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By R. J. Matetic

The Bureau of Mines, as part of a program to improve mine planning and development, is currently investigating the effects of pillar load transfer, which can impact mining operations within a multiple-seam configuration. A comparative study was performed at two separate mine sites. The objective of this study was to compare two mines, each affected by this pillar load transfer mechanism, and to show how this interaction affected underground workings by the installing and monitoring underground instrumentation. At mine site A where the overburden was 1,000 ft, the innerburden thickness was less than a pillar width (40 to 45 ft), overlays of the mine layout show pillars were not superpositioned, excessive roof to floor convergence was measured, and pressure readings indicated pillar core loading only. At mine site B, the overburden was approximately 555 ft, the innerburden thickness was approximately 105 ft, overlays of the mine layout show pillars were superpositioned, minimal roof to floor convergence was measured, and pressure readings indicated a skin loading only.

Jan 1, 1988

By Danny Hagood

The drilling of horizontal boreholes as a means of degasification in advance of mining has been tried at Jim Walter Resources, Inc., No. 4 Mine. In a joint venture with the U.S. Bureau of Mines, a series of horizontal drainage boreholes have been drilled in the panels of an advancing continuous miner section with impressive results. The combined methane gas production rate has ranged from 205,000 to 680,000 cfd (cubic feet per day} with individual "in-seam" horizontal holes producing up to 332,000 cfd. The methane liberation from the ribs for the entire panel length has decreased from an average of 8.75 cfm (cubic feet per minute) per 100 feet of entry to 4.05 cfm per 100 feet, a 54 per cent reduction. The actual gas concentration as measure at the surface discharge point normally ranges from 85 per cent to 95 per cent methane. As a consequence of the significant reduction in methane liberation rates from the panels of the section, a 50 per cent increase in productivity from the section has been realized.

Jan 1, 1983

By G. M. Potter, S. J. Hussey, R. Havens

The Artillery Peak manganese ores , from one of the largest known manganese deposits in the United States , present a difficult problem in concentration because they are low-grade and the association of manganese and gangue minerals is intimate and complex. The known size of this deposit has justified investigation of processes such as leaching, wherein preliminary enrichment of the original feed might be advantageous .. Therefore , the ore-dressing studies on Artillery Peak ores were carried on with the object not only of making directly marketable manganese products but also of removing acid-consuming calcite and raising the grade of ore for leachingplant feed . Owing to the extent of the deposits , test work was carried on at the Salt Lake laboratories in considerable detail on several lots of ore of varying composition . This paper summarizes the results obtained from laboratory testing of four samples obtained by engineers of the Mining Branch from the Maggie Canyon area of the Artillery Peak deposit . Also included are results obtained from testing one sample of Chapin Group ore , which was considered representative of numerous very low-grade ores submitted from the Artillery Peak district . During the course of the investigations , many data were obtained and compiled , but for the sake of brevity , data of secondary importance have been omitted or condensed and only those tests giving the more pertinent results are discussed in detail ...

Nov 1, 1947

By J. B. Zadra, J. M. Gomes, Don H. Baker

Electrolytic deposition at 1,000 ° C in an electrolyte essentially consisting of 7 parts sodium pyrophosphate , 2 parts sodium chloride , and 1 part sodium tetraborate yielded tungsten of 99.9 percent purity . Scheelite concentrates containing 25 to 73 percent WO, and varying quantities of iron , lime , and silica were used as feed materials for the electrolysis . The metal contained less than 0.01 weight - percent each of iron , calcium , silicon , aluminum , carbon , and oxygen . Modification of the electrolyte permitted deposition of equal - quality metal from scheelite concentrates containing higher quantities of iron , calcium , and silica . The electrolytic separation of molybdenum and tungsten was accomplished by minor variations in the operating procedures .

Jan 1, 1964

By T. M. Barczak

One of the primary goals of Bureau of Mines research is to reduce the cost of coal mining by improving the efficiency of longwall supports. One method of achieving this goal is the optimization of stress distribution within the support structure, resulting in a lower overall weight, more fully stressed shield. However, before stress optimization can be initiated, load conditions must be defined that cause maximum stress in the various support components. A finite-element model of a longwall shield was used to identify these critical load conditions. These load conditions were then evaluated in the Bureau's mine roof simulator (MRS) by instrumentation of a longwall shield and measurement of strains in each of the shield components. The critical (canopy-base contact) load conditions were identified that can cause structural failure at less than rated shield (hydraulic yield) capacity. Comparisons were made between full-contact and partial-contact load conditions. Other parameters investigated included the stiffness of the contact material, changes in shield geometry, rate of load application, and effects of horizontal constraint. Conclusions were drawn regarding the structural integrity of the major shield components and potential for stress optimization.

