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By Terry S. Cory

This report is a comprehensive summary of the results of the propagation measurements program conducted for the US Bureau of Mines under Contract H0366028. Data was gathered in the MF frequency range from a cross sample of six mines representative of the industry having typical wireless requirements. From the raw data which was gathered, a logical method of data reduction is presented which culminates in a set of average attenuation characteristics for all mines visited. These characteristics define a typical MF wireless system when the communication range requirements are known. Direct through-the-earth propagation and the range enhancement mechanism due to coupling on and off conductors are evaluated and related to the planning of a typical wireless MF communications system.

Jan 8, 1977

By M. J. Friedel, D. E. Scott, T. J. Williams

Rock masses in deep level mines are subject to high stresses, which can result in unexpected failure of rock into mined-out openings. Historically, various independent methods have been used to discern the causes of rock bursts and to evaluate stress conditions in rock masses susceptible to violent failure. Personnel from two research centers of the former U.S. Bureau of Mines, Spokane and Twin Cities, investigated a rock burst that occurred in May of 1994 in a rock mass between the 4400 and the 4600 levels of the Sunshine Mine, Kellogg, ID. The team evaluated the current state of stress in the pillar and the most likely cause of the rock burst by studying the seismic history of the pillar, examining the geology, analyzing the available in situ stress data, calculating possible fault-plane solutions for the burst, and performing a seismic velocity tomographic survey. The results of the study showed that post-rock-burst seismicity was concentrated about 15 to 30 m west of and about 15 m above the rock-burst location. The pillar is composed of a very hard sericitic-to- vitreous quartzite of a type rarely found in the mine, but that is often found in other district mines having a history of seismic activity. In situ stress analysis of the pillar and the surrounding rock mass showed a probable stress rotation from northwest-southeast to east-west. Of four fault plane solutions, the most probable was either a left-lateral, strike-slip movement with a compressive principal stress oriented nearly north-south, or a right-lateral, strike-slip movement oriented east-west. Finally, tomographic images showed low-velocity areas (interpreted as areas of low stress) associated with the crosscuts and haulageways, and high-velocity areas (interpreted as areas of high stress) associated with the rock-burst location. High velocities were also found in a planar area oriented in an elongate northeast-southwest direction.

By Karl C. Dean

The Bureau of Mines studied the precipitation of copper from dilute acidic sulfate solutions using shredded automobile scrap in a rotary drum. The tests established that the scrap in the rotary drum precipitated copper faster and more completely than shredded, detinned, tinplate scrap in a launder, with comparable iron consumption. Although power is required to rotate the drum, the faster precipitation and continuous recovery of cement copper are advantages of the tumbler method. Cost evaluation indicates that the rotary drum method, which uses relatively low-cost and readily available shredded automobile scrap, is competitive with the launder method, which uses relatively high-cost shredded tinplate scrap or detinned shredded cans.

Jan 1, 1968

By J. H. Heginbotham

As part of the total metallurgical system to recover metals from secondary resources, the Bureau of Mines conducted froth flotation research, using cationic reagents to recover glass from urban refuse. Batch flotation tests showed that high-quality cullet can be obtained from glass-rich aggregates derived from municipal incinerator residues and unburned refuse. This was confirmed by pilot plant operations treating 350 pounds of flotation feed per hour. Aggregates containing 85 to 90 percent glass were wet-ground to minus 20 mesh, deslimed in two stages, and fed to flotation cells. The glass was selectively floated using an amine collector, usually in an amount under 0.2 pound per ton of solids in the feed. The glass concentrates from the rougher cells were cleaned by refloating two or three times. Over 90 percent of the glass in the deslimed feed was recovered in the cleaned concentrates.

Jan 1, 1978

By Joseph J. Wallace, Lloyd Williams, D. A. Reynolds, James J. Dowd, R. F. Abemethy

"SUMMARY AND CONCLUSIONS1. The investigation shows that the most important beds in Allegany County, from the standpoint of known recoverable reserves are: Lower Bakerstown, Upper Freeport, Upper Bakerstown, Upper Kittraing - less important beds are: Sewickley, Waynesburg, Pittsburgh, and Barton. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated to be 556 million short tons, as of January 1, 1951. Of this total, 304 million short tons is in beds 23 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to permit making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total eat ted reserves.3. Recoverable reserves of coal have been estimated in beds 28 inches and more thick. This thickness is about the minimum now being mined by hand-loading onto conveyors in the Appalachian region. The weighted average recovery for all beds in Allegany County, as determined by this investigation, is 49.8 percent. This percentage is based on the total thickness of coal (less partings 3/8 inch or more thick) in the bed rather than on the thickness of the coal mined. Based on the weighted average percent recovery for all beds in Allegany County, the recoverable reserves are estimated to be 152 million short tons as of January 1, 1951.4. The Allegany County coals are low-volatile bituminous in rank.5. The Allegany County coals are strongly coking."

