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The pilot scale testing of Australian coals for their NO, emissions was carried out at the ACTC to investigate the influence of coal properties, furnace conditions and different NO,, control strategies on NO,, emissions. The NOx emissions for the Australian coals tested were found to vary over a wide range and primarily depended on combustion temperature and excess oxygen conditions. These coals did not exhibit any fundamental difference in NOx levels to other world coals. Under similar combustion conditions, the conversion of coal nitrogen to NO. was found to be best correlated with coal rank parameter, R, max per centage. The use of staged combustion as a control strategy was shown to reduce their NOx levels by 56 - 77 per cent.

Jan 1, 1991

By William C. Larson

A study was conducted by the Bureau of Mines to provide quarry operators with information regarding (1) the effects of jointing and bedding on rock fragmentation when bench blasting in two small-scale (2.5-ft) limestone benches, and (2) the successful use of inexpensive equipment and field techniques to determine the orientation and spacing of joints and bedding separations within the quarry. Using inexpensive equipment, such as a pocket transit and steel and paper tapes, joint and bedding separations were mapped and their frequencies measured. Results from two small-scale bench blasts in the Stewartville member of the Galena limestone formation showed that when the row of vertical blast-holes was oblique to the vertical joint orientations, the backface expression was outlined by two relatively large triangular protrusions (joint surfaces). In this blast, part of the rock burden was unbroken. When the line of vertical blastholes paralleled a predominant joint set, all of the rock burden was broken and displaced. The thickness of fragments that had been displaced by a blast correlated with the observed bedding thickness in the bench.

Jan 1, 1974

By John T. Eash

DURING the course of the war the supply of tin in this country has steadily decreased and a continued effort has been made since the beginning of the emergency to use alloys that are either tin free or contain appreciably lower quantities of it. Even with the use of emergency materials, the tin supply has become particularly acute, and it is estimated that after recovery of the far eastern mines probably one to two years will be required before our normal annual supply is attained. One of the major tin-consuming fields is the bronze industry. Recommendations were made several years ago by the War Production Board toward the use of bronzes of lower tin content and manganese bronze and yellow brass for the customarily used tin-bronze alloys. The substitution of 88-5-5-2 copper-nickel-tin-zinc for composition G received considerable attention before the war, and consequently this alloy and modifications of it have been adopted for some current structural and pressure castings requiring high mechanical properties. Another of the commonly used bronzes is the 10 per cent tin, 10 per cent lead copper alloy for heavy-duty bearings. It has been known for some time that about 2.5 per cent nickel could be substituted for an equal amount of tin with retention of equivalent casting and tensile properties; however, it was desirable that a still greater conservation of tin be made. Consequently the present paper deals with the development of an alloy of low tin content that could be used for bearings. SELECTION OF COMPOSITION While the final criterion of the suitability of an alloy for a bearing must 0f course be determined by practical applications where all the ramifications of service conditions are encountered, certain short cuts in the initial selection of compositions are necessary to avoid an extensive and time-consuming investigation. The present program has been to match certain metallurgical properties of the 80-10-10 bronze that have been shown by previous investigations to be related to good bearing qualities. Such properties as microstructure, hardness, compressive yield strength, ductility, and castability have been considered, and certain simple wear tests have been made. Of the readily assessed characteristics desired in a good bearing alloy, one can be certain that a uniform distribution of lead is required in a leaded bronze. It has generally been found that segregation of lead is one of the chief difficulties with this type of material. Tin has a powerful effect on lead distribution, and with 10 per cent present produces a random distribution of chunky particles, such as are shown in Fig. I. In addition, the tin bronze contains the hard alpha + delta eutectoid constituent distributed through-

Jan 1, 1945

By A. Z. Lang, D. A. Hall

After a brief description of the causes of spontaneous heating and of general preventative methods, a detailed account is given of occurrences of spontaneous heating in the Main Seam (locally known as the 5/4 Seam) at Westoe Colliery. This seam is about 12 feet thick consisting of hands of coal and shale, but only 4 feet 6 inches is worked because of the thickness os strata in water-bearing rocks and the worked section is selected on quality considerations. An advancing longwall face in this seam (2nd South) began to heat after working for six months and ultimately had to be abandoned. By adopting retreating methods and mining narrow panels it has been possible to extract this coal at an excellent rate of productivity. The system of goaf ventilation is important, because the use of a bleed road would have given rise to dangerous conditions in a goaf which of necessity would have contained fallen coal. Preparatory seals were prepared at selected sites so that, if necessary, a panel could be sealed off quickly; these seals are completed as soon as possible (within three weeks) of finishing a panel. A gas sampling system has been instituted which includes daily sampling on the face and in the goaf, and weekly sampling at the stoppings of all completed panels. The coal has now been extracted from this seam for three years without any further difficulties from spontaneous heating.

