unit to recover metal values from post-flash geothermal brines from the Salton Sea known geothermal resource area as part of its research into the use of plentiful resources. The brine was available for metals recovery after its heat content had been used to generate electricity. The brine source was treated with lime to precipitate the contained iron, manganese, lead, and zinc before injection of the heat-depleted brine into the underground reservoir. Data are presented on the effects of process variables, such as rate and method of lime addition and air oxidation versus air exclusion. Variations in precipitation of metal values, composition of precipitates, effectiveness of slurry thickeners, and methods of treating the precipitates to recover metal values are discussed.

Jan 1, 1982

By F. P. Haver

A procedure is described for recovering both lead and sulfur from galena flotation concentrate, comprising the following steps: (1) Aqueous oxidation of the concentrate, using ferric sulfate to convert lead sulfide to sulfate and to give elemental sulfur; (2) regeneration of the ferric sulfate by electrolysis in a diaphragm cell; (3) treatment of the leach residue with ammonium carbonate solution to change the lead to an acid-soluble form and to produce ammonium sulfate as a byproduct; (4) solution of the lead carbonate in hydro-fluosilicic acid followed by electrolysis to recover the lead as metal and regenerate the acid; and (5) extraction of the elemental sulfur from the final residue with an organic solvent. About 90 percent of the lead can be recovered by the above method as 99.9-percent-pure metal, together with two-thirds of the sulfur--half in the elemental form and half as ammonium sulfate.

Jan 1, 1970

By S. J. Hussey

A jig tailing with gold content ranging from 0.33 to 0.43 oz/ton was leached in weak cyanide solution with extractions of up to 97 pct in 24 hours. By countercurrent batch leaching studies and laboratory pilot plant operation, minus 10- plus 20-mesh and minus 6- plus 16-mesh coconut carbon were loaded to 700 oz/ton of Au. Minor silver in the ore reported in the carbon in amounts of up to 100 oz/ton. Gold adsorption rate data and an equilibrium adsorption curve for minus 10- plus 20-mesh carbon at ambient temperatures were developed and used in the successful application of a cascade design theory. The work was performed as a part of the overall Bureau of Mines research effort to help maintain an adequate domestic supply of metals by making improvements in mineral-processing technology.

Jan 1, 1979

Reduce dust at the auger mine face by modifying airflow patterns, around the minim machine. Approach Limited clearance between an auger miner and the mine root restricts airflow across the face and causes dust rollback. Directional sprays arc used to direct air across the face, thereby reducing dust rollback and increasing dust dilution (fig. 1). Laboratory and underground studies were used to test and optimize effectiveness of the directional sprays. Results of Laboratory Study Laboratory experiments were conducted in a simulated auger gallery equipped with a full-scale mock auger miner and bridge conveyor. A dual curtain configuration was used to direct the, ventilation, which averaged 2,700 cfm throughout the experiment. Testing variables included spray location, pressure, spacing, orientation, and number. Figure 2 shows the optimized directional spray system, also called the auger clearer spray system. The system consists of three sprays mounted alone the intake side of the miner. Sprays arc spaced 16 to 24 inches apart, and angled 30° toward the return side of the miner. The 24-inch spacing moved about 7% more air across the face than the 16-inch spacing; however, it resulted in some additional misting on the return side of the miner. A 30° orientation was more effective than a 60° orientation for moving air across the face and minimizing misting on the return side of the miner. Flat fan sprays arc used because their spray paths arc not obstructed by the top of the miner and mine roof, A 50° fan angle is used to minimize misting on the intake side of the miner.

Jan 1, 1989

By Howard M. Stainer

Jan 1, 1963

By Howard M. Stainer

[Cover Page]

Jan 1, 1963

By L. B. Pankratz

The Bureau of Mines conducted heat-content measurements above 298.15° K for dehydrated analcite (NaAISi2O6) to 1,000°K, kaliophilite (KA1Si04) to 1,800° K, and leucite (KAlSi206) to 1,800° K. Heat content and entropy increments were tabulated, and the heat content data, were given in equation form. A first order transition was noted for kaliophilite near 810° K with a heat absorption of 160 cal/mole. Leucite had a second order transition which became complete near 955° K. In this transition a crystal change occurred from tetragonal (low-temperature form) to cubic (high-temperature form).

