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By Karl J. Dreher, Charles C. Hennig, Gregg A. Scott

INTRODUCTION Theodore Roosevelt Dam is a cyclopean-masonry, gravity-arch dam located on the Salt River northeast of Phoenix, Arizona. Construction of the dam began in 1903 and was completed in 1911. The dam is about 85 m high with a total reservoir capacity of about 1.7x109 m3. Raising the dam is now being considered to provide additional water storage and flood control. This paper describes preliminary analyses performed to assess foundation stability for increased loading resulting from raising the dam and reservoir water surface about 12 m. The foundation of Theodore Roosevelt Dam consists of variably metamorphosed limes tones, sands tones, mudstones, and shales. Bedding uniformly strikes nearly normal to the river (N 40º W) and dips upstream at 25 to 30º. The rock is cut by four prominent joint sets as indicated by the joint contour diagram shown in figure 1A. The diagram was developed from surf ace observations and vertical drill core oriented relative to the bedding. Sampling biases account for the differences in concentrations of various joint sets. However, field observations indicate that all sets are relatively prominent, planar, and continuous. SEEPAGE ANALYSES Consistent with practice at the time of construction, no foundation drainage was installed at Theodore Roosevelt Dam. Finite element seepage analyses were therefore performed to study the potential for large uplift pressures in the foundation. The dam has steep abutments and is curved in plan as shown in figure 1B. The effects of modeling the seepage two-dimensionally, radially symmetric about the dam's axis center, and three-dimensionally were therefore com-

Jan 1, 1982

By Arif Emre Dursun, Ali Aras, Hakan Özşen

Specific energy (SE) is defined as the amount of work required to cut a unit volume of rock and is used to estimate the performance of excavation machines. Generally, the SE value is produced from full-scale or small-scale rock cutting tests. However, these tests require expensive equipment and experienced personnel, and the testing procedure is time consuming and impractical. Therefore, for estimation of SE, this study aimed to find a solution to estimate SE using rock mechanics test results and Bond work index values (BWi), which can be produced in a more practical, less time-consuming manner and with inexpensive test equipment. Small-scale rock cutting, rock mechanics and Bond work index tests were carried out on seven rock samples, which can be grouped into two different type of rocks: marble and travertine. In addition, the instantaneous cutting rates (ICR) of a selected roadheader were calculated using SE values. Rock mechanics tests performed in this study were uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), ultrasonic velocity (Vp), Schmidt rebound hardness (RL), corrected point load index (Is(50)) and density (ρ). The simple regression method was used to estimate SE from rock properties and BWi. As a result of this simple regression, a significant and highest correlation was found between SE vs. UCS and Is(50). A good correlation was found between SE vs. BTS, RL and BWi values. A moderate correlation was found between SE vs. Vp and ρ.

Jul 28, 2021

By J. D. Kalasky, Stephen Krickovic

A degasification experiment was conducted in a Pocahontas No. 3 coalbed mine in Virginia. It involved (1) drilling holes in the coalbed in the out- side headings of a set of five being developed in virgin area, and (2) conducting a methane emission rate study as mining progressed and additional holes were drilled. Degasification from all drill holes except the longest in each of the outside headings and the first three drilled (excluding the in-situ pressure hole), was erratic and inconsequential in methane emission rates. The two longest holes liberated 66 and 79 cfm of methane, which is significant for the coalbed, but such quantity lasted a relatively short time; the first three were uniform but low in methane emission.

