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By Roy F. Abernethy

All samples tested showed some loss of heating value for the 5-month period under all 4 storage conditions. The losses increased as the time of storage increased, with the pan-storage samples showing somewhat greater losses than those in cans. The individual daily analyses for the first 2 weeks and the analyses every other day for the third and fourth weeks of storage vary within the approximate tolerance of the test for heating value. During the first 2 months of storage the changes in heating values were not Significant for the samples from Pennsylvania, Indiana, and Colorado. The Ohio coal indicated some loss by the end of I month, which increased to a value measurable with certainty by the end of 2 months. These data show that (1) small changes may occur even to samples in closed cans and (2) the laboratory sample should be handled as expeditiously as is practical until the analysis is completed. The statement by the ASTM that "If the B.t.u. determination is an important consideration in the sale of coal, the time elapsed between sampling and analysis shall not exceed 30 days,"3/ is quite adequate for 3 of the 4 coals tested. The change in the Ohio coal stored for 30 days is merely indicated and could not be determined with certainty by the techniques normally employed. The data on free-swelling indexes determined on can samples, after 30° C. air drying, show that only the Indiana coal lost more than one unit in free-swelling index number in 120 days. No significant changes were observed with the samples from Pennsylvania, Ohio, and Colorado in the 5-month period.

Jan 1, 1958

By H. L. Riley

At the Southern Experiment Station, Tuscaloosa, Ala., reports are prepared from time to time on results of washability studies of coal from important beds in the Southern Appalachian region. The investigations that provide the material for these reports are made by the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama and the mine operators. The principal objective of a washability study is to obtain technically and commercially important data to aid in determining the best methods for preparing and utilizing the Nation's reserves, particularly of coking coals. Such information is also important from the standpoint of conservation, because it facilitates the selection of preparation methods that will yield an acceptable product with a minimum loss of coal to the rejects.

Jan 1, 1958

By John D. Bardill

Data from extensive tests was obtained on friction-head losses of various sand slurries, composed of materials of different specific gravities and under varying transport conditions, to provide useful information for designing hydraulic transport systems. The tests were run in a pilot plant through 2-, 3-, and 4-inch lines with slurries composed of relatively pure barite and limestone solids. Available grinding and classification equipment did not permit attaining a comparable size distribution in the two materials tested, thus preventing direct correlation of friction-head loss values to physical properties or mineral composition. A total of 495 measurements were made of limestone slurries in the 2-, 3-, and 4-inch pipe test sections at flow velocities from 6 to 14 feet per second and pulp densities from 40 to 70 percent solids. A total of 640 measurements of barite slurries were made in the 3-and 4-inch pipe test sections at flow velocities between 7 and 14 f.p.s. and pulp densities ranging from 40 to 80 percent solids.

Jan 1, 1962

By Wilton Johnson

Native asphalt was produced by three companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by one firm, R. L. White Co., Uvalde County, TX. Gilsonite, a solidified hydrocarbon found only in Colorado and Utah, was mined by two firms, American Gilsonite Co., a division of Chevron Resources Co. (a subsidiary of Standard Oil Co. of California), and Ziegler Chemical and Mineral Corp. Hydrocarbon Mining Co. (a subsidiary of Oberon Oil Inc., a Utah corporation) closed its mining operation during the year.

Jan 1, 1988

By Sean Gallagher

Humankind's interest in measurement of human physical strength probably dates to the first humans. At that time, life was truly a struggle in which the fittest survived. To a great extent, fittest meant strongest. Interestingly, current interest in human physical strength in the workplace stems from 1970-1980s vintage research demonstrating that persons with adequate physical strength are less likely to be injured on physically demanding jobs. Survival in many modem workplaces may still be a case of survival of the strongest. There is, however, a flip side to this issue - that persons with limited strength are more likely to be injured on "hard" jobs. To address this problem, we can apply what we know about physical strength to job design. "Hard" jobs can be redesigned to be within the physical strength capability of most people. Since physical strength is important to these jobs, we must find ways to quantify it through testing. This publication concerns human physical strength testing. Its purpose is not to recommend any particular type of testing, but rather to describe the types of testing available and their uses. It is up to each individual user of strength testing to decide which testing technique is most appropriate for his or her particular application. This booklet discusses four types of strength testing: isometric, isoinertial, psychophysical, and isokinetic.

