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By John Nagy, Austin R. Cooper

Information is presented on the pressure and rate of pressure development during a dust explosion . The data were obtained in laboratory studies in a 75- cubic inch vessel with mineral , agricultural and chemical dusts . The factors investigated include dust concentration , oxygen concentration of the atmosphere , admixed inert powder , and admixed moisture . Information is given also on the effects of these factors on the composition of the atmosphere after the explosion .

Jan 1, 1964

By R. P. Maloney

The Bureau of Mines conducted a reconnaissance of the less accessible parts of the Beluga River coalfield in August 1957 to determine, if possible, which areas were most favorable for developing large reserves of coal suitable for open-pit mining. Several outcrops of subbituminous coal were observed within an area about 30 miles long and 3 miles wide; neither the length nor the width of the coal-bearing area was delineated by the examination. Coal beds 30 feet thick or more outcrop at two places, and beds 5 to 20 feet thick or more outcrop fairly abundantly along the Beluga River and its tributaries The coal measures appear to occur in a series of folds. The overburden comprises glacial gravels and poorly cemented sandstones and ranges from 20 to 400 feet in depth. Few partings were seen in any of the coal beds. Samples ranged in calorific value from 6,240 to 8,246 B. t. u. on an as-received basis. Adequate water is available for stripping by hydraulic methods.

Jan 1, 1958

By Noel N. Moebs

The coal wants at the Westland Mine in southwestern Pennsylvania consist chiefly of elongated, sandstone-filled channels with slickensided basal contacts. Tentatively identified as washouts, these channels are about 1,000 feet long and 300 feet wide, are erratic in occurrence and trend, and are difficult to delineate from the customary core drilling pattern. Roof conditions are hazardous adjacent to the washout contact, but roof stability is generally unaffected greater than 30 feet away.

Jan 1, 1981

By G. J. Slavens

The Bureau of Mines has devised technology to recover cobalt, nickel, and byproduct copper from domestic lateritic material using an oxidative, ammoniacal ammonium sulfate leach. Nickel, cobalt, and copper were recovered by solvent extraction and electrowinning. To reduce the cost and complexity of cobalt recovery, an alternate method using lig-nite to extract Co3+ was investigated as reported herein. In the first 25 BV (bed volumes) of solution contacted with lignite, 97 wt pct of the Co3+ was extracted in & downflow column at pH 9.3. After 85 BV, the lignite was loaded to 1.5 wt pct Co3+ and further ex-traction was minimal. The lignite extracted cobaltic ammine complexes rather than cobalt ions and was nonselective as to other -metal cations and ammonium ions. Deleterious cations and 80 wt pct of the nonammine ammonium ions were removed prior to acid elution of the lignite. The removal of the ammines prior to elution to produce an ammonium-ion-freeCo3+ eluate was only partially successful. Thus Co3+ removal from ammoniacal solutions by lignite is technically difficult and economically unfeasible. It was also determined that reduction of Co3+ to Co2+ occurred during the extraction-elution process.

Jan 1, 1984

By Albert E. Long

To date the commercial diamond bit setters have been principally interested in the speed with which they could produce a sharp, fast-cutting bit. Thus, a premium has been placed on setters who combine a high degree of manual dexterity with the ability quickly to select the Sharp points and edges of the diamonds and set them in the mold without lost motion. The premium on speed does not allow the setters the time, nor are they trained, to consider also the crystallographic structures of the diamonds which are the clues indicating the harder and more suitable working surfaces. Since early fall of 1949, the Bureau of Mines has been conducting a long-range series of experiments in which drill bort have been oriented in diamond bits in an effort to determine the effects and economic practicability of utilizing the hardest surfaces of the diamond crystal structure. The preliminary experiments completed to date indicate that a substantial saving in diamonds may be affected by using the harder areas of the diamonds as working surfaces in the crown of diamond bits. The experimental work is being conducted by the Bureau of Mines in the laboratories and full-scale mine of the Mining Research Branch, Minerals Technology Division, Region VIII, of the U. S. Bureau of Mines at the Mount Weather Station, Bluemont, Va.

Jan 1, 1951

By S. H. Lorain

This paper is one of a series on mining and milling method and costs being published by the United States Bureau of Mines. The Golden Messenger mine, operated by the United Gold Mines Corporation, is in the York-Confederate Gulch mining region in Luis and Clark County, Mont., 22 miles northeast of the city limits of Helena and about 1 mile north of the town of York. It is the first operation to exploit successfully the low-grade ores of the York-Confederate Gulch area. The unusual vein structure presents some mining problems that have been solved in ail interesting manner.

