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By E. C. Tarpley

The Federal Bureau of Mines has studied solvent extraction as a means of concentrating the mineral components in coal. Solubilities of a number of American coals were determined using abietic acid as a solvent. The effect of rank on solubility was investigated, and maximum solubility was found with coals of intermediate rank. Vitrinite is the most soluble petrographic component; fusinite, micrinitc, and exinite are nearly insoluble. Spore exines also have a low solubility. Abietic acid is a hydrogen donor and reduces pyrite to ferrous sulfide. Mild hydrogenation of high-molecular-weight fragments of the coal structure to those of lower molecular-weight probably contributes to the solvent action. Even where solubility of the coal substance exceeds 90 percent, contamination of the mineral matter with coal makes identification of the mineral components difficult. Further separation might be possible by the application of float and sink techniques to the residue. INTRODUCTION Work n the solvent extraction of coal is conducted to recover commercially useful products and to characterize coal;. and obtain information on their structure. Some coals, particularly those of low rank, contain waxes, resins, and humic acids which can be removed by solvent extraction and find varied industrial uses. In World War II, solvent extraction of coal was conducted on a commercial scale in Germany to obtain a low-ash feed material for hydrogenation and to produce electrodes carbon for the aluminum industry.4 5/

Jan 1, 1960

By W. J. Johnson

This report presents the Phase I progress in the development of a Radar Coal Thickness Sensor (RCTS) being conducted by Boeing Aerospace and Electronics for the Bureau of Mines. A method is developed for measuring both the dielectric constant and depth of the coal shale interface using a modified UHF network analyzer and antennas in proximity to the surface of the coal. Both bistatic and monostatic systems, are compared. The algorithm technique uses synthetic range gating for clutter rejection and full polarimetric scattering matrix techniques to extract the dielectric constant and depth to sub-wavelength accuracies. Tests were run both in the lab and in a coal mine to build an error budget and demonstrate a validation of the model. The development of a prototype radar suitable for coal mine robotics is specified.

Jan 1, 1990

To improve electrical safety and lengthen light bulb life on trolley haulageways. Approach A resistor inserted in series with each pair of light bulbs, decreases the voltage applied to the bulbs and eliminates heavy arcing when voltages rise. How It Works Under certain conditions, incandescent light bulbs connected directly to a 300-volt d-c trolley wire can be a hazard, particularly during weekends when electrical equipment is nut in use. When little electrical power is being used, the voltage (on the trolley lines and at the substation) can rise to a value which will destroy the bulb filament, cause arcing, and damage the bulb holder. In one coal mine where light bulbs in certain locations fre¬quently failed, the problem was overcome by inserting a 100-ohm, 50-watt resistor in series with each pair of light bulbs. The light bulbs are rated at 300-volts and 100-watts. Figure 1 shows the light bulbs and resistor circuit. This resistance was added in order to reduce the current through a short circuited bulb holder, from several hundred amperes to a much safer value of 3 amperes. However, the resistor in series with each pair of light bulbs, also reduces the voltage across the lighted bulbs to approximately 240 volts during periods when the trolley line voltage is up to 300 volts. With this arrangement, no light bulb failures occurred over a 6-month period. The resulting light reduction has not been objectionable.

Jan 1, 1976

By Dale Marcy, Pamela L. Drake, Kevin Ashley, Kyle J. Hazelwood

National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Strong anion-exchange solidphase extraction (SAE-SPE) is then used to separate CrVI from trivalent chromium and other interferences. Portable spectrophotometric measurement of CrVI is then conducted using the 1,5-diphenylcarbazide (DPC) method. However, it has been found that the ammonium extraction buffer does not dequately bring insoluble CrVI compounds into solution during the UE process. Thus, it was deemed necessary to modify the field method so that it would provide acceptable recoveries for insoluble CrVI compounds. To this end, a more alkaline extraction solution—sodium carbonate/sodium bicarbonate buffer—was investigated. The modified procedure using the highly alkaline extraction solution was demonstrated to be compatible with SAE-SPE cartridges when determining insoluble CrVI in air filter samples. It was found that the carbonate/bicarbonate buffer was equally effective for complete dissolution of both insoluble and soluble forms of CrVI. Furthermore, the modified procedure met desired performance criteria established for air sampling and analytical methods. Keywords: field method, hexavalent chromium, insoluble chromates, on-site analysis, sample preparation,workplace air

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 11 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFCUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION. IN THIS RUN, THE ORIGINAL VENTILATION NETWORK HAS BEEN MODIFIED TO INCLUDE NEW INTAKE AND RETURN AIRSHAFTS AT THE WEST MAINS.