Jan 1, 1987

By Laxman S. Sundae

Laboratory tests were conducted at the U.S. Bureau of Mines to determine the effects of roof-bolt drilling parameters on penetration rate in sandstone using tungsten carbide alloy (WC-Co) and polycrystalline diamond compact (PDC) drill bits. During the tests, water pressure of 552 kPa was found to be adequate for removing the cuttings from the tops of drill holes. Test results show that for both types of bits, penetration rate increased when thrust was raised from 227 to 1,588 kg. When water pressure rose from 554± 120 to 1,344±350 kPa, the effect on penetration rate was not significantly different. Conventional WC-Co bits became dull when one or two holes were drilled, after which the penetration rate dropped dramatically. Microscopic examination shows that the cutting edges of PDC bits also become somewhat dull, but at a much lesser rate than WC-Co tips. Microscopic examination also reveals that the wear mechanism of WC-Co and PDC bits is quite different, which may explain the longer life of the PDC bits.

Jan 1, 2010

By Edward D. Thimons

A remote-actuated stench gas fire-warning system has been designed and tested by the Bureau of Mines. This system makes use of the hard-wire network for the mine's phone pager system, thus greatly reducing the system cost. By locating stench gas canisters with remote-actuation release capabilities near working sections, the fire-warning time can be greatly reduced. In a test of the system in a Missouri lead mine, the time required to warn miners of a fire at two working faces was reduced from about 20min with the conventional system to less than 4 min with the remote-actuated system.

Jan 1, 1984

By Paul T. Allsman

This paper describes metal- mining practices at the Harrington -Hickory lead - silver - zinc mine at Milford , Beaver County , Utah . The operations of the Harrington-Hickory incorporate a number of features that should prove of interest and value to other operators of small mines . These features include employee participation in profits , a well- laid -out electrical system, adequate financing , a well - balanced equipment and supply inventory , a well - organized system of bookkeeping , adequate roads , and good management . As crude ore is shipped directly to smelters and mills in the Salt Lake Valley , close attention is paid to see that the ore is segregated by classes and treated where it can bring the greatest not return . A combination of these features has resulted in maintaining relatively low costs, considering the grade and size of ore shoots at a time , during and following the war , when equipment , supplies , and labor were costly and difficult to obtain . The period covered in this report includes two war years and two years following , from April 1, 1944 to June 30 , 1947 .

Apr 1, 1949

By H. R. Appell

The Bureau of Mines studied the conversion of a variety of cellulosic wastes, for example, sawdust, bovine manure, sewage sludge, urban refuse (free of metal and ceramics), etc., to heavy oils. The objective of the investigation was to determine the scope of the reaction and elucidate the chemistry involved. The reactions took place in the presence of synthesis gas and water or carbon monoxide and water under conditions of elevated temperatures and pressures. Waste conversions above 90 pct, often near 99 pct, with oil yields in the range of 40 to 60 pct, were obtained in the temperature range of 250° to 425° C and pressure range of 1,500 to 4,000 psig. Because mild conditions were sought, most of the experiments were conducted at temperatures of 250° to 350° C and pressures of 1,500 to 3,000 psig. In general, lower viscosity products were obtained at higher reaction temperatures. Conversions and oil yields were significantly increased by operating in the presence of a high-boiling oil; either anthracene oil or oil recycled from the process was satisfactory. Synthesis gas containing 50 pct carbon monoxide gave satisfactory results as a replacement for carbon monoxide. Cobalt molybdate on alumina catalyst, used with sodium carbonate, gave a product of lower viscosity and lower oxygen content than sodium carbonate used as the sole catalyst. The waste-to-oil process has been successfully investigated in continuous flow equipment as well as in batch autoclaves.

