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By Maria I. De Rosa

Table 55 and figure 19 show the number of fires and fire injuries for stone mills by state during 1990-2001. Table 55 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 118 fires occurred in 33 states. Seventy-six of the fires caused 82 injuries (including 8 fires and 6 injuries involving contractors). The yearly average was 9.8 fires and 6.8 injuries. The Ewhr value was 873 x 106 hr (In = 0.019), and the LWD value was 1,911. Missouri had the most fires (16 fires and 9 injuries), followed by Pennsylvania (15 fires and 14 injuries), Michigan (9 fires and 5 injuries), and Virginia (7 fires and 5 injuries). Of these states, Virginia had the highest injury risk rate value (In = 0.09 1). Table 56, partly illustrated in figure 20, shows the number of fires, fire injuries, risk rates, employees' working hours, and lost workdays by time period. The number of fires and fire injuries decreased during most of the periods, with a sharp increase during the last period. The number of employees' working hours increased throughout the periods. The In values follow patterns similar to those shown by the injury values. Tables 57-63 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 21 shows the major variables related to fires for 1990-2001. Table 63 shows the fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By Robert P. Vinson, Kissell. Fred N., Edward D. Thimons

"The Bureau of Mines investigated the presence and extent of methane accumulations in mine roof cavities using a full-scale mine model. Methane was released at a constant rate into the roof of a cavity built onto a 700-ft wind tunnel. Two box-shaped roof cavities were used in the study: one had a volume of 114.7 cu ft; and the other had a volume of 57.3 cu ft. Methane concentration was measured at 28 sampling points in the cavities using 21 different combinations of gas emission rates and air velocities. Brattice hung in the cavity helped reduce methane concentrations without auxiliary ventilation. It was also found that the effective ventilation rate increased by a factor of 40 in the large cavity and by a factor of 20 in the small cavity when air velocity was increased from 100 to 600 fpm.INTRODUCTIONAny location in a coal mine where 5 pct or more of methane is present constitutes a potential site for an explosion and roof cavities are likely locations. Unfortunately, little is known about the buildup of methane in roof cavities. Some research has been done using scale models where no air flows past the cavity so that methane disperses only by diffusion (5) 4 a rare situation in mines.No known cavity-model investigations have been made that simulate air and methane flow conditions normally encountered underground. These Bureau of Mines studies were undertaken to determine the extent and manner of methane buildups in coal mine roof cavities with air velocities in the range normally found in coal mines and with various methane emission rates."

Jan 1, 1978

By M. D. Schlesinger

Mercury exists in coal at very low levels; the structure of coal, the vapor pressure of mercury, and its almost universal occurrence introduce unusual problems into the analytical methods. Round-robin analyses by several laboratories, each using its own techniques, indicate that the average mercury content of coal is about 0.2 part per million. Some western coals are as low as 0.05 ppm.

Jan 1, 1971

Preventive maintenance practices are listed in the manufacturers' instruction books. In general, equipment that requires frequent and extensive preventive maintenance is generally the most costly. The manpower spent on these frequent trips to remote areas is such that it is usually better to invest in a more costly system which requires little preventive maintenance. The best preventive maintenance for the system is a good installation. 7.2 Preventive Maintenance and Inspections With any system, periodic inspection is required because of the corrosive atmosphere and adverse conditions that exist in underground mines. These inspections can spot potential trouble in the system. Repair or replacement at that time averts the possibility of losing effectiveness of all or part of the system. 7.2.1 Cables Approximately once per month all cables in the communications system should be inspected for kinking, chafing, cracking, wear, stretching, or other signs of physical abuse. Particular attention should be paid to cable glands at the entry or exit points to the various units in the system, where the cable goes around sharp corners, in the vicinity of holding cleats which may be clamping the cable too tightly causing potential damage, and across the areas where the cable is exposed to physical damage from outside sources, such as equipment or falling objects. If a cable is damaged, it should be replaced as soon as possible. It is mandatory that the ground leads and connections to carrier current phones be thoroughly inspected and maintained in good condition, since considerable hazard may exist to the operator or equipment if a ground connection is broken. 7.2.2 Pager Phones The most readily available test set to determine if a pager telephone is operating correctly is the pager phone itself. The following physical check of the system can be performed at any phone station. 7.2.2a Listen Circuit Remove the handset from its cradle and listen to determine if the circuit is functional, as indicated by the presence of noise or conversation on the line. If no noise or voice signals are present at the handset receiver, take the following corrective action: 1. Operate the handset press-to-talk switch several times. Any corrosion on the contacts of this switch may cause a receiver to be temporarily inoperative. Repeated operation may clear the condition. 2. Open the cabinet and see if the battery cables are properly connected and are making firm contact. Check the handset cable and its connections in the cabinet of the pager phone, and see if there is any evidence of a break in the cable, corroded contacts, or poor connections. 3. Remove the handset receiver earpiece by unscrewing it counterclockwise (to the left), and remove the receiver from the socket. Examine the handset cavity; in some units, a patch of cotton batting or floss is used as a barrier to reduce acoustic feedback in the handset. If the cotton patch has absorbed moisture, remove it and replace with a crumpled ball of soft rubber, stuffed just far enough into the handset so it will not touch the receiver or switch terminals. 7.2.2b Page Circuit and Talk Circuit Push the page switch, squeeze the handset press-to-talk switch, and call any other phone. Release the page switch