Jan 1, 1977

Produce an annotated bibliography to serve as a comprehensive source of published information available on the use of soil amendments in coal mine reclamation and the characterization of coal mine soils. The Problem There is a substantial amount of information available tin coal mine reclamation and revegetation, particularly on the use of soil amendments to ameliorate site conditions and aid vegetation establishment, growth development, and productivity. Additionally, site characterizations based on chemical, physical, and mineralogical properties have been thoroughly researched. This information, however, is widely disseminated throughout various professional and scientific journals, State and Federal documents, proceedings of conferences, theses, and other technical writings. A critical need exists for a comprehensive and up-to-date summary of published information concerning the uses, methodologies, and types of soil amendments that arc necessary for reclamation success.

Jan 1, 1991

By Sivalingam Jeevan, R. L. McConnell

Ground check monitors may be made in several configurations. Each type has unique characteristics and provides different safety attributes when applied to different mine situations. In this paper, the monitor types are discussed in relation to the mine situations. It is shown that the selection of the monitor type can have a significant effect on the safety of the resistance grounded power system. The options are discussed, and the conclusion is drawn that only one monitor configuration can provide maximum safety. Unfortunately no monitors of this configuration are presently available. In addition, when the monitor capabilities and ground wire configurations are considered as a system, it can be shown that certain configurations will lead to maximum safety. This work was supported by U.S. Bureau of Mines grant G0144138.

Jan 1, 1979

By L. C. Marchant

Results of detailed analyses of four cores from the Threemile Canyon area in the P. R. Spring tar sand deposit in Utah are reported by the Bureau of Mines. The cores were obtained by the Utah Geological and Mineralogical Sur-vey as part of a l7-corehole evaluation program in the P. R. Spring, Hill Creek, and Rim Rock tar sand deposits. Average properties of the oil zone in the Threemile Canyon area as deter-mined from these cores are as follows: Oil saturation, 67.4 pet of pore volume; porosity, 29.2 pct; permeability before oil extraction, 133 millidarcies; and permeability after oil extraction, 2,855 millidarcies. Average net thickness of the oil zone is 23.8 ft and average depth to the top of the oil zone is 189 ft.

Jan 1, 1974

Provide an accurate, simple, alternative means of evaluating the safety of mine electrical ground systems which has little or no negative impact on mine productivity. The Traditional Evaluation Method The Code of Federal Regulations requires all mines to safely ground their power systems to earth. Effective earth grounding reduces shock hazards to mine workers operating electrical equipment, protects equipment from damage by voltage transients, and provides a means of detecting and locating ground faults. Once an earth ground bed has been constructed, its level of resistance has traditionally been used to gauge the safety of the entire grounding system. Bed resistance measurements are normally performed using a ?fall of potential? technique with a current return electrode placed at a remote location, If the resistance measured is acceptably low, then the bed is assumed safe.

Jan 1, 1985

By R. Unger, L. Mallett

The use of virtual reality (VR) technologies to train miners is an evolving area in research and development. In July 2006, representatives of 14 international organizations met to discuss current VR-related efforts and explore ways to employ VR in the future. This paper gives an overview of the various approaches presented at the meeting and discusses directions for future implementation. An example of a training package that teaches mine map-reading skills is presented. The meeting was the first step to building collaborations for furthering VR applications for mining. Planning has begun for a 2008 meeting open to broader participation. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

By Ann G. Kim

Methane in coal constitutes a serious hazard during mining. Draining the methane from large blocks of coal in advance of mining is an effective method of improving the safety and efficiency of coal mining. Because of the similarity of the two gases, drained methane can be recovered and added to pipeline supplies of natural gas. To effectively apply advance drainage techniques and recover drained gas, a gross estimate of the methane content of coal is necessary. Using data from previous investigations, the virgin reserves of the Pittsburgh coal in the central and southwestern parts of Washington County, Pa., are estimated at over 1.5 billion tons, with a methane content of 50 to 100 fts/ton. The Pittsburgh bed in this area of approximately 265 mi2 contains over 130 billion ft3 of methane.

