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By John T. Kuo

The miner's seismic source strength can be approximately estimated on the basis of a single force acting in an infinite medium. Because of the uncertain- ty involved in estimating the amount of conversion from mechanical energy to seismic energy, the source strength thus estimated may be in error by as much as a half-order of magnitude. Calculations of wave transmission must take into account geometrical spreading, dissipation of energy by internal friction, and energy partition due to reflection and refraction of waves impinging on inter- faces in the layered earth. Theoretically derived peak-to-peak particle velocities in microinches per second (PIPS) are given for two models ; viz: (i) 50-feet thick and (ii) 100- feet thick 4000 ft/sec layers with Q = 20, overlying a half-space of 10,000 ft/sec material with Q = 5O;for the cases .of a hammer blow and a timber impact, at the frequencies of 50 Hz and 100 Hz. Comparison of the theoretically derived peak-to-peak particle velocity with experimental data taken at the Copper Queen Mine indicates that the theoretical particle velocity may be overestimated. A discussion of the distortion of seismic wavefronts by mine tunnels indicates that it is unfavorable to use a seismic source impact on the floor of the tunnel, since deceptive delays in arrival time are liable to occur at the surface. A program of parallel theoretical and experimental work is required to clarify uncertainties still associated with the nature and strength of the miner's seismic source signal which cannot be resolved within the approximations of this work. Its major components include theoretical investigations of the (1) Wave diffraction and scattering of an impact source on a face of a cylindrical cavity. (2) Impact of an elastic object on an elastic medium.

Jan 1, 1974

Roof screening for ground control originated with metal miners in the western United States. At first chain-link fence was used, but because it was so difficult to handle, the miners started installing a more rigid welded wire screen used in the concrete industry. Eventually coal mines in the west began to use screen, and now more and more coal operations, especially longwall mines, are installing roof screen on a regular basis. Screen use has recently increased in the Illinois basin and is now making its way to underground coal mines in the eastern U.S.

By James W. Ballard

The facts are generally accepted that an atmosphere containing large quantities of any dust is objectionable to breathe and that some dusts are more dangerous than others. Therefore, knowledge of the com-position of dusts is important in evaluating the hazard entailed on exposure. At present, free silica, of which quartz is the most abundant form, is considered one of the most significant dusts, from the standpoint of pneumoconiosis, and one State5/ has established permissible limits of air dustiness on the basis of the free-silica content of rock. The amount 06 free silica in materials used for rock dusting also has been limited.6/ Determination of free silica or quartz, therefore, is important.

Jan 1, 1940

By William M. McKewan

The U.S. Bureau of Mines has established a wire rope research laboratory to examine the factors that affect the life of wire rope. Ropes of sizes ranging from 3/4 to 2 in. in diameter and from 2 to 35 ft in length were tested to determine their breaking strength, elongation, and torque. This was done to characterize the test equipment on ropes used in mine hoisting systems.

Jan 1, 1990

By Thomas J. Peters

In 1988, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 34,310-acre Diablo Mountain (Additional) study area (OR-001-058), in order to evaluate its identified mineral resources and occurrences. The study area lies along the east shore of saline Summer Lake in Lake County, OR, about 145 miles southeast of Bend and 45 miles northwest of Lakeview. The climate is semiarid and temperate, and the study area is almost treeless. Geologically, the (Additional) study area is in a region of fault block-formed mountains and basins, characterized by interior drainage. The area is mainly underlain by unconsolidated Quaternary and Pleistocene lake and playa sediments, which may include subsurface evaporite mineral deposits and resources. Near the center of the eastern margin of the study area are an occurrence of dolomitic limestone of unknown extent, and an area of basalt outcrop totaling 1.5 square miles. A veneer of windblown sand covers about one-half the study area.