Jan 1, 1975

By Thomas E. Green

A combined solvent extract ion-spectrophotometric method for the determination of as little as 1 ppm of copper in tungsten metal or tungstic oxide has been developed and evaluated. Metallic samples are converted to tungstic oxide by treatment with hydrofluoric and nitric acids. The oxide is then dissolved in sodium hydroxide, and the copper is extracted as the colored neocuproine complex. Total elapsed time for the analysis is approximately 1-1/2 days; however, actual working time for a group of six or eight determinations is less than 4 hours. Precision at the 2-ppm level is better than 0.1 ppm.

Jan 1, 1963

By Michael S. Wieland

The work-principle from thermodynamics was used to formulate a model for predicting toxic fumes from mining explosives in underground chamber tests, where rapid turbulent combustion within the surrounding air noticeably changes the resulting concentrations. Two model constants were required to help characterize the reaction zone undergoing rapid chemical transformations in conjunction with heat transfer and work output: a stoichiometry mixing fraction and a reaction-quenching temperature. Rudimentary theory with an unsteady uniform concentration gradient was taken to characterize the combustion zone, yielding 75% for the mixing fraction. Four quenching temperature trends were resolved and compared to test results of ammonium nitrate compositions with different fuel-oil percentages (ANFO). The quenching temperature 2345 K was the optimum choice for fitting the two major components of fume toxicity: carbon monoxide (CO) and total nitrogen oxides (NOx). The resulting two-constant model was used to generate comparisons for test results of ANFO compositions with additives. Though respectable fits were usually found, charge formulations which reacted weakly could not be resolved numerically. The work-principle model yields toxic concentrations for a range of charge formulations, making it a useful tool for investigating the potential hazard of released fumes and reducing the risk of unwanted incidents. Keywords: Toxicity; Fumes; Explosives

By EINAR M. ARENTZEN

This information circular. deais primarily with an engineering descrip- tion of a type of longwall cutting and loading machine developed by Eick- hoff Maschinenfabrik, Bochum, Germany..: This machine is supposed to have been developed and tested during the latter part of 1941 and early 1942. The only source of information is con- tained in certain literature and engineering data, with drawings which were acquired by the Allied Military Authorities when Germany was occupied; and the information will have to be limited because the writer has not seen the machine in the factory or in operation. However, the information may be of interest to the coal-mining industry in this country, and for this reason our Government has decided to publish the data procured so far. The Eickhoff cutting and loading machine is particularly suitable for the longwall mining system. It can only be used under that type of mining system and is not suitable for the more common type known in this country as room-and-pillar work. The material for the description of the machine and its operation was compiled and translated from German drawings and operating instructions. These detailed drawings and instructions are on file with the Bureau of Mines and are available for inspection by any responsible person interested in the details of the construction of the machine.

Dec 1, 1946

By John C. Feeley

This paper is the result of a field study of prospect drilling in the Florida phosphate fields. The objective is to describe the drilling methods employed . . Since the general policies of the operating companies in the land - pebble area do not permit the dissemination of prospecting information and costs thereof , the writer has carefully avoided mentioning names and locations except by reference to existing publications ,

May 1, 1949

By B. B. Letson

The heats of formation of lithium chloride and lithium oxalate were determined with the aid of a Bureau-developed, glass Dewar-type solution calorimeter which uses thermistors as its temperature sensing element. Values obtained at 298.15° K were -98.38 ± 0.54 kcal/mole for lithium chloride and -329.02 ± 0.79 kcal/mole for lithium oxalate, using graphite as the standard state for carbon.

Jan 1, 1965

By David E. Emerson

An improved method and apparatus for determining the impurities in helium by preconcentration and subsequent analysis by mass spectrometry are described. Preconcentration of the impurities is accomplished by passing a known volume of helium, at slightly above atmospheric pressure, through a metal coil and trap assembly immersed in liquid helium. The concentrated impurities are then analyzed by mass spectrometry. This method can detect impurities in the range of 0.01 to 600 ppm with an accuracy of better than ±0.05 ppm at the 1-ppm level. One operator can analyze 15 samples in an 8-hour day.

Jan 1, 1970

By P. W. Jeran, C. D. Sullivan, C. M. McCulloch

A series of geological surveys were completed in six coal mines in connection with a Bureau of Mines research program on methane control. The aim of these surveys was twofold: First, to study the overall geology of the coalbed, and second to use the resulting data to evaluate the influence of the geological characteristics of the coalbed on safe and efficient coal extraction. This report explains the advantages of geologic maps and fence diagrams in coal mining, and how the knowledge gained from such geologic investigations of mines can help control many underground problems.