Jan 1, 1984

By E. H. Denny

A most interesting safety record has been made by the Colorado Fuel and Iron Co. s. Robinson ho. 1 mine located at Walsen, Cola. Mr. J. L. McBrayer has been superintendent of the Robinson No. 1 and 2 mines for the past 2 1/2 years, and Mr. David Muir has been foreman of the Robinson No. 1 mine since June, 1913. The last fatal accident at Robinson No. 1 mine occurred on July 27, 1915, and the tonnage produced at this mine since July 28, 1915, has been as follows:.

Jan 1, 1929

By Jeffrey B. Osmint

The Bureau of Mines Information and Analysis Directorate collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The Bureau's data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1991

By L. C. IlsLey

Figure 1 is a reproduction of a chart recently prepared by the Bureau of Mines at its Pittsburgh Laboratory to show the Bureau's approval work in connection with electrically operated mining equipment. Nearly 27 years of approval work, covering 346 approved units, are shown on this chart. These approvals are arranged according to year of approval and the manufacturer to whom approval was granted. Forty-five manufacturers are represented, and a scheme of using various colored tabs permits the following subdivision of the equipment: Cutting machines, loading machines, conveyors, battery-operated locomotives, battery-operated power trucks, drills and drilling machines, rock-lusting machines, pumps, room hoists, air compressors,, and miscellaneous, The greatest number of approvals granted to a single manufacturer is 80; the next highest is 65, and the third is 49. Several manufacturers have been granted only a single approval. The chart shows all approvals granted for, motored equipment. Some of these units have since become obsolete, and a few are used to a very limited, extent if at all.

Jan 1, 1941

By A. L. Engel

The sample of ore on which the work described in this paper was done came from Mina Oriente, Carrizal Bajo, Provincia de Atacama, Chile, South America, and was sent at the request of the Chil.ean Government through the Foreign Minerals Division of the Bureau of Mines. This ore had been tested locally for treatment by flotation and cyanidation without satisfactory results. An additional difficulty was the absence of water near the ore deposits, so that in any treatment method considered the water requirements would have to be very low. It was desired to develop a practical method of recovering the gold and, if possible, the copper in the area. No data of previous investigations were made available. The sample received was mostly quartz, highly brecciated, with limonite and hematite in the fractures. Copper occurred as malachite and azurite, also in the fracture s and to a slight extent as a stain in the quartz. Some fine-grained pyrite with a little arsenopyrite occurred within the quartz. An occasional grain of chalcopyrite was observed. No free gold was seen during examinations of the ore, but amalgamation indicated that some was present.

Jan 1, 1949

By W. P. Diamond, B. M. Bench, C. M. McCulloch

This Bureau of Mines report describes photolineaments obtained from stereoscopic examination of vertical aerial photographs and by the Ronchi grating study of aerial photoindex sheets. The photolineaments are compared with the trends of oriented fracture systems procured by measuring the compass direction of joints in bedrock. The relative reliability of the methods is shown, and the results are presented in graphical, tabular, and written form. Analyses of field measurements of strikes of bedrock joints in the project area indicate for the most part two intersecting sets of major joints oriented N 76° W - N 15° E, and N 57° W - N 27° E. The analyses of lineaments determined by stereoscopic examination of aerial photographs show dominant trends of lineament zones of weakness to be an average of N 65° W - N 20°E. Analysis of lineaments found by Ronchi grid viewing of aerial photoindex sheets indicate dominant trends of N 70° W - N 27° E. The three methods give similar findings and verify the work of previous authors. The Ronchi grid method is a useful guide, but it cannot be substituted for the two more painstaking methods.