Jan 1, 1989

By R. J. Leary

Significant improvements in surface conditions or mechanical properties of steels have been attributed by several investigators to ladle additions of small quantities of rare-earth metals or their oxides. To investigate systematically these effects in wrought and in cast plain carbon and alloy mechanical steels containing approximately 0.35 percent carbon, heats of four representative compositions were melted by the Bureau of Mines in a 4-ton open-hearth furnace. Each heat was cast into three sets of ingots to exemplify respectively, treatments with (1) rare-earth metals, (2) rare-earth metal oxides, and (3) an untreated set as a control. The development of melting, casting and rolling practices is described and discussed. Lance injection of oxygen shortly after melt raised the temperature of the metal immediately as much as 500° F., principally because mechanical agitation exposed the high-carbon metal to the flame and furnace root. An exceptional degree of superheat in the metal at the termination of the refining period was attributed to oxygen injection during the refining period. Bath temperatures higher than industrial practice were permitted by the all-basic furnace lining. Rates of carbon elimination as high as 0.036 percent carbon per minute were achieved by oxygen injections.

Jan 1, 1961

By Beverly W. Dunning

The effect of vacuum melting on the elimination of gases and nonmetallic inclusions for six low-alloy steels was investigated. The purpose of these studies was the analysis and comparison of differences in gas content and inclusions in air-melted and vacuum-melted steel. Data obtained from melts of 1-1/4 to 20 pounds indicate that vacuum melting decreases the number and size of nonmetallic inclusions and at the same time increases the degree of dispersion of the remaining inclusions. These improvements are undoubtedly related to the elimination of approximately 80 percent of the nitrogen and 90 percent of the oxygen as well as most of the undesirable metallic trace impurities.

Jan 1, 1961

By D. Harrington

We Americans fondly believe that ours is the greatest , most progressive and most civilized country in the world , but the cold statistical facts reveal that we apparently have little appreciation for the lives of those whose efforts of various kinds give us whatever greatness we have . The latest available statistics indicate that the annual death rate per 100,000 persons , from accidents is nearly 80 , or far higher than that of any other country in the world ; it is more than double the rate in Denmark , Belgium, Netherlands , France , Sweden , Italy , Ireland , Germany , Norway, and Austria; it is practically double the rate in England and Wales and in Japan , and is from 25 to 60 per cent higher than the corresponding rate in Scotland , New Zealand , Australia, Switzerland , and Canada . And added to this is the fact that of the main industries of the United States mining has by far the worst accident record , viewed from either the frequency or the severity basis . The National Safety Council's latest figures for 27 of the country's main industries give mining the highest or worst accident frequency rate, 74.43 in 1929 ; meat packing comes next with 55.94 , and construction third with 50.41 . In accident severity in 1929 mining also was the worst offender , with a rate of 9.99 ; quarrying is second with 6.11 , and construction third with 4.62 . Metal mining's frequency rate in 1929 was 52.16 , as against 69.25 for bituminous coal mining ,99.68 for anthracite mining, and 74.43 for the entire mining industry ; accident severity for metal mining in 1929 was 5.99 , as against 11.69 for bituminous coal mining , 10.87 for anthracite mining , and 9.99 for the mining industry as a whole . Although this figure indicated that metal mining is on a much safer plane than either bituminous or anthracite coal mining, the frequency rate of 52.16 for metal mining was higher in 1929 than the frequency rate of all but one of the other 26 industries about which data are available ; the metal mining severity rate of 5.99 , while much better

Mar 1, 1932

By P. T. Brooks

The selective recovery of nickel and cobalt from impure raw materials is being investigated by the Bureau of Mines as part of a program to develop improved procedures for preparation of pure metals. A combination solvent extraction-electrolytic process has been developed in the laboratory that enables preparation of high-quality nickel and cobalt from nickel oxide containing, in percent, 76 nickel, 0.8 cobalt, 0.5 magnesium, 0.2 iron, and lesser quantities of copper, zinc, and other metals. The oxide was smelted, using carbon as reductant, and cast into anodes. These anodes subsequently were dissolved in diaphragm-type electrolytic cells. Nickel and cobalt were deposited separately from appropriate electrolytes, concurrent with dissolution of the impure anodes. Anolyte containing nickel and cobalt in the form of chlorides and sulfates was treated for removal of impurities and separation of nickel and cobalt. First, iron and aluminum were removed as hydroxides by adding nickel hydroxide to raise the pH of the anolyte from 2.3 to 4.5. Next, the pH was adjusted to 2 by adding hydrochloric acid, and the solution was treated by solvent extraction to separate nickel and cobalt.