Jan 1, 1975

By Sumner M. Anderson

ATHOUGH scattered signs of increased activity in the mining industry accompanied an incipient improvement in the overall economic situation during the latter months of 1963, production levels for the year as a whole responded to the general 1962-63 business recession with a 4.2 percent decline. The petroleum industry, active since 1907, did not become a dynamic force in the economy until exploration and drilling contracts were concluded with private companies in 1958 and 1959; on November 15, 1963, having virtually achieved self-sufficiency in petroleum in the preceding year, those contracts were unilaterally annulled. In the field of metallics, the only approach to internal sufficiency-aside from the iron and steel industry that has depended heavily on the importing of basic raw materials-has been in mining, smelting, and refining lead and zinc although iron ore, silver, beryllium, tantalite, and tungsten have been mine production items of economic significance. Reserves of lead, zinc, silver, bismuth, vanadium, and low-grade and metallurgically difficult iron ore-as well as those of beryllium, tantalite, and tungsten which are produced primarily for export-appear to be fairly abundant. The exploration of deposits of copper, cobalt, tin, lithium, gold, manganese and uranium has been undertaken on a relatively small scale, and little precise information is available on the extent of reserves. Argentina is dependent on foreign sources for part of its required iron and steel and, except for lead and zinc, most of its nonferrous metals. Nonmetallies and solid fuels present an exceptionally varied array of production items among which cement had the second largest 1963 output in South America. Borates, bentonite, common clay, diatomite, fluorite, granite, lime, limestone, obsidian, onyx, rhodochrosite, salt, and spodumene ordinarily are produced for export either exclusively or in excess of domestic consumption requirements. Barite, cement, chalk, gypsum, marble, and mica are both exported and imported. Argentina depends entirely or partly on imports for coal and coke, certain special types of clay, mineral abrasives, graphite, magnesite, mineral fertilizers, sulfur, talc, and minerals for construction, the last group being chiefly attributable to convenience of river transport from Uruguay.

Jan 1, 1964

By A. W. Khair, L. D. Gehl

"This paper describes the study of bit wear characteristics on three types of rock namely Tennessee sandstone, Berea sandstone and Indiana limestone. High content of quartz with quartz cement in Tennessee sandstone causes removal of material from the bit body and dam2ge to the tip of the bit resulting into excessive weight and height loss as compared to other two types of rock. The drum speed and water spray pressure do not contribute significant effect on bit wear. The polycrystalline compact diamond (PCD) tipped bits are more wear resistant than the ordinary tungsten carbide (WC) tipped bits, but, due to wider body of PCD bits, the wear rate increases particularly at greater depth of cut. INTRODUCTIONThe impact of bit-rock interaction during the cutting process in underground coal mines has always attracted the-interests of mining operators, researchers and the manufacturers. Coal cutting bears directly on airborne coal dust generation which causes ""black lung"" in coal workers. On the other hand, rock cutting generates frictional sparks causing face ignitions. The bit wear not only produces airborne rcspirable coal dust , but also affects the productivity, safety and economy. Hun and Evans (J) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits. The results of a study (2) suggested that after 7% of weight loss, the bit should be replaced. In a survey study (3), it was found that the bit consumption of bit had an effect on the productivity and utilization of the continuous miners. The mining industry is yet to receive a solution which could provide them with optimum operating parameters for coal cutting machines in underground C9al mines.The study was, therefore, taken up to determine wear characteristics as influenced by the rock propenies and varying operating parameters. For the purpose of this study, three types of rock, Tennessee sandstone, Berea sandstone and Indiana limestone were used. The machine operating parameters included (i) drum speed, (ii) water spray pressure and (iii) bit type. Besides studying the wear characteristics, the effects of these parameters on the required cutting force, specific energy consumption, acoustic emission generation and bit temperature rise were also studied. Also, the preliminary experiments were performed to compare the bit wear between PCD and WC tipped bits."