Jan 1, 1977

By Eric E. Cather

In 1981 the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral survey of the 5,100 acre (2,065 ha) Rubicon RARE II area (No. 5026) in the El Dorado National Forest (fig. 1). Work by the Bureau of Mines indicates that potential for mineral resources in the area is low. Samples from small gravel deposits along the Rubicon River and from favorable structures in the area contained smart amounts of economic minerals. A Tertiary river channel near the north area boundary contains gold values as much as $137.60 per cu yd ($180 per cu m) [(gold at $400 per troy oz ($12.86 per g)]. The channel does not cross the study area. Energy resource potential, including oil, gas, or geothermal, does not exist in this geologic environment.

Jan 1, 1982

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

6. Development of Mine Sealant Material Systems 6. 1 Introduction The preliminary evaluation of material systems described in Section 3 led to the selection of the following four promising systems for further development: System A: Aggregate, Fly Ash System System B: Aggregate, Fly Ash, Urethane Foam System System C: Aggregate, Bulkhead, Light Expansive Concrete System D: Aggregate, Self-Supporting Thick Slurry Preliminary laboratory tests indicated that the building of effective bulkheads from one borehole would be extremely difficult. Two extra boreholes would be required adding to the overall cost of the system and making the system less attractive. Tests with light expansive concrete showed that bulkheads would be required, the material would not support itself. As a result, further development of this system was terminated. Foam concrete was selected as the most suitable material to be developed into a self-supporting, rapid-setting slurry. A laboratory investigation of its use for mine sealing was conducted during this program; the results are summarized in Section 6. 5 and details of the laboratory program are presented in Appendix B.

Jan 1, 1973

By Jay F. Colinet, John A. Organiscak

In This Chapter [Which dust source to address first How much air and water are needed Keeping dust out of the walkway Moving workers upwind Dealing with the stage loader-crusher Gob and wing curtains to aid airflow The shearer-clearer system Modified support movement practices and Dust control for future longwalls ] Controlling longwall dust is not easy. Longwall production levels are high, and there are several different sources of dust to contend with. If dust levels are high, the initial effort should be devoted to finding which source is the cause. Then, efforts to reduce dust can be concentrated where they will have the most impact. To control dust at longwalls, a large amount of ventilation air and spray water must be used. The water must be sprayed correctly so as not to blow dust into the walkway. Techniques to change local airflow patterns can be helpful. The shearer-clearer, as well as gob and wing curtains, are examples of such techniques. DECIDING WHICH DUST SOURCE TO ADDRESS FIRST [If a longwall is out of compliance with dust standards, knowing where the extra dust is coming from helps to get back in compliance quickly.]

Jan 6, 2003

By J. Schlocker

The present emergency has greatly stimulated interest in the light metals - aluminum and magnesium - owing to their extensive use in airplane construction. The $63,000,000 plant being erected in the Las Vegas Valley by Basic Magnesium, Inc., under the auspices of the Defense Plant Corporation,

Jan 1, 1942

By C. A. Komar

Hardness, tensile strength, and impact toughness of dry and brine-saturated sandstone specimens were measured at ambient, cryogenic, and elevated temperatures as a measure of the relative stability of reservoir rocks for subsurface disposal of liquid wastes. Hardness measurements were inconclusive. Tensile strength and impact toughness were significantly higher at -320° F than at ambient temperature, but were relatively unaffected at 700° F. Impact toughness was reduced by subjecting the specimens to three cycles of rapid temperature changes (thermal shock) over a 1,000° F range. Tensile strength of brine-saturated sandstone was less than that of dry sandstone. Based on results of the tests, reservoir sandstone likely would be stable if exposed to extreme temperatures of liquid wastes, although rapid changes in waste temperatures should be avoided.

Jan 1, 1971

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

The data for Test I1 describes an underground bituminous coal mine operating in a 72 inch seam, with an estimated production rate of 4,257,000 tons per year. The system includes 15 continuous mining sections, conveyor belt haulage, and a rail network for supply and personnel transportation. The following section includes the input data sequence, annual cost report, and cash flow analysis "report for this data set.