May 23, 1905

By Curt Swanson, David C. Mathy, Dru R. Nielson, Kent VonAspern

In 1997, Central Contra Costa Sanitary District undertook the design of the Martinez East Side Trunk Sewer Improvements Project. Microtunneling was specified for approximately 1,035 meters (3,400 feet) of 600-mm (24-inch)diameter pipeline to be installed through estuarine soil deposits (San Francisco Bay Mud) and alluvium beneath the congested city streets of downtown Martinez, California. Directional drilling was specified for approximately 275 meters (900feet) of 200-mm (8-inch) diameter pipeline in four separate segments to be drilled through bedrock within narrow utility easements between residential properties. This paper presents a case history for the design and construction of themicrotunneling and directional drilling aspects of the project.

Jan 1, 1999

By L. Y. Zhang

The current status of metal hydride alloys for NiMH batteries was systematically reviewed. Extensive application-oriented research and development has successfully made the NiMH battery an important part, with growing potential, among rechargeable batteries. The rare earth based metal hydrides (AB5) have been considered the best alloy material for use in the negative electrode in NiMH batteries. However, being in demand for high performance electronic markets, the still young NiMH industry is facing serious technical challenges in developing better products. Among all the efforts to respond to the challenges, advanced AF3, alloys are in great demand: the capacity enhancement race requires new or improved alloys possessing higher volumetric capacity; price competition mandates MH materials with low cost; high performance under severe service environments calls for alloys with high corrosion resistance when subjected to electrochemical cycling; and finally, high power service requires the negative electrode to deliver current at high rates.

Jan 1, 1997

By C. J. Wilhelm

Brine produced from subsurface formations may be employed successfully instead of fresh water as a flooding, medium in the secondary recovery of oil. The feasibility of this substitution has been proved in the shallow "shoestring" area of eastern Kansas and northeastern Oklahoma, where the supply of fresh water often is limited. In this procedure all brine produced with the oil is returned to the formation and thus is prevented from contaminating streams and fresh-water supplies. This report includes a detailed description of a "flood project" in eastern Kansas studied by the Bureau of Mines. In an attempt to determine whether brine, when handled properly, can be used as effectively as fresh water in flooding oil from partly depleted, formations, an analysis was made of all .own conditions that influence flooding.

Jan 1, 1941

As one surveys the extensive taconite operations on the Mesabi Range, he may find it difficult to believe that only 15 years ago, the iron ore mining industry here was staring at its own imminent demise. Due to the high demands for iron ore during World War II the postwar period of 1946-1950, and the subsequent "police action" in Korea, there was rapid consumption of the Mesabi's already depleted ores, and some economists were giving the Range only 20-25 years of life. In the 13-year period 1941-1953, more than 850 million tons of iron ore were shipped to steel mills, an amount almost equal to the total production during the preceding 30 years. Proven ore reserves dropped from 1.1 billion tons in 1940 to 8.3 million tons in 1954, the largest decrease being recorded in the famed direct shipping ores.

Jan 9, 1968

Harrison W. Craver, Director The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and the publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 5, 1917

By Z. T. Bieniawski, Nicholson G. A.

This paper describes an empirical constitutive model for underground excavations in rock which equates the deformation modulus to the ratio of the principal stress difference to the major principal strain. The model requires failure criteria which define both the stress difference at failure and strain as a function, in part, of rock mass classification ratings (i.e. Bieniawski's RMR and Barton, Lien and Lunde's Q). Available failure criterion allows reasonable estimates of the stress difference for intact rock as well as rock mass. However, a suitable failure criterion for estimating strains at failure for rock was not available. Toward this end, this paper describes the development of an empirical criteria for defining strain at failure for intact rock as well as methodology for developing similar criteria for rock mass.

Jan 1, 1986

By J. B. Sellers, G. R. Haworth, P. G. Zambas

Rock mechanics research was carried out in the Anvil Points mine, Rifle, Colo., in the period 1964-1968, with the dual purpose of providing oil shale to the retorts of six major oil companies and to perform research on mining cycle operations to maximize extraction under safe conditions. An 80% extraction ratio within the mining area proved feasible. Test results provided data on optimum pillar and roof design. Studies of mine orientation showed that the mining headings should take into account the prevailing joint patterns and also the directions of the principal in-situ stresses acting in the region.