Jan 1, 1968

By E. G. King

This paper reports measurements of low-temperature heat capacities and entropies at 298.15° K. of two copper ferrites (CUFe204 and CU0.75Fe2.2504). These substances, which occur in copper-smelting slags, have not been sujected to any previous direct thermodynamic investigation. The two copper ferrites are spinel minerals of the variate class. In previous investigations similar data were obtained for 13 other spinel minerals -7 of the normal class and 6 of the variate class. The entropies at 298.15° K. of these minerals have been compiled and revised as necessary in the light of present knowledge regarding structural randomness; entropy values, recommended for use in thermodynamic calculations, are listed.

Jan 1, 1959

By Thomas V. Falkie, R. Venkataramani

The empirical nature of this investigation required measurements of variables under operating conditions in underground coal mines. The variables to be measured were based on the postulated character¬istics of the loading function, as described in the previous chapter. One class of variables presumed to influence the loading function are geological variables. Accordingly, the sites for data collection were selected in different bituminous coal seams at dispersed locations in order that variation in geological conditions would exist. Seven mines in central and western Pennsylvania and one mine in northern West Virginia were selected as data collection sites. Five different coal seams were represented by these mines. The remaining classes of variables - geometric, mechanical, and procedural - were measured as they occurred in the mines. A description of the measurements, and the conversion of these measurements to forms which could be-analyzed for effect on the loading function is given. Mining Dimensions At the underground working face, the following dimensions were measured: a. Thickness of coal excavated. b. Thickness of shale excavated. c. Total height excavated. d. Width excavated. e. Depth of penetration of each machine cut. With the exception of the last of these dimensions, all were measured

Jan 1, 1972

By Foster Fraas

In this Bureau of Mines report, use of the photoemission of electrons to produce electric charges for the electrostatic separation of sonic dispersed minerals, which had previously been ground to pass a 43µ-opening sieve, is demonstrated. It appears that many of the oxides, carbonates, sulfides, and arsenides will respond to photoemission. Minerals least responsive are the oxides of silicon, the oxides of aluminum, and minerals that have a high concentration of these oxides. Although several synthetic ore mixtures did not yield to complete separation in a one-stage operation, it is probable that preliminary neutralization of the initial electric charges produced by powder dispersion will provide complete separation. That the separation can be carried out in air and without the use of reagents or heating, which are required in the present practice of electrostatically separating coarse granular feeds, is of special significance.

Jan 1, 1972

By Kenneth M. Earl

The purpose of this investigation was to obtain subsurface information on the John Burdette barite-fluorite deposit, Garrard County, Ky. The deposit was intersected in each of five inclined diamond-drill hales aggregating 1,163 feet. All holes were drilled from the hanging wall of the deposit; the inclinations varied from minus 41° to minus 75°. Disseminated metallic sulfides were noted in the drill cores from holes 1, 2, 4, and 5. The deepest drilling was hole 5, which intersected the deposit at approximately 490 feet down dip. Visual inspection of the cores did not indicate mineralization of economic importance; therefore, no chemical analyses were conducted. Condensed logs of diamond-drill cores are included in this report. All drill cores were shipped to the Bureau of Mines core library in Minneapolis, Minn., for future reference,

Jan 1, 1959

By Richard J. Mainiero, Sapko, Marcia L. Harris

Since 1988, there have been thirteen documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through near surface strata into structures or other enclosed spaces as a result of nearby trench blasting or surface mine blasting. From these incidents, there are thirty suspected or medically verified CO poisonings and one fatality associated with these incidents. To better understand the variables contributing to this hazard, the National Institute for Occupational Safety and Health (NIOSH) carried out a small-scale field study to identify key factors that may contribute to the migration of CO through the ground. NIOSH conducted single-hole heavily confined experimental test shots to measure the radial pressure pulse as it propagated through surrounding monitoring holes to determine if a relationship existed between the pressure pulse and resulting CO measurements afterwards. NIOSH also monitored blasts at an airport construction site. Following the detonations, the concentrations of CO, nitric oxide (NO), and nitrogen dioxide (NO2) were monitored for several days in the surrounding satellite holes. The peak CO measurements relative to distances from the shots were compared. Pressure histories and peak particle velocities (PPV) were measured at monitoring boreholes. It was found that the differential pressures recorded within the boreholes give some indication as to the likelihood of CO appearing, whereas the PPV measurements do not seem to be as good an indicator for potential CO migration. In this limited study, changes in barometric pressure had very little influence on removing the trapped detonation products, whereas applying a vacuum to the monitoring holes was effective in reducing the entrapped CO concentration.