Jan 1, 1972

By Scott A. Walker, Roberto A. Lopez, Lori A. Simpson, David A. Shook

500 Folsom Street is part of the new Transbay neighborhood in San Francisco, which is being redeveloped after the 1989 Loma Prieta Earthquake damaged a freeway viaduct; removal of the viaduct created parcels of land available for development. The development consists of a 42-story residential tower with a six-level basement. The slender, core-only structure was designed using performance-based seismic design. Subsurface conditions include undocumented fill, Dune sand, marsh deposits, sand, and clay, all overlying sloping bedrock of the Franciscan Formation. The building is supported on a 10-foot-thick mat foundation approximately 62 to 72 feet below street grades; clay, sand, and bedrock are all present at mat subgrade. Under a portion of the mat, sand susceptible to liquefaction was present. The variable subgrade conditions and potential for ground failure, along with the depth of mat subgrade below street grade, created a challenge for the design and construction team to solve. The ground below mat subgrade needed to be improved to mitigate the liquefaction potential and provide more uniform support. The areal extent and depth of ground improvement necessary to support the mat with an acceptable amount of deformation was determined. Settlement was analyzed and subgrade moduli were provided for design of the mat, with multiple iterations performed to converge between the geotechnical and structural models. Based on the project schedule and logistics, it was beneficial to work from street grade to improve the ground. In order to target the depths below the mat and minimize wasted effort and materials within the depth of excavation, grids of jet grouting were determined to be the most economical ground improvement method; however, it was challenging to install the columns from 65 feet above the top of the target zone. During installation, QA/QC was performed to check that the jet-grouted columns were installed to the design depth and diameter and developed the design strength.

Jan 1, 2018

By J Pan, G Qiu

In this paper, an analysis is made of the present situation in the Chinese steel industry and its demand for iron ores. It is shown that the demand for iron ores has been growing substantially with the rapid development of the steel industry all over the world, especially in China. However, the iron ore market is currently in the situation where supply exceeds demand due to the economic crisis, with more investment in mines and less output of steel for several years ahead all over the world. Gigantic pressure is confronting the Chinese steel mills due to the too high and irrational price of iron ores. It is time to return the price of iron ores to a normal position much closer to their value. More attention has therefore been paid to developing low-grade and complex iron ore resources in China due to the irrational price of imported iron ores. More innovative mineral processing processes have been developed to tackle these complex resources. A systematic introduction to the development of beneficiation processes for low-grade iron ores is provided, including upgrading low-grade siderite, limonite, micron sized haematite and magnetite resources.

Jan 1, 2009

In many lines of engineering, much excellent standardization work had been done before the war but the war emphasized its importance and showed most clearly the need of cooperation to prevent the confusion caused by the promulgation of overlapping standards by independent bodies. The American Institute of Mining and Metallurgical Engineers, American Institute of Electrical Engineers, American Society of Civil Engineers, American Society of Mechanical Engineers, and American Society for Testing Materials, recognizing the value of what had been done, invited the Government Departments of War, Navy and Commerce to appoint representatives to act with them to continue this work; the body so formed is the American Engineering Standards Committee. It has required time to definitely formulate its objects and to arrange methods for accomplishing them that would be effective without interfering with the many organizations that have been doing such excellent work in this line. The American Engineering Standards Committee has just completed and adopted a revision of its Constitution, which has been sent to the Governing Boards of all the Departments and Societies represented on the Committee with a request for its ratification. The new Constitution changes the name to American Engineering Standards Association as more fittingly indicating the wide scope of the interests involved. The objects of the association are stated as follows: 1. To unify and simplify the methods. of arriving at engineering standards, to secure cooperation between various organizations and to prevent duplication of standardization work. 2. To promulgate rules for the development and adoption of standards, 3. To receive and pass upon recommendations for standards submitted as provided in the Rules of Procedure, but not to initiate, define, or develop the details of any particular standard. 4. To act as a means of intercommunication between organizations and individuals interested in the problems of standardization. 5. To give an international status to approved American engineering standards. 6. To cooperate with similar organizations in other countries and to promote international standardization.

Jan 7, 1919

Assess the technical feasibility of mining small and/or deeply buried frozen placer deposits from the surface through boreholes.

Jan 1, 1997

By G. F. Revey

Most commercial explosives contain 70 to 94% ammonium nitrate, by weight. When portions of these explosives end up in shot rock and ore, through spillage or incomplete detonation, ammonia and nitrates leach out of them and into ground water. In recent years, State and Federal regulators have been applying more stringent water quality standards, particularly at new mines and development projects. Bulk ANFO, a mixture of ammonium nitrate and fuel oil, is the explosive of choice at most mines, when mining conditions allow it. ANFO use is desired because it less costly than other explosives, but when spilled it dissolves readily in water. Several case histories in the United States and Canada show a clear connection between uncontrolled losses of bulk explosives and high nitrate levels in mine effluents. Mining companies have tried several approaches to reduce ammonia and nitrate levels in groundwater. They either control explosive losses, or they treat mine effluents at the end-of-pipe. This paper addresses the former solution --controlling explosive losses. For both packaged and bulk explosives, guidelines designed to limit losses during storage, handling and use, are described in detail.