Jan 1, 1963

By W. O. Vanderburg

This paper describing the methods of concentrating tungsten pros at the mills of the Atolia Mining Co. is one of a series of similar papers being prepared by the United States Bureau of Mines. The writer acknowledges the assistance and cooperation of A. V. Udell, president, Louis Warnken, bookkeeper, and C. K. Dennis, superintendent, of the Atolia Mining Co. in the preparation of this paper.

Jan 1, 1931

By Manuel Gomez

A general prediction model for the Hardgrove grindability index was constructed from 735 coal samples using the proximate analysis, heating value, and sulfur content. The coals used to develop the general model ranged in volatile matter from 12.8 to 49.2 percent, dry basis, and had grindability indexes ranging from 35 to 121. A restricted model applicable to bituminous coals having grindabilities in the 40 to 110 range was developed from the proximate analysis and the petrographic composition of the coal. The prediction of coal grindability within a single seam was also investigated. The results reported support the belief that mechanical properties of the coal are related to both chemical and petrographic factors of the coal. The mechanical properties of coal may be forecast in advance of mining because the variables used as input to the prediction models can be measured from drill core samples collected during exploration.

Jan 1, 1970

By C. R. Stephan, N. B. Greninger, J. R. Lipscomb

The U.S. Bureau of Mines and the U.S. Mine Safety and Health Administration (MSHA) are participating jointly in a research program to evaluate the strength characteristics and air-leakage resistance of various proposed seal designs for use in underground coal mines. The full-scale seals were constructed in the USBM's experimental mine at the Lake Lynn Laboratory, air-leakage tested, then subjected to pressure pulses of 20 psig or greater. bjected to pressure pulses of 20 psig or greater. In experiments prior to this study, seven seal designs using solid-concrete blocks were tested. Only the standard-type seal passed the explosion and air-leakage criteria. Tests also were performed on four seals constructed with low-density foam blocks. All four of these seal designs withstood the pressure pulse. In more recent studies, nine cementitious foam seal designs of varying thicknesses and densities were investigated. Six of the nine designs successfully survived the explosion overpressures. Six wood- block convergence seals also have been tested. The typical 3-ft-thick, wood-block seal design currently used in many coal mines did not maintain its integrity, in the absence of convergence forces, following the explosion test. Five modified wood-block seals successfully withstood the 20-psig pressure pulse. Based on these tests, three alternative seal construction materials, cementitious foam, low-density foam block, and wood, have been approved by MSHA for use in underground coal mines.

Jan 1, 1993

By Christopher Van Dyke, Knox Van Dyke, Lixin Wu, Jaime Gutierrez

"I. INTRODUCTION(SILICA, THE LUNG, INFLAMMATION, AND FIBROSIS)Inhalation of respirable-size silica (0. I to 5 µm in diameter) deposits the particles in the deep spaces of the Jung where oxygen is exchanged. The resulting pattern of inflammation is substantially different compared to that observed from other inhaled substances such as carbon, polystyrene titanium dioxide etc. 1 Following the inflammatory reaction the body attempts to isolate the damage by walling off the area via fibrosis. 2 The unique nature of the inflammatory response to silica makes it logical to infer that fibrosis is a later-stage manifestation of the initial inflammatory damage. In addition to the inflammation extensive lysis and cellular death particularly to macrophages and neutrophils, can occur, depending on the dose of silica.' The ingestion of significant amounts of silica by macrophages and neutrophils produces an inflammatory sequence which activates the lipoxygenase pathway of arachidonic acid metabolism and produces platelet activating factor (PAF) and leukotrienes (LT).4·5II. CALCIUM IONOPHORE MIMICS SILICA TOXICITY IN VITROPhagocytic cells exposed to silica in vitro produce PAF and LT. This response is reminiscent of phagocytic cells exposed to the calcium ionophore (A23 l 87) in the presence of ionic calcium.6-8 A23 l 87 forms a complex with free ionic calcium which passes through cellular membranes, thus transporting calcium inside the cell. The increased intracellular calcium concentration triggers the production of small amounts of prostaglandins large amounts of LT. PAF and. depending on dose cellular death (see Figure 1 ). Could silica cause LT production and cellular death by a similar mechanism? How could silica - an inert solid - act in a similar fashion as a soluble stimulant? Clearly the negative SiO2 and OH- surface of silica can bind calcium ions9 and therefore could theoretically act as a solid-state ionophore releasing bound calcium inside of cells following phagocytosis."