Jan 1, 1998

By Allen McComas, Frank Chase, Phyllip Worley

Longwall mining has gained the reputation as being the safest extraction method in underground coal mines. However, one of the most difficult tasks associated with longwall mining is moving the face once a panel is completed. Based on Mine Safety and Health Administration (MSHA) fatality reports since 1996, longwall face recovery operations have claimed the lives of 5 U.S. miners and have resulted in numerous injuries. Recovery operations can be hazardous because they involve moving large pieces of equipment in very confined spaces. They are also conducted in highly stressed ground conditions due to front abutment loads generated by panel extraction. Shield removal is the most hazardous operation during face recovery because miners are constantly exposed to the unpredictable gob edge. To protect the miners, one or more walking shields, cribbing and/or other supplemental roof and standing supports are typically employed as breaker line supports as each shield is removed. At the Harris No. 1 Mine in southern WV, mobile roof supports (MRS’s) have been used in lieu of traditional walking shields on 17 face moves since 1997. MRS’s are shield-like support units mounted on crawler tracks and are commonly used during room-and-pillar retreat mining operations. For longwall recovery, the two biggest advantages that MRS’s have over traditional walking shields are that they are remotely controlled and are highly maneuverable. MRS’s have contributed to safer shield recovery and shorter move times at the Harris No. 1 Mine. This paper will address both the safety and the operational issues associated with MRS usage during shield recovery. It will also discuss new developments, including the use of the inherently safer battery powered MRS’s, which have been recently certified by the Mine Safety and Health Administration.

By K. E. Robinson

This study is the extension of an investigation of reclamation of floodplain areas in the Coeur d'Alene Mining District, Idaho, that are unuseable in their natural condition, by construction of landfills with mill tailings. The study develops a valley-wide tailings disposal plan to utilize 20 potential landfill sites on floodplain areas and presents measures for reclaiming the sites for subsequent productive use. Field and laboratory testing on a test section and two abandoned impoundments support the use of hydraulically deposited tailings for landfill construction. Hydrological testing has shown that controlled discharge from tailings impoundments results in contaminant levels in the discharge below regulated standards. Additional testing indicated that compacted soil liners and pond management provide adequate contaminant abatement where acid-generating tailings are encountered. Mechanical compaction, including surcharge loading, upgrades foundation support capacity so that construction on the surface of tailings deposits is feasible. On completion of the testing program, the test sections were abandoned and rehabilitated. Details concerning potential landfill sites have been refined. At recent production rates, the 20 sites would result in 680 acres of reclaimed land, while providing a minimum of 40 years of tailings storage capacity. A general design has been developed for the retention dikes. Aspects of embankment stability, including liquefaction are discussed, and are shown to provide an adequate factor of safety under the anticipated range of operating conditions.

Jan 1, 1983

By R. Q. Shotts

Factors of geological structure and occurrence of coalbeds, plus the resulting mining conditions, have required more care in preparing coals in Alabama than in most other districts almost since mining Alabama coals began. For this reason, literature on these coals may be interesting to those in areas where prime coals have been mined out, and thinner and less regular beds must now be exploited. This literature review has been arranged in order of subject matter. Some references have been listed more than once, but each separate review is limited to the material pertaining to the subject matter being discussed. For those seeking specific information, the authors have indicated which items repeat material and which items are most complete or specific. Geology, preparation, and carbonization of coal have been reviewed the most frequently.