Jan 1, 1995

By G. J. Hasenfus

This paper presents the results of an extensive hydrological and geomechanical monitoring program which Gas conducted at a longwall coal mine in W. Va. The field program included monitoring of groundwater levels. overburden hydraulic conductivity, overburden movement, and surface subsidence relative to the passage of the longwall. Overburden geology and rock strength characteristics were evaluated prior to mining. A postmining corehole was drilled to evaluate main roof fracturing. An overburden response model is proposed based on the correlations between hydrological and geomechanical data.

Jan 1, 1988

By H. Burger

For mine planning in the hardcoal industry the reliable prediciton of the properties of a deposit-both ahead of the zone to be worked as well as of zones at depths not yet developed - may help improve the production results of workings. With the wide spacing of exploration drillings usual in the coal industry, it is hardly possible to establish adequately reliable plans just by simple kriging methods. During the exploration phase a decision has to be made whether the zone ahead of a face area is economically profitable and, in addition, accessible and safe in order to be included in the production planning. It is, first of all, important to gather global information on certain parts of the planning area it the form of local estimates. Moreover, cut-off problems play a critical role, e.g. if there are set cut-off thicknesses as a criterion for minability or if safety aspects have to be considered. Conditional simulation appears to be a useful geostatistic method in order to localize or predict areas of potential rock burst hazard - based on geological criteria in conjunction with the guidelines by mining authorities - in the zones ahead of a working. It is a means of providing an objective basis for the evaluation and planning of mining activities.

Jan 1, 1986

By W. E. Wallace, C. A. Hill, M. J. Keane

"Diesel exhaust particulate material from exhaust pipe scrapings of two trucks, diluted automobile diesel exhaust particulate material collected on filters, and two oil shale ores were prepared for the Ames mutagenrcity assay by dichloromethane OOP ex¬traction, by dispersion into 0.85% saline, or by dispersion into dipalmitoyl lecithin (DPL) emulsion in saline. Salmonella typhimunum TA98 was used to detect frameshift mutagens in the samples. Samples of diesel soot gave positive mutagenic responses with both DCM extraction and DPL dispersion, with the DPL dispersion giving higher results in some cases. The results suggest that possible mutagens associated with inhaled particles may be dispersed or solubilized into the phospholipid component of pulmonary surfactant and become active in such a phase.INTRODUCTIONThe Ames Salmonella/microsome assay (Ames et al., 1975) has been shown to be a useful test for detecting genotoxic properties of various agents. Hundreds of specific chemicals have been screened (McCann et al., 1975), and the test has been applied for many types of environmental samples. Airborne mutagenic agents, for example, have been found in urban air (Chrisp and Fisher, 1980; Hughes et al., 1980; Ro· senkranz et al., 1978), in diesel engine exhausts (Huisingh et al., 1978), and in the by-products of coal combustion processes (Chrisp et al., 1978).Samples of airborne particles are typically collected on membrane filters, and undergo a rigorous extraction procedure with organic solvents and/or ultrasonic agitation (Clark and Hobbs, 1980). Often extracts are transferred to another solvent that is compatible with the assay system. These extraction procedures, while efficient from an analytical perspective, are not physiologically plausible. The questions that present themselves are whether a demonstrated mutagen can be taken up in vivo and whether the process is quantitatively or qualitatively different from the above laboratory procedure (Wallace et al., 1984).When a particle of respirable size is inhaled to the alveolar region of the lung, its first physiological contact is with pulmonary surfactant that lines the inner surfaces of the alveoli. This surfactant is an aqueous fluid containing proteins, phospholipids, and other components (R. J. King, 1982). The principal phospholipid constituent is L·alpha-phosphatidylcholine, beta,gamma-dipalmitoyl, or dipalmitoyl lecithin (OPL) (l. C. King et al., 1981)."