Jan 1, 1998

By Albert W. Deurbrouck

This report describes the preparation characteristics of 23 coal samples collected from nine of the more significant coalbeds of Fayette County, W. Va. In 1963 almost 5.4 million tons of medium to high volatile B coals of excellent quality for metallurgical and steam markets were produced in Fayette County. Of the 23 coal samples collected 11 would require some upgrading to pro-vide metallurgical quality products, 11 were acceptable as received, and 1 was a noncaking coal. Cleaning these coals to metallurgical standards would require only the removal of the sink 1.58 specific gravity material which would be quite easy as very little near-separating-gravity material was present at this gravity.

Jan 1, 1965

By G. E. McElroy

"The development of certain mines in the East Tintic mining district, Utah, has been hindered considerably by the presence in the rock strata of heavy irrespirable gases which at times flood the lowest working places, as well as by abnormally high rock temperatures in the lower horizons. A study of these features was completed in the spring of this year, and the information obtained is summarized here.Heavy gases.Only four mines have been affected to date by the presence of heavy gas, and only one of these is producing lead-silver ores in quantity. These four embrace a territory extending about three miles north and south and about two miles east and west, while both within and fringing on this territory are a number of prospects which have not been affected.Thus far no fatalities have resulted from gas inflows, but a number of men have been temporarily overcome, and a few have had narrow escapes from death by suffocation. That the record is not more serious is mainly due to the fact that the gas inflow, as a rule, is relatively slow, mining operations have been quite carefully conducted, and the presence and extent of a gas inflow can be easily determined by its extinguishing action on the flame of miners' lights.When first encountered, about 1910, gas inflows occasioned much lost time. In some months the lost time averaged as much as ten days, while one mine cites for a certain month a maximum of 26 days lost out of a possible 28 working days. With improvements in mechanical ventilation and the passing of time, interference with work from the presence of gas has gradually lessened. During the last few winters, the main trouble has been with the mines being flooded with gas overnight when fans were not operated, although men have been driven out of the lowest development openings several times each winter with fans operating. At present, the main danger is in the lowest development openings having only one exit, wherein men might be trapped and possibly suffocated during an unusual and extremely rapid inflow of gas, or during an ordinary inflow, should the one source of power for the fan be disabled."

Aug 1, 1921

By Milford L. Skow

Utilization of domestic ores in the winning of metallurgical alumina requires a convenj.ent method of treating siliceous bauxites and other aluminous materials. In the United states there are only small reserves of high-grade bauxite but considerably larger tonnages of low-grade material. In addition, there are large deposits of high-alumina clays. If these high-silica bauxites or high-alumina clays could be beneficiated, either by are dressing or by chemical dissolution to remove a large proportion of the silica, then the potential reserves of aluminum ores would be increased materially. Faced with a similar situation, the German industry, chiefly dependent on high-grade French bauxites prior to World War II, was compelled during the war to Use lower-grade ores. For desilicating the lower-grade bauxites before the Bayer treatment, a method was developed in which the bauxite was calcined and then given a dilute caustic leach preliminary to the pressure digestion. It was planned to regenerate the caustic by treatment of the desilication liquor with lime. As European bauxites are mineralogically different from those found in this country, preliminary work was undertaken to determine whether this process might be applied to domestic materials. The results of this work, along with a review of the German process, are presented in this report.