Jan 1, 1973

By Edward L. McHugh

The study area, which comprises 28,443 acres within the Jacumba Wilderness Study Area, is in the California Desert Conservation Area, and along the U.S.-Mexico border 25 miles west of Fl Centro, CA. The U.S. Bureau of Mines evaluation of mineral resources is based on examination of mining claims, known mineral occurrences, and mineralized zones during the fall of 1983. Limestone resources were identified inside the study area; tungsten resources may he present. Metasedimentary rocks intruded by Cretaceous Quartz diorite predominate in the study area. Tungsten and some gold have been found in skarn zones along intrusive contacts; limestone deposits are in the pre-Cretaceous rocks. Tertiary and Quaternary volcanic flows, pyroclastic rocks, clay beds, and diatomite in lake deposits nave been investigated for possible non-metallic resources. Evidence of mining or prospecting was found at 26 sites in or just outside the study area. In 1983, 106 claims were held in 13 claim groups. One claimant was sporadically prospecting for gold on claims in the north part of the study area in 1983, and gravel was being mined from alluvium 1/4 mile to the east.

Jan 1, 1985

Geological hazards such as faulting, basement ridges, and zones of "thin" (

Jan 1, 1998

By Quast K. B

The effects of metal ion addition rates and contact time on the activation of synthetic sphalerite using copper, cadmium and silver ions were determined in order to investigate the exchange characteristics at the mineral surface. The stoichiometry of the adsorption indicated that the activation of sphalerite involved both a simple ion exchange and redox process in which the activating ion and oxygen were reduced, and the mixed-sulphide surface was oxidised to produce elemental sulphur and a metal-deficient sulphide surface. Unactivated sphalerite was shown to be relatively hydrophilic, with recoveries usually less than 20 per cent for a five-minute float. Activated sphalerite could be readily floated without the use of a conventional collector. This inherent flotability of the activated sphalerite had previously been associated with the formation of a metal-deficient sulphide layer; however, this study emphasizses the significance of the surface oxidation processes occurring.

Jan 1, 1993

By W. Porter Place

The Trolleyphone was the first successful application of carrier current techniques to a DC power distribution system to provide voice communication between fixed points and moving locomotives and traveling cranes, This was a significant breakthrough because this not only in itself provided a useful new tool for industry, but the knowledge gained in the transmission of voice communication is paving the way for many other things, chiefly, remote control and indication systems which promise to have a far reaching effect during the upcoming age of automation. Once it has been established that we can communicate between men who operate machines, the next step will be to operate the machines themselves.

Jan 1, 1958

By S. Benedict Levin

In the spring of 1944, during the emergency In the supply of strategic mica, the Bureau core-drilled six aggregating 913 feet, at the Blister mica Trim. Cheshire County, N.H. These holes indicated a downward extension or the mica shoot which was being mined at that time and developed information essential for economic mining of the deposit.

Jan 1, 1949

By T. F. Mitchell

During the investigation or the occurrence of manganese deposits in western United States, Bureau of Mines' examining engineers collected samples from four manganese properties in the Death Valley region, California. These were supplemented by samples submitted by owners of two other properties in the same area. Extensive laboratory tests were made to determine the, amenability of the ores to standard ore-dressing concentration methods. A small sample of high-grade oxide manganese ore from the McWhinney property, San Bernardino County, Calif., was submitted by the owner. Although the sample would sinter directly to plus 48 percent manganese grade, it appeared probable that the ore, if mined in quantity, would be lower in grade and would require beneficiation. Therefore, testing was conducted to remove the chief gangue constituent, calcite. The National Resources, Inc., property (also known as the old Owl Hole mine) is in the Owl Hole Springs district, I mile from Owl Hole Springs, San Bernardino County, Calif., near the southwest corner of Death Valley National Monument. The ore deposits occur as small lenses or ,pockets, evidently .replacements in limestone and granite. Laboratory work was done on a representative sample of orb procured by Bureau engineers.

Jan 1, 1949

By A. Erdem

In this study, approximately 3 tons of coal sample taken from thickener entrance was prepared by mineral processing techniques and cleaned by gravity methods. The samples were classified to 5 size fractions by wet screening. The size fractions of +1mm and -1 +0.500 mm were chosen for direct consumption or cleaning by spirals. The studies by Multi Gravity Separator (MGS) were carried out with the -0.500 +0.280 mm and -0.280 +0.020 mm size fractions where the -0.020 mm fraction does not used in the experiments. The clean coal fractions of +1 mm and -1 +0.500 mm obtained by classification were subjected to lower calorific value (LCV), ash and total sulphur analyses. The results were 4168-4946 kcal/kg (on dry basis), 31.01-38.54 % ash and 4-4.27 % total sulphur content respectively. The results of the clean coal concentrated by MGS experiments in -0.500 +0.280 mm fraction was found 5918 kcal/kg LCV, 19.82 % ash content and 80.47 % combustible recovery. The results for the -0.280 +0.020mm fraction were 6004 kcal/kg LCV, 19.19 % ash content, 80.47 % combustible recovery respectively. With reference to the above experimental results, pre-economic evaluation studies were completed and decided to construct an additional unit to the plant. Capacity of the constructed unit is 75.000 t/y which corresponds $ 2.600.000 income in a year. General Directorate of Turkish Coal Enterprises concluded to apply this project to the other coal washing plants in the country due to the successful results of this study and laboratory studies has been going on by MTA currently. Keywords: coal tailings, mgs, recovery, washery, pre-economic evaluation