Jan 1, 1963

By Richard Havens

Acidic and basic uranium leach plant residues located on the Navajo Indian Reservation, Tuba City, Ariz., were successfully stabilized against wind erosion using a relatively low-cost chemical method. An elastomeric polymer chemical was applied to the dike areas and a calcium magnesium lignosulfonate to the beach areas of three tailings ponds. The water-soluble chemicals were applied with an automated sprinkling system. The stabilization cost was $335 per acre for the 34.5-acre tract.

Jan 1, 1969

By D. H. Desy

The Bureau of Mines has conducted research on the ignition of methane-air mixtures by sparks caused by frictional impact of aluminum alloys on rusted steel at typical coal mine fan speeds. The objectives were to establish the incendivity of aluminum alloys under these conditions, to investigate differences between aluminum alloys, and to evaluate substitute materials for the aluminum-steel combination. With a specially designed apparatus, three commercial aluminum casting alloys and a number of experimental aluminum alloys were tested for incendivity of the frictional impact against rusted steel in flammable methane-air mixtures. All aluminum alloys tested produced some ignitions. Of the experimental alloys, the harder alloys and those containing silicon tended to be more incendive than the others. With the normal experimental conditions, constructional steel, stainless steel, brass, and plastic did not cause ignition of methane-air mixtures in frictional impact against rusted steel. Some ignitions occurred with constructional steel at high speed in more flammable gas mixtures enriched with oxygen. From these findings, it is suggested that constructional material combinations other than the aluminum-steel combustion would minimize this inc endive hazard. A detailed description is given of previous research, and comparison is made with present results where appropriate.

Jan 1, 1975

By Kray Luxbacher, Erik Westman, Peter Swanson

Three-dimensional time-lapse velocity tomograms were generated to image stress redistribution around a longwall panel to produce a better understanding of the mechanisms that lead to ground failure. Mining-induced microseismic events provided passive sources for the three-dimensional velocity tomography. Surface-mounted geophones monitored microseismic activity for 18 days. Most similar studies have utilized active sources including longwall shearers, controlled explosions, and hammer blows. These active sources generally require a person to initiate and measure the location and time of the source, and are not conducive to continuous monitoring. This method utilizes mining induced microseismic events as passive sources and lends itself well to continuous monitoring. Two event location methods were compared in order to move toward quantification of tomographic results in terms of ground conditions. Additionally, LAMODEL was utilized to determine the expected stress distribution around the longwall panel and compare these images to the velocity tomograms. Eighteen tomograms were generated, one per day, and high velocity regions in the set of tomograms generated from the initial location algorithm correlated with abutment stress redistribution predicted by numerical modeling. This research is significant as it has the potential to improve safety in underground mines and is the only example of long term passive velocity tomography implementation for the purpose of inferring stress redistribution around an area of active mining. Though still immature, this technology has the potential to allow mine personnel to image areas of active mining on a regular basis and detect areas with anomalous velocity distributions indicating potential safety hazards.

By R. Q. Shotts

Factors of geological structure and occurrence of coalbeds, plus the resulting mining conditions, have required more care in preparing coals in Alabama than in most other districts almost since mining Alabama coals began. For this reason, literature on these coals may be interesting to those in areas where prime coals have been mined out, and thinner and less regular beds must now be exploited. This literature review has been arranged in order of subject matter. Some references have been listed more than once, but each separate review is limited to the material pertaining to the subject matter being discussed. For those seeking specific information, the authors have indicated which items repeat material and which items are most complete or specific. Geology, preparation, and carbonization of coal have been reviewed the most frequently.