Jan 1, 1950

By R. V. Ramani

"In Part 1 of this two-part paper the characteristics of mine disasters and their effects are presented with case studies from coal, metal and non-metal mines leading to an amplification of their causes and opportunities for control. The disasters discussed encompass those which threaten the health and the safety of miners and those which affect the general population. In Part 2 of the paper, which will be published in the November 1995 issue of Natural Resources Forum, the approaches to hazard and disaster control are reviewed with particular attention to laws and regulations to promote health and safety at the workplace, and general welfare in mining communities. Further, a systems approach to disaster control is outlined.The mining industry is one of the three basic industries the other two being agriculture, and wildlife and fisheries. It is the process of mining which makes available the riches of the earth - the energy and mineral resources - to benefit humanity. In fact the progress of the human race through the ages is indelibly attached to prowess in exploiting these riches. The stone, iron and bronze ages are markers not just of a time in history but achievements of monumental proportions in the mining and beneficiation of natural resources. Even in agriculture, the remarkable success stories are associated with the prudent use of mined products to enhance production and productivity. The significance of a thriving mining industry to the wealth and security of a nation is therefore unquestioned.Unfortunately, the public's image of the mining industry is often associated with the mining disasters which receive wide coverage in the local and national media. Mine disasters command tremendous attention because of their infrequent occurrence and the extent of human suffering involved. Whether it is an explosion or a fire, or the opening or closing of a mine, the lives of people are touched by the personal and societal impacts of these events.Courts of inquiry of mining disasters have often concluded that the disaster situation was ever present and could have been detected with diligent search. In addition human error has been identified as one of the most frequent immediate causes for the precipitation of the disaster. For the most part, then, mining disasters are caused by man."

Dec 1, 1996

By Albert L. Brautigam, Michael C. Leigh, August J. Kwitowski

The U.S. Bureau of Mines developed and tested a teleoperating system to control a new highwall mining system. A remote operator was provided out-of-sight sensory information and control of coal extraction and haulage equipment. Surface and production testing proved that the teleoperating system supplied the operator with sufficient sensory information to operate the mining system. Details on the teleoperating system provided in this report include (1) sensor selection, (2) a description of the electronic control system, (3) equipment selection and modifications, (4) the positive test results, and (5) recommendations for system improvements.

Jan 1, 1992

By S. J. Schatzel, J. Cervik, A. A. Campoli

The cross-measure borehole technique is being studied by the Bureau of Mines as an alternative to the use of surface gob boreholes as a means of controlling methane in gobs during longwall mining. Small-diameter holes are drilled from underground locations into strata overlying the mined coalbed. When the roof strata are fractured by the mining opera- tion, a partial vacuum applied to the boreholes draws the methane out of the fractured strata and prevents it from entering the mine ventilation system. Tests in the Upper Kittanning Coalbed showed that 50 pct of the methane produced by the longwall mining operation was captured by the cross-measure boreholes. Borehole inclination and penetration into the gob are two important borehole parameters that affect the performance of the cross-measure borehole system.

Jan 1, 1983

By M. M. Tilman

The Bureau of Mines conducted research to determine the feasibility of strengthening experimental magnesium-base sheet alloys by strain softening induced by controlled cold rolling followed by selective heat treatment. Relatively small alloying additions having potential for producing strain softening were selected from metals that are readily avail-able. Tensile properties comparable to minimum properties of the most commonly used magnesium-base sheet alloy AZ31B, in the H24 condition (strain-hardened and partially annealed), were obtained in an Mg-IMM (mischmetal)-O.5Mn alloy after strain-softening rolling followed by heat treatment. Tensile properties of the experimental alloys in certain conditions are also compared with minimum tensile properties of other standard magnesium sheet alloys. Incidental to the principal objectives, apparent superplastic behavior was observed in three experimental magnesium-base alloys containing MM, MM plus manganese, and MM plus zirconium.

Jan 1, 1985