Jan 1, 1989

By Shusen Cheng, Dongdong Zhou

The high temperature distribution in ironmaking and steelmaking industry is very important to control the smelting process. Although equipment is available to measure the temperature in the smelting process, in general it could just measure one certain point or only at discrete times. The real time temperature distribution in ironmaking and steelmaking is important because it could reflect reaction information and help to control the operation parameters. In this paper, a new method to detect the temperature distribution in ironmaking and steelmaking through the application of digital imaging system based on the color CCD was studied. In addition, the two-color method and partial least square method were used in the calculation model to improve the accuracy. The results agreed well with the measured temperature.

Mar 1, 2017

By G. L. Oldright

In the previous study that has been made by the authors on smelting in the lead blast furnace, the furnace examined was one that operated under conditions that have been considered as more or less normal up to the present time. That is although the furnace had in its charge a large portion of sinter, it also handled considerable quantities of naturally oxidized direct-smelting ore. Other ingredients, such as the limestone, were also added as fairly coarse material. The charges contained only about 24 per cent of lead. Until the changes incident to modern flotation began to take effect, many lead plants doing semicustom smelting in districts where competition was keen and much of the bonanza ore was exhausted were faced with the difficulty of obtaining enough lead to get a sufficient "lead fall" in the blast furnaces to clean the slag thoroughly and to separate it from the lead. A charge containing 24 per cent of lead would have been considered a very rich one by such smelters.

Jan 1, 1931

By Steve Kral

The mining industry in Colorado faces the same problems the industry faces throughout the United States and the world — record low commodity prices and increasing regulatory and environmental restrictions that seemed designed to curtail mining activities. Despite those obstacles, the mining industry in Colorado still contributes about $8 billion annually to the state’s economy in the form of base and precious metals, industrial minerals, coal and associated service businesses and jobs. So the 300 attendees at the102nd National Western Mining Conference felt reason-ably positive about the industry in their state. The meeting is the Colorado Mining Association’s annual conference and was held at the Broadmoor Hotel in Colorado Springs in November. The theme was “Mining in the New Millennium — Achievement + Innovation = Survival.” Experts from Colorado’s mining industry and abroad discussed the challenges faced by the mining industry as it enters the new millennium. They offered insights into how the industry will operate during the early years of the 21st century and how it will survive low prices and increased regulatory restrictions.

Jan 1, 2000

By R Aseervatham

The fast tracked mine development strategy attempts to blend feasibility studies and engineering/commissioning functions into a streamlined process. In this compressed process, environmental issues are difficult to control with respect to the optimisation of operational environmental performance. This paper presents a standard mine development process with specific focus on environmental issues, and contrasts this against Rio TintoÆs recent fast track experiences on the Hail Creek project (Australia), the Baranj project (India) and the Gokwe North project (Zimbabwe).

Jan 1, 1999

By G. B. Walker

The success of Heavy Media Separation, the static sink-float process, is evidenced by the operation of an estimated 300 installations treating many millions of tons per year of a wide variety of mineral products ranging in value from gravel to diamonds. The static heavy media process is usually limited to the treatment of plus 1/4 inch material. Mr. Victor Rakowsky, who was largely instrumental in the development and application of heavy media separation, recognized the need for a new apparatus and process which would extend the application of heavy media into the finer size range without placing a restrictive limit on the top size of the feed. He recognized the requirement for the application of centrifugal force to augment the force of gravity in separating fines by sink-float techniques.