Jan 1, 1963

By P. J. Remington

Field measurements utilizing a seat pad accelerometer were made on 25 underground coal mining machines in order to quantify the vibration levels experienced by the operators. Those data were combined with information on the statistics of the operating times of those machines in order to compare the operator's vibration exposure to the criteria in ISO 2631, "A Guide for the Evaluation of Human Exposure to Whole Body vibration." The comparison showed that about 30% to 40" of all underground coal mining machine operators can be expected to be exposed to vibration exceeding the fatigue decreased proficiency criterion, whereas only 10 to 15% would be expected to experience vibration exceeding the exposure limit. The primary sources of the exposure are shuttle cars and possibly scoop trams. Detailed exposure statistics are presented and the implications of the results are discussed.

Jan 1, 1983

By George W. Huseman, W. D. Mcmillan

"INTRODUCTION Feldspars represent one of the most abundant groups of minerals and constitute nearly Go percent of the material contained in the igneous rocks. They are grouped in a series of related aluminum silicates with varying amounts of potash, soda, and lime. .Approximately 85 percent of the feldspar produced in the United States is used as a flux in the production of glass, pottery, enamel and sanitary ware, brick, and tile. Notwithstanding the abundance of feldspar in the earth's crust, the only deposits that are worked to any extent are the pegmatites or coarsely crystalline dikes where natural segregation of the constituents facilitates recovery of the feldspar with a minimum of free quartz, mica, tourmaline, garnet, and other iron-bearing minerals that are detrimental in most ceramic industries.Although there are three glassplants and numerous other ceramic industries in Texas, all of the feldspar used in these plants is from other States. In the Llano region of central Texas, however, there are numerous coarse pegmatite dikes consisting primarily of feldspar and quartz in ratios up to 3 to 1. One of the more important of these dikes is the Badu Hill deposit in Llano County, Tex., which was first described by Carl Chelf 4/ in 1942. Following an examination of the deposit by W. D. McMillan, engineer in charge of the Texas field office of the Bureau of Mines, in January 1946, a proposal was made to investigate the deposit by core drilling in cooperation with the Department of Ceramic Engineering, University of Texas. This report presents the results of the cooperative investigation, which was begun April 24, 1946, and completed May 17, 1946."

Jul 1, 1947

By Galen G. Waddell

The Deep Creek zinc and lead mine afforded an excellent example of a relatively small underground mine operation that approached the low mining costs of large, highly mechanized mines, An open stope mining method incorporating sublevel benches and vertical long holes was used (fig. 1). Detailed descriptions are given on the exploration program, stope development, stoping procedures, and pillar removal. Pressure grouting was used to check the inflow of water and thus prolong the life of the mine. Statistics on mining costs and on electric power consumption, haulage from mine to mill, and milling costs are included.

Jan 1, 1963

By Willard L. Hunter

The research described in this Bureau of Minus report was conducted to improve the chromium-iron ratio of offgrade chromite. Two methods were used: (1) Iron was selectively reduced from chromite by carbothermic reduction in an electric-arc furnace, and (2) a mixture of carbon, chromite, and sometimes fluorspar was chlorinated to remove a substantial part of the iron. Chromite concentrate from the Mouat deposit in Montana and from northern California was used in the test work. Chromium-bearing slag and chromite that had been beneficiated by a roast-leach process were each smelted to produce high-carbon ferrochromium. Iron was selectively reduced in a laboratory-scale., electric-arc furnace. Carbon additions to the smelting charges varied from 40 to 100 percent of the stoichiometric requirement, and slag basicities were varied from 0.4 to 1.0 chromium-iron ratios of more than 4:1 were obtained with 89 percent recovery of chromium in a chromium-bearing slag.

Jan 1, 1962

By R. S. Olsen

Although aluminum is easily leached from calcined clay with boiling mineral acids, the presence of fines and slimes in the leached residue has hindered the application of acid leaching processes. A feed preparation method was, therefore, devised that provided a dense, smooth-surfaced, fine-grained clay. The important factors affecting feed quality were determined to be (1) crushing the raw clay to the size desired for the leaching process, (2) moistening the crushed clay with a fine mist of water while tumbling on a rotating disk, (3) drying the misted clay, and (4) calcining the dried clay at 750° C in a fluidized bed. Clay treated by this method was leached with HCI, and its residue was washed by water displacement in 4-ft-deep beds. Bed permeabilities on the order of 47 darcys or 4.6 x 10-7 cm2 were obtained with the leached residues.