Jan 1, 1974

By D. L. Paulson

The Bureau of Mines is investigating pyrometallurgica1 and" chemical methods to recover valuable constituents from metallurgical dusts and slags. Under this program a technique was developed to recover iron from molten copper smelting furnace slags by carbon injection. Slags from gas-fired reverberatory and electric copper smelting furnaces were treated in an 800-kva electric-arc furnace by injecting coke breeze into the bottom of the molten bath. Over 95 pct of the iron and over 90 pct of the copper contained in the smelting furnace slags were recovered, while up to 85 pct of the carbon injected into the system was utilized. It is anticipated that the metal product containing approximately 95 wt-pct iron and 2 wt-pct copper will be a satisfactory medium for recovering copper by cementation.

Jan 1, 1977

By George S. Koch

Several methods of calculating ore grades by diamond-drill sampling in the Homestake mine, Lead, S. Dak., have been evaluated by statistical analyses of assay data. The natural distribution of gold particles, partly masked through sampling and assaying procedures, is probably lognormal. As a consequence of the gold particles being clustered rather than randomly distributed within the ore bodies, (1) more mine samples are needed to obtain a specified precision of mean grade than the number predicted by the standard-error-of-the-mean law; (2) the variance of gold values is not inversely proportional to sample volume, and, therefore, small-diameter drill core yields samples nearly as good as larger diameter core; and (3) sampling at 5-foot intervals provides nearly as good results as sampling at shorter intervals.

Jan 1, 1971

By Larry G. Stolarczyk

This report deals with the creation of an efficient method to determine if command, control, communication and monitoring (3cm) equipment in coal, metal and non-metal mines is susceptible to Radio Frequency Interference (RFI) from the Medium Frequency (MF) radio communications system. A qualitative and quantitative RFT test plan was developed for in-mine and laboratory evaluation of the equipment. The laboratory testing was accomplished using the TEM Test Chamber. Detailed information on the Test Plan and the TEM Test Chamber is included. During in-mine testing of the MF System some underground equipment malfunctioned when the transmitter's radiating antenna was in close proximity. Electromagnetic Compatibility (EMC) testing was done on three levels; Component (circuit or box), subsystems and system. Nine tables are included which show the results of testing various equipment for RFI.

Jan 5, 1986

By Kenneth J. Miner

Pittsburgh bed and Lower Freeport bed coals were tested in the U.S. Bureau of Mines two-stage froth flotation pilot plant, which utilizes a new flotation process to remove pyritic sulfur. The process consists of a first-stage coal flotation step to remove coarse, free pyrite and other refuse in the tailings. The clean coal froth concentrate is then repulped and treated with a coal depressant, a pyrite collector, and a frother to selectively float the remaining pyrite in a second stage. Results in the pilot plant were excellent, comparing well with those obtained in laboratory batch tests. That is, about 70 percent of the pyrite present in the Pittsburgh bed coal and about 90 percent of the pyrite present in the Lower Freeport bed coal were removed with excellent final clean coal recoveries.

Jan 1, 1973

By C. E. Jordan

Domestic cobalt resources are relatively large, but low grade. The full potential for cobalt production from domestic sources is at least 19.4 million lb of cobalt per year exclusive of offshore resources. A summary of the cobalt processing technologies for the major domestic resources is presented in this Bureau of Mines report. The processing technologies for the Blackbird, Madison Nine, Duluth Gabbro, iron ore pyrite, laterites, and manganese sea nodules are nearly complete, but the economics are not favorable. Research on these resources should be limited to approaches that promise to cut the total processing costs by at least 50 pct. The most promising sources of cobalt are the spent copper leach solutions and siegenite from the Missouri lead ores. Research on cobalt processing from these two sources needs to be completed.