Jan 1, 1937

By John C. Gagliardi

The size and complexity of modern surface haulage trucks has resulted in an increased reliance upon sensors and electronic-based instrumentation for safe and efficient operation. Design engineers need accurate information about the equipment vibration environment to efficiently and effectively build components for installation on mobile mining equipment capable of withstanding the mine environment. Examples of such components include backup alarms, communication equipment, microprocessor-based controllers, and a wide variety of sensors. Unfortunately, this information is not available to the majority of both original equipment and aftermarket equipment manufacturers. To address this problem, the U.S. Bureau of Mines performed field vibration measurements on a variety of surface mining haulage trucks. The vibration measurements were then analyzed and test specifications were developed in the form of envelopes. In conjunction with test specifications, recommendations to aid manufacturers in implementing a vibration environment test program have been included with an illustrative example.

Jan 1, 2010

By Allan F. Smith

The Bureau of Mines studied toxic products produced by burning eight fire-resistant mines conveyor belts, a brattice cloth, and an electrical cable insulation obtained from laboratory-scale burning experiments under various air-flow conditions. Generally, CO product concentrations for most materials were noticeably higher then the NO2 and HC1 levels that were measured; also, no phosgene was detected. However, several of the fire-resistant belt samples yielded HC1 concentrations that were above the reported lethal level for 1/2 to 1-hour exposures, although these data were limited to flow conditions where air dilution effects were small; the belt materials that showed this behavior included samples of polyvinyl chloride, styrene butadiene, styrene butadiene blends, and a British neoprene which yielded the greatest amount of toxic vapor. In addition, some results are presented on the phosphoric acid concentrations that may be produced from the decomposition of ammonium dihydrogen phosphate when dispersed on a burning coalbed.

Jan 1, 1973

By Andrew B. Cecala

The U.S. Bureau of Mines has designed and tested a system called the Bag and Belt Cleaner Device (B&BCD) to reduce dust levels in and around the bag conveying and stacking process. The device physically cleans either 22.7 kg (50 lb) or 45.4 kg (100 lb) paper bags by using a combination of brushes and air jets. It is completely self-contained and is kept under negative pressure by a baghouse to ensure that dust and product removed from the bags during cleaning does not flow into the work environment and contaminate workers. The bags travel through the device on a chain conveyor, which permits any product or dust cleaned from the bags to fall into a hopper at the bottom of the device and be recycled back into the process via a screw conveyor. Once exiting the B&BCD, the outside of the bags and the conveyor are essentially product and dust free. The B&BCD was evaluated at two mineral processing plants to determine reductions with the device in use. The results of both field evaluations showed that the amount of product removed from the outside of the bags varied from 77 to 93 pet.

Jan 1, 2010

By Mark W. Ryan

The U.S. Bureau of Mines conducted a study to determine if commercially available automatic sprinklers could withstand the high static pressures in deep underground coal mines without leaking and if exposure to the mine environment affected their leak pressures. New sprinklers and sprinklers exposed to the mine environment were subjected to increasing pressures until leakage occurred. The average leak pressures of the new sprinklers ranged from 640 to 2,300 psig and were significantly different for sprinklers from different manufacturers and for different types of sprinklers. Generally, standard-response sprinklers withstood higher pressures than fast-response sprinklers. The results indicated that most commercially available sprinklers would withstand the high static pressures in deep underground coal mines; however, they would not provide the same reliability and safety factor as sprinklers used aboveground at or below their rated pressure of 175 psig. The average leak pressures of the sprinklers exposed to the mine environment ranged from 740 to 1,180 psig. The mine environment affected the ability of 66% of the sprinklers to withstand high static pressures. New sprinklers were also evaluated at pressures of at least 500 psig for 30 days to determine their ability to withstand long-term exposure to high static pressures; no leakage was observed.

Jan 1, 2010

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

Coalbeds exhibit a directional permeability, with the maximum permeability oriented parallel to the face cleat. Thus, the most efficient pattern of vertical degasification holes for a coalbed is dependent upon cleat orientation. Surface joints, infrared photolinears, and Ronchi grating photolinears were investigated as potential estimators of subsurface cleat orientation. Cleat orientations were masured in 18 mines, in the Pittsburgh coalbed in southwestern Pennsylvania and northern West Virginia to be used as a standard against which prediction techniques would be evaluated. Two cleat systems with a strong geographic segregation were measured in the study area: N 67° W - N 28° E (95° separation) for the north, and N 76° W - N 17° E (93° separation) for the south. Directional data obtained from the three techniques investigated yielded satisfactory regional predictions of cleat orientation. Analysis of surface joints was the only technique considered sufficiently reliable on a local basis. Prediction of cleat orientation is based on the pairing of the principal directional sets into all reasonable combinations of fundamental systems. The system or systems composed of the most dominant sets nearest to 90° separation are likely to be a reliable prediction of cleat orientation. The most dominant set of the system selected is likely to be the face cleat.