Jan 1, 1983

By David S. Yantek

Miners in underground coal mines experience prolonged exposure to high noise levels, often with A-weighted sound levels in excess of 90 dB. Field tests have shown that the continuous miner conveyor is a dominant noise source. This paper will identify the most significant noise-radiating surfaces on the continuous miner tail section using vibration levels and surface areas to estimate the sound power levels of each surface. In addition, using five test cases, this study will examine the effects of three engineering noise controls on the surface-averaged vibration levels and average sound levels measured with four microphones located two meters from the tail section. The noise-radiating surfaces of the conveyor’s tail section include the top and bottom decks, the sideboards, and the flex plates. Emphasis is placed on the changes in the estimated sound power levels in the 500 – 2500 Hz 1/3-octave bands since this frequency range accounts for 80-85% of the sound energy near the tail section. The results show that the bottom deck is the most significant noise radiator for the untreated miner. Installing a coated bottom deck reduces the estimated sound power level radiated from the bottom deck by 11 dB and the average sound level by 2 dB. Using a coated tail roller results in reductions of the estimated sound power levels for individual components from 1 to 4 dBand reduces the average sound level by 2 dB. Coating the slide plate has little effect on both the estimated radiated sound power levels and the average sound level. The test results indicate that modifications that reduce flex plate vibration and reduce energy transfer from the tail roller into the tail section will be effective in reducing noise when combined with a coated tail roller and coated return deck.

By David Schlain

The Bureau of Mines investigated methods for electrodepositing platinum-group metals from molten cyanide baths. The preparation of thick, protective coatings on molybdenum, Inconel, graphite, stainless steel, copper, and other structural metals were studied, as well as the electroforming of platinum and iridium crucibles. Iridium, rhodium, and ruthenium can be electrodeposited under an inert atmosphere, while platinum and palladium require the presence of air. Electrolytes may be prepared by direct-current electrolysis in NaCN or mixtures of NaCN and KCN using anodes of the particular platinum-group metal. When the concentration of metal increases to about 0.3 or 0.4 percent, the deposits become bright, adherent, and coherent. Current densities may be 10 to 25 ma/cm2, and plating rates are often 0.5 mil/hr. Platinum and palladium baths deteriorate because of the oxidation of cyanide to cyanate and carbonate, and the precipitation of metal. Changes in the platinum cyanide bath are relatively slow. The protection against oxidation afforded by the platinum-group metal coatings is evaluated by testing encapsulated specimens in a thermogravimetric balance. Surface pretreatment and the use of undercoats are discussed.

Jan 1, 1977

By C. A. Rhoades

The spillage that accumulates under conveyor belt lines presents a possible fire and explosion hazard fomiinqjetsoruiel, especially to those who must clean up the spillage. The U.S. Bureau of Mines conducted research to reduce this hazard by identifying and investigating the parameters affecting the efficiency of conveyor belt cleaning. The amount of material carried back under the conveyor and the wear rates of metal cleaning blades decreased with increasing blade-to-belt pressure to a limiting value, after which the carryback and wear rates remained essentially constant. The optimum blade-to-belt pressure was found to be 11 to 14 psi for the research conveyor system. Greater pressures increased the blade-belt friction without improving either cleaning or blade life. The modes of blade wear were three-body abrasion and slurry erosion caused by the sand-lime test mixture. Wear rates were reduced by increasing the metal hardness, opti-mizing the pressure, and removing conveyor belt imperfections. Corrosion was not observed to affect the wear of various steels in tests of less than 34 h. The results of this study should allow mine operators to run their conveyors under conditions that will maximize cleaning and minimize equipment wear.

Jan 1, 1989