May 1, 1953

By C. E. Hennig

On January 1, 1960 there were 310 petroleum refineries in the United States, with a crude-oil capacity of 9,901,424 barrels daily, according to the Bureau of Mines' annual survey. Compared with a year ago, this represents a net decrease of three in the number of refineries and an increase of 81,578, barrels per day in crude-oil throughput capacity. Continuing the trend to fewer units with greater individual throughput, the capacity of the average refinery in the United states increased during 1959 from 31,373 barrels per day to 31,740 barrels per day. Compared with the previous year, total crude-oil capacity of refineries on January 1, 1960 was lower in the Appalachian No. 1, Other Rocky Mountain, and Texas Gulf refinery districts. All other districts showed slight increases in capacity. At the beginning of 1960 the industry had under construction facilities that would increase the crude-oil capacity in the United States by 70,947 barrels per day. This was the smallest capacity increase under construction at the beginning of the year since 19460 Included in this construction of additional capacity were two new refineries, one in Michigan and another in Hawaii. In addition, the industry was constructing facilities to replace 50,250 barrels per day of existing crude-oil capacity.

Jan 1, 1960

By John A. Breslin

Three scale models of coal mine entries and mining machines were constructed by the Bureau of Mines to study the effects of ventilation parameters on dust concentrations where mining personnel would be working. A one-fifth-scale model of a coal mine entry with a drum-type continuous-mining machine and a one-sixth-scale model of an entry with a twin-borer-type machine were used as well as a one-fifth-scale model of a longwall face with a double-drum shearer. Methane was used as a tracer gas to simulate respirable dust in the models. The distance of the end of the brattice or tubing from the face was found to be more important than the airflow rate for the drum-type machine. Dust reductions greater than 90 pct were shown to be possible with a secondary ventilation system used with the twin borer and a dust collector mounted on the longwall shearer. Cutting-head speed had a significant effect on concentrations at typical positions of miners with the drum-type machine and longwall shearer but not for the twin borer.

Jan 1, 1976

By Vernon R. Miller

The Bureau of Mines developed and evaluated a detector-sorting device to separate the copper-bearing portion from the barren portion of native copper ores. Small-scale sorting tests were run on minus 1-inch plus 1/2-inch size materials from the following Michigan samples: Winona, Kingston, and Centennial ores, and "poor" rock from the Champion mine dump. Results showed that 60 to 85 pct of the copper was recovered in 9 to 19 wt-pct of the sorted fraction. About 90 pct of the copper recovered was obtained in the first pass through the sorter. For the Kingston and Centennial ores, combinations of sorter concentrates and fines generated during crushing, resulted in recoveries of 93 and 94 pct, respectively, of the total copper in the samples. The combined products constituted about 66 wt-pct of the total sample and allowed the balance to be discarded with only a 6 to 7 pct copper loss.

Jan 1, 1974

By R. H. Sprute

Hydraulic backfill consisting of siliceous mill tailings was successfully dewatered and consolidated by electrokinetics in a field test conducted by the Bureau of Mines at the Star mine, Burke, Idaho. A stope at the 2,000-foot level was filled in such a way that slimes and coarse sand were retained in the scope. Following settlement of solids and decant of surface water, direct current applied between buried electrodes created a firm, dense material in approximately 3 hours. This rapid densification of fine-grained material demonstrated the utility of this method and suggests other applications, particularly in the control of slime deposits that cause serious problems in many deep mines.