Jan 1, 1976

By John R. Bartels

In laboratory testing, the Bureau of Mines established criteria by which common resin-grouted roof bolting systems can be evaluated and compared. Ultimate strength and stiffness were determined for nonten-sioned full-column, point-anchor, tensioned full-column, and debondable resin-grouted bolts, and for variations on full-column boltsn Bolt per-formances were compared using the performance of the 3/4-in full-column resin-grouted bolt as the standard. New and innovative systems can also be qualitatively compared against this standard. Since the medium into which a resin-grouted bolt is installed is one of the most important parameters affecting bolt performance, various host mediums were used in the testing: sandstone, concrete, simulated coal, simulated shale, and plaster. Bolt performances expected in other mediums can be inferred from the response patterns obtained in these mediums. Results indicate several functional differences among bolt types. Where resistance to shear is important, point-anchor bolts may outperform nontensioned full-column bolts at a lower cost. In medium-to soft-strength rock, tensioned full-column bolts perform best. Also, varying the resin-steel ratio seems to have little effect on the properties of a full-column bolt, when proper resin mixing is ensured.

Jan 1, 1985

By H. A. Schrecengost, H. R. Gil, Alfred Clarkson, E. H. McCleary

Much has been written and many discussions have been held concerning the prevention of accidents in coal mines , and considerable progress has been made in eliminating hazards to the health and safety of underground workmen . Although much progress has been made in the reduction of injury rates in the Pennsylvania anthracite field , the injury rates for the anthracite mines of Pennsylvania are generally higher than the average for coal mines in the United States as a whole , because the mining conditions , including the safety problems , in the Pennsylvania anthracite fields are more complex than in other coal fields of the United States . Several factors contribute to this extremely difficult problem , among which are : Multiple - vein mining , steeply pitching measures , folds or faults , hard smooth floors underneath the veins , and the remining or reclaiming of pillars in severely crushed , broken ground . In the early days of the Pennsylvania anthracite industry , only the more productive veins were mined , and this resulted in bypassing those veins that were relatively thin and those containing considerable proportions of impurities . However , the development of modern coal - preparation equipment , improved marketing conditions , and the adoption of mechanical equipment , such as the various types of conveyors and scraper loaders , have made possible the recovery of the thinner and poorer veins . Furthermore , in the early days , little or no attempt was made to recover the coal pillars , usually owing to the great amount of virgin coal available . Consequently , much of the anthracite produced within the last few years has been recovered by second and third mining and frequently by fourth mining - in areas where operations had been suspended for many years . In such areas , the coal veins and intervening strata are usually crushed as the result of gradual subsidence , which intensifies the hazards incidental to roof control , haulage , ventilation , and mine gases . Moreover , the use of coal - cutting equipment is not practicable in most anthracite mines because of. the inclination of the veins and because , in crushed -ground areas , the faces must be advanced slowly and for short distances at a time to permit the erection of timber sets and the placing of forepoles to support the roof and sides . Thus , the slow process of mining brought about by these conditions has resulted in the production of only 0.424 ton of anthracite for each man- hour worked , as compared with 0.753 ton? for each man - hour worked at other coal mines in the United States . A summary contained in Bulletin 462,8/ a publication of the Federal Bureau of Mines , reveals that the rate of fatal injuries in the Pennsylvania anthracite industry was improved from 13.47 deaths per million tons produced in 1870 to 3.88 deaths per million tons mined in 1942. During the period March 16 , 1942 to January 1 , 1947 , the fatality rate was reduced from 3.88 to 2.87 deaths for each million tons mined . On the million man-hour basis , the rate of fatal injuries was reduced from 1.643 to 1.130 and the nonfatalinjury rate was lowered from 119.01 to 83.12 during the same period . The improvements made in both the fatal- and nonfatal - injury rates have required the cooperation of the workmen , the mining companies , and the State and Federal inspection departments . Many individual mines and companies have achieved commendable safety records which contributed greatly to the over - all average for the industry , particularly during the 1942-47 period . One of the most outstanding of these is the Continental mine of the Continental -Archbald Coal Co. , a member of the Moffat Co. Interests .