Sep 1, 2012

By William H. Walton, Clyde N. Baker Jr., Darren S. Diehm

"A 51-story concrete core and steel frame commercial office tower was recently constructed on the site of the former US Gypsum building in downtown Chicago, Illinois, USA The structure foundation reused several caissons from the demolished US Gypsum building supplemented with new belled caissons bearing on silty clay hardpan. Extensive in-situ pressuremeter testing was performed during the geotechnical investigation to determine allowable bearing capacity and better estimate building settlements. Problems during foundation construction along the south side of the building frame required remediation of two caissons. One caisson was supplemented with micropiles, while the second caisson was abandoned and replaced with a straight-shaft rock socketed caisson. To determine the effectiveness of the repairs, the building foundation settlements were monitored during construction.IntroductionIn 2001, The John Buck Company began development of a new office tower at the southeast corner of West Monroe Street and South Wacker Drive in Chicago, Illinois. The site was formerly occupied by the 18-story US Gypsum (USG) building. Mr. Clyde N. Baker, Jr. (Senior Principal at STS Consultants, Ltd .) served as the foundation engineer for USG which was completed in 1962. The building was founded on a forest of belled caissons bearing at elevation -56 Chicago City Datum (CCD). For reference, the ground surface at Upper Wacker Drive is approximately elevation +20 CCD. The bearing material was a hard silty clay, locally described as Chicago Hardpan. The foundation caissons were designed using an allowable bearing pressure of 16 ksf (766 kPa). In 1996, the USG superstructure was razed, and the three-level basement was converted to an underground parking ramp.South Wacker DevelopmentThe 51-story high-rise building was completed in 2005 with a structural height of 681 feet (208 m), and an internal space of more than 1,000,000 square feet (93 ,000 square meter). The typical floor size is 27, 700 square feet (2, 570 square meter). Renderings of the building are provided in Figures 1 and 2. The largest single tenant is the accounting firm of Deloitte & Touche, which occupies roughly 45% of the building space with over 3,000 employees."

Jan 1, 2005

By Paul F. Kerr

The uranium-producing areas near Marysvale, Utah provide an unusual group of veins and replacement deposits associated with a Pliocene-Oligocene intrusive and extrusive igneous complex. Aside from several scattered occurrences in older volcanics, uranium-bearing veins occur in intrusive quartz monzonite or granite and in nearby rhyolite. The veins in general trend within a few degrees of N55-65°E, are more or less vertical, and are found along the western margins of a quartz monzonite intrusive. The replacement deposits are found in rhyolite intrusives and also in the lower portions of rhyolite flows close to places where veins forming solutions rising through quartz monzonite came into contact with the rhyolite. At least 14 veins have been mined since uranium mining operations began at Marysvale some 16 years ago, while ore has been extracted through about 10 miles of underground workings. The active mmmg area is approximately 3000 feet long and in the central portion 1500 feet wide. Ores have been found over a vertical spread of almost 2000 feet, between the highest occurrence on Jungfrau Hill ( ca. 7200 feet) and the deepest discovery of ore in a drill hole near the Prospector Mine (ca. 5200 feet). Under existing mining and marketing conditions, mining along the veins in the main area appears to have reached an economic limit at about 500-600 feet below the surface. However, orebodies in the rhyolite and in the upper portions of veins close to the rhyolite are subject to active mining. Isotopic dates indicate that the uraninitebearing veins and replacements are late Miocene or Pliocene (ca. 10-13 m.y.), the rhyolite is Miocene (avg. 17.5 m.y.), and the quartz monzonite and granite intrusives are late Oligocene (23.6 to 26.0 m.y.). The older Bullion Canyon Volcanic Series which encircles the area is Oligocene (28 to 31.1 m.y.). Two generations of alteration occur: ( 1) Earlier alunitic veins and replacement bodies are found in the Bullion Canyon Volcanic Series, none of which have produced uranium; (2) Later argillic alteration associated with the introduction of uranium is found along veins, replacing glassy rhyolite dikes and replacing phases of the rhyolite.

Jan 1, 1968