Jan 1, 1975

By Samuel W. McNary

In August 1984 the U.S. Bureau of Mines conducted a study of the mineral resource development potential of the Badger Canyon-Antelope Creek area, within the Boulder-Pioneer wilderness study area, about 5 miles northeast of Ketchum, 10. The purpose of this study was to investigate in greater detail an area which was designated by the U.S. Geological Survey (USGS) and the Bureau as having a moderate mineral resource potential for zinc, molybdenum, lead, and silver, and a low potential for copper. One hundred twenty-eight soil samples were taken along a 6,2S0-ft traverse on the ridge separating Badger Canyon and Antelope Creek. 5 Five rock samples were collected from old prospect pits and mineralized outcrops. All samples were analyzed for gold. Silver, copper, lead, zinc, molybdenum, arsenic, antimony, vanadium, and mercury. The metal concentrations in the soil samples along the traverse are irregularly distributed. Samples collected near old prospect pits tend to be high in lead and zinc, undoubtedly a reflection of underlying galena-and sphalerite-bearing quartz veins. All of the copper and mercury values in the soils are less than the detection limit, as are most of the lead, molybdenum, and antimony values. Except for lead and zinc values, the metal concentrations in the rock samples are low. Galena and sphalerite were observed in quartz vein samples collected at the old prospects. The results of the study indicate that the galena-sphalerite-bearing quartz veins and veinlets are too narrow, widely-spaced, and low in metal values to be economic. Low concentrations of metals in the soil and rock samples, combined with the lack of major mining activity in the past, indicate that the area has a low likelihood for economic development.

Jan 1, 1986

By A. A. Giardini

This report represents the results of a literature study on boron nitride and related substances. The purpose of the study was to find Information that might be of value for production of a new, hard modification of boron nitride preferably in single crystal form. The report consists of a review of the major developments in boron nitride research, a discussion of the results, tabulations of physical and chemical properties;, conclusions drawn from the study, and a bibliography.

Jan 1, 1953

By Kenneth B. Higbie

Expenditures to advance scientific technology in general reached an all time high in 1965 with some $22.2 billion estimated to have been allocated by government and industry. Federal Government expenditures were estimated at $15.4 billion, with almost 90 percent of the funds devoted to programs involving defense, atomic energy, and outer space efforts. With this massive effort in the United States and a very impressive effort elsewhere in the world, there is little wonder that many new metallurgical developments were announced in the technical press during the year. No effort has been made to cover all aspects of the industry, but a few of the developments are described in this chapter.

Jan 1, 1966

The head loss data for coal slurries over a range of concentrations and velocities and the laboratory screen analysis were selected as areas for investigation in the data analysis performed. The analysis resulted in the following: (1) Size distributions for the coal used in the horizontal pipeline tests were fitted to the Rosin - Rammler distribution function. Each of the fits was significant. Corresponding Rosin - Rammler parameters were obtained which were introduced into the regression analysis. (2) A regression equation was obtained which predicts the slurry head loss of 1-inch by 0 coal slurries ranging in volumetric concentration from 20 to 40 percent and line velocities from 1 to 14 feet per second as a function of the square of velocity. The addition of the term for concentration in the regression equation did not contribute significantly c head loss.

Jan 1, 1972

Three types of communication systems have become popular in solving communication requirements underground: Loud-speaking pager phones, carrier current phones, and magneto ringing phones. Basically, all three are simply single-channel party line systems. Although these systems are quite reliable, the single channel creates a variety of problems. For example- 1. Since no call is confidential, messages are sometimes purposely made vague, especially if accidents or safety topics are being discussed. 2. A potential user must literally "wait in line" until the channel becomes clear for his use; thus, when foremen have to wait to call in reports or supply requests, this single chan-nel creates a serious productivity bottleneck. 3. In many large mines, there are independent branch lines that must be tied together by a dispatcher, adding further delays to the system. To solve these problems, some mines have installed other phone systems-mostly commercial dial phones in industrial enclosures that offer extra channel capacity and private line features. Others have installed a system that combines both dial- and page-phone features in a single unit. Although these do represent improvements, they do not truly solve the overall problems that face modern mines. Besides extra channels, a communication system should have the following features to enhance productivity and safety: 1. A means of paging a roving miner to alert him that he is wanted on the phone. 2. Wireless-to-wired system interconnects by which a miner can talk on the wired phone system by using a remote portable radio. 3. Remote monitors that alert personnel when there is a toxic or explosive gas buildup. 4. Control interfaces that allow remote control of fans, pumps, or other devices. 5. Transmitters and receivers that can serve as emergency links. 6. Loopback that allows an alternate path of communications if the main path is cut. This chapter focuses on equipment and methods to meet the special communication needs of individuals in various places of the underground mine. The communication requirements can be broken down into four categories: 1. The mine entrance (shaft communication). 2. Permanent and semipermanent locations (shop areas, lunchroom, crusher stations, etc.). 3. Mining areas (the room-and-pillar sections, longwall faces, block caving areas, etc.). 4. Haulageways (tracked trolley haulage, diesel, belt haulage). Methods of implementing systems to meet the communication needs of these areas are described in sections 3.2 through 3.5. Section 3.6 discusses methods of satisfying special communication requirements that exist. Major topics in this category include communications with roving personnel, the isolated miner, and motorman-to-snapper communications. Emergency communication systems are described in section 3.7.Detecting and