Jun 1, 1948

By Walter R. Storms

This paper, which describes the mining methods of the Potash Co. of America in Eddy County, N. Mex., is one of a series being prepared by the Mining Branch, of the Bureau of Mines on mining practices and methods in various mining districts of the United States. 4, T. The mine and plant of Potash Co. of America are situated in sec. 20 S., R.. 30, E.,. N. M. P. M., about 22 miles by paved road northeast of Carlsbad (fig. 1). A spur line of the Atchison, Topeka & Santa Fe Railroad also connects the mine with Carlsbad.

Apr 1, 1948

By Jr. Allan

"Although the advantages of large-capacity air receivers for underground mines are plainly evident from published information about various installations in the United States and abroad, details of their construction are not generally known in this country., Ordinary present-day air-compressor installations servicing mining machines are designed to supply air at a specified pressure in sufficient quantity to meet the peak demand of the mine,2/ although this demand may exist for only a few minutes out of 24 hours and, as usually happens, eventually exceeds the capacity of the compressor. Most of the receivers provided with these compressors (to a certain degree of standardi¬zation) are capable of storing a volume of air approximately equal to that compressed in 1 minute by the machine.3, 4/ As a result, during peak-load periods the compressor operates at full load capacity without maintaining kick-off pressure. At other periods of the work cycle, production of compressed air is intermittent.At least one large mine5/ has adopted large-capacity receivers to reduce wear on its air-compressing system caused by the sudden demand of peak loads. Under the old system, the compressors jumped suddenly from half speed to full speed; boilers furnishing steam to the compressors were taxed heavily to provide the increased requirements of power; and machines using the air, among which were four large hoists, were required to operate at 65 pounds per square inch rather than at the 90 pounds per square inch for which the compressors were regulated. Operation of air machines, especially drills, at pressures lower than those for which they were designed decreases their efficiency and increases maintenance costs. In addition, air that comes directly from the compressors has had little opportunity to cool and dry enroute.6./ As a result, quantities of compressor lubricant and water are carried into the machines that use the air. When expansion occurs in the cylinder or turbine of such engines, the temperature of the air drops, and this oil and water is precipitated. The water washes away lubricating oils in the machine, causing poor performance and high cost of maintenance; the compressor oil, in addition to being a poor lubricant for compresed-air engines, exerts a corrosive action on gaskets and rubber hoses.7/Reduction of peak demands on air compressors by large receivers lowers power costs by establishing more nearly constant load factors,8/ and in some cases by permitting the use of smaller compressor capacity.8,9/Load factor is the ratio of average demand to maximum demand; a low load factor costs money.10/Elimination of high-peak demands raises the load factor by making the average and the maximum demand more nearly equal. Further savings may be made possible by large receivers where their use permits charging to be done at night in regions having lower power rates during that period.11/Where ordinary receivers are used, compressor breakdowns cause immediate work stoppages in the mine owing to lack of air. Similarly, the capacity of a large receiver has been known to permit uninterrupted work in the mine until the compressors have been returned to service.9/Large-capacity receivers, either steel-tank or underground rock-chamber, offer a practical solution of many existing problems by providing a sufficient reserve of compressed air within the pressure range required for efficient operation of machines to level off peak demands on the compressor. The com¬pressors operate when the demand has reduced the pressure in the receiver below the regulating pressure and until all air used from the receiver has been replaced. It has been found possible in at least two mines,8.9/ one of which the author has visited, to entirely eliminate one compressor and to obtain more efficient performance from the remaining one by the construction of an underground coal-chamber receiver.8/"

Jan 1, 1950

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the thirteenth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The description of the deposits developed is followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The tactual data obtained during the project are reported in a series of Reports of Investigations beginning with No. 4251, of which this is the twelfth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate halt-township map. The description of each half township is followed by a description of each deposit developed in that halt township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski County, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigations beginning with No. 4251, of which this is the eighth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is no followed by a description of each deposit developed in that half township. The 14 half township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project, except the deep holes drilled to test the geophysical anomalies. The locations at those holes show on figure 13 in volume I. The descriptions of the deposits developed are followed by complete detailed logs at the drill holes. Many at the widely spaced exploratory holes did not discover bauxite of minable thickness and gra.de. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each halt township is given with the discussion covering that area.

Jan 1, 1948

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigations beginning with No. 4251, of which this is the third. The data are accompanied by maps showing the location of holes drilled and deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township-map. The description of each half township is followed by a description of each deposit developed in that half township.

Jan 1, 1948

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations No. 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the fifth. The data are accompanied by maps showing the location of holes drilled and deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in Volume I. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion of that area.

Jan 1, 1948