Dec 1, 1995

By J. L. Stauffer, L. J. Gaydos, L. M. Demers, D. C. Kuhn

"Eicosanoids and cytokines produced by alveolar macrophages (AM) are key mediators of pulmonary inflammation and fibrosis. In order to determine if eicosanoid production and cytokine production are altered in AM obtained from coal miners, we compared production of prostaglandin E2 (PCE2), thromboxane A2 (TXA2), leukotriene B4 (LTB4), interleukin-1 beta (IL-1B ), and tumor necrosis factor alpha (TNfa.) by cultured AM from normal human subjects and coal miners. The recovery of AM from miners' lungs by bronchoalveolar lavage was significantly greater than that from control subjects. Mean eicosanoid and cytokine production by AM from active miners was also increased compared to AM from control subjects, but this increase was not statistically significant. AM from control subjects produced significantly more TXA2 and TNFa. when exposed to lipopolysaccharide than did AM from miners. The cyclooxygenase inhibitor suprofen reduced PGE1 and TXA1 production and TNF0t. release but had no effect on LTB4 production or IL-1B release by miners' AM. The lipoxygenase inhibitor nordihydroguaiaretic acid attenuated TNFa release, as well as that of LTB4, but had no effect on IL-1B release. Inhibition of thromboxane synthase by UK 38,485 also reduced TNFa release by active miners ' AM but had no effect on PGE1, LTB, production, or IL-1 f3 release. The results of these studies suggest that occupational inhalation of coal dust may increase total lung eicosanoid and cytokine levels and reduce the reactivity of AM to bacterial endotoxin. Furthermore, coal dust-induced changes in both eicosanoid and cytokine release may be subject to pharmacological modulation.The alveolar macrophage (AM) is a primary defensive cell in the lung and is one of the first cell types to encounter inhaled mineral dust. The response of the AM to invading foreign material is designed to enhance the defensive capacity of the lung. However, in the case of occupational inhalation of mineral dust particles, this response may be inappropriate, resulting not in the defense of the lung but in chronic inflammation and fibrosis (Rom et al., 1987; Takemura et al., 1989). The reaction of the AM to chronic mineral dust exposure may involve the exaggerated release of paracrine mediators of lung function, including eicosanoids (oxygenated derivatives of arachidonic acid) and peptides, including cytokines and growth factors (Sibille & Reynolds, 1990). Eicosanoids are involved in bronchial and vascular smooth muscle reactivity, vascular permeability, fibroblast growth, and the recruitment of additional immune cells to the alveolar space (Barnard et al., 1992; Elias et al., 1985; Scott et al., 1982). AM-derived cytokines such as interleukin-1 beta (IL-1 B) and tumor necrosis factor alpha (TN Fa) have a variety of biological activities including the regulation of fibroblast growth and proliferation (Becker et al., 1989; Libby et al., 1989; Schmidt et al., 1984). Interestingly, in vitro studies with macrophages suggest that the production of cytokines may be linked to eicosanoid production, in particular that prostaglandin E2 (PGE2) may down-regulate IL-1 f3 and TN Foe production by the AM (Bonta et al., 1989; Kunkel et al., 1986; Monick et al., 1987)."

Dec 1, 1996

By S. L. Windes

For a number of years, the Bureau of Mines conducted tests on various types of structures to determine the effect of seismic vibrations emanating from quarry blasting in an effort to determine an index of damage . Associated with these tests , occasional records were made of the characteristics of. the air blast or concussion from the explosions . Although the importance of the air - blast problem was recognized , the equipment was not designed for air -blast measurements , nor was the early research program concerned with the problem . After the ground - vibration tests had been completed , attention was turned to study of the air blast and its effect . The air - blast problem in reference to quarry and mine blasting may be divided conveniently into three phases : (1 ) Determination of the fundamental characteristics of the air blast , such as the pressure - time relationship , speed of propagation, attenuation , and the like ; ( 2) effect of blasting conditions on these air -blast characteristics ; and ( 3) determination of the conditions necessary for damage to structures . The initial step was the development of microphones suitable for recording the anticipated blast pressures. Such microphones were designed and built during 1940 , and described in technical detail for publication ( 2)3/. Briefly, the microphone adopted was a small, plate - diaphragm condenser type . The recording was through special transducer amplifiers with low -frequency response to zero cycles per second and a Duddell - type oscillograph of special design .

Feb 1, 1942