Jan 1, 1966

By AIME AIME

As already announced, the XCIIId meeting of the Institute will be held at Toronto, beginning July 23, 1907. Hotel Headquarters will be at the King Edward Hotel, in which also the sessions will be held. The Queens, Rossin, Wallen, Iroquois and Palmer are good hotels not far from the King Edward. Members must secure their hotel-accommodations beforehand, by direct correspondence with the hotel they select. For those who neglect this precaution, the Local Committee will doubtless do what it can, but is unable to promise anything. Correspondence concerning this meeting (including notices of intention to attend it) should be addressed hereafter exclusively to Mr. W. G. Miller, Provincial Geologist, Bureau of Mines, Toronto, who is the representative of the Local Committee. The excursion to Cobalt, Lake Tenagami, Sudbury, etc., arranged by that Committee, involves the use of a special Pullman train for meals and lodging. After waiting a reasonable time to hear from members, the Local Committee has made its contract for Pullman cars. According to its latest report, there was still room for additional excursionists. Under this head, application made immediately to Mr. Miller may not be too late. Sessions for the presentation of papers, etc., will be held at the King Edward Hotel on Tuesday afternoon, July 23, and Wednesday morning and afternoon, July 24. The following papers have been accepted: 1. Sonic Reflections on Secrecy in the Arts, by James Douglas, New York, N. Y. .2. The Wilfley Table, by R. H. Richards, Boston, Mass. 3. The Tar-Sands of the Athabaska District, by' Robert Bell, Ottawa, Can. 4. The Occurrence of Nickel in Virginia, by Thomas L. Watson, Blacksburg, Va. 5. Coal-Briquetting in the United States, by E. W. Parker, Washington, D. C.

Jul 1, 1907

"IntroductionNOTE.-All figures on the supply and consumption of coal in Canada cited in this paper were collected and reported by the Dominion Bureau of Statistics. The friendly and efficient co-operation of the officials of the Bureau. is the foundation upon which it has been my privilege to rely in the preparation of this and two earlier papers ( 1). My thanks are due also to our own staff on the Dominion Coal Board, who spared neither time nor effort in helping to prepare this paper.STATISTICS are comparatively dull and, to many people, coal statistics are duller than most. Coal is, however, the one basic mineral upon which our whole way of life depends and it may be well if attention is drawn to this fact by an occasional statistical review of the coal position in Canada. The recent furore over the oil and gas discoveries has so obscured the basic position of coal in many minds that a little basic coal information may be useful. It is for this reason that, for the third successive year, a factual survey of the coal position is being presented.In the previous papers (1) explanations have been given of the basic considerations in the preparation of these reports and some special phases of the overall picture have been examined. For these explanations, the earlier papers may be consulted."

Jan 1, 1952

By T. Yukimasa

Hachinohe smelter, a zinc-lead blast furnace complex with the annual capacity of zinc plus lead of 100,000 tons, had originally treated normal zinc and lead sulfide concentrates. However, it is currently handling a great variety of raw feeds ranging from complex sulfides to oxidic recycled materials in view of resource economy, most of which are unsuitable for zinc electrolysis. This paper reports on some significant efforts recently carried out on improving sintering operation, i.e., the increasing use of secondaries against harmful ingredients like halogens, and the substantial reduction in energy use as the results of various modifications and improvements.

Jan 1, 1982

By B. Spigarelli

Carbon dioxide sequestration by conversion to carbonates has become a promising option for CO2 storage. Experiments were conducted to determine the feasibility of CO2 sequestration at ambient conditions using a Ca-rich industrial waste in a carbonate solution. The Ca-rich industrial waste used in this study was lignite fly ash. Fly ash was chosen because it is cheap, available near large CO2 point sources, already in powder form, and reactive due to amorphous properties. In the experimental set-up, CO2 absorption was inferred by monitoring feed and exhaust gas CO2 concentrations. The addition of an alkali to a fly ash-distilled water solution provided a 50% increase in CO2 absorption of the solution. Absorption time also increased by 50% compared to a fly ash-distilled water solution. TGA analysis was used to determine the extent of CO2 sequestration in the carbonate form. At a liquid to solid ratio of 20:1, the conversion of ?free? calcium to carbonates was 75%. A CO2 balance on the system concluded that at the current operating conditions 42% of the total CO2 fed to the system was sequestered in the carbonate form. SEM-EDS analysis of the fly ash particles before and after reaction with CO2 indicated that the carbonate compound being formed was calcium carbonate. The analysis identified rhomboidal structures on the surface of the fly ash particles after reaction with CO2, but not before. These rhomboids are characteristic of calcium carbonate formation and they had higher Ca, C, and O concentrations than the host spheres, suggesting calcium carbonate formation.

Jan 1, 2012