Jan 1, 1975

By Bruce I. Thomas

In 1943, the Bureau of Mines investigated the occurrence of cassiterite in the gravels of Morelock Creek which flows into the Yukon River 32 miles east of the confluence of the Yukon and Tanana Rivers in central Alaska. Samples of the gravels were obtained by churn drilling test pitting, shaft sinking, and open-cut mining. The gravels along Morelock Creek are about 6 feet in depth and covered with about 2-1/2 feet of overburden. The overburden is frozen, but the underlying gravels are not. Cassiterite, with gold and other heavy minerals, is usually concentrated in the first 2 feet of' gravel above bedrock and in some places penetrates into joint planes in the bedrock. The various methods of obtaining samples are discussed, and drill logs and analyses are tabulated in this report.

Jan 1, 1948

Remotely monitor overburden response to longwall mining using time domain reflectometry (TDR) and a combination of hardware and software, as part of the U.S. Bureau of Mines (USBM) program to characterize subsidence. Background TDR was developed in the 1960's as a method to locate, discontinuities in coaxial transmission cables. In this method, voltage pulses sent along a cable are reflected by cable defects. The pulse reflections are used to determine the type and magnitude of the defects. The TDR concept was extended to material property measurement by embedding cables into particular materials and evaluating the cable's dielectric behavior as material properties were modified. This technique was adapted by the USBM in 1978 for use in monitoring rock movement during underground mining. The same concept is utilized today. A coaxial cable is grouted into a rock mass that is expected to deform. Progressive rock movement causes the cable to deform, as shown in figure 1, and changes to occur in the cable's electrical properties, which then produce changes in TDR reflection signatures. The technology has advanced to the point where it is now possible to distinguish shear deformation from tensile deformation and to quantify rock mass displacements by analyzing the TDR signatures.

Jan 1, 1995

By R. F. Tenney

No detailed information has been published heretofore on the performance of small industrial-type anthracite stokers in building-heating service, apparently because of the difficulty of comparing the performance of one unit with that of another over an entire season's operation. Studies of competitive heating fuels have been similarly handicapped, and attempts to compare fuels are seldom technically sound in this investigation, the performance of a 60-in. Losch4 stoker burning rice-size anthracite in a standard commercial boiler was observed during a 4-month winter-spring season. It was used to heat two buildings at the Bureau of Mines' Anthracite Research Center at Schuylkill Haven, Pa., with the customary type of automatic pressure-range control. Attendance was limited to inspecting, fuel weighing, data recording, and ash removal. Results were computed daily and grouped by weekly periods to minimize daily irregularities. The same stoker-boiler unit had already been tested in a series of American Society of Mechanical Engineers (ASME) test code runs, with the stoker running continuously and with other conditions well stabilized A comparison of results from the code test and the building-heating tests provided information not available in the past for a single stoker unit, assisted in analyzing heat losses not computable in a cyclic operation, and established a basis for evaluating stoker performance in heating service.

Jan 1, 1963

By John C. Holtz

The Bureau of Mines studied air contamination caused by diesel exhaust in a 10,000-ft ventilated tunnel. Sequential air samples were taken at the ends and middle of the tunnel during an operating cycle. Observed and calculated results for carbon dioxide, carbon monoxide, and nitrogen oxides were essentially in agreement. Nitrogen dioxide was present only in trace amounts. It was found that contamination was related to the volume of ventilating air, the number of haulage trips, train speed, and engine load.

Jan 1, 1968

By N. A. Gokcen

Equilibrium partial pressures of gaseous HCl and H2O over aqueous binary and ternary solutions of HCl and AICls were calculated or estimated in the range of 20° to 110° C, and up to saturation with AlC13?6H2O. The results were extended to solutions containing less than 10 wt-pct FeCl3 by assuming that FeCl3 and AIC13 are equivalent on the molar basis, since both salts have trivalent cations with a cammon anion. The ionic activity coefficient of HCl and the equilibrium constant for dissolution of gaseous HCl were also computed. This research is part of the effort by the Bureau of Mines, U.S. Department of the Interior, to provide thermodynamic data to expand the technology base relevant to the extraction of alumina from nonbauxitic domestic raw materials.

Jan 1, 1980