Jan 1, 1984

By A. J. Barry

Two methods of testing anchorages of headed expansion-type mine roof bolts were investigated by the Federal Bureau of Mines to determine whether they are acceptable for general use. In both methods a load was applied to a tightened bolt with a hydraulic jack. A total of 80 tests, 40 using each method, was conducted in 4 test areas in 3 commercial coal mines. Electric resistance strain gages were used in all tests to indicate true bolt load as the bolt was tightened and when an additional load was applied with the hydraulic jack. The results indicate that: 1. The relationship between the true bolt load and the jack load will vary according to the test method until the two loads become equal. The bolt load-jack load relationship below this point can be determined only with strain gages. 2. The point at which the two loads become equal can be estimated by noting the load when the hardened washer becomes loose in one method, and when the bearing plate becomes loose from the roof in the other. It also can be approximated for either method of testing by noting the load when the first abrupt change in the slope of the jack load-bolt displacement curve occurs. 3. The anchorage characteristics of the test bolt can be determined from the data obtained from either method by examining the slope of the jack load-bolt displacement curve above the point at which the true bolt load is equal to the jack load.

Jan 1, 1960

By M. M. Tilman

The Federal Bureau of Mines developed a rolling method that improves creep resistance and yield strengths of lead alloys containing up to 5 wt-pct Sb. The 0.69-inch-thick slab-cast alloys were breakdown-rolled to 0.226 inch and finish-rolled to 0.063 inch at 5-or 20-pct reduction per pass. Rolling was at room temperature to simulate conventional cold rolling, and at 75°, 125°, and 175° C. Two alternative methods evaluated consisted of (1) a single cold final pass followed by annealing and (2) a single hot final pass. Two additional processing methods involving percipitation strengthening were included for comparison. Compared with conventional cold rolling, hot rolling at 125° and 175° C with multiple light passes vastly improves creep resistance and raises yield strengths. Tensile strengths are less affected. The other treatments also improve creep resistance significantly and generally improve tensile properties; magnitudes vary with treatment and composition.

Jan 1, 1975

By Noel N. Moebs

Coal mine roof failure is categorized according to character, trend, or pattern of occurrence. Two principal categories of failure are proposed--geology related and stress related. Geology-related failure includes both lithology and structure. Each of several subcategories reflects the probable cause of failure and thereby provides a basis for the selection of appropriate techniques for reducing the incidence of failure. These control techniques, depending on local conditions, may include supplementary support, destressing, reduction of mine air humidity, or a change in the customary support methods.

Jan 1, 1986

The Mine Safety and Health Administration (MSHA) defines an independent contractor as "any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine." Contractors that perform specific types of work are required to report the number of employees who perform work at coal mines and at noncoal mines.

Jan 1, 2004

1. In 2002, a total of 7,125 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA). The largest percentage of all mining sectors1 was sand and gravel mines (49.1%). Sand and gravel mines are found throughout all 50 states.

Jan 1, 2004

1. In 2002, a total of 763 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include the mining of clay, trona, barite, phosphate rock, gypsum, talc, gemstones, and pumice. Nonmetal mines comprised 5.3% of all mining operations. • Nonmetal mining operations are located in all but nine states or territories (Alaska, Delaware, Maine, New Hampshire, Rhode Island, Vermont, Wisconsin, Puerto Rico, and the Virgin Islands). • Mines producing common clay comprised 29.2% (n = 223) of all nonmetal mining operations.

Jan 1, 2004