Jan 1, 1988

By William C. McBee

Prompted by forecasts of a sulfur oversupply, the Bureau of Mines, U.S. Department of the Interior, is conducting research on potentially large-scale uses of this commodity to extend or replace such construction materials as asphalt, cement, and mineral aggregates. Through these efforts, paving materials have been developed in which sulfur replaces up to 50 pct of the asphalt normally present and which can be prepared and placed with existing mixing and paving equipment. Laboratory properties and design methods for this direct mixing process are described along with properties obtained on small-and large-scale field demonstration projects. These properties are compared with those obtained from control materials prepared without sulfur additions. Monitoring for toxic gases during laboratory and commercial mixing and paving operations is discussed also.

Jan 1, 1978

By R. V. Ramani, V. T. Burgos, J. A. McClay

The systems contributing to the cost analysis, and the flow of data input and output related to these systems, are brought into focus in Figure 6. The various sub-systems of the Master Design Simulator provide the raw operating data basic to the cost model which, operating independently, accumulates the raw input, assigns costs to this data by standard or modified costing procedures, manipulates the costs into standard formats and outputs the data for managerial evaluation. Cost Modeling Direct costing methods are not complex in the sense that elemen¬tary arithmetic is employed using the same basic relations for each cost category. The basic cost model relations described above are illustrated in Figure 7. The greatest difficulty encountered in the transition from a dy¬namic systems simulation model to a costing model is the time frame of the input and output data. Dynamic simulation models utilize a small time increment, on the order of seconds or fractions of seconds, to analyze system operations and interactions. On the other hand, for cost computation and reporting, the smallest relevant time unit is the shift, with reporting periods expanding to days, weeks, months, and years. Complications arise in the accumulation of data for the various report periods due to the use of the Gregorian calendar by modern so¬ciety. The potential for simulation for the life of the mine, possibly in excess of 50 years, increases the complexity of the costing process

Jan 1, 1975

By Ira E. Sproat

The question "Why can not American kaolins be substituted for English china clay?" has been asked time and time again, and more often since the beginning of the present war in Europe, which has threatened to cut off the supply of European clays imported from abroad. The answer to this question has invariably been, that the domestic kaolins are not as pure and uniform in composition as the imported clays. This demand for white-burning American clays is of such economic importance that it was considered advisable to determine whether some of our vast deposits of impure white clays could not be refined sufficiently to permit their being substituted for the foreign materials. Up to the present time mechanical principles only have been applied in the refining of kaolins, but in order to keep pace with the increasing requirements for better quality and uniformity of product, the application of the principles of colloidal chemistry is necessary. The investigation described in this report was carried on to deter- mine the practicability of applying technical control of clay disperse systems to the refining of kaolins and the utilization of the prepared clay in the manufacture of vitreous china and wall tile. It is hoped that this report will prove a stimulus to the clay- washing industry; will point out a method of refining certain Amer- ican clays, and will lead to the substitution of domestic kaolins for imported china clays by manufacturers of high-grade ceramic wares.

Jan 1, 1916

By N. A. Caspero, W. E. Eckard, W. T. Wertman

A thermal oil-recovery experiment was conducted in the Venango First sand, Goodwill Hill oilfield, Warren County, Pa., about 10 miles northeast of Titusville. The Quaker State Oil Refining Corp., Bradford, Pa., performed the experiment with assistance from Sinclair Research, Inc., Tulsa, Okla., and the Federal Bureau of Mines. The Goodwill Hill field was discovered in 1885. Primary-production oper- ations continued until 1930 when an air-gas injection project, which is still in operation, was started. At the location of the combustion experiment, the reservoir is 400 feet deep and 30 feet thick, with wide permeability and porosity variations. The crude oil is typical Pennsylvania Grade paraffin- base oil with a gravity of 43.9° API and a viscosity of 4.55 cp at 60° F. The well pattern for the experiment consisted of 5 producing wells, enclosing an area of 1.28 acres, and a central ignition-injection well. An air-natural gas mixture was ignited in the ignition well on July 29, 1961. Ignition was followed by injection of air and natural gas at various rates. The experiment was suspended January 5, 1962, when it became evident that economic oil production could not be achieved. There was no conclusive evidence that self-sustained combustion was achieved or that combustion increased oil and water production. A slight increase in liquid production was attributed to stripping action caused by the air-injection rates, which were higher than those normally used during air-gas injection.

Dec 1, 1963